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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-or-later
 /* AFS file locking support
  *
  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */
 
 #include "internal.h"
 
 #define AFS_LOCK_GRANTED    0
 #define AFS_LOCK_PENDING    1
 #define AFS_LOCK_YOUR_TRY   2
 
 struct workqueue_struct *afs_lock_manager;
 
 static void afs_next_locker(struct afs_vnode *vnode, int error);
 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
 static void afs_fl_release_private(struct file_lock *fl);
 
 static const struct file_lock_operations afs_lock_ops = {
     .fl_copy_lock       = afs_fl_copy_lock,
     .fl_release_private = afs_fl_release_private,
 };
 
 static inline void afs_set_lock_state(struct afs_vnode *vnode, enum afs_lock_state state)
 {
     _debug("STATE %u -> %u", vnode->lock_state, state);
     vnode->lock_state = state;
 }
 
 static atomic_t afs_file_lock_debug_id;
 
 /*
  * if the callback is broken on this vnode, then the lock may now be available
  */
 void afs_lock_may_be_available(struct afs_vnode *vnode)
 {
     _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
 
     spin_lock(&vnode->lock);
     if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
         afs_next_locker(vnode, 0);
     trace_afs_flock_ev(vnode, NULL, afs_flock_callback_break, 0);
     spin_unlock(&vnode->lock);
 }
 
 /*
  * the lock will time out in 5 minutes unless we extend it, so schedule
  * extension in a bit less than that time
  */
 static void afs_schedule_lock_extension(struct afs_vnode *vnode)
 {
     ktime_t expires_at, now, duration;
     u64 duration_j;
 
     expires_at = ktime_add_ms(vnode->locked_at, AFS_LOCKWAIT * 1000 / 2);
     now = ktime_get_real();
     duration = ktime_sub(expires_at, now);
     if (duration <= 0)
         duration_j = 0;
     else
         duration_j = nsecs_to_jiffies(ktime_to_ns(duration));
 
     queue_delayed_work(afs_lock_manager, &vnode->lock_work, duration_j);
 }
 
 /*
  * In the case of successful completion of a lock operation, record the time
  * the reply appeared and start the lock extension timer.
  */
 void afs_lock_op_done(struct afs_call *call)
 {
     struct afs_operation *op = call->op;
     struct afs_vnode *vnode = op->file[0].vnode;
 
     if (call->error == 0) {
         spin_lock(&vnode->lock);
         trace_afs_flock_ev(vnode, NULL, afs_flock_timestamp, 0);
         vnode->locked_at = call->issue_time;
         afs_schedule_lock_extension(vnode);
         spin_unlock(&vnode->lock);
     }
 }
 
 /*
  * grant one or more locks (readlocks are allowed to jump the queue if the
  * first lock in the queue is itself a readlock)
  * - the caller must hold the vnode lock
  */
 static void afs_grant_locks(struct afs_vnode *vnode)
 {
     struct file_lock *p, *_p;
     bool exclusive = (vnode->lock_type == AFS_LOCK_WRITE);
 
     list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
         if (!exclusive && p->fl_type == F_WRLCK)
             continue;
 
         list_move_tail(&p->fl_u.afs.link, &vnode->granted_locks);
         p->fl_u.afs.state = AFS_LOCK_GRANTED;
         trace_afs_flock_op(vnode, p, afs_flock_op_grant);
         wake_up(&p->fl_wait);
     }
 }
 
 /*
  * If an error is specified, reject every pending lock that matches the
  * authentication and type of the lock we failed to get.  If there are any
  * remaining lockers, try to wake up one of them to have a go.
  */
 static void afs_next_locker(struct afs_vnode *vnode, int error)
 {
     struct file_lock *p, *_p, *next = NULL;
     struct key *key = vnode->lock_key;
     unsigned int fl_type = F_RDLCK;
 
