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-rw-r--r--fs/ceph/snap.c911
1 files changed, 911 insertions, 0 deletions
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
new file mode 100644
index 000000000000..d5114db70453
--- /dev/null
+++ b/fs/ceph/snap.c
@@ -0,0 +1,911 @@
1#include "ceph_debug.h"
2
3#include <linux/sort.h>
4#include <linux/slab.h>
5
6#include "super.h"
7#include "decode.h"
8
9/*
10 * Snapshots in ceph are driven in large part by cooperation from the
11 * client. In contrast to local file systems or file servers that
12 * implement snapshots at a single point in the system, ceph's
13 * distributed access to storage requires clients to help decide
14 * whether a write logically occurs before or after a recently created
15 * snapshot.
16 *
17 * This provides a perfect instantanous client-wide snapshot. Between
18 * clients, however, snapshots may appear to be applied at slightly
19 * different points in time, depending on delays in delivering the
20 * snapshot notification.
21 *
22 * Snapshots are _not_ file system-wide. Instead, each snapshot
23 * applies to the subdirectory nested beneath some directory. This
24 * effectively divides the hierarchy into multiple "realms," where all
25 * of the files contained by each realm share the same set of
26 * snapshots. An individual realm's snap set contains snapshots
27 * explicitly created on that realm, as well as any snaps in its
28 * parent's snap set _after_ the point at which the parent became it's
29 * parent (due to, say, a rename). Similarly, snaps from prior parents
30 * during the time intervals during which they were the parent are included.
31 *
32 * The client is spared most of this detail, fortunately... it must only
33 * maintains a hierarchy of realms reflecting the current parent/child
34 * realm relationship, and for each realm has an explicit list of snaps
35 * inherited from prior parents.
36 *
37 * A snap_realm struct is maintained for realms containing every inode
38 * with an open cap in the system. (The needed snap realm information is
39 * provided by the MDS whenever a cap is issued, i.e., on open.) A 'seq'
40 * version number is used to ensure that as realm parameters change (new
41 * snapshot, new parent, etc.) the client's realm hierarchy is updated.
42 *
43 * The realm hierarchy drives the generation of a 'snap context' for each
44 * realm, which simply lists the resulting set of snaps for the realm. This
45 * is attached to any writes sent to OSDs.
46 */
47/*
48 * Unfortunately error handling is a bit mixed here. If we get a snap
49 * update, but don't have enough memory to update our realm hierarchy,
50 * it's not clear what we can do about it (besides complaining to the
51 * console).
52 */
53
54
55/*
56 * increase ref count for the realm
57 *
58 * caller must hold snap_rwsem for write.
59 */
60void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
61 struct ceph_snap_realm *realm)
62{
63 dout("get_realm %p %d -> %d\n", realm,
64 atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
65 /*
66 * since we _only_ increment realm refs or empty the empty
67 * list with snap_rwsem held, adjusting the empty list here is
68 * safe. we do need to protect against concurrent empty list
69 * additions, however.
70 */
71 if (atomic_read(&realm->nref) == 0) {
72 spin_lock(&mdsc->snap_empty_lock);
73 list_del_init(&realm->empty_item);
74 spin_unlock(&mdsc->snap_empty_lock);
75 }
76
77 atomic_inc(&realm->nref);
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, 0); /* tree does not take a ref */
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->inodes_with_caps);
123 spin_lock_init(&realm->inodes_with_caps_lock);
124 __insert_snap_realm(&mdsc->snap_realms, realm);
125 dout("create_snap_realm %llx %p\n", realm->ino, realm);
126 return realm;
127}
128
129/*
130 * lookup the realm rooted at @ino.
131 *
132 * caller must hold snap_rwsem for write.
