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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * linux/fs/nfs/delegation.c
0004  *
0005  * Copyright (C) 2004 Trond Myklebust
0006  *
0007  * NFS file delegation management
0008  *
0009  */
0010 #include <linux/completion.h>
0011 #include <linux/kthread.h>
0012 #include <linux/module.h>
0013 #include <linux/sched.h>
0014 #include <linux/slab.h>
0015 #include <linux/spinlock.h>
0016 #include <linux/iversion.h>
0017 
0018 #include <linux/nfs4.h>
0019 #include <linux/nfs_fs.h>
0020 #include <linux/nfs_xdr.h>
0021 
0022 #include "nfs4_fs.h"
0023 #include "nfs4session.h"
0024 #include "delegation.h"
0025 #include "internal.h"
0026 #include "nfs4trace.h"
0027 
0028 #define NFS_DEFAULT_DELEGATION_WATERMARK (5000U)
0029 
0030 static atomic_long_t nfs_active_delegations;
0031 static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;
0032 
0033 static void __nfs_free_delegation(struct nfs_delegation *delegation)
0034 {
0035     put_cred(delegation->cred);
0036     delegation->cred = NULL;
0037     kfree_rcu(delegation, rcu);
0038 }
0039 
0040 static void nfs_mark_delegation_revoked(struct nfs_delegation *delegation)
0041 {
0042     if (!test_and_set_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
0043         delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
0044         atomic_long_dec(&nfs_active_delegations);
0045         if (!test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
0046             nfs_clear_verifier_delegated(delegation->inode);
0047     }
0048 }
0049 
0050 static struct nfs_delegation *nfs_get_delegation(struct nfs_delegation *delegation)
0051 {
0052     refcount_inc(&delegation->refcount);
0053     return delegation;
0054 }
0055 
0056 static void nfs_put_delegation(struct nfs_delegation *delegation)
0057 {
0058     if (refcount_dec_and_test(&delegation->refcount))
0059         __nfs_free_delegation(delegation);
0060 }
0061 
0062 static void nfs_free_delegation(struct nfs_delegation *delegation)
0063 {
0064     nfs_mark_delegation_revoked(delegation);
0065     nfs_put_delegation(delegation);
0066 }
0067 
0068 /**
0069  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
0070  * @delegation: delegation to process
0071  *
0072  */
0073 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
0074 {
0075     set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
0076 }
0077 
0078 static void nfs_mark_return_delegation(struct nfs_server *server,
0079                        struct nfs_delegation *delegation)
0080 {
0081     set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
0082     set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
0083 }
0084 
0085 static bool
0086 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
0087         fmode_t flags)
0088 {
0089     if (delegation != NULL && (delegation->type & flags) == flags &&
0090         !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
0091         !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
0092         return true;
0093     return false;
0094 }
0095 
0096 struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
0097 {
0098     struct nfs_delegation *delegation;
0099 
0100     delegation = rcu_dereference(NFS_I(inode)->delegation);
0101     if (nfs4_is_valid_delegation(delegation, 0))
0102         return delegation;
0103     return NULL;
0104 }
0105 
0106 static int
0107 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
0108 {
0109     struct nfs_delegation *delegation;
0110     int ret = 0;
0111 
0112     flags &= FMODE_READ|FMODE_WRITE;
0113     rcu_read_lock();
0114     delegation = rcu_dereference(NFS_I(inode)->delegation);
0115     if (nfs4_is_valid_delegation(delegation, flags)) {
0116         if (mark)
0117             nfs_mark_delegation_referenced(delegation);
0118         ret = 1;
0119     }
0120     rcu_read_unlock();
0121     return ret;
0122 }
0123 /**
0124  * nfs4_have_delegation - check if inode has a delegation, mark it
0125  * NFS_DELEGATION_REFERENCED if there is one.
0126  * @inode: inode to check
0127  * @flags: delegation types to check for
0128  *
0129  * Returns one if inode has the indicated delegation, otherwise zero.
0130  */
0131 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
0132 {
0133     return nfs4_do_check_delegation(inode, flags, true);
0134 }
0135 
0136 /*
0137  * nfs4_check_delegation - check if inode has a delegation, do not mark
0138  * NFS_DELEGATION_REFERENCED if it has one.
0139  */
0140 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
0141 {
0142     return nfs4_do_check_delegation(inode, flags, false);
0143 }
0144 
0145 static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
0146 {
0147     struct inode *inode = state->inode;
0148     struct file_lock *fl;
0149     struct file_lock_context *flctx = inode->i_flctx;
0150     struct list_head *list;
0151     int status = 0;
0152 
0153     if (flctx == NULL)
0154         goto out;
0155 
0156     list = &flctx->flc_posix;
0157     spin_lock(&flctx->flc_lock);
0158 restart:
0159     list_for_each_entry(fl, list, fl_list) {
0160         if (nfs_file_open_context(fl->fl_file)->state != state)
0161             continue;
0162         spin_unlock(&flctx->flc_lock);
0163         status = nfs4_lock_delegation_recall(fl, state, stateid);
0164         if (status < 0)
0165             goto out;
0166         spin_lock(&flctx->flc_lock);
0167     }
0168     if (list == &flctx->flc_posix) {
0169         list = &flctx->flc_flock;
0170         goto restart;
0171     }
0172     spin_unlock(&flctx->flc_lock);
0173 out:
0174     return status;
0175 }
0176 
0177 static int nfs_delegation_claim_opens(struct inode *inode,
0178         const nfs4_stateid *stateid, fmode_t type)
0179 {
0180     struct nfs_inode *nfsi = NFS_I(inode);
0181     struct nfs_open_context *ctx;
0182     struct nfs4_state_owner *sp;
0183     struct nfs4_state *state;
0184     unsigned int seq;
0185     int err;
0186 
0187 again:
0188     rcu_read_lock();
0189     list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
0190         state = ctx->state;
0191         if (state == NULL)
0192             continue;
0193         if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
0194             continue;
0195         if (!nfs4_valid_open_stateid(state))
0196             continue;
0197         if (!nfs4_stateid_match(&state->stateid, stateid))
0198             continue;
0199         if (!get_nfs_open_context(ctx))
0200             continue;
0201         rcu_read_unlock();
0202         sp = state->owner;
0203         /* Block nfs4_proc_unlck */
0204         mutex_lock(&sp->so_delegreturn_mutex);
0205         seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
0206         err = nfs4_open_delegation_recall(ctx, state, stateid);
0207         if (!err)
0208             err = nfs_delegation_claim_locks(state, stateid);
0209         if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
0210             err = -EAGAIN;
0211         mutex_unlock(&sp->so_delegreturn_mutex);
0212         put_nfs_open_context(ctx);
0213         if (err != 0)
0214             return err;
0215         goto again;
0216     }
0217     rcu_read_unlock();
0218     return 0;
0219 }
0220 
0221 /**
0222  * nfs_inode_reclaim_delegation - process a delegation reclaim request
0223  * @inode: inode to process
