Commit | Line | Data |
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df038819 | 1 | /* |
ab5be9fa | 2 | * Copyright (C) 2018-2020 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
df038819 | 3 | * |
ab5be9fa | 4 | * SPDX-License-Identifier: GPL-2.0-only |
df038819 | 5 | * |
df038819 JG |
6 | */ |
7 | ||
8 | #include <urcu.h> | |
9 | #include <urcu/list.h> | |
10 | #include <urcu/rculfhash.h> | |
11 | ||
df038819 | 12 | #include <fcntl.h> |
df038819 | 13 | #include <inttypes.h> |
5c1f54d1 JG |
14 | #include <pthread.h> |
15 | #include <stdbool.h> | |
16 | #include <sys/stat.h> | |
17 | #include <sys/types.h> | |
df038819 | 18 | |
f5ea0241 JG |
19 | #include <common/defaults.h> |
20 | #include <common/error.h> | |
1e4f5625 | 21 | #include <common/fs-handle-internal.h> |
f5ea0241 JG |
22 | #include <common/hashtable/hashtable.h> |
23 | #include <common/hashtable/utils.h> | |
24 | #include <common/macros.h> | |
1e4f5625 | 25 | #include <common/optional.h> |
df038819 JG |
26 | |
27 | #include "fd-tracker.h" | |
874a3441 | 28 | #include "inode.h" |
df038819 JG |
29 | |
30 | /* Tracker lock must be taken by the user. */ | |
5c1f54d1 JG |
31 | #define TRACKED_COUNT(tracker) \ |
32 | (tracker->count.suspendable.active + \ | |
33 | tracker->count.suspendable.suspended + \ | |
34 | tracker->count.unsuspendable) | |
df038819 JG |
35 | |
36 | /* Tracker lock must be taken by the user. */ | |
5c1f54d1 JG |
37 | #define ACTIVE_COUNT(tracker) \ |
38 | (tracker->count.suspendable.active + tracker->count.unsuspendable) | |
df038819 JG |
39 | |
40 | /* Tracker lock must be taken by the user. */ | |
5c1f54d1 | 41 | #define SUSPENDED_COUNT(tracker) (tracker->count.suspendable.suspended) |
df038819 JG |
42 | |
43 | /* Tracker lock must be taken by the user. */ | |
5c1f54d1 JG |
44 | #define SUSPENDABLE_COUNT(tracker) \ |
45 | (tracker->count.suspendable.active + \ | |
46 | tracker->count.suspendable.suspended) | |
df038819 JG |
47 | |
48 | /* Tracker lock must be taken by the user. */ | |
5c1f54d1 | 49 | #define UNSUSPENDABLE_COUNT(tracker) (tracker->count.unsuspendable) |
df038819 JG |
50 | |
51 | struct fd_tracker { | |
52 | pthread_mutex_t lock; | |
53 | struct { | |
5c1f54d1 | 54 | struct { |
df038819 JG |
55 | unsigned int active; |
56 | unsigned int suspended; | |
57 | } suspendable; | |
58 | unsigned int unsuspendable; | |
59 | } count; | |
60 | unsigned int capacity; | |
61 | struct { | |
62 | uint64_t uses; | |
63 | uint64_t misses; | |
64 | /* Failures to suspend or restore fs handles. */ | |
65 | uint64_t errors; | |
66 | } stats; | |
67 | /* | |
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. | |
73 | */ | |
74 | struct cds_list_head active_handles; | |
75 | struct cds_list_head suspended_handles; | |
76 | struct cds_lfht *unsuspendable_fds; | |
874a3441 | 77 | struct lttng_inode_registry *inode_registry; |
f7c3ffd7 JG |
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; | |
df038819 JG |
81 | }; |
82 | ||
83 | struct open_properties { | |
df038819 | 84 | int flags; |
1e4f5625 | 85 | LTTNG_OPTIONAL(mode_t) mode; |
df038819 JG |
86 | }; |
87 | ||
88 | /* | |
f5ea0241 | 89 | * A fs_handle_tracked is not ref-counted. Therefore, it is assumed that a |
df038819 JG |
90 | * handle is never in-use while it is being reclaimed. It can be |
91 | * shared by multiple threads, but external synchronization is required | |
92 | * to ensure it is not still being used when it is reclaimed (close method). | |
93 | * In this respect, it is not different from a regular file descriptor. | |
94 | * | |
95 | * The fs_handle lock always nests _within_ the tracker's lock. | |
96 | */ | |
f5ea0241 JG |
97 | struct fs_handle_tracked { |
98 | struct fs_handle parent; | |
df038819 JG |
99 | pthread_mutex_t lock; |
100 | /* | |
101 | * Weak reference to the tracker. All fs_handles are assumed to have | |
102 | * been closed at the moment of the destruction of the fd_tracker. | |
103 | */ | |
104 | struct fd_tracker *tracker; | |
105 | struct open_properties properties; | |
874a3441 | 106 | struct lttng_inode *inode; |
df038819 JG |
107 | int fd; |
108 | /* inode number of the file at the time of the handle's creation. */ | |
109 | uint64_t ino; | |
110 | bool in_use; | |
111 | /* Offset to which the file should be restored. */ | |
112 | off_t offset; | |
113 | struct cds_list_head handles_list_node; | |
114 | }; | |
115 | ||
116 | struct unsuspendable_fd { | |
117 | /* | |
118 | * Accesses are only performed through the tracker, which is protected | |
119 | * by its own lock. | |