133 */
134struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
135 u64 ino)
136{
137 struct rb_node *n = mdsc->snap_realms.rb_node;
138 struct ceph_snap_realm *r;
139
140 while (n) {
141 r = rb_entry(n, struct ceph_snap_realm, node);
142 if (ino < r->ino)
143 n = n->rb_left;
144 else if (ino > r->ino)
145 n = n->rb_right;
146 else {
147 dout("lookup_snap_realm %llx %p\n", r->ino, r);
148 return r;
149 }
150 }
151 return NULL;
152}
153
154static void __put_snap_realm(struct ceph_mds_client *mdsc,
155 struct ceph_snap_realm *realm);
156
157/*
158 * called with snap_rwsem (write)
159 */
160static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
161 struct ceph_snap_realm *realm)
162{
163 dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
164
165 rb_erase(&realm->node, &mdsc->snap_realms);
166
167 if (realm->parent) {
168 list_del_init(&realm->child_item);
169 __put_snap_realm(mdsc, realm->parent);
170 }
171
172 kfree(realm->prior_parent_snaps);
173 kfree(realm->snaps);
174 ceph_put_snap_context(realm->cached_context);
175 kfree(realm);
176}
177
178/*
179 * caller holds snap_rwsem (write)
180 */
181static void __put_snap_realm(struct ceph_mds_client *mdsc,
182 struct ceph_snap_realm *realm)
183{
184 dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
185 atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
186 if (atomic_dec_and_test(&realm->nref))
187 __destroy_snap_realm(mdsc, realm);
188}
189
190/*
191 * caller needn't hold any locks
192 */
193void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
194 struct ceph_snap_realm *realm)
195{
196 dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
197 atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
198 if (!atomic_dec_and_test(&realm->nref))
199 return;
200
201 if (down_write_trylock(&mdsc->snap_rwsem)) {
202 __destroy_snap_realm(mdsc, realm);
203 up_write(&mdsc->snap_rwsem);
204 } else {
205 spin_lock(&mdsc->snap_empty_lock);
206 list_add(&mdsc->snap_empty, &realm->empty_item);
207 spin_unlock(&mdsc->snap_empty_lock);
208 }
209}
210
211/*
212 * Clean up any realms whose ref counts have dropped to zero. Note
213 * that this does not include realms who were created but not yet
214 * used.
215 *
216 * Called under snap_rwsem (write)
217 */
218static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
219{
220 struct ceph_snap_realm *realm;
221
222 spin_lock(&mdsc->snap_empty_lock);
223 while (!list_empty(&mdsc->snap_empty)) {
224 realm = list_first_entry(&mdsc->snap_empty,
225 struct ceph_snap_realm, empty_item);
226 list_del(&realm->empty_item);
227 spin_unlock(&mdsc->snap_empty_lock);
228 __destroy_snap_realm(mdsc, realm);
229 spin_lock(&mdsc->snap_empty_lock);
230 }
231 spin_unlock(&mdsc->snap_empty_lock);
232}
233
234void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc)
235{
236 down_write(&mdsc->snap_rwsem);
237 __cleanup_empty_realms(mdsc);
238 up_write(&mdsc->snap_rwsem);
239}
240
241/*
242 * adjust the parent realm of a given @realm. adjust child list, and parent
243 * pointers, and ref counts appropriately.
244 *
245 * return true if parent was changed, 0 if unchanged, <0 on error.
246 *
247 * caller must hold snap_rwsem for write.
248 */
249static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
250 struct ceph_snap_realm *realm,
251 u64 parentino)
252{
253 struct ceph_snap_realm *parent;
254
255 if (realm->parent_ino == parentino)
256 return 0;
257
258 parent = ceph_lookup_snap_realm(mdsc, parentino);
259 if (!parent) {
260 parent = ceph_create_snap_realm(mdsc, parentino);
261 if (IS_ERR(parent))
262 return PTR_ERR(parent);
263 }
264 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
265 realm->ino, realm, realm->parent_ino, realm->parent,
266 parentino, parent);
267 if (realm->parent) {
268 list_del_init(&realm->child_item);
269 ceph_put_snap_realm(mdsc, realm->parent);
270 }
271 realm->parent_ino = parentino;
272 realm->parent = parent;
273 ceph_get_snap_realm(mdsc, parent);
274 list_add(&realm->child_item, &parent->children);
275 return 1;
276}
277
278
279static int cmpu64_rev(const void *a, const void *b)
280{
281 if (*(u64 *)a < *(u64 *)b)
282 return 1;
283 if (*(u64 *)a > *(u64 *)b)
284 return -1;
285 return 0;
286}
287
288/*
289 * build the snap context for a given realm.
