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963b61eb SW |
1 | #include "ceph_debug.h" |
2 | ||
963b61eb SW |
3 | #include <linux/sort.h> |
4 | ||
5 | #include "super.h" | |
6 | #include "decode.h" | |
7 | ||
8 | /* | |
9 | * Snapshots in ceph are driven in large part by cooperation from the | |
10 | * client. In contrast to local file systems or file servers that | |
11 | * implement snapshots at a single point in the system, ceph's | |
12 | * distributed access to storage requires clients to help decide | |
13 | * whether a write logically occurs before or after a recently created | |
14 | * snapshot. | |
15 | * | |
16 | * This provides a perfect instantanous client-wide snapshot. Between | |
17 | * clients, however, snapshots may appear to be applied at slightly | |
18 | * different points in time, depending on delays in delivering the | |
19 | * snapshot notification. | |
20 | * | |
21 | * Snapshots are _not_ file system-wide. Instead, each snapshot | |
22 | * applies to the subdirectory nested beneath some directory. This | |
23 | * effectively divides the hierarchy into multiple "realms," where all | |
24 | * of the files contained by each realm share the same set of | |
25 | * snapshots. An individual realm's snap set contains snapshots | |
26 | * explicitly created on that realm, as well as any snaps in its | |
27 | * parent's snap set _after_ the point at which the parent became it's | |
28 | * parent (due to, say, a rename). Similarly, snaps from prior parents | |
29 | * during the time intervals during which they were the parent are included. | |
30 | * | |
31 | * The client is spared most of this detail, fortunately... it must only | |
32 | * maintains a hierarchy of realms reflecting the current parent/child | |
33 | * realm relationship, and for each realm has an explicit list of snaps | |
34 | * inherited from prior parents. | |
35 | * | |
36 | * A snap_realm struct is maintained for realms containing every inode | |
37 | * with an open cap in the system. (The needed snap realm information is | |
38 | * provided by the MDS whenever a cap is issued, i.e., on open.) A 'seq' | |
39 | * version number is used to ensure that as realm parameters change (new | |
40 | * snapshot, new parent, etc.) the client's realm hierarchy is updated. | |
41 | * | |
42 | * The realm hierarchy drives the generation of a 'snap context' for each | |
43 | * realm, which simply lists the resulting set of snaps for the realm. This | |
44 | * is attached to any writes sent to OSDs. | |
45 | */ | |
46 | /* | |
47 | * Unfortunately error handling is a bit mixed here. If we get a snap | |
48 | * update, but don't have enough memory to update our realm hierarchy, | |
49 | * it's not clear what we can do about it (besides complaining to the | |
50 | * console). | |
51 | */ | |
52 | ||
53 | ||
54 | /* | |
55 | * increase ref count for the realm | |
56 | * | |
57 | * caller must hold snap_rwsem for write. | |
58 | */ | |
59 | void ceph_get_snap_realm(struct ceph_mds_client *mdsc, | |
60 | struct ceph_snap_realm *realm) | |
61 | { | |
62 | dout("get_realm %p %d -> %d\n", realm, | |
63 | atomic_read(&realm->nref), atomic_read(&realm->nref)+1); | |
64 | /* | |
65 | * since we _only_ increment realm refs or empty the empty | |
66 | * list with snap_rwsem held, adjusting the empty list here is | |
67 | * safe. we do need to protect against concurrent empty list | |
68 | * additions, however. | |
69 | */ | |
70 | if (atomic_read(&realm->nref) == 0) { | |
71 | spin_lock(&mdsc->snap_empty_lock); | |
72 | list_del_init(&realm->empty_item); | |
73 | spin_unlock(&mdsc->snap_empty_lock); | |
74 | } | |
75 | ||
76 | atomic_inc(&realm->nref); | |
77 | } | |
78 | ||
a105f00c SW |
79 | static void __insert_snap_realm(struct rb_root *root, |
80 | struct ceph_snap_realm *new) | |
81 | { | |
82 | struct rb_node **p = &root->rb_node; | |
83 | struct rb_node *parent = NULL; | |
84 | struct ceph_snap_realm *r = NULL; | |
85 | ||
86 | while (*p) { | |
87 | parent = *p; | |
88 | r = rb_entry(parent, struct ceph_snap_realm, node); | |
89 | if (new->ino < r->ino) | |
