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 | ||
28ab034a JG |
8 | #include "fd-tracker.hpp" |
9 | #include "inode.hpp" | |
df038819 | 10 | |
c9e313bc SM |
11 | #include <common/defaults.hpp> |
12 | #include <common/error.hpp> | |
13 | #include <common/fs-handle-internal.hpp> | |
14 | #include <common/hashtable/hashtable.hpp> | |
15 | #include <common/hashtable/utils.hpp> | |
16 | #include <common/macros.hpp> | |
17 | #include <common/optional.hpp> | |
18 | ||
28ab034a JG |
19 | #include <fcntl.h> |
20 | #include <inttypes.h> | |
21 | #include <pthread.h> | |
22 | #include <stdbool.h> | |
23 | #include <sys/stat.h> | |
24 | #include <sys/types.h> | |
25 | #include <urcu.h> | |
26 | #include <urcu/list.h> | |
27 | #include <urcu/rculfhash.h> | |
df038819 JG |
28 | |
29 | /* Tracker lock must be taken by the user. */ | |
5c7248cd JG |
30 | #define TRACKED_COUNT(tracker) \ |
31 | ((tracker)->count.suspendable.active + (tracker)->count.suspendable.suspended + \ | |
32 | (tracker)->count.unsuspendable) | |
df038819 JG |
33 | |
34 | /* Tracker lock must be taken by the user. */ | |
5c7248cd | 35 | #define ACTIVE_COUNT(tracker) ((tracker)->count.suspendable.active + (tracker)->count.unsuspendable) |
df038819 JG |
36 | |
37 | /* Tracker lock must be taken by the user. */ | |
5c7248cd | 38 | #define SUSPENDED_COUNT(tracker) ((tracker)->count.suspendable.suspended) |
df038819 JG |
39 | |
40 | /* Tracker lock must be taken by the user. */ | |
28ab034a | 41 | #define SUSPENDABLE_COUNT(tracker) \ |
5c7248cd | 42 | ((tracker)->count.suspendable.active + (tracker)->count.suspendable.suspended) |
df038819 JG |
43 | |
44 | /* Tracker lock must be taken by the user. */ | |
5c7248cd | 45 | #define UNSUSPENDABLE_COUNT(tracker) ((tracker)->count.unsuspendable) |
df038819 JG |
46 | |
47 | struct fd_tracker { | |
48 | pthread_mutex_t lock; | |
49 | struct { | |
5c1f54d1 | 50 | struct { |
df038819 JG |
51 | unsigned int active; |
52 | unsigned int suspended; | |
53 | } suspendable; | |
54 | unsigned int unsuspendable; | |
55 | } count; | |
56 | unsigned int capacity; | |
57 | struct { | |
58 | uint64_t uses; | |
59 | uint64_t misses; | |
60 | /* Failures to suspend or restore fs handles. */ | |
61 | uint64_t errors; | |
62 | } stats; | |
63 | /* | |
64 | * The head of the active_handles list is always the least recently | |
65 | * used active handle. When an handle is used, it is removed from the | |
66 | * list and added to the end. When a file has to be suspended, the | |
67 | * first element in the list is "popped", suspended, and added to the | |
68 | * list of suspended handles. | |
69 | */ | |
70 | struct cds_list_head active_handles; | |
71 | struct cds_list_head suspended_handles; | |
72 | struct cds_lfht *unsuspendable_fds; | |
874a3441 | 73 | struct lttng_inode_registry *inode_registry; |
f7c3ffd7 JG |
74 | /* Unlinked files are moved in this directory under a unique name. */ |
75 | struct lttng_directory_handle *unlink_directory_handle; | |
76 | struct lttng_unlinked_file_pool *unlinked_file_pool; | |
df038819 JG |
77 | }; |
78 | ||
f1494934 | 79 | namespace { |
df038819 | 80 | struct open_properties { |
df038819 | 81 | int flags; |
1e4f5625 | 82 | LTTNG_OPTIONAL(mode_t) mode; |
df038819 JG |
83 | }; |
84 | ||
85 | /* | |
f5ea0241 | 86 | * A fs_handle_tracked is not ref-counted. Therefore, it is assumed that a |
df038819 JG |
87 | * handle is never in-use while it is being reclaimed. It can be |
88 | * shared by multiple threads, but external synchronization is required | |
89 | * to ensure it is not still being used when it is reclaimed (close method). | |
90 | * In this respect, it is not different from a regular file descriptor. | |
91 | * | |
92 | * The fs_handle lock always nests _within_ the tracker's lock. | |
93 | */ | |
f5ea0241 JG |
94 | struct fs_handle_tracked { |
95 | struct fs_handle parent; | |
df038819 JG |
96 | pthread_mutex_t lock; |
97 | /* | |
98 | * Weak reference to the tracker. All fs_handles are assumed to have | |
99 | * been closed at the moment of the destruction of the fd_tracker. | |
100 | */ | |
101 | struct fd_tracker *tracker; | |
102 | struct open_properties properties; | |
874a3441 | 103 | struct lttng_inode *inode; |
df038819 JG |
104 | int fd; |
105 | /* inode number of the file at the time of the handle's creation. */ | |
106 | uint64_t ino; | |
107 | bool in_use; | |
108 | /* Offset to which the file should be restored. */ | |
109 | off_t offset; | |
110 | struct cds_list_head handles_list_node; | |
111 | }; | |
