2 * linux/fs/nfs/delegation.c
4 * Copyright (C) 2004 Trond Myklebust
6 * NFS file delegation management
9 #include <linux/completion.h>
10 #include <linux/kthread.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
16 #include <linux/nfs4.h>
17 #include <linux/nfs_fs.h>
18 #include <linux/nfs_xdr.h>
21 #include "delegation.h"
23 #include "nfs4trace.h"
25 static void nfs_free_delegation(struct nfs_delegation *delegation)
27 if (delegation->cred) {
28 put_rpccred(delegation->cred);
29 delegation->cred = NULL;
31 kfree_rcu(delegation, rcu);
35 * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
36 * @delegation: delegation to process
39 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
41 set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
45 nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
48 if (delegation != NULL && (delegation->type & flags) == flags &&
49 !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
50 !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
56 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
58 struct nfs_delegation *delegation;
61 flags &= FMODE_READ|FMODE_WRITE;
63 delegation = rcu_dereference(NFS_I(inode)->delegation);
64 if (nfs4_is_valid_delegation(delegation, flags)) {
66 nfs_mark_delegation_referenced(delegation);
73 * nfs_have_delegation - check if inode has a delegation, mark it
74 * NFS_DELEGATION_REFERENCED if there is one.
75 * @inode: inode to check
76 * @flags: delegation types to check for
78 * Returns one if inode has the indicated delegation, otherwise zero.
80 int nfs4_have_delegation(struct inode *inode, fmode_t flags)
82 return nfs4_do_check_delegation(inode, flags, true);
86 * nfs4_check_delegation - check if inode has a delegation, do not mark
87 * NFS_DELEGATION_REFERENCED if it has one.
89 int nfs4_check_delegation(struct inode *inode, fmode_t flags)
91 return nfs4_do_check_delegation(inode, flags, false);
94 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
96 struct inode *inode = state->inode;
98 struct file_lock_context *flctx = inode->i_flctx;
99 struct list_head *list;
105 list = &flctx->flc_posix;
106 spin_lock(&flctx->flc_lock);
108 list_for_each_entry(fl, list, fl_list) {
109 if (nfs_file_open_context(fl->fl_file) != ctx)
111 spin_unlock(&flctx->flc_lock);
112 status = nfs4_lock_delegation_recall(fl, state, stateid);
115 spin_lock(&flctx->flc_lock);
117 if (list == &flctx->flc_posix) {
118 list = &flctx->flc_flock;
121 spin_unlock(&flctx->flc_lock);
126 static int nfs_delegation_claim_opens(struct inode *inode,
127 const nfs4_stateid *stateid, fmode_t type)
129 struct nfs_inode *nfsi = NFS_I(inode);
130 struct nfs_open_context *ctx;
131 struct nfs4_state_owner *sp;
132 struct nfs4_state *state;
137 spin_lock(&inode->i_lock);
138 list_for_each_entry(ctx, &nfsi->open_files, list) {
142 if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
144 if (!nfs4_valid_open_stateid(state))
146 if (!nfs4_stateid_match(&state->stateid, stateid))
148 get_nfs_open_context(ctx);
149 spin_unlock(&inode->i_lock);
151 /* Block nfs4_proc_unlck */
152 mutex_lock(&sp->so_delegreturn_mutex);
153 seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
154 err = nfs4_open_delegation_recall(ctx, state, stateid, type);
156 err = nfs_delegation_claim_locks(ctx, state, stateid);
157 if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
159 mutex_unlock(&sp->so_delegreturn_mutex);
160 put_nfs_open_context(ctx);
165 spin_unlock(&inode->i_lock);
170 * nfs_inode_reclaim_delegation - process a delegation reclaim request
171 * @inode: inode to process
172 * @cred: credential to use for request
173 * @res: new delegation state from server
176 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
177 struct nfs_openres *res)
179 struct nfs_delegation *delegation;
180 struct rpc_cred *oldcred = NULL;