90 | p = &(*p)->rb_left; | |
91 | else if (new->ino > r->ino) | |
92 | p = &(*p)->rb_right; | |
93 | else | |
94 | BUG(); | |
95 | } | |
96 | ||
97 | rb_link_node(&new->node, parent, p); | |
98 | rb_insert_color(&new->node, root); | |
99 | } | |
100 | ||
963b61eb SW |
101 | /* |
102 | * create and get the realm rooted at @ino and bump its ref count. | |
103 | * | |
104 | * caller must hold snap_rwsem for write. | |
105 | */ | |
106 | static struct ceph_snap_realm *ceph_create_snap_realm( | |
107 | struct ceph_mds_client *mdsc, | |
108 | u64 ino) | |
109 | { | |
110 | struct ceph_snap_realm *realm; | |
111 | ||
112 | realm = kzalloc(sizeof(*realm), GFP_NOFS); | |
113 | if (!realm) | |
114 | return ERR_PTR(-ENOMEM); | |
115 | ||
963b61eb SW |
116 | atomic_set(&realm->nref, 0); /* tree does not take a ref */ |
117 | realm->ino = ino; | |
118 | INIT_LIST_HEAD(&realm->children); | |
119 | INIT_LIST_HEAD(&realm->child_item); | |
120 | INIT_LIST_HEAD(&realm->empty_item); | |
121 | INIT_LIST_HEAD(&realm->inodes_with_caps); | |
122 | spin_lock_init(&realm->inodes_with_caps_lock); | |
a105f00c | 123 | __insert_snap_realm(&mdsc->snap_realms, realm); |
963b61eb SW |
124 | dout("create_snap_realm %llx %p\n", realm->ino, realm); |
125 | return realm; | |
126 | } | |
127 | ||
128 | /* | |
a105f00c | 129 | * lookup the realm rooted at @ino. |
963b61eb SW |
130 | * |
131 | * caller must hold snap_rwsem for write. | |
132 | */ | |
133 | struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc, | |
134 | u64 ino) | |
135 | { | |
a105f00c SW |
136 | struct rb_node *n = mdsc->snap_realms.rb_node; |
137 | struct ceph_snap_realm *r; | |
138 | ||
139 | while (n) { | |
140 | r = rb_entry(n, struct ceph_snap_realm, node); | |
141 | if (ino < r->ino) | |
142 | n = n->rb_left; | |
143 | else if (ino > r->ino) | |
144 | n = n->rb_right; | |
145 | else { | |
146 | dout("lookup_snap_realm %llx %p\n", r->ino, r); | |
147 | return r; | |
148 | } | |
149 | } | |
150 | return NULL; | |
963b61eb SW |
151 | } |
152 | ||
153 | static void __put_snap_realm(struct ceph_mds_client *mdsc, | |
154 | struct ceph_snap_realm *realm); | |
155 | ||
156 | /* | |
157 | * called with snap_rwsem (write) | |
158 | */ | |
159 | static void __destroy_snap_realm(struct ceph_mds_client *mdsc, | |
160 | struct ceph_snap_realm *realm) | |
161 | { | |
162 | dout("__destroy_snap_realm %p %llx\n", realm, realm->ino); | |
163 | ||
a105f00c | 164 | rb_erase(&realm->node, &mdsc->snap_realms); |
963b61eb SW |
165 | |
166 | if (realm->parent) { | |
167 | list_del_init(&realm->child_item); | |
168 | __put_snap_realm(mdsc, realm->parent); | |
169 | } | |
170 | ||
171 | kfree(realm->prior_parent_snaps); | |
172 | kfree(realm->snaps); | |
173 | ceph_put_snap_context(realm->cached_context); | |
174 | kfree(realm); | |
175 | } | |
176 | ||
177 | /* | |
178 | * caller holds snap_rwsem (write) | |
179 | */ | |
180 | static void __put_snap_realm(struct ceph_mds_client *mdsc, | |
181 | struct ceph_snap_realm *realm) | |
182 | { | |
183 | dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, | |
184 | atomic_read(&realm->nref), atomic_read(&realm->nref)-1); | |
185 | if (atomic_dec_and_test(&realm->nref)) | |
186 | __destroy_snap_realm(mdsc, realm); | |
187 | } | |
188 | ||
189 | /* | |
190 | * caller needn't hold any locks | |
191 | */ | |
192 | void ceph_put_snap_realm(struct ceph_mds_client *mdsc, | |
193 | struct ceph_snap_realm *realm) | |
194 | { | |
195 | dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, | |
196 | atomic_read(&realm->nref), atomic_read(&realm->nref)-1); | |
197 | if (!atomic_dec_and_test(&realm->nref)) | |
198 | return; | |
199 | ||
200 | if (down_write_trylock(&mdsc->snap_rwsem)) { | |
201 | __destroy_snap_realm(mdsc, realm); | |
202 | up_write(&mdsc->snap_rwsem); | |
203 | } else { | |
204 | spin_lock(&mdsc->snap_empty_lock); | |
205 | list_add(&mdsc->snap_empty, &realm->empty_item); | |
206 | spin_unlock(&mdsc->snap_empty_lock); | |
207 | } | |
208 | } | |
209 | ||
210 | /* | |
211 | * Clean up any realms whose ref counts have dropped to zero. Note | |
