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1#include <linux/ceph/ceph_debug.h>
2
3#include <linux/sort.h>
4#include <linux/slab.h>
5
6#include "super.h"
7#include "mds_client.h"
8
9#include <linux/ceph/decode.h>
10
11/*
12 * Snapshots in ceph are driven in large part by cooperation from the
13 * client. In contrast to local file systems or file servers that
14 * implement snapshots at a single point in the system, ceph's
15 * distributed access to storage requires clients to help decide
16 * whether a write logically occurs before or after a recently created
17 * snapshot.
18 *
19 * This provides a perfect instantanous client-wide snapshot. Between
20 * clients, however, snapshots may appear to be applied at slightly
21 * different points in time, depending on delays in delivering the
22 * snapshot notification.
23 *
24 * Snapshots are _not_ file system-wide. Instead, each snapshot
25 * applies to the subdirectory nested beneath some directory. This
26 * effectively divides the hierarchy into multiple "realms," where all
27 * of the files contained by each realm share the same set of
28 * snapshots. An individual realm's snap set contains snapshots
29 * explicitly created on that realm, as well as any snaps in its
30 * parent's snap set _after_ the point at which the parent became it's
31 * parent (due to, say, a rename). Similarly, snaps from prior parents
32 * during the time intervals during which they were the parent are included.
33 *
34 * The client is spared most of this detail, fortunately... it must only
35 * maintains a hierarchy of realms reflecting the current parent/child
36 * realm relationship, and for each realm has an explicit list of snaps
37 * inherited from prior parents.
38 *
39 * A snap_realm struct is maintained for realms containing every inode
40 * with an open cap in the system. (The needed snap realm information is
41 * provided by the MDS whenever a cap is issued, i.e., on open.) A 'seq'
42 * version number is used to ensure that as realm parameters change (new
43 * snapshot, new parent, etc.) the client's realm hierarchy is updated.
44 *
45 * The realm hierarchy drives the generation of a 'snap context' for each
46 * realm, which simply lists the resulting set of snaps for the realm. This
47 * is attached to any writes sent to OSDs.
48 */
49/*
50 * Unfortunately error handling is a bit mixed here. If we get a snap
51 * update, but don't have enough memory to update our realm hierarchy,
52 * it's not clear what we can do about it (besides complaining to the
53 * console).
54 */
55
56
57/*
58 * increase ref count for the realm
59 *
60 * caller must hold snap_rwsem for write.
61 */
62void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
63 struct ceph_snap_realm *realm)
64{
65 dout("get_realm %p %d -> %d\n", realm,
66 atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
67 /*
68 * since we _only_ increment realm refs or empty the empty
69 * list with snap_rwsem held, adjusting the empty list here is
70 * safe. we do need to protect against concurrent empty list
71 * additions, however.
72 */
73 if (atomic_inc_return(&realm->nref) == 1) {
74 spin_lock(&mdsc->snap_empty_lock);
75 list_del_init(&realm->empty_item);
76 spin_unlock(&mdsc->snap_empty_lock);
77 }
78}
79
80static void __insert_snap_realm(struct rb_root *root,
81 struct ceph_snap_realm *new)
82{
83 struct rb_node **p = &root->rb_node;
84 struct rb_node *parent = NULL;
85 struct ceph_snap_realm *r = NULL;
86
87 while (*p) {
88 parent = *p;
89 r = rb_entry(parent, struct ceph_snap_realm, node);
90 if (new->ino < r->ino)
91 p = &(*p)->rb_left;
92 else if (new->ino > r->ino)
93 p = &(*p)->rb_right;
94 else
95 BUG();
96 }
97
98 rb_link_node(&new->node, parent, p);
99 rb_insert_color(&new->node, root);
100}
101
102/*
103 * create and get the realm rooted at @ino and bump its ref count.
104 *
105 * caller must hold snap_rwsem for write.
106 */
107static struct ceph_snap_realm *ceph_create_snap_realm(
108 struct ceph_mds_client *mdsc,
109 u64 ino)
110{
111 struct ceph_snap_realm *realm;
112
113 realm = kzalloc(sizeof(*realm), GFP_NOFS);
114 if (!realm)
115 return ERR_PTR(-ENOMEM);
116
117 atomic_set(&realm->nref, 1); /* for caller */
118 realm->ino = ino;
119 INIT_LIST_HEAD(&realm->children);
120 INIT_LIST_HEAD(&realm->child_item);
121 INIT_LIST_HEAD(&realm->empty_item);
122 INIT_LIST_HEAD(&realm->dirty_item);
123 INIT_LIST_HEAD(&realm->inodes_with_caps);
124 spin_lock_init(&realm->inodes_with_caps_lock);
125 __insert_snap_realm(&mdsc->snap_realms, realm);
126 dout("create_snap_realm %llx %p\n", realm->ino, realm);
127 return realm;
128}
129
130/*
131 * lookup the realm rooted at @ino.
132 *
133 * caller must hold snap_rwsem for write.
134 */
135static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
136 u64 ino)
137{
138 struct rb_node *n = mdsc->snap_realms.rb_node;
139 struct ceph_snap_realm *r;
140
141 while (n) {
142 r = rb_entry(n, struct ceph_snap_realm, node);
143 if (ino < r->ino)
144 n = n->rb_left;
145 else if (ino > r->ino)
146 n = n->rb_right;
147 else {
148 dout("lookup_snap_realm %llx %p\n", r->ino, r);
149 return r;
150 }
151 }
152 return NULL;
153}
154
155struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
156 u64 ino)
157{
158 struct ceph_snap_realm *r;
159 r = __lookup_snap_realm(mdsc, ino);
160 if (r)
161 ceph_get_snap_realm(mdsc, r);
162 return r;
163}
164
165static void __put_snap_realm(struct ceph_mds_client *mdsc,
166 struct ceph_snap_realm *realm);
167
168/*
169 * called with snap_rwsem (write)
170 */
171static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
172 struct ceph_snap_realm *realm)
173{
174 dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
175
176 rb_erase(&realm->node, &mdsc->snap_realms);
177
178 if (realm->parent) {
179 list_del_init(&realm->child_item);
180 __put_snap_realm(mdsc, realm->parent);
181 }
182
183 kfree(realm->prior_parent_snaps);
184 kfree(realm->snaps);
185 ceph_put_snap_context(realm->cached_context);
186 kfree(realm);
187}
188
189/*
190 * caller holds snap_rwsem (write)
191 */
192static void __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 __destroy_snap_realm(mdsc, realm);
199}
200
201/*
202 * caller needn't hold any locks
203 */
204void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
205 struct ceph_snap_realm *realm)
206{
207 dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
208 atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
209 if (!atomic_dec_and_test(&realm->nref))
210 return;
211
212 if (down_write_trylock(&mdsc->snap_rwsem)) {
213 __destroy_snap_realm(mdsc, realm);
214 up_write(&mdsc->snap_rwsem);
215 } else {
216 spin_lock(&mdsc->snap_empty_lock);
217 list_add(&realm->empty_item, &mdsc->snap_empty);
218 spin_unlock(&mdsc->snap_empty_lock);
219 }
220}
221
222/*
223 * Clean up any realms whose ref counts have dropped to zero. Note
224 * that this does not include realms who were created but not yet
225 * used.
226 *
227 * Called under snap_rwsem (write)
228 */
229static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
230{
231 struct ceph_snap_realm *realm;
232
233 spin_lock(&mdsc->snap_empty_lock);
234 while (!list_empty(&mdsc->snap_empty)) {
235 realm = list_first_entry(&mdsc->snap_empty,
236 struct ceph_snap_realm, empty_item);
237 list_del(&realm->empty_item);
238 spin_unlock(&mdsc->snap_empty_lock);
239 __destroy_snap_realm(mdsc, realm);
240 spin_lock(&mdsc->snap_empty_lock);
241 }
242 spin_unlock(&mdsc->snap_empty_lock);
243}
244
245void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc)
246{
247 down_write(&mdsc->snap_rwsem);
248 __cleanup_empty_realms(mdsc);
249 up_write(&mdsc->snap_rwsem);
250}
251
252/*
253 * adjust the parent realm of a given @realm. adjust child list, and parent
254 * pointers, and ref counts appropriately.
255 *
256 * return true if parent was changed, 0 if unchanged, <0 on error.
257 *
258 * caller must hold snap_rwsem for write.
259 */
260static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
261 struct ceph_snap_realm *realm,
262 u64 parentino)
263{
264 struct ceph_snap_realm *parent;
265
266 if (realm->parent_ino == parentino)
267 return 0;
268
269 parent = ceph_lookup_snap_realm(mdsc, parentino);
270 if (!parent) {
271 parent = ceph_create_snap_realm(mdsc, parentino);
272 if (IS_ERR(parent))
273 return PTR_ERR(parent);
274 }
275 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
276 realm->ino, realm, realm->parent_ino, realm->parent,
277 parentino, parent);
278 if (realm->parent) {
279 list_del_init(&realm->child_item);
280 ceph_put_snap_realm(mdsc, realm->parent);
281 }
282 realm->parent_ino = parentino;
283 realm->parent = parent;
284 list_add(&realm->child_item, &parent->children);
285 return 1;
286}
287
288
289static int cmpu64_rev(const void *a, const void *b)
290{
291 if (*(u64 *)a < *(u64 *)b)
292 return 1;
293 if (*(u64 *)a > *(u64 *)b)
294 return -1;
295 return 0;
296}
297
298
299/*
300 * build the snap context for a given realm.
