1 #include <linux/ceph/ceph_debug.h>
3 #include <linux/sort.h>
4 #include <linux/slab.h>
7 #include "mds_client.h"
9 #include <linux/ceph/decode.h>
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
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.
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.
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.
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.
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.
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
58 * increase ref count for the realm
60 * caller must hold snap_rwsem for write.
62 void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
63 struct ceph_snap_realm *realm)
65 dout("get_realm %p %d -> %d\n", realm,
66 atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
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
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);
80 static void __insert_snap_realm(struct rb_root *root,
81 struct ceph_snap_realm *new)
83 struct rb_node **p = &root->rb_node;
84 struct rb_node *parent = NULL;
85 struct ceph_snap_realm *r = NULL;
89 r = rb_entry(parent, struct ceph_snap_realm, node);
90 if (new->ino < r->ino)
92 else if (new->ino > r->ino)
98 rb_link_node(&new->node, parent, p);
99 rb_insert_color(&new->node, root);
103 * create and get the realm rooted at @ino and bump its ref count.
105 * caller must hold snap_rwsem for write.
107 static struct ceph_snap_realm *ceph_create_snap_realm(
108 struct ceph_mds_client *mdsc,
111 struct ceph_snap_realm *realm;
113 realm = kzalloc(sizeof(*realm), GFP_NOFS);
115 return ERR_PTR(-ENOMEM);
117 atomic_set(&realm->nref, 1); /* for caller */
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);
131 * lookup the realm rooted at @ino.
133 * caller must hold snap_rwsem for write.
135 static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
138 struct rb_node *n = mdsc->snap_realms.rb_node;
139 struct ceph_snap_realm *r;
142 r = rb_entry(n, struct ceph_snap_realm, node);
145 else if (ino > r->ino)
148 dout("lookup_snap_realm %llx %p\n", r->ino, r);
155 struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
158 struct ceph_snap_realm *r;
159 r = __lookup_snap_realm(mdsc, ino);
161 ceph_get_snap_realm(mdsc, r);
165 static void __put_snap_realm(struct ceph_mds_client *mdsc,
166 struct ceph_snap_realm *realm);
169 * called with snap_rwsem (write)
171 static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
172 struct ceph_snap_realm *realm)
174 dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
176 rb_erase(&realm->node, &mdsc->snap_realms);
179 list_del_init(&realm->child_item);
180 __put_snap_realm(mdsc, realm->parent);
183 kfree(realm->prior_parent_snaps);
185 ceph_put_snap_context(realm->cached_context);
190 * caller holds snap_rwsem (write)
192 static void __put_snap_realm(struct ceph_mds_client *mdsc,
193 struct ceph_snap_realm *realm)
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);
202 * caller needn't hold any locks
204 void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
205 struct ceph_snap_realm *realm)
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))
212 if (down_write_trylock(&mdsc->snap_rwsem)) {
213 __destroy_snap_realm(mdsc, realm);
214 up_write(&mdsc->snap_rwsem);
216 spin_lock(&mdsc->snap_empty_lock);
217 list_add(&realm->empty_item, &mdsc->snap_empty);
218 spin_unlock(&mdsc->snap_empty_lock);
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
227 * Called under snap_rwsem (write)
229 static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
231 struct ceph_snap_realm *realm;
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);
242 spin_unlock(&mdsc->snap_empty_lock);
245 void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc)
247 down_write(&mdsc->snap_rwsem);
248 __cleanup_empty_realms(mdsc);
249 up_write(&mdsc->snap_rwsem);
253 * adjust the parent realm of a given @realm. adjust child list, and parent
254 * pointers, and ref counts appropriately.
256 * return true if parent was changed, 0 if unchanged, <0 on error.
258 * caller must hold snap_rwsem for write.
260 static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
261 struct ceph_snap_realm *realm,
264 struct ceph_snap_realm *parent;
266 if (realm->parent_ino == parentino)
269 parent = ceph_lookup_snap_realm(mdsc, parentino);
271 parent = ceph_create_snap_realm(mdsc, parentino);
273 return PTR_ERR(parent);
275 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
276 realm->ino, realm, realm->parent_ino, realm->parent,
279 list_del_init(&realm->child_item);
280 ceph_put_snap_realm(mdsc, realm->parent);
282 realm->parent_ino = parentino;
283 realm->parent = parent;
284 list_add(&realm->child_item, &parent->children);
289 static int cmpu64_rev(const void *a, const void *b)
291 if (*(u64 *)a < *(u64 *)b)
293 if (*(u64 *)a > *(u64 *)b)
300 * build the snap context for a given realm.
302 static int build_snap_context(struct ceph_snap_realm *realm)
304 struct ceph_snap_realm *parent = realm->parent;
305 struct ceph_snap_context *snapc;
307 u32 num = realm->num_prior_parent_snaps + realm->num_snaps;
310 * build parent context, if it hasn't been built.