290 */
291static int build_snap_context(struct ceph_snap_realm *realm)
292{
293 struct ceph_snap_realm *parent = realm->parent;
294 struct ceph_snap_context *snapc;
295 int err = 0;
296 int i;
297 int num = realm->num_prior_parent_snaps + realm->num_snaps;
298
299 /*
300 * build parent context, if it hasn't been built.
301 * conservatively estimate that all parent snaps might be
302 * included by us.
303 */
304 if (parent) {
305 if (!parent->cached_context) {
306 err = build_snap_context(parent);
307 if (err)
308 goto fail;
309 }
310 num += parent->cached_context->num_snaps;
311 }
312
313 /* do i actually need to update? not if my context seq
314 matches realm seq, and my parents' does to. (this works
315 because we rebuild_snap_realms() works _downward_ in
316 hierarchy after each update.) */
317 if (realm->cached_context &&
318 realm->cached_context->seq == realm->seq &&
319 (!parent ||
320 realm->cached_context->seq >= parent->cached_context->seq)) {
321 dout("build_snap_context %llx %p: %p seq %lld (%d snaps)"
322 " (unchanged)\n",
323 realm->ino, realm, realm->cached_context,
324 realm->cached_context->seq,
325 realm->cached_context->num_snaps);
326 return 0;
327 }
328
329 /* alloc new snap context */
330 err = -ENOMEM;
331 if (num > ULONG_MAX / sizeof(u64) - sizeof(*snapc))
332 goto fail;
333 snapc = kzalloc(sizeof(*snapc) + num*sizeof(u64), GFP_NOFS);
334 if (!snapc)
335 goto fail;
336 atomic_set(&snapc->nref, 1);
337
338 /* build (reverse sorted) snap vector */
339 num = 0;
340 snapc->seq = realm->seq;
341 if (parent) {
342 /* include any of parent's snaps occuring _after_ my
343 parent became my parent */
344 for (i = 0; i < parent->cached_context->num_snaps; i++)
345 if (parent->cached_context->snaps[i] >=
346 realm->parent_since)
347 snapc->snaps[num++] =
348 parent->cached_context->snaps[i];
349 if (parent->cached_context->seq > snapc->seq)
350 snapc->seq = parent->cached_context->seq;
351 }
352 memcpy(snapc->snaps + num, realm->snaps,
353 sizeof(u64)*realm->num_snaps);
354 num += realm->num_snaps;
355 memcpy(snapc->snaps + num, realm->prior_parent_snaps,
356 sizeof(u64)*realm->num_prior_parent_snaps);
357 num += realm->num_prior_parent_snaps;
358
359 sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL);
360 snapc->num_snaps = num;
361 dout("build_snap_context %llx %p: %p seq %lld (%d snaps)\n",
362 realm->ino, realm, snapc, snapc->seq, snapc->num_snaps);
363
364 if (realm->cached_context)
365 ceph_put_snap_context(realm->cached_context);
366 realm->cached_context = snapc;
367 return 0;
368
369fail:
370 /*
371 * if we fail, clear old (incorrect) cached_context... hopefully
372 * we'll have better luck building it later
373 */
374 if (realm->cached_context) {
375 ceph_put_snap_context(realm->cached_context);
376 realm->cached_context = NULL;
377 }
378 pr_err("build_snap_context %llx %p fail %d\n", realm->ino,
379 realm, err);
380 return err;
381}
382
383/*
384 * rebuild snap context for the given realm and all of its children.