     _enter("");
 
     if (vnode->lock_type == AFS_LOCK_WRITE)
         fl_type = F_WRLCK;
 
     list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
         if (error &&
             p->fl_type == fl_type &&
             afs_file_key(p->fl_file) == key) {
             list_del_init(&p->fl_u.afs.link);
             p->fl_u.afs.state = error;
             wake_up(&p->fl_wait);
         }
 
         /* Select the next locker to hand off to. */
         if (next &&
             (next->fl_type == F_WRLCK || p->fl_type == F_RDLCK))
             continue;
         next = p;
     }
 
     vnode->lock_key = NULL;
     key_put(key);
 
     if (next) {
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
         next->fl_u.afs.state = AFS_LOCK_YOUR_TRY;
         trace_afs_flock_op(vnode, next, afs_flock_op_wake);
         wake_up(&next->fl_wait);
     } else {
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_NONE);
         trace_afs_flock_ev(vnode, NULL, afs_flock_no_lockers, 0);
     }
 
     _leave("");
 }
 
 /*
  * Kill off all waiters in the the pending lock queue due to the vnode being
  * deleted.
  */
 static void afs_kill_lockers_enoent(struct afs_vnode *vnode)
 {
     struct file_lock *p;
 
     afs_set_lock_state(vnode, AFS_VNODE_LOCK_DELETED);
 
     while (!list_empty(&vnode->pending_locks)) {
         p = list_entry(vnode->pending_locks.next,
                    struct file_lock, fl_u.afs.link);
         list_del_init(&p->fl_u.afs.link);
         p->fl_u.afs.state = -ENOENT;
         wake_up(&p->fl_wait);
     }
 
     key_put(vnode->lock_key);
     vnode->lock_key = NULL;
 }
 
 static void afs_lock_success(struct afs_operation *op)
 {
     _enter("op=%08x", op->debug_id);
     afs_vnode_commit_status(op, &op->file[0]);
 }
 
 static const struct afs_operation_ops afs_set_lock_operation = {
     .issue_afs_rpc  = afs_fs_set_lock,
     .issue_yfs_rpc  = yfs_fs_set_lock,
     .success    = afs_lock_success,
     .aborted    = afs_check_for_remote_deletion,
 };
 
 /*
  * Get a lock on a file
  */
 static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
             afs_lock_type_t type)
 {
     struct afs_operation *op;
 
     _enter("%s{%llx:%llu.%u},%x,%u",
            vnode->volume->name,
            vnode->fid.vid,
            vnode->fid.vnode,
            vnode->fid.unique,
            key_serial(key), type);
 
     op = afs_alloc_operation(key, vnode->volume);
     if (IS_ERR(op))
         return PTR_ERR(op);
 
     afs_op_set_vnode(op, 0, vnode);
 
     op->lock.type   = type;
     op->ops     = &afs_set_lock_operation;
     return afs_do_sync_operation(op);
 }
 
 static const struct afs_operation_ops afs_extend_lock_operation = {
     .issue_afs_rpc  = afs_fs_extend_lock,
     .issue_yfs_rpc  = yfs_fs_extend_lock,
     .success    = afs_lock_success,
 };
 
 /*
  * Extend a lock on a file
  */
 static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
 {
     struct afs_operation *op;
 
     _enter("%s{%llx:%llu.%u},%x",
            vnode->volume->name,
            vnode->fid.vid,
            vnode->fid.vnode,
            vnode->fid.unique,
            key_serial(key));
 
     op = afs_alloc_operation(key, vnode->volume);
     if (IS_ERR(op))
         return PTR_ERR(op);
 
     afs_op_set_vnode(op, 0, vnode);
 
     op->flags   |= AFS_OPERATION_UNINTR;
     op->ops     = &afs_extend_lock_operation;
     return afs_do_sync_operation(op);
 }
 
 static const struct afs_operation_ops afs_release_lock_operation = {
     .issue_afs_rpc  = afs_fs_release_lock,
     .issue_yfs_rpc  = yfs_fs_release_lock,
     .success    = afs_lock_success,
 };
 
 /*
  * Release a lock on a file
  */
 static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
 {
     struct afs_operation *op;
 