120 | */ | |
121 | int fd; | |
122 | char *name; | |
123 | struct cds_lfht_node tracker_node; | |
124 | struct rcu_head rcu_head; | |
125 | }; | |
126 | ||
127 | static struct { | |
128 | pthread_mutex_t lock; | |
129 | bool initialized; | |
130 | unsigned long value; | |
131 | } seed = { | |
132 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
133 | }; | |
134 | ||
135 | static int match_fd(struct cds_lfht_node *node, const void *key); | |
136 | static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry); | |
5c1f54d1 JG |
137 | static struct unsuspendable_fd *unsuspendable_fd_create( |
138 | const char *name, int fd); | |
f7c3ffd7 | 139 | static int open_from_properties(const struct lttng_directory_handle *dir_handle, |
5c1f54d1 | 140 | const char *path, struct open_properties *properties); |
df038819 | 141 | |
f5ea0241 JG |
142 | static void fs_handle_tracked_log(struct fs_handle_tracked *handle); |
143 | static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle); | |
144 | static int fs_handle_tracked_restore(struct fs_handle_tracked *handle); | |
145 | static int fs_handle_tracked_get_fd(struct fs_handle *_handle); | |
146 | static void fs_handle_tracked_put_fd(struct fs_handle *_handle); | |
147 | static int fs_handle_tracked_unlink(struct fs_handle *_handle); | |
148 | static int fs_handle_tracked_close(struct fs_handle *_handle); | |
df038819 | 149 | |
5c1f54d1 | 150 | static void fd_tracker_track( |
f5ea0241 | 151 | struct fd_tracker *tracker, struct fs_handle_tracked *handle); |
5c1f54d1 | 152 | static void fd_tracker_untrack( |
f5ea0241 | 153 | struct fd_tracker *tracker, struct fs_handle_tracked *handle); |
5c1f54d1 JG |
154 | static int fd_tracker_suspend_handles( |
155 | struct fd_tracker *tracker, unsigned int count); | |
156 | static int fd_tracker_restore_handle( | |
f5ea0241 JG |
157 | struct fd_tracker *tracker, struct fs_handle_tracked *handle); |
158 | ||
df038819 | 159 | /* Match function of the tracker's unsuspendable_fds hash table. */ |
5c1f54d1 | 160 | static int match_fd(struct cds_lfht_node *node, const void *key) |
df038819 | 161 | { |
5c1f54d1 JG |
162 | struct unsuspendable_fd *entry = caa_container_of( |
163 | node, struct unsuspendable_fd, tracker_node); | |
df038819 | 164 | |
5c1f54d1 JG |
165 | return hash_match_key_ulong( |
166 | (void *) (unsigned long) entry->fd, (void *) key); | |
df038819 JG |
167 | } |
168 | ||
5c1f54d1 | 169 | static void delete_unsuspendable_fd(struct rcu_head *head) |
df038819 | 170 | { |
5c1f54d1 JG |
171 | struct unsuspendable_fd *fd = caa_container_of( |
172 | head, struct unsuspendable_fd, rcu_head); | |
df038819 JG |
173 | |
174 | free(fd->name); | |
175 | free(fd); | |
176 | } | |
177 | ||
5c1f54d1 | 178 | static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry) |
df038819 JG |
179 | { |
180 | if (!entry) { | |
181 | return; | |
182 | } | |
183 | call_rcu(&entry->rcu_head, delete_unsuspendable_fd); | |
184 | } | |
185 | ||
5c1f54d1 JG |
186 | static struct unsuspendable_fd *unsuspendable_fd_create( |
187 | const char *name, int fd) | |
df038819 | 188 | { |
5c1f54d1 | 189 | struct unsuspendable_fd *entry = zmalloc(sizeof(*entry)); |
df038819 JG |
190 | |
191 | if (!entry) { | |
192 | goto error; | |
193 | } | |
194 | if (name) { | |
195 | entry->name = strdup(name); | |
196 | if (!entry->name) { | |
197 | goto error; | |
198 | } | |
199 | } | |
200 | cds_lfht_node_init(&entry->tracker_node); | |
201 | entry->fd = fd; | |
202 | return entry; | |
203 | error: | |
204 | unsuspendable_fd_destroy(entry); | |
205 | return NULL; | |
206 | } | |
207 | ||
f5ea0241 | 208 | static void fs_handle_tracked_log(struct fs_handle_tracked *handle) |
df038819 | 209 | { |
874a3441 JG |
210 | const char *path; |
211 | ||
df038819 | 212 | pthread_mutex_lock(&handle->lock); |
dd95933f | 213 | lttng_inode_borrow_location(handle->inode, NULL, &path); |
874a3441 | 214 | |
df038819 | 215 | if (handle->fd >= 0) { |
5c1f54d1 | 216 | DBG_NO_LOC(" %s [active, fd %d%s]", path, handle->fd, |
df038819 JG |
217 | handle->in_use ? ", in use" : ""); |
218 | } else { | |
874a3441 | 219 | DBG_NO_LOC(" %s [suspended]", path); |
df038819 JG |
220 | } |
221 | pthread_mutex_unlock(&handle->lock); | |
222 | } | |
223 | ||
874a3441 | 224 | /* Tracker lock must be held by the caller. */ |
f5ea0241 | 225 | static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle) |
df038819 JG |
226 | { |
227 | int ret = 0; | |
228 | struct stat fs_stat; | |
874a3441 | 229 | const char *path; |
