1 // SPDX-License-Identifier: GPL-2.0-only
5 * We implement four types of file locks: BSD locks, posix locks, open
6 * file description locks, and leases. For details about BSD locks,
7 * see the flock(2) man page; for details about the other three, see
11 * Locking conflicts and dependencies:
12 * If multiple threads attempt to lock the same byte (or flock the same file)
13 * only one can be granted the lock, and other must wait their turn.
14 * The first lock has been "applied" or "granted", the others are "waiting"
15 * and are "blocked" by the "applied" lock..
17 * Waiting and applied locks are all kept in trees whose properties are:
19 * - the root of a tree may be an applied or waiting lock.
20 * - every other node in the tree is a waiting lock that
21 * conflicts with every ancestor of that node.
23 * Every such tree begins life as a waiting singleton which obviously
24 * satisfies the above properties.
26 * The only ways we modify trees preserve these properties:
28 * 1. We may add a new leaf node, but only after first verifying that it
29 * conflicts with all of its ancestors.
30 * 2. We may remove the root of a tree, creating a new singleton
31 * tree from the root and N new trees rooted in the immediate
33 * 3. If the root of a tree is not currently an applied lock, we may
34 * apply it (if possible).
35 * 4. We may upgrade the root of the tree (either extend its range,
36 * or upgrade its entire range from read to write).
38 * When an applied lock is modified in a way that reduces or downgrades any
39 * part of its range, we remove all its children (2 above). This particularly
40 * happens when a lock is unlocked.
42 * For each of those child trees we "wake up" the thread which is
43 * waiting for the lock so it can continue handling as follows: if the
44 * root of the tree applies, we do so (3). If it doesn't, it must
45 * conflict with some applied lock. We remove (wake up) all of its children
46 * (2), and add it is a new leaf to the tree rooted in the applied
47 * lock (1). We then repeat the process recursively with those
52 #include <linux/capability.h>
53 #include <linux/file.h>
54 #include <linux/fdtable.h>
55 #include <linux/filelock.h>
57 #include <linux/init.h>
58 #include <linux/security.h>
59 #include <linux/slab.h>
60 #include <linux/syscalls.h>
61 #include <linux/time.h>
62 #include <linux/rcupdate.h>
63 #include <linux/pid_namespace.h>
64 #include <linux/hashtable.h>
65 #include <linux/percpu.h>
66 #include <linux/sysctl.h>
68 #define CREATE_TRACE_POINTS
69 #include <trace/events/filelock.h>
71 #include <linux/uaccess.h>
73 #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
74 #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
75 #define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
76 #define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
77 #define IS_REMOTELCK(fl) (fl->fl_pid <= 0)
79 static bool lease_breaking(struct file_lock *fl)
81 return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
84 static int target_leasetype(struct file_lock *fl)
86 if (fl->fl_flags & FL_UNLOCK_PENDING)
88 if (fl->fl_flags & FL_DOWNGRADE_PENDING)
93 static int leases_enable = 1;
94 static int lease_break_time = 45;
97 static struct ctl_table locks_sysctls[] = {
99 .procname = "leases-enable",
100 .data = &leases_enable,
101 .maxlen = sizeof(int),
103 .proc_handler = proc_dointvec,
107 .procname = "lease-break-time",
108 .data = &lease_break_time,
109 .maxlen = sizeof(int),
111 .proc_handler = proc_dointvec,
113 #endif /* CONFIG_MMU */
117 static int __init init_fs_locks_sysctls(void)
119 register_sysctl_init("fs", locks_sysctls);
122 early_initcall(init_fs_locks_sysctls);
123 #endif /* CONFIG_SYSCTL */
126 * The global file_lock_list is only used for displaying /proc/locks, so we
127 * keep a list on each CPU, with each list protected by its own spinlock.
128 * Global serialization is done using file_rwsem.
130 * Note that alterations to the list also require that the relevant flc_lock is
133 struct file_lock_list_struct {
135 struct hlist_head hlist;
137 static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
138 DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
142 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
143 * It is protected by blocked_lock_lock.
145 * We hash locks by lockowner in order to optimize searching for the lock a
146 * particular lockowner is waiting on.
148 * FIXME: make this value scale via some heuristic? We generally will want more
149 * buckets when we have more lockowners holding locks, but that's a little
150 * difficult to determine without knowing what the workload will look like.
152 #define BLOCKED_HASH_BITS 7
153 static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
156 * This lock protects the blocked_hash. Generally, if you're accessing it, you
157 * want to be holding this lock.
159 * In addition, it also protects the fl->fl_blocked_requests list, and the
160 * fl->fl_blocker pointer for file_lock structures that are acting as lock
161 * requests (in contrast to those that are acting as records of acquired locks).
163 * Note that when we acquire this lock in order to change the above fields,
164 * we often hold the flc_lock as well. In certain cases, when reading the fields
165 * protected by this lock, we can skip acquiring it iff we already hold the
168 static DEFINE_SPINLOCK(blocked_lock_lock);
170 static struct kmem_cache *flctx_cache __ro_after_init;
171 static struct kmem_cache *filelock_cache __ro_after_init;
173 static struct file_lock_context *
174 locks_get_lock_context(struct inode *inode, int type)
176 struct file_lock_context *ctx;
178 /* paired with cmpxchg() below */
179 ctx = locks_inode_context(inode);
180 if (likely(ctx) || type == F_UNLCK)
183 ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
187 spin_lock_init(&ctx->flc_lock);
188 INIT_LIST_HEAD(&ctx->flc_flock);
189 INIT_LIST_HEAD(&ctx->flc_posix);
190 INIT_LIST_HEAD(&ctx->flc_lease);
193 * Assign the pointer if it's not already assigned. If it is, then
194 * free the context we just allocated.
196 if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
197 kmem_cache_free(flctx_cache, ctx);
198 ctx = locks_inode_context(inode);
201 trace_locks_get_lock_context(inode, type, ctx);
206 locks_dump_ctx_list(struct list_head *list, char *list_type)
208 struct file_lock *fl;
210 list_for_each_entry(fl, list, fl_list) {
211 pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
216 locks_check_ctx_lists(struct inode *inode)
218 struct file_lock_context *ctx = inode->i_flctx;
220 if (unlikely(!list_empty(&ctx->flc_flock) ||
221 !list_empty(&ctx->flc_posix) ||
222 !list_empty(&ctx->flc_lease))) {
223 pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
224 MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
226 locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
227 locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
228 locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
233 locks_check_ctx_file_list(struct file *filp, struct list_head *list,
236 struct file_lock *fl;
237 struct inode *inode = file_inode(filp);
239 list_for_each_entry(fl, list, fl_list)
240 if (fl->fl_file == filp)
241 pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
242 " fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
243 list_type, MAJOR(inode->i_sb->s_dev),
244 MINOR(inode->i_sb->s_dev), inode->i_ino,
245 fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
249 locks_free_lock_context(struct inode *inode)
251 struct file_lock_context *ctx = locks_inode_context(inode);
254 locks_check_ctx_lists(inode);
255 kmem_cache_free(flctx_cache, ctx);
259 static void locks_init_lock_heads(struct file_lock *fl)
261 INIT_HLIST_NODE(&fl->fl_link);
262 INIT_LIST_HEAD(&fl->fl_list);
263 INIT_LIST_HEAD(&fl->fl_blocked_requests);
264 INIT_LIST_HEAD(&fl->fl_blocked_member);
265 init_waitqueue_head(&fl->fl_wait);
268 /* Allocate an empty lock structure. */
269 struct file_lock *locks_alloc_lock(void)
271 struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
274 locks_init_lock_heads(fl);
278 EXPORT_SYMBOL_GPL(locks_alloc_lock);
280 void locks_release_private(struct file_lock *fl)
282 BUG_ON(waitqueue_active(&fl->fl_wait));
283 BUG_ON(!list_empty(&fl->fl_list));
284 BUG_ON(!list_empty(&fl->fl_blocked_requests));
285 BUG_ON(!list_empty(&fl->fl_blocked_member));
286 BUG_ON(!hlist_unhashed(&fl->fl_link));
289 if (fl->fl_ops->fl_release_private)
290 fl->fl_ops->fl_release_private(fl);
295 if (fl->fl_lmops->lm_put_owner) {
296 fl->fl_lmops->lm_put_owner(fl->fl_owner);
302 EXPORT_SYMBOL_GPL(locks_release_private);
305 * locks_owner_has_blockers - Check for blocking lock requests
306 * @flctx: file lock context
310 * %true: @owner has at least one blocker
311 * %false: @owner has no blockers
313 bool locks_owner_has_blockers(struct file_lock_context *flctx,
316 struct file_lock *fl;
318 spin_lock(&flctx->flc_lock);
319 list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
320 if (fl->fl_owner != owner)
322 if (!list_empty(&fl->fl_blocked_requests)) {
323 spin_unlock(&flctx->flc_lock);
327 spin_unlock(&flctx->flc_lock);
330 EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
332 /* Free a lock which is not in use. */
333 void locks_free_lock(struct file_lock *fl)
335 locks_release_private(fl);
336 kmem_cache_free(filelock_cache, fl);
338 EXPORT_SYMBOL(locks_free_lock);
341 locks_dispose_list(struct list_head *dispose)
343 struct file_lock *fl;
345 while (!list_empty(dispose)) {
346 fl = list_first_entry(dispose, struct file_lock, fl_list);
347 list_del_init(&fl->fl_list);
352 void locks_init_lock(struct file_lock *fl)
354 memset(fl, 0, sizeof(struct file_lock));
355 locks_init_lock_heads(fl);
357 EXPORT_SYMBOL(locks_init_lock);
360 * Initialize a new lock from an existing file_lock structure.