112 | ||
113 | struct unsuspendable_fd { | |
114 | /* | |
115 | * Accesses are only performed through the tracker, which is protected | |
116 | * by its own lock. | |
117 | */ | |
118 | int fd; | |
119 | char *name; | |
120 | struct cds_lfht_node tracker_node; | |
121 | struct rcu_head rcu_head; | |
122 | }; | |
123 | ||
f1494934 | 124 | struct { |
df038819 JG |
125 | pthread_mutex_t lock; |
126 | bool initialized; | |
127 | unsigned long value; | |
128 | } seed = { | |
129 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
1c9a0b0e MJ |
130 | .initialized = false, |
131 | .value = 0, | |
df038819 | 132 | }; |
f1494934 | 133 | } /* namespace */ |
df038819 JG |
134 | |
135 | static int match_fd(struct cds_lfht_node *node, const void *key); | |
136 | static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry); | |
28ab034a | 137 | static struct unsuspendable_fd *unsuspendable_fd_create(const char *name, int fd); |
f7c3ffd7 | 138 | static int open_from_properties(const struct lttng_directory_handle *dir_handle, |
28ab034a JG |
139 | const char *path, |
140 | 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 | |
28ab034a JG |
150 | static void fd_tracker_track(struct fd_tracker *tracker, struct fs_handle_tracked *handle); |
151 | static void fd_tracker_untrack(struct fd_tracker *tracker, struct fs_handle_tracked *handle); | |
152 | static int fd_tracker_suspend_handles(struct fd_tracker *tracker, unsigned int count); | |
153 | static int fd_tracker_restore_handle(struct fd_tracker *tracker, struct fs_handle_tracked *handle); | |
f5ea0241 | 154 | |
df038819 | 155 | /* Match function of the tracker's unsuspendable_fds hash table. */ |
5c1f54d1 | 156 | static int match_fd(struct cds_lfht_node *node, const void *key) |
df038819 | 157 | { |
28ab034a JG |
158 | struct unsuspendable_fd *entry = |
159 | lttng::utils::container_of(node, &unsuspendable_fd::tracker_node); | |
df038819 | 160 | |
28ab034a | 161 | return hash_match_key_ulong((void *) (unsigned long) entry->fd, (void *) key); |
df038819 JG |
162 | } |
163 | ||
5c1f54d1 | 164 | static void delete_unsuspendable_fd(struct rcu_head *head) |
df038819 | 165 | { |
28ab034a | 166 | struct unsuspendable_fd *fd = caa_container_of(head, struct unsuspendable_fd, rcu_head); |
df038819 JG |
167 | |
168 | free(fd->name); | |
169 | free(fd); | |
170 | } | |
171 | ||
5c1f54d1 | 172 | static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry) |
df038819 JG |
173 | { |
174 | if (!entry) { | |
175 | return; | |
176 | } | |
177 | call_rcu(&entry->rcu_head, delete_unsuspendable_fd); | |
178 | } | |
179 | ||
28ab034a | 180 | static struct unsuspendable_fd *unsuspendable_fd_create(const char *name, int fd) |
df038819 | 181 | { |
64803277 | 182 | struct unsuspendable_fd *entry = zmalloc<unsuspendable_fd>(); |
df038819 JG |
183 | |
184 | if (!entry) { | |
185 | goto error; | |
186 | } | |
187 | if (name) { | |
188 | entry->name = strdup(name); | |
189 | if (!entry->name) { | |
190 | goto error; | |
191 | } | |
192 | } | |
193 | cds_lfht_node_init(&entry->tracker_node); | |
194 | entry->fd = fd; | |
195 | return entry; | |
196 | error: | |
197 | unsuspendable_fd_destroy(entry); | |
cd9adb8b | 198 | return nullptr; |
df038819 JG |
199 | } |
200 | ||
f5ea0241 | 201 | static void fs_handle_tracked_log(struct fs_handle_tracked *handle) |
df038819 | 202 | { |
874a3441 JG |
203 | const char *path; |
204 | ||
df038819 | 205 | pthread_mutex_lock(&handle->lock); |
cd9adb8b | 206 | lttng_inode_borrow_location(handle->inode, nullptr, &path); |
874a3441 | 207 | |
df038819 | 208 | if (handle->fd >= 0) { |
28ab034a JG |
209 | DBG_NO_LOC(" %s [active, fd %d%s]", |
210 | path, | |
211 | handle->fd, | |
212 | handle->in_use ? ", in use" : ""); | |
df038819 | 213 | } else { |
874a3441 | 214 | DBG_NO_LOC(" %s [suspended]", path); |
df038819 JG |
215 | } |
216 | pthread_mutex_unlock(&handle->lock); | |
217 | } | |
218 | ||
874a3441 | 219 | /* Tracker lock must be held by the caller. */ |
f5ea0241 | 220 | static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle) |
df038819 JG |
221 | { |
222 | int ret = 0; | |
223 | struct stat fs_stat; | |
874a3441 | 224 | const char *path; |
f7c3ffd7 | 225 | const struct lttng_directory_handle *node_directory_handle; |
df038819 JG |
226 | |
227 | pthread_mutex_lock(&handle->lock); | |
28ab034a | 228 | lttng_inode_borrow_location(handle->inode, &node_directory_handle, &path); |
a0377dfe | 229 | LTTNG_ASSERT(handle->fd >= 0); |
df038819 JG |
230 | if (handle->in_use) { |