385 */
386static void rebuild_snap_realms(struct ceph_snap_realm *realm)
387{
388 struct ceph_snap_realm *child;
389
390 dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
391 build_snap_context(realm);
392
393 list_for_each_entry(child, &realm->children, child_item)
394 rebuild_snap_realms(child);
395}
396
397
398/*
399 * helper to allocate and decode an array of snapids. free prior
400 * instance, if any.
401 */
402static int dup_array(u64 **dst, __le64 *src, int num)
403{
404 int i;
405
406 kfree(*dst);
407 if (num) {
408 *dst = kcalloc(num, sizeof(u64), GFP_NOFS);
409 if (!*dst)
410 return -ENOMEM;
411 for (i = 0; i < num; i++)
412 (*dst)[i] = get_unaligned_le64(src + i);
413 } else {
414 *dst = NULL;
415 }
416 return 0;
417}
418
419
420/*
421 * When a snapshot is applied, the size/mtime inode metadata is queued
422 * in a ceph_cap_snap (one for each snapshot) until writeback
423 * completes and the metadata can be flushed back to the MDS.
424 *
425 * However, if a (sync) write is currently in-progress when we apply
426 * the snapshot, we have to wait until the write succeeds or fails
427 * (and a final size/mtime is known). In this case the
428 * cap_snap->writing = 1, and is said to be "pending." When the write
429 * finishes, we __ceph_finish_cap_snap().
430 *
431 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
432 * change).
433 */
434void ceph_queue_cap_snap(struct ceph_inode_info *ci)
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 already pending\n", inode);
454 kfree(capsnap);
455 } else if (ci->i_wrbuffer_ref_head || (used & CEPH_CAP_FILE_WR)) {
456 struct ceph_snap_context *snapc = ci->i_head_snapc;
457
458 igrab(inode);
459
460 atomic_set(&capsnap->nref, 1);
461 capsnap->ci = ci;
462 INIT_LIST_HEAD(&capsnap->ci_item);
463 INIT_LIST_HEAD(&capsnap->flushing_item);
464
465 capsnap->follows = snapc->seq - 1;
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 capsnap->context = 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 */
511int __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 s=%llu "
525 "still has %d dirty pages\n", inode, capsnap,
526 capsnap->context, capsnap->context->seq,
527 ceph_cap_string(capsnap->dirty), capsnap->size,
528 capsnap->dirty_pages);
529 return 0;
530 }
531 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
532 inode, capsnap, capsnap->context,
533 capsnap->context->seq, ceph_cap_string(capsnap->dirty),
534 capsnap->size);
535
536 spin_lock(&mdsc->snap_flush_lock);
537 list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
538 spin_unlock(&mdsc->snap_flush_lock);
539 return 1; /* caller may want to ceph_flush_snaps */
540}
541
542
543/*
544 * Parse and apply a snapblob "snap trace" from the MDS. This specifies
545 * the snap realm parameters from a given realm and all of its ancestors,
546 * up to the root.
547 *
548 * Caller must hold snap_rwsem for write.
549 */
550int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
551 void *p, void *e, bool deletion)
552{
553 struct ceph_mds_snap_realm *ri; /* encoded */
554 __le64 *snaps; /* encoded */
555 __le64 *prior_parent_snaps; /* encoded */
556 struct ceph_snap_realm *realm;
557 int invalidate = 0;
558 int err = -ENOMEM;
559
560 dout("update_snap_trace deletion=%d\n", deletion);
561more:
562 ceph_decode_need(&p, e, sizeof(*ri), bad);
563 ri = p;
564 p += sizeof(*ri);
565 ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
566 le32_to_cpu(ri->num_prior_parent_snaps)), bad);
567 snaps = p;
568 p += sizeof(u64) * le32_to_cpu(ri->num_snaps);
569 prior_parent_snaps = p;
570 p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps);
571
572 realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
573 if (!realm) {
574 realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
575 if (IS_ERR(realm)) {
576 err = PTR_ERR(realm);
577 goto fail;
578 }
579 }
580
581 if (le64_to_cpu(ri->seq) > realm->seq) {
582 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
583 realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
584 /*
585 * if the realm seq has changed, queue a cap_snap for every
586 * inode with open caps. we do this _before_ we update
587 * the realm info so that we prepare for writeback under the
588 * _previous_ snap context.