362 void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
364 new->fl_owner = fl->fl_owner;
365 new->fl_pid = fl->fl_pid;
367 new->fl_flags = fl->fl_flags;
368 new->fl_type = fl->fl_type;
369 new->fl_start = fl->fl_start;
370 new->fl_end = fl->fl_end;
371 new->fl_lmops = fl->fl_lmops;
375 if (fl->fl_lmops->lm_get_owner)
376 fl->fl_lmops->lm_get_owner(fl->fl_owner);
379 EXPORT_SYMBOL(locks_copy_conflock);
381 void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
383 /* "new" must be a freshly-initialized lock */
384 WARN_ON_ONCE(new->fl_ops);
386 locks_copy_conflock(new, fl);
388 new->fl_file = fl->fl_file;
389 new->fl_ops = fl->fl_ops;
392 if (fl->fl_ops->fl_copy_lock)
393 fl->fl_ops->fl_copy_lock(new, fl);
396 EXPORT_SYMBOL(locks_copy_lock);
398 static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
403 * As ctx->flc_lock is held, new requests cannot be added to
404 * ->fl_blocked_requests, so we don't need a lock to check if it
407 if (list_empty(&fl->fl_blocked_requests))
409 spin_lock(&blocked_lock_lock);
410 list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests);
411 list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member)
413 spin_unlock(&blocked_lock_lock);
416 static inline int flock_translate_cmd(int cmd) {
428 /* Fill in a file_lock structure with an appropriate FLOCK lock. */
429 static void flock_make_lock(struct file *filp, struct file_lock *fl, int type)
435 fl->fl_pid = current->tgid;
436 fl->fl_flags = FL_FLOCK;
438 fl->fl_end = OFFSET_MAX;
441 static int assign_type(struct file_lock *fl, int type)
455 static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
458 switch (l->l_whence) {
463 fl->fl_start = filp->f_pos;
466 fl->fl_start = i_size_read(file_inode(filp));
471 if (l->l_start > OFFSET_MAX - fl->fl_start)
473 fl->fl_start += l->l_start;
474 if (fl->fl_start < 0)
477 /* POSIX-1996 leaves the case l->l_len < 0 undefined;
478 POSIX-2001 defines it. */
480 if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
482 fl->fl_end = fl->fl_start + (l->l_len - 1);
484 } else if (l->l_len < 0) {
485 if (fl->fl_start + l->l_len < 0)
487 fl->fl_end = fl->fl_start - 1;
488 fl->fl_start += l->l_len;
490 fl->fl_end = OFFSET_MAX;
492 fl->fl_owner = current->files;
493 fl->fl_pid = current->tgid;
495 fl->fl_flags = FL_POSIX;
499 return assign_type(fl, l->l_type);
502 /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
505 static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
508 struct flock64 ll = {
510 .l_whence = l->l_whence,
511 .l_start = l->l_start,
515 return flock64_to_posix_lock(filp, fl, &ll);
518 /* default lease lock manager operations */
520 lease_break_callback(struct file_lock *fl)
522 kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
527 lease_setup(struct file_lock *fl, void **priv)
529 struct file *filp = fl->fl_file;
530 struct fasync_struct *fa = *priv;
533 * fasync_insert_entry() returns the old entry if any. If there was no
534 * old entry, then it used "priv" and inserted it into the fasync list.
535 * Clear the pointer to indicate that it shouldn't be freed.
537 if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
540 __f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
543 static const struct lock_manager_operations lease_manager_ops = {
544 .lm_break = lease_break_callback,
545 .lm_change = lease_modify,
546 .lm_setup = lease_setup,
550 * Initialize a lease, use the default lock manager operations
552 static int lease_init(struct file *filp, int type, struct file_lock *fl)
554 if (assign_type(fl, type) != 0)
558 fl->fl_pid = current->tgid;
561 fl->fl_flags = FL_LEASE;
563 fl->fl_end = OFFSET_MAX;
565 fl->fl_lmops = &lease_manager_ops;
569 /* Allocate a file_lock initialised to this type of lease */
570 static struct file_lock *lease_alloc(struct file *filp, int type)
572 struct file_lock *fl = locks_alloc_lock();
576 return ERR_PTR(error);
578 error = lease_init(filp, type, fl);
581 return ERR_PTR(error);
586 /* Check if two locks overlap each other.
588 static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
590 return ((fl1->fl_end >= fl2->fl_start) &&
591 (fl2->fl_end >= fl1->fl_start));
595 * Check whether two locks have the same owner.
597 static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
599 return fl1->fl_owner == fl2->fl_owner;
602 /* Must be called with the flc_lock held! */
603 static void locks_insert_global_locks(struct file_lock *fl)
605 struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
607 percpu_rwsem_assert_held(&file_rwsem);
609 spin_lock(&fll->lock);
610 fl->fl_link_cpu = smp_processor_id();
611 hlist_add_head(&fl->fl_link, &fll->hlist);
612 spin_unlock(&fll->lock);
615 /* Must be called with the flc_lock held! */
616 static void locks_delete_global_locks(struct file_lock *fl)
618 struct file_lock_list_struct *fll;
620 percpu_rwsem_assert_held(&file_rwsem);
623 * Avoid taking lock if already unhashed. This is safe since this check
624 * is done while holding the flc_lock, and new insertions into the list
625 * also require that it be held.
627 if (hlist_unhashed(&fl->fl_link))
630 fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
631 spin_lock(&fll->lock);
632 hlist_del_init(&fl->fl_link);
633 spin_unlock(&fll->lock);
637 posix_owner_key(struct file_lock *fl)
639 return (unsigned long)fl->fl_owner;
642 static void locks_insert_global_blocked(struct file_lock *waiter)
644 lockdep_assert_held(&blocked_lock_lock);
646 hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
649 static void locks_delete_global_blocked(struct file_lock *waiter)
651 lockdep_assert_held(&blocked_lock_lock);
653 hash_del(&waiter->fl_link);
656 /* Remove waiter from blocker's block list.
657 * When blocker ends up pointing to itself then the list is empty.
659 * Must be called with blocked_lock_lock held.
661 static void __locks_delete_block(struct file_lock *waiter)
663 locks_delete_global_blocked(waiter);
664 list_del_init(&waiter->fl_blocked_member);
667 static void __locks_wake_up_blocks(struct file_lock *blocker)
669 while (!list_empty(&blocker->fl_blocked_requests)) {
670 struct file_lock *waiter;
672 waiter = list_first_entry(&blocker->fl_blocked_requests,
673 struct file_lock, fl_blocked_member);
674 __locks_delete_block(waiter);
675 if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
676 waiter->fl_lmops->lm_notify(waiter);
678 wake_up(&waiter->fl_wait);
681 * The setting of fl_blocker to NULL marks the "done"
682 * point in deleting a block. Paired with acquire at the top
683 * of locks_delete_block().
685 smp_store_release(&waiter->fl_blocker, NULL);
690 * locks_delete_block - stop waiting for a file lock
691 * @waiter: the lock which was waiting
693 * lockd/nfsd need to disconnect the lock while working on it.
695 int locks_delete_block(struct file_lock *waiter)
697 int status = -ENOENT;
700 * If fl_blocker is NULL, it won't be set again as this thread "owns"
701 * the lock and is the only one that might try to claim the lock.
703 * We use acquire/release to manage fl_blocker so that we can
704 * optimize away taking the blocked_lock_lock in many cases.
706 * The smp_load_acquire guarantees two things:
708 * 1/ that fl_blocked_requests can be tested locklessly. If something
709 * was recently added to that list it must have been in a locked region
710 * *before* the locked region when fl_blocker was set to NULL.
712 * 2/ that no other thread is accessing 'waiter', so it is safe to free
713 * it. __locks_wake_up_blocks is careful not to touch waiter after
714 * fl_blocker is released.
716 * If a lockless check of fl_blocker shows it to be NULL, we know that
717 * no new locks can be inserted into its fl_blocked_requests list, and
718 * can avoid doing anything further if the list is empty.
720 if (!smp_load_acquire(&waiter->fl_blocker) &&
721 list_empty(&waiter->fl_blocked_requests))
724 spin_lock(&blocked_lock_lock);
725 if (waiter->fl_blocker)
727 __locks_wake_up_blocks(waiter);
728 __locks_delete_block(waiter);
731 * The setting of fl_blocker to NULL marks the "done" point in deleting
732 * a block. Paired with acquire at the top of this function.