231 | /* This handle can't be suspended as it is currently in use. */ | |
232 | ret = -EAGAIN; | |
233 | goto end; | |
234 | } | |
235 | ||
28ab034a | 236 | ret = lttng_directory_handle_stat(node_directory_handle, path, &fs_stat); |
df038819 | 237 | if (ret) { |
28ab034a | 238 | PERROR("Filesystem handle to %s cannot be suspended as stat() failed", path); |
df038819 JG |
239 | ret = -errno; |
240 | goto end; | |
241 | } | |
242 | ||
243 | if (fs_stat.st_ino != handle->ino) { | |
244 | /* Don't suspend as the handle would not be restorable. */ | |
28ab034a | 245 | WARN("Filesystem handle to %s cannot be suspended as its inode changed", path); |
df038819 JG |
246 | ret = -ENOENT; |
247 | goto end; | |
248 | } | |
249 | ||
5c1f54d1 | 250 | handle->offset = lseek(handle->fd, 0, SEEK_CUR); |
df038819 JG |
251 | if (handle->offset == -1) { |
252 | WARN("Filesystem handle to %s cannot be suspended as lseek() failed to sample its current position", | |
28ab034a | 253 | path); |
df038819 JG |
254 | ret = -errno; |
255 | goto end; | |
256 | } | |
257 | ||
258 | ret = close(handle->fd); | |
259 | if (ret) { | |
28ab034a | 260 | PERROR("Filesystem handle to %s cannot be suspended as close() failed", path); |
df038819 JG |
261 | ret = -errno; |
262 | goto end; | |
263 | } | |
264 | DBG("Suspended filesystem handle to %s (fd %i) at position %" PRId64, | |
28ab034a JG |
265 | path, |
266 | handle->fd, | |
267 | handle->offset); | |
df038819 JG |
268 | handle->fd = -1; |
269 | end: | |
270 | if (ret) { | |
271 | handle->tracker->stats.errors++; | |
272 | } | |
273 | pthread_mutex_unlock(&handle->lock); | |
274 | return ret; | |
275 | } | |
276 | ||
277 | /* Caller must hold the tracker and handle's locks. */ | |
f5ea0241 | 278 | static int fs_handle_tracked_restore(struct fs_handle_tracked *handle) |
df038819 JG |
279 | { |
280 | int ret, fd = -1; | |
f7c3ffd7 JG |
281 | const char *path; |
282 | const struct lttng_directory_handle *node_directory_handle; | |
283 | ||
28ab034a | 284 | lttng_inode_borrow_location(handle->inode, &node_directory_handle, &path); |
df038819 | 285 | |
a0377dfe FD |
286 | LTTNG_ASSERT(handle->fd == -1); |
287 | LTTNG_ASSERT(path); | |
28ab034a | 288 | ret = open_from_properties(node_directory_handle, path, &handle->properties); |
df038819 | 289 | if (ret < 0) { |
28ab034a | 290 | PERROR("Failed to restore filesystem handle to %s, open() failed", path); |
df038819 JG |
291 | ret = -errno; |
292 | goto end; | |
293 | } | |
294 | fd = ret; | |
295 | ||
296 | ret = lseek(fd, handle->offset, SEEK_SET); | |
297 | if (ret < 0) { | |
28ab034a | 298 | PERROR("Failed to restore filesystem handle to %s, lseek() failed", path); |
df038819 JG |
299 | ret = -errno; |
300 | goto end; | |
301 | } | |
302 | DBG("Restored filesystem handle to %s (fd %i) at position %" PRId64, | |
28ab034a JG |
303 | path, |
304 | fd, | |
305 | handle->offset); | |
df038819 JG |
306 | ret = 0; |
307 | handle->fd = fd; | |
308 | fd = -1; | |
309 | end: | |
310 | if (fd >= 0) { | |
311 | (void) close(fd); | |
312 | } | |
313 | return ret; | |
314 | } | |
315 | ||
f7c3ffd7 | 316 | static int open_from_properties(const struct lttng_directory_handle *dir_handle, |
28ab034a JG |
317 | const char *path, |
318 | struct open_properties *properties) | |
df038819 JG |
319 | { |
320 | int ret; | |
321 | ||
322 | /* | |
323 | * open() ignores the 'flags' parameter unless the O_CREAT or O_TMPFILE | |
324 | * flags are set. O_TMPFILE would not make sense in the context of a | |
325 | * suspendable fs_handle as it would not be restorable (see OPEN(2)), | |
326 | * thus it is ignored here. | |
327 | */ | |
328 | if ((properties->flags & O_CREAT) && properties->mode.is_set) { | |
28ab034a JG |
329 | ret = lttng_directory_handle_open_file( |
330 | dir_handle, path, properties->flags, properties->mode.value); | |
df038819 | 331 | } else { |
28ab034a | 332 | ret = lttng_directory_handle_open_file(dir_handle, path, properties->flags, 0); |
df038819 JG |
333 | } |
334 | /* | |
335 | * Some flags should not be used beyond the initial open() of a | |
336 | * restorable file system handle. O_CREAT and O_TRUNC must | |
337 | * be cleared since it would be unexpected to re-use them | |
338 | * when the handle is retored: | |
339 | * - O_CREAT should not be needed as the file has been created | |
340 | * on the initial call to open(), | |
341 | * - O_TRUNC would destroy the file's contents by truncating it | |
342 | * to length 0. | |
343 | */ | |
344 | properties->flags &= ~(O_CREAT | O_TRUNC); | |