212 | * that this does not include realms who were created but not yet | |
213 | * used. | |
214 | * | |
215 | * Called under snap_rwsem (write) | |
216 | */ | |
217 | static void __cleanup_empty_realms(struct ceph_mds_client *mdsc) | |
218 | { | |
219 | struct ceph_snap_realm *realm; | |
220 | ||
221 | spin_lock(&mdsc->snap_empty_lock); | |
222 | while (!list_empty(&mdsc->snap_empty)) { | |
223 | realm = list_first_entry(&mdsc->snap_empty, | |
224 | struct ceph_snap_realm, empty_item); | |
225 | list_del(&realm->empty_item); | |
226 | spin_unlock(&mdsc->snap_empty_lock); | |
227 | __destroy_snap_realm(mdsc, realm); | |
228 | spin_lock(&mdsc->snap_empty_lock); | |
229 | } | |
230 | spin_unlock(&mdsc->snap_empty_lock); | |
231 | } | |
232 | ||
233 | void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc) | |
234 | { | |
235 | down_write(&mdsc->snap_rwsem); | |
236 | __cleanup_empty_realms(mdsc); | |
237 | up_write(&mdsc->snap_rwsem); | |
238 | } | |
239 | ||
240 | /* | |
241 | * adjust the parent realm of a given @realm. adjust child list, and parent | |
242 | * pointers, and ref counts appropriately. | |
243 | * | |
244 | * return true if parent was changed, 0 if unchanged, <0 on error. | |
245 | * | |
246 | * caller must hold snap_rwsem for write. | |
247 | */ | |
248 | static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc, | |
249 | struct ceph_snap_realm *realm, | |
250 | u64 parentino) | |
251 | { | |
252 | struct ceph_snap_realm *parent; | |
253 | ||
254 | if (realm->parent_ino == parentino) | |
255 | return 0; | |
256 | ||
257 | parent = ceph_lookup_snap_realm(mdsc, parentino); | |
963b61eb SW |
258 | if (!parent) { |
259 | parent = ceph_create_snap_realm(mdsc, parentino); | |
260 | if (IS_ERR(parent)) | |
261 | return PTR_ERR(parent); | |
262 | } | |
263 | dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n", | |
264 | realm->ino, realm, realm->parent_ino, realm->parent, | |
265 | parentino, parent); | |
266 | if (realm->parent) { | |
267 | list_del_init(&realm->child_item); | |
268 | ceph_put_snap_realm(mdsc, realm->parent); | |
269 | } | |
270 | realm->parent_ino = parentino; | |
271 | realm->parent = parent; | |
272 | ceph_get_snap_realm(mdsc, parent); | |
273 | list_add(&realm->child_item, &parent->children); | |
274 | return 1; | |
275 | } | |
276 | ||
277 | ||
278 | static int cmpu64_rev(const void *a, const void *b) | |
279 | { | |
280 | if (*(u64 *)a < *(u64 *)b) | |
281 | return 1; | |
282 | if (*(u64 *)a > *(u64 *)b) | |
283 | return -1; | |
284 | return 0; | |
285 | } | |
286 | ||
287 | /* | |
288 | * build the snap context for a given realm. | |
289 | */ | |
290 | static int build_snap_context(struct ceph_snap_realm *realm) | |
291 | { | |
292 | struct ceph_snap_realm *parent = realm->parent; | |
293 | struct ceph_snap_context *snapc; | |
294 | int err = 0; | |
295 | int i; | |
296 | int num = realm->num_prior_parent_snaps + realm->num_snaps; | |
297 | ||
298 | /* | |
299 | * build parent context, if it hasn't been built. | |
300 | * conservatively estimate that all parent snaps might be | |
301 | * included by us. | |
302 | */ | |
303 | if (parent) { | |
304 | if (!parent->cached_context) { | |
305 | err = build_snap_context(parent); | |
306 | if (err) | |
307 | goto fail; | |
308 | } | |
309 | num += parent->cached_context->num_snaps; | |
310 | } | |
311 | ||
312 | /* do i actually need to update? not if my context seq | |
313 | matches realm seq, and my parents' does to. (this works | |
314 | because we rebuild_snap_realms() works _downward_ in | |
315 | hierarchy after each update.) */ | |
316 | if (realm->cached_context && | |
317 | realm->cached_context->seq <= realm->seq && | |
318 | (!parent || | |
319 | realm->cached_context->seq <= parent->cached_context->seq)) { | |
320 | dout("build_snap_context %llx %p: %p seq %lld (%d snaps)" | |
321 | " (unchanged)\n", | |
322 | realm->ino, realm, realm->cached_context, | |
323 | realm->cached_context->seq, | |
324 | realm->cached_context->num_snaps); | |
325 | return 0; | |
326 | } | |
327 | ||
328 | /* alloc new snap context */ | |
329 | err = -ENOMEM; | |
