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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/ceph/ceph_debug.h>
 
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/sched/signal.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/wait.h>
 #include <linux/writeback.h>
 #include <linux/iversion.h>
 
 #include "super.h"
 #include "mds_client.h"
 #include "cache.h"
 #include <linux/ceph/decode.h>
 #include <linux/ceph/messenger.h>
 
 /*
  * Capability management
  *
  * The Ceph metadata servers control client access to inode metadata
  * and file data by issuing capabilities, granting clients permission
  * to read and/or write both inode field and file data to OSDs
  * (storage nodes).  Each capability consists of a set of bits
  * indicating which operations are allowed.
  *
  * If the client holds a *_SHARED cap, the client has a coherent value
  * that can be safely read from the cached inode.
  *
  * In the case of a *_EXCL (exclusive) or FILE_WR capabilities, the
  * client is allowed to change inode attributes (e.g., file size,
  * mtime), note its dirty state in the ceph_cap, and asynchronously
  * flush that metadata change to the MDS.
  *
  * In the event of a conflicting operation (perhaps by another
  * client), the MDS will revoke the conflicting client capabilities.
  *
  * In order for a client to cache an inode, it must hold a capability
  * with at least one MDS server.  When inodes are released, release
  * notifications are batched and periodically sent en masse to the MDS
  * cluster to release server state.
  */
 
 static u64 __get_oldest_flush_tid(struct ceph_mds_client *mdsc);
 static void __kick_flushing_caps(struct ceph_mds_client *mdsc,
                  struct ceph_mds_session *session,
                  struct ceph_inode_info *ci,
                  u64 oldest_flush_tid);
 
 /*
  * Generate readable cap strings for debugging output.
  */
 #define MAX_CAP_STR 20
 static char cap_str[MAX_CAP_STR][40];
 static DEFINE_SPINLOCK(cap_str_lock);
 static int last_cap_str;
 
 static char *gcap_string(char *s, int c)
 {
     if (c & CEPH_CAP_GSHARED)
         *s++ = 's';
     if (c & CEPH_CAP_GEXCL)
         *s++ = 'x';
     if (c & CEPH_CAP_GCACHE)
         *s++ = 'c';
     if (c & CEPH_CAP_GRD)
         *s++ = 'r';
     if (c & CEPH_CAP_GWR)
         *s++ = 'w';
     if (c & CEPH_CAP_GBUFFER)
         *s++ = 'b';
     if (c & CEPH_CAP_GWREXTEND)
         *s++ = 'a';
     if (c & CEPH_CAP_GLAZYIO)
         *s++ = 'l';
     return s;
 }
 
 const char *ceph_cap_string(int caps)
 {
     int i;
     char *s;
     int c;
 
     spin_lock(&cap_str_lock);
     i = last_cap_str++;
     if (last_cap_str == MAX_CAP_STR)
         last_cap_str = 0;
     spin_unlock(&cap_str_lock);
 
     s = cap_str[i];
 
     if (caps & CEPH_CAP_PIN)
         *s++ = 'p';
 
     c = (caps >> CEPH_CAP_SAUTH) & 3;
     if (c) {
         *s++ = 'A';
         s = gcap_string(s, c);
     }
 
     c = (caps >> CEPH_CAP_SLINK) & 3;
     if (c) {
         *s++ = 'L';
         s = gcap_string(s, c);
     }
 
     c = (caps >> CEPH_CAP_SXATTR) & 3;
     if (c) {
         *s++ = 'X';
         s = gcap_string(s, c);
     }
 
     c = caps >> CEPH_CAP_SFILE;
     if (c) {
         *s++ = 'F';
         s = gcap_string(s, c);
     }
 
     if (s == cap_str[i])
         *s++ = '-';
     *s = 0;
     return cap_str[i];
 }
 
 void ceph_caps_init(struct ceph_mds_client *mdsc)
 {
     INIT_LIST_HEAD(&mdsc->caps_list);
     spin_lock_init(&mdsc->caps_list_lock);
 }
 
 void ceph_caps_finalize(struct ceph_mds_client *mdsc)
 {
     struct ceph_cap *cap;
 
     spin_lock(&mdsc->caps_list_lock);
     while (!list_empty(&mdsc->caps_list)) {
         cap = list_first_entry(&mdsc->caps_list,
                        struct ceph_cap, caps_item);
         list_del(&cap->caps_item);
         kmem_cache_free(ceph_cap_cachep, cap);
     }
     mdsc->caps_total_count = 0;
     mdsc->caps_avail_count = 0;
     mdsc->caps_use_count = 0;
     mdsc->caps_reserve_count = 0;
     mdsc->caps_min_count = 0;
     spin_unlock(&mdsc->caps_list_lock);
 }
 
 void ceph_adjust_caps_max_min(struct ceph_mds_client *mdsc,
                   struct ceph_mount_options *fsopt)
 {
     spin_lock(&mdsc->caps_list_lock);
     mdsc->caps_min_count = fsopt->max_readdir;
     if (mdsc->caps_min_count < 1024)
         mdsc->caps_min_count = 1024;
     mdsc->caps_use_max = fsopt->caps_max;
     if (mdsc->caps_use_max > 0 &&
         mdsc->caps_use_max < mdsc->caps_min_count)
         mdsc->caps_use_max = mdsc->caps_min_count;
     spin_unlock(&mdsc->caps_list_lock);
 }
 
 static void __ceph_unreserve_caps(struct ceph_mds_client *mdsc, int nr_caps)
 {
     struct ceph_cap *cap;
     int i;
 
     if (nr_caps) {
         BUG_ON(mdsc->caps_reserve_count < nr_caps);
         mdsc->caps_reserve_count -= nr_caps;
         if (mdsc->caps_avail_count >=
             mdsc->caps_reserve_count + mdsc->caps_min_count) {
             mdsc->caps_total_count -= nr_caps;
             for (i = 0; i < nr_caps; i++) {
                 cap = list_first_entry(&mdsc->caps_list,
                     struct ceph_cap, caps_item);
                 list_del(&cap->caps_item);
                 kmem_cache_free(ceph_cap_cachep, cap);
             }
         } else {
             mdsc->caps_avail_count += nr_caps;
         }
 
         dout("%s: caps %d = %d used + %d resv + %d avail\n",
              __func__,
              mdsc->caps_total_count, mdsc->caps_use_count,
              mdsc->caps_reserve_count, mdsc->caps_avail_count);
         BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
                          mdsc->caps_reserve_count +
                          mdsc->caps_avail_count);
     }
 }
 
 /*
  * Called under mdsc->mutex.
  */
 int ceph_reserve_caps(struct ceph_mds_client *mdsc,
               struct ceph_cap_reservation *ctx, int need)
 {
     int i, j;
     struct ceph_cap *cap;
     int have;
     int alloc = 0;
     int max_caps;
     int err = 0;
     bool trimmed = false;
     struct ceph_mds_session *s;
     LIST_HEAD(newcaps);
 
     dout("reserve caps ctx=%p need=%d\n", ctx, need);
 
     /* first reserve any caps that are already allocated */
     spin_lock(&mdsc->caps_list_lock);
     if (mdsc->caps_avail_count >= need)
         have = need;
     else
         have = mdsc->caps_avail_count;
     mdsc->caps_avail_count -= have;
     mdsc->caps_reserve_count += have;
     BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
                      mdsc->caps_reserve_count +
                      mdsc->caps_avail_count);
     spin_unlock(&mdsc->caps_list_lock);
 
     for (i = have; i < need; ) {
         cap = kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
         if (cap) {
             list_add(&cap->caps_item, &newcaps);
             alloc++;
             i++;
             continue;
         }
 
         if (!trimmed) {
             for (j = 0; j < mdsc->max_sessions; j++) {
                 s = __ceph_lookup_mds_session(mdsc, j);
                 if (!s)
                     continue;
                 mutex_unlock(&mdsc->mutex);
 
                 mutex_lock(&s->s_mutex);
                 max_caps = s->s_nr_caps - (need - i);
                 ceph_trim_caps(mdsc, s, max_caps);
                 mutex_unlock(&s->s_mutex);
 
                 ceph_put_mds_session(s);
                 mutex_lock(&mdsc->mutex);
             }
             trimmed = true;
 
             spin_lock(&mdsc->caps_list_lock);
             if (mdsc->caps_avail_count) {
                 int more_have;
                 if (mdsc->caps_avail_count >= need - i)
                     more_have = need - i;
                 else
                     more_have = mdsc->caps_avail_count;
 
                 i += more_have;
                 have += more_have;
                 mdsc->caps_avail_count -= more_have;
                 mdsc->caps_reserve_count += more_have;
 
             }
             spin_unlock(&mdsc->caps_list_lock);
 
             continue;
         }
 
         pr_warn("reserve caps ctx=%p ENOMEM need=%d got=%d\n",
             ctx, need, have + alloc);
         err = -ENOMEM;
         break;
     }
 
     if (!err) {
         BUG_ON(have + alloc != need);
         ctx->count = need;
         ctx->used = 0;
     }
 
     spin_lock(&mdsc->caps_list_lock);
     mdsc->caps_total_count += alloc;
     mdsc->caps_reserve_count += alloc;
     list_splice(&newcaps, &mdsc->caps_list);
 
     BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
                      mdsc->caps_reserve_count +
                      mdsc->caps_avail_count);
 
     if (err)
         __ceph_unreserve_caps(mdsc, have + alloc);
 
     spin_unlock(&mdsc->caps_list_lock);
 
     dout("reserve caps ctx=%p %d = %d used + %d resv + %d avail\n",
          ctx, mdsc->caps_total_count, mdsc->caps_use_count,
          mdsc->caps_reserve_count, mdsc->caps_avail_count);
     return err;
 }
 
 void ceph_unreserve_caps(struct ceph_mds_client *mdsc,
              struct ceph_cap_reservation *ctx)
 {
     bool reclaim = false;
     if (!ctx->count)
         return;
 
     dout("unreserve caps ctx=%p count=%d\n", ctx, ctx->count);
     spin_lock(&mdsc->caps_list_lock);
     __ceph_unreserve_caps(mdsc, ctx->count);
     ctx->count = 0;
 
     if (mdsc->caps_use_max > 0 &&
         mdsc->caps_use_count > mdsc->caps_use_max)
         reclaim = true;
     spin_unlock(&mdsc->caps_list_lock);
 
     if (reclaim)
         ceph_reclaim_caps_nr(mdsc, ctx->used);
 }
 
 struct ceph_cap *ceph_get_cap(struct ceph_mds_client *mdsc,
                   struct ceph_cap_reservation *ctx)
 {
     struct ceph_cap *cap = NULL;
 
     /* temporary, until we do something about cap import/export */
     if (!ctx) {
         cap = kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
         if (cap) {
             spin_lock(&mdsc->caps_list_lock);
             mdsc->caps_use_count++;
             mdsc->caps_total_count++;
             spin_unlock(&mdsc->caps_list_lock);
         } else {
             spin_lock(&mdsc->caps_list_lock);
             if (mdsc->caps_avail_count) {
                 BUG_ON(list_empty(&mdsc->caps_list));
 
                 mdsc->caps_avail_count--;
                 mdsc->caps_use_count++;
                 cap = list_first_entry(&mdsc->caps_list,
                         struct ceph_cap, caps_item);
                 list_del(&cap->caps_item);
 
                 BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
                        mdsc->caps_reserve_count + mdsc->caps_avail_count);
             }
             spin_unlock(&mdsc->caps_list_lock);
         }
 
         return cap;
     }
 
     spin_lock(&mdsc->caps_list_lock);
     dout("get_cap ctx=%p (%d) %d = %d used + %d resv + %d avail\n",
          ctx, ctx->count, mdsc->caps_total_count, mdsc->caps_use_count,
          mdsc->caps_reserve_count, mdsc->caps_avail_count);
     BUG_ON(!ctx->count);
     BUG_ON(ctx->count > mdsc->caps_reserve_count);
     BUG_ON(list_empty(&mdsc->caps_list));
 
     ctx->count--;
     ctx->used++;
     mdsc->caps_reserve_count--;
     mdsc->caps_use_count++;
 
     cap = list_first_entry(&mdsc->caps_list, struct ceph_cap, caps_item);
     list_del(&cap->caps_item);
 
     BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
            mdsc->caps_reserve_count + mdsc->caps_avail_count);
     spin_unlock(&mdsc->caps_list_lock);
     return cap;
 }
 
 void ceph_put_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap)
 {
     spin_lock(&mdsc->caps_list_lock);
     dout("put_cap %p %d = %d used + %d resv + %d avail\n",
          cap, mdsc->caps_total_count, mdsc->caps_use_count,
          mdsc->caps_reserve_count, mdsc->caps_avail_count);
     mdsc->caps_use_count--;
     /*
      * Keep some preallocated caps around (ceph_min_count), to
      * avoid lots of free/alloc churn.
      */
     if (mdsc->caps_avail_count >= mdsc->caps_reserve_count +
                       mdsc->caps_min_count) {
         mdsc->caps_total_count--;
         kmem_cache_free(ceph_cap_cachep, cap);
     } else {
         mdsc->caps_avail_count++;
         list_add(&cap->caps_item, &mdsc->caps_list);
     }
 
     BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
            mdsc->caps_reserve_count + mdsc->caps_avail_count);
     spin_unlock(&mdsc->caps_list_lock);
 }
 
 void ceph_reservation_status(struct ceph_fs_client *fsc,
                  int *total, int *avail, int *used, int *reserved,
                  int *min)
 {
     struct ceph_mds_client *mdsc = fsc->mdsc;
 
     spin_lock(&mdsc->caps_list_lock);
 
     if (total)
         *total = mdsc->caps_total_count;
     if (avail)
         *avail = mdsc->caps_avail_count;
     if (used)
         *used = mdsc->caps_use_count;
     if (reserved)
         *reserved = mdsc->caps_reserve_count;
     if (min)
         *min = mdsc->caps_min_count;
 
     spin_unlock(&mdsc->caps_list_lock);
 }
 
 /*
  * Find ceph_cap for given mds, if any.
  *
  * Called with i_ceph_lock held.
  */
 static struct ceph_cap *__get_cap_for_mds(struct ceph_inode_info *ci, int mds)
 {
     struct ceph_cap *cap;
     struct rb_node *n = ci->i_caps.rb_node;
 
     while (n) {
         cap = rb_entry(n, struct ceph_cap, ci_node);
         if (mds < cap->mds)
             n = n->rb_left;
         else if (mds > cap->mds)
             n = n->rb_right;
         else
             return cap;
     }
     return NULL;
 }
 
 struct ceph_cap *ceph_get_cap_for_mds(struct ceph_inode_info *ci, int mds)
 {
     struct ceph_cap *cap;
 
     spin_lock(&ci->i_ceph_lock);
     cap = __get_cap_for_mds(ci, mds);
     spin_unlock(&ci->i_ceph_lock);
     return cap;
 }
 
 /*
  * Called under i_ceph_lock.
  */
 static void __insert_cap_node(struct ceph_inode_info *ci,
                   struct ceph_cap *new)
 {
     struct rb_node **p = &ci->i_caps.rb_node;
     struct rb_node *parent = NULL;
     struct ceph_cap *cap = NULL;
 
     while (*p) {
         parent = *p;
         cap = rb_entry(parent, struct ceph_cap, ci_node);
         if (new->mds < cap->mds)
             p = &(*p)->rb_left;
         else if (new->mds > cap->mds)
             p = &(*p)->rb_right;
         else
             BUG();
     }
 
     rb_link_node(&new->ci_node, parent, p);
     rb_insert_color(&new->ci_node, &ci->i_caps);
 }
 
 /*
  * (re)set cap hold timeouts, which control the delayed release
  * of unused caps back to the MDS.  Should be called on cap use.
  */
 static void __cap_set_timeouts(struct ceph_mds_client *mdsc,
                    struct ceph_inode_info *ci)
 {
     struct ceph_mount_options *opt = mdsc->fsc->mount_options;
     ci->i_hold_caps_max = round_jiffies(jiffies +
                         opt->caps_wanted_delay_max * HZ);
     dout("__cap_set_timeouts %p %lu\n", &ci->netfs.inode,
          ci->i_hold_caps_max - jiffies);
 }
 
 /*
  * (Re)queue cap at the end of the delayed cap release list.
  *
  * If I_FLUSH is set, leave the inode at the front of the list.
  *
  * Caller holds i_ceph_lock
  *    -> we take mdsc->cap_delay_lock
  */
 static void __cap_delay_requeue(struct ceph_mds_client *mdsc,
                 struct ceph_inode_info *ci)
 {
     dout("__cap_delay_requeue %p flags 0x%lx at %lu\n", &ci->netfs.inode,
          ci->i_ceph_flags, ci->i_hold_caps_max);
     if (!mdsc->stopping) {
         spin_lock(&mdsc->cap_delay_lock);
         if (!list_empty(&ci->i_cap_delay_list)) {
             if (ci->i_ceph_flags & CEPH_I_FLUSH)
                 goto no_change;
             list_del_init(&ci->i_cap_delay_list);
         }
         __cap_set_timeouts(mdsc, ci);
         list_add_tail(&ci->i_cap_delay_list, &mdsc->cap_delay_list);
 no_change:
         spin_unlock(&mdsc->cap_delay_lock);
     }
 }
 
 /*
  * Queue an inode for immediate writeback.  Mark inode with I_FLUSH,
  * indicating we should send a cap message to flush dirty metadata
  * asap, and move to the front of the delayed cap list.
  */
 static void __cap_delay_requeue_front(struct ceph_mds_client *mdsc,
                       struct ceph_inode_info *ci)
 {
     dout("__cap_delay_requeue_front %p\n", &ci->netfs.inode);
     spin_lock(&mdsc->cap_delay_lock);
     ci->i_ceph_flags |= CEPH_I_FLUSH;
     if (!list_empty(&ci->i_cap_delay_list))
         list_del_init(&ci->i_cap_delay_list);
     list_add(&ci->i_cap_delay_list, &mdsc->cap_delay_list);
     spin_unlock(&mdsc->cap_delay_lock);
 }
 
 /*
  * Cancel delayed work on cap.
  *
  * Caller must hold i_ceph_lock.
  */
 static void __cap_delay_cancel(struct ceph_mds_client *mdsc,
                    struct ceph_inode_info *ci)
 {
     dout("__cap_delay_cancel %p\n", &ci->netfs.inode);
     if (list_empty(&ci->i_cap_delay_list))
         return;
     spin_lock(&mdsc->cap_delay_lock);
     list_del_init(&ci->i_cap_delay_list);
     spin_unlock(&mdsc->cap_delay_lock);
 }
 
 /* Common issue checks for add_cap, handle_cap_grant. */
 static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
                   unsigned issued)
 {
     unsigned had = __ceph_caps_issued(ci, NULL);
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     /*
      * Each time we receive FILE_CACHE anew, we increment
      * i_rdcache_gen.
      */
     if (S_ISREG(ci->netfs.inode.i_mode) &&
         (issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) &&
         (had & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0) {
         ci->i_rdcache_gen++;
     }
 
     /*
      * If FILE_SHARED is newly issued, mark dir not complete. We don't
      * know what happened to this directory while we didn't have the cap.
      * If FILE_SHARED is being revoked, also mark dir not complete. It
      * stops on-going cached readdir.
      */
     if ((issued & CEPH_CAP_FILE_SHARED) != (had & CEPH_CAP_FILE_SHARED)) {
         if (issued & CEPH_CAP_FILE_SHARED)
             atomic_inc(&ci->i_shared_gen);
         if (S_ISDIR(ci->netfs.inode.i_mode)) {
             dout(" marking %p NOT complete\n", &ci->netfs.inode);
             __ceph_dir_clear_complete(ci);
         }
     }
 
     /* Wipe saved layout if we're losing DIR_CREATE caps */
     if (S_ISDIR(ci->netfs.inode.i_mode) && (had & CEPH_CAP_DIR_CREATE) &&
         !(issued & CEPH_CAP_DIR_CREATE)) {
          ceph_put_string(rcu_dereference_raw(ci->i_cached_layout.pool_ns));
          memset(&ci->i_cached_layout, 0, sizeof(ci->i_cached_layout));
     }
 }
 
 /**
  * change_auth_cap_ses - move inode to appropriate lists when auth caps change
  * @ci: inode to be moved
  * @session: new auth caps session
  */
 void change_auth_cap_ses(struct ceph_inode_info *ci,
              struct ceph_mds_session *session)
 {
     lockdep_assert_held(&ci->i_ceph_lock);
 
     if (list_empty(&ci->i_dirty_item) && list_empty(&ci->i_flushing_item))
         return;
 
     spin_lock(&session->s_mdsc->cap_dirty_lock);
     if (!list_empty(&ci->i_dirty_item))
         list_move(&ci->i_dirty_item, &session->s_cap_dirty);
     if (!list_empty(&ci->i_flushing_item))
         list_move_tail(&ci->i_flushing_item, &session->s_cap_flushing);
     spin_unlock(&session->s_mdsc->cap_dirty_lock);
 }
 