734 smp_store_release(&waiter->fl_blocker, NULL);
735 spin_unlock(&blocked_lock_lock);
738 EXPORT_SYMBOL(locks_delete_block);
740 /* Insert waiter into blocker's block list.
741 * We use a circular list so that processes can be easily woken up in
742 * the order they blocked. The documentation doesn't require this but
743 * it seems like the reasonable thing to do.
745 * Must be called with both the flc_lock and blocked_lock_lock held. The
746 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
747 * but by ensuring that the flc_lock is also held on insertions we can avoid
748 * taking the blocked_lock_lock in some cases when we see that the
749 * fl_blocked_requests list is empty.
751 * Rather than just adding to the list, we check for conflicts with any existing
752 * waiters, and add beneath any waiter that blocks the new waiter.
753 * Thus wakeups don't happen until needed.
755 static void __locks_insert_block(struct file_lock *blocker,
756 struct file_lock *waiter,
757 bool conflict(struct file_lock *,
760 struct file_lock *fl;
761 BUG_ON(!list_empty(&waiter->fl_blocked_member));
764 list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member)
765 if (conflict(fl, waiter)) {
769 waiter->fl_blocker = blocker;
770 list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
771 if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
772 locks_insert_global_blocked(waiter);
774 /* The requests in waiter->fl_blocked are known to conflict with
775 * waiter, but might not conflict with blocker, or the requests
776 * and lock which block it. So they all need to be woken.
778 __locks_wake_up_blocks(waiter);
781 /* Must be called with flc_lock held. */
782 static void locks_insert_block(struct file_lock *blocker,
783 struct file_lock *waiter,
784 bool conflict(struct file_lock *,
787 spin_lock(&blocked_lock_lock);
788 __locks_insert_block(blocker, waiter, conflict);
789 spin_unlock(&blocked_lock_lock);
793 * Wake up processes blocked waiting for blocker.
795 * Must be called with the inode->flc_lock held!
797 static void locks_wake_up_blocks(struct file_lock *blocker)
800 * Avoid taking global lock if list is empty. This is safe since new
801 * blocked requests are only added to the list under the flc_lock, and
802 * the flc_lock is always held here. Note that removal from the
803 * fl_blocked_requests list does not require the flc_lock, so we must
804 * recheck list_empty() after acquiring the blocked_lock_lock.
806 if (list_empty(&blocker->fl_blocked_requests))
809 spin_lock(&blocked_lock_lock);
810 __locks_wake_up_blocks(blocker);
811 spin_unlock(&blocked_lock_lock);
815 locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
817 list_add_tail(&fl->fl_list, before);
818 locks_insert_global_locks(fl);
822 locks_unlink_lock_ctx(struct file_lock *fl)
824 locks_delete_global_locks(fl);
825 list_del_init(&fl->fl_list);
826 locks_wake_up_blocks(fl);
830 locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
832 locks_unlink_lock_ctx(fl);
834 list_add(&fl->fl_list, dispose);
839 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
840 * checks for shared/exclusive status of overlapping locks.
842 static bool locks_conflict(struct file_lock *caller_fl,
843 struct file_lock *sys_fl)
845 if (sys_fl->fl_type == F_WRLCK)
847 if (caller_fl->fl_type == F_WRLCK)
852 /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
853 * checking before calling the locks_conflict().
855 static bool posix_locks_conflict(struct file_lock *caller_fl,
856 struct file_lock *sys_fl)
858 /* POSIX locks owned by the same process do not conflict with
861 if (posix_same_owner(caller_fl, sys_fl))
864 /* Check whether they overlap */
865 if (!locks_overlap(caller_fl, sys_fl))
868 return locks_conflict(caller_fl, sys_fl);
871 /* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK
872 * path so checks for additional GETLK-specific things like F_UNLCK.
874 static bool posix_test_locks_conflict(struct file_lock *caller_fl,
875 struct file_lock *sys_fl)
877 /* F_UNLCK checks any locks on the same fd. */
878 if (caller_fl->fl_type == F_UNLCK) {
879 if (!posix_same_owner(caller_fl, sys_fl))
881 return locks_overlap(caller_fl, sys_fl);
883 return posix_locks_conflict(caller_fl, sys_fl);
886 /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
887 * checking before calling the locks_conflict().
889 static bool flock_locks_conflict(struct file_lock *caller_fl,
890 struct file_lock *sys_fl)
892 /* FLOCK locks referring to the same filp do not conflict with
895 if (caller_fl->fl_file == sys_fl->fl_file)
898 return locks_conflict(caller_fl, sys_fl);
902 posix_test_lock(struct file *filp, struct file_lock *fl)
904 struct file_lock *cfl;
905 struct file_lock_context *ctx;
906 struct inode *inode = file_inode(filp);
910 ctx = locks_inode_context(inode);
911 if (!ctx || list_empty_careful(&ctx->flc_posix)) {
912 fl->fl_type = F_UNLCK;
917 spin_lock(&ctx->flc_lock);
918 list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
919 if (!posix_test_locks_conflict(fl, cfl))
921 if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_expirable
922 && (*cfl->fl_lmops->lm_lock_expirable)(cfl)) {
923 owner = cfl->fl_lmops->lm_mod_owner;
924 func = cfl->fl_lmops->lm_expire_lock;
926 spin_unlock(&ctx->flc_lock);
931 locks_copy_conflock(fl, cfl);
934 fl->fl_type = F_UNLCK;
936 spin_unlock(&ctx->flc_lock);
939 EXPORT_SYMBOL(posix_test_lock);
942 * Deadlock detection:
944 * We attempt to detect deadlocks that are due purely to posix file
947 * We assume that a task can be waiting for at most one lock at a time.
948 * So for any acquired lock, the process holding that lock may be
949 * waiting on at most one other lock. That lock in turns may be held by
950 * someone waiting for at most one other lock. Given a requested lock
951 * caller_fl which is about to wait for a conflicting lock block_fl, we
952 * follow this chain of waiters to ensure we are not about to create a
955 * Since we do this before we ever put a process to sleep on a lock, we
956 * are ensured that there is never a cycle; that is what guarantees that
957 * the while() loop in posix_locks_deadlock() eventually completes.
959 * Note: the above assumption may not be true when handling lock
960 * requests from a broken NFS client. It may also fail in the presence
961 * of tasks (such as posix threads) sharing the same open file table.
962 * To handle those cases, we just bail out after a few iterations.
964 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
965 * Because the owner is not even nominally tied to a thread of
966 * execution, the deadlock detection below can't reasonably work well. Just
969 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
970 * locks that just checks for the case where two tasks are attempting to
971 * upgrade from read to write locks on the same inode.
974 #define MAX_DEADLK_ITERATIONS 10
976 /* Find a lock that the owner of the given block_fl is blocking on. */
977 static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
979 struct file_lock *fl;
981 hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
982 if (posix_same_owner(fl, block_fl)) {
983 while (fl->fl_blocker)
991 /* Must be called with the blocked_lock_lock held! */
992 static int posix_locks_deadlock(struct file_lock *caller_fl,
993 struct file_lock *block_fl)
997 lockdep_assert_held(&blocked_lock_lock);
1000 * This deadlock detector can't reasonably detect deadlocks with
1001 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
1003 if (IS_OFDLCK(caller_fl))
1006 while ((block_fl = what_owner_is_waiting_for(block_fl))) {
1007 if (i++ > MAX_DEADLK_ITERATIONS)
1009 if (posix_same_owner(caller_fl, block_fl))
1015 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1016 * after any leases, but before any posix locks.
1018 * Note that if called with an FL_EXISTS argument, the caller may determine
1019 * whether or not a lock was successfully freed by testing the return
1020 * value for -ENOENT.
1022 static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1024 struct file_lock *new_fl = NULL;
1025 struct file_lock *fl;
1026 struct file_lock_context *ctx;
1031 ctx = locks_get_lock_context(inode, request->fl_type);
1033 if (request->fl_type != F_UNLCK)
1035 return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
1038 if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
1039 new_fl = locks_alloc_lock();
1044 percpu_down_read(&file_rwsem);
1045 spin_lock(&ctx->flc_lock);
1046 if (request->fl_flags & FL_ACCESS)
1049 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1050 if (request->fl_file != fl->fl_file)
1052 if (request->fl_type == fl->fl_type)
1055 locks_delete_lock_ctx(fl, &dispose);
1059 if (request->fl_type == F_UNLCK) {
1060 if ((request->fl_flags & FL_EXISTS) && !found)
1066 list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1067 if (!flock_locks_conflict(request, fl))
1070 if (!(request->fl_flags & FL_SLEEP))
1072 error = FILE_LOCK_DEFERRED;
1073 locks_insert_block(fl, request, flock_locks_conflict);
1076 if (request->fl_flags & FL_ACCESS)
1078 locks_copy_lock(new_fl, request);
1079 locks_move_blocks(new_fl, request);
1080 locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
1085 spin_unlock(&ctx->flc_lock);
1086 percpu_up_read(&file_rwsem);
1088 locks_free_lock(new_fl);
1089 locks_dispose_list(&dispose);
1090 trace_flock_lock_inode(inode, request, error);
1094 static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1095 struct file_lock *conflock)
1097 struct file_lock *fl, *tmp;
1098 struct file_lock *new_fl = NULL;
1099 struct file_lock *new_fl2 = NULL;
1100 struct file_lock *left = NULL;
1101 struct file_lock *right = NULL;
1102 struct file_lock_context *ctx;
1109 ctx = locks_get_lock_context(inode, request->fl_type);
1111 return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
1114 * We may need two file_lock structures for this operation,
1115 * so we get them in advance to avoid races.