330 | if (num > ULONG_MAX / sizeof(u64) - sizeof(*snapc)) | |
331 | goto fail; | |
332 | snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS); | |
333 | if (!snapc) | |
334 | goto fail; | |
335 | atomic_set(&snapc->nref, 1); | |
336 | ||
337 | /* build (reverse sorted) snap vector */ | |
338 | num = 0; | |
339 | snapc->seq = realm->seq; | |
340 | if (parent) { | |
341 | /* include any of parent's snaps occuring _after_ my | |
342 | parent became my parent */ | |
343 | for (i = 0; i < parent->cached_context->num_snaps; i++) | |
344 | if (parent->cached_context->snaps[i] >= | |
345 | realm->parent_since) | |
346 | snapc->snaps[num++] = | |
347 | parent->cached_context->snaps[i]; | |
348 | if (parent->cached_context->seq > snapc->seq) | |
349 | snapc->seq = parent->cached_context->seq; | |
350 | } | |
351 | memcpy(snapc->snaps + num, realm->snaps, | |
352 | sizeof(u64)*realm->num_snaps); | |
353 | num += realm->num_snaps; | |
354 | memcpy(snapc->snaps + num, realm->prior_parent_snaps, | |
355 | sizeof(u64)*realm->num_prior_parent_snaps); | |
356 | num += realm->num_prior_parent_snaps; | |
357 | ||
358 | sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL); | |
359 | snapc->num_snaps = num; | |
360 | dout("build_snap_context %llx %p: %p seq %lld (%d snaps)\n", | |
361 | realm->ino, realm, snapc, snapc->seq, snapc->num_snaps); | |
362 | ||
363 | if (realm->cached_context) | |
364 | ceph_put_snap_context(realm->cached_context); | |
365 | realm->cached_context = snapc; | |
366 | return 0; | |
367 | ||
368 | fail: | |
369 | /* | |
370 | * if we fail, clear old (incorrect) cached_context... hopefully | |
371 | * we'll have better luck building it later | |
372 | */ | |
373 | if (realm->cached_context) { | |
374 | ceph_put_snap_context(realm->cached_context); | |
375 | realm->cached_context = NULL; | |
376 | } | |
377 | pr_err("build_snap_context %llx %p fail %d\n", realm->ino, | |
378 | realm, err); | |
379 | return err; | |
380 | } | |
381 | ||
382 | /* | |
383 | * rebuild snap context for the given realm and all of its children. | |
384 | */ | |
385 | static void rebuild_snap_realms(struct ceph_snap_realm *realm) | |
386 | { | |
387 | struct ceph_snap_realm *child; | |
388 | ||
389 | dout("rebuild_snap_realms %llx %p\n", realm->ino, realm); | |
390 | build_snap_context(realm); | |
391 | ||
392 | list_for_each_entry(child, &realm->children, child_item) | |
393 | rebuild_snap_realms(child); | |
394 | } | |
395 | ||
396 | ||
397 | /* | |
398 | * helper to allocate and decode an array of snapids. free prior | |
399 | * instance, if any. | |
400 | */ | |
401 | static int dup_array(u64 **dst, __le64 *src, int num) | |
402 | { | |
403 | int i; | |
404 | ||
405 | kfree(*dst); | |
406 | if (num) { | |
407 | *dst = kcalloc(num, sizeof(u64), GFP_NOFS); | |
408 | if (!*dst) | |
409 | return -ENOMEM; | |
410 | for (i = 0; i < num; i++) | |
411 | (*dst)[i] = get_unaligned_le64(src + i); | |
412 | } else { | |
413 | *dst = NULL; | |
414 | } | |
415 | return 0; | |
416 | } | |
417 | ||
418 | ||
419 | /* | |
420 | * When a snapshot is applied, the size/mtime inode metadata is queued | |
421 | * in a ceph_cap_snap (one for each snapshot) until writeback | |
422 | * completes and the metadata can be flushed back to the MDS. | |
423 | * | |
424 | * However, if a (sync) write is currently in-progress when we apply | |
425 | * the snapshot, we have to wait until the write succeeds or fails | |
426 | * (and a final size/mtime is known). In this case the | |
427 | * cap_snap->writing = 1, and is said to be "pending." When the write | |
428 | * finishes, we __ceph_finish_cap_snap(). | |
429 | * | |
430 | * Caller must hold snap_rwsem for read (i.e., the realm topology won't | |
431 | * change). | |
432 | */ | |
433 | void ceph_queue_cap_snap(struct ceph_inode_info *ci, | |
434 | struct ceph_snap_context *snapc) | |
435 | { | |
436 | struct inode *inode = &ci->vfs_inode; | |
437 | struct ceph_cap_snap *capsnap; | |
438 | int used; | |
439 | ||
440 | capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS); | |
441 | if (!capsnap) { | |
442 | pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode); | |