 /*
  * Add a capability under the given MDS session.
  *
  * Caller should hold session snap_rwsem (read) and ci->i_ceph_lock
  *
  * @fmode is the open file mode, if we are opening a file, otherwise
  * it is < 0.  (This is so we can atomically add the cap and add an
  * open file reference to it.)
  */
 void ceph_add_cap(struct inode *inode,
           struct ceph_mds_session *session, u64 cap_id,
           unsigned issued, unsigned wanted,
           unsigned seq, unsigned mseq, u64 realmino, int flags,
           struct ceph_cap **new_cap)
 {
     struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_cap *cap;
     int mds = session->s_mds;
     int actual_wanted;
     u32 gen;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("add_cap %p mds%d cap %llx %s seq %d\n", inode,
          session->s_mds, cap_id, ceph_cap_string(issued), seq);
 
     gen = atomic_read(&session->s_cap_gen);
 
     cap = __get_cap_for_mds(ci, mds);
     if (!cap) {
         cap = *new_cap;
         *new_cap = NULL;
 
         cap->issued = 0;
         cap->implemented = 0;
         cap->mds = mds;
         cap->mds_wanted = 0;
         cap->mseq = 0;
 
         cap->ci = ci;
         __insert_cap_node(ci, cap);
 
         /* add to session cap list */
         cap->session = session;
         spin_lock(&session->s_cap_lock);
         list_add_tail(&cap->session_caps, &session->s_caps);
         session->s_nr_caps++;
         atomic64_inc(&mdsc->metric.total_caps);
         spin_unlock(&session->s_cap_lock);
     } else {
         spin_lock(&session->s_cap_lock);
         list_move_tail(&cap->session_caps, &session->s_caps);
         spin_unlock(&session->s_cap_lock);
 
         if (cap->cap_gen < gen)
             cap->issued = cap->implemented = CEPH_CAP_PIN;
 
         /*
          * auth mds of the inode changed. we received the cap export
          * message, but still haven't received the cap import message.
          * handle_cap_export() updated the new auth MDS' cap.
          *
          * "ceph_seq_cmp(seq, cap->seq) <= 0" means we are processing
          * a message that was send before the cap import message. So
          * don't remove caps.
          */
         if (ceph_seq_cmp(seq, cap->seq) <= 0) {
             WARN_ON(cap != ci->i_auth_cap);
             WARN_ON(cap->cap_id != cap_id);
             seq = cap->seq;
             mseq = cap->mseq;
             issued |= cap->issued;
             flags |= CEPH_CAP_FLAG_AUTH;
         }
     }
 
     if (!ci->i_snap_realm ||
         ((flags & CEPH_CAP_FLAG_AUTH) &&
          realmino != (u64)-1 && ci->i_snap_realm->ino != realmino)) {
         /*
          * add this inode to the appropriate snap realm
          */
         struct ceph_snap_realm *realm = ceph_lookup_snap_realm(mdsc,
                                    realmino);
         if (realm)
             ceph_change_snap_realm(inode, realm);
         else
             WARN(1, "%s: couldn't find snap realm 0x%llx (ino 0x%llx oldrealm 0x%llx)\n",
                  __func__, realmino, ci->i_vino.ino,
                  ci->i_snap_realm ? ci->i_snap_realm->ino : 0);
     }
 
     __check_cap_issue(ci, cap, issued);
 
     /*
      * If we are issued caps we don't want, or the mds' wanted
      * value appears to be off, queue a check so we'll release
      * later and/or update the mds wanted value.
      */
     actual_wanted = __ceph_caps_wanted(ci);
     if ((wanted & ~actual_wanted) ||
         (issued & ~actual_wanted & CEPH_CAP_ANY_WR)) {
         dout(" issued %s, mds wanted %s, actual %s, queueing\n",
              ceph_cap_string(issued), ceph_cap_string(wanted),
              ceph_cap_string(actual_wanted));
         __cap_delay_requeue(mdsc, ci);
     }
 
     if (flags & CEPH_CAP_FLAG_AUTH) {
         if (!ci->i_auth_cap ||
             ceph_seq_cmp(ci->i_auth_cap->mseq, mseq) < 0) {
             if (ci->i_auth_cap &&
                 ci->i_auth_cap->session != cap->session)
                 change_auth_cap_ses(ci, cap->session);
             ci->i_auth_cap = cap;
             cap->mds_wanted = wanted;
         }
     } else {
         WARN_ON(ci->i_auth_cap == cap);
     }
 
     dout("add_cap inode %p (%llx.%llx) cap %p %s now %s seq %d mds%d\n",
          inode, ceph_vinop(inode), cap, ceph_cap_string(issued),
          ceph_cap_string(issued|cap->issued), seq, mds);
     cap->cap_id = cap_id;
     cap->issued = issued;
     cap->implemented |= issued;
     if (ceph_seq_cmp(mseq, cap->mseq) > 0)
         cap->mds_wanted = wanted;
     else
         cap->mds_wanted |= wanted;
     cap->seq = seq;
     cap->issue_seq = seq;
     cap->mseq = mseq;
     cap->cap_gen = gen;
 }
 
 /*
  * Return true if cap has not timed out and belongs to the current
  * generation of the MDS session (i.e. has not gone 'stale' due to
  * us losing touch with the mds).
  */
 static int __cap_is_valid(struct ceph_cap *cap)
 {
     unsigned long ttl;
     u32 gen;
 
     gen = atomic_read(&cap->session->s_cap_gen);
     ttl = cap->session->s_cap_ttl;
 
     if (cap->cap_gen < gen || time_after_eq(jiffies, ttl)) {
         dout("__cap_is_valid %p cap %p issued %s "
              "but STALE (gen %u vs %u)\n", &cap->ci->netfs.inode,
              cap, ceph_cap_string(cap->issued), cap->cap_gen, gen);
         return 0;
     }
 
     return 1;
 }
 
 /*
  * Return set of valid cap bits issued to us.  Note that caps time
  * out, and may be invalidated in bulk if the client session times out
  * and session->s_cap_gen is bumped.
  */
 int __ceph_caps_issued(struct ceph_inode_info *ci, int *implemented)
 {
     int have = ci->i_snap_caps;
     struct ceph_cap *cap;
     struct rb_node *p;
 
     if (implemented)
         *implemented = 0;
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         cap = rb_entry(p, struct ceph_cap, ci_node);
         if (!__cap_is_valid(cap))
             continue;
         dout("__ceph_caps_issued %p cap %p issued %s\n",
              &ci->netfs.inode, cap, ceph_cap_string(cap->issued));
         have |= cap->issued;
         if (implemented)
             *implemented |= cap->implemented;
     }
     /*
      * exclude caps issued by non-auth MDS, but are been revoking
      * by the auth MDS. The non-auth MDS should be revoking/exporting
      * these caps, but the message is delayed.
      */
     if (ci->i_auth_cap) {
         cap = ci->i_auth_cap;
         have &= ~cap->implemented | cap->issued;
     }
     return have;
 }
 
 /*
  * Get cap bits issued by caps other than @ocap
  */
 int __ceph_caps_issued_other(struct ceph_inode_info *ci, struct ceph_cap *ocap)
 {
     int have = ci->i_snap_caps;
     struct ceph_cap *cap;
     struct rb_node *p;
 
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         cap = rb_entry(p, struct ceph_cap, ci_node);
         if (cap == ocap)
             continue;
         if (!__cap_is_valid(cap))
             continue;
         have |= cap->issued;
     }
     return have;
 }
 
 /*
  * Move a cap to the end of the LRU (oldest caps at list head, newest
  * at list tail).
  */
 static void __touch_cap(struct ceph_cap *cap)
 {
     struct ceph_mds_session *s = cap->session;
 
     spin_lock(&s->s_cap_lock);
     if (!s->s_cap_iterator) {
         dout("__touch_cap %p cap %p mds%d\n", &cap->ci->netfs.inode, cap,
              s->s_mds);
         list_move_tail(&cap->session_caps, &s->s_caps);
     } else {
         dout("__touch_cap %p cap %p mds%d NOP, iterating over caps\n",
              &cap->ci->netfs.inode, cap, s->s_mds);
     }
     spin_unlock(&s->s_cap_lock);
 }
 
 /*
  * Check if we hold the given mask.  If so, move the cap(s) to the
  * front of their respective LRUs.  (This is the preferred way for
  * callers to check for caps they want.)
  */
 int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
 {
     struct ceph_cap *cap;
     struct rb_node *p;
     int have = ci->i_snap_caps;
 
     if ((have & mask) == mask) {
         dout("__ceph_caps_issued_mask ino 0x%llx snap issued %s"
              " (mask %s)\n", ceph_ino(&ci->netfs.inode),
              ceph_cap_string(have),
              ceph_cap_string(mask));
         return 1;
     }
 
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         cap = rb_entry(p, struct ceph_cap, ci_node);
         if (!__cap_is_valid(cap))
             continue;
         if ((cap->issued & mask) == mask) {
             dout("__ceph_caps_issued_mask ino 0x%llx cap %p issued %s"
                  " (mask %s)\n", ceph_ino(&ci->netfs.inode), cap,
                  ceph_cap_string(cap->issued),
                  ceph_cap_string(mask));
             if (touch)
                 __touch_cap(cap);
             return 1;
         }
 
         /* does a combination of caps satisfy mask? */
         have |= cap->issued;
         if ((have & mask) == mask) {
             dout("__ceph_caps_issued_mask ino 0x%llx combo issued %s"
                  " (mask %s)\n", ceph_ino(&ci->netfs.inode),
                  ceph_cap_string(cap->issued),
                  ceph_cap_string(mask));
             if (touch) {
                 struct rb_node *q;
 
                 /* touch this + preceding caps */
                 __touch_cap(cap);
                 for (q = rb_first(&ci->i_caps); q != p;
                      q = rb_next(q)) {
                     cap = rb_entry(q, struct ceph_cap,
                                ci_node);
                     if (!__cap_is_valid(cap))
                         continue;
                     if (cap->issued & mask)
                         __touch_cap(cap);
                 }
             }
             return 1;
         }
     }
 
     return 0;
 }
 
 int __ceph_caps_issued_mask_metric(struct ceph_inode_info *ci, int mask,
                    int touch)
 {
     struct ceph_fs_client *fsc = ceph_sb_to_client(ci->netfs.inode.i_sb);
     int r;
 
     r = __ceph_caps_issued_mask(ci, mask, touch);
     if (r)
         ceph_update_cap_hit(&fsc->mdsc->metric);
     else
         ceph_update_cap_mis(&fsc->mdsc->metric);
     return r;
 }
 
 /*
  * Return true if mask caps are currently being revoked by an MDS.
  */
 int __ceph_caps_revoking_other(struct ceph_inode_info *ci,
                    struct ceph_cap *ocap, int mask)
 {
     struct ceph_cap *cap;
     struct rb_node *p;
 
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         cap = rb_entry(p, struct ceph_cap, ci_node);
         if (cap != ocap &&
             (cap->implemented & ~cap->issued & mask))
             return 1;
     }
     return 0;
 }
 
 int ceph_caps_revoking(struct ceph_inode_info *ci, int mask)
 {
     struct inode *inode = &ci->netfs.inode;
     int ret;
 
     spin_lock(&ci->i_ceph_lock);
     ret = __ceph_caps_revoking_other(ci, NULL, mask);
     spin_unlock(&ci->i_ceph_lock);
     dout("ceph_caps_revoking %p %s = %d\n", inode,
          ceph_cap_string(mask), ret);
     return ret;
 }
 
 int __ceph_caps_used(struct ceph_inode_info *ci)
 {
     int used = 0;
     if (ci->i_pin_ref)
         used |= CEPH_CAP_PIN;
     if (ci->i_rd_ref)
         used |= CEPH_CAP_FILE_RD;
     if (ci->i_rdcache_ref ||
         (S_ISREG(ci->netfs.inode.i_mode) &&
          ci->netfs.inode.i_data.nrpages))
         used |= CEPH_CAP_FILE_CACHE;
     if (ci->i_wr_ref)
         used |= CEPH_CAP_FILE_WR;
     if (ci->i_wb_ref || ci->i_wrbuffer_ref)
         used |= CEPH_CAP_FILE_BUFFER;
     if (ci->i_fx_ref)
         used |= CEPH_CAP_FILE_EXCL;
     return used;
 }
 
 #define FMODE_WAIT_BIAS 1000
 
 /*
  * wanted, by virtue of open file modes
  */
 int __ceph_caps_file_wanted(struct ceph_inode_info *ci)
 {
     const int PIN_SHIFT = ffs(CEPH_FILE_MODE_PIN);
     const int RD_SHIFT = ffs(CEPH_FILE_MODE_RD);
     const int WR_SHIFT = ffs(CEPH_FILE_MODE_WR);
     const int LAZY_SHIFT = ffs(CEPH_FILE_MODE_LAZY);
     struct ceph_mount_options *opt =
         ceph_inode_to_client(&ci->netfs.inode)->mount_options;
     unsigned long used_cutoff = jiffies - opt->caps_wanted_delay_max * HZ;
     unsigned long idle_cutoff = jiffies - opt->caps_wanted_delay_min * HZ;
 
     if (S_ISDIR(ci->netfs.inode.i_mode)) {
         int want = 0;
 
         /* use used_cutoff here, to keep dir's wanted caps longer */
         if (ci->i_nr_by_mode[RD_SHIFT] > 0 ||
             time_after(ci->i_last_rd, used_cutoff))
             want |= CEPH_CAP_ANY_SHARED;
 
         if (ci->i_nr_by_mode[WR_SHIFT] > 0 ||
             time_after(ci->i_last_wr, used_cutoff)) {
             want |= CEPH_CAP_ANY_SHARED | CEPH_CAP_FILE_EXCL;
             if (opt->flags & CEPH_MOUNT_OPT_ASYNC_DIROPS)
                 want |= CEPH_CAP_ANY_DIR_OPS;
         }
 
         if (want || ci->i_nr_by_mode[PIN_SHIFT] > 0)
             want |= CEPH_CAP_PIN;
 
         return want;
     } else {
         int bits = 0;
 
         if (ci->i_nr_by_mode[RD_SHIFT] > 0) {
             if (ci->i_nr_by_mode[RD_SHIFT] >= FMODE_WAIT_BIAS ||
                 time_after(ci->i_last_rd, used_cutoff))
                 bits |= 1 << RD_SHIFT;
         } else if (time_after(ci->i_last_rd, idle_cutoff)) {
             bits |= 1 << RD_SHIFT;
         }
 
         if (ci->i_nr_by_mode[WR_SHIFT] > 0) {
             if (ci->i_nr_by_mode[WR_SHIFT] >= FMODE_WAIT_BIAS ||
                 time_after(ci->i_last_wr, used_cutoff))
                 bits |= 1 << WR_SHIFT;
         } else if (time_after(ci->i_last_wr, idle_cutoff)) {
             bits |= 1 << WR_SHIFT;
         }
 
         /* check lazyio only when read/write is wanted */
         if ((bits & (CEPH_FILE_MODE_RDWR << 1)) &&
             ci->i_nr_by_mode[LAZY_SHIFT] > 0)
             bits |= 1 << LAZY_SHIFT;
 
         return bits ? ceph_caps_for_mode(bits >> 1) : 0;
     }
 }
 
 /*
  * wanted, by virtue of open file modes AND cap refs (buffered/cached data)
  */
 int __ceph_caps_wanted(struct ceph_inode_info *ci)
 {
     int w = __ceph_caps_file_wanted(ci) | __ceph_caps_used(ci);
     if (S_ISDIR(ci->netfs.inode.i_mode)) {
         /* we want EXCL if holding caps of dir ops */
         if (w & CEPH_CAP_ANY_DIR_OPS)
             w |= CEPH_CAP_FILE_EXCL;
     } else {
         /* we want EXCL if dirty data */
         if (w & CEPH_CAP_FILE_BUFFER)
             w |= CEPH_CAP_FILE_EXCL;
     }
     return w;
 }
 
 /*
  * Return caps we have registered with the MDS(s) as 'wanted'.
  */
 int __ceph_caps_mds_wanted(struct ceph_inode_info *ci, bool check)
 {
     struct ceph_cap *cap;
     struct rb_node *p;
     int mds_wanted = 0;
 
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         cap = rb_entry(p, struct ceph_cap, ci_node);
         if (check && !__cap_is_valid(cap))
             continue;
         if (cap == ci->i_auth_cap)
             mds_wanted |= cap->mds_wanted;
         else
             mds_wanted |= (cap->mds_wanted & ~CEPH_CAP_ANY_FILE_WR);
     }
     return mds_wanted;
 }
 
 int ceph_is_any_caps(struct inode *inode)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int ret;
 
     spin_lock(&ci->i_ceph_lock);
     ret = __ceph_is_any_real_caps(ci);
     spin_unlock(&ci->i_ceph_lock);
 
     return ret;
 }
 
 /*
  * Remove a cap.  Take steps to deal with a racing iterate_session_caps.
  *
  * caller should hold i_ceph_lock.
  * caller will not hold session s_mutex if called from destroy_inode.
  */
 void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
 {
     struct ceph_mds_session *session = cap->session;
     struct ceph_inode_info *ci = cap->ci;
     struct ceph_mds_client *mdsc;
     int removed = 0;
 
     /* 'ci' being NULL means the remove have already occurred */
     if (!ci) {
         dout("%s: cap inode is NULL\n", __func__);
         return;
     }
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("__ceph_remove_cap %p from %p\n", cap, &ci->netfs.inode);
 
     mdsc = ceph_inode_to_client(&ci->netfs.inode)->mdsc;
 
     /* remove from inode's cap rbtree, and clear auth cap */
     rb_erase(&cap->ci_node, &ci->i_caps);
     if (ci->i_auth_cap == cap)
         ci->i_auth_cap = NULL;
 
     /* remove from session list */
     spin_lock(&session->s_cap_lock);
     if (session->s_cap_iterator == cap) {
         /* not yet, we are iterating over this very cap */
         dout("__ceph_remove_cap  delaying %p removal from session %p\n",
              cap, cap->session);
     } else {
         list_del_init(&cap->session_caps);
         session->s_nr_caps--;
         atomic64_dec(&mdsc->metric.total_caps);
         cap->session = NULL;
         removed = 1;
     }
     /* protect backpointer with s_cap_lock: see iterate_session_caps */
     cap->ci = NULL;
 
     /*
      * s_cap_reconnect is protected by s_cap_lock. no one changes
      * s_cap_gen while session is in the reconnect state.
      */
     if (queue_release &&
         (!session->s_cap_reconnect ||
          cap->cap_gen == atomic_read(&session->s_cap_gen))) {
         cap->queue_release = 1;
         if (removed) {
             __ceph_queue_cap_release(session, cap);
             removed = 0;
         }
     } else {
         cap->queue_release = 0;
     }
     cap->cap_ino = ci->i_vino.ino;
 
     spin_unlock(&session->s_cap_lock);
 
     if (removed)
         ceph_put_cap(mdsc, cap);
 
     if (!__ceph_is_any_real_caps(ci)) {
         /* when reconnect denied, we remove session caps forcibly,
          * i_wr_ref can be non-zero. If there are ongoing write,
          * keep i_snap_realm.
          */
         if (ci->i_wr_ref == 0 && ci->i_snap_realm)
             ceph_change_snap_realm(&ci->netfs.inode, NULL);
 
         __cap_delay_cancel(mdsc, ci);
     }
 }
 
 void ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
 {
     struct ceph_inode_info *ci = cap->ci;
     struct ceph_fs_client *fsc;
 
     /* 'ci' being NULL means the remove have already occurred */
     if (!ci) {
         dout("%s: cap inode is NULL\n", __func__);
         return;
     }
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     fsc = ceph_inode_to_client(&ci->netfs.inode);
     WARN_ON_ONCE(ci->i_auth_cap == cap &&
              !list_empty(&ci->i_dirty_item) &&
              !fsc->blocklisted &&
              !ceph_inode_is_shutdown(&ci->netfs.inode));
 
     __ceph_remove_cap(cap, queue_release);
 }
 
 struct cap_msg_args {
     struct ceph_mds_session *session;
     u64         ino, cid, follows;
     u64         flush_tid, oldest_flush_tid, size, max_size;
     u64         xattr_version;
     u64         change_attr;
     struct ceph_buffer  *xattr_buf;
     struct ceph_buffer  *old_xattr_buf;
     struct timespec64   atime, mtime, ctime, btime;
     int         op, caps, wanted, dirty;
     u32         seq, issue_seq, mseq, time_warp_seq;
     u32         flags;
     kuid_t          uid;
     kgid_t          gid;
     umode_t         mode;
     bool            inline_data;
     bool            wake;
 };
 
 /*
  * cap struct size + flock buffer size + inline version + inline data size +
  * osd_epoch_barrier + oldest_flush_tid
  */
 #define CAP_MSG_SIZE (sizeof(struct ceph_mds_caps) + \
               4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4)
 