301 */
302static int build_snap_context(struct ceph_snap_realm *realm)
303{
304 struct ceph_snap_realm *parent = realm->parent;
305 struct ceph_snap_context *snapc;
306 int err = 0;
307 u32 num = realm->num_prior_parent_snaps + realm->num_snaps;
308
309 /*
310 * build parent context, if it hasn't been built.
311 * conservatively estimate that all parent snaps might be
312 * included by us.
313 */
314 if (parent) {
315 if (!parent->cached_context) {
316 err = build_snap_context(parent);
317 if (err)
318 goto fail;
319 }
320 num += parent->cached_context->num_snaps;
321 }
322
323 /* do i actually need to update? not if my context seq
324 matches realm seq, and my parents' does to. (this works
325 because we rebuild_snap_realms() works _downward_ in
326 hierarchy after each update.) */
327 if (realm->cached_context &&
328 realm->cached_context->seq == realm->seq &&
329 (!parent ||
330 realm->cached_context->seq >= parent->cached_context->seq)) {
331 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)"
332 " (unchanged)\n",
333 realm->ino, realm, realm->cached_context,
334 realm->cached_context->seq,
335 (unsigned int) realm->cached_context->num_snaps);
336 return 0;
337 }
338
339 /* alloc new snap context */
340 err = -ENOMEM;
341 if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
342 goto fail;
343 snapc = ceph_create_snap_context(num, GFP_NOFS);
344 if (!snapc)
345 goto fail;
346
347 /* build (reverse sorted) snap vector */
348 num = 0;
349 snapc->seq = realm->seq;
350 if (parent) {
351 u32 i;
352
353 /* include any of parent's snaps occurring _after_ my
354 parent became my parent */
355 for (i = 0; i < parent->cached_context->num_snaps; i++)
356 if (parent->cached_context->snaps[i] >=
357 realm->parent_since)
358 snapc->snaps[num++] =
359 parent->cached_context->snaps[i];
360 if (parent->cached_context->seq > snapc->seq)
361 snapc->seq = parent->cached_context->seq;
362 }
363 memcpy(snapc->snaps + num, realm->snaps,
364 sizeof(u64)*realm->num_snaps);
365 num += realm->num_snaps;
366 memcpy(snapc->snaps + num, realm->prior_parent_snaps,
367 sizeof(u64)*realm->num_prior_parent_snaps);
368 num += realm->num_prior_parent_snaps;
369
370 sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL);
371 snapc->num_snaps = num;
372 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)\n",
373 realm->ino, realm, snapc, snapc->seq,
374 (unsigned int) snapc->num_snaps);
375
376 ceph_put_snap_context(realm->cached_context);
377 realm->cached_context = snapc;
378 return 0;
379
380fail:
381 /*
382 * if we fail, clear old (incorrect) cached_context... hopefully
383 * we'll have better luck building it later
384 */
385 if (realm->cached_context) {
386 ceph_put_snap_context(realm->cached_context);
387 realm->cached_context = NULL;
388 }
389 pr_err("build_snap_context %llx %p fail %d\n", realm->ino,
390 realm, err);
391 return err;
392}
393
394/*
395 * rebuild snap context for the given realm and all of its children.
396 */
397static void rebuild_snap_realms(struct ceph_snap_realm *realm)
398{
399 struct ceph_snap_realm *child;
400
401 dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
402 build_snap_context(realm);
403
404 list_for_each_entry(child, &realm->children, child_item)
405 rebuild_snap_realms(child);
406}
407
408
409/*
410 * helper to allocate and decode an array of snapids. free prior
411 * instance, if any.
412 */
413static int dup_array(u64 **dst, __le64 *src, u32 num)
414{
415 u32 i;
416
417 kfree(*dst);
418 if (num) {
419 *dst = kcalloc(num, sizeof(u64), GFP_NOFS);
420 if (!*dst)
421 return -ENOMEM;
422 for (i = 0; i < num; i++)
423 (*dst)[i] = get_unaligned_le64(src + i);
424 } else {
425 *dst = NULL;
426 }
427 return 0;
428}
429
430static bool has_new_snaps(struct ceph_snap_context *o,
431 struct ceph_snap_context *n)
432{
433 if (n->num_snaps == 0)
434 return false;
435 /* snaps are in descending order */
436 return n->snaps[0] > o->seq;
437}
438
439/*
440 * When a snapshot is applied, the size/mtime inode metadata is queued
441 * in a ceph_cap_snap (one for each snapshot) until writeback
442 * completes and the metadata can be flushed back to the MDS.
443 *
444 * However, if a (sync) write is currently in-progress when we apply
445 * the snapshot, we have to wait until the write succeeds or fails
446 * (and a final size/mtime is known). In this case the
447 * cap_snap->writing = 1, and is said to be "pending." When the write
448 * finishes, we __ceph_finish_cap_snap().
449 *
450 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
451 * change).
452 */
453void ceph_queue_cap_snap(struct ceph_inode_info *ci)
454{
455 struct inode *inode = &ci->vfs_inode;
456 struct ceph_cap_snap *capsnap;
457 struct ceph_snap_context *old_snapc, *new_snapc;
458 int used, dirty;
459
460 capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
461 if (!capsnap) {
462 pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
463 return;
464 }
465
466 spin_lock(&ci->i_ceph_lock);
467 used = __ceph_caps_used(ci);
468 dirty = __ceph_caps_dirty(ci);
469
470 old_snapc = ci->i_head_snapc;
471 new_snapc = ci->i_snap_realm->cached_context;
472
473 /*
474 * If there is a write in progress, treat that as a dirty Fw,
475 * even though it hasn't completed yet; by the time we finish
476 * up this capsnap it will be.
477 */
478 if (used & CEPH_CAP_FILE_WR)
479 dirty |= CEPH_CAP_FILE_WR;
480
481 if (__ceph_have_pending_cap_snap(ci)) {
482 /* there is no point in queuing multiple "pending" cap_snaps,
483 as no new writes are allowed to start when pending, so any
484 writes in progress now were started before the previous
485 cap_snap. lucky us. */
486 dout("queue_cap_snap %p already pending\n", inode);
487 goto update_snapc;
488 }
489 if (ci->i_wrbuffer_ref_head == 0 &&
490 !(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) {
491 dout("queue_cap_snap %p nothing dirty|writing\n", inode);
492 goto update_snapc;
493 }
494
495 BUG_ON(!old_snapc);
496
497 /*
498 * There is no need to send FLUSHSNAP message to MDS if there is
499 * no new snapshot. But when there is dirty pages or on-going
500 * writes, we still need to create cap_snap. cap_snap is needed
501 * by the write path and page writeback path.
502 *
503 * also see ceph_try_drop_cap_snap()
504 */
505 if (has_new_snaps(old_snapc, new_snapc)) {
506 if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))
507 capsnap->need_flush = true;
508 } else {
509 if (!(used & CEPH_CAP_FILE_WR) &&
510 ci->i_wrbuffer_ref_head == 0) {
511 dout("queue_cap_snap %p "
512 "no new_snap|dirty_page|writing\n", inode);
513 goto update_snapc;
514 }
515 }
516
517 dout("queue_cap_snap %p cap_snap %p queuing under %p %s %s\n",
518 inode, capsnap, old_snapc, ceph_cap_string(dirty),
519 capsnap->need_flush ? "" : "no_flush");
520 ihold(inode);
521
522 atomic_set(&capsnap->nref, 1);
523 capsnap->ci = ci;
524 INIT_LIST_HEAD(&capsnap->ci_item);
525 INIT_LIST_HEAD(&capsnap->flushing_item);
526
527 capsnap->follows = old_snapc->seq;
528 capsnap->issued = __ceph_caps_issued(ci, NULL);
529 capsnap->dirty = dirty;
530
531 capsnap->mode = inode->i_mode;
532 capsnap->uid = inode->i_uid;
533 capsnap->gid = inode->i_gid;
534
535 if (dirty & CEPH_CAP_XATTR_EXCL) {
536 __ceph_build_xattrs_blob(ci);
537 capsnap->xattr_blob =
538 ceph_buffer_get(ci->i_xattrs.blob);
539 capsnap->xattr_version = ci->i_xattrs.version;
540 } else {
541 capsnap->xattr_blob = NULL;
542 capsnap->xattr_version = 0;
543 }
544
545 capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
546
547 /* dirty page count moved from _head to this cap_snap;
548 all subsequent writes page dirties occur _after_ this
549 snapshot. */
550 capsnap->dirty_pages = ci->i_wrbuffer_ref_head;
551 ci->i_wrbuffer_ref_head = 0;
552 capsnap->context = old_snapc;
553 list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);
554 old_snapc = NULL;
555
556 if (used & CEPH_CAP_FILE_WR) {
557 dout("queue_cap_snap %p cap_snap %p snapc %p"
558 " seq %llu used WR, now pending\n", inode,
559 capsnap, old_snapc, old_snapc->seq);
560 capsnap->writing = 1;
561 } else {
562 /* note mtime, size NOW. */
563 __ceph_finish_cap_snap(ci, capsnap);
564 }
565 capsnap = NULL;
566
567update_snapc:
568 if (ci->i_head_snapc) {
569 ci->i_head_snapc = ceph_get_snap_context(new_snapc);
570 dout(" new snapc is %p\n", new_snapc);
571 }
572 spin_unlock(&ci->i_ceph_lock);
573
574 kfree(capsnap);
575 ceph_put_snap_context(old_snapc);
576}
577
578/*
579 * Finalize the size, mtime for a cap_snap.. that is, settle on final values
580 * to be used for the snapshot, to be flushed back to the mds.