443 | return; | |
444 | } | |
445 | ||
446 | spin_lock(&inode->i_lock); | |
447 | used = __ceph_caps_used(ci); | |
448 | if (__ceph_have_pending_cap_snap(ci)) { | |
449 | /* there is no point in queuing multiple "pending" cap_snaps, | |
450 | as no new writes are allowed to start when pending, so any | |
451 | writes in progress now were started before the previous | |
452 | cap_snap. lucky us. */ | |
453 | dout("queue_cap_snap %p snapc %p seq %llu used %d" | |
454 | " already pending\n", inode, snapc, snapc->seq, used); | |
455 | kfree(capsnap); | |
456 | } else if (ci->i_wrbuffer_ref_head || (used & CEPH_CAP_FILE_WR)) { | |
457 | igrab(inode); | |
458 | ||
459 | atomic_set(&capsnap->nref, 1); | |
460 | capsnap->ci = ci; | |
461 | INIT_LIST_HEAD(&capsnap->ci_item); | |
462 | INIT_LIST_HEAD(&capsnap->flushing_item); | |
463 | ||
464 | capsnap->follows = snapc->seq - 1; | |
465 | capsnap->context = ceph_get_snap_context(snapc); | |
466 | capsnap->issued = __ceph_caps_issued(ci, NULL); | |
467 | capsnap->dirty = __ceph_caps_dirty(ci); | |
468 | ||
469 | capsnap->mode = inode->i_mode; | |
470 | capsnap->uid = inode->i_uid; | |
471 | capsnap->gid = inode->i_gid; | |
472 | ||
473 | /* fixme? */ | |
474 | capsnap->xattr_blob = NULL; | |
475 | capsnap->xattr_len = 0; | |
476 | ||
477 | /* dirty page count moved from _head to this cap_snap; | |
478 | all subsequent writes page dirties occur _after_ this | |
479 | snapshot. */ | |
480 | capsnap->dirty_pages = ci->i_wrbuffer_ref_head; | |
481 | ci->i_wrbuffer_ref_head = 0; | |
482 | ceph_put_snap_context(ci->i_head_snapc); | |
483 | ci->i_head_snapc = NULL; | |
484 | list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps); | |
485 | ||
486 | if (used & CEPH_CAP_FILE_WR) { | |
487 | dout("queue_cap_snap %p cap_snap %p snapc %p" | |
488 | " seq %llu used WR, now pending\n", inode, | |
489 | capsnap, snapc, snapc->seq); | |
490 | capsnap->writing = 1; | |
491 | } else { | |
492 | /* note mtime, size NOW. */ | |
493 | __ceph_finish_cap_snap(ci, capsnap); | |
494 | } | |
495 | } else { | |
496 | dout("queue_cap_snap %p nothing dirty|writing\n", inode); | |
497 | kfree(capsnap); | |
498 | } | |
499 | ||
500 | spin_unlock(&inode->i_lock); | |
501 | } | |
502 | ||
503 | /* | |
504 | * Finalize the size, mtime for a cap_snap.. that is, settle on final values | |
505 | * to be used for the snapshot, to be flushed back to the mds. | |
506 | * | |
507 | * If capsnap can now be flushed, add to snap_flush list, and return 1. | |
508 | * | |
509 | * Caller must hold i_lock. | |
510 | */ | |
511 | int __ceph_finish_cap_snap(struct ceph_inode_info *ci, | |
512 | struct ceph_cap_snap *capsnap) | |
513 | { | |
514 | struct inode *inode = &ci->vfs_inode; | |
515 | struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc; | |
516 | ||
517 | BUG_ON(capsnap->writing); | |
518 | capsnap->size = inode->i_size; | |
519 | capsnap->mtime = inode->i_mtime; | |
520 | capsnap->atime = inode->i_atime; | |
521 | capsnap->ctime = inode->i_ctime; | |
522 | capsnap->time_warp_seq = ci->i_time_warp_seq; | |
523 | if (capsnap->dirty_pages) { | |
524 | dout("finish_cap_snap %p cap_snap %p snapc %p %llu s=%llu " | |
525 | "still has %d dirty pages\n", inode, capsnap, | |
526 | capsnap->context, capsnap->context->seq, | |
527 | capsnap->size, capsnap->dirty_pages); | |
528 | return 0; | |
529 | } | |
530 | dout("finish_cap_snap %p cap_snap %p snapc %p %llu s=%llu clean\n", | |
531 | inode, capsnap, capsnap->context, | |
532 | capsnap->context->seq, capsnap->size); | |
533 | ||
534 | spin_lock(&mdsc->snap_flush_lock); | |
535 | list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list); | |
536 | spin_unlock(&mdsc->snap_flush_lock); | |
537 | return 1; /* caller may want to ceph_flush_snaps */ | |
538 | } | |
539 | ||
540 | ||
541 | /* | |
542 | * Parse and apply a snapblob "snap trace" from the MDS. This specifies | |
543 | * the snap realm parameters from a given realm and all of its ancestors, | |
544 | * up to the root. | |
545 | * | |
546 | * Caller must hold snap_rwsem for write. | |
547 | */ | |
