2 * Copyright (C) 2018-2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
4 * SPDX-License-Identifier: GPL-2.0-only
10 #include <urcu/rculfhash.h>
17 #include <sys/types.h>
19 #include <common/defaults.hpp>
20 #include <common/error.hpp>
21 #include <common/fs-handle-internal.hpp>
22 #include <common/hashtable/hashtable.hpp>
23 #include <common/hashtable/utils.hpp>
24 #include <common/macros.hpp>
25 #include <common/optional.hpp>
27 #include "fd-tracker.hpp"
30 /* Tracker lock must be taken by the user. */
31 #define TRACKED_COUNT(tracker) \
32 (tracker->count.suspendable.active + \
33 tracker->count.suspendable.suspended + \
34 tracker->count.unsuspendable)
36 /* Tracker lock must be taken by the user. */
37 #define ACTIVE_COUNT(tracker) \
38 (tracker->count.suspendable.active + tracker->count.unsuspendable)
40 /* Tracker lock must be taken by the user. */
41 #define SUSPENDED_COUNT(tracker) (tracker->count.suspendable.suspended)
43 /* Tracker lock must be taken by the user. */
44 #define SUSPENDABLE_COUNT(tracker) \
45 (tracker->count.suspendable.active + \
46 tracker->count.suspendable.suspended)
48 /* Tracker lock must be taken by the user. */
49 #define UNSUSPENDABLE_COUNT(tracker) (tracker->count.unsuspendable)
56 unsigned int suspended
;
58 unsigned int unsuspendable
;
60 unsigned int capacity
;
64 /* Failures to suspend or restore fs handles. */
68 * The head of the active_handles list is always the least recently
69 * used active handle. When an handle is used, it is removed from the
70 * list and added to the end. When a file has to be suspended, the
71 * first element in the list is "popped", suspended, and added to the
72 * list of suspended handles.
74 struct cds_list_head active_handles
;
75 struct cds_list_head suspended_handles
;
76 struct cds_lfht
*unsuspendable_fds
;
77 struct lttng_inode_registry
*inode_registry
;
78 /* Unlinked files are moved in this directory under a unique name. */
79 struct lttng_directory_handle
*unlink_directory_handle
;
80 struct lttng_unlinked_file_pool
*unlinked_file_pool
;
84 struct open_properties
{
86 LTTNG_OPTIONAL(mode_t
) mode
;
90 * A fs_handle_tracked is not ref-counted. Therefore, it is assumed that a
91 * handle is never in-use while it is being reclaimed. It can be
92 * shared by multiple threads, but external synchronization is required
93 * to ensure it is not still being used when it is reclaimed (close method).
94 * In this respect, it is not different from a regular file descriptor.
96 * The fs_handle lock always nests _within_ the tracker's lock.
98 struct fs_handle_tracked
{
99 struct fs_handle parent
;
100 pthread_mutex_t lock
;
102 * Weak reference to the tracker. All fs_handles are assumed to have
103 * been closed at the moment of the destruction of the fd_tracker.