581 *
582 * If capsnap can now be flushed, add to snap_flush list, and return 1.
583 *
584 * Caller must hold i_ceph_lock.
585 */
586int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
587 struct ceph_cap_snap *capsnap)
588{
589 struct inode *inode = &ci->vfs_inode;
590 struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
591
592 BUG_ON(capsnap->writing);
593 capsnap->size = inode->i_size;
594 capsnap->mtime = inode->i_mtime;
595 capsnap->atime = inode->i_atime;
596 capsnap->ctime = inode->i_ctime;
597 capsnap->time_warp_seq = ci->i_time_warp_seq;
598 if (capsnap->dirty_pages) {
599 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
600 "still has %d dirty pages\n", inode, capsnap,
601 capsnap->context, capsnap->context->seq,
602 ceph_cap_string(capsnap->dirty), capsnap->size,
603 capsnap->dirty_pages);
604 return 0;
605 }
606 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
607 inode, capsnap, capsnap->context,
608 capsnap->context->seq, ceph_cap_string(capsnap->dirty),
609 capsnap->size);
610
611 spin_lock(&mdsc->snap_flush_lock);
612 list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
613 spin_unlock(&mdsc->snap_flush_lock);
614 return 1; /* caller may want to ceph_flush_snaps */
615}
616
617/*
618 * Queue cap_snaps for snap writeback for this realm and its children.
619 * Called under snap_rwsem, so realm topology won't change.
620 */
621static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
622{
623 struct ceph_inode_info *ci;
624 struct inode *lastinode = NULL;
625 struct ceph_snap_realm *child;
626
627 dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
628
629 spin_lock(&realm->inodes_with_caps_lock);
630 list_for_each_entry(ci, &realm->inodes_with_caps,
631 i_snap_realm_item) {
632 struct inode *inode = igrab(&ci->vfs_inode);
633 if (!inode)
634 continue;
635 spin_unlock(&realm->inodes_with_caps_lock);
636 iput(lastinode);
637 lastinode = inode;
638 ceph_queue_cap_snap(ci);
639 spin_lock(&realm->inodes_with_caps_lock);
640 }
641 spin_unlock(&realm->inodes_with_caps_lock);
642 iput(lastinode);
643
644 list_for_each_entry(child, &realm->children, child_item) {
645 dout("queue_realm_cap_snaps %p %llx queue child %p %llx\n",
646 realm, realm->ino, child, child->ino);
647 list_del_init(&child->dirty_item);
648 list_add(&child->dirty_item, &realm->dirty_item);
649 }
650
651 list_del_init(&realm->dirty_item);
652 dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
653}
654
655/*
656 * Parse and apply a snapblob "snap trace" from the MDS. This specifies
657 * the snap realm parameters from a given realm and all of its ancestors,
658 * up to the root.
659 *
660 * Caller must hold snap_rwsem for write.
661 */
662int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
663 void *p, void *e, bool deletion,
664 struct ceph_snap_realm **realm_ret)
665{
666 struct ceph_mds_snap_realm *ri; /* encoded */
667 __le64 *snaps; /* encoded */
668 __le64 *prior_parent_snaps; /* encoded */
669 struct ceph_snap_realm *realm = NULL;
670 struct ceph_snap_realm *first_realm = NULL;
671 int invalidate = 0;
672 int err = -ENOMEM;
673 LIST_HEAD(dirty_realms);
674
675 dout("update_snap_trace deletion=%d\n", deletion);
676more:
677 ceph_decode_need(&p, e, sizeof(*ri), bad);
678 ri = p;
679 p += sizeof(*ri);
680 ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
681 le32_to_cpu(ri->num_prior_parent_snaps)), bad);
682 snaps = p;
683 p += sizeof(u64) * le32_to_cpu(ri->num_snaps);
684 prior_parent_snaps = p;
685 p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps);
686
687 realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
688 if (!realm) {
689 realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
690 if (IS_ERR(realm)) {
691 err = PTR_ERR(realm);
692 goto fail;
693 }
694 }
695
696 /* ensure the parent is correct */
697 err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
698 if (err < 0)
699 goto fail;
700 invalidate += err;
701
702 if (le64_to_cpu(ri->seq) > realm->seq) {
703 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
704 realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
705 /* update realm parameters, snap lists */
706 realm->seq = le64_to_cpu(ri->seq);
707 realm->created = le64_to_cpu(ri->created);
708 realm->parent_since = le64_to_cpu(ri->parent_since);
709
710 realm->num_snaps = le32_to_cpu(ri->num_snaps);
711 err = dup_array(&realm->snaps, snaps, realm->num_snaps);
712 if (err < 0)
713 goto fail;
714
715 realm->num_prior_parent_snaps =
716 le32_to_cpu(ri->num_prior_parent_snaps);
717 err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps,
718 realm->num_prior_parent_snaps);
719 if (err < 0)
720 goto fail;
721
722 /* queue realm for cap_snap creation */
723 list_add(&realm->dirty_item, &dirty_realms);
724 if (realm->seq > mdsc->last_snap_seq)
725 mdsc->last_snap_seq = realm->seq;
726
727 invalidate = 1;
728 } else if (!realm->cached_context) {
729 dout("update_snap_trace %llx %p seq %lld new\n",
730 realm->ino, realm, realm->seq);
731 invalidate = 1;
732 } else {
733 dout("update_snap_trace %llx %p seq %lld unchanged\n",
734 realm->ino, realm, realm->seq);
735 }
736
737 dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
738 realm, invalidate, p, e);
739
740 /* invalidate when we reach the _end_ (root) of the trace */
741 if (invalidate && p >= e)
742 rebuild_snap_realms(realm);
743
744 if (!first_realm)
745 first_realm = realm;
746 else
747 ceph_put_snap_realm(mdsc, realm);
748
749 if (p < e)
750 goto more;
751
752 /*
753 * queue cap snaps _after_ we've built the new snap contexts,
754 * so that i_head_snapc can be set appropriately.
755 */
756 while (!list_empty(&dirty_realms)) {
757 realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
758 dirty_item);
759 queue_realm_cap_snaps(realm);
760 }
761
762 if (realm_ret)
763 *realm_ret = first_realm;
764 else
765 ceph_put_snap_realm(mdsc, first_realm);
766
767 __cleanup_empty_realms(mdsc);
768 return 0;
769
770bad:
771 err = -EINVAL;
772fail:
773 if (realm && !IS_ERR(realm))
774 ceph_put_snap_realm(mdsc, realm);
775 if (first_realm)
776 ceph_put_snap_realm(mdsc, first_realm);
777 pr_err("update_snap_trace error %d\n", err);
778 return err;
779}
780
781
782/*
783 * Send any cap_snaps that are queued for flush. Try to carry
784 * s_mutex across multiple snap flushes to avoid locking overhead.
785 *
786 * Caller holds no locks.
787 */
788static void flush_snaps(struct ceph_mds_client *mdsc)
789{
790 struct ceph_inode_info *ci;
791 struct inode *inode;
792 struct ceph_mds_session *session = NULL;
793
794 dout("flush_snaps\n");
795 spin_lock(&mdsc->snap_flush_lock);
796 while (!list_empty(&mdsc->snap_flush_list)) {
797 ci = list_first_entry(&mdsc->snap_flush_list,
798 struct ceph_inode_info, i_snap_flush_item);
799 inode = &ci->vfs_inode;
800 ihold(inode);
801 spin_unlock(&mdsc->snap_flush_lock);
802 spin_lock(&ci->i_ceph_lock);
803 __ceph_flush_snaps(ci, &session, 0);
804 spin_unlock(&ci->i_ceph_lock);
805 iput(inode);
806 spin_lock(&mdsc->snap_flush_lock);
807 }
808 spin_unlock(&mdsc->snap_flush_lock);
809
810 if (session) {
811 mutex_unlock(&session->s_mutex);
812 ceph_put_mds_session(session);
813 }
814 dout("flush_snaps done\n");
815}
816
817
818/*
819 * Handle a snap notification from the MDS.
820 *
821 * This can take two basic forms: the simplest is just a snap creation
822 * or deletion notification on an existing realm. This should update the
823 * realm and its children.
824 *
825 * The more difficult case is realm creation, due to snap creation at a
826 * new point in the file hierarchy, or due to a rename that moves a file or
827 * directory into another realm.
