fd-tracker: remove unneeded header inclusion
[lttng-tools.git] / src / common / fd-tracker / fd-tracker.c
CommitLineData
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1/*
2 * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License, version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 51
15 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
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18#include <urcu.h>
19#include <urcu/list.h>
20#include <urcu/rculfhash.h>
21
22#include <sys/stat.h>
23#include <sys/types.h>
24#include <fcntl.h>
25#include <stdbool.h>
26#include <pthread.h>
27#include <inttypes.h>
28
29#include "common/macros.h"
30#include "common/error.h"
31#include "common/defaults.h"
32#include "common/hashtable/utils.h"
33#include "common/hashtable/hashtable.h"
34
35#include "fd-tracker.h"
36
37/* Tracker lock must be taken by the user. */
38#define TRACKED_COUNT(tracker) \
39 (tracker->count.suspendable.active + \
40 tracker->count.suspendable.suspended + \
41 tracker->count.unsuspendable)
42
43/* Tracker lock must be taken by the user. */
44#define ACTIVE_COUNT(tracker) \
45 (tracker->count.suspendable.active + \
46 tracker->count.unsuspendable)
47
48/* Tracker lock must be taken by the user. */
49#define SUSPENDED_COUNT(tracker) \
50 (tracker->count.suspendable.suspended)
51
52/* Tracker lock must be taken by the user. */
53#define SUSPENDABLE_COUNT(tracker) \
54 (tracker->count.suspendable.active + \
55 tracker->count.suspendable.suspended)
56
57/* Tracker lock must be taken by the user. */
58#define UNSUSPENDABLE_COUNT(tracker) \
59 (tracker->count.unsuspendable)
60
61struct fd_tracker {
62 pthread_mutex_t lock;
63 struct {
64 struct {
65 unsigned int active;
66 unsigned int suspended;
67 } suspendable;
68 unsigned int unsuspendable;
69 } count;
70 unsigned int capacity;
71 struct {
72 uint64_t uses;
73 uint64_t misses;
74 /* Failures to suspend or restore fs handles. */
75 uint64_t errors;
76 } stats;
77 /*
78 * The head of the active_handles list is always the least recently
79 * used active handle. When an handle is used, it is removed from the
80 * list and added to the end. When a file has to be suspended, the
81 * first element in the list is "popped", suspended, and added to the
82 * list of suspended handles.
83 */
84 struct cds_list_head active_handles;
85 struct cds_list_head suspended_handles;
86 struct cds_lfht *unsuspendable_fds;
87};
88
89struct open_properties {
90 char *path;
91 int flags;
92 struct {
93 bool is_set;
94 mode_t value;
95 } mode;
96};
97
98/*
99 * A fs_handle is not ref-counted. Therefore, it is assumed that a
100 * handle is never in-use while it is being reclaimed. It can be
101 * shared by multiple threads, but external synchronization is required
102 * to ensure it is not still being used when it is reclaimed (close method).
103 * In this respect, it is not different from a regular file descriptor.
104 *
105 * The fs_handle lock always nests _within_ the tracker's lock.
106 */
107struct fs_handle {
108 pthread_mutex_t lock;
109 /*
110 * Weak reference to the tracker. All fs_handles are assumed to have
111 * been closed at the moment of the destruction of the fd_tracker.
112 */
113 struct fd_tracker *tracker;
114 struct open_properties properties;
115 int fd;
116 /* inode number of the file at the time of the handle's creation. */
117 uint64_t ino;
118 bool in_use;
119 /* Offset to which the file should be restored. */
120 off_t offset;
121 struct cds_list_head handles_list_node;
122};
123
124struct unsuspendable_fd {
125 /*
126 * Accesses are only performed through the tracker, which is protected
127 * by its own lock.