105 struct fd_tracker
*tracker
;
106 struct open_properties properties
;
107 struct lttng_inode
*inode
;
109 /* inode number of the file at the time of the handle's creation. */
112 /* Offset to which the file should be restored. */
114 struct cds_list_head handles_list_node
;
117 struct unsuspendable_fd
{
119 * Accesses are only performed through the tracker, which is protected
124 struct cds_lfht_node tracker_node
;
125 struct rcu_head rcu_head
;
129 pthread_mutex_t lock
;
133 .lock
= PTHREAD_MUTEX_INITIALIZER
,
134 .initialized
= false,
139 static int match_fd(struct cds_lfht_node
*node
, const void *key
);
140 static void unsuspendable_fd_destroy(struct unsuspendable_fd
*entry
);
141 static struct unsuspendable_fd
*unsuspendable_fd_create(
142 const char *name
, int fd
);
143 static int open_from_properties(const struct lttng_directory_handle
*dir_handle
,
144 const char *path
, struct open_properties
*properties
);
146 static void fs_handle_tracked_log(struct fs_handle_tracked
*handle
);
147 static int fs_handle_tracked_suspend(struct fs_handle_tracked
*handle
);
148 static int fs_handle_tracked_restore(struct fs_handle_tracked
*handle
);
149 static int fs_handle_tracked_get_fd(struct fs_handle
*_handle
);
150 static void fs_handle_tracked_put_fd(struct fs_handle
*_handle
);
151 static int fs_handle_tracked_unlink(struct fs_handle
*_handle
);
152 static int fs_handle_tracked_close(struct fs_handle
*_handle
);
154 static void fd_tracker_track(
155 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
);
156 static void fd_tracker_untrack(
157 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
);
158 static int fd_tracker_suspend_handles(
159 struct fd_tracker
*tracker
, unsigned int count
);
160 static int fd_tracker_restore_handle(
161 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
);
163 /* Match function of the tracker's unsuspendable_fds hash table. */
164 static int match_fd(struct cds_lfht_node
*node
, const void *key
)
166 struct unsuspendable_fd
*entry
= lttng::utils::container_of(
167 node
, &unsuspendable_fd::tracker_node
);
169 return hash_match_key_ulong(
170 (void *) (unsigned long) entry
->fd
, (void *) key
);
173 static void delete_unsuspendable_fd(struct rcu_head
*head
)
175 struct unsuspendable_fd
*fd
= caa_container_of(
176 head
, struct unsuspendable_fd
, rcu_head
);
182 static void unsuspendable_fd_destroy(struct unsuspendable_fd
*entry
)
187 call_rcu(&entry
->rcu_head
, delete_unsuspendable_fd
);
190 static struct unsuspendable_fd
*unsuspendable_fd_create(
191 const char *name
, int fd
)
193 struct unsuspendable_fd
*entry
= zmalloc
<unsuspendable_fd
>();
199 entry
->name
= strdup(name
);
204 cds_lfht_node_init(&entry
->tracker_node
);
208 unsuspendable_fd_destroy(entry
);
212 static void fs_handle_tracked_log(struct fs_handle_tracked
*handle
)
216 pthread_mutex_lock(&handle
->lock
);
217 lttng_inode_borrow_location(handle
->inode
, NULL
, &path
);
219 if (handle
->fd
>= 0) {
220 DBG_NO_LOC(" %s [active, fd %d%s]", path
, handle
->fd
,
221 handle
->in_use
? ", in use" : "");
223 DBG_NO_LOC(" %s [suspended]", path
);
225 pthread_mutex_unlock(&handle
->lock
);
228 /* Tracker lock must be held by the caller. */
229 static int fs_handle_tracked_suspend(struct fs_handle_tracked
*handle
)
234 const struct lttng_directory_handle
*node_directory_handle
;
236 pthread_mutex_lock(&handle
->lock
);
237 lttng_inode_borrow_location(
238 handle
->inode