828 */
829void ceph_handle_snap(struct ceph_mds_client *mdsc,
830 struct ceph_mds_session *session,
831 struct ceph_msg *msg)
832{
833 struct super_block *sb = mdsc->fsc->sb;
834 int mds = session->s_mds;
835 u64 split;
836 int op;
837 int trace_len;
838 struct ceph_snap_realm *realm = NULL;
839 void *p = msg->front.iov_base;
840 void *e = p + msg->front.iov_len;
841 struct ceph_mds_snap_head *h;
842 int num_split_inos, num_split_realms;
843 __le64 *split_inos = NULL, *split_realms = NULL;
844 int i;
845 int locked_rwsem = 0;
846
847 /* decode */
848 if (msg->front.iov_len < sizeof(*h))
849 goto bad;
850 h = p;
851 op = le32_to_cpu(h->op);
852 split = le64_to_cpu(h->split); /* non-zero if we are splitting an
853 * existing realm */
854 num_split_inos = le32_to_cpu(h->num_split_inos);
855 num_split_realms = le32_to_cpu(h->num_split_realms);
856 trace_len = le32_to_cpu(h->trace_len);
857 p += sizeof(*h);
858
859 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds,
860 ceph_snap_op_name(op), split, trace_len);
861
862 mutex_lock(&session->s_mutex);
863 session->s_seq++;
864 mutex_unlock(&session->s_mutex);
865
866 down_write(&mdsc->snap_rwsem);
867 locked_rwsem = 1;
868
869 if (op == CEPH_SNAP_OP_SPLIT) {
870 struct ceph_mds_snap_realm *ri;
871
872 /*
873 * A "split" breaks part of an existing realm off into
874 * a new realm. The MDS provides a list of inodes
875 * (with caps) and child realms that belong to the new
876 * child.
877 */
878 split_inos = p;
879 p += sizeof(u64) * num_split_inos;
880 split_realms = p;
881 p += sizeof(u64) * num_split_realms;
882 ceph_decode_need(&p, e, sizeof(*ri), bad);
883 /* we will peek at realm info here, but will _not_
884 * advance p, as the realm update will occur below in
885 * ceph_update_snap_trace. */
886 ri = p;
887
888 realm = ceph_lookup_snap_realm(mdsc, split);
889 if (!realm) {
890 realm = ceph_create_snap_realm(mdsc, split);
891 if (IS_ERR(realm))
892 goto out;
893 }
894
895 dout("splitting snap_realm %llx %p\n", realm->ino, realm);
896 for (i = 0; i < num_split_inos; i++) {
897 struct ceph_vino vino = {
898 .ino = le64_to_cpu(split_inos[i]),
899 .snap = CEPH_NOSNAP,
900 };
901 struct inode *inode = ceph_find_inode(sb, vino);
902 struct ceph_inode_info *ci;
903 struct ceph_snap_realm *oldrealm;
904
905 if (!inode)
906 continue;
907 ci = ceph_inode(inode);
908
909 spin_lock(&ci->i_ceph_lock);
910 if (!ci->i_snap_realm)
911 goto skip_inode;
912 /*
913 * If this inode belongs to a realm that was
914 * created after our new realm, we experienced
915 * a race (due to another split notifications
916 * arriving from a different MDS). So skip
917 * this inode.
918 */
919 if (ci->i_snap_realm->created >
920 le64_to_cpu(ri->created)) {
921 dout(" leaving %p in newer realm %llx %p\n",
922 inode, ci->i_snap_realm->ino,
923 ci->i_snap_realm);
924 goto skip_inode;
925 }
926 dout(" will move %p to split realm %llx %p\n",
927 inode, realm->ino, realm);
928 /*
929 * Move the inode to the new realm
930 */
931 spin_lock(&realm->inodes_with_caps_lock);
932 list_del_init(&ci->i_snap_realm_item);
933 list_add(&ci->i_snap_realm_item,
934 &realm->inodes_with_caps);
935 oldrealm = ci->i_snap_realm;
936 ci->i_snap_realm = realm;
937 spin_unlock(&realm->inodes_with_caps_lock);
938 spin_unlock(&ci->i_ceph_lock);
939
940 ceph_get_snap_realm(mdsc, realm);
941 ceph_put_snap_realm(mdsc, oldrealm);
942
943 iput(inode);
944 continue;
945
946skip_inode:
947 spin_unlock(&ci->i_ceph_lock);
948 iput(inode);
949 }
950
951 /* we may have taken some of the old realm's children. */
952 for (i = 0; i < num_split_realms; i++) {
953 struct ceph_snap_realm *child =
954 __lookup_snap_realm(mdsc,
955 le64_to_cpu(split_realms[i]));
956 if (!child)
957 continue;
958 adjust_snap_realm_parent(mdsc, child, realm->ino);
959 }
960 }
961
962 /*
963 * update using the provided snap trace. if we are deleting a
964 * snap, we can avoid queueing cap_snaps.
965 */
966 ceph_update_snap_trace(mdsc, p, e,
967 op == CEPH_SNAP_OP_DESTROY, NULL);
968
969 if (op == CEPH_SNAP_OP_SPLIT)
970 /* we took a reference when we created the realm, above */
971 ceph_put_snap_realm(mdsc, realm);
972
973 __cleanup_empty_realms(mdsc);
974
975 up_write(&mdsc->snap_rwsem);
976
977 flush_snaps(mdsc);
978 return;
979
980bad:
981 pr_err("corrupt snap message from mds%d\n", mds);
982 ceph_msg_dump(msg);
983out:
984 if (locked_rwsem)
985 up_write(&mdsc->snap_rwsem);
986 return;
987}
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/ceph/ceph_debug.h>
3
4#include <linux/sort.h>
5#include <linux/slab.h>
6#include <linux/iversion.h>
7#include "super.h"
8#include "mds_client.h"
9#include <linux/ceph/decode.h>
10
11/* unused map expires after 5 minutes */
12#define CEPH_SNAPID_MAP_TIMEOUT (5 * 60 * HZ)
13
14/*
15 * Snapshots in ceph are driven in large part by cooperation from the
16 * client. In contrast to local file systems or file servers that
17 * implement snapshots at a single point in the system, ceph's
18 * distributed access to storage requires clients to help decide
19 * whether a write logically occurs before or after a recently created
20 * snapshot.
21 *
22 * This provides a perfect instantanous client-wide snapshot. Between
23 * clients, however, snapshots may appear to be applied at slightly
24 * different points in time, depending on delays in delivering the
25 * snapshot notification.
26 *
27 * Snapshots are _not_ file system-wide. Instead, each snapshot
28 * applies to the subdirectory nested beneath some directory. This
29 * effectively divides the hierarchy into multiple "realms," where all
30 * of the files contained by each realm share the same set of
31 * snapshots. An individual realm's snap set contains snapshots
32 * explicitly created on that realm, as well as any snaps in its
33 * parent's snap set _after_ the point at which the parent became it's
34 * parent (due to, say, a rename). Similarly, snaps from prior parents
35 * during the time intervals during which they were the parent are included.
36 *
37 * The client is spared most of this detail, fortunately... it must only
38 * maintains a hierarchy of realms reflecting the current parent/child
39 * realm relationship, and for each realm has an explicit list of snaps
40 * inherited from prior parents.
41 *
42 * A snap_realm struct is maintained for realms containing every inode
43 * with an open cap in the system. (The needed snap realm information is
44 * provided by the MDS whenever a cap is issued, i.e., on open.) A 'seq'
45 * version number is used to ensure that as realm parameters change (new
46 * snapshot, new parent, etc.) the client's realm hierarchy is updated.
47 *
48 * The realm hierarchy drives the generation of a 'snap context' for each
49 * realm, which simply lists the resulting set of snaps for the realm. This
50 * is attached to any writes sent to OSDs.
51 */
52/*
53 * Unfortunately error handling is a bit mixed here. If we get a snap
54 * update, but don't have enough memory to update our realm hierarchy,
55 * it's not clear what we can do about it (besides complaining to the
56 * console).
57 */
58
59
60/*
61 * increase ref count for the realm
62 *
63 * caller must hold snap_rwsem.
64 */
65void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
66 struct ceph_snap_realm *realm)
67{
68 lockdep_assert_held(&mdsc->snap_rwsem);
69
70 /*
71 * The 0->1 and 1->0 transitions must take the snap_empty_lock
72 * atomically with the refcount change. Go ahead and bump the
73 * nref here, unless it's 0, in which case we take the spinlock
74 * and then do the increment and remove it from the list.
75 */
76 if (atomic_inc_not_zero(&realm->nref))
77 return;
78
79 spin_lock(&mdsc->snap_empty_lock);
80 if (atomic_inc_return(&realm->nref) == 1)
81 list_del_init(&realm->empty_item);
82 spin_unlock(&mdsc->snap_empty_lock);
83}
84
85static void __insert_snap_realm(struct rb_root *root,
86 struct ceph_snap_realm *new)
87{
88 struct rb_node **p = &root->rb_node;
89 struct rb_node *parent = NULL;
90 struct ceph_snap_realm *r = NULL;
91
92 while (*p) {
93 parent = *p;
94 r = rb_entry(parent, struct ceph_snap_realm, node);
95 if (new->ino < r->ino)
96 p = &(*p)->rb_left;
97 else if (new->ino > r->ino)
98 p = &(*p)->rb_right;
99 else
100 BUG();
101 }
102
103 rb_link_node(&new->node, parent, p);
104 rb_insert_color(&new->node, root);
105}
106
107/*
108 * create and get the realm rooted at @ino and bump its ref count.