128 */
129 int fd;
130 char *name;
131 struct cds_lfht_node tracker_node;
132};
133
134static struct {
135 pthread_mutex_t lock;
136 bool initialized;
137 unsigned long value;
138} seed = {
139 .lock = PTHREAD_MUTEX_INITIALIZER,
140};
141
142static int match_fd(struct cds_lfht_node *node, const void *key);
143static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry);
144static struct unsuspendable_fd *unsuspendable_fd_create(const char *name,
145 int fd);
146static int open_from_properties(struct open_properties *properties);
147
148static void fs_handle_log(struct fs_handle *handle);
149static int fs_handle_suspend(struct fs_handle *handle);
150static int fs_handle_restore(struct fs_handle *handle);
151
152static void fd_tracker_track(struct fd_tracker *tracker,
153 struct fs_handle *handle);
154static void fd_tracker_untrack(struct fd_tracker *tracker,
155 struct fs_handle *handle);
156static int fd_tracker_suspend_handles(struct fd_tracker *tracker,
157 unsigned int count);
158static int fd_tracker_restore_handle(struct fd_tracker *tracker,
159 struct fs_handle *handle);
160
161/* Match function of the tracker's unsuspendable_fds hash table. */
162static
163int match_fd(struct cds_lfht_node *node, const void *key)
164{
165 struct unsuspendable_fd *entry =
166 caa_container_of(node, struct unsuspendable_fd, tracker_node);
167
168 return hash_match_key_ulong((void *) (unsigned long) entry->fd,
169 (void *) key);
170}
171
172static
173void unsuspendable_fd_destroy(struct unsuspendable_fd *entry)
174{
175 if (!entry) {
176 return;
177 }
178 free(entry->name);
179 free(entry);
180}
181
182static
183struct unsuspendable_fd *unsuspendable_fd_create(const char *name, int fd)
184{
185 struct unsuspendable_fd *entry =
186 zmalloc(sizeof(*entry));
187
188 if (!entry) {
189 goto error;
190 }
191 if (name) {
192 entry->name = strdup(name);
193 if (!entry->name) {
194 goto error;
195 }
196 }
197 cds_lfht_node_init(&entry->tracker_node);
198 entry->fd = fd;
199 return entry;
200error:
201 unsuspendable_fd_destroy(entry);
202 return NULL;
203}
204
205static
206void fs_handle_log(struct fs_handle *handle)
207{
208 pthread_mutex_lock(&handle->lock);
209 if (handle->fd >= 0) {
210 DBG_NO_LOC(" %s [active, fd %d%s]",
211 handle->properties.path,
212 handle->fd,
213 handle->in_use ? ", in use" : "");
214 } else {
215 DBG_NO_LOC(" %s [suspended]", handle->properties.path);
216 }
217 pthread_mutex_unlock(&handle->lock);
218}
219
220static
221int fs_handle_suspend(struct fs_handle *handle)
222{
223 int ret = 0;
224 struct stat fs_stat;
225
226 pthread_mutex_lock(&handle->lock);
227 assert(handle->fd >= 0);
228 if (handle->in_use) {
229 /* This handle can't be suspended as it is currently in use. */
230 ret = -EAGAIN;
231 goto end;
232 }
233
234 ret = stat(handle->properties.path, &fs_stat);
235 if (ret) {
236 PERROR("Filesystem handle to %s cannot be suspended as stat() failed",
237 handle->properties.path);
238 ret = -errno;
239 goto end;
240 }
241
242 if (fs_stat.st_ino != handle->ino) {
243 /* Don't suspend as the handle would not be restorable. */
244 WARN("Filesystem handle to %s cannot be suspended as its inode changed",
245 handle->properties.path);
246 ret = -ENOENT;
247 goto end;
248 }
249
250 handle->offset = lseek(handle->fd, 0, SEEK_CUR);
251 if (handle->offset == -1) {
252 WARN("Filesystem handle to %s cannot be suspended as lseek() failed to sample its current position",
253 handle->properties.path);
254 ret = -errno;
255 goto end;
256 }
257
258 ret = close(handle->fd);
259 if (ret) {
260 PERROR("Filesystem handle to %s cannot be suspended as close() failed",
261 handle->properties.path);
262 ret = -errno;
263 goto end;
264 }
265 DBG("Suspended filesystem handle to %s (fd %i) at position %" PRId64,
266 handle->properties.path, handle->fd, handle->offset);
267 handle->fd = -1;
268end:
269 if (ret) {
270 handle->tracker->stats.errors++;
271 }
272 pthread_mutex_unlock(&handle->lock);
273 return ret;
274}
275
276/* Caller must hold the tracker and handle's locks. */
277static
278int fs_handle_restore(struct fs_handle *handle)
279{
280 int ret, fd = -1;
281
282 assert(handle->fd == -1);
283 ret = open_from_properties(&handle->properties);
284 if (ret < 0) {
285 PERROR("Failed to restore filesystem handle to %s, open() failed",
286 handle->properties.path);
287 ret = -errno;
288 goto end;
289 }
290 fd = ret;
291
292 ret = lseek(fd, handle->offset, SEEK_SET);
293 if (ret < 0) {
294 PERROR("Failed to restore filesystem handle to %s, lseek() failed",
295 handle->properties.path);
296 ret = -errno;
297 goto end;
298 }
299 DBG("Restored filesystem handle to %s (fd %i) at position %" PRId64,
300 handle->properties.path, fd, handle->offset);
301 ret = 0;
302 handle->fd = fd;
303 fd = -1;
304end:
305 if (fd >= 0) {
306 (void) close(fd);
307 }
308 return ret;
309}
310
311static
312int open_from_properties(struct open_properties *properties)
313{
314 int ret;
315
316 /*
317 * open() ignores the 'flags' parameter unless the O_CREAT or O_TMPFILE
318 * flags are set. O_TMPFILE would not make sense in the context of a
319 * suspendable fs_handle as it would not be restorable (see OPEN(2)),
320 * thus it is ignored here.