548 | int ceph_update_snap_trace(struct ceph_mds_client *mdsc, | |
549 | void *p, void *e, bool deletion) | |
550 | { | |
551 | struct ceph_mds_snap_realm *ri; /* encoded */ | |
552 | __le64 *snaps; /* encoded */ | |
553 | __le64 *prior_parent_snaps; /* encoded */ | |
554 | struct ceph_snap_realm *realm; | |
555 | int invalidate = 0; | |
556 | int err = -ENOMEM; | |
557 | ||
558 | dout("update_snap_trace deletion=%d\n", deletion); | |
559 | more: | |
560 | ceph_decode_need(&p, e, sizeof(*ri), bad); | |
561 | ri = p; | |
562 | p += sizeof(*ri); | |
563 | ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) + | |
564 | le32_to_cpu(ri->num_prior_parent_snaps)), bad); | |
565 | snaps = p; | |
566 | p += sizeof(u64) * le32_to_cpu(ri->num_snaps); | |
567 | prior_parent_snaps = p; | |
568 | p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps); | |
569 | ||
570 | realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino)); | |
963b61eb SW |
571 | if (!realm) { |
572 | realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino)); | |
573 | if (IS_ERR(realm)) { | |
574 | err = PTR_ERR(realm); | |
575 | goto fail; | |
576 | } | |
577 | } | |
578 | ||
579 | if (le64_to_cpu(ri->seq) > realm->seq) { | |
580 | dout("update_snap_trace updating %llx %p %lld -> %lld\n", | |
581 | realm->ino, realm, realm->seq, le64_to_cpu(ri->seq)); | |
582 | /* | |
583 | * if the realm seq has changed, queue a cap_snap for every | |
584 | * inode with open caps. we do this _before_ we update | |
585 | * the realm info so that we prepare for writeback under the | |
586 | * _previous_ snap context. | |
587 | * | |
588 | * ...unless it's a snap deletion! | |
589 | */ | |
590 | if (!deletion) { | |
591 | struct ceph_inode_info *ci; | |
592 | struct inode *lastinode = NULL; | |
593 | ||
594 | spin_lock(&realm->inodes_with_caps_lock); | |
595 | list_for_each_entry(ci, &realm->inodes_with_caps, | |
596 | i_snap_realm_item) { | |
597 | struct inode *inode = igrab(&ci->vfs_inode); | |
598 | if (!inode) | |
599 | continue; | |
600 | spin_unlock(&realm->inodes_with_caps_lock); | |
601 | if (lastinode) | |
602 | iput(lastinode); | |
603 | lastinode = inode; | |
604 | ceph_queue_cap_snap(ci, realm->cached_context); | |
605 | spin_lock(&realm->inodes_with_caps_lock); | |
606 | } | |
607 | spin_unlock(&realm->inodes_with_caps_lock); | |
608 | if (lastinode) | |
609 | iput(lastinode); | |
610 | dout("update_snap_trace cap_snaps queued\n"); | |
611 | } | |
612 | ||
613 | } else { | |
614 | dout("update_snap_trace %llx %p seq %lld unchanged\n", | |
615 | realm->ino, realm, realm->seq); | |
616 | } | |
617 | ||
618 | /* ensure the parent is correct */ | |
619 | err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent)); | |
620 | if (err < 0) | |
621 | goto fail; | |
622 | invalidate += err; | |
623 | ||
624 | if (le64_to_cpu(ri->seq) > realm->seq) { | |
625 | /* update realm parameters, snap lists */ | |
626 | realm->seq = le64_to_cpu(ri->seq); | |
627 | realm->created = le64_to_cpu(ri->created); | |
628 | realm->parent_since = le64_to_cpu(ri->parent_since); | |
629 | ||
630 | realm->num_snaps = le32_to_cpu(ri->num_snaps); | |
631 | err = dup_array(&realm->snaps, snaps, realm->num_snaps); | |
632 | if (err < 0) | |
633 | goto fail; | |
634 | ||
635 | realm->num_prior_parent_snaps = | |
636 | le32_to_cpu(ri->num_prior_parent_snaps); | |
637 | err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps, | |
638 | realm->num_prior_parent_snaps); | |
639 | if (err < 0) | |
640 | goto fail; | |
641 | ||
642 | invalidate = 1; | |
643 | } else if (!realm->cached_context) { | |
644 | invalidate = 1; | |
645 | } | |
646 | ||
647 | dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino, | |
648 | realm, invalidate, p, e); | |
649 | ||
650 | if (p < e) | |
651 | goto more; | |
652 | ||
653 | /* invalidate when we reach the _end_ (root) of the trace */ | |
654 | if (invalidate) | |
655 | rebuild_snap_realms(realm); | |
656 | ||
657 | __cleanup_empty_realms(mdsc); | |
658 | return 0; | |
659 | ||
660 | bad: | |
661 | err = -EINVAL; | |
662 | fail: | |
663 | pr_err("update_snap_trace error %d\n", err); | |