345 | if (ret < 0) { | |
346 | ret = -errno; | |
347 | goto end; | |
348 | } | |
349 | end: | |
350 | return ret; | |
351 | } | |
352 | ||
28ab034a | 353 | struct fd_tracker *fd_tracker_create(const char *unlinked_file_path, unsigned int capacity) |
df038819 | 354 | { |
64803277 | 355 | struct fd_tracker *tracker = zmalloc<fd_tracker>(); |
df038819 JG |
356 | |
357 | if (!tracker) { | |
358 | goto end; | |
359 | } | |
360 | ||
361 | pthread_mutex_lock(&seed.lock); | |
362 | if (!seed.initialized) { | |
cd9adb8b | 363 | seed.value = (unsigned long) time(nullptr); |
df038819 JG |
364 | seed.initialized = true; |
365 | } | |
366 | pthread_mutex_unlock(&seed.lock); | |
367 | ||
368 | CDS_INIT_LIST_HEAD(&tracker->active_handles); | |
369 | CDS_INIT_LIST_HEAD(&tracker->suspended_handles); | |
370 | tracker->capacity = capacity; | |
28ab034a | 371 | tracker->unsuspendable_fds = cds_lfht_new( |
cd9adb8b | 372 | DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, nullptr); |
874a3441 JG |
373 | if (!tracker->unsuspendable_fds) { |
374 | ERR("Failed to create fd-tracker's unsuspendable_fds hash table"); | |
375 | goto error; | |
376 | } | |
377 | tracker->inode_registry = lttng_inode_registry_create(); | |
378 | if (!tracker->inode_registry) { | |
379 | ERR("Failed to create fd-tracker's inode registry"); | |
380 | goto error; | |
381 | } | |
f7c3ffd7 | 382 | |
28ab034a | 383 | tracker->unlinked_file_pool = lttng_unlinked_file_pool_create(unlinked_file_path); |
f7c3ffd7 JG |
384 | if (!tracker->unlinked_file_pool) { |
385 | goto error; | |
386 | } | |
df038819 | 387 | DBG("File descriptor tracker created with a limit of %u simultaneously-opened FDs", |
28ab034a | 388 | capacity); |
df038819 JG |
389 | end: |
390 | return tracker; | |
874a3441 JG |
391 | error: |
392 | fd_tracker_destroy(tracker); | |
cd9adb8b | 393 | return nullptr; |
df038819 JG |
394 | } |
395 | ||
396 | void fd_tracker_log(struct fd_tracker *tracker) | |
397 | { | |
f5ea0241 | 398 | struct fs_handle_tracked *handle; |
df038819 JG |
399 | struct unsuspendable_fd *unsuspendable_fd; |
400 | struct cds_lfht_iter iter; | |
401 | ||
402 | pthread_mutex_lock(&tracker->lock); | |
403 | DBG_NO_LOC("File descriptor tracker"); | |
404 | DBG_NO_LOC(" Stats:"); | |
405 | DBG_NO_LOC(" uses: %" PRIu64, tracker->stats.uses); | |
406 | DBG_NO_LOC(" misses: %" PRIu64, tracker->stats.misses); | |
407 | DBG_NO_LOC(" errors: %" PRIu64, tracker->stats.errors); | |
408 | DBG_NO_LOC(" Tracked: %u", TRACKED_COUNT(tracker)); | |
409 | DBG_NO_LOC(" active: %u", ACTIVE_COUNT(tracker)); | |
410 | DBG_NO_LOC(" suspendable: %u", SUSPENDABLE_COUNT(tracker)); | |
411 | DBG_NO_LOC(" unsuspendable: %u", UNSUSPENDABLE_COUNT(tracker)); | |
412 | DBG_NO_LOC(" suspended: %u", SUSPENDED_COUNT(tracker)); | |
413 | DBG_NO_LOC(" capacity: %u", tracker->capacity); | |
414 | ||
415 | DBG_NO_LOC(" Tracked suspendable file descriptors"); | |
28ab034a | 416 | cds_list_for_each_entry (handle, &tracker->active_handles, handles_list_node) { |
f5ea0241 | 417 | fs_handle_tracked_log(handle); |
df038819 | 418 | } |
28ab034a | 419 | cds_list_for_each_entry (handle, &tracker->suspended_handles, handles_list_node) { |
f5ea0241 | 420 | fs_handle_tracked_log(handle); |
df038819 JG |
421 | } |
422 | if (!SUSPENDABLE_COUNT(tracker)) { | |
423 | DBG_NO_LOC(" None"); | |
424 | } | |
425 | ||
426 | DBG_NO_LOC(" Tracked unsuspendable file descriptors"); | |
427 | rcu_read_lock(); | |
28ab034a JG |
428 | cds_lfht_for_each_entry ( |
429 | tracker->unsuspendable_fds, &iter, unsuspendable_fd, tracker_node) { | |
5c1f54d1 | 430 | DBG_NO_LOC(" %s [active, fd %d]", |
28ab034a JG |
431 | unsuspendable_fd->name ?: "Unnamed", |
432 | unsuspendable_fd->fd); | |
df038819 JG |
433 | } |
434 | rcu_read_unlock(); | |
435 | if (!UNSUSPENDABLE_COUNT(tracker)) { | |
436 | DBG_NO_LOC(" None"); | |
437 | } | |
438 | ||
439 | pthread_mutex_unlock(&tracker->lock); | |
440 | } | |
441 | ||
442 | int fd_tracker_destroy(struct fd_tracker *tracker) | |
443 | { | |
444 | int ret = 0; | |
445 | ||
f6bef966 JG |
446 | if (!tracker) { |
447 | goto end; | |
448 | } | |
df038819 JG |
449 | /* |
450 | * Refuse to destroy the tracker as fs_handles may still old | |
451 | * weak references to the tracker. | |
452 | */ | |
453 | pthread_mutex_lock(&tracker->lock); | |
454 | if (TRACKED_COUNT(tracker)) { | |
455 | ERR("A file descriptor leak has been detected: %u tracked file descriptors are still being tracked", | |
28ab034a | 456 | TRACKED_COUNT(tracker)); |
df038819 JG |