 /* Marshal up the cap msg to the MDS */
 static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
 {
     struct ceph_mds_caps *fc;
     void *p;
     struct ceph_osd_client *osdc = &arg->session->s_mdsc->fsc->client->osdc;
 
     dout("%s %s %llx %llx caps %s wanted %s dirty %s seq %u/%u tid %llu/%llu mseq %u follows %lld size %llu/%llu xattr_ver %llu xattr_len %d\n",
          __func__, ceph_cap_op_name(arg->op), arg->cid, arg->ino,
          ceph_cap_string(arg->caps), ceph_cap_string(arg->wanted),
          ceph_cap_string(arg->dirty), arg->seq, arg->issue_seq,
          arg->flush_tid, arg->oldest_flush_tid, arg->mseq, arg->follows,
          arg->size, arg->max_size, arg->xattr_version,
          arg->xattr_buf ? (int)arg->xattr_buf->vec.iov_len : 0);
 
     msg->hdr.version = cpu_to_le16(10);
     msg->hdr.tid = cpu_to_le64(arg->flush_tid);
 
     fc = msg->front.iov_base;
     memset(fc, 0, sizeof(*fc));
 
     fc->cap_id = cpu_to_le64(arg->cid);
     fc->op = cpu_to_le32(arg->op);
     fc->seq = cpu_to_le32(arg->seq);
     fc->issue_seq = cpu_to_le32(arg->issue_seq);
     fc->migrate_seq = cpu_to_le32(arg->mseq);
     fc->caps = cpu_to_le32(arg->caps);
     fc->wanted = cpu_to_le32(arg->wanted);
     fc->dirty = cpu_to_le32(arg->dirty);
     fc->ino = cpu_to_le64(arg->ino);
     fc->snap_follows = cpu_to_le64(arg->follows);
 
     fc->size = cpu_to_le64(arg->size);
     fc->max_size = cpu_to_le64(arg->max_size);
     ceph_encode_timespec64(&fc->mtime, &arg->mtime);
     ceph_encode_timespec64(&fc->atime, &arg->atime);
     ceph_encode_timespec64(&fc->ctime, &arg->ctime);
     fc->time_warp_seq = cpu_to_le32(arg->time_warp_seq);
 
     fc->uid = cpu_to_le32(from_kuid(&init_user_ns, arg->uid));
     fc->gid = cpu_to_le32(from_kgid(&init_user_ns, arg->gid));
     fc->mode = cpu_to_le32(arg->mode);
 
     fc->xattr_version = cpu_to_le64(arg->xattr_version);
     if (arg->xattr_buf) {
         msg->middle = ceph_buffer_get(arg->xattr_buf);
         fc->xattr_len = cpu_to_le32(arg->xattr_buf->vec.iov_len);
         msg->hdr.middle_len = cpu_to_le32(arg->xattr_buf->vec.iov_len);
     }
 
     p = fc + 1;
     /* flock buffer size (version 2) */
     ceph_encode_32(&p, 0);
     /* inline version (version 4) */
     ceph_encode_64(&p, arg->inline_data ? 0 : CEPH_INLINE_NONE);
     /* inline data size */
     ceph_encode_32(&p, 0);
     /*
      * osd_epoch_barrier (version 5)
      * The epoch_barrier is protected osdc->lock, so READ_ONCE here in
      * case it was recently changed
      */
     ceph_encode_32(&p, READ_ONCE(osdc->epoch_barrier));
     /* oldest_flush_tid (version 6) */
     ceph_encode_64(&p, arg->oldest_flush_tid);
 
     /*
      * caller_uid/caller_gid (version 7)
      *
      * Currently, we don't properly track which caller dirtied the caps
      * last, and force a flush of them when there is a conflict. For now,
      * just set this to 0:0, to emulate how the MDS has worked up to now.
      */
     ceph_encode_32(&p, 0);
     ceph_encode_32(&p, 0);
 
     /* pool namespace (version 8) (mds always ignores this) */
     ceph_encode_32(&p, 0);
 
     /* btime and change_attr (version 9) */
     ceph_encode_timespec64(p, &arg->btime);
     p += sizeof(struct ceph_timespec);
     ceph_encode_64(&p, arg->change_attr);
 
     /* Advisory flags (version 10) */
     ceph_encode_32(&p, arg->flags);
 }
 
 /*
  * Queue cap releases when an inode is dropped from our cache.
  */
 void __ceph_remove_caps(struct ceph_inode_info *ci)
 {
     struct rb_node *p;
 
     /* lock i_ceph_lock, because ceph_d_revalidate(..., LOOKUP_RCU)
      * may call __ceph_caps_issued_mask() on a freeing inode. */
     spin_lock(&ci->i_ceph_lock);
     p = rb_first(&ci->i_caps);
     while (p) {
         struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
         p = rb_next(p);
         ceph_remove_cap(cap, true);
     }
     spin_unlock(&ci->i_ceph_lock);
 }
 
 /*
  * Prepare to send a cap message to an MDS. Update the cap state, and populate
  * the arg struct with the parameters that will need to be sent. This should
  * be done under the i_ceph_lock to guard against changes to cap state.
  *
  * Make note of max_size reported/requested from mds, revoked caps
  * that have now been implemented.
  */
 static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
                int op, int flags, int used, int want, int retain,
                int flushing, u64 flush_tid, u64 oldest_flush_tid)
 {
     struct ceph_inode_info *ci = cap->ci;
     struct inode *inode = &ci->netfs.inode;
     int held, revoking;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     held = cap->issued | cap->implemented;
     revoking = cap->implemented & ~cap->issued;
     retain &= ~revoking;
 
     dout("%s %p cap %p session %p %s -> %s (revoking %s)\n",
          __func__, inode, cap, cap->session,
          ceph_cap_string(held), ceph_cap_string(held & retain),
          ceph_cap_string(revoking));
     BUG_ON((retain & CEPH_CAP_PIN) == 0);
 
     ci->i_ceph_flags &= ~CEPH_I_FLUSH;
 
     cap->issued &= retain;  /* drop bits we don't want */
     /*
      * Wake up any waiters on wanted -> needed transition. This is due to
      * the weird transition from buffered to sync IO... we need to flush
      * dirty pages _before_ allowing sync writes to avoid reordering.
      */
     arg->wake = cap->implemented & ~cap->issued;
     cap->implemented &= cap->issued | used;
     cap->mds_wanted = want;
 
     arg->session = cap->session;
     arg->ino = ceph_vino(inode).ino;
     arg->cid = cap->cap_id;
     arg->follows = flushing ? ci->i_head_snapc->seq : 0;
     arg->flush_tid = flush_tid;
     arg->oldest_flush_tid = oldest_flush_tid;
 
     arg->size = i_size_read(inode);
     ci->i_reported_size = arg->size;
     arg->max_size = ci->i_wanted_max_size;
     if (cap == ci->i_auth_cap) {
         if (want & CEPH_CAP_ANY_FILE_WR)
             ci->i_requested_max_size = arg->max_size;
         else
             ci->i_requested_max_size = 0;
     }
 
     if (flushing & CEPH_CAP_XATTR_EXCL) {
         arg->old_xattr_buf = __ceph_build_xattrs_blob(ci);
         arg->xattr_version = ci->i_xattrs.version;
         arg->xattr_buf = ci->i_xattrs.blob;
     } else {
         arg->xattr_buf = NULL;
         arg->old_xattr_buf = NULL;
     }
 
     arg->mtime = inode->i_mtime;
     arg->atime = inode->i_atime;
     arg->ctime = inode->i_ctime;
     arg->btime = ci->i_btime;
     arg->change_attr = inode_peek_iversion_raw(inode);
 
     arg->op = op;
     arg->caps = cap->implemented;
     arg->wanted = want;
     arg->dirty = flushing;
 
     arg->seq = cap->seq;
     arg->issue_seq = cap->issue_seq;
     arg->mseq = cap->mseq;
     arg->time_warp_seq = ci->i_time_warp_seq;
 
     arg->uid = inode->i_uid;
     arg->gid = inode->i_gid;
     arg->mode = inode->i_mode;
 
     arg->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
     if (!(flags & CEPH_CLIENT_CAPS_PENDING_CAPSNAP) &&
         !list_empty(&ci->i_cap_snaps)) {
         struct ceph_cap_snap *capsnap;
         list_for_each_entry_reverse(capsnap, &ci->i_cap_snaps, ci_item) {
             if (capsnap->cap_flush.tid)
                 break;
             if (capsnap->need_flush) {
                 flags |= CEPH_CLIENT_CAPS_PENDING_CAPSNAP;
                 break;
             }
         }
     }
     arg->flags = flags;
 }
 
 /*
  * Send a cap msg on the given inode.
  *
  * Caller should hold snap_rwsem (read), s_mutex.
  */
 static void __send_cap(struct cap_msg_args *arg, struct ceph_inode_info *ci)
 {
     struct ceph_msg *msg;
     struct inode *inode = &ci->netfs.inode;
 
     msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, CAP_MSG_SIZE, GFP_NOFS, false);
     if (!msg) {
         pr_err("error allocating cap msg: ino (%llx.%llx) flushing %s tid %llu, requeuing cap.\n",
                ceph_vinop(inode), ceph_cap_string(arg->dirty),
                arg->flush_tid);
         spin_lock(&ci->i_ceph_lock);
         __cap_delay_requeue(arg->session->s_mdsc, ci);
         spin_unlock(&ci->i_ceph_lock);
         return;
     }
 
     encode_cap_msg(msg, arg);
     ceph_con_send(&arg->session->s_con, msg);
     ceph_buffer_put(arg->old_xattr_buf);
     if (arg->wake)
         wake_up_all(&ci->i_cap_wq);
 }
 
 static inline int __send_flush_snap(struct inode *inode,
                     struct ceph_mds_session *session,
                     struct ceph_cap_snap *capsnap,
                     u32 mseq, u64 oldest_flush_tid)
 {
     struct cap_msg_args arg;
     struct ceph_msg     *msg;
 
     msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, CAP_MSG_SIZE, GFP_NOFS, false);
     if (!msg)
         return -ENOMEM;
 
     arg.session = session;
     arg.ino = ceph_vino(inode).ino;
     arg.cid = 0;
     arg.follows = capsnap->follows;
     arg.flush_tid = capsnap->cap_flush.tid;
     arg.oldest_flush_tid = oldest_flush_tid;
 
     arg.size = capsnap->size;
     arg.max_size = 0;
     arg.xattr_version = capsnap->xattr_version;
     arg.xattr_buf = capsnap->xattr_blob;
     arg.old_xattr_buf = NULL;
 
     arg.atime = capsnap->atime;
     arg.mtime = capsnap->mtime;
     arg.ctime = capsnap->ctime;
     arg.btime = capsnap->btime;
     arg.change_attr = capsnap->change_attr;
 
     arg.op = CEPH_CAP_OP_FLUSHSNAP;
     arg.caps = capsnap->issued;
     arg.wanted = 0;
     arg.dirty = capsnap->dirty;
 
     arg.seq = 0;
     arg.issue_seq = 0;
     arg.mseq = mseq;
     arg.time_warp_seq = capsnap->time_warp_seq;
 
     arg.uid = capsnap->uid;
     arg.gid = capsnap->gid;
     arg.mode = capsnap->mode;
 
     arg.inline_data = capsnap->inline_data;
     arg.flags = 0;
     arg.wake = false;
 
     encode_cap_msg(msg, &arg);
     ceph_con_send(&arg.session->s_con, msg);
     return 0;
 }
 
 /*
  * When a snapshot is taken, clients accumulate dirty metadata on
  * inodes with capabilities in ceph_cap_snaps to describe the file
  * state at the time the snapshot was taken.  This must be flushed
  * asynchronously back to the MDS once sync writes complete and dirty
  * data is written out.
  *
  * Called under i_ceph_lock.
  */
 static void __ceph_flush_snaps(struct ceph_inode_info *ci,
                    struct ceph_mds_session *session)
         __releases(ci->i_ceph_lock)
         __acquires(ci->i_ceph_lock)
 {
     struct inode *inode = &ci->netfs.inode;
     struct ceph_mds_client *mdsc = session->s_mdsc;
     struct ceph_cap_snap *capsnap;
     u64 oldest_flush_tid = 0;
     u64 first_tid = 1, last_tid = 0;
 
     dout("__flush_snaps %p session %p\n", inode, session);
 
     list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
         /*
          * we need to wait for sync writes to complete and for dirty
          * pages to be written out.
          */
         if (capsnap->dirty_pages || capsnap->writing)
             break;
 
         /* should be removed by ceph_try_drop_cap_snap() */
         BUG_ON(!capsnap->need_flush);
 
         /* only flush each capsnap once */
         if (capsnap->cap_flush.tid > 0) {
             dout(" already flushed %p, skipping\n", capsnap);
             continue;
         }
 
         spin_lock(&mdsc->cap_dirty_lock);
         capsnap->cap_flush.tid = ++mdsc->last_cap_flush_tid;
         list_add_tail(&capsnap->cap_flush.g_list,
                   &mdsc->cap_flush_list);
         if (oldest_flush_tid == 0)
             oldest_flush_tid = __get_oldest_flush_tid(mdsc);
         if (list_empty(&ci->i_flushing_item)) {
             list_add_tail(&ci->i_flushing_item,
                       &session->s_cap_flushing);
         }
         spin_unlock(&mdsc->cap_dirty_lock);
 
         list_add_tail(&capsnap->cap_flush.i_list,
                   &ci->i_cap_flush_list);
 
         if (first_tid == 1)
             first_tid = capsnap->cap_flush.tid;
         last_tid = capsnap->cap_flush.tid;
     }
 
     ci->i_ceph_flags &= ~CEPH_I_FLUSH_SNAPS;
 
     while (first_tid <= last_tid) {
         struct ceph_cap *cap = ci->i_auth_cap;
         struct ceph_cap_flush *cf = NULL, *iter;
         int ret;
 
         if (!(cap && cap->session == session)) {
             dout("__flush_snaps %p auth cap %p not mds%d, "
                  "stop\n", inode, cap, session->s_mds);
             break;
         }
 
         ret = -ENOENT;
         list_for_each_entry(iter, &ci->i_cap_flush_list, i_list) {
             if (iter->tid >= first_tid) {
                 cf = iter;
                 ret = 0;
                 break;
             }
         }
         if (ret < 0)
             break;
 
         first_tid = cf->tid + 1;
 
         capsnap = container_of(cf, struct ceph_cap_snap, cap_flush);
         refcount_inc(&capsnap->nref);
         spin_unlock(&ci->i_ceph_lock);
 
         dout("__flush_snaps %p capsnap %p tid %llu %s\n",
              inode, capsnap, cf->tid, ceph_cap_string(capsnap->dirty));
 
         ret = __send_flush_snap(inode, session, capsnap, cap->mseq,
                     oldest_flush_tid);
         if (ret < 0) {
             pr_err("__flush_snaps: error sending cap flushsnap, "
                    "ino (%llx.%llx) tid %llu follows %llu\n",
                 ceph_vinop(inode), cf->tid, capsnap->follows);
         }
 
         ceph_put_cap_snap(capsnap);
         spin_lock(&ci->i_ceph_lock);
     }
 }
 
 void ceph_flush_snaps(struct ceph_inode_info *ci,
               struct ceph_mds_session **psession)
 {
     struct inode *inode = &ci->netfs.inode;
     struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
     struct ceph_mds_session *session = NULL;
     int mds;
 
     dout("ceph_flush_snaps %p\n", inode);
     if (psession)
         session = *psession;
 retry:
     spin_lock(&ci->i_ceph_lock);
     if (!(ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)) {
         dout(" no capsnap needs flush, doing nothing\n");
         goto out;
     }
     if (!ci->i_auth_cap) {
         dout(" no auth cap (migrating?), doing nothing\n");
         goto out;
     }
 
     mds = ci->i_auth_cap->session->s_mds;
     if (session && session->s_mds != mds) {
         dout(" oops, wrong session %p mutex\n", session);
         ceph_put_mds_session(session);
         session = NULL;
     }
     if (!session) {
         spin_unlock(&ci->i_ceph_lock);
         mutex_lock(&mdsc->mutex);
         session = __ceph_lookup_mds_session(mdsc, mds);
         mutex_unlock(&mdsc->mutex);
         goto retry;
     }
 
     // make sure flushsnap messages are sent in proper order.
     if (ci->i_ceph_flags & CEPH_I_KICK_FLUSH)
         __kick_flushing_caps(mdsc, session, ci, 0);
 
     __ceph_flush_snaps(ci, session);
 out:
     spin_unlock(&ci->i_ceph_lock);
 
     if (psession)
         *psession = session;
     else
         ceph_put_mds_session(session);
     /* we flushed them all; remove this inode from the queue */
     spin_lock(&mdsc->snap_flush_lock);
     list_del_init(&ci->i_snap_flush_item);
     spin_unlock(&mdsc->snap_flush_lock);
 }
 
 /*
  * Mark caps dirty.  If inode is newly dirty, return the dirty flags.
  * Caller is then responsible for calling __mark_inode_dirty with the
  * returned flags value.
  */
 int __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask,
                struct ceph_cap_flush **pcf)
 {
     struct ceph_mds_client *mdsc =
         ceph_sb_to_client(ci->netfs.inode.i_sb)->mdsc;
     struct inode *inode = &ci->netfs.inode;
     int was = ci->i_dirty_caps;
     int dirty = 0;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     if (!ci->i_auth_cap) {
         pr_warn("__mark_dirty_caps %p %llx mask %s, "
             "but no auth cap (session was closed?)\n",
             inode, ceph_ino(inode), ceph_cap_string(mask));
         return 0;
     }
 
     dout("__mark_dirty_caps %p %s dirty %s -> %s\n", &ci->netfs.inode,
          ceph_cap_string(mask), ceph_cap_string(was),
          ceph_cap_string(was | mask));
     ci->i_dirty_caps |= mask;
     if (was == 0) {
         struct ceph_mds_session *session = ci->i_auth_cap->session;
 
         WARN_ON_ONCE(ci->i_prealloc_cap_flush);
         swap(ci->i_prealloc_cap_flush, *pcf);
 
         if (!ci->i_head_snapc) {
             WARN_ON_ONCE(!rwsem_is_locked(&mdsc->snap_rwsem));
             ci->i_head_snapc = ceph_get_snap_context(
                 ci->i_snap_realm->cached_context);
         }
         dout(" inode %p now dirty snapc %p auth cap %p\n",
              &ci->netfs.inode, ci->i_head_snapc, ci->i_auth_cap);
         BUG_ON(!list_empty(&ci->i_dirty_item));
         spin_lock(&mdsc->cap_dirty_lock);
         list_add(&ci->i_dirty_item, &session->s_cap_dirty);
         spin_unlock(&mdsc->cap_dirty_lock);
         if (ci->i_flushing_caps == 0) {
             ihold(inode);
             dirty |= I_DIRTY_SYNC;
         }
     } else {
         WARN_ON_ONCE(!ci->i_prealloc_cap_flush);
     }
     BUG_ON(list_empty(&ci->i_dirty_item));
     if (((was | ci->i_flushing_caps) & CEPH_CAP_FILE_BUFFER) &&
         (mask & CEPH_CAP_FILE_BUFFER))
         dirty |= I_DIRTY_DATASYNC;
     __cap_delay_requeue(mdsc, ci);
     return dirty;
 }
 
 struct ceph_cap_flush *ceph_alloc_cap_flush(void)
 {
     struct ceph_cap_flush *cf;
 
     cf = kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL);
     if (!cf)
         return NULL;
 
     cf->is_capsnap = false;
     return cf;
 }
 
 void ceph_free_cap_flush(struct ceph_cap_flush *cf)
 {
     if (cf)
         kmem_cache_free(ceph_cap_flush_cachep, cf);
 }
 
 static u64 __get_oldest_flush_tid(struct ceph_mds_client *mdsc)
 {
     if (!list_empty(&mdsc->cap_flush_list)) {
         struct ceph_cap_flush *cf =
             list_first_entry(&mdsc->cap_flush_list,
                      struct ceph_cap_flush, g_list);
         return cf->tid;
     }
     return 0;
 }
 
 /*
  * Remove cap_flush from the mdsc's or inode's flushing cap list.
  * Return true if caller needs to wake up flush waiters.
  */
 static bool __detach_cap_flush_from_mdsc(struct ceph_mds_client *mdsc,
                      struct ceph_cap_flush *cf)
 {
     struct ceph_cap_flush *prev;
     bool wake = cf->wake;
 
     if (wake && cf->g_list.prev != &mdsc->cap_flush_list) {
         prev = list_prev_entry(cf, g_list);
         prev->wake = true;
         wake = false;
     }
     list_del_init(&cf->g_list);
     return wake;
 }
 
 static bool __detach_cap_flush_from_ci(struct ceph_inode_info *ci,
                        struct ceph_cap_flush *cf)
 {
     struct ceph_cap_flush *prev;
     bool wake = cf->wake;
 
     if (wake && cf->i_list.prev != &ci->i_cap_flush_list) {
         prev = list_prev_entry(cf, i_list);
         prev->wake = true;
         wake = false;
     }
     list_del_init(&cf->i_list);
     return wake;
 }
 