311 * conservatively estimate that all parent snaps might be
315 if (!parent->cached_context) {
316 err = build_snap_context(parent);
320 num += parent->cached_context->num_snaps;
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 &&
330 realm->cached_context->seq >= parent->cached_context->seq)) {
331 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)"
333 realm->ino, realm, realm->cached_context,
334 realm->cached_context->seq,
335 (unsigned int) realm->cached_context->num_snaps);
339 /* alloc new snap context */
341 if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
343 snapc = ceph_create_snap_context(num, GFP_NOFS);
347 /* build (reverse sorted) snap vector */
349 snapc->seq = realm->seq;
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] >=
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;
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;
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);
376 ceph_put_snap_context(realm->cached_context);
377 realm->cached_context = snapc;
382 * if we fail, clear old (incorrect) cached_context... hopefully
383 * we'll have better luck building it later
385 if (realm->cached_context) {
386 ceph_put_snap_context(realm->cached_context);
387 realm->cached_context = NULL;
389 pr_err("build_snap_context %llx %p fail %d\n", realm->ino,
395 * rebuild snap context for the given realm and all of its children.
397 static void rebuild_snap_realms(struct ceph_snap_realm *realm)
399 struct ceph_snap_realm *child;
401 dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
402 build_snap_context(realm);
404 list_for_each_entry(child, &realm->children, child_item)
405 rebuild_snap_realms(child);
410 * helper to allocate and decode an array of snapids. free prior
413 static int dup_array(u64 **dst, __le64 *src, u32 num)
419 *dst = kcalloc(num, sizeof(u64), GFP_NOFS);
422 for (i = 0; i < num; i++)
423 (*dst)[i] = get_unaligned_le64(src + i);
430 static bool has_new_snaps(struct ceph_snap_context *o,
431 struct ceph_snap_context *n)
433 if (n->num_snaps == 0)
435 /* snaps are in descending order */
436 return n->snaps[0] > o->seq;
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.
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().
450 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
453 void ceph_queue_cap_snap(struct ceph_inode_info *ci)
455 struct inode *inode = &ci->vfs_inode;
456 struct ceph_cap_snap *capsnap;
457 struct ceph_snap_context *old_snapc, *new_snapc;
460 capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
462 pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
466 spin_lock(&ci->i_ceph_lock);
467 used = __ceph_caps_used(ci);
468 dirty = __ceph_caps_dirty(ci);
470 old_snapc = ci->i_head_snapc;
471 new_snapc = ci->i_snap_realm->cached_context;
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.
478 if (used & CEPH_CAP_FILE_WR)
479 dirty |= CEPH_CAP_FILE_WR;
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);
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);
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.
503 * also see ceph_try_drop_cap_snap()
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;
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);
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");
522 atomic_set(&capsnap->nref, 1);
523 INIT_LIST_HEAD(&capsnap->ci_item);
525 capsnap->follows = old_snapc->seq;
526 capsnap->issued = __ceph_caps_issued(ci, NULL);
527 capsnap->dirty = dirty;
529 capsnap->mode = inode->i_mode;
530 capsnap->uid = inode->i_uid;
531 capsnap->gid = inode->i_gid;
533 if (dirty & CEPH_CAP_XATTR_EXCL) {
534 __ceph_build_xattrs_blob(ci);
535 capsnap->xattr_blob =
536 ceph_buffer_get(ci->i_xattrs.blob);
537 capsnap->xattr_version = ci->i_xattrs.version;
539 capsnap->xattr_blob = NULL;
540 capsnap->xattr_version = 0;
543 capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
545 /* dirty page count moved from _head to this cap_snap;
546 all subsequent writes page dirties occur _after_ this
548 capsnap->dirty_pages = ci->i_wrbuffer_ref_head;
549 ci->i_wrbuffer_ref_head = 0;
550 capsnap->context = old_snapc;
551 list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);
553 if (used & CEPH_CAP_FILE_WR) {
554 dout("queue_cap_snap %p cap_snap %p snapc %p"
555 " seq %llu used WR, now pending\n", inode,
556 capsnap, old_snapc, old_snapc->seq);
557 capsnap->writing = 1;
559 /* note mtime, size NOW. */
560 __ceph_finish_cap_snap(ci, capsnap);
566 if (ci->i_wrbuffer_ref_head == 0 &&
568 ci->i_dirty_caps == 0 &&
569 ci->i_flushing_caps == 0) {
570 ci->i_head_snapc = NULL;
572 ci->i_head_snapc = ceph_get_snap_context(new_snapc);
573 dout(" new snapc is %p\n", new_snapc);
575 spin_unlock(&ci->i_ceph_lock);
578 ceph_put_snap_context(old_snapc);
582 * Finalize the size, mtime for a cap_snap.. that is, settle on final values
583 * to be used for the snapshot, to be flushed back to the mds.
585 * If capsnap can now be flushed, add to snap_flush list, and return 1.
587 * Caller must hold i_ceph_lock.