1117 * In some cases we can be sure, that no new locks will be needed
1119 if (!(request->fl_flags & FL_ACCESS) &&
1120 (request->fl_type != F_UNLCK ||
1121 request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1122 new_fl = locks_alloc_lock();
1123 new_fl2 = locks_alloc_lock();
1127 percpu_down_read(&file_rwsem);
1128 spin_lock(&ctx->flc_lock);
1130 * New lock request. Walk all POSIX locks and look for conflicts. If
1131 * there are any, either return error or put the request on the
1132 * blocker's list of waiters and the global blocked_hash.
1134 if (request->fl_type != F_UNLCK) {
1135 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1136 if (!posix_locks_conflict(request, fl))
1138 if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable
1139 && (*fl->fl_lmops->lm_lock_expirable)(fl)) {
1140 owner = fl->fl_lmops->lm_mod_owner;
1141 func = fl->fl_lmops->lm_expire_lock;
1142 __module_get(owner);
1143 spin_unlock(&ctx->flc_lock);
1144 percpu_up_read(&file_rwsem);
1150 locks_copy_conflock(conflock, fl);
1152 if (!(request->fl_flags & FL_SLEEP))
1155 * Deadlock detection and insertion into the blocked
1156 * locks list must be done while holding the same lock!
1159 spin_lock(&blocked_lock_lock);
1161 * Ensure that we don't find any locks blocked on this
1162 * request during deadlock detection.
1164 __locks_wake_up_blocks(request);
1165 if (likely(!posix_locks_deadlock(request, fl))) {
1166 error = FILE_LOCK_DEFERRED;
1167 __locks_insert_block(fl, request,
1168 posix_locks_conflict);
1170 spin_unlock(&blocked_lock_lock);
1175 /* If we're just looking for a conflict, we're done. */
1177 if (request->fl_flags & FL_ACCESS)
1180 /* Find the first old lock with the same owner as the new lock */
1181 list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1182 if (posix_same_owner(request, fl))
1186 /* Process locks with this owner. */
1187 list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1188 if (!posix_same_owner(request, fl))
1191 /* Detect adjacent or overlapping regions (if same lock type) */
1192 if (request->fl_type == fl->fl_type) {
1193 /* In all comparisons of start vs end, use
1194 * "start - 1" rather than "end + 1". If end
1195 * is OFFSET_MAX, end + 1 will become negative.
1197 if (fl->fl_end < request->fl_start - 1)
1199 /* If the next lock in the list has entirely bigger
1200 * addresses than the new one, insert the lock here.
1202 if (fl->fl_start - 1 > request->fl_end)
1205 /* If we come here, the new and old lock are of the
1206 * same type and adjacent or overlapping. Make one
1207 * lock yielding from the lower start address of both
1208 * locks to the higher end address.
1210 if (fl->fl_start > request->fl_start)
1211 fl->fl_start = request->fl_start;
1213 request->fl_start = fl->fl_start;
1214 if (fl->fl_end < request->fl_end)
1215 fl->fl_end = request->fl_end;
1217 request->fl_end = fl->fl_end;
1219 locks_delete_lock_ctx(fl, &dispose);
1225 /* Processing for different lock types is a bit
1228 if (fl->fl_end < request->fl_start)
1230 if (fl->fl_start > request->fl_end)
1232 if (request->fl_type == F_UNLCK)
1234 if (fl->fl_start < request->fl_start)
1236 /* If the next lock in the list has a higher end
1237 * address than the new one, insert the new one here.
1239 if (fl->fl_end > request->fl_end) {
1243 if (fl->fl_start >= request->fl_start) {
1244 /* The new lock completely replaces an old
1245 * one (This may happen several times).
1248 locks_delete_lock_ctx(fl, &dispose);
1252 * Replace the old lock with new_fl, and
1253 * remove the old one. It's safe to do the
1254 * insert here since we know that we won't be
1255 * using new_fl later, and that the lock is
1256 * just replacing an existing lock.
1261 locks_copy_lock(new_fl, request);
1262 locks_move_blocks(new_fl, request);
1265 locks_insert_lock_ctx(request, &fl->fl_list);
1266 locks_delete_lock_ctx(fl, &dispose);
1273 * The above code only modifies existing locks in case of merging or
1274 * replacing. If new lock(s) need to be inserted all modifications are
1275 * done below this, so it's safe yet to bail out.
1277 error = -ENOLCK; /* "no luck" */
1278 if (right && left == right && !new_fl2)
1283 if (request->fl_type == F_UNLCK) {
1284 if (request->fl_flags & FL_EXISTS)
1293 locks_copy_lock(new_fl, request);
1294 locks_move_blocks(new_fl, request);
1295 locks_insert_lock_ctx(new_fl, &fl->fl_list);
1300 if (left == right) {
1301 /* The new lock breaks the old one in two pieces,
1302 * so we have to use the second new lock.
1306 locks_copy_lock(left, right);
1307 locks_insert_lock_ctx(left, &fl->fl_list);
1309 right->fl_start = request->fl_end + 1;
1310 locks_wake_up_blocks(right);
1313 left->fl_end = request->fl_start - 1;
1314 locks_wake_up_blocks(left);
1317 spin_unlock(&ctx->flc_lock);
1318 percpu_up_read(&file_rwsem);
1319 trace_posix_lock_inode(inode, request, error);
1321 * Free any unused locks.
1324 locks_free_lock(new_fl);
1326 locks_free_lock(new_fl2);
1327 locks_dispose_list(&dispose);
1333 * posix_lock_file - Apply a POSIX-style lock to a file
1334 * @filp: The file to apply the lock to
1335 * @fl: The lock to be applied
1336 * @conflock: Place to return a copy of the conflicting lock, if found.
1338 * Add a POSIX style lock to a file.
1339 * We merge adjacent & overlapping locks whenever possible.
1340 * POSIX locks are sorted by owner task, then by starting address
1342 * Note that if called with an FL_EXISTS argument, the caller may determine
1343 * whether or not a lock was successfully freed by testing the return
1344 * value for -ENOENT.
1346 int posix_lock_file(struct file *filp, struct file_lock *fl,
1347 struct file_lock *conflock)
1349 return posix_lock_inode(file_inode(filp), fl, conflock);
1351 EXPORT_SYMBOL(posix_lock_file);
1354 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1355 * @inode: inode of file to which lock request should be applied
1356 * @fl: The lock to be applied
1358 * Apply a POSIX style lock request to an inode.
1360 static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1365 error = posix_lock_inode(inode, fl, NULL);
1366 if (error != FILE_LOCK_DEFERRED)
1368 error = wait_event_interruptible(fl->fl_wait,
1369 list_empty(&fl->fl_blocked_member));
1373 locks_delete_block(fl);
1377 static void lease_clear_pending(struct file_lock *fl, int arg)
1381 fl->fl_flags &= ~FL_UNLOCK_PENDING;
1384 fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1388 /* We already had a lease on this file; just change its type */
1389 int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1391 int error = assign_type(fl, arg);
1395 lease_clear_pending(fl, arg);
1396 locks_wake_up_blocks(fl);
1397 if (arg == F_UNLCK) {
1398 struct file *filp = fl->fl_file;
1401 filp->f_owner.signum = 0;
1402 fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1403 if (fl->fl_fasync != NULL) {
1404 printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1405 fl->fl_fasync = NULL;
1407 locks_delete_lock_ctx(fl, dispose);
1411 EXPORT_SYMBOL(lease_modify);
1413 static bool past_time(unsigned long then)
1416 /* 0 is a special value meaning "this never expires": */
1418 return time_after(jiffies, then);
1421 static void time_out_leases(struct inode *inode, struct list_head *dispose)
1423 struct file_lock_context *ctx = inode->i_flctx;
1424 struct file_lock *fl, *tmp;
1426 lockdep_assert_held(&ctx->flc_lock);
1428 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1429 trace_time_out_leases(inode, fl);
1430 if (past_time(fl->fl_downgrade_time))
1431 lease_modify(fl, F_RDLCK, dispose);
1432 if (past_time(fl->fl_break_time))
1433 lease_modify(fl, F_UNLCK, dispose);
1437 static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1441 if (lease->fl_lmops->lm_breaker_owns_lease
1442 && lease->fl_lmops->lm_breaker_owns_lease(lease))
1444 if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
1448 if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
1453 rc = locks_conflict(breaker, lease);
1455 trace_leases_conflict(rc, lease, breaker);
1460 any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1462 struct file_lock_context *ctx = inode->i_flctx;
1463 struct file_lock *fl;
1465 lockdep_assert_held(&ctx->flc_lock);
1467 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1468 if (leases_conflict(fl, breaker))
1475 * __break_lease - revoke all outstanding leases on file
1476 * @inode: the inode of the file to return
1477 * @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1479 * @type: FL_LEASE: break leases and delegations; FL_DELEG: break
1482 * break_lease (inlined for speed) has checked there already is at least
1483 * some kind of lock (maybe a lease) on this file. Leases are broken on
1484 * a call to open() or truncate(). This function can sleep unless you
1485 * specified %O_NONBLOCK to your open().