109 *
110 * caller must hold snap_rwsem for write.
111 */
112static struct ceph_snap_realm *ceph_create_snap_realm(
113 struct ceph_mds_client *mdsc,
114 u64 ino)
115{
116 struct ceph_snap_realm *realm;
117
118 lockdep_assert_held_write(&mdsc->snap_rwsem);
119
120 realm = kzalloc(sizeof(*realm), GFP_NOFS);
121 if (!realm)
122 return ERR_PTR(-ENOMEM);
123
124 atomic_set(&realm->nref, 1); /* for caller */
125 realm->ino = ino;
126 INIT_LIST_HEAD(&realm->children);
127 INIT_LIST_HEAD(&realm->child_item);
128 INIT_LIST_HEAD(&realm->empty_item);
129 INIT_LIST_HEAD(&realm->dirty_item);
130 INIT_LIST_HEAD(&realm->inodes_with_caps);
131 spin_lock_init(&realm->inodes_with_caps_lock);
132 __insert_snap_realm(&mdsc->snap_realms, realm);
133 mdsc->num_snap_realms++;
134
135 dout("create_snap_realm %llx %p\n", realm->ino, realm);
136 return realm;
137}
138
139/*
140 * lookup the realm rooted at @ino.
141 *
142 * caller must hold snap_rwsem.
143 */
144static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
145 u64 ino)
146{
147 struct rb_node *n = mdsc->snap_realms.rb_node;
148 struct ceph_snap_realm *r;
149
150 lockdep_assert_held(&mdsc->snap_rwsem);
151
152 while (n) {
153 r = rb_entry(n, struct ceph_snap_realm, node);
154 if (ino < r->ino)
155 n = n->rb_left;
156 else if (ino > r->ino)
157 n = n->rb_right;
158 else {
159 dout("lookup_snap_realm %llx %p\n", r->ino, r);
160 return r;
161 }
162 }
163 return NULL;
164}
165
166struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
167 u64 ino)
168{
169 struct ceph_snap_realm *r;
170 r = __lookup_snap_realm(mdsc, ino);
171 if (r)
172 ceph_get_snap_realm(mdsc, r);
173 return r;
174}
175
176static void __put_snap_realm(struct ceph_mds_client *mdsc,
177 struct ceph_snap_realm *realm);
178
179/*
180 * called with snap_rwsem (write)
181 */
182static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
183 struct ceph_snap_realm *realm)
184{
185 lockdep_assert_held_write(&mdsc->snap_rwsem);
186
187 dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
188
189 rb_erase(&realm->node, &mdsc->snap_realms);
190 mdsc->num_snap_realms--;
191
192 if (realm->parent) {
193 list_del_init(&realm->child_item);
194 __put_snap_realm(mdsc, realm->parent);
195 }
196
197 kfree(realm->prior_parent_snaps);
198 kfree(realm->snaps);
199 ceph_put_snap_context(realm->cached_context);
200 kfree(realm);
201}
202
203/*
204 * caller holds snap_rwsem (write)
205 */
206static void __put_snap_realm(struct ceph_mds_client *mdsc,
207 struct ceph_snap_realm *realm)
208{
209 lockdep_assert_held_write(&mdsc->snap_rwsem);
210
211 /*
212 * We do not require the snap_empty_lock here, as any caller that
213 * increments the value must hold the snap_rwsem.
214 */
215 if (atomic_dec_and_test(&realm->nref))
216 __destroy_snap_realm(mdsc, realm);
217}
218
219/*
220 * See comments in ceph_get_snap_realm. Caller needn't hold any locks.
221 */
222void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
223 struct ceph_snap_realm *realm)
224{
225 if (!atomic_dec_and_lock(&realm->nref, &mdsc->snap_empty_lock))
226 return;
227
228 if (down_write_trylock(&mdsc->snap_rwsem)) {
229 spin_unlock(&mdsc->snap_empty_lock);
230 __destroy_snap_realm(mdsc, realm);
231 up_write(&mdsc->snap_rwsem);
232 } else {
233 list_add(&realm->empty_item, &mdsc->snap_empty);
234 spin_unlock(&mdsc->snap_empty_lock);
235 }
236}
237
238/*
239 * Clean up any realms whose ref counts have dropped to zero. Note
240 * that this does not include realms who were created but not yet
241 * used.
242 *
243 * Called under snap_rwsem (write)
244 */
245static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
246{
247 struct ceph_snap_realm *realm;
248
249 lockdep_assert_held_write(&mdsc->snap_rwsem);
250
251 spin_lock(&mdsc->snap_empty_lock);
252 while (!list_empty(&mdsc->snap_empty)) {
253 realm = list_first_entry(&mdsc->snap_empty,
254 struct ceph_snap_realm, empty_item);
255 list_del(&realm->empty_item);
256 spin_unlock(&mdsc->snap_empty_lock);
257 __destroy_snap_realm(mdsc, realm);
258 spin_lock(&mdsc->snap_empty_lock);
259 }
260 spin_unlock(&mdsc->snap_empty_lock);
261}
262
263void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc)
264{
265 down_write(&mdsc->snap_rwsem);
266 __cleanup_empty_realms(mdsc);
267 up_write(&mdsc->snap_rwsem);
268}
269
270/*
271 * adjust the parent realm of a given @realm. adjust child list, and parent
272 * pointers, and ref counts appropriately.
273 *
274 * return true if parent was changed, 0 if unchanged, <0 on error.
275 *
276 * caller must hold snap_rwsem for write.
277 */
278static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
279 struct ceph_snap_realm *realm,
280 u64 parentino)
281{
282 struct ceph_snap_realm *parent;
283
284 lockdep_assert_held_write(&mdsc->snap_rwsem);
285
286 if (realm->parent_ino == parentino)
287 return 0;
288
289 parent = ceph_lookup_snap_realm(mdsc, parentino);
290 if (!parent) {
291 parent = ceph_create_snap_realm(mdsc, parentino);
292 if (IS_ERR(parent))
293 return PTR_ERR(parent);
294 }
295 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
296 realm->ino, realm, realm->parent_ino, realm->parent,
297 parentino, parent);
298 if (realm->parent) {
299 list_del_init(&realm->child_item);
300 ceph_put_snap_realm(mdsc, realm->parent);
301 }
302 realm->parent_ino = parentino;
303 realm->parent = parent;
304 list_add(&realm->child_item, &parent->children);
305 return 1;
306}
307
308
309static int cmpu64_rev(const void *a, const void *b)
310{
311 if (*(u64 *)a < *(u64 *)b)
312 return 1;
313 if (*(u64 *)a > *(u64 *)b)
314 return -1;
315 return 0;
316}
317
318
319/*
320 * build the snap context for a given realm.
321 */
322static int build_snap_context(struct ceph_snap_realm *realm,
323 struct list_head* dirty_realms)
324{
325 struct ceph_snap_realm *parent = realm->parent;
326 struct ceph_snap_context *snapc;
327 int err = 0;
328 u32 num = realm->num_prior_parent_snaps + realm->num_snaps;
329
330 /*
331 * build parent context, if it hasn't been built.
332 * conservatively estimate that all parent snaps might be
333 * included by us.
334 */
335 if (parent) {
336 if (!parent->cached_context) {
337 err = build_snap_context(parent, dirty_realms);
338 if (err)
339 goto fail;
340 }
341 num += parent->cached_context->num_snaps;
342 }
343
344 /* do i actually need to update? not if my context seq
345 matches realm seq, and my parents' does to. (this works
346 because we rebuild_snap_realms() works _downward_ in
347 hierarchy after each update.) */
348 if (realm->cached_context &&
349 realm->cached_context->seq == realm->seq &&
350 (!parent ||
351 realm->cached_context->seq >= parent->cached_context->seq)) {
352 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)"
353 " (unchanged)\n",
354 realm->ino, realm, realm->cached_context,
355 realm->cached_context->seq,
356 (unsigned int)realm->cached_context->num_snaps);
357 return 0;
358 }
359
360 /* alloc new snap context */
361 err = -ENOMEM;
362 if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
363 goto fail;
364 snapc = ceph_create_snap_context(num, GFP_NOFS);
365 if (!snapc)
366 goto fail;
367
368 /* build (reverse sorted) snap vector */
369 num = 0;
370 snapc->seq = realm->seq;
371 if (parent) {
372 u32 i;
373
374 /* include any of parent's snaps occurring _after_ my
375 parent became my parent */
376 for (i = 0; i < parent->cached_context->num_snaps; i++)
377 if (parent->cached_context->snaps[i] >=
378 realm->parent_since)
379 snapc->snaps[num++] =
380 parent->cached_context->snaps[i];
381 if (parent->cached_context->seq > snapc->seq)
382 snapc->seq = parent->cached_context->seq;
383 }
384 memcpy(snapc->snaps + num, realm->snaps,
385 sizeof(u64)*realm->num_snaps);
386 num += realm->num_snaps;
387 memcpy(snapc->snaps + num, realm->prior_parent_snaps,
388 sizeof(u64)*realm->num_prior_parent_snaps);
389 num += realm->num_prior_parent_snaps;
390
391 sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL);
392 snapc->num_snaps = num;
393 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)\n",
394 realm->ino, realm, snapc, snapc->seq,
395 (unsigned int) snapc->num_snaps);
396
397 ceph_put_snap_context(realm->cached_context);
398 realm->cached_context = snapc;
399 /* queue realm for cap_snap creation */
400 list_add_tail(&realm->dirty_item, dirty_realms);
401 return 0;
402
403fail:
404 /*
405 * if we fail, clear old (incorrect) cached_context... hopefully
406 * we'll have better luck building it later
407 */
408 if (realm->cached_context) {
409 ceph_put_snap_context(realm->cached_context);
410 realm->cached_context = NULL;
411 }
412 pr_err("build_snap_context %llx %p fail %d\n", realm->ino,
413 realm, err);
414 return err;
415}
416
417/*
418 * rebuild snap context for the given realm and all of its children.