589 *
590 * ...unless it's a snap deletion!
591 */
592 if (!deletion) {
593 struct ceph_inode_info *ci;
594 struct inode *lastinode = NULL;
595
596 spin_lock(&realm->inodes_with_caps_lock);
597 list_for_each_entry(ci, &realm->inodes_with_caps,
598 i_snap_realm_item) {
599 struct inode *inode = igrab(&ci->vfs_inode);
600 if (!inode)
601 continue;
602 spin_unlock(&realm->inodes_with_caps_lock);
603 if (lastinode)
604 iput(lastinode);
605 lastinode = inode;
606 ceph_queue_cap_snap(ci);
607 spin_lock(&realm->inodes_with_caps_lock);
608 }
609 spin_unlock(&realm->inodes_with_caps_lock);
610 if (lastinode)
611 iput(lastinode);
612 dout("update_snap_trace cap_snaps queued\n");
613 }
614
615 } else {
616 dout("update_snap_trace %llx %p seq %lld unchanged\n",
617 realm->ino, realm, realm->seq);
618 }
619
620 /* ensure the parent is correct */
621 err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
622 if (err < 0)
623 goto fail;
624 invalidate += err;
625
626 if (le64_to_cpu(ri->seq) > realm->seq) {
627 /* update realm parameters, snap lists */
628 realm->seq = le64_to_cpu(ri->seq);
629 realm->created = le64_to_cpu(ri->created);
630 realm->parent_since = le64_to_cpu(ri->parent_since);
631
632 realm->num_snaps = le32_to_cpu(ri->num_snaps);
633 err = dup_array(&realm->snaps, snaps, realm->num_snaps);
634 if (err < 0)
635 goto fail;
636
637 realm->num_prior_parent_snaps =
638 le32_to_cpu(ri->num_prior_parent_snaps);
639 err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps,
640 realm->num_prior_parent_snaps);
641 if (err < 0)
642 goto fail;
643
644 invalidate = 1;
645 } else if (!realm->cached_context) {
646 invalidate = 1;
647 }
648
649 dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
650 realm, invalidate, p, e);
651
652 if (p < e)
653 goto more;
654
655 /* invalidate when we reach the _end_ (root) of the trace */
656 if (invalidate)
657 rebuild_snap_realms(realm);
658
659 __cleanup_empty_realms(mdsc);
660 return 0;
661
662bad:
663 err = -EINVAL;
664fail:
665 pr_err("update_snap_trace error %d\n", err);
666 return err;
667}
668
669
670/*
671 * Send any cap_snaps that are queued for flush. Try to carry
672 * s_mutex across multiple snap flushes to avoid locking overhead.
673 *
674 * Caller holds no locks.
675 */
676static void flush_snaps(struct ceph_mds_client *mdsc)
677{
678 struct ceph_inode_info *ci;
679 struct inode *inode;
680 struct ceph_mds_session *session = NULL;
681
682 dout("flush_snaps\n");
683 spin_lock(&mdsc->snap_flush_lock);
684 while (!list_empty(&mdsc->snap_flush_list)) {
685 ci = list_first_entry(&mdsc->snap_flush_list,
686 struct ceph_inode_info, i_snap_flush_item);
687 inode = &ci->vfs_inode;
688 igrab(inode);
689 spin_unlock(&mdsc->snap_flush_lock);
690 spin_lock(&inode->i_lock);
691 __ceph_flush_snaps(ci, &session);
692 spin_unlock(&inode->i_lock);
693 iput(inode);
694 spin_lock(&mdsc->snap_flush_lock);
695 }
696 spin_unlock(&mdsc->snap_flush_lock);
697
698 if (session) {
699 mutex_unlock(&session->s_mutex);
700 ceph_put_mds_session(session);
701 }
702 dout("flush_snaps done\n");
703}
704
705
706/*
707 * Handle a snap notification from the MDS.