f7c3ffd7 | 230 | const struct lttng_directory_handle *node_directory_handle; |
df038819 JG |
231 | |
232 | pthread_mutex_lock(&handle->lock); | |
dd95933f JG |
233 | lttng_inode_borrow_location( |
234 | handle->inode, &node_directory_handle, &path); | |
df038819 JG |
235 | assert(handle->fd >= 0); |
236 | if (handle->in_use) { | |
237 | /* This handle can't be suspended as it is currently in use. */ | |
238 | ret = -EAGAIN; | |
239 | goto end; | |
240 | } | |
241 | ||
f7c3ffd7 JG |
242 | ret = lttng_directory_handle_stat( |
243 | node_directory_handle, path, &fs_stat); | |
df038819 | 244 | if (ret) { |
5c1f54d1 | 245 | PERROR("Filesystem handle to %s cannot be suspended as stat() failed", |
874a3441 | 246 | path); |
df038819 JG |
247 | ret = -errno; |
248 | goto end; | |
249 | } | |
250 | ||
251 | if (fs_stat.st_ino != handle->ino) { | |
252 | /* Don't suspend as the handle would not be restorable. */ | |
253 | WARN("Filesystem handle to %s cannot be suspended as its inode changed", | |
874a3441 | 254 | path); |
df038819 JG |
255 | ret = -ENOENT; |
256 | goto end; | |
257 | } | |
258 | ||
5c1f54d1 | 259 | handle->offset = lseek(handle->fd, 0, SEEK_CUR); |
df038819 JG |
260 | if (handle->offset == -1) { |
261 | WARN("Filesystem handle to %s cannot be suspended as lseek() failed to sample its current position", | |
874a3441 | 262 | path); |
df038819 JG |
263 | ret = -errno; |
264 | goto end; | |
265 | } | |
266 | ||
267 | ret = close(handle->fd); | |
268 | if (ret) { | |
5c1f54d1 | 269 | PERROR("Filesystem handle to %s cannot be suspended as close() failed", |
874a3441 | 270 | path); |
df038819 JG |
271 | ret = -errno; |
272 | goto end; | |
273 | } | |
274 | DBG("Suspended filesystem handle to %s (fd %i) at position %" PRId64, | |
874a3441 | 275 | path, handle->fd, handle->offset); |
df038819 JG |
276 | handle->fd = -1; |
277 | end: | |
278 | if (ret) { | |
279 | handle->tracker->stats.errors++; | |
280 | } | |
281 | pthread_mutex_unlock(&handle->lock); | |
282 | return ret; | |
283 | } | |
284 | ||
285 | /* Caller must hold the tracker and handle's locks. */ | |
f5ea0241 | 286 | static int fs_handle_tracked_restore(struct fs_handle_tracked *handle) |
df038819 JG |
287 | { |
288 | int ret, fd = -1; | |
f7c3ffd7 JG |
289 | const char *path; |
290 | const struct lttng_directory_handle *node_directory_handle; | |
291 | ||
dd95933f JG |
292 | lttng_inode_borrow_location( |
293 | handle->inode, &node_directory_handle, &path); | |
df038819 JG |
294 | |
295 | assert(handle->fd == -1); | |
874a3441 | 296 | assert(path); |
f7c3ffd7 JG |
297 | ret = open_from_properties( |
298 | node_directory_handle, path, &handle->properties); | |
df038819 | 299 | if (ret < 0) { |
5c1f54d1 | 300 | PERROR("Failed to restore filesystem handle to %s, open() failed", |
874a3441 | 301 | path); |
df038819 JG |
302 | ret = -errno; |
303 | goto end; | |
304 | } | |
305 | fd = ret; | |
306 | ||
307 | ret = lseek(fd, handle->offset, SEEK_SET); | |
308 | if (ret < 0) { | |
5c1f54d1 | 309 | PERROR("Failed to restore filesystem handle to %s, lseek() failed", |
874a3441 | 310 | path); |
df038819 JG |
311 | ret = -errno; |
312 | goto end; | |
313 | } | |
314 | DBG("Restored filesystem handle to %s (fd %i) at position %" PRId64, | |
874a3441 | 315 | path, fd, handle->offset); |
df038819 JG |
316 | ret = 0; |
317 | handle->fd = fd; | |
318 | fd = -1; | |
319 | end: | |
320 | if (fd >= 0) { | |
321 | (void) close(fd); | |
322 | } | |
323 | return ret; | |
324 | } | |
325 | ||
f7c3ffd7 | 326 | static int open_from_properties(const struct lttng_directory_handle *dir_handle, |
5c1f54d1 | 327 | const char *path, struct open_properties *properties) |
df038819 JG |
328 | { |
329 | int ret; | |
330 | ||
331 | /* | |
332 | * open() ignores the 'flags' parameter unless the O_CREAT or O_TMPFILE | |
333 | * flags are set. O_TMPFILE would not make sense in the context of a | |
334 | * suspendable fs_handle as it would not be restorable (see OPEN(2)), | |
335 | * thus it is ignored here. | |
336 | */ | |
337 | if ((properties->flags & O_CREAT) && properties->mode.is_set) { | |
f7c3ffd7 JG |
338 | ret = lttng_directory_handle_open_file(dir_handle, path, |
339 | properties->flags, properties->mode.value); | |
df038819 | 340 | } else { |
f7c3ffd7 JG |
341 | ret = lttng_directory_handle_open_file(dir_handle, path, |
342 | properties->flags, 0); | |
df038819 JG |
343 | } |
344 | /* | |
345 | * Some flags should not be used beyond the initial open() of a | |
346 | * restorable file system handle. O_CREAT and O_TRUNC must | |