419 */
420static void rebuild_snap_realms(struct ceph_snap_realm *realm,
421 struct list_head *dirty_realms)
422{
423 struct ceph_snap_realm *child;
424
425 dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
426 build_snap_context(realm, dirty_realms);
427
428 list_for_each_entry(child, &realm->children, child_item)
429 rebuild_snap_realms(child, dirty_realms);
430}
431
432
433/*
434 * helper to allocate and decode an array of snapids. free prior
435 * instance, if any.
436 */
437static int dup_array(u64 **dst, __le64 *src, u32 num)
438{
439 u32 i;
440
441 kfree(*dst);
442 if (num) {
443 *dst = kcalloc(num, sizeof(u64), GFP_NOFS);
444 if (!*dst)
445 return -ENOMEM;
446 for (i = 0; i < num; i++)
447 (*dst)[i] = get_unaligned_le64(src + i);
448 } else {
449 *dst = NULL;
450 }
451 return 0;
452}
453
454static bool has_new_snaps(struct ceph_snap_context *o,
455 struct ceph_snap_context *n)
456{
457 if (n->num_snaps == 0)
458 return false;
459 /* snaps are in descending order */
460 return n->snaps[0] > o->seq;
461}
462
463/*
464 * When a snapshot is applied, the size/mtime inode metadata is queued
465 * in a ceph_cap_snap (one for each snapshot) until writeback
466 * completes and the metadata can be flushed back to the MDS.
467 *
468 * However, if a (sync) write is currently in-progress when we apply
469 * the snapshot, we have to wait until the write succeeds or fails
470 * (and a final size/mtime is known). In this case the
471 * cap_snap->writing = 1, and is said to be "pending." When the write
472 * finishes, we __ceph_finish_cap_snap().
473 *
474 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
475 * change).
476 */
477static void ceph_queue_cap_snap(struct ceph_inode_info *ci)
478{
479 struct inode *inode = &ci->vfs_inode;
480 struct ceph_cap_snap *capsnap;
481 struct ceph_snap_context *old_snapc, *new_snapc;
482 struct ceph_buffer *old_blob = NULL;
483 int used, dirty;
484
485 capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
486 if (!capsnap) {
487 pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
488 return;
489 }
490 capsnap->cap_flush.is_capsnap = true;
491 INIT_LIST_HEAD(&capsnap->cap_flush.i_list);
492 INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
493
494 spin_lock(&ci->i_ceph_lock);
495 used = __ceph_caps_used(ci);
496 dirty = __ceph_caps_dirty(ci);
497
498 old_snapc = ci->i_head_snapc;
499 new_snapc = ci->i_snap_realm->cached_context;
500
501 /*
502 * If there is a write in progress, treat that as a dirty Fw,
503 * even though it hasn't completed yet; by the time we finish
504 * up this capsnap it will be.
505 */
506 if (used & CEPH_CAP_FILE_WR)
507 dirty |= CEPH_CAP_FILE_WR;
508
509 if (__ceph_have_pending_cap_snap(ci)) {
510 /* there is no point in queuing multiple "pending" cap_snaps,
511 as no new writes are allowed to start when pending, so any
512 writes in progress now were started before the previous
513 cap_snap. lucky us. */
514 dout("queue_cap_snap %p already pending\n", inode);
515 goto update_snapc;
516 }
517 if (ci->i_wrbuffer_ref_head == 0 &&
518 !(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) {
519 dout("queue_cap_snap %p nothing dirty|writing\n", inode);
520 goto update_snapc;
521 }
522
523 BUG_ON(!old_snapc);
524
525 /*
526 * There is no need to send FLUSHSNAP message to MDS if there is
527 * no new snapshot. But when there is dirty pages or on-going
528 * writes, we still need to create cap_snap. cap_snap is needed
529 * by the write path and page writeback path.
530 *
531 * also see ceph_try_drop_cap_snap()
532 */
533 if (has_new_snaps(old_snapc, new_snapc)) {
534 if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))
535 capsnap->need_flush = true;
536 } else {
537 if (!(used & CEPH_CAP_FILE_WR) &&
538 ci->i_wrbuffer_ref_head == 0) {
539 dout("queue_cap_snap %p "
540 "no new_snap|dirty_page|writing\n", inode);
541 goto update_snapc;
542 }
543 }
544
545 dout("queue_cap_snap %p cap_snap %p queuing under %p %s %s\n",
546 inode, capsnap, old_snapc, ceph_cap_string(dirty),
547 capsnap->need_flush ? "" : "no_flush");
548 ihold(inode);
549
550 refcount_set(&capsnap->nref, 1);
551 INIT_LIST_HEAD(&capsnap->ci_item);
552
553 capsnap->follows = old_snapc->seq;
554 capsnap->issued = __ceph_caps_issued(ci, NULL);
555 capsnap->dirty = dirty;
556
557 capsnap->mode = inode->i_mode;
558 capsnap->uid = inode->i_uid;
559 capsnap->gid = inode->i_gid;
560
561 if (dirty & CEPH_CAP_XATTR_EXCL) {
562 old_blob = __ceph_build_xattrs_blob(ci);
563 capsnap->xattr_blob =
564 ceph_buffer_get(ci->i_xattrs.blob);
565 capsnap->xattr_version = ci->i_xattrs.version;
566 } else {
567 capsnap->xattr_blob = NULL;
568 capsnap->xattr_version = 0;
569 }
570
571 capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
572
573 /* dirty page count moved from _head to this cap_snap;
574 all subsequent writes page dirties occur _after_ this
575 snapshot. */
576 capsnap->dirty_pages = ci->i_wrbuffer_ref_head;
577 ci->i_wrbuffer_ref_head = 0;
578 capsnap->context = old_snapc;
579 list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);
580
581 if (used & CEPH_CAP_FILE_WR) {
582 dout("queue_cap_snap %p cap_snap %p snapc %p"
583 " seq %llu used WR, now pending\n", inode,
584 capsnap, old_snapc, old_snapc->seq);
585 capsnap->writing = 1;
586 } else {
587 /* note mtime, size NOW. */
588 __ceph_finish_cap_snap(ci, capsnap);
589 }
590 capsnap = NULL;
591 old_snapc = NULL;
592
593update_snapc:
594 if (ci->i_wrbuffer_ref_head == 0 &&
595 ci->i_wr_ref == 0 &&
596 ci->i_dirty_caps == 0 &&
597 ci->i_flushing_caps == 0) {
598 ci->i_head_snapc = NULL;
599 } else {
600 ci->i_head_snapc = ceph_get_snap_context(new_snapc);
601 dout(" new snapc is %p\n", new_snapc);
602 }
603 spin_unlock(&ci->i_ceph_lock);
604
605 ceph_buffer_put(old_blob);
606 kfree(capsnap);
607 ceph_put_snap_context(old_snapc);
608}
609
610/*
611 * Finalize the size, mtime for a cap_snap.. that is, settle on final values
612 * to be used for the snapshot, to be flushed back to the mds.
613 *
614 * If capsnap can now be flushed, add to snap_flush list, and return 1.
615 *
616 * Caller must hold i_ceph_lock.
617 */
618int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
619 struct ceph_cap_snap *capsnap)
620{
621 struct inode *inode = &ci->vfs_inode;
622 struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
623
624 BUG_ON(capsnap->writing);
625 capsnap->size = i_size_read(inode);
626 capsnap->mtime = inode->i_mtime;
627 capsnap->atime = inode->i_atime;
628 capsnap->ctime = inode->i_ctime;
629 capsnap->btime = ci->i_btime;
630 capsnap->change_attr = inode_peek_iversion_raw(inode);
631 capsnap->time_warp_seq = ci->i_time_warp_seq;
632 capsnap->truncate_size = ci->i_truncate_size;
633 capsnap->truncate_seq = ci->i_truncate_seq;
634 if (capsnap->dirty_pages) {
635 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
636 "still has %d dirty pages\n", inode, capsnap,
637 capsnap->context, capsnap->context->seq,
638 ceph_cap_string(capsnap->dirty), capsnap->size,
639 capsnap->dirty_pages);
640 return 0;
641 }
642
643 /* Fb cap still in use, delay it */
644 if (ci->i_wb_ref) {
645 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
646 "used WRBUFFER, delaying\n", inode, capsnap,
647 capsnap->context, capsnap->context->seq,
648 ceph_cap_string(capsnap->dirty), capsnap->size);
649 capsnap->writing = 1;
650 return 0;
651 }
652
653 ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
654 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
655 inode, capsnap, capsnap->context,
656 capsnap->context->seq, ceph_cap_string(capsnap->dirty),
657 capsnap->size);
658
659 spin_lock(&mdsc->snap_flush_lock);
660 if (list_empty(&ci->i_snap_flush_item))
661 list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
662 spin_unlock(&mdsc->snap_flush_lock);
663 return 1; /* caller may want to ceph_flush_snaps */
664}
665
666/*
667 * Queue cap_snaps for snap writeback for this realm and its children.