183 delegation = rcu_dereference(NFS_I(inode)->delegation);
184 if (delegation != NULL) {
185 spin_lock(&delegation->lock);
186 if (delegation->inode != NULL) {
187 nfs4_stateid_copy(&delegation->stateid, &res->delegation);
188 delegation->type = res->delegation_type;
189 delegation->pagemod_limit = res->pagemod_limit;
190 oldcred = delegation->cred;
191 delegation->cred = get_rpccred(cred);
192 clear_bit(NFS_DELEGATION_NEED_RECLAIM,
194 spin_unlock(&delegation->lock);
196 put_rpccred(oldcred);
197 trace_nfs4_reclaim_delegation(inode, res->delegation_type);
199 /* We appear to have raced with a delegation return. */
200 spin_unlock(&delegation->lock);
202 nfs_inode_set_delegation(inode, cred, res);
209 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
213 if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
214 res = nfs4_proc_delegreturn(inode,
216 &delegation->stateid,
218 nfs_free_delegation(delegation);
222 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
224 struct inode *inode = NULL;
226 spin_lock(&delegation->lock);
227 if (delegation->inode != NULL)
228 inode = igrab(delegation->inode);
229 spin_unlock(&delegation->lock);
233 static struct nfs_delegation *
234 nfs_start_delegation_return_locked(struct nfs_inode *nfsi)
236 struct nfs_delegation *ret = NULL;
237 struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
239 if (delegation == NULL)
241 spin_lock(&delegation->lock);
242 if (!test_and_set_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
244 spin_unlock(&delegation->lock);
249 static struct nfs_delegation *
250 nfs_start_delegation_return(struct nfs_inode *nfsi)
252 struct nfs_delegation *delegation;
255 delegation = nfs_start_delegation_return_locked(nfsi);
261 nfs_abort_delegation_return(struct nfs_delegation *delegation,
262 struct nfs_client *clp)
265 spin_lock(&delegation->lock);
266 clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
267 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
268 spin_unlock(&delegation->lock);
269 set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
272 static struct nfs_delegation *
273 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
274 struct nfs_delegation *delegation,
275 struct nfs_client *clp)
277 struct nfs_delegation *deleg_cur =
278 rcu_dereference_protected(nfsi->delegation,
279 lockdep_is_held(&clp->cl_lock));
281 if (deleg_cur == NULL || delegation != deleg_cur)
284 spin_lock(&delegation->lock);
285 set_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
286 list_del_rcu(&delegation->super_list);
287 delegation->inode = NULL;
288 rcu_assign_pointer(nfsi->delegation, NULL);
289 spin_unlock(&delegation->lock);
293 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
294 struct nfs_delegation *delegation,
295 struct nfs_server *server)
297 struct nfs_client *clp = server->nfs_client;
299 spin_lock(&clp->cl_lock);
300 delegation = nfs_detach_delegation_locked(nfsi, delegation, clp);
301 spin_unlock(&clp->cl_lock);
305 static struct nfs_delegation *
306 nfs_inode_detach_delegation(struct inode *inode)
308 struct nfs_inode *nfsi = NFS_I(inode);
309 struct nfs_server *server = NFS_SERVER(inode);
310 struct nfs_delegation *delegation;
312 delegation = nfs_start_delegation_return(nfsi);
313 if (delegation == NULL)
315 return nfs_detach_delegation(nfsi, delegation, server);
319 nfs_update_inplace_delegation(struct nfs_delegation *delegation,
320 const struct nfs_delegation *update)
322 if (nfs4_stateid_is_newer(&update->stateid, &delegation->stateid)) {
323 delegation->stateid.seqid = update->stateid.seqid;
325 delegation->type = update->type;
330 * nfs_inode_set_delegation - set up a delegation on an inode
331 * @inode: inode to which delegation applies
332 * @cred: cred to use for subsequent delegation processing
333 * @res: new delegation state from server
335 * Returns zero on success, or a negative errno value.