347 | * be cleared since it would be unexpected to re-use them | |
348 | * when the handle is retored: | |
349 | * - O_CREAT should not be needed as the file has been created | |
350 | * on the initial call to open(), | |
351 | * - O_TRUNC would destroy the file's contents by truncating it | |
352 | * to length 0. | |
353 | */ | |
354 | properties->flags &= ~(O_CREAT | O_TRUNC); | |
355 | if (ret < 0) { | |
356 | ret = -errno; | |
357 | goto end; | |
358 | } | |
359 | end: | |
360 | return ret; | |
361 | } | |
362 | ||
f7c3ffd7 JG |
363 | struct fd_tracker *fd_tracker_create(const char *unlinked_file_path, |
364 | unsigned int capacity) | |
df038819 JG |
365 | { |
366 | struct fd_tracker *tracker = zmalloc(sizeof(struct fd_tracker)); | |
367 | ||
368 | if (!tracker) { | |
369 | goto end; | |
370 | } | |
371 | ||
372 | pthread_mutex_lock(&seed.lock); | |
373 | if (!seed.initialized) { | |
374 | seed.value = (unsigned long) time(NULL); | |
375 | seed.initialized = true; | |
376 | } | |
377 | pthread_mutex_unlock(&seed.lock); | |
378 | ||
379 | CDS_INIT_LIST_HEAD(&tracker->active_handles); | |
380 | CDS_INIT_LIST_HEAD(&tracker->suspended_handles); | |
381 | tracker->capacity = capacity; | |
382 | tracker->unsuspendable_fds = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0, | |
383 | CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL); | |
874a3441 JG |
384 | if (!tracker->unsuspendable_fds) { |
385 | ERR("Failed to create fd-tracker's unsuspendable_fds hash table"); | |
386 | goto error; | |
387 | } | |
388 | tracker->inode_registry = lttng_inode_registry_create(); | |
389 | if (!tracker->inode_registry) { | |
390 | ERR("Failed to create fd-tracker's inode registry"); | |
391 | goto error; | |
392 | } | |
f7c3ffd7 JG |
393 | |
394 | tracker->unlinked_file_pool = | |
395 | lttng_unlinked_file_pool_create(unlinked_file_path); | |
396 | if (!tracker->unlinked_file_pool) { | |
397 | goto error; | |
398 | } | |
df038819 JG |
399 | DBG("File descriptor tracker created with a limit of %u simultaneously-opened FDs", |
400 | capacity); | |
401 | end: | |
402 | return tracker; | |
874a3441 JG |
403 | error: |
404 | fd_tracker_destroy(tracker); | |
405 | return NULL; | |
df038819 JG |
406 | } |
407 | ||
408 | void fd_tracker_log(struct fd_tracker *tracker) | |
409 | { | |
f5ea0241 | 410 | struct fs_handle_tracked *handle; |
df038819 JG |
411 | struct unsuspendable_fd *unsuspendable_fd; |
412 | struct cds_lfht_iter iter; | |
413 | ||
414 | pthread_mutex_lock(&tracker->lock); | |
415 | DBG_NO_LOC("File descriptor tracker"); | |
416 | DBG_NO_LOC(" Stats:"); | |
417 | DBG_NO_LOC(" uses: %" PRIu64, tracker->stats.uses); | |
418 | DBG_NO_LOC(" misses: %" PRIu64, tracker->stats.misses); | |
419 | DBG_NO_LOC(" errors: %" PRIu64, tracker->stats.errors); | |
420 | DBG_NO_LOC(" Tracked: %u", TRACKED_COUNT(tracker)); | |
421 | DBG_NO_LOC(" active: %u", ACTIVE_COUNT(tracker)); | |
422 | DBG_NO_LOC(" suspendable: %u", SUSPENDABLE_COUNT(tracker)); | |
423 | DBG_NO_LOC(" unsuspendable: %u", UNSUSPENDABLE_COUNT(tracker)); | |
424 | DBG_NO_LOC(" suspended: %u", SUSPENDED_COUNT(tracker)); | |
425 | DBG_NO_LOC(" capacity: %u", tracker->capacity); | |
426 | ||
427 | DBG_NO_LOC(" Tracked suspendable file descriptors"); | |
f5ea0241 | 428 | cds_list_for_each_entry( |
5c1f54d1 | 429 | handle, &tracker->active_handles, handles_list_node) { |
f5ea0241 | 430 | fs_handle_tracked_log(handle); |
df038819 | 431 | } |
f5ea0241 | 432 | cds_list_for_each_entry(handle, &tracker->suspended_handles, |
df038819 | 433 | handles_list_node) { |
f5ea0241 | 434 | fs_handle_tracked_log(handle); |
df038819 JG |
435 | } |
436 | if (!SUSPENDABLE_COUNT(tracker)) { | |
437 | DBG_NO_LOC(" None"); | |
438 | } | |
439 | ||
440 | DBG_NO_LOC(" Tracked unsuspendable file descriptors"); | |
441 | rcu_read_lock(); | |
f5ea0241 | 442 | cds_lfht_for_each_entry(tracker->unsuspendable_fds, &iter, |
df038819 | 443 | unsuspendable_fd, tracker_node) { |
5c1f54d1 JG |
444 | DBG_NO_LOC(" %s [active, fd %d]", |
445 | unsuspendable_fd->name ?: "Unnamed", | |
df038819 JG |
446 | unsuspendable_fd->fd); |
447 | } | |
448 | rcu_read_unlock(); | |
449 | if (!UNSUSPENDABLE_COUNT(tracker)) { | |
450 | DBG_NO_LOC(" None"); | |
451 | } | |
452 | ||
453 | pthread_mutex_unlock(&tracker->lock); | |
454 | } | |
455 | ||
456 | int fd_tracker_destroy(struct fd_tracker *tracker) | |
457 | { | |
458 | int ret = 0; | |
459 | ||
f6bef966 JG |
460 | if (!tracker) { |
461 | goto end; | |
462 | } | |
df038819 JG |
463 | /* |
464 | * Refuse to destroy the tracker as fs_handles may still old | |