0224  * @cred: credential to use for request
0225  * @type: delegation type
0226  * @stateid: delegation stateid
0227  * @pagemod_limit: write delegation "space_limit"
0228  *
0229  */
0230 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
0231                   fmode_t type,
0232                   const nfs4_stateid *stateid,
0233                   unsigned long pagemod_limit)
0234 {
0235     struct nfs_delegation *delegation;
0236     const struct cred *oldcred = NULL;
0237 
0238     rcu_read_lock();
0239     delegation = rcu_dereference(NFS_I(inode)->delegation);
0240     if (delegation != NULL) {
0241         spin_lock(&delegation->lock);
0242         if (nfs4_is_valid_delegation(delegation, 0)) {
0243             nfs4_stateid_copy(&delegation->stateid, stateid);
0244             delegation->type = type;
0245             delegation->pagemod_limit = pagemod_limit;
0246             oldcred = delegation->cred;
0247             delegation->cred = get_cred(cred);
0248             clear_bit(NFS_DELEGATION_NEED_RECLAIM,
0249                   &delegation->flags);
0250             spin_unlock(&delegation->lock);
0251             rcu_read_unlock();
0252             put_cred(oldcred);
0253             trace_nfs4_reclaim_delegation(inode, type);
0254             return;
0255         }
0256         /* We appear to have raced with a delegation return. */
0257         spin_unlock(&delegation->lock);
0258     }
0259     rcu_read_unlock();
0260     nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
0261 }
0262 
0263 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
0264 {
0265     const struct cred *cred;
0266     int res = 0;
0267 
0268     if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
0269         spin_lock(&delegation->lock);
0270         cred = get_cred(delegation->cred);
0271         spin_unlock(&delegation->lock);
0272         res = nfs4_proc_delegreturn(inode, cred,
0273                 &delegation->stateid,
0274                 issync);
0275         put_cred(cred);
0276     }
0277     return res;
0278 }
0279 
0280 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
0281 {
0282     struct inode *inode = NULL;
0283 
0284     spin_lock(&delegation->lock);
0285     if (delegation->inode != NULL)
0286         inode = igrab(delegation->inode);
0287     if (!inode)
0288         set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
0289     spin_unlock(&delegation->lock);
0290     return inode;
0291 }
0292 
0293 static struct nfs_delegation *
0294 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
0295 {
0296     struct nfs_delegation *ret = NULL;
0297     struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
0298 
0299     if (delegation == NULL)
0300         goto out;
0301     spin_lock(&delegation->lock);
0302     if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
0303         clear_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
0304         /* Refcount matched in nfs_end_delegation_return() */
0305         ret = nfs_get_delegation(delegation);
0306     }
0307     spin_unlock(&delegation->lock);
0308     if (ret)
0309         nfs_clear_verifier_delegated(&nfsi->vfs_inode);
0310 out:
0311     return ret;
0312 }
0313 
0314 static struct nfs_delegation *
0315 nfs_start_delegation_return(struct nfs_inode *nfsi)
0316 {
0317     struct nfs_delegation *delegation;
0318 
0319     rcu_read_lock();
0320     delegation = nfs_start_delegation_return_locked(nfsi);
0321     rcu_read_unlock();
0322     return delegation;
0323 }
0324 
0325 static void nfs_abort_delegation_return(struct nfs_delegation *delegation,
0326                     struct nfs_client *clp, int err)
0327 {
0328 
0329     spin_lock(&delegation->lock);
0330     clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
0331     if (err == -EAGAIN) {
0332         set_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags);
0333         set_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state);
0334     }
0335     spin_unlock(&delegation->lock);
0336 }
0337 
0338 static struct nfs_delegation *
0339 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
0340         struct nfs_delegation *delegation,
0341         struct nfs_client *clp)
0342 {
0343     struct nfs_delegation *deleg_cur =
0344         rcu_dereference_protected(nfsi->delegation,
0345                 lockdep_is_held(&clp->cl_lock));
0346 
0347     if (deleg_cur == NULL || delegation != deleg_cur)
0348         return NULL;
0349 
0350     spin_lock(&delegation->lock);
0351     if (!delegation->inode) {
0352         spin_unlock(&delegation->lock);
0353         return NULL;
0354     }
0355     list_del_rcu(&delegation->super_list);
0356     delegation->inode = NULL;
0357     rcu_assign_pointer(nfsi->delegation, NULL);
0358     spin_unlock(&delegation->lock);
0359     return delegation;
0360 }
0361 
0362 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
0363         struct nfs_delegation *delegation,
0364         struct nfs_server *server)
0365 {
0366     struct nfs_client *clp = server->nfs_client;
0367 
0368     spin_lock(&clp->cl_lock);
0369     delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
0370     spin_unlock(&clp->cl_lock);
0371     return delegation;
0372 }
0373 
0374 static struct nfs_delegation *
0375 nfs_inode_detach_delegation(struct inode *inode)
0376 {
0377     struct nfs_inode *nfsi = NFS_I(inode);
0378     struct nfs_server *server = NFS_SERVER(inode);
0379     struct nfs_delegation *delegation;
0380 
0381     rcu_read_lock();
0382     delegation = rcu_dereference(nfsi->delegation);
0383     if (delegation != NULL)
0384         delegation = nfs_detach_delegation(nfsi, delegation, server);
0385     rcu_read_unlock();
0386     return delegation;
0387 }
0388 
0389 static void
0390 nfs_update_delegation_cred(struct nfs_delegation *delegation,
0391         const struct cred *cred)
0392 {
0393     const struct cred *old;
0394 
0395     if (cred_fscmp(delegation->cred, cred) != 0) {
0396         old = xchg(&delegation->cred, get_cred(cred));
0397         put_cred(old);
0398     }
0399 }
0400 
0401 static void
0402 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
0403         const struct nfs_delegation *update)
0404 {
0405     if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
0406         delegation->stateid.seqid = update->stateid.seqid;
0407         smp_wmb();
0408         delegation->type = update->type;
0409         delegation->pagemod_limit = update->pagemod_limit;
0410         if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
0411             delegation->change_attr = update->change_attr;
0412             nfs_update_delegation_cred(delegation, update->cred);
0413             /* smp_mb__before_atomic() is implicit due to xchg() */
0414             clear_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
0415             atomic_long_inc(&nfs_active_delegations);
0416         }
0417     }
0418 }
0419 
0420 /**
0421  * nfs_inode_set_delegation - set up a delegation on an inode
0422  * @inode: inode to which delegation applies
0423  * @cred: cred to use for subsequent delegation processing
0424  * @type: delegation type
0425  * @stateid: delegation stateid
0426  * @pagemod_limit: write delegation "space_limit"
0427  *
0428  * Returns zero on success, or a negative errno value.