, &node_directory_handle
, &path
);
239 LTTNG_ASSERT(handle
->fd
>= 0);
240 if (handle
->in_use
) {
241 /* This handle can't be suspended as it is currently in use. */
246 ret
= lttng_directory_handle_stat(
247 node_directory_handle
, path
, &fs_stat
);
249 PERROR("Filesystem handle to %s cannot be suspended as stat() failed",
255 if (fs_stat
.st_ino
!= handle
->ino
) {
256 /* Don't suspend as the handle would not be restorable. */
257 WARN("Filesystem handle to %s cannot be suspended as its inode changed",
263 handle
->offset
= lseek(handle
->fd
, 0, SEEK_CUR
);
264 if (handle
->offset
== -1) {
265 WARN("Filesystem handle to %s cannot be suspended as lseek() failed to sample its current position",
271 ret
= close(handle
->fd
);
273 PERROR("Filesystem handle to %s cannot be suspended as close() failed",
278 DBG("Suspended filesystem handle to %s (fd %i) at position %" PRId64
,
279 path
, handle
->fd
, handle
->offset
);
283 handle
->tracker
->stats
.errors
++;
285 pthread_mutex_unlock(&handle
->lock
);
289 /* Caller must hold the tracker and handle's locks. */
290 static int fs_handle_tracked_restore(struct fs_handle_tracked
*handle
)
294 const struct lttng_directory_handle
*node_directory_handle
;
296 lttng_inode_borrow_location(
297 handle
->inode
, &node_directory_handle
, &path
);
299 LTTNG_ASSERT(handle
->fd
== -1);
301 ret
= open_from_properties(
302 node_directory_handle
, path
, &handle
->properties
);
304 PERROR("Failed to restore filesystem handle to %s, open() failed",
311 ret
= lseek(fd
, handle
->offset
, SEEK_SET
);
313 PERROR("Failed to restore filesystem handle to %s, lseek() failed",
318 DBG("Restored filesystem handle to %s (fd %i) at position %" PRId64
,
319 path
, fd
, handle
->offset
);
330 static int open_from_properties(const struct lttng_directory_handle
*dir_handle
,
331 const char *path
, struct open_properties
*properties
)
336 * open() ignores the 'flags' parameter unless the O_CREAT or O_TMPFILE
337 * flags are set. O_TMPFILE would not make sense in the context of a
338 * suspendable fs_handle as it would not be restorable (see OPEN(2)),
339 * thus it is ignored here.
341 if ((properties
->flags
& O_CREAT
) && properties
->mode
.is_set
) {
342 ret
= lttng_directory_handle_open_file(dir_handle
, path
,
343 properties
->flags
, properties
->mode
.value
);
345 ret
= lttng_directory_handle_open_file(dir_handle
, path
,
346 properties
->flags
, 0);
349 * Some flags should not be used beyond the initial open() of a
350 * restorable file system handle. O_CREAT and O_TRUNC must
351 * be cleared since it would be unexpected to re-use them
352 * when the handle is retored:
353 * - O_CREAT should not be needed as the file has been created
354 * on the initial call to open(),
355 * - O_TRUNC would destroy the file's contents by truncating it
358 properties
->flags
&= ~(O_CREAT
| O_TRUNC
);
367 struct fd_tracker
*fd_tracker_create(const char *unlinked_file_path
,
368 unsigned int capacity
)
370 struct fd_tracker
*tracker
= zmalloc
<fd_tracker
>();
376 pthread_mutex_lock(&seed
.lock
);
377 if (!seed
.initialized
) {
378 seed
.value
= (unsigned long) time(NULL
);
379 seed
.initialized
= true;
381 pthread_mutex_unlock(&seed
.lock
);
383 CDS_INIT_LIST_HEAD(&tracker
->active_handles
);
384 CDS_INIT_LIST_HEAD(&tracker
->suspended_handles
);
385 tracker
->capacity
= capacity
;
386 tracker
->unsuspendable_fds
= cds_lfht_new(DEFAULT_HT_SIZE
, 1, 0,
387 CDS_LFHT_AUTO_RESIZE