1487 int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1490 struct file_lock_context *ctx;
1491 struct file_lock *new_fl, *fl, *tmp;
1492 unsigned long break_time;
1493 int want_write = (mode & O_ACCMODE) != O_RDONLY;
1496 new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1498 return PTR_ERR(new_fl);
1499 new_fl->fl_flags = type;
1501 /* typically we will check that ctx is non-NULL before calling */
1502 ctx = locks_inode_context(inode);
1508 percpu_down_read(&file_rwsem);
1509 spin_lock(&ctx->flc_lock);
1511 time_out_leases(inode, &dispose);
1513 if (!any_leases_conflict(inode, new_fl))
1517 if (lease_break_time > 0) {
1518 break_time = jiffies + lease_break_time * HZ;
1519 if (break_time == 0)
1520 break_time++; /* so that 0 means no break time */
1523 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1524 if (!leases_conflict(fl, new_fl))
1527 if (fl->fl_flags & FL_UNLOCK_PENDING)
1529 fl->fl_flags |= FL_UNLOCK_PENDING;
1530 fl->fl_break_time = break_time;
1532 if (lease_breaking(fl))
1534 fl->fl_flags |= FL_DOWNGRADE_PENDING;
1535 fl->fl_downgrade_time = break_time;
1537 if (fl->fl_lmops->lm_break(fl))
1538 locks_delete_lock_ctx(fl, &dispose);
1541 if (list_empty(&ctx->flc_lease))
1544 if (mode & O_NONBLOCK) {
1545 trace_break_lease_noblock(inode, new_fl);
1546 error = -EWOULDBLOCK;
1551 fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1552 break_time = fl->fl_break_time;
1553 if (break_time != 0)
1554 break_time -= jiffies;
1555 if (break_time == 0)
1557 locks_insert_block(fl, new_fl, leases_conflict);
1558 trace_break_lease_block(inode, new_fl);
1559 spin_unlock(&ctx->flc_lock);
1560 percpu_up_read(&file_rwsem);
1562 locks_dispose_list(&dispose);
1563 error = wait_event_interruptible_timeout(new_fl->fl_wait,
1564 list_empty(&new_fl->fl_blocked_member),
1567 percpu_down_read(&file_rwsem);
1568 spin_lock(&ctx->flc_lock);
1569 trace_break_lease_unblock(inode, new_fl);
1570 locks_delete_block(new_fl);
1573 * Wait for the next conflicting lease that has not been
1577 time_out_leases(inode, &dispose);
1578 if (any_leases_conflict(inode, new_fl))
1583 spin_unlock(&ctx->flc_lock);
1584 percpu_up_read(&file_rwsem);
1585 locks_dispose_list(&dispose);
1587 locks_free_lock(new_fl);
1590 EXPORT_SYMBOL(__break_lease);
1593 * lease_get_mtime - update modified time of an inode with exclusive lease
1595 * @time: pointer to a timespec which contains the last modified time
1597 * This is to force NFS clients to flush their caches for files with
1598 * exclusive leases. The justification is that if someone has an
1599 * exclusive lease, then they could be modifying it.
1601 void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1603 bool has_lease = false;
1604 struct file_lock_context *ctx;
1605 struct file_lock *fl;
1607 ctx = locks_inode_context(inode);
1608 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1609 spin_lock(&ctx->flc_lock);
1610 fl = list_first_entry_or_null(&ctx->flc_lease,
1611 struct file_lock, fl_list);
1612 if (fl && (fl->fl_type == F_WRLCK))
1614 spin_unlock(&ctx->flc_lock);
1618 *time = current_time(inode);
1620 EXPORT_SYMBOL(lease_get_mtime);
1623 * fcntl_getlease - Enquire what lease is currently active
1626 * The value returned by this function will be one of
1627 * (if no lease break is pending):
1629 * %F_RDLCK to indicate a shared lease is held.
1631 * %F_WRLCK to indicate an exclusive lease is held.
1633 * %F_UNLCK to indicate no lease is held.
1635 * (if a lease break is pending):
1637 * %F_RDLCK to indicate an exclusive lease needs to be
1638 * changed to a shared lease (or removed).
1640 * %F_UNLCK to indicate the lease needs to be removed.
1642 * XXX: sfr & willy disagree over whether F_INPROGRESS
1643 * should be returned to userspace.
1645 int fcntl_getlease(struct file *filp)
1647 struct file_lock *fl;
1648 struct inode *inode = file_inode(filp);
1649 struct file_lock_context *ctx;
1653 ctx = locks_inode_context(inode);
1654 if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1655 percpu_down_read(&file_rwsem);
1656 spin_lock(&ctx->flc_lock);
1657 time_out_leases(inode, &dispose);
1658 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1659 if (fl->fl_file != filp)
1661 type = target_leasetype(fl);
1664 spin_unlock(&ctx->flc_lock);
1665 percpu_up_read(&file_rwsem);
1667 locks_dispose_list(&dispose);
1673 * check_conflicting_open - see if the given file points to an inode that has
1674 * an existing open that would conflict with the
1676 * @filp: file to check
1677 * @arg: type of lease that we're trying to acquire
1678 * @flags: current lock flags
1680 * Check to see if there's an existing open fd on this file that would
1681 * conflict with the lease we're trying to set.
1684 check_conflicting_open(struct file *filp, const int arg, int flags)
1686 struct inode *inode = file_inode(filp);
1687 int self_wcount = 0, self_rcount = 0;
1689 if (flags & FL_LAYOUT)
1691 if (flags & FL_DELEG)
1692 /* We leave these checks to the caller */
1696 return inode_is_open_for_write(inode) ? -EAGAIN : 0;
1697 else if (arg != F_WRLCK)
1701 * Make sure that only read/write count is from lease requestor.
1702 * Note that this will result in denying write leases when i_writecount
1703 * is negative, which is what we want. (We shouldn't grant write leases
1704 * on files open for execution.)
1706 if (filp->f_mode & FMODE_WRITE)
1708 else if (filp->f_mode & FMODE_READ)
1711 if (atomic_read(&inode->i_writecount) != self_wcount ||
1712 atomic_read(&inode->i_readcount) != self_rcount)
1719 generic_add_lease(struct file *filp, int arg, struct file_lock **flp, void **priv)
1721 struct file_lock *fl, *my_fl = NULL, *lease;
1722 struct inode *inode = file_inode(filp);
1723 struct file_lock_context *ctx;
1724 bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1729 trace_generic_add_lease(inode, lease);
1731 /* Note that arg is never F_UNLCK here */
1732 ctx = locks_get_lock_context(inode, arg);
1737 * In the delegation case we need mutual exclusion with
1738 * a number of operations that take the i_mutex. We trylock
1739 * because delegations are an optional optimization, and if
1740 * there's some chance of a conflict--we'd rather not
1741 * bother, maybe that's a sign this just isn't a good file to
1742 * hand out a delegation on.
1744 if (is_deleg && !inode_trylock(inode))
1747 percpu_down_read(&file_rwsem);
1748 spin_lock(&ctx->flc_lock);
1749 time_out_leases(inode, &dispose);
1750 error = check_conflicting_open(filp, arg, lease->fl_flags);
1755 * At this point, we know that if there is an exclusive
1756 * lease on this file, then we hold it on this filp
1757 * (otherwise our open of this file would have blocked).
1758 * And if we are trying to acquire an exclusive lease,
1759 * then the file is not open by anyone (including us)
1760 * except for this filp.
1763 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1764 if (fl->fl_file == filp &&
1765 fl->fl_owner == lease->fl_owner) {
1771 * No exclusive leases if someone else has a lease on
1777 * Modifying our existing lease is OK, but no getting a
1778 * new lease if someone else is opening for write:
1780 if (fl->fl_flags & FL_UNLOCK_PENDING)
1784 if (my_fl != NULL) {
1786 error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1796 locks_insert_lock_ctx(lease, &ctx->flc_lease);
1798 * The check in break_lease() is lockless. It's possible for another
1799 * open to race in after we did the earlier check for a conflicting
1800 * open but before the lease was inserted. Check again for a
1801 * conflicting open and cancel the lease if there is one.
1803 * We also add a barrier here to ensure that the insertion of the lock
1804 * precedes these checks.