     _enter("%s{%llx:%llu.%u},%x",
            vnode->volume->name,
            vnode->fid.vid,
            vnode->fid.vnode,
            vnode->fid.unique,
            key_serial(key));
 
     op = afs_alloc_operation(key, vnode->volume);
     if (IS_ERR(op))
         return PTR_ERR(op);
 
     afs_op_set_vnode(op, 0, vnode);
 
     op->flags   |= AFS_OPERATION_UNINTR;
     op->ops     = &afs_release_lock_operation;
     return afs_do_sync_operation(op);
 }
 
 /*
  * do work for a lock, including:
  * - probing for a lock we're waiting on but didn't get immediately
  * - extending a lock that's close to timing out
  */
 void afs_lock_work(struct work_struct *work)
 {
     struct afs_vnode *vnode =
         container_of(work, struct afs_vnode, lock_work.work);
     struct key *key;
     int ret;
 
     _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
 
     spin_lock(&vnode->lock);
 
 again:
     _debug("wstate %u for %p", vnode->lock_state, vnode);
     switch (vnode->lock_state) {
     case AFS_VNODE_LOCK_NEED_UNLOCK:
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_UNLOCKING);
         trace_afs_flock_ev(vnode, NULL, afs_flock_work_unlocking, 0);
         spin_unlock(&vnode->lock);
 
         /* attempt to release the server lock; if it fails, we just
          * wait 5 minutes and it'll expire anyway */
         ret = afs_release_lock(vnode, vnode->lock_key);
         if (ret < 0 && vnode->lock_state != AFS_VNODE_LOCK_DELETED) {
             trace_afs_flock_ev(vnode, NULL, afs_flock_release_fail,
                        ret);
             printk(KERN_WARNING "AFS:"
                    " Failed to release lock on {%llx:%llx} error %d\n",
                    vnode->fid.vid, vnode->fid.vnode, ret);
         }
 
         spin_lock(&vnode->lock);
         if (ret == -ENOENT)
             afs_kill_lockers_enoent(vnode);
         else
             afs_next_locker(vnode, 0);
         spin_unlock(&vnode->lock);
         return;
 
     /* If we've already got a lock, then it must be time to extend that
      * lock as AFS locks time out after 5 minutes.
      */
     case AFS_VNODE_LOCK_GRANTED:
         _debug("extend");
 
         ASSERT(!list_empty(&vnode->granted_locks));
 
         key = key_get(vnode->lock_key);
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_EXTENDING);
         trace_afs_flock_ev(vnode, NULL, afs_flock_work_extending, 0);
         spin_unlock(&vnode->lock);
 
         ret = afs_extend_lock(vnode, key); /* RPC */
         key_put(key);
 
         if (ret < 0) {
             trace_afs_flock_ev(vnode, NULL, afs_flock_extend_fail,
                        ret);
             pr_warn("AFS: Failed to extend lock on {%llx:%llx} error %d\n",
                 vnode->fid.vid, vnode->fid.vnode, ret);
         }
 
         spin_lock(&vnode->lock);
 
         if (ret == -ENOENT) {
             afs_kill_lockers_enoent(vnode);
             spin_unlock(&vnode->lock);
             return;
         }
 
         if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
             goto again;
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
 
         if (ret != 0)
             queue_delayed_work(afs_lock_manager, &vnode->lock_work,
                        HZ * 10);
         spin_unlock(&vnode->lock);
         _leave(" [ext]");
         return;
 
     /* If we're waiting for a callback to indicate lock release, we can't
      * actually rely on this, so need to recheck at regular intervals.  The
      * problem is that the server might not notify us if the lock just
      * expires (say because a client died) rather than being explicitly
      * released.
      */
     case AFS_VNODE_LOCK_WAITING_FOR_CB:
         _debug("retry");
         afs_next_locker(vnode, 0);
         spin_unlock(&vnode->lock);
         return;
 
     case AFS_VNODE_LOCK_DELETED:
         afs_kill_lockers_enoent(vnode);
         spin_unlock(&vnode->lock);
         return;
 
     default:
         /* Looks like a lock request was withdrawn. */
         spin_unlock(&vnode->lock);
         _leave(" [no]");
         return;
     }
 }
 