321 */
322 if ((properties->flags & O_CREAT) && properties->mode.is_set) {
323 ret = open(properties->path, properties->flags,
324 properties->mode.value);
325 } else {
326 ret = open(properties->path, properties->flags);
327 }
328 /*
329 * Some flags should not be used beyond the initial open() of a
330 * restorable file system handle. O_CREAT and O_TRUNC must
331 * be cleared since it would be unexpected to re-use them
332 * when the handle is retored:
333 * - O_CREAT should not be needed as the file has been created
334 * on the initial call to open(),
335 * - O_TRUNC would destroy the file's contents by truncating it
336 * to length 0.
337 */
338 properties->flags &= ~(O_CREAT | O_TRUNC);
339 if (ret < 0) {
340 ret = -errno;
341 goto end;
342 }
343end:
344 return ret;
345}
346
347struct fd_tracker *fd_tracker_create(unsigned int capacity)
348{
349 struct fd_tracker *tracker = zmalloc(sizeof(struct fd_tracker));
350
351 if (!tracker) {
352 goto end;
353 }
354
355 pthread_mutex_lock(&seed.lock);
356 if (!seed.initialized) {
357 seed.value = (unsigned long) time(NULL);
358 seed.initialized = true;
359 }
360 pthread_mutex_unlock(&seed.lock);
361
362 CDS_INIT_LIST_HEAD(&tracker->active_handles);
363 CDS_INIT_LIST_HEAD(&tracker->suspended_handles);
364 tracker->capacity = capacity;
365 tracker->unsuspendable_fds = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
366 CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL);
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367 DBG("File descriptor tracker created with a limit of %u simultaneously-opened FDs",
368 capacity);
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369end:
370 return tracker;
371}
372
373void fd_tracker_log(struct fd_tracker *tracker)
374{
375 struct fs_handle *handle;
376 struct unsuspendable_fd *unsuspendable_fd;
377 struct cds_lfht_iter iter;
378
379 pthread_mutex_lock(&tracker->lock);
380 DBG_NO_LOC("File descriptor tracker");
381 DBG_NO_LOC(" Stats:");
382 DBG_NO_LOC(" uses: %" PRIu64, tracker->stats.uses);
383 DBG_NO_LOC(" misses: %" PRIu64, tracker->stats.misses);
384 DBG_NO_LOC(" errors: %" PRIu64, tracker->stats.errors);
385 DBG_NO_LOC(" Tracked: %u", TRACKED_COUNT(tracker));
386 DBG_NO_LOC(" active: %u", ACTIVE_COUNT(tracker));
387 DBG_NO_LOC(" suspendable: %u", SUSPENDABLE_COUNT(tracker));
388 DBG_NO_LOC(" unsuspendable: %u", UNSUSPENDABLE_COUNT(tracker));
389 DBG_NO_LOC(" suspended: %u", SUSPENDED_COUNT(tracker));
390 DBG_NO_LOC(" capacity: %u", tracker->capacity);
391
392 DBG_NO_LOC(" Tracked suspendable file descriptors");
393 cds_list_for_each_entry(handle, &tracker->active_handles,
394 handles_list_node) {
395 fs_handle_log(handle);
396 }
397 cds_list_for_each_entry(handle, &tracker->suspended_handles,
398 handles_list_node) {
399 fs_handle_log(handle);
400 }
401 if (!SUSPENDABLE_COUNT(tracker)) {
402 DBG_NO_LOC(" None");
403 }
404
405 DBG_NO_LOC(" Tracked unsuspendable file descriptors");
406 rcu_read_lock();
407 cds_lfht_for_each_entry(tracker->unsuspendable_fds, &iter,
408 unsuspendable_fd, tracker_node) {
409 DBG_NO_LOC(" %s [active, fd %d]", unsuspendable_fd->name ? : "Unnamed",
410 unsuspendable_fd->fd);
411 }
412 rcu_read_unlock();
413 if (!UNSUSPENDABLE_COUNT(tracker)) {
414 DBG_NO_LOC(" None");
415 }
416
417 pthread_mutex_unlock(&tracker->lock);
418}
419
420int fd_tracker_destroy(struct fd_tracker *tracker)
421{
422 int ret = 0;
423
424 /*
425 * Refuse to destroy the tracker as fs_handles may still old
426 * weak references to the tracker.