1807 error = check_conflicting_open(filp, arg, lease->fl_flags);
1809 locks_unlink_lock_ctx(lease);
1814 if (lease->fl_lmops->lm_setup)
1815 lease->fl_lmops->lm_setup(lease, priv);
1817 spin_unlock(&ctx->flc_lock);
1818 percpu_up_read(&file_rwsem);
1819 locks_dispose_list(&dispose);
1821 inode_unlock(inode);
1822 if (!error && !my_fl)
1827 static int generic_delete_lease(struct file *filp, void *owner)
1829 int error = -EAGAIN;
1830 struct file_lock *fl, *victim = NULL;
1831 struct inode *inode = file_inode(filp);
1832 struct file_lock_context *ctx;
1835 ctx = locks_inode_context(inode);
1837 trace_generic_delete_lease(inode, NULL);
1841 percpu_down_read(&file_rwsem);
1842 spin_lock(&ctx->flc_lock);
1843 list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1844 if (fl->fl_file == filp &&
1845 fl->fl_owner == owner) {
1850 trace_generic_delete_lease(inode, victim);
1852 error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1853 spin_unlock(&ctx->flc_lock);
1854 percpu_up_read(&file_rwsem);
1855 locks_dispose_list(&dispose);
1860 * generic_setlease - sets a lease on an open file
1861 * @filp: file pointer
1862 * @arg: type of lease to obtain
1863 * @flp: input - file_lock to use, output - file_lock inserted
1864 * @priv: private data for lm_setup (may be NULL if lm_setup
1865 * doesn't require it)
1867 * The (input) flp->fl_lmops->lm_break function is required
1870 int generic_setlease(struct file *filp, int arg, struct file_lock **flp,
1873 struct inode *inode = file_inode(filp);
1874 vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode);
1877 if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE))
1879 if (!S_ISREG(inode->i_mode))
1881 error = security_file_lock(filp, arg);
1887 return generic_delete_lease(filp, *priv);
1890 if (!(*flp)->fl_lmops->lm_break) {
1895 return generic_add_lease(filp, arg, flp, priv);
1900 EXPORT_SYMBOL(generic_setlease);
1903 * Kernel subsystems can register to be notified on any attempt to set
1904 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
1905 * to close files that it may have cached when there is an attempt to set a
1906 * conflicting lease.
1908 static struct srcu_notifier_head lease_notifier_chain;
1911 lease_notifier_chain_init(void)
1913 srcu_init_notifier_head(&lease_notifier_chain);
1917 setlease_notifier(int arg, struct file_lock *lease)
1920 srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
1923 int lease_register_notifier(struct notifier_block *nb)
1925 return srcu_notifier_chain_register(&lease_notifier_chain, nb);
1927 EXPORT_SYMBOL_GPL(lease_register_notifier);
1929 void lease_unregister_notifier(struct notifier_block *nb)
1931 srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
1933 EXPORT_SYMBOL_GPL(lease_unregister_notifier);
1936 * vfs_setlease - sets a lease on an open file
1937 * @filp: file pointer
1938 * @arg: type of lease to obtain
1939 * @lease: file_lock to use when adding a lease
1940 * @priv: private info for lm_setup when adding a lease (may be
1941 * NULL if lm_setup doesn't require it)
1943 * Call this to establish a lease on the file. The "lease" argument is not
1944 * used for F_UNLCK requests and may be NULL. For commands that set or alter
1945 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
1946 * set; if not, this function will return -ENOLCK (and generate a scary-looking
1949 * The "priv" pointer is passed directly to the lm_setup function as-is. It
1950 * may be NULL if the lm_setup operation doesn't require it.
1953 vfs_setlease(struct file *filp, int arg, struct file_lock **lease, void **priv)
1956 setlease_notifier(arg, *lease);
1957 if (filp->f_op->setlease)
1958 return filp->f_op->setlease(filp, arg, lease, priv);
1960 return generic_setlease(filp, arg, lease, priv);
1962 EXPORT_SYMBOL_GPL(vfs_setlease);
1964 static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
1966 struct file_lock *fl;
1967 struct fasync_struct *new;
1970 fl = lease_alloc(filp, arg);
1974 new = fasync_alloc();
1976 locks_free_lock(fl);
1981 error = vfs_setlease(filp, arg, &fl, (void **)&new);
1983 locks_free_lock(fl);
1990 * fcntl_setlease - sets a lease on an open file
1991 * @fd: open file descriptor
1992 * @filp: file pointer
1993 * @arg: type of lease to obtain
1995 * Call this fcntl to establish a lease on the file.
1996 * Note that you also need to call %F_SETSIG to
1997 * receive a signal when the lease is broken.
1999 int fcntl_setlease(unsigned int fd, struct file *filp, int arg)
2002 return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2003 return do_fcntl_add_lease(fd, filp, arg);
2007 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2008 * @inode: inode of the file to apply to
2009 * @fl: The lock to be applied
2011 * Apply a FLOCK style lock request to an inode.
2013 static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2018 error = flock_lock_inode(inode, fl);
2019 if (error != FILE_LOCK_DEFERRED)
2021 error = wait_event_interruptible(fl->fl_wait,
2022 list_empty(&fl->fl_blocked_member));
2026 locks_delete_block(fl);
2031 * locks_lock_inode_wait - Apply a lock to an inode
2032 * @inode: inode of the file to apply to
2033 * @fl: The lock to be applied
2035 * Apply a POSIX or FLOCK style lock request to an inode.
2037 int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2040 switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
2042 res = posix_lock_inode_wait(inode, fl);
2045 res = flock_lock_inode_wait(inode, fl);
2052 EXPORT_SYMBOL(locks_lock_inode_wait);
2055 * sys_flock: - flock() system call.
2056 * @fd: the file descriptor to lock.
2057 * @cmd: the type of lock to apply.
2059 * Apply a %FL_FLOCK style lock to an open file descriptor.
2060 * The @cmd can be one of:
2062 * - %LOCK_SH -- a shared lock.
2063 * - %LOCK_EX -- an exclusive lock.
2064 * - %LOCK_UN -- remove an existing lock.
2065 * - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED)
2067 * %LOCK_MAND support has been removed from the kernel.
2069 SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2071 int can_sleep, error, type;
2072 struct file_lock fl;
2076 * LOCK_MAND locks were broken for a long time in that they never
2077 * conflicted with one another and didn't prevent any sort of open,
2078 * read or write activity.
2080 * Just ignore these requests now, to preserve legacy behavior, but
2081 * throw a warning to let people know that they don't actually work.
2083 if (cmd & LOCK_MAND) {
2084 pr_warn_once("%s(%d): Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n", current->comm, current->pid);
2088 type = flock_translate_cmd(cmd & ~LOCK_NB);
2097 if (type != F_UNLCK && !(f.file->f_mode & (FMODE_READ | FMODE_WRITE)))
2100 flock_make_lock(f.file, &fl, type);
2102 error = security_file_lock(f.file, fl.fl_type);
2106 can_sleep = !(cmd & LOCK_NB);
2108 fl.fl_flags |= FL_SLEEP;
2110 if (f.file->f_op->flock)
2111 error = f.file->f_op->flock(f.file,
2112 (can_sleep) ? F_SETLKW : F_SETLK,
2115 error = locks_lock_file_wait(f.file, &fl);
2117 locks_release_private(&fl);
2125 * vfs_test_lock - test file byte range lock
2126 * @filp: The file to test lock for
2127 * @fl: The lock to test; also used to hold result
2129 * Returns -ERRNO on failure. Indicates presence of conflicting lock by
2130 * setting conf->fl_type to something other than F_UNLCK.
2132 int vfs_test_lock(struct file *filp, struct file_lock *fl)
2134 WARN_ON_ONCE(filp != fl->fl_file);
2135 if (filp->f_op->lock)
2136 return filp->f_op->lock(filp, F_GETLK, fl);
2137 posix_test_lock(filp, fl);
2140 EXPORT_SYMBOL_GPL(vfs_test_lock);
2143 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2144 * @fl: The file_lock who's fl_pid should be translated
2145 * @ns: The namespace into which the pid should be translated
2147 * Used to translate a fl_pid into a namespace virtual pid number
2149 static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
2156 if (IS_REMOTELCK(fl))
2159 * If the flock owner process is dead and its pid has been already
2160 * freed, the translation below won't work, but we still want to show
2161 * flock owner pid number in init pidns.
2163 if (ns == &init_pid_ns)
2164 return (pid_t)fl->fl_pid;
2167 pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
2168 vnr = pid_nr_ns(pid, ns);
2173 static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2175 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2176 #if BITS_PER_LONG == 32
2178 * Make sure we can represent the posix lock via
2179 * legacy 32bit flock.
2181 if (fl->fl_start > OFFT_OFFSET_MAX)
2183 if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2186 flock->l_start = fl->fl_start;
2187 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2188 fl->fl_end - fl->fl_start + 1;
2189 flock->l_whence = 0;
2190 flock->l_type = fl->fl_type;
2194 #if BITS_PER_LONG == 32
2195 static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2197 flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2198 flock->l_start = fl->fl_start;
2199 flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2200 fl->fl_end - fl->fl_start + 1;
2201 flock->l_whence = 0;
2202 flock->l_type = fl->fl_type;
2206 /* Report the first existing lock that would conflict with l.