| CDS_LFHT_ACCOUNTING
, NULL
);
388 if (!tracker
->unsuspendable_fds
) {
389 ERR("Failed to create fd-tracker's unsuspendable_fds hash table");
392 tracker
->inode_registry
= lttng_inode_registry_create();
393 if (!tracker
->inode_registry
) {
394 ERR("Failed to create fd-tracker's inode registry");
398 tracker
->unlinked_file_pool
=
399 lttng_unlinked_file_pool_create(unlinked_file_path
);
400 if (!tracker
->unlinked_file_pool
) {
403 DBG("File descriptor tracker created with a limit of %u simultaneously-opened FDs",
408 fd_tracker_destroy(tracker
);
412 void fd_tracker_log(struct fd_tracker
*tracker
)
414 struct fs_handle_tracked
*handle
;
415 struct unsuspendable_fd
*unsuspendable_fd
;
416 struct cds_lfht_iter iter
;
418 pthread_mutex_lock(&tracker
->lock
);
419 DBG_NO_LOC("File descriptor tracker");
420 DBG_NO_LOC(" Stats:");
421 DBG_NO_LOC(" uses: %" PRIu64
, tracker
->stats
.uses
);
422 DBG_NO_LOC(" misses: %" PRIu64
, tracker
->stats
.misses
);
423 DBG_NO_LOC(" errors: %" PRIu64
, tracker
->stats
.errors
);
424 DBG_NO_LOC(" Tracked: %u", TRACKED_COUNT(tracker
));
425 DBG_NO_LOC(" active: %u", ACTIVE_COUNT(tracker
));
426 DBG_NO_LOC(" suspendable: %u", SUSPENDABLE_COUNT(tracker
));
427 DBG_NO_LOC(" unsuspendable: %u", UNSUSPENDABLE_COUNT(tracker
));
428 DBG_NO_LOC(" suspended: %u", SUSPENDED_COUNT(tracker
));
429 DBG_NO_LOC(" capacity: %u", tracker
->capacity
);
431 DBG_NO_LOC(" Tracked suspendable file descriptors");
432 cds_list_for_each_entry(
433 handle
, &tracker
->active_handles
, handles_list_node
) {
434 fs_handle_tracked_log(handle
);
436 cds_list_for_each_entry(handle
, &tracker
->suspended_handles
,
438 fs_handle_tracked_log(handle
);
440 if (!SUSPENDABLE_COUNT(tracker
)) {
444 DBG_NO_LOC(" Tracked unsuspendable file descriptors");
446 cds_lfht_for_each_entry(tracker
->unsuspendable_fds
, &iter
,
447 unsuspendable_fd
, tracker_node
) {
448 DBG_NO_LOC(" %s [active, fd %d]",
449 unsuspendable_fd
->name
?: "Unnamed",
450 unsuspendable_fd
->fd
);
453 if (!UNSUSPENDABLE_COUNT(tracker
)) {
457 pthread_mutex_unlock(&tracker
->lock
);
460 int fd_tracker_destroy(struct fd_tracker
*tracker
)
468 * Refuse to destroy the tracker as fs_handles may still old
469 * weak references to the tracker.
471 pthread_mutex_lock(&tracker
->lock
);
472 if (TRACKED_COUNT(tracker
)) {
473 ERR("A file descriptor leak has been detected: %u tracked file descriptors are still being tracked",
474 TRACKED_COUNT(tracker
));
475 pthread_mutex_unlock(&tracker
->lock
);
476 fd_tracker_log(tracker
);
480 pthread_mutex_unlock(&tracker
->lock
);
482 if (tracker
->unsuspendable_fds
) {
483 ret
= cds_lfht_destroy(tracker
->unsuspendable_fds
, NULL
);
487 lttng_inode_registry_destroy(tracker
->inode_registry
);
488 lttng_unlinked_file_pool_destroy(tracker
->unlinked_file_pool
);
489 pthread_mutex_destroy(&tracker
->lock
);
495 struct fs_handle
*fd_tracker_open_fs_handle(struct fd_tracker
*tracker
,
496 struct lttng_directory_handle
*directory
,
502 struct fs_handle_tracked
*handle
= NULL
;
504 struct open_properties properties
= {
508 .value
= static_cast<mode_t
>(mode
? *mode
: 0),
512 pthread_mutex_lock(&tracker
->lock
);
513 if (ACTIVE_COUNT(tracker
) == tracker
->capacity
) {
514 if (tracker
->count
.suspendable
.active
> 0) {
515 ret
= fd_tracker_suspend_handles(tracker
, 1);
521 * There are not enough active suspendable file
522 * descriptors to open a new fd and still accommodate
523 * the tracker's capacity.