427 */
428 pthread_mutex_lock(&tracker->lock);
429 if (TRACKED_COUNT(tracker)) {
430 ERR("A file descriptor leak has been detected: %u tracked file descriptors are still being tracked",
431 TRACKED_COUNT(tracker));
432 pthread_mutex_unlock(&tracker->lock);
433 fd_tracker_log(tracker);
434 ret = -1;
435 goto end;
436 }
437 pthread_mutex_unlock(&tracker->lock);
438
439 ret = cds_lfht_destroy(tracker->unsuspendable_fds, NULL);
440 assert(!ret);
441 pthread_mutex_destroy(&tracker->lock);
442 free(tracker);
443end:
444 return ret;
445}
446
447struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker,
448 const char *path, int flags, mode_t *mode)
449{
450 int ret;
451 struct fs_handle *handle = NULL;
452 struct stat fd_stat;
453 struct open_properties properties = {
454 .path = strdup(path),
455 .flags = flags,
456 .mode.is_set = !!mode,
457 .mode.value = mode ? *mode : 0,
458 };
459
460 if (!properties.path) {
461 goto end;
462 }
463
464 pthread_mutex_lock(&tracker->lock);
465 if (ACTIVE_COUNT(tracker) == tracker->capacity) {
466 if (tracker->count.suspendable.active > 0) {
467 ret = fd_tracker_suspend_handles(tracker, 1);
468 if (ret) {
469 goto error_destroy;
470 }
471 } else {
472 /*
473 * There are not enough active suspendable file
474 * descriptors to open a new fd and still accomodate the
475 * tracker's capacity.
476 */
477 WARN("Cannot open file system handle, too many unsuspendable file descriptors are opened (%u)",
478 tracker->count.unsuspendable);
479 ret = -EMFILE;
480 goto error_destroy;
481 }
482 }
483
484 handle = zmalloc(sizeof(*handle));
485 if (!handle) {
486 goto end;
487 }
488
489 ret = pthread_mutex_init(&handle->lock, NULL);
490 if (ret) {
491 PERROR("Failed to initialize handle mutex while creating fs handle");
492 free(handle);
493 goto end;
494 }
495
496 handle->fd = open_from_properties(&properties);
497 if (handle->fd < 0) {
498 PERROR("Failed to open fs handle to %s, open() returned", path);
499 ret = -errno;
500 goto error_destroy;
501 }
502
503 /*
504 * Clear the create flag from the open flags as it would make no sense
505 * to use it when restoring a fs handle.
506 */
507 properties.flags &= ~O_CREAT;
508 handle->properties = properties;
509 properties.path = NULL;
510
511 if (fstat(handle->fd, &fd_stat)) {
512 PERROR("Failed to retrieve file descriptor inode while creating fs handle, fstat() returned");
513 ret = -errno;
514 goto error_destroy;
515 }
516 handle->ino = fd_stat.st_ino;
517
518 fd_tracker_track(tracker, handle);
519 handle->tracker = tracker;
520 pthread_mutex_unlock(&tracker->lock);
521end:
522 free(properties.path);
523 return handle;
524error_destroy:
525 pthread_mutex_unlock(&tracker->lock);
526 (void) fs_handle_close(handle);
527 handle = NULL;
528 goto end;
529}
530
531/* Caller must hold the tracker's lock. */
532static
533int fd_tracker_suspend_handles(struct fd_tracker *tracker,
534 unsigned int count)
535{
536 unsigned int left_to_close = count;
537 struct fs_handle *handle, *tmp;
538
539 cds_list_for_each_entry_safe(handle, tmp, &tracker->active_handles,
540 handles_list_node) {
541 int ret;
542
543 fd_tracker_untrack(tracker, handle);
544 ret = fs_handle_suspend(handle);
545 fd_tracker_track(tracker, handle);
546 if (!ret) {
547 left_to_close--;
548 }
549
550 if (!left_to_close) {
551 break;
552 }
553 }
554 return left_to_close ? -EMFILE : 0;
555}
556
557int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker,
558 int *out_fds, const char **names, unsigned int fd_count,
559 fd_open_cb open, void *user_data)
560{
561 int ret, user_ret, i, fds_to_suspend;
562 unsigned int active_fds;
563 struct unsuspendable_fd *entries[fd_count];
564
565 memset(entries, 0, sizeof(entries));
566
567 pthread_mutex_lock(&tracker->lock);
568
569 active_fds = ACTIVE_COUNT(tracker);
570 fds_to_suspend = (int) active_fds + (int) fd_count - (int) tracker->capacity;
571 if (fds_to_suspend > 0) {
572 if (fds_to_suspend <= tracker->count.suspendable.active) {
573 ret = fd_tracker_suspend_handles(tracker, fds_to_suspend);
574 if (ret) {
575 goto end;
576 }
577 } else {
578 /*
579 * There are not enough active suspendable file
580 * descriptors to open a new fd and still accomodate the
581 * tracker's capacity.
