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