0429  */
0430 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,
0431                   fmode_t type,
0432                   const nfs4_stateid *stateid,
0433                   unsigned long pagemod_limit)
0434 {
0435     struct nfs_server *server = NFS_SERVER(inode);
0436     struct nfs_client *clp = server->nfs_client;
0437     struct nfs_inode *nfsi = NFS_I(inode);
0438     struct nfs_delegation *delegation, *old_delegation;
0439     struct nfs_delegation *freeme = NULL;
0440     int status = 0;
0441 
0442     delegation = kmalloc(sizeof(*delegation), GFP_KERNEL_ACCOUNT);
0443     if (delegation == NULL)
0444         return -ENOMEM;
0445     nfs4_stateid_copy(&delegation->stateid, stateid);
0446     refcount_set(&delegation->refcount, 1);
0447     delegation->type = type;
0448     delegation->pagemod_limit = pagemod_limit;
0449     delegation->change_attr = inode_peek_iversion_raw(inode);
0450     delegation->cred = get_cred(cred);
0451     delegation->inode = inode;
0452     delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
0453     spin_lock_init(&delegation->lock);
0454 
0455     spin_lock(&clp->cl_lock);
0456     old_delegation = rcu_dereference_protected(nfsi->delegation,
0457                     lockdep_is_held(&clp->cl_lock));
0458     if (old_delegation == NULL)
0459         goto add_new;
0460     /* Is this an update of the existing delegation? */
0461     if (nfs4_stateid_match_other(&old_delegation->stateid,
0462                 &delegation->stateid)) {
0463         spin_lock(&old_delegation->lock);
0464         nfs_update_inplace_delegation(old_delegation,
0465                 delegation);
0466         spin_unlock(&old_delegation->lock);
0467         goto out;
0468     }
0469     if (!test_bit(NFS_DELEGATION_REVOKED, &old_delegation->flags)) {
0470         /*
0471          * Deal with broken servers that hand out two
0472          * delegations for the same file.
0473          * Allow for upgrades to a WRITE delegation, but
0474          * nothing else.
0475          */
0476         dfprintk(FILE, "%s: server %s handed out "
0477                 "a duplicate delegation!\n",
0478                 __func__, clp->cl_hostname);
0479         if (delegation->type == old_delegation->type ||
0480             !(delegation->type & FMODE_WRITE)) {
0481             freeme = delegation;
0482             delegation = NULL;
0483             goto out;
0484         }
0485         if (test_and_set_bit(NFS_DELEGATION_RETURNING,
0486                     &old_delegation->flags))
0487             goto out;
0488     }
0489     freeme = nfs_detach_delegation_locked(nfsi, old_delegation, clp);
0490     if (freeme == NULL)
0491         goto out;
0492 add_new:
0493     /*
0494      * If we didn't revalidate the change attribute before setting
0495      * the delegation, then pre-emptively ask for a full attribute
0496      * cache revalidation.