337 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
339 struct nfs_server *server = NFS_SERVER(inode);
340 struct nfs_client *clp = server->nfs_client;
341 struct nfs_inode *nfsi = NFS_I(inode);
342 struct nfs_delegation *delegation, *old_delegation;
343 struct nfs_delegation *freeme = NULL;
346 delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
347 if (delegation == NULL)
349 nfs4_stateid_copy(&delegation->stateid, &res->delegation);
350 delegation->type = res->delegation_type;
351 delegation->pagemod_limit = res->pagemod_limit;
352 delegation->change_attr = inode->i_version;
353 delegation->cred = get_rpccred(cred);
354 delegation->inode = inode;
355 delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
356 spin_lock_init(&delegation->lock);
358 spin_lock(&clp->cl_lock);
359 old_delegation = rcu_dereference_protected(nfsi->delegation,
360 lockdep_is_held(&clp->cl_lock));
361 if (old_delegation != NULL) {
362 /* Is this an update of the existing delegation? */
363 if (nfs4_stateid_match_other(&old_delegation->stateid,
364 &delegation->stateid)) {
365 nfs_update_inplace_delegation(old_delegation,
370 * Deal with broken servers that hand out two
371 * delegations for the same file.
372 * Allow for upgrades to a WRITE delegation, but
375 dfprintk(FILE, "%s: server %s handed out "
376 "a duplicate delegation!\n",
377 __func__, clp->cl_hostname);
378 if (delegation->type == old_delegation->type ||
379 !(delegation->type & FMODE_WRITE)) {
384 if (test_and_set_bit(NFS_DELEGATION_RETURNING,
385 &old_delegation->flags))
387 freeme = nfs_detach_delegation_locked(nfsi,
388 old_delegation, clp);
392 list_add_tail_rcu(&delegation->super_list, &server->delegations);
393 rcu_assign_pointer(nfsi->delegation, delegation);
396 /* Ensure we revalidate the attributes and page cache! */
397 spin_lock(&inode->i_lock);
398 nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
399 spin_unlock(&inode->i_lock);
400 trace_nfs4_set_delegation(inode, res->delegation_type);
403 spin_unlock(&clp->cl_lock);
404 if (delegation != NULL)
405 nfs_free_delegation(delegation);
407 nfs_do_return_delegation(inode, freeme, 0);
412 * Basic procedure for returning a delegation to the server
414 static int nfs_end_delegation_return(struct inode *inode, struct nfs_delegation *delegation, int issync)
416 struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
417 struct nfs_inode *nfsi = NFS_I(inode);
420 if (delegation == NULL)
423 if (test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
425 err = nfs_delegation_claim_opens(inode, &delegation->stateid,
427 if (!issync || err != -EAGAIN)
430 * Guard against state recovery
432 err = nfs4_wait_clnt_recover(clp);
436 nfs_abort_delegation_return(delegation, clp);
439 if (!nfs_detach_delegation(nfsi, delegation, NFS_SERVER(inode)))
442 err = nfs_do_return_delegation(inode, delegation, issync);
447 static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
451 if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
453 if (test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
455 if (test_and_clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags) && !ret) {
458 spin_lock(&delegation->lock);
459 inode = delegation->inode;
460 if (inode && list_empty(&NFS_I(inode)->open_files))
462 spin_unlock(&delegation->lock);
469 * nfs_client_return_marked_delegations - return previously marked delegations
470 * @clp: nfs_client to process
472 * Note that this function is designed to be called by the state
473 * manager thread. For this reason, it cannot flush the dirty data,
474 * since that could deadlock in case of a state recovery error.
476 * Returns zero on success, or a negative errno value.
478 int nfs_client_return_marked_delegations(struct nfs_client *clp)
480 struct nfs_delegation *delegation;
481 struct nfs_server *server;
487 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
488 list_for_each_entry_rcu(delegation, &server->delegations,
490 if (!nfs_delegation_need_return(delegation))
492 if (!nfs_sb_active(server->super))
494 inode = nfs_delegation_grab_inode(delegation);
497 nfs_sb_deactive(server->super);
500 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
503 err = nfs_end_delegation_return(inode, delegation, 0);
505 nfs_sb_deactive(server->super);
508 set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
517 * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
518 * @inode: inode to process
520 * Does not protect against delegation reclaims, therefore really only safe
521 * to be called from nfs4_clear_inode().
523 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
525 struct nfs_delegation *delegation;
527 delegation = nfs_inode_detach_delegation(inode);
528 if (delegation != NULL)
529 nfs_do_return_delegation(inode, delegation, 1);
533 * nfs_inode_return_delegation - synchronously return a delegation
534 * @inode: inode to process
536 * This routine will always flush any dirty data to disk on the
537 * assumption that if we need to return the delegation, then
538 * we should stop caching.