465 | * weak references to the tracker. | |
466 | */ | |
467 | pthread_mutex_lock(&tracker->lock); | |
468 | if (TRACKED_COUNT(tracker)) { | |
469 | ERR("A file descriptor leak has been detected: %u tracked file descriptors are still being tracked", | |
470 | TRACKED_COUNT(tracker)); | |
471 | pthread_mutex_unlock(&tracker->lock); | |
472 | fd_tracker_log(tracker); | |
473 | ret = -1; | |
474 | goto end; | |
475 | } | |
476 | pthread_mutex_unlock(&tracker->lock); | |
477 | ||
874a3441 JG |
478 | if (tracker->unsuspendable_fds) { |
479 | ret = cds_lfht_destroy(tracker->unsuspendable_fds, NULL); | |
480 | assert(!ret); | |
481 | } | |
660a216c JG |
482 | |
483 | lttng_inode_registry_destroy(tracker->inode_registry); | |
f7c3ffd7 | 484 | lttng_unlinked_file_pool_destroy(tracker->unlinked_file_pool); |
df038819 JG |
485 | pthread_mutex_destroy(&tracker->lock); |
486 | free(tracker); | |
487 | end: | |
488 | return ret; | |
489 | } | |
490 | ||
491 | struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, | |
f7c3ffd7 | 492 | struct lttng_directory_handle *directory, |
5c1f54d1 JG |
493 | const char *path, |
494 | int flags, | |
495 | mode_t *mode) | |
df038819 JG |
496 | { |
497 | int ret; | |
f5ea0241 | 498 | struct fs_handle_tracked *handle = NULL; |
df038819 JG |
499 | struct stat fd_stat; |
500 | struct open_properties properties = { | |
df038819 JG |
501 | .flags = flags, |
502 | .mode.is_set = !!mode, | |
503 | .mode.value = mode ? *mode : 0, | |
504 | }; | |
505 | ||
df038819 JG |
506 | pthread_mutex_lock(&tracker->lock); |
507 | if (ACTIVE_COUNT(tracker) == tracker->capacity) { | |
508 | if (tracker->count.suspendable.active > 0) { | |
509 | ret = fd_tracker_suspend_handles(tracker, 1); | |
510 | if (ret) { | |
19380ea8 | 511 | goto end; |
df038819 JG |
512 | } |
513 | } else { | |
514 | /* | |
515 | * There are not enough active suspendable file | |
19380ea8 JG |
516 | * descriptors to open a new fd and still accommodate |
517 | * the tracker's capacity. | |
df038819 JG |
518 | */ |
519 | WARN("Cannot open file system handle, too many unsuspendable file descriptors are opened (%u)", | |
520 | tracker->count.unsuspendable); | |
19380ea8 | 521 | goto end; |
df038819 JG |
522 | } |
523 | } | |
524 | ||
525 | handle = zmalloc(sizeof(*handle)); | |
526 | if (!handle) { | |
527 | goto end; | |
528 | } | |
f7c3ffd7 JG |
529 | handle->parent = (typeof(handle->parent)) { |
530 | .get_fd = fs_handle_tracked_get_fd, | |
531 | .put_fd = fs_handle_tracked_put_fd, | |
532 | .unlink = fs_handle_tracked_unlink, | |
533 | .close = fs_handle_tracked_close, | |
534 | }; | |
535 | ||
660a216c | 536 | handle->tracker = tracker; |
df038819 JG |
537 | |
538 | ret = pthread_mutex_init(&handle->lock, NULL); | |
539 | if (ret) { | |
540 | PERROR("Failed to initialize handle mutex while creating fs handle"); | |
19380ea8 | 541 | goto error_mutex_init; |
df038819 JG |
542 | } |
543 | ||
f7c3ffd7 | 544 | handle->fd = open_from_properties(directory, path, &properties); |
df038819 JG |
545 | if (handle->fd < 0) { |
546 | PERROR("Failed to open fs handle to %s, open() returned", path); | |
19380ea8 | 547 | goto error; |
df038819 JG |
548 | } |
549 | ||
550 | handle->properties = properties; | |
874a3441 | 551 | |
f7c3ffd7 JG |
552 | handle->inode = lttng_inode_registry_get_inode(tracker->inode_registry, |
553 | directory, path, handle->fd, | |
554 | tracker->unlinked_file_pool); | |
874a3441 | 555 | if (!handle->inode) { |
5c1f54d1 | 556 | ERR("Failed to get lttng_inode corresponding to file %s", path); |
19380ea8 | 557 | goto error; |
874a3441 | 558 | } |
df038819 JG |
559 | |
560 | if (fstat(handle->fd, &fd_stat)) { | |
561 | PERROR("Failed to retrieve file descriptor inode while creating fs handle, fstat() returned"); | |
19380ea8 | 562 | goto error; |
df038819 JG |
563 | } |
564 | handle->ino = fd_stat.st_ino; | |
565 | ||
566 | fd_tracker_track(tracker, handle); | |
df038819 | 567 | end: |
19380ea8 | 568 | pthread_mutex_unlock(&tracker->lock); |
f5ea0241 | 569 | return handle ? &handle->parent : NULL; |
19380ea8 | 570 | error: |
660a216c JG |
571 | if (handle->inode) { |
572 | lttng_inode_put(handle->inode); | |
573 | } | |
19380ea8 JG |
574 | pthread_mutex_destroy(&handle->lock); |
575 | error_mutex_init: | |
660a216c | 576 | free(handle); |
df038819 JG |
577 | handle = NULL; |
578 | goto end; | |
579 | } | |
580 | ||
581 | /* Caller must hold the tracker's lock. */ | |
5c1f54d1 JG |
582 | static int fd_tracker_suspend_handles( |