 /*
  * Add dirty inode to the flushing list.  Assigned a seq number so we
  * can wait for caps to flush without starving.
  *
  * Called under i_ceph_lock. Returns the flush tid.
  */
 static u64 __mark_caps_flushing(struct inode *inode,
                 struct ceph_mds_session *session, bool wake,
                 u64 *oldest_flush_tid)
 {
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_cap_flush *cf = NULL;
     int flushing;
 
     lockdep_assert_held(&ci->i_ceph_lock);
     BUG_ON(ci->i_dirty_caps == 0);
     BUG_ON(list_empty(&ci->i_dirty_item));
     BUG_ON(!ci->i_prealloc_cap_flush);
 
     flushing = ci->i_dirty_caps;
     dout("__mark_caps_flushing flushing %s, flushing_caps %s -> %s\n",
          ceph_cap_string(flushing),
          ceph_cap_string(ci->i_flushing_caps),
          ceph_cap_string(ci->i_flushing_caps | flushing));
     ci->i_flushing_caps |= flushing;
     ci->i_dirty_caps = 0;
     dout(" inode %p now !dirty\n", inode);
 
     swap(cf, ci->i_prealloc_cap_flush);
     cf->caps = flushing;
     cf->wake = wake;
 
     spin_lock(&mdsc->cap_dirty_lock);
     list_del_init(&ci->i_dirty_item);
 
     cf->tid = ++mdsc->last_cap_flush_tid;
     list_add_tail(&cf->g_list, &mdsc->cap_flush_list);
     *oldest_flush_tid = __get_oldest_flush_tid(mdsc);
 
     if (list_empty(&ci->i_flushing_item)) {
         list_add_tail(&ci->i_flushing_item, &session->s_cap_flushing);
         mdsc->num_cap_flushing++;
     }
     spin_unlock(&mdsc->cap_dirty_lock);
 
     list_add_tail(&cf->i_list, &ci->i_cap_flush_list);
 
     return cf->tid;
 }
 
 /*
  * try to invalidate mapping pages without blocking.
  */
 static int try_nonblocking_invalidate(struct inode *inode)
     __releases(ci->i_ceph_lock)
     __acquires(ci->i_ceph_lock)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     u32 invalidating_gen = ci->i_rdcache_gen;
 
     spin_unlock(&ci->i_ceph_lock);
     ceph_fscache_invalidate(inode, false);
     invalidate_mapping_pages(&inode->i_data, 0, -1);
     spin_lock(&ci->i_ceph_lock);
 
     if (inode->i_data.nrpages == 0 &&
         invalidating_gen == ci->i_rdcache_gen) {
         /* success. */
         dout("try_nonblocking_invalidate %p success\n", inode);
         /* save any racing async invalidate some trouble */
         ci->i_rdcache_revoking = ci->i_rdcache_gen - 1;
         return 0;
     }
     dout("try_nonblocking_invalidate %p failed\n", inode);
     return -1;
 }
 
 bool __ceph_should_report_size(struct ceph_inode_info *ci)
 {
     loff_t size = i_size_read(&ci->netfs.inode);
     /* mds will adjust max size according to the reported size */
     if (ci->i_flushing_caps & CEPH_CAP_FILE_WR)
         return false;
     if (size >= ci->i_max_size)
         return true;
     /* half of previous max_size increment has been used */
     if (ci->i_max_size > ci->i_reported_size &&
         (size << 1) >= ci->i_max_size + ci->i_reported_size)
         return true;
     return false;
 }
 
 /*
  * Swiss army knife function to examine currently used and wanted
  * versus held caps.  Release, flush, ack revoked caps to mds as
  * appropriate.
  *
  *  CHECK_CAPS_AUTHONLY - we should only check the auth cap
  *  CHECK_CAPS_FLUSH - we should flush any dirty caps immediately, without
  *    further delay.
  */
 void ceph_check_caps(struct ceph_inode_info *ci, int flags,
              struct ceph_mds_session *session)
 {
     struct inode *inode = &ci->netfs.inode;
     struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
     struct ceph_cap *cap;
     u64 flush_tid, oldest_flush_tid;
     int file_wanted, used, cap_used;
     int issued, implemented, want, retain, revoking, flushing = 0;
     int mds = -1;   /* keep track of how far we've gone through i_caps list
                to avoid an infinite loop on retry */
     struct rb_node *p;
     bool queue_invalidate = false;
     bool tried_invalidate = false;
     bool queue_writeback = false;
 
     if (session)
         ceph_get_mds_session(session);
 
     spin_lock(&ci->i_ceph_lock);
     if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE) {
         /* Don't send messages until we get async create reply */
         spin_unlock(&ci->i_ceph_lock);
         ceph_put_mds_session(session);
         return;
     }
 
     if (ci->i_ceph_flags & CEPH_I_FLUSH)
         flags |= CHECK_CAPS_FLUSH;
 retry:
     /* Caps wanted by virtue of active open files. */
     file_wanted = __ceph_caps_file_wanted(ci);
 
     /* Caps which have active references against them */
     used = __ceph_caps_used(ci);
 
     /*
      * "issued" represents the current caps that the MDS wants us to have.
      * "implemented" is the set that we have been granted, and includes the
      * ones that have not yet been returned to the MDS (the "revoking" set,
      * usually because they have outstanding references).
      */
     issued = __ceph_caps_issued(ci, &implemented);
     revoking = implemented & ~issued;
 
     want = file_wanted;
 
     /* The ones we currently want to retain (may be adjusted below) */
     retain = file_wanted | used | CEPH_CAP_PIN;
     if (!mdsc->stopping && inode->i_nlink > 0) {
         if (file_wanted) {
             retain |= CEPH_CAP_ANY;       /* be greedy */
         } else if (S_ISDIR(inode->i_mode) &&
                (issued & CEPH_CAP_FILE_SHARED) &&
                __ceph_dir_is_complete(ci)) {
             /*
              * If a directory is complete, we want to keep
              * the exclusive cap. So that MDS does not end up
              * revoking the shared cap on every create/unlink
              * operation.
              */
             if (IS_RDONLY(inode)) {
                 want = CEPH_CAP_ANY_SHARED;
             } else {
                 want |= CEPH_CAP_ANY_SHARED | CEPH_CAP_FILE_EXCL;
             }
             retain |= want;
         } else {
 
             retain |= CEPH_CAP_ANY_SHARED;
             /*
              * keep RD only if we didn't have the file open RW,
              * because then the mds would revoke it anyway to
              * journal max_size=0.
              */
             if (ci->i_max_size == 0)
                 retain |= CEPH_CAP_ANY_RD;
         }
     }
 
     dout("check_caps %llx.%llx file_want %s used %s dirty %s flushing %s"
          " issued %s revoking %s retain %s %s%s%s\n", ceph_vinop(inode),
          ceph_cap_string(file_wanted),
          ceph_cap_string(used), ceph_cap_string(ci->i_dirty_caps),
          ceph_cap_string(ci->i_flushing_caps),
          ceph_cap_string(issued), ceph_cap_string(revoking),
          ceph_cap_string(retain),
          (flags & CHECK_CAPS_AUTHONLY) ? " AUTHONLY" : "",
          (flags & CHECK_CAPS_FLUSH) ? " FLUSH" : "",
          (flags & CHECK_CAPS_NOINVAL) ? " NOINVAL" : "");
 
     /*
      * If we no longer need to hold onto old our caps, and we may
      * have cached pages, but don't want them, then try to invalidate.
      * If we fail, it's because pages are locked.... try again later.
      */
     if ((!(flags & CHECK_CAPS_NOINVAL) || mdsc->stopping) &&
         S_ISREG(inode->i_mode) &&
         !(ci->i_wb_ref || ci->i_wrbuffer_ref) &&   /* no dirty pages... */
         inode->i_data.nrpages &&        /* have cached pages */
         (revoking & (CEPH_CAP_FILE_CACHE|
              CEPH_CAP_FILE_LAZYIO)) && /*  or revoking cache */
         !tried_invalidate) {
         dout("check_caps trying to invalidate on %llx.%llx\n",
              ceph_vinop(inode));
         if (try_nonblocking_invalidate(inode) < 0) {
             dout("check_caps queuing invalidate\n");
             queue_invalidate = true;
             ci->i_rdcache_revoking = ci->i_rdcache_gen;
         }
         tried_invalidate = true;
         goto retry;
     }
 
     for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
         int mflags = 0;
         struct cap_msg_args arg;
 
         cap = rb_entry(p, struct ceph_cap, ci_node);
 
         /* avoid looping forever */
         if (mds >= cap->mds ||
             ((flags & CHECK_CAPS_AUTHONLY) && cap != ci->i_auth_cap))
             continue;
 
         /*
          * If we have an auth cap, we don't need to consider any
          * overlapping caps as used.
          */
         cap_used = used;
         if (ci->i_auth_cap && cap != ci->i_auth_cap)
             cap_used &= ~ci->i_auth_cap->issued;
 
         revoking = cap->implemented & ~cap->issued;
         dout(" mds%d cap %p used %s issued %s implemented %s revoking %s\n",
              cap->mds, cap, ceph_cap_string(cap_used),
              ceph_cap_string(cap->issued),
              ceph_cap_string(cap->implemented),
              ceph_cap_string(revoking));
 
         if (cap == ci->i_auth_cap &&
             (cap->issued & CEPH_CAP_FILE_WR)) {
             /* request larger max_size from MDS? */
             if (ci->i_wanted_max_size > ci->i_max_size &&
                 ci->i_wanted_max_size > ci->i_requested_max_size) {
                 dout("requesting new max_size\n");
                 goto ack;
             }
 
             /* approaching file_max? */
             if (__ceph_should_report_size(ci)) {
                 dout("i_size approaching max_size\n");
                 goto ack;
             }
         }
         /* flush anything dirty? */
         if (cap == ci->i_auth_cap) {
             if ((flags & CHECK_CAPS_FLUSH) && ci->i_dirty_caps) {
                 dout("flushing dirty caps\n");
                 goto ack;
             }
             if (ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS) {
                 dout("flushing snap caps\n");
                 goto ack;
             }
         }
 
         /* completed revocation? going down and there are no caps? */
         if (revoking) {
             if ((revoking & cap_used) == 0) {
                 dout("completed revocation of %s\n",
                       ceph_cap_string(cap->implemented & ~cap->issued));
                 goto ack;
             }
 
             /*
              * If the "i_wrbuffer_ref" was increased by mmap or generic
              * cache write just before the ceph_check_caps() is called,
              * the Fb capability revoking will fail this time. Then we
              * must wait for the BDI's delayed work to flush the dirty
              * pages and to release the "i_wrbuffer_ref", which will cost
              * at most 5 seconds. That means the MDS needs to wait at
              * most 5 seconds to finished the Fb capability's revocation.
              *
              * Let's queue a writeback for it.
              */
             if (S_ISREG(inode->i_mode) && ci->i_wrbuffer_ref &&
                 (revoking & CEPH_CAP_FILE_BUFFER))
                 queue_writeback = true;
         }
 
         /* want more caps from mds? */
         if (want & ~cap->mds_wanted) {
             if (want & ~(cap->mds_wanted | cap->issued))
                 goto ack;
             if (!__cap_is_valid(cap))
                 goto ack;
         }
 
         /* things we might delay */
         if ((cap->issued & ~retain) == 0)
             continue;     /* nope, all good */
 
 ack:
         ceph_put_mds_session(session);
         session = ceph_get_mds_session(cap->session);
 
         /* kick flushing and flush snaps before sending normal
          * cap message */
         if (cap == ci->i_auth_cap &&
             (ci->i_ceph_flags &
              (CEPH_I_KICK_FLUSH | CEPH_I_FLUSH_SNAPS))) {
             if (ci->i_ceph_flags & CEPH_I_KICK_FLUSH)
                 __kick_flushing_caps(mdsc, session, ci, 0);
             if (ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)
                 __ceph_flush_snaps(ci, session);
 
             goto retry;
         }
 
         if (cap == ci->i_auth_cap && ci->i_dirty_caps) {
             flushing = ci->i_dirty_caps;
             flush_tid = __mark_caps_flushing(inode, session, false,
                              &oldest_flush_tid);
             if (flags & CHECK_CAPS_FLUSH &&
                 list_empty(&session->s_cap_dirty))
                 mflags |= CEPH_CLIENT_CAPS_SYNC;
         } else {
             flushing = 0;
             flush_tid = 0;
             spin_lock(&mdsc->cap_dirty_lock);
             oldest_flush_tid = __get_oldest_flush_tid(mdsc);
             spin_unlock(&mdsc->cap_dirty_lock);
         }
 
         mds = cap->mds;  /* remember mds, so we don't repeat */
 
         __prep_cap(&arg, cap, CEPH_CAP_OP_UPDATE, mflags, cap_used,
                want, retain, flushing, flush_tid, oldest_flush_tid);
 
         spin_unlock(&ci->i_ceph_lock);
         __send_cap(&arg, ci);
         spin_lock(&ci->i_ceph_lock);
 
         goto retry; /* retake i_ceph_lock and restart our cap scan. */
     }
 
     /* periodically re-calculate caps wanted by open files */
     if (__ceph_is_any_real_caps(ci) &&
         list_empty(&ci->i_cap_delay_list) &&
         (file_wanted & ~CEPH_CAP_PIN) &&
         !(used & (CEPH_CAP_FILE_RD | CEPH_CAP_ANY_FILE_WR))) {
         __cap_delay_requeue(mdsc, ci);
     }
 
     spin_unlock(&ci->i_ceph_lock);
 
     ceph_put_mds_session(session);
     if (queue_writeback)
         ceph_queue_writeback(inode);
     if (queue_invalidate)
         ceph_queue_invalidate(inode);
 }
 
 /*
  * Try to flush dirty caps back to the auth mds.
  */
 static int try_flush_caps(struct inode *inode, u64 *ptid)
 {
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     struct ceph_inode_info *ci = ceph_inode(inode);
     int flushing = 0;
     u64 flush_tid = 0, oldest_flush_tid = 0;
 
     spin_lock(&ci->i_ceph_lock);
 retry_locked:
     if (ci->i_dirty_caps && ci->i_auth_cap) {
         struct ceph_cap *cap = ci->i_auth_cap;
         struct cap_msg_args arg;
         struct ceph_mds_session *session = cap->session;
 
         if (session->s_state < CEPH_MDS_SESSION_OPEN) {
             spin_unlock(&ci->i_ceph_lock);
             goto out;
         }
 
         if (ci->i_ceph_flags &
             (CEPH_I_KICK_FLUSH | CEPH_I_FLUSH_SNAPS)) {
             if (ci->i_ceph_flags & CEPH_I_KICK_FLUSH)
                 __kick_flushing_caps(mdsc, session, ci, 0);
             if (ci->i_ceph_flags & CEPH_I_FLUSH_SNAPS)
                 __ceph_flush_snaps(ci, session);
             goto retry_locked;
         }
 
         flushing = ci->i_dirty_caps;
         flush_tid = __mark_caps_flushing(inode, session, true,
                          &oldest_flush_tid);
 
         __prep_cap(&arg, cap, CEPH_CAP_OP_FLUSH, CEPH_CLIENT_CAPS_SYNC,
                __ceph_caps_used(ci), __ceph_caps_wanted(ci),
                (cap->issued | cap->implemented),
                flushing, flush_tid, oldest_flush_tid);
         spin_unlock(&ci->i_ceph_lock);
 
         __send_cap(&arg, ci);
     } else {
         if (!list_empty(&ci->i_cap_flush_list)) {
             struct ceph_cap_flush *cf =
                 list_last_entry(&ci->i_cap_flush_list,
                         struct ceph_cap_flush, i_list);
             cf->wake = true;
             flush_tid = cf->tid;
         }
         flushing = ci->i_flushing_caps;
         spin_unlock(&ci->i_ceph_lock);
     }
 out:
     *ptid = flush_tid;
     return flushing;
 }
 
 /*
  * Return true if we've flushed caps through the given flush_tid.
  */
 static int caps_are_flushed(struct inode *inode, u64 flush_tid)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int ret = 1;
 
     spin_lock(&ci->i_ceph_lock);
     if (!list_empty(&ci->i_cap_flush_list)) {
         struct ceph_cap_flush * cf =
             list_first_entry(&ci->i_cap_flush_list,
                      struct ceph_cap_flush, i_list);
         if (cf->tid <= flush_tid)
             ret = 0;
     }
     spin_unlock(&ci->i_ceph_lock);
     return ret;
 }
 
 /*
  * flush the mdlog and wait for any unsafe requests to complete.
  */
 static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
 {
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_mds_request *req1 = NULL, *req2 = NULL;
     unsigned int max_sessions;
     int ret, err = 0;
 
     spin_lock(&ci->i_unsafe_lock);
     if (S_ISDIR(inode->i_mode) && !list_empty(&ci->i_unsafe_dirops)) {
         req1 = list_last_entry(&ci->i_unsafe_dirops,
                     struct ceph_mds_request,
                     r_unsafe_dir_item);
         ceph_mdsc_get_request(req1);
     }
     if (!list_empty(&ci->i_unsafe_iops)) {
         req2 = list_last_entry(&ci->i_unsafe_iops,
                     struct ceph_mds_request,
                     r_unsafe_target_item);
         ceph_mdsc_get_request(req2);
     }
     spin_unlock(&ci->i_unsafe_lock);
 
     /*
      * The mdsc->max_sessions is unlikely to be changed
      * mostly, here we will retry it by reallocating the
      * sessions array memory to get rid of the mdsc->mutex
      * lock.
      */
 retry:
     max_sessions = mdsc->max_sessions;
 
     /*
      * Trigger to flush the journal logs in all the relevant MDSes
      * manually, or in the worst case we must wait at most 5 seconds
      * to wait the journal logs to be flushed by the MDSes periodically.
      */
     if ((req1 || req2) && likely(max_sessions)) {
         struct ceph_mds_session **sessions = NULL;
         struct ceph_mds_session *s;
         struct ceph_mds_request *req;
         int i;
 
         sessions = kzalloc(max_sessions * sizeof(s), GFP_KERNEL);
         if (!sessions) {
             err = -ENOMEM;
             goto out;
         }
 
         spin_lock(&ci->i_unsafe_lock);
         if (req1) {
             list_for_each_entry(req, &ci->i_unsafe_dirops,
                         r_unsafe_dir_item) {
                 s = req->r_session;
                 if (!s)
                     continue;
                 if (unlikely(s->s_mds >= max_sessions)) {
                     spin_unlock(&ci->i_unsafe_lock);
                     for (i = 0; i < max_sessions; i++) {
                         s = sessions[i];
                         if (s)
                             ceph_put_mds_session(s);
                     }
                     kfree(sessions);
                     goto retry;
                 }
                 if (!sessions[s->s_mds]) {
                     s = ceph_get_mds_session(s);
                     sessions[s->s_mds] = s;
                 }
             }
         }
         if (req2) {
             list_for_each_entry(req, &ci->i_unsafe_iops,
                         r_unsafe_target_item) {
                 s = req->r_session;
                 if (!s)
                     continue;
                 if (unlikely(s->s_mds >= max_sessions)) {
                     spin_unlock(&ci->i_unsafe_lock);
                     for (i = 0; i < max_sessions; i++) {
                         s = sessions[i];
                         if (s)
                             ceph_put_mds_session(s);
                     }
                     kfree(sessions);
                     goto retry;
                 }
                 if (!sessions[s->s_mds]) {
                     s = ceph_get_mds_session(s);
                     sessions[s->s_mds] = s;
                 }
             }
         }
         spin_unlock(&ci->i_unsafe_lock);
 
         /* the auth MDS */
         spin_lock(&ci->i_ceph_lock);
         if (ci->i_auth_cap) {
               s = ci->i_auth_cap->session;
               if (!sessions[s->s_mds])
                   sessions[s->s_mds] = ceph_get_mds_session(s);
         }
         spin_unlock(&ci->i_ceph_lock);
 