582 */
583 WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)",
584 tracker->count.unsuspendable);
585 ret = -EMFILE;
586 goto end;
587 }
588 }
589
590 user_ret = open(user_data, out_fds);
591 if (user_ret) {
592 ret = user_ret;
593 goto end;
594 }
595
596 /*
597 * Add the fds returned by the user's callback to the hashtable
598 * of unsuspendable fds.
599 */
600 for (i = 0; i < fd_count; i++) {
601 struct unsuspendable_fd *entry =
602 unsuspendable_fd_create(names ? names[i] : NULL,
603 out_fds[i]);
604
605 if (!entry) {
606 ret = -1;
607 goto end_free_entries;
608 }
609 entries[i] = entry;
610 }
611
612 rcu_read_lock();
613 for (i = 0; i < fd_count; i++) {
614 struct cds_lfht_node *node;
615 struct unsuspendable_fd *entry = entries[i];
616
617 node = cds_lfht_add_unique(
618 tracker->unsuspendable_fds,
619 hash_key_ulong((void *) (unsigned long) out_fds[i],
620 seed.value),
621 match_fd,
622 (void *) (unsigned long) out_fds[i],
623 &entry->tracker_node);
624
625 if (node != &entry->tracker_node) {
626 ret = -EEXIST;
627 rcu_read_unlock();
628 goto end_free_entries;
629 }
630 entries[i] = NULL;
631 }
632 tracker->count.unsuspendable += fd_count;
633 rcu_read_unlock();
634 ret = user_ret;
635end:
636 pthread_mutex_unlock(&tracker->lock);
637 return ret;
638end_free_entries:
639 for (i = 0; i < fd_count; i++) {
640 unsuspendable_fd_destroy(entries[i]);
641 }
642 goto end;
643}
644
645int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker,
646 int *fds_in, unsigned int fd_count, fd_close_cb close,
647 void *user_data)
648{
649 int i, ret, user_ret;
650 int fds[fd_count];
651
652 /*
653 * Maintain a local copy of fds_in as the user's callback may modify its
654 * contents (e.g. setting the fd(s) to -1 after close).
655 */
656 memcpy(fds, fds_in, sizeof(*fds) * fd_count);
657
658 pthread_mutex_lock(&tracker->lock);
659 rcu_read_lock();
660
661 /* Let the user close the file descriptors. */
662 user_ret = close(user_data, fds_in);
663 if (user_ret) {
664 ret = user_ret;
665 goto end;
666 }
667
668 /* Untrack the fds that were just closed by the user's callback. */
669 for (i = 0; i < fd_count; i++) {
670 struct cds_lfht_node *node;
671 struct cds_lfht_iter iter;
672 struct unsuspendable_fd *entry;
673
674 cds_lfht_lookup(tracker->unsuspendable_fds,
675 hash_key_ulong((void *) (unsigned long) fds[i],
676 seed.value),
677 match_fd,
678 (void *) (unsigned long) fds[i],
679 &iter);
680 node = cds_lfht_iter_get_node(&iter);
681 if (!node) {
682 /* Unknown file descriptor. */
683 WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()",
684 fds[i]);
685 ret = -EINVAL;
686 goto end;
687 }
688 entry = caa_container_of(node,
689 struct unsuspendable_fd,
690 tracker_node);
691
692 cds_lfht_del(tracker->unsuspendable_fds, node);
693 unsuspendable_fd_destroy(entry);
694 fds[i] = -1;
695 }
696
697 tracker->count.unsuspendable -= fd_count;
698 ret = 0;
699end:
700 rcu_read_unlock();
701 pthread_mutex_unlock(&tracker->lock);
702 return ret;
703}
704
705/* Caller must have taken the tracker's and handle's locks. */
706static
707void fd_tracker_track(struct fd_tracker *tracker, struct fs_handle *handle)
708{
709 if (handle->fd >= 0) {
710 tracker->count.suspendable.active++;
711 cds_list_add_tail(&handle->handles_list_node,
712 &tracker->active_handles);
713 } else {
714 tracker->count.suspendable.suspended++;