 /*
  * pass responsibility for the unlocking of a vnode on the server to the
  * manager thread, lest a pending signal in the calling thread interrupt
  * AF_RXRPC
  * - the caller must hold the vnode lock
  */
 static void afs_defer_unlock(struct afs_vnode *vnode)
 {
     _enter("%u", vnode->lock_state);
 
     if (list_empty(&vnode->granted_locks) &&
         (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
          vnode->lock_state == AFS_VNODE_LOCK_EXTENDING)) {
         cancel_delayed_work(&vnode->lock_work);
 
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_NEED_UNLOCK);
         trace_afs_flock_ev(vnode, NULL, afs_flock_defer_unlock, 0);
         queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
     }
 }
 
 /*
  * Check that our view of the file metadata is up to date and check to see
  * whether we think that we have a locking permit.
  */
 static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
                   enum afs_flock_mode mode, afs_lock_type_t type)
 {
     afs_access_t access;
     int ret;
 
     /* Make sure we've got a callback on this file and that our view of the
      * data version is up to date.
      */
     ret = afs_validate(vnode, key);
     if (ret < 0)
         return ret;
 
     /* Check the permission set to see if we're actually going to be
      * allowed to get a lock on this file.
      */
     ret = afs_check_permit(vnode, key, &access);
     if (ret < 0)
         return ret;
 
     /* At a rough estimation, you need LOCK, WRITE or INSERT perm to
      * read-lock a file and WRITE or INSERT perm to write-lock a file.
      *
      * We can't rely on the server to do this for us since if we want to
      * share a read lock that we already have, we won't go the server.
      */
     if (type == AFS_LOCK_READ) {
         if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
             return -EACCES;
     } else {
         if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
             return -EACCES;
     }
 
     return 0;
 }
 
 /*
  * request a lock on a file on the server
  */
 static int afs_do_setlk(struct file *file, struct file_lock *fl)
 {
     struct inode *inode = locks_inode(file);
     struct afs_vnode *vnode = AFS_FS_I(inode);
     enum afs_flock_mode mode = AFS_FS_S(inode->i_sb)->flock_mode;
     afs_lock_type_t type;
     struct key *key = afs_file_key(file);
     bool partial, no_server_lock = false;
     int ret;
 
     if (mode == afs_flock_mode_unset)
         mode = afs_flock_mode_openafs;
 
     _enter("{%llx:%llu},%llu-%llu,%u,%u",
            vnode->fid.vid, vnode->fid.vnode,
            fl->fl_start, fl->fl_end, fl->fl_type, mode);
 
     fl->fl_ops = &afs_lock_ops;
     INIT_LIST_HEAD(&fl->fl_u.afs.link);
     fl->fl_u.afs.state = AFS_LOCK_PENDING;
 
     partial = (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX);
     type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
     if (mode == afs_flock_mode_write && partial)
         type = AFS_LOCK_WRITE;
 
     ret = afs_do_setlk_check(vnode, key, mode, type);
     if (ret < 0)
         return ret;
 
     trace_afs_flock_op(vnode, fl, afs_flock_op_set_lock);
 
     /* AFS3 protocol only supports full-file locks and doesn't provide any
      * method of upgrade/downgrade, so we need to emulate for partial-file
      * locks.
      *
      * The OpenAFS client only gets a server lock for a full-file lock and
      * keeps partial-file locks local.  Allow this behaviour to be emulated
      * (as the default).
      */
     if (mode == afs_flock_mode_local ||
         (partial && mode == afs_flock_mode_openafs)) {
         no_server_lock = true;
         goto skip_server_lock;
     }
 
     spin_lock(&vnode->lock);
     list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
 
     ret = -ENOENT;
     if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
         goto error_unlock;
 