525 WARN("Cannot open file system handle, too many unsuspendable file descriptors are opened (%u)",
526 tracker
->count
.unsuspendable
);
531 handle
= zmalloc
<fs_handle_tracked
>();
535 handle
->parent
= (typeof(handle
->parent
)) {
536 .get_fd
= fs_handle_tracked_get_fd
,
537 .put_fd
= fs_handle_tracked_put_fd
,
538 .unlink
= fs_handle_tracked_unlink
,
539 .close
= fs_handle_tracked_close
,
542 handle
->tracker
= tracker
;
544 ret
= pthread_mutex_init(&handle
->lock
, NULL
);
546 PERROR("Failed to initialize handle mutex while creating fs handle");
547 goto error_mutex_init
;
550 handle
->fd
= open_from_properties(directory
, path
, &properties
);
551 if (handle
->fd
< 0) {
552 PERROR("Failed to open fs handle to %s, open() returned", path
);
556 handle
->properties
= properties
;
558 handle
->inode
= lttng_inode_registry_get_inode(tracker
->inode_registry
,
559 directory
, path
, handle
->fd
,
560 tracker
->unlinked_file_pool
);
561 if (!handle
->inode
) {
562 ERR("Failed to get lttng_inode corresponding to file %s", path
);
566 if (fstat(handle
->fd
, &fd_stat
)) {
567 PERROR("Failed to retrieve file descriptor inode while creating fs handle, fstat() returned");
570 handle
->ino
= fd_stat
.st_ino
;
572 fd_tracker_track(tracker
, handle
);
574 pthread_mutex_unlock(&tracker
->lock
);
575 return handle
? &handle
->parent
: NULL
;
578 lttng_inode_put(handle
->inode
);
580 pthread_mutex_destroy(&handle
->lock
);
587 /* Caller must hold the tracker's lock. */
588 static int fd_tracker_suspend_handles(
589 struct fd_tracker
*tracker
, unsigned int count
)
591 unsigned int left_to_close
= count
;
592 unsigned int attempts_left
= tracker
->count
.suspendable
.active
;
593 struct fs_handle_tracked
*handle
, *tmp
;
595 cds_list_for_each_entry_safe(handle
, tmp
, &tracker
->active_handles
,
599 fd_tracker_untrack(tracker
, handle
);
600 ret
= fs_handle_tracked_suspend(handle
);
601 fd_tracker_track(tracker
, handle
);
607 if (left_to_close
== 0 || attempts_left
== 0) {
611 return left_to_close
? -EMFILE
: 0;
614 int fd_tracker_open_unsuspendable_fd(struct fd_tracker
*tracker
,
617 unsigned int fd_count
,
621 int ret
, user_ret
, i
, fds_to_suspend
;
622 unsigned int active_fds
;
623 struct unsuspendable_fd
**entries
;
625 entries
= calloc
<unsuspendable_fd
*>(fd_count
);
631 pthread_mutex_lock(&tracker
->lock
);
633 active_fds
= ACTIVE_COUNT(tracker
);
634 fds_to_suspend
= (int) active_fds
+ (int) fd_count
-
635 (int) tracker
->capacity
;
636 if (fds_to_suspend
> 0) {
637 if (fds_to_suspend
<= tracker
->count
.suspendable
.active
) {
638 ret
= fd_tracker_suspend_handles(
639 tracker
, fds_to_suspend
);
645 * There are not enough active suspendable file
646 * descriptors to open a new fd and still accommodates the
647 * tracker's capacity.
649 WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)",
650 tracker
->count
.unsuspendable
);
656 user_ret
= open(user_data
, out_fds
);
663 * Add the fds returned by the user's callback to the hashtable
664 * of unsuspendable fds.