664 | return err; | |
665 | } | |
666 | ||
667 | ||
668 | /* | |
669 | * Send any cap_snaps that are queued for flush. Try to carry | |
670 | * s_mutex across multiple snap flushes to avoid locking overhead. | |
671 | * | |
672 | * Caller holds no locks. | |
673 | */ | |
674 | static void flush_snaps(struct ceph_mds_client *mdsc) | |
675 | { | |
676 | struct ceph_inode_info *ci; | |
677 | struct inode *inode; | |
678 | struct ceph_mds_session *session = NULL; | |
679 | ||
680 | dout("flush_snaps\n"); | |
681 | spin_lock(&mdsc->snap_flush_lock); | |
682 | while (!list_empty(&mdsc->snap_flush_list)) { | |
683 | ci = list_first_entry(&mdsc->snap_flush_list, | |
684 | struct ceph_inode_info, i_snap_flush_item); | |
685 | inode = &ci->vfs_inode; | |
686 | igrab(inode); | |
687 | spin_unlock(&mdsc->snap_flush_lock); | |
688 | spin_lock(&inode->i_lock); | |
689 | __ceph_flush_snaps(ci, &session); | |
690 | spin_unlock(&inode->i_lock); | |
691 | iput(inode); | |
692 | spin_lock(&mdsc->snap_flush_lock); | |
693 | } | |
694 | spin_unlock(&mdsc->snap_flush_lock); | |
695 | ||
696 | if (session) { | |
697 | mutex_unlock(&session->s_mutex); | |
698 | ceph_put_mds_session(session); | |
699 | } | |
700 | dout("flush_snaps done\n"); | |
701 | } | |
702 | ||
703 | ||
704 | /* | |
705 | * Handle a snap notification from the MDS. | |
706 | * | |
707 | * This can take two basic forms: the simplest is just a snap creation | |
708 | * or deletion notification on an existing realm. This should update the | |
709 | * realm and its children. | |
710 | * | |
711 | * The more difficult case is realm creation, due to snap creation at a | |
712 | * new point in the file hierarchy, or due to a rename that moves a file or | |
713 | * directory into another realm. | |
714 | */ | |
715 | void ceph_handle_snap(struct ceph_mds_client *mdsc, | |
2600d2dd | 716 | struct ceph_mds_session *session, |
963b61eb SW |
717 | struct ceph_msg *msg) |
718 | { | |
719 | struct super_block *sb = mdsc->client->sb; | |
2600d2dd | 720 | int mds = session->s_mds; |
963b61eb SW |
721 | u64 split; |
722 | int op; | |
723 | int trace_len; | |
724 | struct ceph_snap_realm *realm = NULL; | |
725 | void *p = msg->front.iov_base; | |
726 | void *e = p + msg->front.iov_len; | |
727 | struct ceph_mds_snap_head *h; | |
728 | int num_split_inos, num_split_realms; | |
729 | __le64 *split_inos = NULL, *split_realms = NULL; | |
730 | int i; | |
731 | int locked_rwsem = 0; | |
732 | ||
963b61eb SW |
733 | /* decode */ |
734 | if (msg->front.iov_len < sizeof(*h)) | |
735 | goto bad; | |
736 | h = p; | |
737 | op = le32_to_cpu(h->op); | |
738 | split = le64_to_cpu(h->split); /* non-zero if we are splitting an | |
739 | * existing realm */ | |
740 | num_split_inos = le32_to_cpu(h->num_split_inos); | |
741 | num_split_realms = le32_to_cpu(h->num_split_realms); | |
742 | trace_len = le32_to_cpu(h->trace_len); | |
743 | p += sizeof(*h); | |
744 | ||
745 | dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds, | |
746 | ceph_snap_op_name(op), split, trace_len); | |
747 | ||
963b61eb SW |
748 | mutex_lock(&session->s_mutex); |
749 | session->s_seq++; | |
750 | mutex_unlock(&session->s_mutex); | |
751 | ||
752 | down_write(&mdsc->snap_rwsem); | |
753 | locked_rwsem = 1; | |
754 | ||
755 | if (op == CEPH_SNAP_OP_SPLIT) { | |
756 | struct ceph_mds_snap_realm *ri; | |
757 | ||
758 | /* | |
759 | * A "split" breaks part of an existing realm off into | |
760 | * a new realm. The MDS provides a list of inodes | |
761 | * (with caps) and child realms that belong to the new | |
762 | * child. | |
763 | */ | |
764 | split_inos = p; | |
765 | p += sizeof(u64) * num_split_inos; | |
766 | split_realms = p; | |
767 | p += sizeof(u64) * num_split_realms; | |
768 | ceph_decode_need(&p, e, sizeof(*ri), bad); | |
769 | /* we will peek at realm info here, but will _not_ | |
770 | * advance p, as the realm update will occur below in | |
771 | * ceph_update_snap_trace. */ | |
772 | ri = p; | |
773 | ||
774 | realm = ceph_lookup_snap_realm(mdsc, split); | |
963b61eb SW |
775 | if (!realm) { |