668 * Called under snap_rwsem, so realm topology won't change.
669 */
670static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
671{
672 struct ceph_inode_info *ci;
673 struct inode *lastinode = NULL;
674
675 dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
676
677 spin_lock(&realm->inodes_with_caps_lock);
678 list_for_each_entry(ci, &realm->inodes_with_caps, i_snap_realm_item) {
679 struct inode *inode = igrab(&ci->vfs_inode);
680 if (!inode)
681 continue;
682 spin_unlock(&realm->inodes_with_caps_lock);
683 iput(lastinode);
684 lastinode = inode;
685 ceph_queue_cap_snap(ci);
686 spin_lock(&realm->inodes_with_caps_lock);
687 }
688 spin_unlock(&realm->inodes_with_caps_lock);
689 iput(lastinode);
690
691 dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
692}
693
694/*
695 * Parse and apply a snapblob "snap trace" from the MDS. This specifies
696 * the snap realm parameters from a given realm and all of its ancestors,
697 * up to the root.
698 *
699 * Caller must hold snap_rwsem for write.
700 */
701int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
702 void *p, void *e, bool deletion,
703 struct ceph_snap_realm **realm_ret)
704{
705 struct ceph_mds_snap_realm *ri; /* encoded */
706 __le64 *snaps; /* encoded */
707 __le64 *prior_parent_snaps; /* encoded */
708 struct ceph_snap_realm *realm = NULL;
709 struct ceph_snap_realm *first_realm = NULL;
710 int invalidate = 0;
711 int err = -ENOMEM;
712 LIST_HEAD(dirty_realms);
713
714 lockdep_assert_held_write(&mdsc->snap_rwsem);
715
716 dout("update_snap_trace deletion=%d\n", deletion);
717more:
718 ceph_decode_need(&p, e, sizeof(*ri), bad);
719 ri = p;
720 p += sizeof(*ri);
721 ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
722 le32_to_cpu(ri->num_prior_parent_snaps)), bad);
723 snaps = p;
724 p += sizeof(u64) * le32_to_cpu(ri->num_snaps);
725 prior_parent_snaps = p;
726 p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps);
727
728 realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
729 if (!realm) {
730 realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
731 if (IS_ERR(realm)) {
732 err = PTR_ERR(realm);
733 goto fail;
734 }
735 }
736
737 /* ensure the parent is correct */
738 err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
739 if (err < 0)
740 goto fail;
741 invalidate += err;
742
743 if (le64_to_cpu(ri->seq) > realm->seq) {
744 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
745 realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
746 /* update realm parameters, snap lists */
747 realm->seq = le64_to_cpu(ri->seq);
748 realm->created = le64_to_cpu(ri->created);
749 realm->parent_since = le64_to_cpu(ri->parent_since);
750
751 realm->num_snaps = le32_to_cpu(ri->num_snaps);
752 err = dup_array(&realm->snaps, snaps, realm->num_snaps);
753 if (err < 0)
754 goto fail;
755
756 realm->num_prior_parent_snaps =
757 le32_to_cpu(ri->num_prior_parent_snaps);
758 err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps,
759 realm->num_prior_parent_snaps);
760 if (err < 0)
761 goto fail;
762
763 if (realm->seq > mdsc->last_snap_seq)
764 mdsc->last_snap_seq = realm->seq;
765
766 invalidate = 1;
767 } else if (!realm->cached_context) {
768 dout("update_snap_trace %llx %p seq %lld new\n",
769 realm->ino, realm, realm->seq);
770 invalidate = 1;
771 } else {
772 dout("update_snap_trace %llx %p seq %lld unchanged\n",
773 realm->ino, realm, realm->seq);
774 }
775
776 dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
777 realm, invalidate, p, e);
778
779 /* invalidate when we reach the _end_ (root) of the trace */
780 if (invalidate && p >= e)
781 rebuild_snap_realms(realm, &dirty_realms);
782
783 if (!first_realm)
784 first_realm = realm;
785 else
786 ceph_put_snap_realm(mdsc, realm);
787
788 if (p < e)
789 goto more;
790
791 /*
792 * queue cap snaps _after_ we've built the new snap contexts,
793 * so that i_head_snapc can be set appropriately.
794 */
795 while (!list_empty(&dirty_realms)) {
796 realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
797 dirty_item);
798 list_del_init(&realm->dirty_item);
799 queue_realm_cap_snaps(realm);
800 }
801
802 if (realm_ret)
803 *realm_ret = first_realm;
804 else
805 ceph_put_snap_realm(mdsc, first_realm);
806
807 __cleanup_empty_realms(mdsc);
808 return 0;
809
810bad:
811 err = -EIO;
812fail:
813 if (realm && !IS_ERR(realm))
814 ceph_put_snap_realm(mdsc, realm);
815 if (first_realm)
816 ceph_put_snap_realm(mdsc, first_realm);
817 pr_err("update_snap_trace error %d\n", err);
818 return err;
819}
820
821
822/*
823 * Send any cap_snaps that are queued for flush. Try to carry
824 * s_mutex across multiple snap flushes to avoid locking overhead.
825 *
826 * Caller holds no locks.
827 */
828static void flush_snaps(struct ceph_mds_client *mdsc)
829{
830 struct ceph_inode_info *ci;
831 struct inode *inode;
832 struct ceph_mds_session *session = NULL;
833
834 dout("flush_snaps\n");
835 spin_lock(&mdsc->snap_flush_lock);
836 while (!list_empty(&mdsc->snap_flush_list)) {
837 ci = list_first_entry(&mdsc->snap_flush_list,
838 struct ceph_inode_info, i_snap_flush_item);
839 inode = &ci->vfs_inode;
840 ihold(inode);
841 spin_unlock(&mdsc->snap_flush_lock);
842 ceph_flush_snaps(ci, &session);
843 iput(inode);
844 spin_lock(&mdsc->snap_flush_lock);
845 }
846 spin_unlock(&mdsc->snap_flush_lock);
847
848 ceph_put_mds_session(session);
849 dout("flush_snaps done\n");
850}
851
852
853/*
854 * Handle a snap notification from the MDS.
855 *
856 * This can take two basic forms: the simplest is just a snap creation
857 * or deletion notification on an existing realm. This should update the
858 * realm and its children.
859 *
860 * The more difficult case is realm creation, due to snap creation at a
861 * new point in the file hierarchy, or due to a rename that moves a file or
862 * directory into another realm.
863 */
864void ceph_handle_snap(struct ceph_mds_client *mdsc,
865 struct ceph_mds_session *session,
866 struct ceph_msg *msg)
867{
868 struct super_block *sb = mdsc->fsc->sb;
869 int mds = session->s_mds;
870 u64 split;
871 int op;
872 int trace_len;
873 struct ceph_snap_realm *realm = NULL;
874 void *p = msg->front.iov_base;
875 void *e = p + msg->front.iov_len;
876 struct ceph_mds_snap_head *h;
877 int num_split_inos, num_split_realms;
878 __le64 *split_inos = NULL, *split_realms = NULL;
879 int i;
880 int locked_rwsem = 0;
881
882 /* decode */
883 if (msg->front.iov_len < sizeof(*h))
884 goto bad;
885 h = p;
886 op = le32_to_cpu(h->op);
887 split = le64_to_cpu(h->split); /* non-zero if we are splitting an
888 * existing realm */
889 num_split_inos = le32_to_cpu(h->num_split_inos);
890 num_split_realms = le32_to_cpu(h->num_split_realms);
891 trace_len = le32_to_cpu(h->trace_len);
892 p += sizeof(*h);
893
894 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds,
895 ceph_snap_op_name(op), split, trace_len);
896
897 mutex_lock(&session->s_mutex);
898 inc_session_sequence(session);
899 mutex_unlock(&session->s_mutex);
900
901 down_write(&mdsc->snap_rwsem);
902 locked_rwsem = 1;
903
904 if (op == CEPH_SNAP_OP_SPLIT) {
905 struct ceph_mds_snap_realm *ri;
906
907 /*
908 * A "split" breaks part of an existing realm off into
909 * a new realm. The MDS provides a list of inodes
910 * (with caps) and child realms that belong to the new
911 * child.