0497      */
0498     spin_lock(&inode->i_lock);
0499     if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_CHANGE)
0500         nfs_set_cache_invalid(inode,
0501             NFS_INO_INVALID_ATIME | NFS_INO_INVALID_CTIME |
0502             NFS_INO_INVALID_MTIME | NFS_INO_INVALID_SIZE |
0503             NFS_INO_INVALID_BLOCKS | NFS_INO_INVALID_NLINK |
0504             NFS_INO_INVALID_OTHER | NFS_INO_INVALID_DATA |
0505             NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL |
0506             NFS_INO_INVALID_XATTR);
0507     spin_unlock(&inode->i_lock);
0508 
0509     list_add_tail_rcu(&delegation->super_list, &server->delegations);
0510     rcu_assign_pointer(nfsi->delegation, delegation);
0511     delegation = NULL;
0512 
0513     atomic_long_inc(&nfs_active_delegations);
0514 
0515     trace_nfs4_set_delegation(inode, type);
0516 out:
0517     spin_unlock(&clp->cl_lock);
0518     if (delegation != NULL)
0519         __nfs_free_delegation(delegation);
0520     if (freeme != NULL) {
0521         nfs_do_return_delegation(inode, freeme, 0);
0522         nfs_free_delegation(freeme);
0523     }
0524     return status;
0525 }
0526 
0527 /*
0528  * Basic procedure for returning a delegation to the server
0529  */
0530 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
0531 {
0532     struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
0533     unsigned int mode = O_WRONLY | O_RDWR;
0534     int err = 0;
0535 
0536     if (delegation == NULL)
0537         return 0;
0538 
0539     if (!issync)
0540         mode |= O_NONBLOCK;
0541     /* Recall of any remaining application leases */
0542     err = break_lease(inode, mode);
0543 
0544     while (err == 0) {
0545         if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
0546             break;
0547         err = nfs_delegation_claim_opens(inode, &delegation->stateid,
0548                 delegation->type);
0549         if (!issync || err != -EAGAIN)
0550             break;
0551         /*
0552          * Guard against state recovery
0553          */
0554         err = nfs4_wait_clnt_recover(clp);
0555     }
0556 
0557     if (err) {
0558         nfs_abort_delegation_return(delegation, clp, err);
0559         goto out;
0560     }
0561 
0562     err = nfs_do_return_delegation(inode, delegation, issync);
0563 out:
0564     /* Refcount matched in nfs_start_delegation_return_locked() */
0565     nfs_put_delegation(delegation);
0566     return err;
0567 }
0568 
0569 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
0570 {
0571     bool ret = false;
0572 
0573     if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
0574         ret = true;
0575     else if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags)) {
0576         struct inode *inode;
0577 
0578         spin_lock(&delegation->lock);
0579         inode = delegation->inode;
0580         if (inode && list_empty(&NFS_I(inode)->open_files))
0581             ret = true;
0582         spin_unlock(&delegation->lock);
0583     }
0584     if (ret)
0585         clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
0586     if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) ||
0587         test_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation->flags) ||
0588         test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
0589         ret = false;
0590 
0591     return ret;
0592 }
0593 
0594 static int nfs_server_return_marked_delegations(struct nfs_server *server,
0595         void __always_unused *data)
0596 {
0597     struct nfs_delegation *delegation;
0598     struct nfs_delegation *prev;
0599     struct inode *inode;
0600     struct inode *place_holder = NULL;
0601     struct nfs_delegation *place_holder_deleg = NULL;
0602     int err = 0;
0603 
0604 restart:
0605     /*
0606      * To avoid quadratic looping we hold a reference
0607      * to an inode place_holder.  Each time we restart, we
0608      * list delegation in the server from the delegations
0609      * of that inode.
0610      * prev is an RCU-protected pointer to a delegation which
0611      * wasn't marked for return and might be a good choice for
0612      * the next place_holder.
0613      */
0614     prev = NULL;
0615     delegation = NULL;
0616     rcu_read_lock();
0617     if (place_holder)
0618         delegation = rcu_dereference(NFS_I(place_holder)->delegation);
0619     if (!delegation || delegation != place_holder_deleg)
0620         delegation = list_entry_rcu(server->delegations.next,
0621                         struct nfs_delegation, super_list);
0622     list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
0623         struct inode *to_put = NULL;
0624 
0625         if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
0626             continue;
0627         if (!nfs_delegation_need_return(delegation)) {
0628             if (nfs4_is_valid_delegation(delegation, 0))
0629                 prev = delegation;
0630             continue;
0631         }
0632 
0633         if (prev) {
0634             struct inode *tmp = nfs_delegation_grab_inode(prev);
0635             if (tmp) {
0636                 to_put = place_holder;
0637                 place_holder = tmp;
0638                 place_holder_deleg = prev;
0639             }
0640         }
0641 
0642         inode = nfs_delegation_grab_inode(delegation);
0643         if (inode == NULL) {
0644             rcu_read_unlock();
0645             iput(to_put);
0646             goto restart;
0647         }
0648         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
0649         rcu_read_unlock();
0650 
0651         iput(to_put);
0652 
0653         err = nfs_end_delegation_return(inode, delegation, 0);
0654         iput(inode);
0655         cond_resched();
0656         if (!err)
0657             goto restart;
0658         set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
0659         goto out;
0660     }
0661     rcu_read_unlock();
0662 out:
0663     iput(place_holder);
0664     return err;
0665 }
0666 
0667 static bool nfs_server_clear_delayed_delegations(struct nfs_server *server)
0668 {
0669     struct nfs_delegation *d;
0670     bool ret = false;
0671 
0672     list_for_each_entry_rcu (d, &server->delegations, super_list) {
0673         if (!test_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags))
0674             continue;
0675         nfs_mark_return_delegation(server, d);
0676         clear_bit(NFS_DELEGATION_RETURN_DELAYED, &d->flags);
0677         ret = true;
0678     }
0679     return ret;
0680 }
0681 
0682 static bool nfs_client_clear_delayed_delegations(struct nfs_client *clp)
0683 {
0684     struct nfs_server *server;
0685     bool ret = false;
0686 
0687     if (!test_and_clear_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp->cl_state))
0688         goto out;
0689     rcu_read_lock();
0690     list_for_each_entry_rcu (server, &clp->cl_superblocks, client_link) {
0691         if (nfs_server_clear_delayed_delegations(server))
0692             ret = true;
0693     }
0694     rcu_read_unlock();
0695 out:
0696     return ret;
0697 }
0698 
0699 /**
0700  * nfs_client_return_marked_delegations - return previously marked delegations
0701  * @clp: nfs_client to process
0702  *
0703  * Note that this function is designed to be called by the state
0704  * manager thread. For this reason, it cannot flush the dirty data,
0705  * since that could deadlock in case of a state recovery error.
0706  *
0707  * Returns zero on success, or a negative errno value.
0708  */
0709 int nfs_client_return_marked_delegations(struct nfs_client *clp)
0710 {
0711     int err = nfs_client_for_each_server(
0712         clp, nfs_server_return_marked_delegations, NULL);
0713     if (err)
0714         return err;
0715     /* If a return was delayed, sleep to prevent hard looping */
0716     if (nfs_client_clear_delayed_delegations(clp))
0717         ssleep(1);
0718     return 0;
0719 }
0720 
0721 /**
0722  * nfs_inode_evict_delegation - return delegation, don't reclaim opens
0723  * @inode: inode to process
0724  *
0725  * Does not protect against delegation reclaims, therefore really only safe
0726  * to be called from nfs4_clear_inode(). Guaranteed to always free
0727  * the delegation structure.