     /* If we've already got a lock on the server then try to move to having
      * the VFS grant the requested lock.  Note that this means that other
      * clients may get starved out.
      */
     _debug("try %u", vnode->lock_state);
     if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED) {
         if (type == AFS_LOCK_READ) {
             _debug("instant readlock");
             list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
             fl->fl_u.afs.state = AFS_LOCK_GRANTED;
             goto vnode_is_locked_u;
         }
 
         if (vnode->lock_type == AFS_LOCK_WRITE) {
             _debug("instant writelock");
             list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
             fl->fl_u.afs.state = AFS_LOCK_GRANTED;
             goto vnode_is_locked_u;
         }
     }
 
     if (vnode->lock_state == AFS_VNODE_LOCK_NONE &&
         !(fl->fl_flags & FL_SLEEP)) {
         ret = -EAGAIN;
         if (type == AFS_LOCK_READ) {
             if (vnode->status.lock_count == -1)
                 goto lock_is_contended; /* Write locked */
         } else {
             if (vnode->status.lock_count != 0)
                 goto lock_is_contended; /* Locked */
         }
     }
 
     if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
         goto need_to_wait;
 
 try_to_lock:
     /* We don't have a lock on this vnode and we aren't currently waiting
      * for one either, so ask the server for a lock.
      *
      * Note that we need to be careful if we get interrupted by a signal
      * after dispatching the request as we may still get the lock, even
      * though we don't wait for the reply (it's not too bad a problem - the
      * lock will expire in 5 mins anyway).
      */
     trace_afs_flock_ev(vnode, fl, afs_flock_try_to_lock, 0);
     vnode->lock_key = key_get(key);
     vnode->lock_type = type;
     afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
     spin_unlock(&vnode->lock);
 
     ret = afs_set_lock(vnode, key, type); /* RPC */
 
     spin_lock(&vnode->lock);
     switch (ret) {
     case -EKEYREJECTED:
     case -EKEYEXPIRED:
     case -EKEYREVOKED:
     case -EPERM:
     case -EACCES:
         fl->fl_u.afs.state = ret;
         trace_afs_flock_ev(vnode, fl, afs_flock_fail_perm, ret);
         list_del_init(&fl->fl_u.afs.link);
         afs_next_locker(vnode, ret);
         goto error_unlock;
 
     case -ENOENT:
         fl->fl_u.afs.state = ret;
         trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
         list_del_init(&fl->fl_u.afs.link);
         afs_kill_lockers_enoent(vnode);
         goto error_unlock;
 
     default:
         fl->fl_u.afs.state = ret;
         trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
         list_del_init(&fl->fl_u.afs.link);
         afs_next_locker(vnode, 0);
         goto error_unlock;
 
     case -EWOULDBLOCK:
         /* The server doesn't have a lock-waiting queue, so the client
          * will have to retry.  The server will break the outstanding
          * callbacks on a file when a lock is released.
          */
         ASSERT(list_empty(&vnode->granted_locks));
         ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
         goto lock_is_contended;
 
     case 0:
         afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
         trace_afs_flock_ev(vnode, fl, afs_flock_acquired, type);
         afs_grant_locks(vnode);
         goto vnode_is_locked_u;
     }
 
 vnode_is_locked_u:
     spin_unlock(&vnode->lock);
 vnode_is_locked:
     /* the lock has been granted by the server... */
     ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
 
 skip_server_lock:
     /* ... but the VFS still needs to distribute access on this client. */
     trace_afs_flock_ev(vnode, fl, afs_flock_vfs_locking, 0);
     ret = locks_lock_file_wait(file, fl);
     trace_afs_flock_ev(vnode, fl, afs_flock_vfs_lock, ret);
     if (ret < 0)
         goto vfs_rejected_lock;
 