666 for (i
= 0; i
< fd_count
; i
++) {
667 struct unsuspendable_fd
*entry
= unsuspendable_fd_create(
668 names
? names
[i
] : NULL
, out_fds
[i
]);
672 goto end_free_entries
;
678 for (i
= 0; i
< fd_count
; i
++) {
679 struct cds_lfht_node
*node
;
680 struct unsuspendable_fd
*entry
= entries
[i
];
682 node
= cds_lfht_add_unique(tracker
->unsuspendable_fds
,
683 hash_key_ulong((void *) (unsigned long)
686 match_fd
, (void *) (unsigned long) out_fds
[i
],
687 &entry
->tracker_node
);
689 if (node
!= &entry
->tracker_node
) {
692 goto end_free_entries
;
696 tracker
->count
.unsuspendable
+= fd_count
;
700 pthread_mutex_unlock(&tracker
->lock
);
705 for (i
= 0; i
< fd_count
; i
++) {
706 unsuspendable_fd_destroy(entries
[i
]);
711 int fd_tracker_close_unsuspendable_fd(struct fd_tracker
*tracker
,
713 unsigned int fd_count
,
717 int i
, ret
, user_ret
;
721 * Maintain a local copy of fds_in as the user's callback may modify its
722 * contents (e.g. setting the fd(s) to -1 after close).
724 fds
= malloc
<int>(sizeof(*fds
) * fd_count
);
729 memcpy(fds
, fds_in
, sizeof(*fds
) * fd_count
);
731 pthread_mutex_lock(&tracker
->lock
);
734 /* Let the user close the file descriptors. */
735 user_ret
= close(user_data
, fds_in
);
741 /* Untrack the fds that were just closed by the user's callback. */
742 for (i
= 0; i
< fd_count
; i
++) {
743 struct cds_lfht_node
*node
;
744 struct cds_lfht_iter iter
;
745 struct unsuspendable_fd
*entry
;
747 cds_lfht_lookup(tracker
->unsuspendable_fds
,
748 hash_key_ulong((void *) (unsigned long) fds
[i
],
750 match_fd
, (void *) (unsigned long) fds
[i
],
752 node
= cds_lfht_iter_get_node(&iter
);
754 /* Unknown file descriptor. */
755 WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()",
760 entry
= lttng::utils::container_of(
761 node
, &unsuspendable_fd::tracker_node
);
763 cds_lfht_del(tracker
->unsuspendable_fds
, node
);
764 unsuspendable_fd_destroy(entry
);
768 tracker
->count
.unsuspendable
-= fd_count
;
772 pthread_mutex_unlock(&tracker
->lock
);
778 /* Caller must have taken the tracker's and handle's locks. */
779 static void fd_tracker_track(
780 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
)
782 if (handle
->fd
>= 0) {
783 tracker
->count
.suspendable
.active
++;
784 cds_list_add_tail(&handle
->handles_list_node
,
785 &tracker
->active_handles
);
787 tracker
->count
.suspendable
.suspended
++;
788 cds_list_add_tail(&handle
->handles_list_node
,
789 &tracker
->suspended_handles
);
793 /* Caller must have taken the tracker's and handle's locks. */
794 static void fd_tracker_untrack(
795 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
)
797 if (handle
->fd
>= 0) {
798 tracker
->count
.suspendable
.active
--;
800 tracker
->count
.suspendable
.suspended
--;
802 cds_list_del(&handle
->handles_list_node
);
805 /* Caller must have taken the tracker's and handle's locks. */
806 static int fd_tracker_restore_handle(
807 struct fd_tracker
*tracker
, struct fs_handle_tracked
*handle
)
811 fd_tracker_untrack(tracker
, handle
);
812 if (ACTIVE_COUNT(tracker
) >= tracker
->capacity
) {
813 ret
= fd_tracker_suspend_handles(tracker
, 1);
818 ret
= fs_handle_tracked_restore(handle
);
820 fd_tracker_track(tracker
, handle
);
821 return ret
? ret
: handle
->fd
;
824 static int fs_handle_tracked_get_fd(struct fs_handle
*_handle
)
827 struct fs_handle_tracked
*handle
=
828 lttng::utils::container_of(_handle
, &fs_handle_tracked::parent
);
831 * TODO This should be optimized as it is a fairly hot path.
832 * The fd-tracker's lock should only be taken when a fs_handle is
833 * restored (slow path). On the fast path (fs_handle is active),
834 * the only effect on the fd_tracker is marking the handle as the
835 * most recently used. Currently, it is done by a call to the
836 * track/untrack helpers, but it should be done atomically.