0728  */
0729 void nfs_inode_evict_delegation(struct inode *inode)
0730 {
0731     struct nfs_delegation *delegation;
0732 
0733     delegation = nfs_inode_detach_delegation(inode);
0734     if (delegation != NULL) {
0735         set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
0736         set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
0737         nfs_do_return_delegation(inode, delegation, 1);
0738         nfs_free_delegation(delegation);
0739     }
0740 }
0741 
0742 /**
0743  * nfs4_inode_return_delegation - synchronously return a delegation
0744  * @inode: inode to process
0745  *
0746  * This routine will always flush any dirty data to disk on the
0747  * assumption that if we need to return the delegation, then
0748  * we should stop caching.
0749  *
0750  * Returns zero on success, or a negative errno value.
0751  */
0752 int nfs4_inode_return_delegation(struct inode *inode)
0753 {
0754     struct nfs_inode *nfsi = NFS_I(inode);
0755     struct nfs_delegation *delegation;
0756 
0757     delegation = nfs_start_delegation_return(nfsi);
0758     if (delegation != NULL) {
0759         /* Synchronous recall of any application leases */
0760         break_lease(inode, O_WRONLY | O_RDWR);
0761         if (S_ISREG(inode->i_mode))
0762             nfs_wb_all(inode);
0763         return nfs_end_delegation_return(inode, delegation, 1);
0764     }
0765     return 0;
0766 }
0767 
0768 /**
0769  * nfs4_inode_return_delegation_on_close - asynchronously return a delegation
0770  * @inode: inode to process
0771  *
0772  * This routine is called on file close in order to determine if the
0773  * inode delegation needs to be returned immediately.
0774  */
0775 void nfs4_inode_return_delegation_on_close(struct inode *inode)
0776 {
0777     struct nfs_delegation *delegation;
0778     struct nfs_delegation *ret = NULL;
0779 
0780     if (!inode)
0781         return;
0782     rcu_read_lock();
0783     delegation = nfs4_get_valid_delegation(inode);
0784     if (!delegation)
0785         goto out;
0786     if (test_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) ||
0787         atomic_long_read(&nfs_active_delegations) >= nfs_delegation_watermark) {
0788         spin_lock(&delegation->lock);
0789         if (delegation->inode &&
0790             list_empty(&NFS_I(inode)->open_files) &&
0791             !test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
0792             clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
0793             /* Refcount matched in nfs_end_delegation_return() */
0794             ret = nfs_get_delegation(delegation);
0795         }
0796         spin_unlock(&delegation->lock);
0797         if (ret)
0798             nfs_clear_verifier_delegated(inode);
0799     }
0800 out:
0801     rcu_read_unlock();
0802     nfs_end_delegation_return(inode, ret, 0);
0803 }
0804 
0805 /**
0806  * nfs4_inode_make_writeable
0807  * @inode: pointer to inode
0808  *
0809  * Make the inode writeable by returning the delegation if necessary
0810  *
0811  * Returns zero on success, or a negative errno value.
0812  */
0813 int nfs4_inode_make_writeable(struct inode *inode)
0814 {
0815     struct nfs_delegation *delegation;
0816 
0817     rcu_read_lock();
0818     delegation = nfs4_get_valid_delegation(inode);
0819     if (delegation == NULL ||
0820         (nfs4_has_session(NFS_SERVER(inode)->nfs_client) &&
0821          (delegation->type & FMODE_WRITE))) {
0822         rcu_read_unlock();
0823         return 0;
0824     }
0825     rcu_read_unlock();
0826     return nfs4_inode_return_delegation(inode);
0827 }
0828 
0829 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
0830         struct nfs_delegation *delegation)
0831 {
0832     set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
0833     set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
0834 }
0835 
0836 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
0837 {
0838     struct nfs_delegation *delegation;
0839     bool ret = false;
0840 
0841     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
0842         nfs_mark_return_delegation(server, delegation);
0843         ret = true;
0844     }
0845     return ret;
0846 }
0847 
0848 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
0849 {
0850     struct nfs_server *server;
0851 
0852     rcu_read_lock();
0853     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
0854         nfs_server_mark_return_all_delegations(server);
0855     rcu_read_unlock();
0856 }
0857 
0858 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
0859 {
0860     if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
0861         nfs4_schedule_state_manager(clp);
0862 }
0863 
0864 /**
0865  * nfs_expire_all_delegations
0866  * @clp: client to process
0867  *
0868  */
0869 void nfs_expire_all_delegations(struct nfs_client *clp)
0870 {
0871     nfs_client_mark_return_all_delegations(clp);
0872     nfs_delegation_run_state_manager(clp);
0873 }
0874 
0875 /**
0876  * nfs_server_return_all_delegations - return delegations for one superblock
0877  * @server: pointer to nfs_server to process
0878  *
0879  */
0880 void nfs_server_return_all_delegations(struct nfs_server *server)
0881 {
0882     struct nfs_client *clp = server->nfs_client;
0883     bool need_wait;
0884 
0885     if (clp == NULL)
0886         return;
0887 
0888     rcu_read_lock();
0889     need_wait = nfs_server_mark_return_all_delegations(server);
0890     rcu_read_unlock();
0891 
0892     if (need_wait) {
0893         nfs4_schedule_state_manager(clp);
0894         nfs4_wait_clnt_recover(clp);
0895     }
0896 }
0897 
0898 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
0899                          fmode_t flags)
0900 {
0901     struct nfs_delegation *delegation;
0902 
0903     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
0904         if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
0905             continue;
0906         if (delegation->type & flags)
0907             nfs_mark_return_if_closed_delegation(server, delegation);
0908     }
0909 }
0910 
0911 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
0912                             fmode_t flags)
0913 {
0914     struct nfs_server *server;
0915 
0916     rcu_read_lock();
0917     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
0918         nfs_mark_return_unused_delegation_types(server, flags);
0919     rcu_read_unlock();
0920 }
0921 
0922 static void nfs_revoke_delegation(struct inode *inode,
0923         const nfs4_stateid *stateid)
0924 {
0925     struct nfs_delegation *delegation;
0926     nfs4_stateid tmp;
0927     bool ret = false;
0928 
0929     rcu_read_lock();
0930     delegation = rcu_dereference(NFS_I(inode)->delegation);
0931     if (delegation == NULL)
0932         goto out;
0933     if (stateid == NULL) {
0934         nfs4_stateid_copy(&tmp, &delegation->stateid);