776 | realm = ceph_create_snap_realm(mdsc, split); | |
777 | if (IS_ERR(realm)) | |
778 | goto out; | |
779 | } | |
780 | ceph_get_snap_realm(mdsc, realm); | |
781 | ||
782 | dout("splitting snap_realm %llx %p\n", realm->ino, realm); | |
783 | for (i = 0; i < num_split_inos; i++) { | |
784 | struct ceph_vino vino = { | |
785 | .ino = le64_to_cpu(split_inos[i]), | |
786 | .snap = CEPH_NOSNAP, | |
787 | }; | |
788 | struct inode *inode = ceph_find_inode(sb, vino); | |
789 | struct ceph_inode_info *ci; | |
790 | ||
791 | if (!inode) | |
792 | continue; | |
793 | ci = ceph_inode(inode); | |
794 | ||
795 | spin_lock(&inode->i_lock); | |
796 | if (!ci->i_snap_realm) | |
797 | goto skip_inode; | |
798 | /* | |
799 | * If this inode belongs to a realm that was | |
800 | * created after our new realm, we experienced | |
801 | * a race (due to another split notifications | |
802 | * arriving from a different MDS). So skip | |
803 | * this inode. | |
804 | */ | |
805 | if (ci->i_snap_realm->created > | |
806 | le64_to_cpu(ri->created)) { | |
807 | dout(" leaving %p in newer realm %llx %p\n", | |
808 | inode, ci->i_snap_realm->ino, | |
809 | ci->i_snap_realm); | |
810 | goto skip_inode; | |
811 | } | |
812 | dout(" will move %p to split realm %llx %p\n", | |
813 | inode, realm->ino, realm); | |
814 | /* | |
815 | * Remove the inode from the realm's inode | |
816 | * list, but don't add it to the new realm | |
817 | * yet. We don't want the cap_snap to be | |
818 | * queued (again) by ceph_update_snap_trace() | |
819 | * below. Queue it _now_, under the old context. | |
820 | */ | |
821 | list_del_init(&ci->i_snap_realm_item); | |
822 | spin_unlock(&inode->i_lock); | |
823 | ||
824 | ceph_queue_cap_snap(ci, | |
825 | ci->i_snap_realm->cached_context); | |
826 | ||
827 | iput(inode); | |
828 | continue; | |
829 | ||
830 | skip_inode: | |
831 | spin_unlock(&inode->i_lock); | |
832 | iput(inode); | |
833 | } | |
834 | ||
835 | /* we may have taken some of the old realm's children. */ | |
836 | for (i = 0; i < num_split_realms; i++) { | |
837 | struct ceph_snap_realm *child = | |
838 | ceph_lookup_snap_realm(mdsc, | |
839 | le64_to_cpu(split_realms[i])); | |
963b61eb SW |
840 | if (!child) |
841 | continue; | |
842 | adjust_snap_realm_parent(mdsc, child, realm->ino); | |
843 | } | |
844 | } | |
845 | ||
846 | /* | |
847 | * update using the provided snap trace. if we are deleting a | |
848 | * snap, we can avoid queueing cap_snaps. | |
849 | */ | |
850 | ceph_update_snap_trace(mdsc, p, e, | |
851 | op == CEPH_SNAP_OP_DESTROY); | |
852 | ||
853 | if (op == CEPH_SNAP_OP_SPLIT) { | |
854 | /* | |
855 | * ok, _now_ add the inodes into the new realm. | |
856 | */ | |
857 | for (i = 0; i < num_split_inos; i++) { | |
858 | struct ceph_vino vino = { | |
859 | .ino = le64_to_cpu(split_inos[i]), | |
860 | .snap = CEPH_NOSNAP, | |
861 | }; | |
862 | struct inode *inode = ceph_find_inode(sb, vino); | |
863 | struct ceph_inode_info *ci; | |
864 | ||
865 | if (!inode) | |
866 | continue; | |
867 | ci = ceph_inode(inode); | |
868 | spin_lock(&inode->i_lock); | |
869 | if (!ci->i_snap_realm) | |
870 | goto split_skip_inode; | |
871 | ceph_put_snap_realm(mdsc, ci->i_snap_realm); | |
872 | spin_lock(&realm->inodes_with_caps_lock); | |
873 | list_add(&ci->i_snap_realm_item, | |
874 | &realm->inodes_with_caps); | |
875 | ci->i_snap_realm = realm; | |
876 | spin_unlock(&realm->inodes_with_caps_lock); | |
877 | ceph_get_snap_realm(mdsc, realm); | |
878 | split_skip_inode: | |
879 | spin_unlock(&inode->i_lock); | |
880 | iput(inode); | |
881 | } | |
882 | ||
883 | /* we took a reference when we created the realm, above */ | |
884 | ceph_put_snap_realm(mdsc, realm); | |
885 | } | |
886 | ||
887 | __cleanup_empty_realms(mdsc); | |
888 | ||
889 | up_write(&mdsc->snap_rwsem); | |
890 | ||
891 | flush_snaps(mdsc); | |
892 | return; | |
893 | ||
894 | bad: | |
895 | pr_err("corrupt snap message from mds%d\n", mds); | |
9ec7cab1 | 896 | ceph_msg_dump(msg); |
963b61eb SW |
897 | out: |
898 | if (locked_rwsem) | |
899 | up_write(&mdsc->snap_rwsem); | |
900 | return; | |
901 | } | |
902 | ||
903 | ||
904 |