457 | pthread_mutex_unlock(&tracker->lock); |
458 | fd_tracker_log(tracker); | |
459 | ret = -1; | |
460 | goto end; | |
461 | } | |
462 | pthread_mutex_unlock(&tracker->lock); | |
463 | ||
874a3441 | 464 | if (tracker->unsuspendable_fds) { |
cd9adb8b | 465 | ret = cds_lfht_destroy(tracker->unsuspendable_fds, nullptr); |
a0377dfe | 466 | LTTNG_ASSERT(!ret); |
874a3441 | 467 | } |
660a216c JG |
468 | |
469 | lttng_inode_registry_destroy(tracker->inode_registry); | |
f7c3ffd7 | 470 | lttng_unlinked_file_pool_destroy(tracker->unlinked_file_pool); |
df038819 JG |
471 | pthread_mutex_destroy(&tracker->lock); |
472 | free(tracker); | |
473 | end: | |
474 | return ret; | |
475 | } | |
476 | ||
477 | struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, | |
28ab034a JG |
478 | struct lttng_directory_handle *directory, |
479 | const char *path, | |
480 | int flags, | |
481 | mode_t *mode) | |
df038819 JG |
482 | { |
483 | int ret; | |
cd9adb8b | 484 | struct fs_handle_tracked *handle = nullptr; |
df038819 | 485 | struct stat fd_stat; |
28ab034a JG |
486 | struct open_properties properties = { .flags = flags, |
487 | .mode = { | |
488 | .is_set = !!mode, | |
489 | .value = | |
490 | static_cast<mode_t>(mode ? *mode : 0), | |
491 | } }; | |
df038819 | 492 | |
df038819 JG |
493 | pthread_mutex_lock(&tracker->lock); |
494 | if (ACTIVE_COUNT(tracker) == tracker->capacity) { | |
495 | if (tracker->count.suspendable.active > 0) { | |
496 | ret = fd_tracker_suspend_handles(tracker, 1); | |
497 | if (ret) { | |
19380ea8 | 498 | goto end; |
df038819 JG |
499 | } |
500 | } else { | |
501 | /* | |
502 | * There are not enough active suspendable file | |
19380ea8 JG |
503 | * descriptors to open a new fd and still accommodate |
504 | * the tracker's capacity. | |
df038819 JG |
505 | */ |
506 | WARN("Cannot open file system handle, too many unsuspendable file descriptors are opened (%u)", | |
28ab034a | 507 | tracker->count.unsuspendable); |
19380ea8 | 508 | goto end; |
df038819 JG |
509 | } |
510 | } | |
511 | ||
64803277 | 512 | handle = zmalloc<fs_handle_tracked>(); |
df038819 JG |
513 | if (!handle) { |
514 | goto end; | |
515 | } | |
28ab034a | 516 | handle->parent = (typeof(handle->parent)){ |
f7c3ffd7 JG |
517 | .get_fd = fs_handle_tracked_get_fd, |
518 | .put_fd = fs_handle_tracked_put_fd, | |
519 | .unlink = fs_handle_tracked_unlink, | |
520 | .close = fs_handle_tracked_close, | |
521 | }; | |
522 | ||
660a216c | 523 | handle->tracker = tracker; |
df038819 | 524 | |
cd9adb8b | 525 | ret = pthread_mutex_init(&handle->lock, nullptr); |
df038819 JG |
526 | if (ret) { |
527 | PERROR("Failed to initialize handle mutex while creating fs handle"); | |
19380ea8 | 528 | goto error_mutex_init; |
df038819 JG |
529 | } |
530 | ||
f7c3ffd7 | 531 | handle->fd = open_from_properties(directory, path, &properties); |
df038819 JG |
532 | if (handle->fd < 0) { |
533 | PERROR("Failed to open fs handle to %s, open() returned", path); | |
19380ea8 | 534 | goto error; |
df038819 JG |
535 | } |
536 | ||
537 | handle->properties = properties; | |
874a3441 | 538 | |
28ab034a JG |
539 | handle->inode = lttng_inode_registry_get_inode( |
540 | tracker->inode_registry, directory, path, handle->fd, tracker->unlinked_file_pool); | |
874a3441 | 541 | if (!handle->inode) { |
5c1f54d1 | 542 | ERR("Failed to get lttng_inode corresponding to file %s", path); |
19380ea8 | 543 | goto error; |
874a3441 | 544 | } |
df038819 JG |
545 | |
546 | if (fstat(handle->fd, &fd_stat)) { | |
547 | PERROR("Failed to retrieve file descriptor inode while creating fs handle, fstat() returned"); | |
19380ea8 | 548 | goto error; |
df038819 JG |
549 | } |
550 | handle->ino = fd_stat.st_ino; | |
551 | ||
552 | fd_tracker_track(tracker, handle); | |
df038819 | 553 | end: |
19380ea8 | 554 | pthread_mutex_unlock(&tracker->lock); |
cd9adb8b | 555 | return handle ? &handle->parent : nullptr; |
19380ea8 | 556 | error: |
660a216c JG |
557 | if (handle->inode) { |
558 | lttng_inode_put(handle->inode); | |
559 | } | |
19380ea8 JG |
560 | pthread_mutex_destroy(&handle->lock); |
561 | error_mutex_init: | |
660a216c | 562 | free(handle); |
cd9adb8b | 563 | handle = nullptr; |
df038819 JG |
564 | goto end; |
565 | } | |
566 | ||
567 | /* Caller must hold the tracker's lock. */ | |
28ab034a | 568 | static int fd_tracker_suspend_handles(struct fd_tracker *tracker, unsigned int count) |
df038819 JG |
569 | { |
570 | unsigned int left_to_close = count; | |
f7c3ffd7 | 571 | unsigned int attempts_left = tracker->count.suspendable.active; |