540 * Returns zero on success, or a negative errno value.
542 int nfs4_inode_return_delegation(struct inode *inode)
544 struct nfs_inode *nfsi = NFS_I(inode);
545 struct nfs_delegation *delegation;
549 delegation = nfs_start_delegation_return(nfsi);
550 if (delegation != NULL)
551 err = nfs_end_delegation_return(inode, delegation, 1);
555 static void nfs_mark_return_if_closed_delegation(struct nfs_server *server,
556 struct nfs_delegation *delegation)
558 set_bit(NFS_DELEGATION_RETURN_IF_CLOSED, &delegation->flags);
559 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
562 static void nfs_mark_return_delegation(struct nfs_server *server,
563 struct nfs_delegation *delegation)
565 set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
566 set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
569 static bool nfs_server_mark_return_all_delegations(struct nfs_server *server)
571 struct nfs_delegation *delegation;
574 list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
575 nfs_mark_return_delegation(server, delegation);
581 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
583 struct nfs_server *server;
586 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
587 nfs_server_mark_return_all_delegations(server);
591 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
593 if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
594 nfs4_schedule_state_manager(clp);
598 * nfs_expire_all_delegations
599 * @clp: client to process
602 void nfs_expire_all_delegations(struct nfs_client *clp)
604 nfs_client_mark_return_all_delegations(clp);
605 nfs_delegation_run_state_manager(clp);
609 * nfs_super_return_all_delegations - return delegations for one superblock
613 void nfs_server_return_all_delegations(struct nfs_server *server)
615 struct nfs_client *clp = server->nfs_client;
622 need_wait = nfs_server_mark_return_all_delegations(server);
626 nfs4_schedule_state_manager(clp);
627 nfs4_wait_clnt_recover(clp);
631 static void nfs_mark_return_unused_delegation_types(struct nfs_server *server,
634 struct nfs_delegation *delegation;
636 list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
637 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
639 if (delegation->type & flags)
640 nfs_mark_return_if_closed_delegation(server, delegation);
644 static void nfs_client_mark_return_unused_delegation_types(struct nfs_client *clp,
647 struct nfs_server *server;
650 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
651 nfs_mark_return_unused_delegation_types(server, flags);
655 static void nfs_revoke_delegation(struct inode *inode)
657 struct nfs_delegation *delegation;
659 delegation = rcu_dereference(NFS_I(inode)->delegation);
660 if (delegation != NULL) {
661 set_bit(NFS_DELEGATION_REVOKED, &delegation->flags);
662 nfs_mark_return_delegation(NFS_SERVER(inode), delegation);
667 void nfs_remove_bad_delegation(struct inode *inode)
669 struct nfs_delegation *delegation;
671 nfs_revoke_delegation(inode);
672 delegation = nfs_inode_detach_delegation(inode);
674 nfs_inode_find_state_and_recover(inode, &delegation->stateid);
675 nfs_free_delegation(delegation);
678 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);
681 * nfs_expire_unused_delegation_types
682 * @clp: client to process
683 * @flags: delegation types to expire
686 void nfs_expire_unused_delegation_types(struct nfs_client *clp, fmode_t flags)
688 nfs_client_mark_return_unused_delegation_types(clp, flags);
689 nfs_delegation_run_state_manager(clp);
692 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
694 struct nfs_delegation *delegation;
696 list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
697 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
699 nfs_mark_return_if_closed_delegation(server, delegation);
704 * nfs_expire_unreferenced_delegations - Eliminate unused delegations
705 * @clp: nfs_client to process
708 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
710 struct nfs_server *server;
713 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
714 nfs_mark_return_unreferenced_delegations(server);
717 nfs_delegation_run_state_manager(clp);
721 * nfs_async_inode_return_delegation - asynchronously return a delegation
722 * @inode: inode to process
723 * @stateid: state ID information
725 * Returns zero on success, or a negative errno value.