         /* send flush mdlog request to MDSes */
         for (i = 0; i < max_sessions; i++) {
             s = sessions[i];
             if (s) {
                 send_flush_mdlog(s);
                 ceph_put_mds_session(s);
             }
         }
         kfree(sessions);
     }
 
     dout("%s %p wait on tid %llu %llu\n", __func__,
          inode, req1 ? req1->r_tid : 0ULL, req2 ? req2->r_tid : 0ULL);
     if (req1) {
         ret = !wait_for_completion_timeout(&req1->r_safe_completion,
                     ceph_timeout_jiffies(req1->r_timeout));
         if (ret)
             err = -EIO;
     }
     if (req2) {
         ret = !wait_for_completion_timeout(&req2->r_safe_completion,
                     ceph_timeout_jiffies(req2->r_timeout));
         if (ret)
             err = -EIO;
     }
 
 out:
     if (req1)
         ceph_mdsc_put_request(req1);
     if (req2)
         ceph_mdsc_put_request(req2);
     return err;
 }
 
 int ceph_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
     struct inode *inode = file->f_mapping->host;
     struct ceph_inode_info *ci = ceph_inode(inode);
     u64 flush_tid;
     int ret, err;
     int dirty;
 
     dout("fsync %p%s\n", inode, datasync ? " datasync" : "");
 
     ret = file_write_and_wait_range(file, start, end);
     if (datasync)
         goto out;
 
     ret = ceph_wait_on_async_create(inode);
     if (ret)
         goto out;
 
     dirty = try_flush_caps(inode, &flush_tid);
     dout("fsync dirty caps are %s\n", ceph_cap_string(dirty));
 
     err = flush_mdlog_and_wait_inode_unsafe_requests(inode);
 
     /*
      * only wait on non-file metadata writeback (the mds
      * can recover size and mtime, so we don't need to
      * wait for that)
      */
     if (!err && (dirty & ~CEPH_CAP_ANY_FILE_WR)) {
         err = wait_event_interruptible(ci->i_cap_wq,
                     caps_are_flushed(inode, flush_tid));
     }
 
     if (err < 0)
         ret = err;
 
     err = file_check_and_advance_wb_err(file);
     if (err < 0)
         ret = err;
 out:
     dout("fsync %p%s result=%d\n", inode, datasync ? " datasync" : "", ret);
     return ret;
 }
 
 /*
  * Flush any dirty caps back to the mds.  If we aren't asked to wait,
  * queue inode for flush but don't do so immediately, because we can
  * get by with fewer MDS messages if we wait for data writeback to
  * complete first.
  */
 int ceph_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     u64 flush_tid;
     int err = 0;
     int dirty;
     int wait = (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync);
 
     dout("write_inode %p wait=%d\n", inode, wait);
     ceph_fscache_unpin_writeback(inode, wbc);
     if (wait) {
         err = ceph_wait_on_async_create(inode);
         if (err)
             return err;
         dirty = try_flush_caps(inode, &flush_tid);
         if (dirty)
             err = wait_event_interruptible(ci->i_cap_wq,
                        caps_are_flushed(inode, flush_tid));
     } else {
         struct ceph_mds_client *mdsc =
             ceph_sb_to_client(inode->i_sb)->mdsc;
 
         spin_lock(&ci->i_ceph_lock);
         if (__ceph_caps_dirty(ci))
             __cap_delay_requeue_front(mdsc, ci);
         spin_unlock(&ci->i_ceph_lock);
     }
     return err;
 }
 
 static void __kick_flushing_caps(struct ceph_mds_client *mdsc,
                  struct ceph_mds_session *session,
                  struct ceph_inode_info *ci,
                  u64 oldest_flush_tid)
     __releases(ci->i_ceph_lock)
     __acquires(ci->i_ceph_lock)
 {
     struct inode *inode = &ci->netfs.inode;
     struct ceph_cap *cap;
     struct ceph_cap_flush *cf;
     int ret;
     u64 first_tid = 0;
     u64 last_snap_flush = 0;
 
     /* Don't do anything until create reply comes in */
     if (ci->i_ceph_flags & CEPH_I_ASYNC_CREATE)
         return;
 
     ci->i_ceph_flags &= ~CEPH_I_KICK_FLUSH;
 
     list_for_each_entry_reverse(cf, &ci->i_cap_flush_list, i_list) {
         if (cf->is_capsnap) {
             last_snap_flush = cf->tid;
             break;
         }
     }
 
     list_for_each_entry(cf, &ci->i_cap_flush_list, i_list) {
         if (cf->tid < first_tid)
             continue;
 
         cap = ci->i_auth_cap;
         if (!(cap && cap->session == session)) {
             pr_err("%p auth cap %p not mds%d ???\n",
                    inode, cap, session->s_mds);
             break;
         }
 
         first_tid = cf->tid + 1;
 
         if (!cf->is_capsnap) {
             struct cap_msg_args arg;
 
             dout("kick_flushing_caps %p cap %p tid %llu %s\n",
                  inode, cap, cf->tid, ceph_cap_string(cf->caps));
             __prep_cap(&arg, cap, CEPH_CAP_OP_FLUSH,
                      (cf->tid < last_snap_flush ?
                       CEPH_CLIENT_CAPS_PENDING_CAPSNAP : 0),
                       __ceph_caps_used(ci),
                       __ceph_caps_wanted(ci),
                       (cap->issued | cap->implemented),
                       cf->caps, cf->tid, oldest_flush_tid);
             spin_unlock(&ci->i_ceph_lock);
             __send_cap(&arg, ci);
         } else {
             struct ceph_cap_snap *capsnap =
                     container_of(cf, struct ceph_cap_snap,
                             cap_flush);
             dout("kick_flushing_caps %p capsnap %p tid %llu %s\n",
                  inode, capsnap, cf->tid,
                  ceph_cap_string(capsnap->dirty));
 
             refcount_inc(&capsnap->nref);
             spin_unlock(&ci->i_ceph_lock);
 
             ret = __send_flush_snap(inode, session, capsnap, cap->mseq,
                         oldest_flush_tid);
             if (ret < 0) {
                 pr_err("kick_flushing_caps: error sending "
                     "cap flushsnap, ino (%llx.%llx) "
                     "tid %llu follows %llu\n",
                     ceph_vinop(inode), cf->tid,
                     capsnap->follows);
             }
 
             ceph_put_cap_snap(capsnap);
         }
 
         spin_lock(&ci->i_ceph_lock);
     }
 }
 
 void ceph_early_kick_flushing_caps(struct ceph_mds_client *mdsc,
                    struct ceph_mds_session *session)
 {
     struct ceph_inode_info *ci;
     struct ceph_cap *cap;
     u64 oldest_flush_tid;
 
     dout("early_kick_flushing_caps mds%d\n", session->s_mds);
 
     spin_lock(&mdsc->cap_dirty_lock);
     oldest_flush_tid = __get_oldest_flush_tid(mdsc);
     spin_unlock(&mdsc->cap_dirty_lock);
 
     list_for_each_entry(ci, &session->s_cap_flushing, i_flushing_item) {
         spin_lock(&ci->i_ceph_lock);
         cap = ci->i_auth_cap;
         if (!(cap && cap->session == session)) {
             pr_err("%p auth cap %p not mds%d ???\n",
                 &ci->netfs.inode, cap, session->s_mds);
             spin_unlock(&ci->i_ceph_lock);
             continue;
         }
 
 
         /*
          * if flushing caps were revoked, we re-send the cap flush
          * in client reconnect stage. This guarantees MDS * processes
          * the cap flush message before issuing the flushing caps to
          * other client.
          */
         if ((cap->issued & ci->i_flushing_caps) !=
             ci->i_flushing_caps) {
             /* encode_caps_cb() also will reset these sequence
              * numbers. make sure sequence numbers in cap flush
              * message match later reconnect message */
             cap->seq = 0;
             cap->issue_seq = 0;
             cap->mseq = 0;
             __kick_flushing_caps(mdsc, session, ci,
                          oldest_flush_tid);
         } else {
             ci->i_ceph_flags |= CEPH_I_KICK_FLUSH;
         }
 
         spin_unlock(&ci->i_ceph_lock);
     }
 }
 
 void ceph_kick_flushing_caps(struct ceph_mds_client *mdsc,
                  struct ceph_mds_session *session)
 {
     struct ceph_inode_info *ci;
     struct ceph_cap *cap;
     u64 oldest_flush_tid;
 
     lockdep_assert_held(&session->s_mutex);
 
     dout("kick_flushing_caps mds%d\n", session->s_mds);
 
     spin_lock(&mdsc->cap_dirty_lock);
     oldest_flush_tid = __get_oldest_flush_tid(mdsc);
     spin_unlock(&mdsc->cap_dirty_lock);
 
     list_for_each_entry(ci, &session->s_cap_flushing, i_flushing_item) {
         spin_lock(&ci->i_ceph_lock);
         cap = ci->i_auth_cap;
         if (!(cap && cap->session == session)) {
             pr_err("%p auth cap %p not mds%d ???\n",
                 &ci->netfs.inode, cap, session->s_mds);
             spin_unlock(&ci->i_ceph_lock);
             continue;
         }
         if (ci->i_ceph_flags & CEPH_I_KICK_FLUSH) {
             __kick_flushing_caps(mdsc, session, ci,
                          oldest_flush_tid);
         }
         spin_unlock(&ci->i_ceph_lock);
     }
 }
 
 void ceph_kick_flushing_inode_caps(struct ceph_mds_session *session,
                    struct ceph_inode_info *ci)
 {
     struct ceph_mds_client *mdsc = session->s_mdsc;
     struct ceph_cap *cap = ci->i_auth_cap;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("%s %p flushing %s\n", __func__, &ci->netfs.inode,
          ceph_cap_string(ci->i_flushing_caps));
 
     if (!list_empty(&ci->i_cap_flush_list)) {
         u64 oldest_flush_tid;
         spin_lock(&mdsc->cap_dirty_lock);
         list_move_tail(&ci->i_flushing_item,
                    &cap->session->s_cap_flushing);
         oldest_flush_tid = __get_oldest_flush_tid(mdsc);
         spin_unlock(&mdsc->cap_dirty_lock);
 
         __kick_flushing_caps(mdsc, session, ci, oldest_flush_tid);
     }
 }
 
 
 /*
  * Take references to capabilities we hold, so that we don't release
  * them to the MDS prematurely.
  */
 void ceph_take_cap_refs(struct ceph_inode_info *ci, int got,
                 bool snap_rwsem_locked)
 {
     lockdep_assert_held(&ci->i_ceph_lock);
 
     if (got & CEPH_CAP_PIN)
         ci->i_pin_ref++;
     if (got & CEPH_CAP_FILE_RD)
         ci->i_rd_ref++;
     if (got & CEPH_CAP_FILE_CACHE)
         ci->i_rdcache_ref++;
     if (got & CEPH_CAP_FILE_EXCL)
         ci->i_fx_ref++;
     if (got & CEPH_CAP_FILE_WR) {
         if (ci->i_wr_ref == 0 && !ci->i_head_snapc) {
             BUG_ON(!snap_rwsem_locked);
             ci->i_head_snapc = ceph_get_snap_context(
                     ci->i_snap_realm->cached_context);
         }
         ci->i_wr_ref++;
     }
     if (got & CEPH_CAP_FILE_BUFFER) {
         if (ci->i_wb_ref == 0)
             ihold(&ci->netfs.inode);
         ci->i_wb_ref++;
         dout("%s %p wb %d -> %d (?)\n", __func__,
              &ci->netfs.inode, ci->i_wb_ref-1, ci->i_wb_ref);
     }
 }
 
 /*
  * Try to grab cap references.  Specify those refs we @want, and the
  * minimal set we @need.  Also include the larger offset we are writing
  * to (when applicable), and check against max_size here as well.
  * Note that caller is responsible for ensuring max_size increases are
  * requested from the MDS.
  *
  * Returns 0 if caps were not able to be acquired (yet), 1 if succeed,
  * or a negative error code. There are 3 speical error codes:
  *  -EAGAIN:  need to sleep but non-blocking is specified
  *  -EFBIG:   ask caller to call check_max_size() and try again.
  *  -EUCLEAN: ask caller to call ceph_renew_caps() and try again.
  */
 enum {
     /* first 8 bits are reserved for CEPH_FILE_MODE_FOO */
     NON_BLOCKING    = (1 << 8),
     CHECK_FILELOCK  = (1 << 9),
 };
 
 static int try_get_cap_refs(struct inode *inode, int need, int want,
                 loff_t endoff, int flags, int *got)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
     int ret = 0;
     int have, implemented;
     bool snap_rwsem_locked = false;
 
     dout("get_cap_refs %p need %s want %s\n", inode,
          ceph_cap_string(need), ceph_cap_string(want));
 
 again:
     spin_lock(&ci->i_ceph_lock);
 
     if ((flags & CHECK_FILELOCK) &&
         (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK)) {
         dout("try_get_cap_refs %p error filelock\n", inode);
         ret = -EIO;
         goto out_unlock;
     }
 
     /* finish pending truncate */
     while (ci->i_truncate_pending) {
         spin_unlock(&ci->i_ceph_lock);
         if (snap_rwsem_locked) {
             up_read(&mdsc->snap_rwsem);
             snap_rwsem_locked = false;
         }
         __ceph_do_pending_vmtruncate(inode);
         spin_lock(&ci->i_ceph_lock);
     }
 
     have = __ceph_caps_issued(ci, &implemented);
 
     if (have & need & CEPH_CAP_FILE_WR) {
         if (endoff >= 0 && endoff > (loff_t)ci->i_max_size) {
             dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
                  inode, endoff, ci->i_max_size);
             if (endoff > ci->i_requested_max_size)
                 ret = ci->i_auth_cap ? -EFBIG : -EUCLEAN;
             goto out_unlock;
         }
         /*
          * If a sync write is in progress, we must wait, so that we
          * can get a final snapshot value for size+mtime.
          */
         if (__ceph_have_pending_cap_snap(ci)) {
             dout("get_cap_refs %p cap_snap_pending\n", inode);
             goto out_unlock;
         }
     }
 
     if ((have & need) == need) {
         /*
          * Look at (implemented & ~have & not) so that we keep waiting
          * on transition from wanted -> needed caps.  This is needed
          * for WRBUFFER|WR -> WR to avoid a new WR sync write from
          * going before a prior buffered writeback happens.
          */
         int not = want & ~(have & need);
         int revoking = implemented & ~have;
         dout("get_cap_refs %p have %s but not %s (revoking %s)\n",
              inode, ceph_cap_string(have), ceph_cap_string(not),
              ceph_cap_string(revoking));
         if ((revoking & not) == 0) {
             if (!snap_rwsem_locked &&
                 !ci->i_head_snapc &&
                 (need & CEPH_CAP_FILE_WR)) {
                 if (!down_read_trylock(&mdsc->snap_rwsem)) {
                     /*
                      * we can not call down_read() when
                      * task isn't in TASK_RUNNING state
                      */
                     if (flags & NON_BLOCKING) {
                         ret = -EAGAIN;
                         goto out_unlock;
                     }
 
                     spin_unlock(&ci->i_ceph_lock);
                     down_read(&mdsc->snap_rwsem);
                     snap_rwsem_locked = true;
                     goto again;
                 }
                 snap_rwsem_locked = true;
             }
             if ((have & want) == want)
                 *got = need | want;
             else
                 *got = need;
             ceph_take_cap_refs(ci, *got, true);
             ret = 1;
         }
     } else {
         int session_readonly = false;
         int mds_wanted;
         if (ci->i_auth_cap &&
             (need & (CEPH_CAP_FILE_WR | CEPH_CAP_FILE_EXCL))) {
             struct ceph_mds_session *s = ci->i_auth_cap->session;
             spin_lock(&s->s_cap_lock);
             session_readonly = s->s_readonly;
             spin_unlock(&s->s_cap_lock);
         }
         if (session_readonly) {
             dout("get_cap_refs %p need %s but mds%d readonly\n",
                  inode, ceph_cap_string(need), ci->i_auth_cap->mds);
             ret = -EROFS;
             goto out_unlock;
         }
 
         if (ceph_inode_is_shutdown(inode)) {
             dout("get_cap_refs %p inode is shutdown\n", inode);
             ret = -ESTALE;
             goto out_unlock;
         }
         mds_wanted = __ceph_caps_mds_wanted(ci, false);
         if (need & ~mds_wanted) {
             dout("get_cap_refs %p need %s > mds_wanted %s\n",
                  inode, ceph_cap_string(need),
                  ceph_cap_string(mds_wanted));
             ret = -EUCLEAN;
             goto out_unlock;
         }
 
         dout("get_cap_refs %p have %s need %s\n", inode,
              ceph_cap_string(have), ceph_cap_string(need));
     }
 out_unlock:
 
     __ceph_touch_fmode(ci, mdsc, flags);
 
     spin_unlock(&ci->i_ceph_lock);
     if (snap_rwsem_locked)
         up_read(&mdsc->snap_rwsem);
 
     if (!ret)
         ceph_update_cap_mis(&mdsc->metric);
     else if (ret == 1)
         ceph_update_cap_hit(&mdsc->metric);
 
     dout("get_cap_refs %p ret %d got %s\n", inode,
          ret, ceph_cap_string(*got));
     return ret;
 }
 
 /*
  * Check the offset we are writing up to against our current
  * max_size.  If necessary, tell the MDS we want to write to
  * a larger offset.
  */
 static void check_max_size(struct inode *inode, loff_t endoff)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int check = 0;
 
     /* do we need to explicitly request a larger max_size? */
     spin_lock(&ci->i_ceph_lock);
     if (endoff >= ci->i_max_size && endoff > ci->i_wanted_max_size) {
         dout("write %p at large endoff %llu, req max_size\n",
              inode, endoff);
         ci->i_wanted_max_size = endoff;
     }
     /* duplicate ceph_check_caps()'s logic */
     if (ci->i_auth_cap &&
         (ci->i_auth_cap->issued & CEPH_CAP_FILE_WR) &&
         ci->i_wanted_max_size > ci->i_max_size &&
         ci->i_wanted_max_size > ci->i_requested_max_size)
         check = 1;
     spin_unlock(&ci->i_ceph_lock);
     if (check)
         ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
 }
 
 static inline int get_used_fmode(int caps)
 {
     int fmode = 0;
     if (caps & CEPH_CAP_FILE_RD)
         fmode |= CEPH_FILE_MODE_RD;
     if (caps & CEPH_CAP_FILE_WR)
         fmode |= CEPH_FILE_MODE_WR;
     return fmode;
 }
 
 int ceph_try_get_caps(struct inode *inode, int need, int want,
               bool nonblock, int *got)
 {
     int ret, flags;
 
     BUG_ON(need & ~CEPH_CAP_FILE_RD);
     BUG_ON(want & ~(CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO |
             CEPH_CAP_FILE_SHARED | CEPH_CAP_FILE_EXCL |
             CEPH_CAP_ANY_DIR_OPS));
     if (need) {
         ret = ceph_pool_perm_check(inode, need);
         if (ret < 0)
             return ret;
     }
 
     flags = get_used_fmode(need | want);
     if (nonblock)
         flags |= NON_BLOCKING;
 
     ret = try_get_cap_refs(inode, need, want, 0, flags, got);
     /* three special error codes */
     if (ret == -EAGAIN || ret == -EFBIG || ret == -EUCLEAN)
         ret = 0;
     return ret;
 }
 
 /*
  * Wait for caps, and take cap references.  If we can't get a WR cap
  * due to a small max_size, make sure we check_max_size (and possibly
  * ask the mds) so we don't get hung up indefinitely.
  */
 int ceph_get_caps(struct file *filp, int need, int want, loff_t endoff, int *got)
 {
     struct ceph_file_info *fi = filp->private_data;
     struct inode *inode = file_inode(filp);
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
     int ret, _got, flags;
 
     ret = ceph_pool_perm_check(inode, need);
     if (ret < 0)
         return ret;
 
     if ((fi->fmode & CEPH_FILE_MODE_WR) &&
         fi->filp_gen != READ_ONCE(fsc->filp_gen))
         return -EBADF;
 
     flags = get_used_fmode(need | want);
 
     while (true) {
         flags &= CEPH_FILE_MODE_MASK;
         if (atomic_read(&fi->num_locks))
             flags |= CHECK_FILELOCK;
         _got = 0;
         ret = try_get_cap_refs(inode, need, want, endoff,
                        flags, &_got);
         WARN_ON_ONCE(ret == -EAGAIN);
         if (!ret) {
             struct ceph_mds_client *mdsc = fsc->mdsc;
             struct cap_wait cw;
             DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
             cw.ino = ceph_ino(inode);
             cw.tgid = current->tgid;
             cw.need = need;
             cw.want = want;
 
             spin_lock(&mdsc->caps_list_lock);
             list_add(&cw.list, &mdsc->cap_wait_list);
             spin_unlock(&mdsc->caps_list_lock);
 