583 | struct fd_tracker *tracker, unsigned int count) | |
df038819 JG |
584 | { |
585 | unsigned int left_to_close = count; | |
f7c3ffd7 | 586 | unsigned int attempts_left = tracker->count.suspendable.active; |
f5ea0241 | 587 | struct fs_handle_tracked *handle, *tmp; |
df038819 | 588 | |
f5ea0241 | 589 | cds_list_for_each_entry_safe(handle, tmp, &tracker->active_handles, |
df038819 JG |
590 | handles_list_node) { |
591 | int ret; | |
592 | ||
593 | fd_tracker_untrack(tracker, handle); | |
f5ea0241 | 594 | ret = fs_handle_tracked_suspend(handle); |
df038819 JG |
595 | fd_tracker_track(tracker, handle); |
596 | if (!ret) { | |
597 | left_to_close--; | |
598 | } | |
f7c3ffd7 | 599 | attempts_left--; |
df038819 | 600 | |
f7c3ffd7 | 601 | if (left_to_close == 0 || attempts_left == 0) { |
df038819 JG |
602 | break; |
603 | } | |
604 | } | |
605 | return left_to_close ? -EMFILE : 0; | |
606 | } | |
607 | ||
608 | int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, | |
5c1f54d1 JG |
609 | int *out_fds, |
610 | const char **names, | |
611 | unsigned int fd_count, | |
612 | fd_open_cb open, | |
613 | void *user_data) | |
df038819 JG |
614 | { |
615 | int ret, user_ret, i, fds_to_suspend; | |
616 | unsigned int active_fds; | |
b13a2b17 | 617 | struct unsuspendable_fd **entries; |
df038819 | 618 | |
b13a2b17 JG |
619 | entries = zmalloc(fd_count * sizeof(*entries)); |
620 | if (!entries) { | |
621 | ret = -1; | |
622 | goto end; | |
623 | } | |
df038819 JG |
624 | |
625 | pthread_mutex_lock(&tracker->lock); | |
626 | ||
627 | active_fds = ACTIVE_COUNT(tracker); | |
5c1f54d1 JG |
628 | fds_to_suspend = (int) active_fds + (int) fd_count - |
629 | (int) tracker->capacity; | |
df038819 JG |
630 | if (fds_to_suspend > 0) { |
631 | if (fds_to_suspend <= tracker->count.suspendable.active) { | |
5c1f54d1 JG |
632 | ret = fd_tracker_suspend_handles( |
633 | tracker, fds_to_suspend); | |
df038819 | 634 | if (ret) { |
b13a2b17 | 635 | goto end_unlock; |
df038819 JG |
636 | } |
637 | } else { | |
638 | /* | |
639 | * There are not enough active suspendable file | |
640 | * descriptors to open a new fd and still accomodate the | |
641 | * tracker's capacity. | |
642 | */ | |
643 | WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)", | |
644 | tracker->count.unsuspendable); | |
645 | ret = -EMFILE; | |
b13a2b17 | 646 | goto end_unlock; |
df038819 JG |
647 | } |
648 | } | |
649 | ||
650 | user_ret = open(user_data, out_fds); | |
651 | if (user_ret) { | |
652 | ret = user_ret; | |
b13a2b17 | 653 | goto end_unlock; |
df038819 JG |
654 | } |
655 | ||
656 | /* | |
657 | * Add the fds returned by the user's callback to the hashtable | |
658 | * of unsuspendable fds. | |
659 | */ | |
660 | for (i = 0; i < fd_count; i++) { | |
5c1f54d1 JG |
661 | struct unsuspendable_fd *entry = unsuspendable_fd_create( |
662 | names ? names[i] : NULL, out_fds[i]); | |
df038819 JG |
663 | |
664 | if (!entry) { | |
665 | ret = -1; | |
666 | goto end_free_entries; | |
667 | } | |
668 | entries[i] = entry; | |
669 | } | |
670 | ||
671 | rcu_read_lock(); | |
672 | for (i = 0; i < fd_count; i++) { | |
673 | struct cds_lfht_node *node; | |
674 | struct unsuspendable_fd *entry = entries[i]; | |
675 | ||
5c1f54d1 JG |
676 | node = cds_lfht_add_unique(tracker->unsuspendable_fds, |
677 | hash_key_ulong((void *) (unsigned long) | |
678 | out_fds[i], | |
df038819 | 679 | seed.value), |
5c1f54d1 | 680 | match_fd, (void *) (unsigned long) out_fds[i], |
df038819 JG |
681 | &entry->tracker_node); |
682 | ||
683 | if (node != &entry->tracker_node) { | |
684 | ret = -EEXIST; | |
685 | rcu_read_unlock(); | |
686 | goto end_free_entries; | |
687 | } | |
688 | entries[i] = NULL; | |
689 | } | |
690 | tracker->count.unsuspendable += fd_count; | |
691 | rcu_read_unlock(); | |
692 | ret = user_ret; | |
b13a2b17 | 693 | end_unlock: |
df038819 | 694 | pthread_mutex_unlock(&tracker->lock); |
b13a2b17 JG |
695 | end: |
696 | free(entries); | |
df038819 JG |
697 | return ret; |
698 | end_free_entries: | |
699 | for (i = 0; i < fd_count; i++) { | |
700 | unsuspendable_fd_destroy(entries[i]); | |
701 | } | |
b13a2b17 | 702 | goto end_unlock; |
df038819 JG |
703 | } |
704 | ||
705 | int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, | |
5c1f54d1 JG |
706 | int *fds_in, |
707 | unsigned int fd_count, | |
708 | fd_close_cb close, | |
df038819 JG |
709 | void *user_data) |
710 | { | |
711 | int i, ret, user_ret; | |
b13a2b17 | 712 | int *fds = NULL; |
df038819 JG |
713 | |
714 | /* | |
715 | * Maintain a local copy of fds_in as the user's callback may modify its | |