f5ea0241 | 572 | struct fs_handle_tracked *handle, *tmp; |
df038819 | 573 | |
28ab034a | 574 | cds_list_for_each_entry_safe (handle, tmp, &tracker->active_handles, handles_list_node) { |
df038819 JG |
575 | int ret; |
576 | ||
577 | fd_tracker_untrack(tracker, handle); | |
f5ea0241 | 578 | ret = fs_handle_tracked_suspend(handle); |
df038819 JG |
579 | fd_tracker_track(tracker, handle); |
580 | if (!ret) { | |
581 | left_to_close--; | |
582 | } | |
f7c3ffd7 | 583 | attempts_left--; |
df038819 | 584 | |
f7c3ffd7 | 585 | if (left_to_close == 0 || attempts_left == 0) { |
df038819 JG |
586 | break; |
587 | } | |
588 | } | |
589 | return left_to_close ? -EMFILE : 0; | |
590 | } | |
591 | ||
592 | int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, | |
28ab034a JG |
593 | int *out_fds, |
594 | const char **names, | |
595 | unsigned int fd_count, | |
596 | fd_open_cb open, | |
597 | void *user_data) | |
df038819 JG |
598 | { |
599 | int ret, user_ret, i, fds_to_suspend; | |
600 | unsigned int active_fds; | |
b13a2b17 | 601 | struct unsuspendable_fd **entries; |
df038819 | 602 | |
64803277 | 603 | entries = calloc<unsuspendable_fd *>(fd_count); |
b13a2b17 JG |
604 | if (!entries) { |
605 | ret = -1; | |
606 | goto end; | |
607 | } | |
df038819 JG |
608 | |
609 | pthread_mutex_lock(&tracker->lock); | |
610 | ||
611 | active_fds = ACTIVE_COUNT(tracker); | |
28ab034a | 612 | fds_to_suspend = (int) active_fds + (int) fd_count - (int) tracker->capacity; |
df038819 JG |
613 | if (fds_to_suspend > 0) { |
614 | if (fds_to_suspend <= tracker->count.suspendable.active) { | |
28ab034a | 615 | ret = fd_tracker_suspend_handles(tracker, fds_to_suspend); |
df038819 | 616 | if (ret) { |
b13a2b17 | 617 | goto end_unlock; |
df038819 JG |
618 | } |
619 | } else { | |
620 | /* | |
621 | * There are not enough active suspendable file | |
d49487dc | 622 | * descriptors to open a new fd and still accommodates the |
df038819 JG |
623 | * tracker's capacity. |
624 | */ | |
625 | WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)", | |
28ab034a | 626 | tracker->count.unsuspendable); |
df038819 | 627 | ret = -EMFILE; |
b13a2b17 | 628 | goto end_unlock; |
df038819 JG |
629 | } |
630 | } | |
631 | ||
632 | user_ret = open(user_data, out_fds); | |
633 | if (user_ret) { | |
634 | ret = user_ret; | |
b13a2b17 | 635 | goto end_unlock; |
df038819 JG |
636 | } |
637 | ||
638 | /* | |
639 | * Add the fds returned by the user's callback to the hashtable | |
640 | * of unsuspendable fds. | |
641 | */ | |
642 | for (i = 0; i < fd_count; i++) { | |
28ab034a | 643 | struct unsuspendable_fd *entry = |
cd9adb8b | 644 | unsuspendable_fd_create(names ? names[i] : nullptr, out_fds[i]); |
df038819 JG |
645 | |
646 | if (!entry) { | |
647 | ret = -1; | |
648 | goto end_free_entries; | |
649 | } | |
650 | entries[i] = entry; | |
651 | } | |
652 | ||
653 | rcu_read_lock(); | |
654 | for (i = 0; i < fd_count; i++) { | |
655 | struct cds_lfht_node *node; | |
656 | struct unsuspendable_fd *entry = entries[i]; | |
657 | ||
5c1f54d1 | 658 | node = cds_lfht_add_unique(tracker->unsuspendable_fds, |
28ab034a JG |
659 | hash_key_ulong((void *) (unsigned long) out_fds[i], |
660 | seed.value), | |
661 | match_fd, | |
662 | (void *) (unsigned long) out_fds[i], | |
663 | &entry->tracker_node); | |
df038819 JG |
664 | |
665 | if (node != &entry->tracker_node) { | |
666 | ret = -EEXIST; | |
667 | rcu_read_unlock(); | |
668 | goto end_free_entries; | |
669 | } | |
cd9adb8b | 670 | entries[i] = nullptr; |
df038819 JG |
671 | } |
672 | tracker->count.unsuspendable += fd_count; | |
673 | rcu_read_unlock(); | |
674 | ret = user_ret; | |
b13a2b17 | 675 | end_unlock: |
df038819 | 676 | pthread_mutex_unlock(&tracker->lock); |
b13a2b17 JG |
677 | end: |
678 | free(entries); | |
df038819 JG |
679 | return ret; |
680 | end_free_entries: | |
681 | for (i = 0; i < fd_count; i++) { | |
682 | unsuspendable_fd_destroy(entries[i]); | |
683 | } | |
b13a2b17 | 684 | goto end_unlock; |
df038819 JG |
685 | } |
686 | ||
687 | int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, | |
28ab034a JG |
688 | int *fds_in, |
689 | unsigned int fd_count, | |
690 | fd_close_cb close, | |
691 | void *user_data) | |
df038819 JG |
692 | { |
693 | int i, ret, user_ret; | |
cd9adb8b | 694 | int *fds = nullptr; |
df038819 JG |
695 | |
696 | /* | |
697 | * Maintain a local copy of fds_in as the user's callback may modify its | |
698 | * contents (e.g. setting the fd(s) to -1 after close). | |
699 | */ | |
64803277 | 700 | fds = malloc<int>(sizeof(*fds) * fd_count); |