912 */
913 split_inos = p;
914 p += sizeof(u64) * num_split_inos;
915 split_realms = p;
916 p += sizeof(u64) * num_split_realms;
917 ceph_decode_need(&p, e, sizeof(*ri), bad);
918 /* we will peek at realm info here, but will _not_
919 * advance p, as the realm update will occur below in
920 * ceph_update_snap_trace. */
921 ri = p;
922
923 realm = ceph_lookup_snap_realm(mdsc, split);
924 if (!realm) {
925 realm = ceph_create_snap_realm(mdsc, split);
926 if (IS_ERR(realm))
927 goto out;
928 }
929
930 dout("splitting snap_realm %llx %p\n", realm->ino, realm);
931 for (i = 0; i < num_split_inos; i++) {
932 struct ceph_vino vino = {
933 .ino = le64_to_cpu(split_inos[i]),
934 .snap = CEPH_NOSNAP,
935 };
936 struct inode *inode = ceph_find_inode(sb, vino);
937 struct ceph_inode_info *ci;
938 struct ceph_snap_realm *oldrealm;
939
940 if (!inode)
941 continue;
942 ci = ceph_inode(inode);
943
944 spin_lock(&ci->i_ceph_lock);
945 if (!ci->i_snap_realm)
946 goto skip_inode;
947 /*
948 * If this inode belongs to a realm that was
949 * created after our new realm, we experienced
950 * a race (due to another split notifications
951 * arriving from a different MDS). So skip
952 * this inode.
953 */
954 if (ci->i_snap_realm->created >
955 le64_to_cpu(ri->created)) {
956 dout(" leaving %p in newer realm %llx %p\n",
957 inode, ci->i_snap_realm->ino,
958 ci->i_snap_realm);
959 goto skip_inode;
960 }
961 dout(" will move %p to split realm %llx %p\n",
962 inode, realm->ino, realm);
963 /*
964 * Move the inode to the new realm
965 */
966 oldrealm = ci->i_snap_realm;
967 spin_lock(&oldrealm->inodes_with_caps_lock);
968 list_del_init(&ci->i_snap_realm_item);
969 spin_unlock(&oldrealm->inodes_with_caps_lock);
970
971 spin_lock(&realm->inodes_with_caps_lock);
972 list_add(&ci->i_snap_realm_item,
973 &realm->inodes_with_caps);
974 ci->i_snap_realm = realm;
975 if (realm->ino == ci->i_vino.ino)
976 realm->inode = inode;
977 spin_unlock(&realm->inodes_with_caps_lock);
978
979 spin_unlock(&ci->i_ceph_lock);
980
981 ceph_get_snap_realm(mdsc, realm);
982 ceph_put_snap_realm(mdsc, oldrealm);
983
984 iput(inode);
985 continue;
986
987skip_inode:
988 spin_unlock(&ci->i_ceph_lock);
989 iput(inode);
990 }
991
992 /* we may have taken some of the old realm's children. */
993 for (i = 0; i < num_split_realms; i++) {
994 struct ceph_snap_realm *child =
995 __lookup_snap_realm(mdsc,
996 le64_to_cpu(split_realms[i]));
997 if (!child)
998 continue;
999 adjust_snap_realm_parent(mdsc, child, realm->ino);
1000 }
1001 }
1002
1003 /*
1004 * update using the provided snap trace. if we are deleting a
1005 * snap, we can avoid queueing cap_snaps.
1006 */
1007 ceph_update_snap_trace(mdsc, p, e,
1008 op == CEPH_SNAP_OP_DESTROY, NULL);
1009
1010 if (op == CEPH_SNAP_OP_SPLIT)
1011 /* we took a reference when we created the realm, above */
1012 ceph_put_snap_realm(mdsc, realm);
1013
1014 __cleanup_empty_realms(mdsc);
1015
1016 up_write(&mdsc->snap_rwsem);
1017
1018 flush_snaps(mdsc);
1019 return;
1020
1021bad:
1022 pr_err("corrupt snap message from mds%d\n", mds);
1023 ceph_msg_dump(msg);
1024out:
1025 if (locked_rwsem)
1026 up_write(&mdsc->snap_rwsem);
1027 return;
1028}
1029
1030struct ceph_snapid_map* ceph_get_snapid_map(struct ceph_mds_client *mdsc,
1031 u64 snap)
1032{
1033 struct ceph_snapid_map *sm, *exist;
1034 struct rb_node **p, *parent;
1035 int ret;
1036
1037 exist = NULL;
1038 spin_lock(&mdsc->snapid_map_lock);
1039 p = &mdsc->snapid_map_tree.rb_node;
1040 while (*p) {
1041 exist = rb_entry(*p, struct ceph_snapid_map, node);
1042 if (snap > exist->snap) {
1043 p = &(*p)->rb_left;
1044 } else if (snap < exist->snap) {
1045 p = &(*p)->rb_right;
1046 } else {
1047 if (atomic_inc_return(&exist->ref) == 1)
1048 list_del_init(&exist->lru);
1049 break;
1050 }
1051 exist = NULL;
1052 }
1053 spin_unlock(&mdsc->snapid_map_lock);
1054 if (exist) {
1055 dout("found snapid map %llx -> %x\n", exist->snap, exist->dev);
1056 return exist;
1057 }
1058
1059 sm = kmalloc(sizeof(*sm), GFP_NOFS);
1060 if (!sm)
1061 return NULL;
1062
1063 ret = get_anon_bdev(&sm->dev);
1064 if (ret < 0) {
1065 kfree(sm);
1066 return NULL;
1067 }
1068
1069 INIT_LIST_HEAD(&sm->lru);
1070 atomic_set(&sm->ref, 1);
1071 sm->snap = snap;
1072
1073 exist = NULL;
1074 parent = NULL;
1075 p = &mdsc->snapid_map_tree.rb_node;
1076 spin_lock(&mdsc->snapid_map_lock);
1077 while (*p) {
1078 parent = *p;
1079 exist = rb_entry(*p, struct ceph_snapid_map, node);
1080 if (snap > exist->snap)
1081 p = &(*p)->rb_left;
1082 else if (snap < exist->snap)
1083 p = &(*p)->rb_right;
1084 else
1085 break;
1086 exist = NULL;
1087 }
1088 if (exist) {
1089 if (atomic_inc_return(&exist->ref) == 1)
1090 list_del_init(&exist->lru);
1091 } else {
1092 rb_link_node(&sm->node, parent, p);
1093 rb_insert_color(&sm->node, &mdsc->snapid_map_tree);
1094 }
1095 spin_unlock(&mdsc->snapid_map_lock);
1096 if (exist) {
1097 free_anon_bdev(sm->dev);
1098 kfree(sm);
1099 dout("found snapid map %llx -> %x\n", exist->snap, exist->dev);
1100 return exist;
1101 }
1102
1103 dout("create snapid map %llx -> %x\n", sm->snap, sm->dev);
1104 return sm;
1105}
1106
1107void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
1108 struct ceph_snapid_map *sm)
1109{
1110 if (!sm)
1111 return;
1112 if (atomic_dec_and_lock(&sm->ref, &mdsc->snapid_map_lock)) {
1113 if (!RB_EMPTY_NODE(&sm->node)) {
1114 sm->last_used = jiffies;
1115 list_add_tail(&sm->lru, &mdsc->snapid_map_lru);
1116 spin_unlock(&mdsc->snapid_map_lock);
1117 } else {
1118 /* already cleaned up by
1119 * ceph_cleanup_snapid_map() */
1120 spin_unlock(&mdsc->snapid_map_lock);
1121 kfree(sm);
1122 }
1123 }
1124}
1125
1126void ceph_trim_snapid_map(struct ceph_mds_client *mdsc)
1127{
1128 struct ceph_snapid_map *sm;
1129 unsigned long now;
1130 LIST_HEAD(to_free);
1131
1132 spin_lock(&mdsc->snapid_map_lock);
1133 now = jiffies;
1134
1135 while (!list_empty(&mdsc->snapid_map_lru)) {
1136 sm = list_first_entry(&mdsc->snapid_map_lru,
1137 struct ceph_snapid_map, lru);
1138 if (time_after(sm->last_used + CEPH_SNAPID_MAP_TIMEOUT, now))
1139 break;
1140
1141 rb_erase(&sm->node, &mdsc->snapid_map_tree);
1142 list_move(&sm->lru, &to_free);
1143 }
1144 spin_unlock(&mdsc->snapid_map_lock);
1145
1146 while (!list_empty(&to_free)) {
1147 sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
1148 list_del(&sm->lru);
1149 dout("trim snapid map %llx -> %x\n", sm->snap, sm->dev);
1150 free_anon_bdev(sm->dev);
1151 kfree(sm);
1152 }
1153}
1154
1155void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
1156{
1157 struct ceph_snapid_map *sm;
1158 struct rb_node *p;
1159 LIST_HEAD(to_free);
1160
1161 spin_lock(&mdsc->snapid_map_lock);
1162 while ((p = rb_first(&mdsc->snapid_map_tree))) {
1163 sm = rb_entry(p, struct ceph_snapid_map, node);
1164 rb_erase(p, &mdsc->snapid_map_tree);
1165 RB_CLEAR_NODE(p);
1166 list_move(&sm->lru, &to_free);
1167 }
1168 spin_unlock(&mdsc->snapid_map_lock);
1169
1170 while (!list_empty(&to_free)) {
1171 sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
1172 list_del(&sm->lru);
1173 free_anon_bdev(sm->dev);
1174 if (WARN_ON_ONCE(atomic_read(&sm->ref))) {
1175 pr_err("snapid map %llx -> %x still in use\n",
1176 sm->snap, sm->dev);
1177 }
1178 kfree(sm);
1179 }
1180}