2207 * This implements the F_GETLK command of fcntl().
2209 int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2211 struct file_lock *fl;
2214 fl = locks_alloc_lock();
2218 if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2219 && flock->l_type != F_WRLCK)
2222 error = flock_to_posix_lock(filp, fl, flock);
2226 if (cmd == F_OFD_GETLK) {
2228 if (flock->l_pid != 0)
2231 fl->fl_flags |= FL_OFDLCK;
2232 fl->fl_owner = filp;
2235 error = vfs_test_lock(filp, fl);
2239 flock->l_type = fl->fl_type;
2240 if (fl->fl_type != F_UNLCK) {
2241 error = posix_lock_to_flock(flock, fl);
2246 locks_free_lock(fl);
2251 * vfs_lock_file - file byte range lock
2252 * @filp: The file to apply the lock to
2253 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2254 * @fl: The lock to be applied
2255 * @conf: Place to return a copy of the conflicting lock, if found.
2257 * A caller that doesn't care about the conflicting lock may pass NULL
2258 * as the final argument.
2260 * If the filesystem defines a private ->lock() method, then @conf will
2261 * be left unchanged; so a caller that cares should initialize it to
2262 * some acceptable default.
2264 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2265 * locks, the ->lock() interface may return asynchronously, before the lock has
2266 * been granted or denied by the underlying filesystem, if (and only if)
2267 * lm_grant is set. Additionally EXPORT_OP_ASYNC_LOCK in export_operations
2268 * flags need to be set.
2270 * Callers expecting ->lock() to return asynchronously will only use F_SETLK,
2271 * not F_SETLKW; they will set FL_SLEEP if (and only if) the request is for a
2272 * blocking lock. When ->lock() does return asynchronously, it must return
2273 * FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock request completes.
2274 * If the request is for non-blocking lock the file system should return
2275 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2276 * with the result. If the request timed out the callback routine will return a
2277 * nonzero return code and the file system should release the lock. The file
2278 * system is also responsible to keep a corresponding posix lock when it
2279 * grants a lock so the VFS can find out which locks are locally held and do
2280 * the correct lock cleanup when required.
2281 * The underlying filesystem must not drop the kernel lock or call
2282 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2285 int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2287 WARN_ON_ONCE(filp != fl->fl_file);
2288 if (filp->f_op->lock)
2289 return filp->f_op->lock(filp, cmd, fl);
2291 return posix_lock_file(filp, fl, conf);
2293 EXPORT_SYMBOL_GPL(vfs_lock_file);
2295 static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2296 struct file_lock *fl)
2300 error = security_file_lock(filp, fl->fl_type);
2305 error = vfs_lock_file(filp, cmd, fl, NULL);
2306 if (error != FILE_LOCK_DEFERRED)
2308 error = wait_event_interruptible(fl->fl_wait,
2309 list_empty(&fl->fl_blocked_member));
2313 locks_delete_block(fl);
2318 /* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2320 check_fmode_for_setlk(struct file_lock *fl)
2322 switch (fl->fl_type) {
2324 if (!(fl->fl_file->f_mode & FMODE_READ))
2328 if (!(fl->fl_file->f_mode & FMODE_WRITE))
2334 /* Apply the lock described by l to an open file descriptor.
2335 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2337 int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2338 struct flock *flock)
2340 struct file_lock *file_lock = locks_alloc_lock();
2341 struct inode *inode = file_inode(filp);
2345 if (file_lock == NULL)
2348 error = flock_to_posix_lock(filp, file_lock, flock);
2352 error = check_fmode_for_setlk(file_lock);
2357 * If the cmd is requesting file-private locks, then set the
2358 * FL_OFDLCK flag and override the owner.
2363 if (flock->l_pid != 0)
2367 file_lock->fl_flags |= FL_OFDLCK;
2368 file_lock->fl_owner = filp;
2372 if (flock->l_pid != 0)
2376 file_lock->fl_flags |= FL_OFDLCK;
2377 file_lock->fl_owner = filp;
2380 file_lock->fl_flags |= FL_SLEEP;
2383 error = do_lock_file_wait(filp, cmd, file_lock);
2386 * Attempt to detect a close/fcntl race and recover by releasing the
2387 * lock that was just acquired. There is no need to do that when we're
2388 * unlocking though, or for OFD locks.
2390 if (!error && file_lock->fl_type != F_UNLCK &&
2391 !(file_lock->fl_flags & FL_OFDLCK)) {
2392 struct files_struct *files = current->files;
2394 * We need that spin_lock here - it prevents reordering between
2395 * update of i_flctx->flc_posix and check for it done in
2396 * close(). rcu_read_lock() wouldn't do.
2398 spin_lock(&files->file_lock);
2399 f = files_lookup_fd_locked(files, fd);
2400 spin_unlock(&files->file_lock);
2402 file_lock->fl_type = F_UNLCK;
2403 error = do_lock_file_wait(filp, cmd, file_lock);
2404 WARN_ON_ONCE(error);
2409 trace_fcntl_setlk(inode, file_lock, error);
2410 locks_free_lock(file_lock);
2414 #if BITS_PER_LONG == 32
2415 /* Report the first existing lock that would conflict with l.
2416 * This implements the F_GETLK command of fcntl().
2418 int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2420 struct file_lock *fl;
2423 fl = locks_alloc_lock();
2428 if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2429 && flock->l_type != F_WRLCK)
2432 error = flock64_to_posix_lock(filp, fl, flock);
2436 if (cmd == F_OFD_GETLK) {
2438 if (flock->l_pid != 0)
2441 fl->fl_flags |= FL_OFDLCK;
2442 fl->fl_owner = filp;
2445 error = vfs_test_lock(filp, fl);
2449 flock->l_type = fl->fl_type;
2450 if (fl->fl_type != F_UNLCK)
2451 posix_lock_to_flock64(flock, fl);
2454 locks_free_lock(fl);
2458 /* Apply the lock described by l to an open file descriptor.
2459 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2461 int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2462 struct flock64 *flock)
2464 struct file_lock *file_lock = locks_alloc_lock();
2468 if (file_lock == NULL)
2471 error = flock64_to_posix_lock(filp, file_lock, flock);
2475 error = check_fmode_for_setlk(file_lock);
2480 * If the cmd is requesting file-private locks, then set the
2481 * FL_OFDLCK flag and override the owner.
2486 if (flock->l_pid != 0)
2490 file_lock->fl_flags |= FL_OFDLCK;
2491 file_lock->fl_owner = filp;
2495 if (flock->l_pid != 0)
2499 file_lock->fl_flags |= FL_OFDLCK;
2500 file_lock->fl_owner = filp;
2503 file_lock->fl_flags |= FL_SLEEP;
2506 error = do_lock_file_wait(filp, cmd, file_lock);
2509 * Attempt to detect a close/fcntl race and recover by releasing the
2510 * lock that was just acquired. There is no need to do that when we're
2511 * unlocking though, or for OFD locks.
2513 if (!error && file_lock->fl_type != F_UNLCK &&
2514 !(file_lock->fl_flags & FL_OFDLCK)) {
2515 struct files_struct *files = current->files;
2517 * We need that spin_lock here - it prevents reordering between
2518 * update of i_flctx->flc_posix and check for it done in
2519 * close(). rcu_read_lock() wouldn't do.
2521 spin_lock(&files->file_lock);
2522 f = files_lookup_fd_locked(files, fd);
2523 spin_unlock(&files->file_lock);
2525 file_lock->fl_type = F_UNLCK;
2526 error = do_lock_file_wait(filp, cmd, file_lock);
2527 WARN_ON_ONCE(error);
2532 locks_free_lock(file_lock);
2535 #endif /* BITS_PER_LONG == 32 */
2538 * This function is called when the file is being removed
2539 * from the task's fd array. POSIX locks belonging to this task
2540 * are deleted at this time.
2542 void locks_remove_posix(struct file *filp, fl_owner_t owner)
2545 struct inode *inode = file_inode(filp);
2546 struct file_lock lock;
2547 struct file_lock_context *ctx;
2550 * If there are no locks held on this file, we don't need to call
2551 * posix_lock_file(). Another process could be setting a lock on this
2552 * file at the same time, but we wouldn't remove that lock anyway.