715 cds_list_add_tail(&handle->handles_list_node,
716 &tracker->suspended_handles);
717 }
718}
719
720/* Caller must have taken the tracker's and handle's locks. */
721static
722void fd_tracker_untrack(struct fd_tracker *tracker, struct fs_handle *handle)
723{
724 if (handle->fd >= 0) {
725 tracker->count.suspendable.active--;
726 } else {
727 tracker->count.suspendable.suspended--;
728 }
729 cds_list_del(&handle->handles_list_node);
730}
731
732/* Caller must have taken the tracker's and handle's locks. */
733static
734int fd_tracker_restore_handle(struct fd_tracker *tracker,
735 struct fs_handle *handle)
736{
737 int ret;
738
739 fd_tracker_untrack(tracker, handle);
740 if (ACTIVE_COUNT(tracker) >= tracker->capacity) {
741 ret = fd_tracker_suspend_handles(tracker, 1);
742 if (ret) {
743 goto end;
744 }
745 }
746 ret = fs_handle_restore(handle);
747end:
748 fd_tracker_track(tracker, handle);
749 return ret ? ret : handle->fd;
750}
751
752int fs_handle_get_fd(struct fs_handle *handle)
753{
754 int ret;
755
97c34b30
JG
756 /*
757 * TODO This should be optimized as it is a fairly hot path.
758 * The fd-tracker's lock should only be taken when a fs_handle is
759 * restored (slow path). On the fast path (fs_handle is active),
760 * the only effect on the fd_tracker is marking the handle as the
761 * most recently used. Currently, it is done by a call to the
762 * track/untrack helpers, but it should be done atomically.
763 *
764 * Note that the lock's nesting order must still be respected here.
765 * The handle's lock nests inside the tracker's lock.
766 */
0ad3c26c
JG
767 pthread_mutex_lock(&handle->tracker->lock);
768 pthread_mutex_lock(&handle->lock);
769 assert(!handle->in_use);
770
771 handle->tracker->stats.uses++;
772 if (handle->fd >= 0) {
773 ret = handle->fd;
774 /* Mark as most recently used. */
775 fd_tracker_untrack(handle->tracker, handle);
776 fd_tracker_track(handle->tracker, handle);
777 } else {
778 handle->tracker->stats.misses++;
779 ret = fd_tracker_restore_handle(handle->tracker, handle);
780 if (ret < 0) {
781 handle->tracker->stats.errors++;
782 goto end;
783 }
784 }
785 handle->in_use = true;
786end:
787 pthread_mutex_unlock(&handle->lock);
788 pthread_mutex_unlock(&handle->tracker->lock);
789 return ret;
790}
791
792void fs_handle_put_fd(struct fs_handle *handle)
793{
794 pthread_mutex_lock(&handle->lock);
795 handle->in_use = false;
796 pthread_mutex_unlock(&handle->lock);
797}
798
799int fs_handle_close(struct fs_handle *handle)
800{
801 int ret = 0;
802
803 if (!handle) {
804 ret = -EINVAL;
805 goto end;
806 }
807
808 pthread_mutex_lock(&handle->tracker->lock);
809 pthread_mutex_lock(&handle->lock);
810 fd_tracker_untrack(handle->tracker, handle);
811 if (handle->fd >= 0) {
bdafebb5 812 assert(!handle->in_use);
0ad3c26c
JG
813 /*
814 * The return value of close() is not propagated as there
815 * isn't much the user can do about it.
816 */
817 if (close(handle->fd)) {
818 PERROR("Failed to close the file descritptor (%d) of fs handle to %s, close() returned",
819 handle->fd, handle->properties.path);
820 }
821 handle->fd = -1;
822 }
823 pthread_mutex_unlock(&handle->lock);
824 pthread_mutex_destroy(&handle->lock);
825 pthread_mutex_unlock(&handle->tracker->lock);
826 free(handle->properties.path);
827 free(handle);
828end:
829 return ret;
830}
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