727 int nfs_async_inode_return_delegation(struct inode *inode,
728 const nfs4_stateid *stateid)
730 struct nfs_server *server = NFS_SERVER(inode);
731 struct nfs_client *clp = server->nfs_client;
732 struct nfs_delegation *delegation;
735 delegation = rcu_dereference(NFS_I(inode)->delegation);
736 if (delegation == NULL)
738 if (stateid != NULL &&
739 !clp->cl_mvops->match_stateid(&delegation->stateid, stateid))
741 nfs_mark_return_delegation(server, delegation);
744 nfs_delegation_run_state_manager(clp);
751 static struct inode *
752 nfs_delegation_find_inode_server(struct nfs_server *server,
753 const struct nfs_fh *fhandle)
755 struct nfs_delegation *delegation;
756 struct inode *res = NULL;
758 list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
759 spin_lock(&delegation->lock);
760 if (delegation->inode != NULL &&
761 nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
762 res = igrab(delegation->inode);
764 spin_unlock(&delegation->lock);
772 * nfs_delegation_find_inode - retrieve the inode associated with a delegation
773 * @clp: client state handle
774 * @fhandle: filehandle from a delegation recall
776 * Returns pointer to inode matching "fhandle," or NULL if a matching inode
779 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
780 const struct nfs_fh *fhandle)
782 struct nfs_server *server;
783 struct inode *res = NULL;
786 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
787 res = nfs_delegation_find_inode_server(server, fhandle);
795 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
797 struct nfs_delegation *delegation;
799 list_for_each_entry_rcu(delegation, &server->delegations, super_list)
800 set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
804 * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
805 * @clp: nfs_client to process
808 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
810 struct nfs_server *server;
813 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
814 nfs_delegation_mark_reclaim_server(server);
819 * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
820 * @clp: nfs_client to process
823 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
825 struct nfs_delegation *delegation;
826 struct nfs_server *server;
831 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
832 list_for_each_entry_rcu(delegation, &server->delegations,
834 if (test_bit(NFS_DELEGATION_RETURNING,
837 if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
838 &delegation->flags) == 0)
840 if (!nfs_sb_active(server->super))
842 inode = nfs_delegation_grab_inode(delegation);
845 nfs_sb_deactive(server->super);
848 delegation = nfs_start_delegation_return_locked(NFS_I(inode));
850 if (delegation != NULL) {
851 delegation = nfs_detach_delegation(NFS_I(inode),
853 if (delegation != NULL)
854 nfs_free_delegation(delegation);
857 nfs_sb_deactive(server->super);
865 * nfs_delegations_present - check for existence of delegations
866 * @clp: client state handle
868 * Returns one if there are any nfs_delegation structures attached
869 * to this nfs_client.
871 int nfs_delegations_present(struct nfs_client *clp)
873 struct nfs_server *server;
877 list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
878 if (!list_empty(&server->delegations)) {
887 * nfs4_copy_delegation_stateid - Copy inode's state ID information
888 * @dst: stateid data structure to fill in
889 * @inode: inode to check
890 * @flags: delegation type requirement
892 * Returns "true" and fills in "dst->data" * if inode had a delegation,
893 * otherwise "false" is returned.
895 bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
898 struct nfs_inode *nfsi = NFS_I(inode);
899 struct nfs_delegation *delegation;
902 flags &= FMODE_READ|FMODE_WRITE;
904 delegation = rcu_dereference(nfsi->delegation);
905 ret = nfs4_is_valid_delegation(delegation, flags);
907 nfs4_stateid_copy(dst, &delegation->stateid);
908 nfs_mark_delegation_referenced(delegation);
915 * nfs4_delegation_flush_on_close - Check if we must flush file on close
916 * @inode: inode to check
918 * This function checks the number of outstanding writes to the file
919 * against the delegation 'space_limit' field to see if
920 * the spec requires us to flush the file on close.
922 bool nfs4_delegation_flush_on_close(const struct inode *inode)
924 struct nfs_inode *nfsi = NFS_I(inode);
925 struct nfs_delegation *delegation;
929 delegation = rcu_dereference(nfsi->delegation);
930 if (delegation == NULL || !(delegation->type & FMODE_WRITE))
932 if (nfsi->nrequests < delegation->pagemod_limit)