716 | * contents (e.g. setting the fd(s) to -1 after close). | |
717 | */ | |
b13a2b17 JG |
718 | fds = malloc(sizeof(*fds) * fd_count); |
719 | if (!fds) { | |
720 | ret = -1; | |
721 | goto end; | |
722 | } | |
df038819 JG |
723 | memcpy(fds, fds_in, sizeof(*fds) * fd_count); |
724 | ||
725 | pthread_mutex_lock(&tracker->lock); | |
726 | rcu_read_lock(); | |
727 | ||
728 | /* Let the user close the file descriptors. */ | |
729 | user_ret = close(user_data, fds_in); | |
730 | if (user_ret) { | |
731 | ret = user_ret; | |
b13a2b17 | 732 | goto end_unlock; |
df038819 JG |
733 | } |
734 | ||
735 | /* Untrack the fds that were just closed by the user's callback. */ | |
736 | for (i = 0; i < fd_count; i++) { | |
737 | struct cds_lfht_node *node; | |
738 | struct cds_lfht_iter iter; | |
739 | struct unsuspendable_fd *entry; | |
740 | ||
741 | cds_lfht_lookup(tracker->unsuspendable_fds, | |
742 | hash_key_ulong((void *) (unsigned long) fds[i], | |
743 | seed.value), | |
5c1f54d1 | 744 | match_fd, (void *) (unsigned long) fds[i], |
df038819 JG |
745 | &iter); |
746 | node = cds_lfht_iter_get_node(&iter); | |
747 | if (!node) { | |
748 | /* Unknown file descriptor. */ | |
749 | WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()", | |
750 | fds[i]); | |
751 | ret = -EINVAL; | |
b13a2b17 | 752 | goto end_unlock; |
df038819 | 753 | } |
5c1f54d1 JG |
754 | entry = caa_container_of( |
755 | node, struct unsuspendable_fd, tracker_node); | |
df038819 JG |
756 | |
757 | cds_lfht_del(tracker->unsuspendable_fds, node); | |
758 | unsuspendable_fd_destroy(entry); | |
759 | fds[i] = -1; | |
760 | } | |
761 | ||
762 | tracker->count.unsuspendable -= fd_count; | |
763 | ret = 0; | |
b13a2b17 | 764 | end_unlock: |
df038819 JG |
765 | rcu_read_unlock(); |
766 | pthread_mutex_unlock(&tracker->lock); | |
b13a2b17 JG |
767 | free(fds); |
768 | end: | |
df038819 JG |
769 | return ret; |
770 | } | |
771 | ||
772 | /* Caller must have taken the tracker's and handle's locks. */ | |
5c1f54d1 | 773 | static void fd_tracker_track( |
f5ea0241 | 774 | struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
775 | { |
776 | if (handle->fd >= 0) { | |
777 | tracker->count.suspendable.active++; | |
778 | cds_list_add_tail(&handle->handles_list_node, | |
779 | &tracker->active_handles); | |
780 | } else { | |
781 | tracker->count.suspendable.suspended++; | |
782 | cds_list_add_tail(&handle->handles_list_node, | |
783 | &tracker->suspended_handles); | |
784 | } | |
785 | } | |
786 | ||
787 | /* Caller must have taken the tracker's and handle's locks. */ | |
5c1f54d1 | 788 | static void fd_tracker_untrack( |
f5ea0241 | 789 | struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
790 | { |
791 | if (handle->fd >= 0) { | |
792 | tracker->count.suspendable.active--; | |
793 | } else { | |
794 | tracker->count.suspendable.suspended--; | |
795 | } | |
796 | cds_list_del(&handle->handles_list_node); | |
797 | } | |
798 | ||
799 | /* Caller must have taken the tracker's and handle's locks. */ | |
5c1f54d1 | 800 | static int fd_tracker_restore_handle( |
f5ea0241 | 801 | struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
802 | { |
803 | int ret; | |
804 | ||
805 | fd_tracker_untrack(tracker, handle); | |
806 | if (ACTIVE_COUNT(tracker) >= tracker->capacity) { | |
807 | ret = fd_tracker_suspend_handles(tracker, 1); | |
808 | if (ret) { | |
809 | goto end; | |
810 | } | |
811 | } | |
f5ea0241 | 812 | ret = fs_handle_tracked_restore(handle); |
df038819 JG |
813 | end: |
814 | fd_tracker_track(tracker, handle); | |
815 | return ret ? ret : handle->fd; | |
816 | } | |
817 | ||
f5ea0241 | 818 | static int fs_handle_tracked_get_fd(struct fs_handle *_handle) |
df038819 JG |
819 | { |
820 | int ret; | |
f5ea0241 JG |
821 | struct fs_handle_tracked *handle = |
822 | container_of(_handle, struct fs_handle_tracked, parent); | |
df038819 JG |
823 | |
824 | /* | |
825 | * TODO This should be optimized as it is a fairly hot path. | |
826 | * The fd-tracker's lock should only be taken when a fs_handle is | |
827 | * restored (slow path). On the fast path (fs_handle is active), | |
828 | * the only effect on the fd_tracker is marking the handle as the | |
829 | * most recently used. Currently, it is done by a call to the | |
830 | * track/untrack helpers, but it should be done atomically. | |
831 | * | |
832 | * Note that the lock's nesting order must still be respected here. | |
833 | * The handle's lock nests inside the tracker's lock. | |
834 | */ | |