             /* make sure used fmode not timeout */
             ceph_get_fmode(ci, flags, FMODE_WAIT_BIAS);
             add_wait_queue(&ci->i_cap_wq, &wait);
 
             flags |= NON_BLOCKING;
             while (!(ret = try_get_cap_refs(inode, need, want,
                             endoff, flags, &_got))) {
                 if (signal_pending(current)) {
                     ret = -ERESTARTSYS;
                     break;
                 }
                 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
             }
 
             remove_wait_queue(&ci->i_cap_wq, &wait);
             ceph_put_fmode(ci, flags, FMODE_WAIT_BIAS);
 
             spin_lock(&mdsc->caps_list_lock);
             list_del(&cw.list);
             spin_unlock(&mdsc->caps_list_lock);
 
             if (ret == -EAGAIN)
                 continue;
         }
 
         if ((fi->fmode & CEPH_FILE_MODE_WR) &&
             fi->filp_gen != READ_ONCE(fsc->filp_gen)) {
             if (ret >= 0 && _got)
                 ceph_put_cap_refs(ci, _got);
             return -EBADF;
         }
 
         if (ret < 0) {
             if (ret == -EFBIG || ret == -EUCLEAN) {
                 int ret2 = ceph_wait_on_async_create(inode);
                 if (ret2 < 0)
                     return ret2;
             }
             if (ret == -EFBIG) {
                 check_max_size(inode, endoff);
                 continue;
             }
             if (ret == -EUCLEAN) {
                 /* session was killed, try renew caps */
                 ret = ceph_renew_caps(inode, flags);
                 if (ret == 0)
                     continue;
             }
             return ret;
         }
 
         if (S_ISREG(ci->netfs.inode.i_mode) &&
             ceph_has_inline_data(ci) &&
             (_got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) &&
             i_size_read(inode) > 0) {
             struct page *page =
                 find_get_page(inode->i_mapping, 0);
             if (page) {
                 bool uptodate = PageUptodate(page);
 
                 put_page(page);
                 if (uptodate)
                     break;
             }
             /*
              * drop cap refs first because getattr while
              * holding * caps refs can cause deadlock.
              */
             ceph_put_cap_refs(ci, _got);
             _got = 0;
 
             /*
              * getattr request will bring inline data into
              * page cache
              */
             ret = __ceph_do_getattr(inode, NULL,
                         CEPH_STAT_CAP_INLINE_DATA,
                         true);
             if (ret < 0)
                 return ret;
             continue;
         }
         break;
     }
     *got = _got;
     return 0;
 }
 
 /*
  * Take cap refs.  Caller must already know we hold at least one ref
  * on the caps in question or we don't know this is safe.
  */
 void ceph_get_cap_refs(struct ceph_inode_info *ci, int caps)
 {
     spin_lock(&ci->i_ceph_lock);
     ceph_take_cap_refs(ci, caps, false);
     spin_unlock(&ci->i_ceph_lock);
 }
 
 
 /*
  * drop cap_snap that is not associated with any snapshot.
  * we don't need to send FLUSHSNAP message for it.
  */
 static int ceph_try_drop_cap_snap(struct ceph_inode_info *ci,
                   struct ceph_cap_snap *capsnap)
 {
     if (!capsnap->need_flush &&
         !capsnap->writing && !capsnap->dirty_pages) {
         dout("dropping cap_snap %p follows %llu\n",
              capsnap, capsnap->follows);
         BUG_ON(capsnap->cap_flush.tid > 0);
         ceph_put_snap_context(capsnap->context);
         if (!list_is_last(&capsnap->ci_item, &ci->i_cap_snaps))
             ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
 
         list_del(&capsnap->ci_item);
         ceph_put_cap_snap(capsnap);
         return 1;
     }
     return 0;
 }
 
 enum put_cap_refs_mode {
     PUT_CAP_REFS_SYNC = 0,
     PUT_CAP_REFS_NO_CHECK,
     PUT_CAP_REFS_ASYNC,
 };
 
 /*
  * Release cap refs.
  *
  * If we released the last ref on any given cap, call ceph_check_caps
  * to release (or schedule a release).
  *
  * If we are releasing a WR cap (from a sync write), finalize any affected
  * cap_snap, and wake up any waiters.
  */
 static void __ceph_put_cap_refs(struct ceph_inode_info *ci, int had,
                 enum put_cap_refs_mode mode)
 {
     struct inode *inode = &ci->netfs.inode;
     int last = 0, put = 0, flushsnaps = 0, wake = 0;
     bool check_flushsnaps = false;
 
     spin_lock(&ci->i_ceph_lock);
     if (had & CEPH_CAP_PIN)
         --ci->i_pin_ref;
     if (had & CEPH_CAP_FILE_RD)
         if (--ci->i_rd_ref == 0)
             last++;
     if (had & CEPH_CAP_FILE_CACHE)
         if (--ci->i_rdcache_ref == 0)
             last++;
     if (had & CEPH_CAP_FILE_EXCL)
         if (--ci->i_fx_ref == 0)
             last++;
     if (had & CEPH_CAP_FILE_BUFFER) {
         if (--ci->i_wb_ref == 0) {
             last++;
             /* put the ref held by ceph_take_cap_refs() */
             put++;
             check_flushsnaps = true;
         }
         dout("put_cap_refs %p wb %d -> %d (?)\n",
              inode, ci->i_wb_ref+1, ci->i_wb_ref);
     }
     if (had & CEPH_CAP_FILE_WR) {
         if (--ci->i_wr_ref == 0) {
             last++;
             check_flushsnaps = true;
             if (ci->i_wrbuffer_ref_head == 0 &&
                 ci->i_dirty_caps == 0 &&
                 ci->i_flushing_caps == 0) {
                 BUG_ON(!ci->i_head_snapc);
                 ceph_put_snap_context(ci->i_head_snapc);
                 ci->i_head_snapc = NULL;
             }
             /* see comment in __ceph_remove_cap() */
             if (!__ceph_is_any_real_caps(ci) && ci->i_snap_realm)
                 ceph_change_snap_realm(inode, NULL);
         }
     }
     if (check_flushsnaps && __ceph_have_pending_cap_snap(ci)) {
         struct ceph_cap_snap *capsnap =
             list_last_entry(&ci->i_cap_snaps,
                     struct ceph_cap_snap,
                     ci_item);
 
         capsnap->writing = 0;
         if (ceph_try_drop_cap_snap(ci, capsnap))
             /* put the ref held by ceph_queue_cap_snap() */
             put++;
         else if (__ceph_finish_cap_snap(ci, capsnap))
             flushsnaps = 1;
         wake = 1;
     }
     spin_unlock(&ci->i_ceph_lock);
 
     dout("put_cap_refs %p had %s%s%s\n", inode, ceph_cap_string(had),
          last ? " last" : "", put ? " put" : "");
 
     switch (mode) {
     case PUT_CAP_REFS_SYNC:
         if (last)
             ceph_check_caps(ci, 0, NULL);
         else if (flushsnaps)
             ceph_flush_snaps(ci, NULL);
         break;
     case PUT_CAP_REFS_ASYNC:
         if (last)
             ceph_queue_check_caps(inode);
         else if (flushsnaps)
             ceph_queue_flush_snaps(inode);
         break;
     default:
         break;
     }
     if (wake)
         wake_up_all(&ci->i_cap_wq);
     while (put-- > 0)
         iput(inode);
 }
 
 void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
 {
     __ceph_put_cap_refs(ci, had, PUT_CAP_REFS_SYNC);
 }
 
 void ceph_put_cap_refs_async(struct ceph_inode_info *ci, int had)
 {
     __ceph_put_cap_refs(ci, had, PUT_CAP_REFS_ASYNC);
 }
 
 void ceph_put_cap_refs_no_check_caps(struct ceph_inode_info *ci, int had)
 {
     __ceph_put_cap_refs(ci, had, PUT_CAP_REFS_NO_CHECK);
 }
 
 /*
  * Release @nr WRBUFFER refs on dirty pages for the given @snapc snap
  * context.  Adjust per-snap dirty page accounting as appropriate.
  * Once all dirty data for a cap_snap is flushed, flush snapped file
  * metadata back to the MDS.  If we dropped the last ref, call
  * ceph_check_caps.
  */
 void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
                 struct ceph_snap_context *snapc)
 {
     struct inode *inode = &ci->netfs.inode;
     struct ceph_cap_snap *capsnap = NULL, *iter;
     int put = 0;
     bool last = false;
     bool flush_snaps = false;
     bool complete_capsnap = false;
 
     spin_lock(&ci->i_ceph_lock);
     ci->i_wrbuffer_ref -= nr;
     if (ci->i_wrbuffer_ref == 0) {
         last = true;
         put++;
     }
 
     if (ci->i_head_snapc == snapc) {
         ci->i_wrbuffer_ref_head -= nr;
         if (ci->i_wrbuffer_ref_head == 0 &&
             ci->i_wr_ref == 0 &&
             ci->i_dirty_caps == 0 &&
             ci->i_flushing_caps == 0) {
             BUG_ON(!ci->i_head_snapc);
             ceph_put_snap_context(ci->i_head_snapc);
             ci->i_head_snapc = NULL;
         }
         dout("put_wrbuffer_cap_refs on %p head %d/%d -> %d/%d %s\n",
              inode,
              ci->i_wrbuffer_ref+nr, ci->i_wrbuffer_ref_head+nr,
              ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
              last ? " LAST" : "");
     } else {
         list_for_each_entry(iter, &ci->i_cap_snaps, ci_item) {
             if (iter->context == snapc) {
                 capsnap = iter;
                 break;
             }
         }
 
         if (!capsnap) {
             /*
              * The capsnap should already be removed when removing
              * auth cap in the case of a forced unmount.
              */
             WARN_ON_ONCE(ci->i_auth_cap);
             goto unlock;
         }
 
         capsnap->dirty_pages -= nr;
         if (capsnap->dirty_pages == 0) {
             complete_capsnap = true;
             if (!capsnap->writing) {
                 if (ceph_try_drop_cap_snap(ci, capsnap)) {
                     put++;
                 } else {
                     ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
                     flush_snaps = true;
                 }
             }
         }
         dout("put_wrbuffer_cap_refs on %p cap_snap %p "
              " snap %lld %d/%d -> %d/%d %s%s\n",
              inode, capsnap, capsnap->context->seq,
              ci->i_wrbuffer_ref+nr, capsnap->dirty_pages + nr,
              ci->i_wrbuffer_ref, capsnap->dirty_pages,
              last ? " (wrbuffer last)" : "",
              complete_capsnap ? " (complete capsnap)" : "");
     }
 
 unlock:
     spin_unlock(&ci->i_ceph_lock);
 
     if (last) {
         ceph_check_caps(ci, 0, NULL);
     } else if (flush_snaps) {
         ceph_flush_snaps(ci, NULL);
     }
     if (complete_capsnap)
         wake_up_all(&ci->i_cap_wq);
     while (put-- > 0) {
         iput(inode);
     }
 }
 
 /*
  * Invalidate unlinked inode's aliases, so we can drop the inode ASAP.
  */
 static void invalidate_aliases(struct inode *inode)
 {
     struct dentry *dn, *prev = NULL;
 
     dout("invalidate_aliases inode %p\n", inode);
     d_prune_aliases(inode);
     /*
      * For non-directory inode, d_find_alias() only returns
      * hashed dentry. After calling d_invalidate(), the
      * dentry becomes unhashed.
      *
      * For directory inode, d_find_alias() can return
      * unhashed dentry. But directory inode should have
      * one alias at most.
      */
     while ((dn = d_find_alias(inode))) {
         if (dn == prev) {
             dput(dn);
             break;
         }
         d_invalidate(dn);
         if (prev)
             dput(prev);
         prev = dn;
     }
     if (prev)
         dput(prev);
 }
 
 struct cap_extra_info {
     struct ceph_string *pool_ns;
     /* inline data */
     u64 inline_version;
     void *inline_data;
     u32 inline_len;
     /* dirstat */
     bool dirstat_valid;
     u64 nfiles;
     u64 nsubdirs;
     u64 change_attr;
     /* currently issued */
     int issued;
     struct timespec64 btime;
 };
 
 /*
  * Handle a cap GRANT message from the MDS.  (Note that a GRANT may
  * actually be a revocation if it specifies a smaller cap set.)
  *
  * caller holds s_mutex and i_ceph_lock, we drop both.
  */
 static void handle_cap_grant(struct inode *inode,
                  struct ceph_mds_session *session,
                  struct ceph_cap *cap,
                  struct ceph_mds_caps *grant,
                  struct ceph_buffer *xattr_buf,
                  struct cap_extra_info *extra_info)
     __releases(ci->i_ceph_lock)
     __releases(session->s_mdsc->snap_rwsem)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int seq = le32_to_cpu(grant->seq);
     int newcaps = le32_to_cpu(grant->caps);
     int used, wanted, dirty;
     u64 size = le64_to_cpu(grant->size);
     u64 max_size = le64_to_cpu(grant->max_size);
     unsigned char check_caps = 0;
     bool was_stale = cap->cap_gen < atomic_read(&session->s_cap_gen);
     bool wake = false;
     bool writeback = false;
     bool queue_trunc = false;
     bool queue_invalidate = false;
     bool deleted_inode = false;
     bool fill_inline = false;
 
     dout("handle_cap_grant inode %p cap %p mds%d seq %d %s\n",
          inode, cap, session->s_mds, seq, ceph_cap_string(newcaps));
     dout(" size %llu max_size %llu, i_size %llu\n", size, max_size,
         i_size_read(inode));
 
 
     /*
      * If CACHE is being revoked, and we have no dirty buffers,
      * try to invalidate (once).  (If there are dirty buffers, we
      * will invalidate _after_ writeback.)
      */
     if (S_ISREG(inode->i_mode) && /* don't invalidate readdir cache */
         ((cap->issued & ~newcaps) & CEPH_CAP_FILE_CACHE) &&
         (newcaps & CEPH_CAP_FILE_LAZYIO) == 0 &&
         !(ci->i_wrbuffer_ref || ci->i_wb_ref)) {
         if (try_nonblocking_invalidate(inode)) {
             /* there were locked pages.. invalidate later
                in a separate thread. */
             if (ci->i_rdcache_revoking != ci->i_rdcache_gen) {
                 queue_invalidate = true;
                 ci->i_rdcache_revoking = ci->i_rdcache_gen;
             }
         }
     }
 
     if (was_stale)
         cap->issued = cap->implemented = CEPH_CAP_PIN;
 
     /*
      * auth mds of the inode changed. we received the cap export message,
      * but still haven't received the cap import message. handle_cap_export
      * updated the new auth MDS' cap.
      *
      * "ceph_seq_cmp(seq, cap->seq) <= 0" means we are processing a message
      * that was sent before the cap import message. So don't remove caps.
      */
     if (ceph_seq_cmp(seq, cap->seq) <= 0) {
         WARN_ON(cap != ci->i_auth_cap);
         WARN_ON(cap->cap_id != le64_to_cpu(grant->cap_id));
         seq = cap->seq;
         newcaps |= cap->issued;
     }
 
     /* side effects now are allowed */
     cap->cap_gen = atomic_read(&session->s_cap_gen);
     cap->seq = seq;
 
     __check_cap_issue(ci, cap, newcaps);
 
     inode_set_max_iversion_raw(inode, extra_info->change_attr);
 
     if ((newcaps & CEPH_CAP_AUTH_SHARED) &&
         (extra_info->issued & CEPH_CAP_AUTH_EXCL) == 0) {
         umode_t mode = le32_to_cpu(grant->mode);
 
         if (inode_wrong_type(inode, mode))
             pr_warn_once("inode type changed! (ino %llx.%llx is 0%o, mds says 0%o)\n",
                      ceph_vinop(inode), inode->i_mode, mode);
         else
             inode->i_mode = mode;
         inode->i_uid = make_kuid(&init_user_ns, le32_to_cpu(grant->uid));
         inode->i_gid = make_kgid(&init_user_ns, le32_to_cpu(grant->gid));
         ci->i_btime = extra_info->btime;
         dout("%p mode 0%o uid.gid %d.%d\n", inode, inode->i_mode,
              from_kuid(&init_user_ns, inode->i_uid),
              from_kgid(&init_user_ns, inode->i_gid));
     }
 
     if ((newcaps & CEPH_CAP_LINK_SHARED) &&
         (extra_info->issued & CEPH_CAP_LINK_EXCL) == 0) {
         set_nlink(inode, le32_to_cpu(grant->nlink));
         if (inode->i_nlink == 0)
             deleted_inode = true;
     }
 
     if ((extra_info->issued & CEPH_CAP_XATTR_EXCL) == 0 &&
         grant->xattr_len) {
         int len = le32_to_cpu(grant->xattr_len);
         u64 version = le64_to_cpu(grant->xattr_version);
 
         if (version > ci->i_xattrs.version) {
             dout(" got new xattrs v%llu on %p len %d\n",
                  version, inode, len);
             if (ci->i_xattrs.blob)
                 ceph_buffer_put(ci->i_xattrs.blob);
             ci->i_xattrs.blob = ceph_buffer_get(xattr_buf);
             ci->i_xattrs.version = version;
             ceph_forget_all_cached_acls(inode);
             ceph_security_invalidate_secctx(inode);
         }
     }
 
     if (newcaps & CEPH_CAP_ANY_RD) {
         struct timespec64 mtime, atime, ctime;
         /* ctime/mtime/atime? */
         ceph_decode_timespec64(&mtime, &grant->mtime);
         ceph_decode_timespec64(&atime, &grant->atime);
         ceph_decode_timespec64(&ctime, &grant->ctime);
         ceph_fill_file_time(inode, extra_info->issued,
                     le32_to_cpu(grant->time_warp_seq),
                     &ctime, &mtime, &atime);
     }
 
     if ((newcaps & CEPH_CAP_FILE_SHARED) && extra_info->dirstat_valid) {
         ci->i_files = extra_info->nfiles;
         ci->i_subdirs = extra_info->nsubdirs;
     }
 
     if (newcaps & (CEPH_CAP_ANY_FILE_RD | CEPH_CAP_ANY_FILE_WR)) {
         /* file layout may have changed */
         s64 old_pool = ci->i_layout.pool_id;
         struct ceph_string *old_ns;
 
         ceph_file_layout_from_legacy(&ci->i_layout, &grant->layout);
         old_ns = rcu_dereference_protected(ci->i_layout.pool_ns,
                     lockdep_is_held(&ci->i_ceph_lock));
         rcu_assign_pointer(ci->i_layout.pool_ns, extra_info->pool_ns);
 
         if (ci->i_layout.pool_id != old_pool ||
             extra_info->pool_ns != old_ns)
             ci->i_ceph_flags &= ~CEPH_I_POOL_PERM;
 
         extra_info->pool_ns = old_ns;
 
         /* size/truncate_seq? */
         queue_trunc = ceph_fill_file_size(inode, extra_info->issued,
                     le32_to_cpu(grant->truncate_seq),
                     le64_to_cpu(grant->truncate_size),
                     size);
     }
 
     if (ci->i_auth_cap == cap && (newcaps & CEPH_CAP_ANY_FILE_WR)) {
         if (max_size != ci->i_max_size) {
             dout("max_size %lld -> %llu\n",
                  ci->i_max_size, max_size);
             ci->i_max_size = max_size;
             if (max_size >= ci->i_wanted_max_size) {
                 ci->i_wanted_max_size = 0;  /* reset */
                 ci->i_requested_max_size = 0;
             }
             wake = true;
         }
     }
 
     /* check cap bits */
     wanted = __ceph_caps_wanted(ci);
     used = __ceph_caps_used(ci);
     dirty = __ceph_caps_dirty(ci);
     dout(" my wanted = %s, used = %s, dirty %s\n",
          ceph_cap_string(wanted),
          ceph_cap_string(used),
          ceph_cap_string(dirty));
 
     if ((was_stale || le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) &&
         (wanted & ~(cap->mds_wanted | newcaps))) {
         /*
          * If mds is importing cap, prior cap messages that update
          * 'wanted' may get dropped by mds (migrate seq mismatch).
          *
          * We don't send cap message to update 'wanted' if what we
          * want are already issued. If mds revokes caps, cap message
          * that releases caps also tells mds what we want. But if
          * caps got revoked by mds forcedly (session stale). We may
          * haven't told mds what we want.
          */
         check_caps = 1;
     }
 