     /* Again, make sure we've got a callback on this file and, again, make
      * sure that our view of the data version is up to date (we ignore
      * errors incurred here and deal with the consequences elsewhere).
      */
     afs_validate(vnode, key);
     _leave(" = 0");
     return 0;
 
 lock_is_contended:
     if (!(fl->fl_flags & FL_SLEEP)) {
         list_del_init(&fl->fl_u.afs.link);
         afs_next_locker(vnode, 0);
         ret = -EAGAIN;
         goto error_unlock;
     }
 
     afs_set_lock_state(vnode, AFS_VNODE_LOCK_WAITING_FOR_CB);
     trace_afs_flock_ev(vnode, fl, afs_flock_would_block, ret);
     queue_delayed_work(afs_lock_manager, &vnode->lock_work, HZ * 5);
 
 need_to_wait:
     /* We're going to have to wait.  Either this client doesn't have a lock
      * on the server yet and we need to wait for a callback to occur, or
      * the client does have a lock on the server, but it's shared and we
      * need an exclusive lock.
      */
     spin_unlock(&vnode->lock);
 
     trace_afs_flock_ev(vnode, fl, afs_flock_waiting, 0);
     ret = wait_event_interruptible(fl->fl_wait,
                        fl->fl_u.afs.state != AFS_LOCK_PENDING);
     trace_afs_flock_ev(vnode, fl, afs_flock_waited, ret);
 
     if (fl->fl_u.afs.state >= 0 && fl->fl_u.afs.state != AFS_LOCK_GRANTED) {
         spin_lock(&vnode->lock);
 
         switch (fl->fl_u.afs.state) {
         case AFS_LOCK_YOUR_TRY:
             fl->fl_u.afs.state = AFS_LOCK_PENDING;
             goto try_to_lock;
         case AFS_LOCK_PENDING:
             if (ret > 0) {
                 /* We need to retry the lock.  We may not be
                  * notified by the server if it just expired
                  * rather than being released.
                  */
                 ASSERTCMP(vnode->lock_state, ==, AFS_VNODE_LOCK_WAITING_FOR_CB);
                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
                 fl->fl_u.afs.state = AFS_LOCK_PENDING;
                 goto try_to_lock;
             }
             goto error_unlock;
         case AFS_LOCK_GRANTED:
         default:
             break;
         }
 
         spin_unlock(&vnode->lock);
     }
 
     if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
         goto vnode_is_locked;
     ret = fl->fl_u.afs.state;
     goto error;
 
 vfs_rejected_lock:
     /* The VFS rejected the lock we just obtained, so we have to discard
      * what we just got.  We defer this to the lock manager work item to
      * deal with.
      */
     _debug("vfs refused %d", ret);
     if (no_server_lock)
         goto error;
     spin_lock(&vnode->lock);
     list_del_init(&fl->fl_u.afs.link);
     afs_defer_unlock(vnode);
 
 error_unlock:
     spin_unlock(&vnode->lock);
 error:
     _leave(" = %d", ret);
     return ret;
 }
 
 /*
  * unlock on a file on the server
  */
 static int afs_do_unlk(struct file *file, struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
     int ret;
 
     _enter("{%llx:%llu},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
 
     trace_afs_flock_op(vnode, fl, afs_flock_op_unlock);
 
     /* Flush all pending writes before doing anything with locks. */
     vfs_fsync(file, 0);
 
     ret = locks_lock_file_wait(file, fl);
     _leave(" = %d [%u]", ret, vnode->lock_state);
     return ret;
 }
 
 /*
  * return information about a lock we currently hold, if indeed we hold one
  */
 static int afs_do_getlk(struct file *file, struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
     struct key *key = afs_file_key(file);
     int ret, lock_count;
 
     _enter("");
 
     if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
         return -ENOENT;
 
     fl->fl_type = F_UNLCK;
 