0935         stateid = &tmp;
0936     } else {
0937         if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
0938             goto out;
0939         spin_lock(&delegation->lock);
0940         if (stateid->seqid) {
0941             if (nfs4_stateid_is_newer(&delegation->stateid, stateid)) {
0942                 spin_unlock(&delegation->lock);
0943                 goto out;
0944             }
0945             delegation->stateid.seqid = stateid->seqid;
0946         }
0947         spin_unlock(&delegation->lock);
0948     }
0949     nfs_mark_delegation_revoked(delegation);
0950     ret = true;
0951 out:
0952     rcu_read_unlock();
0953     if (ret)
0954         nfs_inode_find_state_and_recover(inode, stateid);
0955 }
0956 
0957 void nfs_remove_bad_delegation(struct inode *inode,
0958         const nfs4_stateid *stateid)
0959 {
0960     nfs_revoke_delegation(inode, stateid);
0961 }
0962 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
0963 
0964 void nfs_delegation_mark_returned(struct inode *inode,
0965         const nfs4_stateid *stateid)
0966 {
0967     struct nfs_delegation *delegation;
0968 
0969     if (!inode)
0970         return;
0971 
0972     rcu_read_lock();
0973     delegation = rcu_dereference(NFS_I(inode)->delegation);
0974     if (!delegation)
0975         goto out_rcu_unlock;
0976 
0977     spin_lock(&delegation->lock);
0978     if (!nfs4_stateid_match_other(stateid, &delegation->stateid))
0979         goto out_spin_unlock;
0980     if (stateid->seqid) {
0981         /* If delegation->stateid is newer, dont mark as returned */
0982         if (nfs4_stateid_is_newer(&delegation->stateid, stateid))
0983             goto out_clear_returning;
0984         if (delegation->stateid.seqid != stateid->seqid)
0985             delegation->stateid.seqid = stateid->seqid;
0986     }
0987 
0988     nfs_mark_delegation_revoked(delegation);
0989 
0990 out_clear_returning:
0991     clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
0992 out_spin_unlock:
0993     spin_unlock(&delegation->lock);
0994 out_rcu_unlock:
0995     rcu_read_unlock();
0996 
0997     nfs_inode_find_state_and_recover(inode, stateid);
0998 }
0999 
1000 /**
1001  * nfs_expire_unused_delegation_types
1002  * @clp: client to process
1003  * @flags: delegation types to expire
1004  *
1005  */
1006 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
1007 {
1008     nfs_client_mark_return_unused_delegation_types(clp, flags);
1009     nfs_delegation_run_state_manager(clp);
1010 }
1011 
1012 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
1013 {
1014     struct nfs_delegation *delegation;
1015 
1016     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1017         if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
1018             continue;
1019         nfs_mark_return_if_closed_delegation(server, delegation);
1020     }
1021 }
1022 
1023 /**
1024  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
1025  * @clp: nfs_client to process
1026  *
1027  */
1028 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
1029 {
1030     struct nfs_server *server;
1031 
1032     rcu_read_lock();
1033     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1034         nfs_mark_return_unreferenced_delegations(server);
1035     rcu_read_unlock();
1036 
1037     nfs_delegation_run_state_manager(clp);
1038 }
1039 
1040 /**
1041  * nfs_async_inode_return_delegation - asynchronously return a delegation
1042  * @inode: inode to process
1043  * @stateid: state ID information
1044  *
1045  * Returns zero on success, or a negative errno value.
1046  */
1047 int nfs_async_inode_return_delegation(struct inode *inode,
1048                       const nfs4_stateid *stateid)
1049 {
1050     struct nfs_server *server = NFS_SERVER(inode);
1051     struct nfs_client *clp = server->nfs_client;
1052     struct nfs_delegation *delegation;
1053 
1054     rcu_read_lock();
1055     delegation = nfs4_get_valid_delegation(inode);
1056     if (delegation == NULL)
1057         goto out_enoent;
1058     if (stateid != NULL &&
1059         !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
1060         goto out_enoent;
1061     nfs_mark_return_delegation(server, delegation);
1062     rcu_read_unlock();
1063 
1064     /* If there are any application leases or delegations, recall them */
1065     break_lease(inode, O_WRONLY | O_RDWR | O_NONBLOCK);
1066 
1067     nfs_delegation_run_state_manager(clp);
1068     return 0;
1069 out_enoent:
1070     rcu_read_unlock();
1071     return -ENOENT;
1072 }
1073 
1074 static struct inode *
1075 nfs_delegation_find_inode_server(struct nfs_server *server,
1076                  const struct nfs_fh *fhandle)
1077 {
1078     struct nfs_delegation *delegation;
1079     struct super_block *freeme = NULL;
1080     struct inode *res = NULL;
1081 
1082     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1083         spin_lock(&delegation->lock);
1084         if (delegation->inode != NULL &&
1085             !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
1086             nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
1087             if (nfs_sb_active(server->super)) {
1088                 freeme = server->super;
1089                 res = igrab(delegation->inode);
1090             }
1091             spin_unlock(&delegation->lock);
1092             if (res != NULL)
1093                 return res;
1094             if (freeme) {
1095                 rcu_read_unlock();
1096                 nfs_sb_deactive(freeme);
1097                 rcu_read_lock();
1098             }
1099             return ERR_PTR(-EAGAIN);
1100         }
1101         spin_unlock(&delegation->lock);
1102     }
1103     return ERR_PTR(-ENOENT);
1104 }
1105 
1106 /**
1107  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
1108  * @clp: client state handle
1109  * @fhandle: filehandle from a delegation recall
1110  *
1111  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
1112  * cannot be found.
1113  */
1114 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
1115                     const struct nfs_fh *fhandle)
1116 {
1117     struct nfs_server *server;
1118     struct inode *res;
1119 
1120     rcu_read_lock();
1121     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
1122         res = nfs_delegation_find_inode_server(server, fhandle);
1123         if (res != ERR_PTR(-ENOENT)) {
1124             rcu_read_unlock();
1125             return res;
1126         }
1127     }
1128     rcu_read_unlock();
1129     return ERR_PTR(-ENOENT);
1130 }
1131 
1132 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
1133 {
1134     struct nfs_delegation *delegation;
1135 
1136     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1137         /*
1138          * If the delegation may have been admin revoked, then we
1139          * cannot reclaim it.