b13a2b17 JG |
701 | if (!fds) { |
702 | ret = -1; | |
703 | goto end; | |
704 | } | |
df038819 JG |
705 | memcpy(fds, fds_in, sizeof(*fds) * fd_count); |
706 | ||
707 | pthread_mutex_lock(&tracker->lock); | |
708 | rcu_read_lock(); | |
709 | ||
710 | /* Let the user close the file descriptors. */ | |
711 | user_ret = close(user_data, fds_in); | |
712 | if (user_ret) { | |
713 | ret = user_ret; | |
b13a2b17 | 714 | goto end_unlock; |
df038819 JG |
715 | } |
716 | ||
717 | /* Untrack the fds that were just closed by the user's callback. */ | |
718 | for (i = 0; i < fd_count; i++) { | |
719 | struct cds_lfht_node *node; | |
720 | struct cds_lfht_iter iter; | |
721 | struct unsuspendable_fd *entry; | |
722 | ||
723 | cds_lfht_lookup(tracker->unsuspendable_fds, | |
28ab034a JG |
724 | hash_key_ulong((void *) (unsigned long) fds[i], seed.value), |
725 | match_fd, | |
726 | (void *) (unsigned long) fds[i], | |
df038819 JG |
727 | &iter); |
728 | node = cds_lfht_iter_get_node(&iter); | |
729 | if (!node) { | |
730 | /* Unknown file descriptor. */ | |
731 | WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()", | |
28ab034a | 732 | fds[i]); |
df038819 | 733 | ret = -EINVAL; |
b13a2b17 | 734 | goto end_unlock; |
df038819 | 735 | } |
28ab034a | 736 | entry = lttng::utils::container_of(node, &unsuspendable_fd::tracker_node); |
df038819 JG |
737 | |
738 | cds_lfht_del(tracker->unsuspendable_fds, node); | |
739 | unsuspendable_fd_destroy(entry); | |
740 | fds[i] = -1; | |
741 | } | |
742 | ||
743 | tracker->count.unsuspendable -= fd_count; | |
744 | ret = 0; | |
b13a2b17 | 745 | end_unlock: |
df038819 JG |
746 | rcu_read_unlock(); |
747 | pthread_mutex_unlock(&tracker->lock); | |
b13a2b17 JG |
748 | free(fds); |
749 | end: | |
df038819 JG |
750 | return ret; |
751 | } | |
752 | ||
753 | /* Caller must have taken the tracker's and handle's locks. */ | |
28ab034a | 754 | static void fd_tracker_track(struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
755 | { |
756 | if (handle->fd >= 0) { | |
757 | tracker->count.suspendable.active++; | |
28ab034a | 758 | cds_list_add_tail(&handle->handles_list_node, &tracker->active_handles); |
df038819 JG |
759 | } else { |
760 | tracker->count.suspendable.suspended++; | |
28ab034a | 761 | cds_list_add_tail(&handle->handles_list_node, &tracker->suspended_handles); |
df038819 JG |
762 | } |
763 | } | |
764 | ||
765 | /* Caller must have taken the tracker's and handle's locks. */ | |
28ab034a | 766 | static void fd_tracker_untrack(struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
767 | { |
768 | if (handle->fd >= 0) { | |
769 | tracker->count.suspendable.active--; | |
770 | } else { | |
771 | tracker->count.suspendable.suspended--; | |
772 | } | |
773 | cds_list_del(&handle->handles_list_node); | |
774 | } | |
775 | ||
776 | /* Caller must have taken the tracker's and handle's locks. */ | |
28ab034a | 777 | static int fd_tracker_restore_handle(struct fd_tracker *tracker, struct fs_handle_tracked *handle) |
df038819 JG |
778 | { |
779 | int ret; | |
780 | ||
781 | fd_tracker_untrack(tracker, handle); | |
782 | if (ACTIVE_COUNT(tracker) >= tracker->capacity) { | |
783 | ret = fd_tracker_suspend_handles(tracker, 1); | |
784 | if (ret) { | |
785 | goto end; | |
786 | } | |
787 | } | |
f5ea0241 | 788 | ret = fs_handle_tracked_restore(handle); |
df038819 JG |
789 | end: |
790 | fd_tracker_track(tracker, handle); | |
791 | return ret ? ret : handle->fd; | |
792 | } | |
793 | ||
f5ea0241 | 794 | static int fs_handle_tracked_get_fd(struct fs_handle *_handle) |
df038819 JG |
795 | { |
796 | int ret; | |
f5ea0241 | 797 | struct fs_handle_tracked *handle = |
28ab034a | 798 | lttng::utils::container_of(_handle, &fs_handle_tracked::parent); |
df038819 JG |
799 | |
800 | /* | |
801 | * TODO This should be optimized as it is a fairly hot path. | |
802 | * The fd-tracker's lock should only be taken when a fs_handle is | |
803 | * restored (slow path). On the fast path (fs_handle is active), | |
804 | * the only effect on the fd_tracker is marking the handle as the | |
805 | * most recently used. Currently, it is done by a call to the | |
806 | * track/untrack helpers, but it should be done atomically. | |
807 | * | |
808 | * Note that the lock's nesting order must still be respected here. | |
809 | * The handle's lock nests inside the tracker's lock. | |
810 | */ | |
811 | pthread_mutex_lock(&handle->tracker->lock); | |
812 | pthread_mutex_lock(&handle->lock); | |
a0377dfe | 813 | LTTNG_ASSERT(!handle->in_use); |