708 *
709 * This can take two basic forms: the simplest is just a snap creation
710 * or deletion notification on an existing realm. This should update the
711 * realm and its children.
712 *
713 * The more difficult case is realm creation, due to snap creation at a
714 * new point in the file hierarchy, or due to a rename that moves a file or
715 * directory into another realm.
716 */
717void ceph_handle_snap(struct ceph_mds_client *mdsc,
718 struct ceph_mds_session *session,
719 struct ceph_msg *msg)
720{
721 struct super_block *sb = mdsc->client->sb;
722 int mds = session->s_mds;
723 u64 split;
724 int op;
725 int trace_len;
726 struct ceph_snap_realm *realm = NULL;
727 void *p = msg->front.iov_base;
728 void *e = p + msg->front.iov_len;
729 struct ceph_mds_snap_head *h;
730 int num_split_inos, num_split_realms;
731 __le64 *split_inos = NULL, *split_realms = NULL;
732 int i;
733 int locked_rwsem = 0;
734
735 /* decode */
736 if (msg->front.iov_len < sizeof(*h))
737 goto bad;
738 h = p;
739 op = le32_to_cpu(h->op);
740 split = le64_to_cpu(h->split); /* non-zero if we are splitting an
741 * existing realm */
742 num_split_inos = le32_to_cpu(h->num_split_inos);
743 num_split_realms = le32_to_cpu(h->num_split_realms);
744 trace_len = le32_to_cpu(h->trace_len);
745 p += sizeof(*h);
746
747 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds,
748 ceph_snap_op_name(op), split, trace_len);
749
750 mutex_lock(&session->s_mutex);
751 session->s_seq++;
752 mutex_unlock(&session->s_mutex);
753
754 down_write(&mdsc->snap_rwsem);
755 locked_rwsem = 1;
756
757 if (op == CEPH_SNAP_OP_SPLIT) {
758 struct ceph_mds_snap_realm *ri;
759
760 /*
761 * A "split" breaks part of an existing realm off into
762 * a new realm. The MDS provides a list of inodes
763 * (with caps) and child realms that belong to the new
764 * child.
765 */
766 split_inos = p;
767 p += sizeof(u64) * num_split_inos;
768 split_realms = p;
769 p += sizeof(u64) * num_split_realms;
770 ceph_decode_need(&p, e, sizeof(*ri), bad);
771 /* we will peek at realm info here, but will _not_
772 * advance p, as the realm update will occur below in
773 * ceph_update_snap_trace. */
774 ri = p;
775
776 realm = ceph_lookup_snap_realm(mdsc, split);
777 if (!realm) {
778 realm = ceph_create_snap_realm(mdsc, split);
779 if (IS_ERR(realm))
780 goto out;
781 }
782 ceph_get_snap_realm(mdsc, realm);
783
784 dout("splitting snap_realm %llx %p\n", realm->ino, realm);
785 for (i = 0; i < num_split_inos; i++) {
786 struct ceph_vino vino = {
787 .ino = le64_to_cpu(split_inos[i]),
788 .snap = CEPH_NOSNAP,
789 };
790 struct inode *inode = ceph_find_inode(sb, vino);
791 struct ceph_inode_info *ci;
792
793 if (!inode)
794 continue;
795 ci = ceph_inode(inode);
796
797 spin_lock(&inode->i_lock);
798 if (!ci->i_snap_realm)
799 goto skip_inode;
800 /*
801 * If this inode belongs to a realm that was
802 * created after our new realm, we experienced
803 * a race (due to another split notifications
804 * arriving from a different MDS). So skip
805 * this inode.