1140          */
1141         if (test_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags))
1142             continue;
1143         set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1144     }
1145 }
1146 
1147 /**
1148  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
1149  * @clp: nfs_client to process
1150  *
1151  */
1152 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
1153 {
1154     struct nfs_server *server;
1155 
1156     rcu_read_lock();
1157     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1158         nfs_delegation_mark_reclaim_server(server);
1159     rcu_read_unlock();
1160 }
1161 
1162 static int nfs_server_reap_unclaimed_delegations(struct nfs_server *server,
1163         void __always_unused *data)
1164 {
1165     struct nfs_delegation *delegation;
1166     struct inode *inode;
1167 restart:
1168     rcu_read_lock();
1169 restart_locked:
1170     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1171         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1172                     &delegation->flags) ||
1173             test_bit(NFS_DELEGATION_RETURNING,
1174                     &delegation->flags) ||
1175             test_bit(NFS_DELEGATION_NEED_RECLAIM,
1176                     &delegation->flags) == 0)
1177             continue;
1178         inode = nfs_delegation_grab_inode(delegation);
1179         if (inode == NULL)
1180             goto restart_locked;
1181         delegation = nfs_start_delegation_return_locked(NFS_I(inode));
1182         rcu_read_unlock();
1183         if (delegation != NULL) {
1184             if (nfs_detach_delegation(NFS_I(inode), delegation,
1185                         server) != NULL)
1186                 nfs_free_delegation(delegation);
1187             /* Match nfs_start_delegation_return_locked */
1188             nfs_put_delegation(delegation);
1189         }
1190         iput(inode);
1191         cond_resched();
1192         goto restart;
1193     }
1194     rcu_read_unlock();
1195     return 0;
1196 }
1197 
1198 /**
1199  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
1200  * @clp: nfs_client to process
1201  *
1202  */
1203 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
1204 {
1205     nfs_client_for_each_server(clp, nfs_server_reap_unclaimed_delegations,
1206             NULL);
1207 }
1208 
1209 static inline bool nfs4_server_rebooted(const struct nfs_client *clp)
1210 {
1211     return (clp->cl_state & (BIT(NFS4CLNT_CHECK_LEASE) |
1212                 BIT(NFS4CLNT_LEASE_EXPIRED) |
1213                 BIT(NFS4CLNT_SESSION_RESET))) != 0;
1214 }
1215 
1216 static void nfs_mark_test_expired_delegation(struct nfs_server *server,
1217         struct nfs_delegation *delegation)
1218 {
1219     if (delegation->stateid.type == NFS4_INVALID_STATEID_TYPE)
1220         return;
1221     clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
1222     set_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1223     set_bit(NFS4CLNT_DELEGATION_EXPIRED, &server->nfs_client->cl_state);
1224 }
1225 
1226 static void nfs_inode_mark_test_expired_delegation(struct nfs_server *server,
1227         struct inode *inode)
1228 {
1229     struct nfs_delegation *delegation;
1230 
1231     rcu_read_lock();
1232     delegation = rcu_dereference(NFS_I(inode)->delegation);
1233     if (delegation)
1234         nfs_mark_test_expired_delegation(server, delegation);
1235     rcu_read_unlock();
1236 
1237 }
1238 
1239 static void nfs_delegation_mark_test_expired_server(struct nfs_server *server)
1240 {
1241     struct nfs_delegation *delegation;
1242 
1243     list_for_each_entry_rcu(delegation, &server->delegations, super_list)
1244         nfs_mark_test_expired_delegation(server, delegation);
1245 }
1246 
1247 /**
1248  * nfs_mark_test_expired_all_delegations - mark all delegations for testing
1249  * @clp: nfs_client to process
1250  *
1251  * Iterates through all the delegations associated with this server and
1252  * marks them as needing to be checked for validity.
1253  */
1254 void nfs_mark_test_expired_all_delegations(struct nfs_client *clp)
1255 {
1256     struct nfs_server *server;
1257 
1258     rcu_read_lock();
1259     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1260         nfs_delegation_mark_test_expired_server(server);
1261     rcu_read_unlock();
1262 }
1263 
1264 /**
1265  * nfs_test_expired_all_delegations - test all delegations for a client
1266  * @clp: nfs_client to process
1267  *
1268  * Helper for handling "recallable state revoked" status from server.
1269  */
1270 void nfs_test_expired_all_delegations(struct nfs_client *clp)
1271 {
1272     nfs_mark_test_expired_all_delegations(clp);
1273     nfs4_schedule_state_manager(clp);
1274 }
1275 
1276 static void
1277 nfs_delegation_test_free_expired(struct inode *inode,
1278         nfs4_stateid *stateid,
1279         const struct cred *cred)
1280 {
1281     struct nfs_server *server = NFS_SERVER(inode);
1282     const struct nfs4_minor_version_ops *ops = server->nfs_client->cl_mvops;
1283     int status;
1284 
1285     if (!cred)
1286         return;
1287     status = ops->test_and_free_expired(server, stateid, cred);
1288     if (status == -NFS4ERR_EXPIRED || status == -NFS4ERR_BAD_STATEID)
1289         nfs_remove_bad_delegation(inode, stateid);
1290 }
1291 
1292 static int nfs_server_reap_expired_delegations(struct nfs_server *server,
1293         void __always_unused *data)
1294 {
1295     struct nfs_delegation *delegation;
1296     struct inode *inode;
1297     const struct cred *cred;
1298     nfs4_stateid stateid;
1299 restart:
1300     rcu_read_lock();
1301 restart_locked:
1302     list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
1303         if (test_bit(NFS_DELEGATION_INODE_FREEING,
1304                     &delegation->flags) ||
1305             test_bit(NFS_DELEGATION_RETURNING,
1306                     &delegation->flags) ||
1307             test_bit(NFS_DELEGATION_TEST_EXPIRED,
1308                     &delegation->flags) == 0)
1309             continue;
1310         inode = nfs_delegation_grab_inode(delegation);
1311         if (inode == NULL)
1312             goto restart_locked;
1313         spin_lock(&delegation->lock);
1314         cred = get_cred_rcu(delegation->cred);
1315         nfs4_stateid_copy(&stateid, &delegation->stateid);
1316         spin_unlock(&delegation->lock);
1317         clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
1318         rcu_read_unlock();
1319         nfs_delegation_test_free_expired(inode, &stateid, cred);
1320         put_cred(cred);
1321         if (!nfs4_server_rebooted(server->nfs_client)) {
1322             iput(inode);
1323             cond_resched();
1324             goto restart;
1325         }
1326         nfs_inode_mark_test_expired_delegation(server,inode);
1327         iput(inode);
1328         return -EAGAIN;
1329     }
1330     rcu_read_unlock();
1331     return 0;
1332 }
1333 
1334 /**
1335  * nfs_reap_expired_delegations - reap expired delegations
1336  * @clp: nfs_client to process
1337  *
1338  * Iterates through all the delegations associated with this server and
1339  * checks if they have may have been revoked. This function is usually
1340  * expected to be called in cases where the server may have lost its
1341  * lease.