     /* revocation, grant, or no-op? */
     if (cap->issued & ~newcaps) {
         int revoking = cap->issued & ~newcaps;
 
         dout("revocation: %s -> %s (revoking %s)\n",
              ceph_cap_string(cap->issued),
              ceph_cap_string(newcaps),
              ceph_cap_string(revoking));
         if (S_ISREG(inode->i_mode) &&
             (revoking & used & CEPH_CAP_FILE_BUFFER))
             writeback = true;  /* initiate writeback; will delay ack */
         else if (queue_invalidate &&
              revoking == CEPH_CAP_FILE_CACHE &&
              (newcaps & CEPH_CAP_FILE_LAZYIO) == 0)
             ; /* do nothing yet, invalidation will be queued */
         else if (cap == ci->i_auth_cap)
             check_caps = 1; /* check auth cap only */
         else
             check_caps = 2; /* check all caps */
         cap->issued = newcaps;
         cap->implemented |= newcaps;
     } else if (cap->issued == newcaps) {
         dout("caps unchanged: %s -> %s\n",
              ceph_cap_string(cap->issued), ceph_cap_string(newcaps));
     } else {
         dout("grant: %s -> %s\n", ceph_cap_string(cap->issued),
              ceph_cap_string(newcaps));
         /* non-auth MDS is revoking the newly grant caps ? */
         if (cap == ci->i_auth_cap &&
             __ceph_caps_revoking_other(ci, cap, newcaps))
             check_caps = 2;
 
         cap->issued = newcaps;
         cap->implemented |= newcaps; /* add bits only, to
                           * avoid stepping on a
                           * pending revocation */
         wake = true;
     }
     BUG_ON(cap->issued & ~cap->implemented);
 
     if (extra_info->inline_version > 0 &&
         extra_info->inline_version >= ci->i_inline_version) {
         ci->i_inline_version = extra_info->inline_version;
         if (ci->i_inline_version != CEPH_INLINE_NONE &&
             (newcaps & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)))
             fill_inline = true;
     }
 
     if (le32_to_cpu(grant->op) == CEPH_CAP_OP_IMPORT) {
         if (ci->i_auth_cap == cap) {
             if (newcaps & ~extra_info->issued)
                 wake = true;
 
             if (ci->i_requested_max_size > max_size ||
                 !(le32_to_cpu(grant->wanted) & CEPH_CAP_ANY_FILE_WR)) {
                 /* re-request max_size if necessary */
                 ci->i_requested_max_size = 0;
                 wake = true;
             }
 
             ceph_kick_flushing_inode_caps(session, ci);
         }
         up_read(&session->s_mdsc->snap_rwsem);
     }
     spin_unlock(&ci->i_ceph_lock);
 
     if (fill_inline)
         ceph_fill_inline_data(inode, NULL, extra_info->inline_data,
                       extra_info->inline_len);
 
     if (queue_trunc)
         ceph_queue_vmtruncate(inode);
 
     if (writeback)
         /*
          * queue inode for writeback: we can't actually call
          * filemap_write_and_wait, etc. from message handler
          * context.
          */
         ceph_queue_writeback(inode);
     if (queue_invalidate)
         ceph_queue_invalidate(inode);
     if (deleted_inode)
         invalidate_aliases(inode);
     if (wake)
         wake_up_all(&ci->i_cap_wq);
 
     mutex_unlock(&session->s_mutex);
     if (check_caps == 1)
         ceph_check_caps(ci, CHECK_CAPS_AUTHONLY | CHECK_CAPS_NOINVAL,
                 session);
     else if (check_caps == 2)
         ceph_check_caps(ci, CHECK_CAPS_NOINVAL, session);
 }
 
 /*
  * Handle FLUSH_ACK from MDS, indicating that metadata we sent to the
  * MDS has been safely committed.
  */
 static void handle_cap_flush_ack(struct inode *inode, u64 flush_tid,
                  struct ceph_mds_caps *m,
                  struct ceph_mds_session *session,
                  struct ceph_cap *cap)
     __releases(ci->i_ceph_lock)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     struct ceph_cap_flush *cf, *tmp_cf;
     LIST_HEAD(to_remove);
     unsigned seq = le32_to_cpu(m->seq);
     int dirty = le32_to_cpu(m->dirty);
     int cleaned = 0;
     bool drop = false;
     bool wake_ci = false;
     bool wake_mdsc = false;
 
     list_for_each_entry_safe(cf, tmp_cf, &ci->i_cap_flush_list, i_list) {
         /* Is this the one that was flushed? */
         if (cf->tid == flush_tid)
             cleaned = cf->caps;
 
         /* Is this a capsnap? */
         if (cf->is_capsnap)
             continue;
 
         if (cf->tid <= flush_tid) {
             /*
              * An earlier or current tid. The FLUSH_ACK should
              * represent a superset of this flush's caps.
              */
             wake_ci |= __detach_cap_flush_from_ci(ci, cf);
             list_add_tail(&cf->i_list, &to_remove);
         } else {
             /*
              * This is a later one. Any caps in it are still dirty
              * so don't count them as cleaned.
              */
             cleaned &= ~cf->caps;
             if (!cleaned)
                 break;
         }
     }
 
     dout("handle_cap_flush_ack inode %p mds%d seq %d on %s cleaned %s,"
          " flushing %s -> %s\n",
          inode, session->s_mds, seq, ceph_cap_string(dirty),
          ceph_cap_string(cleaned), ceph_cap_string(ci->i_flushing_caps),
          ceph_cap_string(ci->i_flushing_caps & ~cleaned));
 
     if (list_empty(&to_remove) && !cleaned)
         goto out;
 
     ci->i_flushing_caps &= ~cleaned;
 
     spin_lock(&mdsc->cap_dirty_lock);
 
     list_for_each_entry(cf, &to_remove, i_list)
         wake_mdsc |= __detach_cap_flush_from_mdsc(mdsc, cf);
 
     if (ci->i_flushing_caps == 0) {
         if (list_empty(&ci->i_cap_flush_list)) {
             list_del_init(&ci->i_flushing_item);
             if (!list_empty(&session->s_cap_flushing)) {
                 dout(" mds%d still flushing cap on %p\n",
                      session->s_mds,
                      &list_first_entry(&session->s_cap_flushing,
                         struct ceph_inode_info,
                         i_flushing_item)->netfs.inode);
             }
         }
         mdsc->num_cap_flushing--;
         dout(" inode %p now !flushing\n", inode);
 
         if (ci->i_dirty_caps == 0) {
             dout(" inode %p now clean\n", inode);
             BUG_ON(!list_empty(&ci->i_dirty_item));
             drop = true;
             if (ci->i_wr_ref == 0 &&
                 ci->i_wrbuffer_ref_head == 0) {
                 BUG_ON(!ci->i_head_snapc);
                 ceph_put_snap_context(ci->i_head_snapc);
                 ci->i_head_snapc = NULL;
             }
         } else {
             BUG_ON(list_empty(&ci->i_dirty_item));
         }
     }
     spin_unlock(&mdsc->cap_dirty_lock);
 
 out:
     spin_unlock(&ci->i_ceph_lock);
 
     while (!list_empty(&to_remove)) {
         cf = list_first_entry(&to_remove,
                       struct ceph_cap_flush, i_list);
         list_del_init(&cf->i_list);
         if (!cf->is_capsnap)
             ceph_free_cap_flush(cf);
     }
 
     if (wake_ci)
         wake_up_all(&ci->i_cap_wq);
     if (wake_mdsc)
         wake_up_all(&mdsc->cap_flushing_wq);
     if (drop)
         iput(inode);
 }
 
 void __ceph_remove_capsnap(struct inode *inode, struct ceph_cap_snap *capsnap,
                bool *wake_ci, bool *wake_mdsc)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     bool ret;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("removing capsnap %p, inode %p ci %p\n", capsnap, inode, ci);
 
     list_del_init(&capsnap->ci_item);
     ret = __detach_cap_flush_from_ci(ci, &capsnap->cap_flush);
     if (wake_ci)
         *wake_ci = ret;
 
     spin_lock(&mdsc->cap_dirty_lock);
     if (list_empty(&ci->i_cap_flush_list))
         list_del_init(&ci->i_flushing_item);
 
     ret = __detach_cap_flush_from_mdsc(mdsc, &capsnap->cap_flush);
     if (wake_mdsc)
         *wake_mdsc = ret;
     spin_unlock(&mdsc->cap_dirty_lock);
 }
 
 void ceph_remove_capsnap(struct inode *inode, struct ceph_cap_snap *capsnap,
              bool *wake_ci, bool *wake_mdsc)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     WARN_ON_ONCE(capsnap->dirty_pages || capsnap->writing);
     __ceph_remove_capsnap(inode, capsnap, wake_ci, wake_mdsc);
 }
 
 /*
  * Handle FLUSHSNAP_ACK.  MDS has flushed snap data to disk and we can
  * throw away our cap_snap.
  *
  * Caller hold s_mutex.
  */
 static void handle_cap_flushsnap_ack(struct inode *inode, u64 flush_tid,
                      struct ceph_mds_caps *m,
                      struct ceph_mds_session *session)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
     u64 follows = le64_to_cpu(m->snap_follows);
     struct ceph_cap_snap *capsnap = NULL, *iter;
     bool wake_ci = false;
     bool wake_mdsc = false;
 
     dout("handle_cap_flushsnap_ack inode %p ci %p mds%d follows %lld\n",
          inode, ci, session->s_mds, follows);
 
     spin_lock(&ci->i_ceph_lock);
     list_for_each_entry(iter, &ci->i_cap_snaps, ci_item) {
         if (iter->follows == follows) {
             if (iter->cap_flush.tid != flush_tid) {
                 dout(" cap_snap %p follows %lld tid %lld !="
                      " %lld\n", iter, follows,
                      flush_tid, iter->cap_flush.tid);
                 break;
             }
             capsnap = iter;
             break;
         } else {
             dout(" skipping cap_snap %p follows %lld\n",
                  iter, iter->follows);
         }
     }
     if (capsnap)
         ceph_remove_capsnap(inode, capsnap, &wake_ci, &wake_mdsc);
     spin_unlock(&ci->i_ceph_lock);
 
     if (capsnap) {
         ceph_put_snap_context(capsnap->context);
         ceph_put_cap_snap(capsnap);
         if (wake_ci)
             wake_up_all(&ci->i_cap_wq);
         if (wake_mdsc)
             wake_up_all(&mdsc->cap_flushing_wq);
         iput(inode);
     }
 }
 
 /*
  * Handle TRUNC from MDS, indicating file truncation.
  *
  * caller hold s_mutex.
  */
 static bool handle_cap_trunc(struct inode *inode,
                  struct ceph_mds_caps *trunc,
                  struct ceph_mds_session *session)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int mds = session->s_mds;
     int seq = le32_to_cpu(trunc->seq);
     u32 truncate_seq = le32_to_cpu(trunc->truncate_seq);
     u64 truncate_size = le64_to_cpu(trunc->truncate_size);
     u64 size = le64_to_cpu(trunc->size);
     int implemented = 0;
     int dirty = __ceph_caps_dirty(ci);
     int issued = __ceph_caps_issued(ceph_inode(inode), &implemented);
     bool queue_trunc = false;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     issued |= implemented | dirty;
 
     dout("handle_cap_trunc inode %p mds%d seq %d to %lld seq %d\n",
          inode, mds, seq, truncate_size, truncate_seq);
     queue_trunc = ceph_fill_file_size(inode, issued,
                       truncate_seq, truncate_size, size);
     return queue_trunc;
 }
 
 /*
  * Handle EXPORT from MDS.  Cap is being migrated _from_ this mds to a
  * different one.  If we are the most recent migration we've seen (as
  * indicated by mseq), make note of the migrating cap bits for the
  * duration (until we see the corresponding IMPORT).
  *
  * caller holds s_mutex
  */
 static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
                   struct ceph_mds_cap_peer *ph,
                   struct ceph_mds_session *session)
 {
     struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
     struct ceph_mds_session *tsession = NULL;
     struct ceph_cap *cap, *tcap, *new_cap = NULL;
     struct ceph_inode_info *ci = ceph_inode(inode);
     u64 t_cap_id;
     unsigned mseq = le32_to_cpu(ex->migrate_seq);
     unsigned t_seq, t_mseq;
     int target, issued;
     int mds = session->s_mds;
 
     if (ph) {
         t_cap_id = le64_to_cpu(ph->cap_id);
         t_seq = le32_to_cpu(ph->seq);
         t_mseq = le32_to_cpu(ph->mseq);
         target = le32_to_cpu(ph->mds);
     } else {
         t_cap_id = t_seq = t_mseq = 0;
         target = -1;
     }
 
     dout("handle_cap_export inode %p ci %p mds%d mseq %d target %d\n",
          inode, ci, mds, mseq, target);
 retry:
     down_read(&mdsc->snap_rwsem);
     spin_lock(&ci->i_ceph_lock);
     cap = __get_cap_for_mds(ci, mds);
     if (!cap || cap->cap_id != le64_to_cpu(ex->cap_id))
         goto out_unlock;
 
     if (target < 0) {
         ceph_remove_cap(cap, false);
         goto out_unlock;
     }
 
     /*
      * now we know we haven't received the cap import message yet
      * because the exported cap still exist.
      */
 
     issued = cap->issued;
     if (issued != cap->implemented)
         pr_err_ratelimited("handle_cap_export: issued != implemented: "
                 "ino (%llx.%llx) mds%d seq %d mseq %d "
                 "issued %s implemented %s\n",
                 ceph_vinop(inode), mds, cap->seq, cap->mseq,
                 ceph_cap_string(issued),
                 ceph_cap_string(cap->implemented));
 
 
     tcap = __get_cap_for_mds(ci, target);
     if (tcap) {
         /* already have caps from the target */
         if (tcap->cap_id == t_cap_id &&
             ceph_seq_cmp(tcap->seq, t_seq) < 0) {
             dout(" updating import cap %p mds%d\n", tcap, target);
             tcap->cap_id = t_cap_id;
             tcap->seq = t_seq - 1;
             tcap->issue_seq = t_seq - 1;
             tcap->issued |= issued;
             tcap->implemented |= issued;
             if (cap == ci->i_auth_cap) {
                 ci->i_auth_cap = tcap;
                 change_auth_cap_ses(ci, tcap->session);
             }
         }
         ceph_remove_cap(cap, false);
         goto out_unlock;
     } else if (tsession) {
         /* add placeholder for the export tagert */
         int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
         tcap = new_cap;
         ceph_add_cap(inode, tsession, t_cap_id, issued, 0,
                  t_seq - 1, t_mseq, (u64)-1, flag, &new_cap);
 
         if (!list_empty(&ci->i_cap_flush_list) &&
             ci->i_auth_cap == tcap) {
             spin_lock(&mdsc->cap_dirty_lock);
             list_move_tail(&ci->i_flushing_item,
                        &tcap->session->s_cap_flushing);
             spin_unlock(&mdsc->cap_dirty_lock);
         }
 
         ceph_remove_cap(cap, false);
         goto out_unlock;
     }
 
     spin_unlock(&ci->i_ceph_lock);
     up_read(&mdsc->snap_rwsem);
     mutex_unlock(&session->s_mutex);
 
     /* open target session */
     tsession = ceph_mdsc_open_export_target_session(mdsc, target);
     if (!IS_ERR(tsession)) {
         if (mds > target) {
             mutex_lock(&session->s_mutex);
             mutex_lock_nested(&tsession->s_mutex,
                       SINGLE_DEPTH_NESTING);
         } else {
             mutex_lock(&tsession->s_mutex);
             mutex_lock_nested(&session->s_mutex,
                       SINGLE_DEPTH_NESTING);
         }
         new_cap = ceph_get_cap(mdsc, NULL);
     } else {
         WARN_ON(1);
         tsession = NULL;
         target = -1;
         mutex_lock(&session->s_mutex);
     }
     goto retry;
 
 out_unlock:
     spin_unlock(&ci->i_ceph_lock);
     up_read(&mdsc->snap_rwsem);
     mutex_unlock(&session->s_mutex);
     if (tsession) {
         mutex_unlock(&tsession->s_mutex);
         ceph_put_mds_session(tsession);
     }
     if (new_cap)
         ceph_put_cap(mdsc, new_cap);
 }
 
 /*
  * Handle cap IMPORT.
  *
  * caller holds s_mutex. acquires i_ceph_lock
  */
 static void handle_cap_import(struct ceph_mds_client *mdsc,
                   struct inode *inode, struct ceph_mds_caps *im,
                   struct ceph_mds_cap_peer *ph,
                   struct ceph_mds_session *session,
                   struct ceph_cap **target_cap, int *old_issued)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_cap *cap, *ocap, *new_cap = NULL;
     int mds = session->s_mds;
     int issued;
     unsigned caps = le32_to_cpu(im->caps);
     unsigned wanted = le32_to_cpu(im->wanted);
     unsigned seq = le32_to_cpu(im->seq);
     unsigned mseq = le32_to_cpu(im->migrate_seq);
     u64 realmino = le64_to_cpu(im->realm);
     u64 cap_id = le64_to_cpu(im->cap_id);
     u64 p_cap_id;
     int peer;
 
     if (ph) {
         p_cap_id = le64_to_cpu(ph->cap_id);
         peer = le32_to_cpu(ph->mds);
     } else {
         p_cap_id = 0;
         peer = -1;
     }
 
     dout("handle_cap_import inode %p ci %p mds%d mseq %d peer %d\n",
          inode, ci, mds, mseq, peer);
 retry:
     cap = __get_cap_for_mds(ci, mds);
     if (!cap) {
         if (!new_cap) {
             spin_unlock(&ci->i_ceph_lock);
             new_cap = ceph_get_cap(mdsc, NULL);
             spin_lock(&ci->i_ceph_lock);
             goto retry;
         }
         cap = new_cap;
     } else {
         if (new_cap) {
             ceph_put_cap(mdsc, new_cap);
             new_cap = NULL;
         }
     }
 
     __ceph_caps_issued(ci, &issued);
     issued |= __ceph_caps_dirty(ci);
 
     ceph_add_cap(inode, session, cap_id, caps, wanted, seq, mseq,
              realmino, CEPH_CAP_FLAG_AUTH, &new_cap);
 
     ocap = peer >= 0 ? __get_cap_for_mds(ci, peer) : NULL;
     if (ocap && ocap->cap_id == p_cap_id) {
         dout(" remove export cap %p mds%d flags %d\n",
              ocap, peer, ph->flags);
         if ((ph->flags & CEPH_CAP_FLAG_AUTH) &&
             (ocap->seq != le32_to_cpu(ph->seq) ||
              ocap->mseq != le32_to_cpu(ph->mseq))) {
             pr_err_ratelimited("handle_cap_import: "
                     "mismatched seq/mseq: ino (%llx.%llx) "
                     "mds%d seq %d mseq %d importer mds%d "
                     "has peer seq %d mseq %d\n",
                     ceph_vinop(inode), peer, ocap->seq,
                     ocap->mseq, mds, le32_to_cpu(ph->seq),
                     le32_to_cpu(ph->mseq));
         }
         ceph_remove_cap(ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
     }
 
     *old_issued = issued;
     *target_cap = cap;
 }
 
 /*
  * Handle a caps message from the MDS.
  *
  * Identify the appropriate session, inode, and call the right handler
  * based on the cap op.
  */
 void ceph_handle_caps(struct ceph_mds_session *session,
               struct ceph_msg *msg)
 {
     struct ceph_mds_client *mdsc = session->s_mdsc;
     struct inode *inode;
     struct ceph_inode_info *ci;
     struct ceph_cap *cap;
     struct ceph_mds_caps *h;
     struct ceph_mds_cap_peer *peer = NULL;
     struct ceph_snap_realm *realm = NULL;
     int op;
     int msg_version = le16_to_cpu(msg->hdr.version);
     u32 seq, mseq;
     struct ceph_vino vino;
     void *snaptrace;
     size_t snaptrace_len;
     void *p, *end;
     struct cap_extra_info extra_info = {};
     bool queue_trunc;
 
     dout("handle_caps from mds%d\n", session->s_mds);
 
     /* decode */
     end = msg->front.iov_base + msg->front.iov_len;
     if (msg->front.iov_len < sizeof(*h))
         goto bad;
     h = msg->front.iov_base;
     op = le32_to_cpu(h->op);
     vino.ino = le64_to_cpu(h->ino);
     vino.snap = CEPH_NOSNAP;
     seq = le32_to_cpu(h->seq);
     mseq = le32_to_cpu(h->migrate_seq);
 
     snaptrace = h + 1;
     snaptrace_len = le32_to_cpu(h->snap_trace_len);
     p = snaptrace + snaptrace_len;
 
     if (msg_version >= 2) {
         u32 flock_len;
         ceph_decode_32_safe(&p, end, flock_len, bad);
         if (p + flock_len > end)
             goto bad;
         p += flock_len;
     }
 
     if (msg_version >= 3) {
         if (op == CEPH_CAP_OP_IMPORT) {
             if (p + sizeof(*peer) > end)
                 goto bad;
             peer = p;
             p += sizeof(*peer);
         } else if (op == CEPH_CAP_OP_EXPORT) {
             /* recorded in unused fields */
             peer = (void *)&h->size;
         }
     }
 
     if (msg_version >= 4) {
         ceph_decode_64_safe(&p, end, extra_info.inline_version, bad);
         ceph_decode_32_safe(&p, end, extra_info.inline_len, bad);
         if (p + extra_info.inline_len > end)
             goto bad;
         extra_info.inline_data = p;
         p += extra_info.inline_len;
     }
 
     if (msg_version >= 5) {
         struct ceph_osd_client  *osdc = &mdsc->fsc->client->osdc;
         u32         epoch_barrier;
 
         ceph_decode_32_safe(&p, end, epoch_barrier, bad);
         ceph_osdc_update_epoch_barrier(osdc, epoch_barrier);
     }
 
     if (msg_version >= 8) {
         u32 pool_ns_len;
 