835 | pthread_mutex_lock(&handle->tracker->lock); | |
836 | pthread_mutex_lock(&handle->lock); | |
837 | assert(!handle->in_use); | |
838 | ||
839 | handle->tracker->stats.uses++; | |
840 | if (handle->fd >= 0) { | |
841 | ret = handle->fd; | |
842 | /* Mark as most recently used. */ | |
843 | fd_tracker_untrack(handle->tracker, handle); | |
844 | fd_tracker_track(handle->tracker, handle); | |
845 | } else { | |
846 | handle->tracker->stats.misses++; | |
847 | ret = fd_tracker_restore_handle(handle->tracker, handle); | |
848 | if (ret < 0) { | |
849 | handle->tracker->stats.errors++; | |
850 | goto end; | |
851 | } | |
852 | } | |
853 | handle->in_use = true; | |
854 | end: | |
855 | pthread_mutex_unlock(&handle->lock); | |
856 | pthread_mutex_unlock(&handle->tracker->lock); | |
857 | return ret; | |
858 | } | |
859 | ||
f5ea0241 | 860 | static void fs_handle_tracked_put_fd(struct fs_handle *_handle) |
df038819 | 861 | { |
f5ea0241 JG |
862 | struct fs_handle_tracked *handle = |
863 | container_of(_handle, struct fs_handle_tracked, parent); | |
864 | ||
df038819 JG |
865 | pthread_mutex_lock(&handle->lock); |
866 | handle->in_use = false; | |
867 | pthread_mutex_unlock(&handle->lock); | |
868 | } | |
869 | ||
f5ea0241 | 870 | static int fs_handle_tracked_unlink(struct fs_handle *_handle) |
9d16fc7f JG |
871 | { |
872 | int ret; | |
f5ea0241 JG |
873 | struct fs_handle_tracked *handle = |
874 | container_of(_handle, struct fs_handle_tracked, parent); | |
9d16fc7f JG |
875 | |
876 | pthread_mutex_lock(&handle->tracker->lock); | |
877 | pthread_mutex_lock(&handle->lock); | |
f7c3ffd7 | 878 | ret = lttng_inode_unlink(handle->inode); |
9d16fc7f JG |
879 | pthread_mutex_unlock(&handle->lock); |
880 | pthread_mutex_unlock(&handle->tracker->lock); | |
881 | return ret; | |
882 | } | |
883 | ||
f5ea0241 | 884 | static int fs_handle_tracked_close(struct fs_handle *_handle) |
df038819 JG |
885 | { |
886 | int ret = 0; | |
660a216c | 887 | const char *path = NULL; |
f5ea0241 JG |
888 | struct fs_handle_tracked *handle = |
889 | container_of(_handle, struct fs_handle_tracked, parent); | |
dd95933f | 890 | struct lttng_directory_handle *inode_directory_handle = NULL; |
df038819 JG |
891 | |
892 | if (!handle) { | |
893 | ret = -EINVAL; | |
894 | goto end; | |
895 | } | |
896 | ||
897 | pthread_mutex_lock(&handle->tracker->lock); | |
898 | pthread_mutex_lock(&handle->lock); | |
660a216c | 899 | if (handle->inode) { |
dd95933f JG |
900 | lttng_inode_borrow_location(handle->inode, NULL, &path); |
901 | /* | |
902 | * Here a reference to the inode's directory handle is acquired | |
903 | * to prevent the last reference to it from being released while | |
904 | * the tracker's lock is taken. | |
905 | * | |
906 | * If this wasn't done, the directory handle could attempt to | |
907 | * close its underlying directory file descriptor, which would | |
908 | * attempt to lock the tracker's lock, resulting in a deadlock. | |
909 | * | |
910 | * Since a new reference to the directory handle is taken within | |
911 | * the scope of this function, it is not possible for the last | |
912 | * reference to the inode's location directory handle to be | |
913 | * released during the call to lttng_inode_put(). | |
914 | * | |
915 | * We wait until the tracker's lock is released to release the | |
916 | * reference. Hence, the call to the tracker is delayed just | |
917 | * enough to not attempt to recursively acquire the tracker's | |
918 | * lock twice. | |
919 | */ | |
920 | inode_directory_handle = | |
921 | lttng_inode_get_location_directory_handle( | |
922 | handle->inode); | |
660a216c | 923 | } |
df038819 JG |
924 | fd_tracker_untrack(handle->tracker, handle); |
925 | if (handle->fd >= 0) { | |
926 | /* | |
927 | * The return value of close() is not propagated as there | |
928 | * isn't much the user can do about it. | |
929 | */ | |
930 | if (close(handle->fd)) { | |
931 | PERROR("Failed to close the file descritptor (%d) of fs handle to %s, close() returned", | |
660a216c | 932 | handle->fd, path ? path : "Unknown"); |
df038819 JG |
933 | } |
934 | handle->fd = -1; | |
935 | } | |
4c372c54 JG |
936 | if (handle->inode) { |
937 | lttng_inode_put(handle->inode); | |
938 | } | |
df038819 JG |
939 | pthread_mutex_unlock(&handle->lock); |
940 | pthread_mutex_destroy(&handle->lock); | |
941 | pthread_mutex_unlock(&handle->tracker->lock); | |
df038819 | 942 | free(handle); |
dd95933f | 943 | lttng_directory_handle_put(inode_directory_handle); |
df038819 JG |
944 | end: |
945 | return ret; | |
946 | } |