1342  */
1343 void nfs_reap_expired_delegations(struct nfs_client *clp)
1344 {
1345     nfs_client_for_each_server(clp, nfs_server_reap_expired_delegations,
1346             NULL);
1347 }
1348 
1349 void nfs_inode_find_delegation_state_and_recover(struct inode *inode,
1350         const nfs4_stateid *stateid)
1351 {
1352     struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
1353     struct nfs_delegation *delegation;
1354     bool found = false;
1355 
1356     rcu_read_lock();
1357     delegation = rcu_dereference(NFS_I(inode)->delegation);
1358     if (delegation &&
1359         nfs4_stateid_match_or_older(&delegation->stateid, stateid) &&
1360         !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1361         nfs_mark_test_expired_delegation(NFS_SERVER(inode), delegation);
1362         found = true;
1363     }
1364     rcu_read_unlock();
1365     if (found)
1366         nfs4_schedule_state_manager(clp);
1367 }
1368 
1369 /**
1370  * nfs_delegations_present - check for existence of delegations
1371  * @clp: client state handle
1372  *
1373  * Returns one if there are any nfs_delegation structures attached
1374  * to this nfs_client.
1375  */
1376 int nfs_delegations_present(struct nfs_client *clp)
1377 {
1378     struct nfs_server *server;
1379     int ret = 0;
1380 
1381     rcu_read_lock();
1382     list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
1383         if (!list_empty(&server->delegations)) {
1384             ret = 1;
1385             break;
1386         }
1387     rcu_read_unlock();
1388     return ret;
1389 }
1390 
1391 /**
1392  * nfs4_refresh_delegation_stateid - Update delegation stateid seqid
1393  * @dst: stateid to refresh
1394  * @inode: inode to check
1395  *
1396  * Returns "true" and updates "dst->seqid" * if inode had a delegation
1397  * that matches our delegation stateid. Otherwise "false" is returned.
1398  */
1399 bool nfs4_refresh_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
1400 {
1401     struct nfs_delegation *delegation;
1402     bool ret = false;
1403     if (!inode)
1404         goto out;
1405 
1406     rcu_read_lock();
1407     delegation = rcu_dereference(NFS_I(inode)->delegation);
1408     if (delegation != NULL &&
1409         nfs4_stateid_match_other(dst, &delegation->stateid) &&
1410         nfs4_stateid_is_newer(&delegation->stateid, dst) &&
1411         !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
1412         dst->seqid = delegation->stateid.seqid;
1413         ret = true;
1414     }
1415     rcu_read_unlock();
1416 out:
1417     return ret;
1418 }
1419 
1420 /**
1421  * nfs4_copy_delegation_stateid - Copy inode's state ID information
1422  * @inode: inode to check
1423  * @flags: delegation type requirement
1424  * @dst: stateid data structure to fill in
1425  * @cred: optional argument to retrieve credential
1426  *
1427  * Returns "true" and fills in "dst->data" * if inode had a delegation,
1428  * otherwise "false" is returned.
1429  */
1430 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
1431         nfs4_stateid *dst, const struct cred **cred)
1432 {
1433     struct nfs_inode *nfsi = NFS_I(inode);
1434     struct nfs_delegation *delegation;
1435     bool ret = false;
1436 
1437     flags &= FMODE_READ|FMODE_WRITE;
1438     rcu_read_lock();
1439     delegation = rcu_dereference(nfsi->delegation);
1440     if (!delegation)
1441         goto out;
1442     spin_lock(&delegation->lock);
1443     ret = nfs4_is_valid_delegation(delegation, flags);
1444     if (ret) {
1445         nfs4_stateid_copy(dst, &delegation->stateid);
1446         nfs_mark_delegation_referenced(delegation);
1447         if (cred)
1448             *cred = get_cred(delegation->cred);
1449     }
1450     spin_unlock(&delegation->lock);
1451 out:
1452     rcu_read_unlock();
1453     return ret;
1454 }
1455 
1456 /**
1457  * nfs4_delegation_flush_on_close - Check if we must flush file on close
1458  * @inode: inode to check
1459  *
1460  * This function checks the number of outstanding writes to the file
1461  * against the delegation 'space_limit' field to see if
1462  * the spec requires us to flush the file on close.
1463  */
1464 bool nfs4_delegation_flush_on_close(const struct inode *inode)
1465 {
1466     struct nfs_inode *nfsi = NFS_I(inode);
1467     struct nfs_delegation *delegation;
1468     bool ret = true;
1469 
1470     rcu_read_lock();
1471     delegation = rcu_dereference(nfsi->delegation);
1472     if (delegation == NULL || !(delegation->type & FMODE_WRITE))
1473         goto out;
1474     if (atomic_long_read(&nfsi->nrequests) < delegation->pagemod_limit)
1475         ret = false;
1476 out:
1477     rcu_read_unlock();
1478     return ret;
1479 }
1480 
1481 module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);
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