838 * Note that the lock's nesting order must still be respected here.
839 * The handle's lock nests inside the tracker's lock.
841 pthread_mutex_lock(&handle
->tracker
->lock
);
842 pthread_mutex_lock(&handle
->lock
);
843 LTTNG_ASSERT(!handle
->in_use
);
845 handle
->tracker
->stats
.uses
++;
846 if (handle
->fd
>= 0) {
848 /* Mark as most recently used. */
849 fd_tracker_untrack(handle
->tracker
, handle
);
850 fd_tracker_track(handle
->tracker
, handle
);
852 handle
->tracker
->stats
.misses
++;
853 ret
= fd_tracker_restore_handle(handle
->tracker
, handle
);
855 handle
->tracker
->stats
.errors
++;
859 handle
->in_use
= true;
861 pthread_mutex_unlock(&handle
->lock
);
862 pthread_mutex_unlock(&handle
->tracker
->lock
);
866 static void fs_handle_tracked_put_fd(struct fs_handle
*_handle
)
868 struct fs_handle_tracked
*handle
=
869 lttng::utils::container_of(_handle
, &fs_handle_tracked::parent
);
871 pthread_mutex_lock(&handle
->lock
);
872 handle
->in_use
= false;
873 pthread_mutex_unlock(&handle
->lock
);
876 static int fs_handle_tracked_unlink(struct fs_handle
*_handle
)
879 struct fs_handle_tracked
*handle
=
880 lttng::utils::container_of(_handle
, &fs_handle_tracked::parent
);
882 pthread_mutex_lock(&handle
->tracker
->lock
);
883 pthread_mutex_lock(&handle
->lock
);
884 ret
= lttng_inode_unlink(handle
->inode
);
885 pthread_mutex_unlock(&handle
->lock
);
886 pthread_mutex_unlock(&handle
->tracker
->lock
);
890 static int fs_handle_tracked_close(struct fs_handle
*_handle
)
893 const char *path
= NULL
;
894 struct fs_handle_tracked
*handle
=
895 lttng::utils::container_of(_handle
, &fs_handle_tracked::parent
);
896 struct lttng_directory_handle
*inode_directory_handle
= NULL
;
903 pthread_mutex_lock(&handle
->tracker
->lock
);
904 pthread_mutex_lock(&handle
->lock
);
906 lttng_inode_borrow_location(handle
->inode
, NULL
, &path
);
908 * Here a reference to the inode's directory handle is acquired
909 * to prevent the last reference to it from being released while
910 * the tracker's lock is taken.
912 * If this wasn't done, the directory handle could attempt to
913 * close its underlying directory file descriptor, which would
914 * attempt to lock the tracker's lock, resulting in a deadlock.
916 * Since a new reference to the directory handle is taken within
917 * the scope of this function, it is not possible for the last
918 * reference to the inode's location directory handle to be
919 * released during the call to lttng_inode_put().
921 * We wait until the tracker's lock is released to release the
922 * reference. Hence, the call to the tracker is delayed just
923 * enough to not attempt to recursively acquire the tracker's
926 inode_directory_handle
=
927 lttng_inode_get_location_directory_handle(
930 fd_tracker_untrack(handle
->tracker
, handle
);
931 if (handle
->fd
>= 0) {
933 * The return value of close() is not propagated as there
934 * isn't much the user can do about it.
936 if (close(handle
->fd
)) {
937 PERROR("Failed to close the file descriptor (%d) of fs handle to %s, close() returned",
938 handle
->fd
, path
? path
: "Unknown");
943 lttng_inode_put(handle
->inode
);
945 pthread_mutex_unlock(&handle
->lock
);
946 pthread_mutex_destroy(&handle
->lock
);
947 pthread_mutex_unlock(&handle
->tracker
->lock
);
949 lttng_directory_handle_put(inode_directory_handle
);