df038819 JG |
814 | |
815 | handle->tracker->stats.uses++; | |
816 | if (handle->fd >= 0) { | |
817 | ret = handle->fd; | |
818 | /* Mark as most recently used. */ | |
819 | fd_tracker_untrack(handle->tracker, handle); | |
820 | fd_tracker_track(handle->tracker, handle); | |
821 | } else { | |
822 | handle->tracker->stats.misses++; | |
823 | ret = fd_tracker_restore_handle(handle->tracker, handle); | |
824 | if (ret < 0) { | |
825 | handle->tracker->stats.errors++; | |
826 | goto end; | |
827 | } | |
828 | } | |
829 | handle->in_use = true; | |
830 | end: | |
831 | pthread_mutex_unlock(&handle->lock); | |
832 | pthread_mutex_unlock(&handle->tracker->lock); | |
833 | return ret; | |
834 | } | |
835 | ||
f5ea0241 | 836 | static void fs_handle_tracked_put_fd(struct fs_handle *_handle) |
df038819 | 837 | { |
f5ea0241 | 838 | struct fs_handle_tracked *handle = |
28ab034a | 839 | lttng::utils::container_of(_handle, &fs_handle_tracked::parent); |
f5ea0241 | 840 | |
df038819 JG |
841 | pthread_mutex_lock(&handle->lock); |
842 | handle->in_use = false; | |
843 | pthread_mutex_unlock(&handle->lock); | |
844 | } | |
845 | ||
f5ea0241 | 846 | static int fs_handle_tracked_unlink(struct fs_handle *_handle) |
9d16fc7f JG |
847 | { |
848 | int ret; | |
f5ea0241 | 849 | struct fs_handle_tracked *handle = |
28ab034a | 850 | lttng::utils::container_of(_handle, &fs_handle_tracked::parent); |
9d16fc7f JG |
851 | |
852 | pthread_mutex_lock(&handle->tracker->lock); | |
853 | pthread_mutex_lock(&handle->lock); | |
f7c3ffd7 | 854 | ret = lttng_inode_unlink(handle->inode); |
9d16fc7f JG |
855 | pthread_mutex_unlock(&handle->lock); |
856 | pthread_mutex_unlock(&handle->tracker->lock); | |
857 | return ret; | |
858 | } | |
859 | ||
f5ea0241 | 860 | static int fs_handle_tracked_close(struct fs_handle *_handle) |
df038819 JG |
861 | { |
862 | int ret = 0; | |
cd9adb8b | 863 | const char *path = nullptr; |
f5ea0241 | 864 | struct fs_handle_tracked *handle = |
28ab034a | 865 | lttng::utils::container_of(_handle, &fs_handle_tracked::parent); |
cd9adb8b | 866 | struct lttng_directory_handle *inode_directory_handle = nullptr; |
df038819 JG |
867 | |
868 | if (!handle) { | |
869 | ret = -EINVAL; | |
870 | goto end; | |
871 | } | |
872 | ||
873 | pthread_mutex_lock(&handle->tracker->lock); | |
874 | pthread_mutex_lock(&handle->lock); | |
660a216c | 875 | if (handle->inode) { |
cd9adb8b | 876 | lttng_inode_borrow_location(handle->inode, nullptr, &path); |
dd95933f JG |
877 | /* |
878 | * Here a reference to the inode's directory handle is acquired | |
879 | * to prevent the last reference to it from being released while | |
880 | * the tracker's lock is taken. | |
881 | * | |
882 | * If this wasn't done, the directory handle could attempt to | |
883 | * close its underlying directory file descriptor, which would | |
884 | * attempt to lock the tracker's lock, resulting in a deadlock. | |
885 | * | |
886 | * Since a new reference to the directory handle is taken within | |
887 | * the scope of this function, it is not possible for the last | |
888 | * reference to the inode's location directory handle to be | |
889 | * released during the call to lttng_inode_put(). | |
890 | * | |
891 | * We wait until the tracker's lock is released to release the | |
892 | * reference. Hence, the call to the tracker is delayed just | |
893 | * enough to not attempt to recursively acquire the tracker's | |
894 | * lock twice. | |
895 | */ | |
28ab034a | 896 | inode_directory_handle = lttng_inode_get_location_directory_handle(handle->inode); |
660a216c | 897 | } |
df038819 JG |
898 | fd_tracker_untrack(handle->tracker, handle); |
899 | if (handle->fd >= 0) { | |
900 | /* | |
901 | * The return value of close() is not propagated as there | |
902 | * isn't much the user can do about it. | |
903 | */ | |
904 | if (close(handle->fd)) { | |
ea05fafd | 905 | PERROR("Failed to close the file descriptor (%d) of fs handle to %s, close() returned", |
28ab034a JG |
906 | handle->fd, |
907 | path ? path : "Unknown"); | |
df038819 JG |
908 | } |
909 | handle->fd = -1; | |
910 | } | |
4c372c54 JG |
911 | if (handle->inode) { |
912 | lttng_inode_put(handle->inode); | |
913 | } | |
df038819 JG |
914 | pthread_mutex_unlock(&handle->lock); |
915 | pthread_mutex_destroy(&handle->lock); | |
916 | pthread_mutex_unlock(&handle->tracker->lock); | |
df038819 | 917 | free(handle); |
dd95933f | 918 | lttng_directory_handle_put(inode_directory_handle); |
df038819 JG |
919 | end: |
920 | return ret; | |
921 | } |