2554 ctx = locks_inode_context(inode);
2555 if (!ctx || list_empty(&ctx->flc_posix))
2558 locks_init_lock(&lock);
2559 lock.fl_type = F_UNLCK;
2560 lock.fl_flags = FL_POSIX | FL_CLOSE;
2562 lock.fl_end = OFFSET_MAX;
2563 lock.fl_owner = owner;
2564 lock.fl_pid = current->tgid;
2565 lock.fl_file = filp;
2567 lock.fl_lmops = NULL;
2569 error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2571 if (lock.fl_ops && lock.fl_ops->fl_release_private)
2572 lock.fl_ops->fl_release_private(&lock);
2573 trace_locks_remove_posix(inode, &lock, error);
2575 EXPORT_SYMBOL(locks_remove_posix);
2577 /* The i_flctx must be valid when calling into here */
2579 locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2581 struct file_lock fl;
2582 struct inode *inode = file_inode(filp);
2584 if (list_empty(&flctx->flc_flock))
2587 flock_make_lock(filp, &fl, F_UNLCK);
2588 fl.fl_flags |= FL_CLOSE;
2590 if (filp->f_op->flock)
2591 filp->f_op->flock(filp, F_SETLKW, &fl);
2593 flock_lock_inode(inode, &fl);
2595 if (fl.fl_ops && fl.fl_ops->fl_release_private)
2596 fl.fl_ops->fl_release_private(&fl);
2599 /* The i_flctx must be valid when calling into here */
2601 locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2603 struct file_lock *fl, *tmp;
2606 if (list_empty(&ctx->flc_lease))
2609 percpu_down_read(&file_rwsem);
2610 spin_lock(&ctx->flc_lock);
2611 list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2612 if (filp == fl->fl_file)
2613 lease_modify(fl, F_UNLCK, &dispose);
2614 spin_unlock(&ctx->flc_lock);
2615 percpu_up_read(&file_rwsem);
2617 locks_dispose_list(&dispose);
2621 * This function is called on the last close of an open file.
2623 void locks_remove_file(struct file *filp)
2625 struct file_lock_context *ctx;
2627 ctx = locks_inode_context(file_inode(filp));
2631 /* remove any OFD locks */
2632 locks_remove_posix(filp, filp);
2634 /* remove flock locks */
2635 locks_remove_flock(filp, ctx);
2637 /* remove any leases */
2638 locks_remove_lease(filp, ctx);
2640 spin_lock(&ctx->flc_lock);
2641 locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2642 locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2643 locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2644 spin_unlock(&ctx->flc_lock);
2648 * vfs_cancel_lock - file byte range unblock lock
2649 * @filp: The file to apply the unblock to
2650 * @fl: The lock to be unblocked
2652 * Used by lock managers to cancel blocked requests
2654 int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2656 WARN_ON_ONCE(filp != fl->fl_file);
2657 if (filp->f_op->lock)
2658 return filp->f_op->lock(filp, F_CANCELLK, fl);
2661 EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2664 * vfs_inode_has_locks - are any file locks held on @inode?
2665 * @inode: inode to check for locks
2667 * Return true if there are any FL_POSIX or FL_FLOCK locks currently
2670 bool vfs_inode_has_locks(struct inode *inode)
2672 struct file_lock_context *ctx;
2675 ctx = locks_inode_context(inode);
2679 spin_lock(&ctx->flc_lock);
2680 ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
2681 spin_unlock(&ctx->flc_lock);
2684 EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
2686 #ifdef CONFIG_PROC_FS
2687 #include <linux/proc_fs.h>
2688 #include <linux/seq_file.h>
2690 struct locks_iterator {
2695 static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2696 loff_t id, char *pfx, int repeat)
2698 struct inode *inode = NULL;
2699 unsigned int fl_pid;
2700 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2703 fl_pid = locks_translate_pid(fl, proc_pidns);
2705 * If lock owner is dead (and pid is freed) or not visible in current
2706 * pidns, zero is shown as a pid value. Check lock info from
2707 * init_pid_ns to get saved lock pid value.
2710 if (fl->fl_file != NULL)
2711 inode = file_inode(fl->fl_file);
2713 seq_printf(f, "%lld: ", id);
2716 seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
2719 if (fl->fl_flags & FL_ACCESS)
2720 seq_puts(f, "ACCESS");
2721 else if (IS_OFDLCK(fl))
2722 seq_puts(f, "OFDLCK");
2724 seq_puts(f, "POSIX ");
2726 seq_printf(f, " %s ",
2727 (inode == NULL) ? "*NOINODE*" : "ADVISORY ");
2728 } else if (IS_FLOCK(fl)) {
2729 seq_puts(f, "FLOCK ADVISORY ");
2730 } else if (IS_LEASE(fl)) {
2731 if (fl->fl_flags & FL_DELEG)
2732 seq_puts(f, "DELEG ");
2734 seq_puts(f, "LEASE ");
2736 if (lease_breaking(fl))
2737 seq_puts(f, "BREAKING ");
2738 else if (fl->fl_file)
2739 seq_puts(f, "ACTIVE ");
2741 seq_puts(f, "BREAKER ");
2743 seq_puts(f, "UNKNOWN UNKNOWN ");
2745 type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
2747 seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2748 (type == F_RDLCK) ? "READ" : "UNLCK");
2750 /* userspace relies on this representation of dev_t */
2751 seq_printf(f, "%d %02x:%02x:%lu ", fl_pid,
2752 MAJOR(inode->i_sb->s_dev),
2753 MINOR(inode->i_sb->s_dev), inode->i_ino);
2755 seq_printf(f, "%d <none>:0 ", fl_pid);
2758 if (fl->fl_end == OFFSET_MAX)
2759 seq_printf(f, "%Ld EOF\n", fl->fl_start);
2761 seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2763 seq_puts(f, "0 EOF\n");
2767 static struct file_lock *get_next_blocked_member(struct file_lock *node)
2769 struct file_lock *tmp;
2771 /* NULL node or root node */
2772 if (node == NULL || node->fl_blocker == NULL)
2775 /* Next member in the linked list could be itself */
2776 tmp = list_next_entry(node, fl_blocked_member);
2777 if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member)
2785 static int locks_show(struct seq_file *f, void *v)
2787 struct locks_iterator *iter = f->private;
2788 struct file_lock *cur, *tmp;
2789 struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2792 cur = hlist_entry(v, struct file_lock, fl_link);
2794 if (locks_translate_pid(cur, proc_pidns) == 0)
2797 /* View this crossed linked list as a binary tree, the first member of fl_blocked_requests
2798 * is the left child of current node, the next silibing in fl_blocked_member is the
2799 * right child, we can alse get the parent of current node from fl_blocker, so this
2800 * question becomes traversal of a binary tree
2802 while (cur != NULL) {
2804 lock_get_status(f, cur, iter->li_pos, "-> ", level);
2806 lock_get_status(f, cur, iter->li_pos, "", level);
2808 if (!list_empty(&cur->fl_blocked_requests)) {
2810 cur = list_first_entry_or_null(&cur->fl_blocked_requests,
2811 struct file_lock, fl_blocked_member);
2815 tmp = get_next_blocked_member(cur);
2816 /* Fall back to parent node */
2817 while (tmp == NULL && cur->fl_blocker != NULL) {
2818 cur = cur->fl_blocker;
2820 tmp = get_next_blocked_member(cur);
2829 static void __show_fd_locks(struct seq_file *f,
2830 struct list_head *head, int *id,
2831 struct file *filp, struct files_struct *files)
2833 struct file_lock *fl;
2835 list_for_each_entry(fl, head, fl_list) {
2837 if (filp != fl->fl_file)
2839 if (fl->fl_owner != files &&
2840 fl->fl_owner != filp)
2844 seq_puts(f, "lock:\t");
2845 lock_get_status(f, fl, *id, "", 0);
2849 void show_fd_locks(struct seq_file *f,
2850 struct file *filp, struct files_struct *files)
2852 struct inode *inode = file_inode(filp);
2853 struct file_lock_context *ctx;
2856 ctx = locks_inode_context(inode);
2860 spin_lock(&ctx->flc_lock);
2861 __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2862 __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2863 __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2864 spin_unlock(&ctx->flc_lock);
2867 static void *locks_start(struct seq_file *f, loff_t *pos)
2868 __acquires(&blocked_lock_lock)
2870 struct locks_iterator *iter = f->private;
2872 iter->li_pos = *pos + 1;
2873 percpu_down_write(&file_rwsem);
2874 spin_lock(&blocked_lock_lock);
2875 return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2878 static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2880 struct locks_iterator *iter = f->private;
2883 return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2886 static void locks_stop(struct seq_file *f, void *v)
2887 __releases(&blocked_lock_lock)
2889 spin_unlock(&blocked_lock_lock);
2890 percpu_up_write(&file_rwsem);
2893 static const struct seq_operations locks_seq_operations = {
2894 .start = locks_start,
2900 static int __init proc_locks_init(void)
2902 proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
2903 sizeof(struct locks_iterator), NULL);
2906 fs_initcall(proc_locks_init);
2909 static int __init filelock_init(void)
2913 flctx_cache = kmem_cache_create("file_lock_ctx",
2914 sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2916 filelock_cache = kmem_cache_create("file_lock_cache",
2917 sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2919 for_each_possible_cpu(i) {
2920 struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
2922 spin_lock_init(&fll->lock);
2923 INIT_HLIST_HEAD(&fll->hlist);
2926 lease_notifier_chain_init();
2929 core_initcall(filelock_init);