806 */
807 if (ci->i_snap_realm->created >
808 le64_to_cpu(ri->created)) {
809 dout(" leaving %p in newer realm %llx %p\n",
810 inode, ci->i_snap_realm->ino,
811 ci->i_snap_realm);
812 goto skip_inode;
813 }
814 dout(" will move %p to split realm %llx %p\n",
815 inode, realm->ino, realm);
816 /*
817 * Remove the inode from the realm's inode
818 * list, but don't add it to the new realm
819 * yet. We don't want the cap_snap to be
820 * queued (again) by ceph_update_snap_trace()
821 * below. Queue it _now_, under the old context.
822 */
823 spin_lock(&realm->inodes_with_caps_lock);
824 list_del_init(&ci->i_snap_realm_item);
825 spin_unlock(&realm->inodes_with_caps_lock);
826 spin_unlock(&inode->i_lock);
827
828 ceph_queue_cap_snap(ci);
829
830 iput(inode);
831 continue;
832
833skip_inode:
834 spin_unlock(&inode->i_lock);
835 iput(inode);
836 }
837
838 /* we may have taken some of the old realm's children. */
839 for (i = 0; i < num_split_realms; i++) {
840 struct ceph_snap_realm *child =
841 ceph_lookup_snap_realm(mdsc,
842 le64_to_cpu(split_realms[i]));
843 if (!child)
844 continue;
845 adjust_snap_realm_parent(mdsc, child, realm->ino);
846 }
847 }
848
849 /*
850 * update using the provided snap trace. if we are deleting a
851 * snap, we can avoid queueing cap_snaps.
852 */
853 ceph_update_snap_trace(mdsc, p, e,
854 op == CEPH_SNAP_OP_DESTROY);
855
856 if (op == CEPH_SNAP_OP_SPLIT) {
857 /*
858 * ok, _now_ add the inodes into the new realm.
859 */
860 for (i = 0; i < num_split_inos; i++) {
861 struct ceph_vino vino = {
862 .ino = le64_to_cpu(split_inos[i]),
863 .snap = CEPH_NOSNAP,
864 };
865 struct inode *inode = ceph_find_inode(sb, vino);
866 struct ceph_inode_info *ci;
867
868 if (!inode)
869 continue;
870 ci = ceph_inode(inode);
871 spin_lock(&inode->i_lock);
872 if (list_empty(&ci->i_snap_realm_item)) {
873 struct ceph_snap_realm *oldrealm =
874 ci->i_snap_realm;
875
876 dout(" moving %p to split realm %llx %p\n",
877 inode, realm->ino, realm);
878 spin_lock(&realm->inodes_with_caps_lock);
879 list_add(&ci->i_snap_realm_item,
880 &realm->inodes_with_caps);
881 ci->i_snap_realm = realm;
882 spin_unlock(&realm->inodes_with_caps_lock);
883 ceph_get_snap_realm(mdsc, realm);
884 ceph_put_snap_realm(mdsc, oldrealm);
885 }
886 spin_unlock(&inode->i_lock);
887 iput(inode);
888 }
889
890 /* we took a reference when we created the realm, above */
891 ceph_put_snap_realm(mdsc, realm);
892 }
893
894 __cleanup_empty_realms(mdsc);
895
896 up_write(&mdsc->snap_rwsem);
897
898 flush_snaps(mdsc);
899 return;
900
901bad:
902 pr_err("corrupt snap message from mds%d\n", mds);
903 ceph_msg_dump(msg);
904out:
905 if (locked_rwsem)
906 up_write(&mdsc->snap_rwsem);
907 return;
908}
909
910
911
generated by cgit v1.2.2 (git 2.25.0) at 2025-01-13 02:56:15 -0500