     /* check local lock records first */
     posix_test_lock(file, fl);
     if (fl->fl_type == F_UNLCK) {
         /* no local locks; consult the server */
         ret = afs_fetch_status(vnode, key, false, NULL);
         if (ret < 0)
             goto error;
 
         lock_count = READ_ONCE(vnode->status.lock_count);
         if (lock_count != 0) {
             if (lock_count > 0)
                 fl->fl_type = F_RDLCK;
             else
                 fl->fl_type = F_WRLCK;
             fl->fl_start = 0;
             fl->fl_end = OFFSET_MAX;
             fl->fl_pid = 0;
         }
     }
 
     ret = 0;
 error:
     _leave(" = %d [%hd]", ret, fl->fl_type);
     return ret;
 }
 
 /*
  * manage POSIX locks on a file
  */
 int afs_lock(struct file *file, int cmd, struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
     enum afs_flock_operation op;
     int ret;
 
     _enter("{%llx:%llu},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
            vnode->fid.vid, vnode->fid.vnode, cmd,
            fl->fl_type, fl->fl_flags,
            (long long) fl->fl_start, (long long) fl->fl_end);
 
     if (IS_GETLK(cmd))
         return afs_do_getlk(file, fl);
 
     fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
     trace_afs_flock_op(vnode, fl, afs_flock_op_lock);
 
     if (fl->fl_type == F_UNLCK)
         ret = afs_do_unlk(file, fl);
     else
         ret = afs_do_setlk(file, fl);
 
     switch (ret) {
     case 0:     op = afs_flock_op_return_ok; break;
     case -EAGAIN:   op = afs_flock_op_return_eagain; break;
     case -EDEADLK:  op = afs_flock_op_return_edeadlk; break;
     default:    op = afs_flock_op_return_error; break;
     }
     trace_afs_flock_op(vnode, fl, op);
     return ret;
 }
 
 /*
  * manage FLOCK locks on a file
  */
 int afs_flock(struct file *file, int cmd, struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
     enum afs_flock_operation op;
     int ret;
 
     _enter("{%llx:%llu},%d,{t=%x,fl=%x}",
            vnode->fid.vid, vnode->fid.vnode, cmd,
            fl->fl_type, fl->fl_flags);
 
     /*
      * No BSD flocks over NFS allowed.
      * Note: we could try to fake a POSIX lock request here by
      * using ((u32) filp | 0x80000000) or some such as the pid.
      * Not sure whether that would be unique, though, or whether
      * that would break in other places.
      */
     if (!(fl->fl_flags & FL_FLOCK))
         return -ENOLCK;
 
     fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
     trace_afs_flock_op(vnode, fl, afs_flock_op_flock);
 
     /* we're simulating flock() locks using posix locks on the server */
     if (fl->fl_type == F_UNLCK)
         ret = afs_do_unlk(file, fl);
     else
         ret = afs_do_setlk(file, fl);
 
     switch (ret) {
     case 0:     op = afs_flock_op_return_ok; break;
     case -EAGAIN:   op = afs_flock_op_return_eagain; break;
     case -EDEADLK:  op = afs_flock_op_return_edeadlk; break;
     default:    op = afs_flock_op_return_error; break;
     }
     trace_afs_flock_op(vnode, fl, op);
     return ret;
 }
 
 /*
  * the POSIX lock management core VFS code copies the lock record and adds the
  * copy into its own list, so we need to add that copy to the vnode's lock
  * queue in the same place as the original (which will be deleted shortly
  * after)
  */
 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
 
     _enter("");
 
     new->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
 
     spin_lock(&vnode->lock);
     trace_afs_flock_op(vnode, new, afs_flock_op_copy_lock);
     list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
     spin_unlock(&vnode->lock);
 }
 
 /*
  * need to remove this lock from the vnode queue when it's removed from the
  * VFS's list
  */
 static void afs_fl_release_private(struct file_lock *fl)
 {
     struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
 
     _enter("");
 
     spin_lock(&vnode->lock);
 
     trace_afs_flock_op(vnode, fl, afs_flock_op_release_lock);
     list_del_init(&fl->fl_u.afs.link);
     if (list_empty(&vnode->granted_locks))
         afs_defer_unlock(vnode);
 
     _debug("state %u for %p", vnode->lock_state, vnode);
     spin_unlock(&vnode->lock);
 }

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