         /* version >= 6 */
         ceph_decode_skip_64(&p, end, bad);  // flush_tid
         /* version >= 7 */
         ceph_decode_skip_32(&p, end, bad);  // caller_uid
         ceph_decode_skip_32(&p, end, bad);  // caller_gid
         /* version >= 8 */
         ceph_decode_32_safe(&p, end, pool_ns_len, bad);
         if (pool_ns_len > 0) {
             ceph_decode_need(&p, end, pool_ns_len, bad);
             extra_info.pool_ns =
                 ceph_find_or_create_string(p, pool_ns_len);
             p += pool_ns_len;
         }
     }
 
     if (msg_version >= 9) {
         struct ceph_timespec *btime;
 
         if (p + sizeof(*btime) > end)
             goto bad;
         btime = p;
         ceph_decode_timespec64(&extra_info.btime, btime);
         p += sizeof(*btime);
         ceph_decode_64_safe(&p, end, extra_info.change_attr, bad);
     }
 
     if (msg_version >= 11) {
         /* version >= 10 */
         ceph_decode_skip_32(&p, end, bad); // flags
         /* version >= 11 */
         extra_info.dirstat_valid = true;
         ceph_decode_64_safe(&p, end, extra_info.nfiles, bad);
         ceph_decode_64_safe(&p, end, extra_info.nsubdirs, bad);
     }
 
     /* lookup ino */
     inode = ceph_find_inode(mdsc->fsc->sb, vino);
     dout(" op %s ino %llx.%llx inode %p\n", ceph_cap_op_name(op), vino.ino,
          vino.snap, inode);
 
     mutex_lock(&session->s_mutex);
     inc_session_sequence(session);
     dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq,
          (unsigned)seq);
 
     if (!inode) {
         dout(" i don't have ino %llx\n", vino.ino);
 
         if (op == CEPH_CAP_OP_IMPORT) {
             cap = ceph_get_cap(mdsc, NULL);
             cap->cap_ino = vino.ino;
             cap->queue_release = 1;
             cap->cap_id = le64_to_cpu(h->cap_id);
             cap->mseq = mseq;
             cap->seq = seq;
             cap->issue_seq = seq;
             spin_lock(&session->s_cap_lock);
             __ceph_queue_cap_release(session, cap);
             spin_unlock(&session->s_cap_lock);
         }
         goto flush_cap_releases;
     }
     ci = ceph_inode(inode);
 
     /* these will work even if we don't have a cap yet */
     switch (op) {
     case CEPH_CAP_OP_FLUSHSNAP_ACK:
         handle_cap_flushsnap_ack(inode, le64_to_cpu(msg->hdr.tid),
                      h, session);
         goto done;
 
     case CEPH_CAP_OP_EXPORT:
         handle_cap_export(inode, h, peer, session);
         goto done_unlocked;
 
     case CEPH_CAP_OP_IMPORT:
         realm = NULL;
         if (snaptrace_len) {
             down_write(&mdsc->snap_rwsem);
             ceph_update_snap_trace(mdsc, snaptrace,
                            snaptrace + snaptrace_len,
                            false, &realm);
             downgrade_write(&mdsc->snap_rwsem);
         } else {
             down_read(&mdsc->snap_rwsem);
         }
         spin_lock(&ci->i_ceph_lock);
         handle_cap_import(mdsc, inode, h, peer, session,
                   &cap, &extra_info.issued);
         handle_cap_grant(inode, session, cap,
                  h, msg->middle, &extra_info);
         if (realm)
             ceph_put_snap_realm(mdsc, realm);
         goto done_unlocked;
     }
 
     /* the rest require a cap */
     spin_lock(&ci->i_ceph_lock);
     cap = __get_cap_for_mds(ceph_inode(inode), session->s_mds);
     if (!cap) {
         dout(" no cap on %p ino %llx.%llx from mds%d\n",
              inode, ceph_ino(inode), ceph_snap(inode),
              session->s_mds);
         spin_unlock(&ci->i_ceph_lock);
         goto flush_cap_releases;
     }
 
     /* note that each of these drops i_ceph_lock for us */
     switch (op) {
     case CEPH_CAP_OP_REVOKE:
     case CEPH_CAP_OP_GRANT:
         __ceph_caps_issued(ci, &extra_info.issued);
         extra_info.issued |= __ceph_caps_dirty(ci);
         handle_cap_grant(inode, session, cap,
                  h, msg->middle, &extra_info);
         goto done_unlocked;
 
     case CEPH_CAP_OP_FLUSH_ACK:
         handle_cap_flush_ack(inode, le64_to_cpu(msg->hdr.tid),
                      h, session, cap);
         break;
 
     case CEPH_CAP_OP_TRUNC:
         queue_trunc = handle_cap_trunc(inode, h, session);
         spin_unlock(&ci->i_ceph_lock);
         if (queue_trunc)
             ceph_queue_vmtruncate(inode);
         break;
 
     default:
         spin_unlock(&ci->i_ceph_lock);
         pr_err("ceph_handle_caps: unknown cap op %d %s\n", op,
                ceph_cap_op_name(op));
     }
 
 done:
     mutex_unlock(&session->s_mutex);
 done_unlocked:
     iput(inode);
 out:
     ceph_put_string(extra_info.pool_ns);
     return;
 
 flush_cap_releases:
     /*
      * send any cap release message to try to move things
      * along for the mds (who clearly thinks we still have this
      * cap).
      */
     ceph_flush_cap_releases(mdsc, session);
     goto done;
 
 bad:
     pr_err("ceph_handle_caps: corrupt message\n");
     ceph_msg_dump(msg);
     goto out;
 }
 
 /*
  * Delayed work handler to process end of delayed cap release LRU list.
  *
  * If new caps are added to the list while processing it, these won't get
  * processed in this run.  In this case, the ci->i_hold_caps_max will be
  * returned so that the work can be scheduled accordingly.
  */
 unsigned long ceph_check_delayed_caps(struct ceph_mds_client *mdsc)
 {
     struct inode *inode;
     struct ceph_inode_info *ci;
     struct ceph_mount_options *opt = mdsc->fsc->mount_options;
     unsigned long delay_max = opt->caps_wanted_delay_max * HZ;
     unsigned long loop_start = jiffies;
     unsigned long delay = 0;
 
     dout("check_delayed_caps\n");
     spin_lock(&mdsc->cap_delay_lock);
     while (!list_empty(&mdsc->cap_delay_list)) {
         ci = list_first_entry(&mdsc->cap_delay_list,
                       struct ceph_inode_info,
                       i_cap_delay_list);
         if (time_before(loop_start, ci->i_hold_caps_max - delay_max)) {
             dout("%s caps added recently.  Exiting loop", __func__);
             delay = ci->i_hold_caps_max;
             break;
         }
         if ((ci->i_ceph_flags & CEPH_I_FLUSH) == 0 &&
             time_before(jiffies, ci->i_hold_caps_max))
             break;
         list_del_init(&ci->i_cap_delay_list);
 
         inode = igrab(&ci->netfs.inode);
         if (inode) {
             spin_unlock(&mdsc->cap_delay_lock);
             dout("check_delayed_caps on %p\n", inode);
             ceph_check_caps(ci, 0, NULL);
             iput(inode);
             spin_lock(&mdsc->cap_delay_lock);
         }
     }
     spin_unlock(&mdsc->cap_delay_lock);
 
     return delay;
 }
 
 /*
  * Flush all dirty caps to the mds
  */
 static void flush_dirty_session_caps(struct ceph_mds_session *s)
 {
     struct ceph_mds_client *mdsc = s->s_mdsc;
     struct ceph_inode_info *ci;
     struct inode *inode;
 
     dout("flush_dirty_caps\n");
     spin_lock(&mdsc->cap_dirty_lock);
     while (!list_empty(&s->s_cap_dirty)) {
         ci = list_first_entry(&s->s_cap_dirty, struct ceph_inode_info,
                       i_dirty_item);
         inode = &ci->netfs.inode;
         ihold(inode);
         dout("flush_dirty_caps %llx.%llx\n", ceph_vinop(inode));
         spin_unlock(&mdsc->cap_dirty_lock);
         ceph_wait_on_async_create(inode);
         ceph_check_caps(ci, CHECK_CAPS_FLUSH, NULL);
         iput(inode);
         spin_lock(&mdsc->cap_dirty_lock);
     }
     spin_unlock(&mdsc->cap_dirty_lock);
     dout("flush_dirty_caps done\n");
 }
 
 void ceph_flush_dirty_caps(struct ceph_mds_client *mdsc)
 {
     ceph_mdsc_iterate_sessions(mdsc, flush_dirty_session_caps, true);
 }
 
 void __ceph_touch_fmode(struct ceph_inode_info *ci,
             struct ceph_mds_client *mdsc, int fmode)
 {
     unsigned long now = jiffies;
     if (fmode & CEPH_FILE_MODE_RD)
         ci->i_last_rd = now;
     if (fmode & CEPH_FILE_MODE_WR)
         ci->i_last_wr = now;
     /* queue periodic check */
     if (fmode &&
         __ceph_is_any_real_caps(ci) &&
         list_empty(&ci->i_cap_delay_list))
         __cap_delay_requeue(mdsc, ci);
 }
 
 void ceph_get_fmode(struct ceph_inode_info *ci, int fmode, int count)
 {
     struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->netfs.inode.i_sb);
     int bits = (fmode << 1) | 1;
     bool already_opened = false;
     int i;
 
     if (count == 1)
         atomic64_inc(&mdsc->metric.opened_files);
 
     spin_lock(&ci->i_ceph_lock);
     for (i = 0; i < CEPH_FILE_MODE_BITS; i++) {
         /*
          * If any of the mode ref is larger than 0,
          * that means it has been already opened by
          * others. Just skip checking the PIN ref.
          */
         if (i && ci->i_nr_by_mode[i])
             already_opened = true;
 
         if (bits & (1 << i))
             ci->i_nr_by_mode[i] += count;
     }
 
     if (!already_opened)
         percpu_counter_inc(&mdsc->metric.opened_inodes);
     spin_unlock(&ci->i_ceph_lock);
 }
 
 /*
  * Drop open file reference.  If we were the last open file,
  * we may need to release capabilities to the MDS (or schedule
  * their delayed release).
  */
 void ceph_put_fmode(struct ceph_inode_info *ci, int fmode, int count)
 {
     struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->netfs.inode.i_sb);
     int bits = (fmode << 1) | 1;
     bool is_closed = true;
     int i;
 
     if (count == 1)
         atomic64_dec(&mdsc->metric.opened_files);
 
     spin_lock(&ci->i_ceph_lock);
     for (i = 0; i < CEPH_FILE_MODE_BITS; i++) {
         if (bits & (1 << i)) {
             BUG_ON(ci->i_nr_by_mode[i] < count);
             ci->i_nr_by_mode[i] -= count;
         }
 
         /*
          * If any of the mode ref is not 0 after
          * decreased, that means it is still opened
          * by others. Just skip checking the PIN ref.
          */
         if (i && ci->i_nr_by_mode[i])
             is_closed = false;
     }
 
     if (is_closed)
         percpu_counter_dec(&mdsc->metric.opened_inodes);
     spin_unlock(&ci->i_ceph_lock);
 }
 
 /*
  * For a soon-to-be unlinked file, drop the LINK caps. If it
  * looks like the link count will hit 0, drop any other caps (other
  * than PIN) we don't specifically want (due to the file still being
  * open).
  */
 int ceph_drop_caps_for_unlink(struct inode *inode)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     int drop = CEPH_CAP_LINK_SHARED | CEPH_CAP_LINK_EXCL;
 
     spin_lock(&ci->i_ceph_lock);
     if (inode->i_nlink == 1) {
         drop |= ~(__ceph_caps_wanted(ci) | CEPH_CAP_PIN);
 
         if (__ceph_caps_dirty(ci)) {
             struct ceph_mds_client *mdsc =
                 ceph_inode_to_client(inode)->mdsc;
             __cap_delay_requeue_front(mdsc, ci);
         }
     }
     spin_unlock(&ci->i_ceph_lock);
     return drop;
 }
 
 /*
  * Helpers for embedding cap and dentry lease releases into mds
  * requests.
  *
  * @force is used by dentry_release (below) to force inclusion of a
  * record for the directory inode, even when there aren't any caps to
  * drop.
  */
 int ceph_encode_inode_release(void **p, struct inode *inode,
                   int mds, int drop, int unless, int force)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_cap *cap;
     struct ceph_mds_request_release *rel = *p;
     int used, dirty;
     int ret = 0;
 
     spin_lock(&ci->i_ceph_lock);
     used = __ceph_caps_used(ci);
     dirty = __ceph_caps_dirty(ci);
 
     dout("encode_inode_release %p mds%d used|dirty %s drop %s unless %s\n",
          inode, mds, ceph_cap_string(used|dirty), ceph_cap_string(drop),
          ceph_cap_string(unless));
 
     /* only drop unused, clean caps */
     drop &= ~(used | dirty);
 
     cap = __get_cap_for_mds(ci, mds);
     if (cap && __cap_is_valid(cap)) {
         unless &= cap->issued;
         if (unless) {
             if (unless & CEPH_CAP_AUTH_EXCL)
                 drop &= ~CEPH_CAP_AUTH_SHARED;
             if (unless & CEPH_CAP_LINK_EXCL)
                 drop &= ~CEPH_CAP_LINK_SHARED;
             if (unless & CEPH_CAP_XATTR_EXCL)
                 drop &= ~CEPH_CAP_XATTR_SHARED;
             if (unless & CEPH_CAP_FILE_EXCL)
                 drop &= ~CEPH_CAP_FILE_SHARED;
         }
 
         if (force || (cap->issued & drop)) {
             if (cap->issued & drop) {
                 int wanted = __ceph_caps_wanted(ci);
                 dout("encode_inode_release %p cap %p "
                      "%s -> %s, wanted %s -> %s\n", inode, cap,
                      ceph_cap_string(cap->issued),
                      ceph_cap_string(cap->issued & ~drop),
                      ceph_cap_string(cap->mds_wanted),
                      ceph_cap_string(wanted));
 
                 cap->issued &= ~drop;
                 cap->implemented &= ~drop;
                 cap->mds_wanted = wanted;
                 if (cap == ci->i_auth_cap &&
                     !(wanted & CEPH_CAP_ANY_FILE_WR))
                     ci->i_requested_max_size = 0;
             } else {
                 dout("encode_inode_release %p cap %p %s"
                      " (force)\n", inode, cap,
                      ceph_cap_string(cap->issued));
             }
 
             rel->ino = cpu_to_le64(ceph_ino(inode));
             rel->cap_id = cpu_to_le64(cap->cap_id);
             rel->seq = cpu_to_le32(cap->seq);
             rel->issue_seq = cpu_to_le32(cap->issue_seq);
             rel->mseq = cpu_to_le32(cap->mseq);
             rel->caps = cpu_to_le32(cap->implemented);
             rel->wanted = cpu_to_le32(cap->mds_wanted);
             rel->dname_len = 0;
             rel->dname_seq = 0;
             *p += sizeof(*rel);
             ret = 1;
         } else {
             dout("encode_inode_release %p cap %p %s (noop)\n",
                  inode, cap, ceph_cap_string(cap->issued));
         }
     }
     spin_unlock(&ci->i_ceph_lock);
     return ret;
 }
 
 int ceph_encode_dentry_release(void **p, struct dentry *dentry,
                    struct inode *dir,
                    int mds, int drop, int unless)
 {
     struct dentry *parent = NULL;
     struct ceph_mds_request_release *rel = *p;
     struct ceph_dentry_info *di = ceph_dentry(dentry);
     int force = 0;
     int ret;
 
     /*
      * force an record for the directory caps if we have a dentry lease.
      * this is racy (can't take i_ceph_lock and d_lock together), but it
      * doesn't have to be perfect; the mds will revoke anything we don't
      * release.
      */
     spin_lock(&dentry->d_lock);
     if (di->lease_session && di->lease_session->s_mds == mds)
         force = 1;
     if (!dir) {
         parent = dget(dentry->d_parent);
         dir = d_inode(parent);
     }
     spin_unlock(&dentry->d_lock);
 
     ret = ceph_encode_inode_release(p, dir, mds, drop, unless, force);
     dput(parent);
 
     spin_lock(&dentry->d_lock);
     if (ret && di->lease_session && di->lease_session->s_mds == mds) {
         dout("encode_dentry_release %p mds%d seq %d\n",
              dentry, mds, (int)di->lease_seq);
         rel->dname_len = cpu_to_le32(dentry->d_name.len);
         memcpy(*p, dentry->d_name.name, dentry->d_name.len);
         *p += dentry->d_name.len;
         rel->dname_seq = cpu_to_le32(di->lease_seq);
         __ceph_mdsc_drop_dentry_lease(dentry);
     }
     spin_unlock(&dentry->d_lock);
     return ret;
 }
 
 static int remove_capsnaps(struct ceph_mds_client *mdsc, struct inode *inode)
 {
     struct ceph_inode_info *ci = ceph_inode(inode);
     struct ceph_cap_snap *capsnap;
     int capsnap_release = 0;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("removing capsnaps, ci is %p, inode is %p\n", ci, inode);
 
     while (!list_empty(&ci->i_cap_snaps)) {
         capsnap = list_first_entry(&ci->i_cap_snaps,
                        struct ceph_cap_snap, ci_item);
         __ceph_remove_capsnap(inode, capsnap, NULL, NULL);
         ceph_put_snap_context(capsnap->context);
         ceph_put_cap_snap(capsnap);
         capsnap_release++;
     }
     wake_up_all(&ci->i_cap_wq);
     wake_up_all(&mdsc->cap_flushing_wq);
     return capsnap_release;
 }
 
 int ceph_purge_inode_cap(struct inode *inode, struct ceph_cap *cap, bool *invalidate)
 {
     struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
     struct ceph_mds_client *mdsc = fsc->mdsc;
     struct ceph_inode_info *ci = ceph_inode(inode);
     bool is_auth;
     bool dirty_dropped = false;
     int iputs = 0;
 
     lockdep_assert_held(&ci->i_ceph_lock);
 
     dout("removing cap %p, ci is %p, inode is %p\n",
          cap, ci, &ci->netfs.inode);
 
     is_auth = (cap == ci->i_auth_cap);
     __ceph_remove_cap(cap, false);
     if (is_auth) {
         struct ceph_cap_flush *cf;
 
         if (ceph_inode_is_shutdown(inode)) {
             if (inode->i_data.nrpages > 0)
                 *invalidate = true;
             if (ci->i_wrbuffer_ref > 0)
                 mapping_set_error(&inode->i_data, -EIO);
         }
 
         spin_lock(&mdsc->cap_dirty_lock);
 
         /* trash all of the cap flushes for this inode */
         while (!list_empty(&ci->i_cap_flush_list)) {
             cf = list_first_entry(&ci->i_cap_flush_list,
                           struct ceph_cap_flush, i_list);
             list_del_init(&cf->g_list);
             list_del_init(&cf->i_list);
             if (!cf->is_capsnap)
                 ceph_free_cap_flush(cf);
         }
 
         if (!list_empty(&ci->i_dirty_item)) {
             pr_warn_ratelimited(
                 " dropping dirty %s state for %p %lld\n",
                 ceph_cap_string(ci->i_dirty_caps),
                 inode, ceph_ino(inode));
             ci->i_dirty_caps = 0;
             list_del_init(&ci->i_dirty_item);
             dirty_dropped = true;
         }
         if (!list_empty(&ci->i_flushing_item)) {
             pr_warn_ratelimited(
                 " dropping dirty+flushing %s state for %p %lld\n",
                 ceph_cap_string(ci->i_flushing_caps),
                 inode, ceph_ino(inode));
             ci->i_flushing_caps = 0;
             list_del_init(&ci->i_flushing_item);
             mdsc->num_cap_flushing--;
             dirty_dropped = true;
         }
         spin_unlock(&mdsc->cap_dirty_lock);
 
         if (dirty_dropped) {
             mapping_set_error(inode->i_mapping, -EIO);
 
             if (ci->i_wrbuffer_ref_head == 0 &&
                 ci->i_wr_ref == 0 &&
                 ci->i_dirty_caps == 0 &&
                 ci->i_flushing_caps == 0) {
                 ceph_put_snap_context(ci->i_head_snapc);
                 ci->i_head_snapc = NULL;
             }
         }
 
         if (atomic_read(&ci->i_filelock_ref) > 0) {
             /* make further file lock syscall return -EIO */
             ci->i_ceph_flags |= CEPH_I_ERROR_FILELOCK;
             pr_warn_ratelimited(" dropping file locks for %p %lld\n",
                         inode, ceph_ino(inode));
         }
 
         if (!ci->i_dirty_caps && ci->i_prealloc_cap_flush) {
             cf = ci->i_prealloc_cap_flush;
             ci->i_prealloc_cap_flush = NULL;
             if (!cf->is_capsnap)
                 ceph_free_cap_flush(cf);
         }
 
         if (!list_empty(&ci->i_cap_snaps))
             iputs = remove_capsnaps(mdsc, inode);
     }
     if (dirty_dropped)
         ++iputs;
     return iputs;
 }