589 int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
590 struct ceph_cap_snap *capsnap)
592 struct inode *inode = &ci->vfs_inode;
593 struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
595 BUG_ON(capsnap->writing);
596 capsnap->size = inode->i_size;
597 capsnap->mtime = inode->i_mtime;
598 capsnap->atime = inode->i_atime;
599 capsnap->ctime = inode->i_ctime;
600 capsnap->time_warp_seq = ci->i_time_warp_seq;
601 if (capsnap->dirty_pages) {
602 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
603 "still has %d dirty pages\n", inode, capsnap,
604 capsnap->context, capsnap->context->seq,
605 ceph_cap_string(capsnap->dirty), capsnap->size,
606 capsnap->dirty_pages);
610 ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
611 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
612 inode, capsnap, capsnap->context,
613 capsnap->context->seq, ceph_cap_string(capsnap->dirty),
616 spin_lock(&mdsc->snap_flush_lock);
617 if (list_empty(&ci->i_snap_flush_item))
618 list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
619 spin_unlock(&mdsc->snap_flush_lock);
620 return 1; /* caller may want to ceph_flush_snaps */
624 * Queue cap_snaps for snap writeback for this realm and its children.
625 * Called under snap_rwsem, so realm topology won't change.
627 static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
629 struct ceph_inode_info *ci;
630 struct inode *lastinode = NULL;
631 struct ceph_snap_realm *child;
633 dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
635 spin_lock(&realm->inodes_with_caps_lock);
636 list_for_each_entry(ci, &realm->inodes_with_caps,
638 struct inode *inode = igrab(&ci->vfs_inode);
641 spin_unlock(&realm->inodes_with_caps_lock);
644 ceph_queue_cap_snap(ci);
645 spin_lock(&realm->inodes_with_caps_lock);
647 spin_unlock(&realm->inodes_with_caps_lock);
650 list_for_each_entry(child, &realm->children, child_item) {
651 dout("queue_realm_cap_snaps %p %llx queue child %p %llx\n",
652 realm, realm->ino, child, child->ino);
653 list_del_init(&child->dirty_item);
654 list_add(&child->dirty_item, &realm->dirty_item);
657 list_del_init(&realm->dirty_item);
658 dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
662 * Parse and apply a snapblob "snap trace" from the MDS. This specifies
663 * the snap realm parameters from a given realm and all of its ancestors,
666 * Caller must hold snap_rwsem for write.
668 int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
669 void *p, void *e, bool deletion,
670 struct ceph_snap_realm **realm_ret)
672 struct ceph_mds_snap_realm *ri; /* encoded */
673 __le64 *snaps; /* encoded */
674 __le64 *prior_parent_snaps; /* encoded */
675 struct ceph_snap_realm *realm = NULL;
676 struct ceph_snap_realm *first_realm = NULL;
679 LIST_HEAD(dirty_realms);
681 dout("update_snap_trace deletion=%d\n", deletion);
683 ceph_decode_need(&p, e, sizeof(*ri), bad);
686 ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
687 le32_to_cpu(ri->num_prior_parent_snaps)), bad);
689 p += sizeof(u64) * le32_to_cpu(ri->num_snaps);
690 prior_parent_snaps = p;
691 p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps);
693 realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
695 realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
697 err = PTR_ERR(realm);
702 /* ensure the parent is correct */
703 err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
708 if (le64_to_cpu(ri->seq) > realm->seq) {
709 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
710 realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
711 /* update realm parameters, snap lists */
712 realm->seq = le64_to_cpu(ri->seq);
713 realm->created = le64_to_cpu(ri->created);
714 realm->parent_since = le64_to_cpu(ri->parent_since);
716 realm->num_snaps = le32_to_cpu(ri->num_snaps);
717 err = dup_array(&realm->snaps, snaps, realm->num_snaps);
721 realm->num_prior_parent_snaps =
722 le32_to_cpu(ri->num_prior_parent_snaps);
723 err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps,
724 realm->num_prior_parent_snaps);
728 /* queue realm for cap_snap creation */
729 list_add(&realm->dirty_item, &dirty_realms);
730 if (realm->seq > mdsc->last_snap_seq)
731 mdsc->last_snap_seq = realm->seq;
734 } else if (!realm->cached_context) {
735 dout("update_snap_trace %llx %p seq %lld new\n",
736 realm->ino, realm, realm->seq);
739 dout("update_snap_trace %llx %p seq %lld unchanged\n",
740 realm->ino, realm, realm->seq);
743 dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
744 realm, invalidate, p, e);
746 /* invalidate when we reach the _end_ (root) of the trace */
747 if (invalidate && p >= e)
748 rebuild_snap_realms(realm);
753 ceph_put_snap_realm(mdsc, realm);
759 * queue cap snaps _after_ we've built the new snap contexts,
760 * so that i_head_snapc can be set appropriately.
762 while (!list_empty(&dirty_realms)) {
763 realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
765 queue_realm_cap_snaps(realm);
769 *realm_ret = first_realm;
771 ceph_put_snap_realm(mdsc, first_realm);
773 __cleanup_empty_realms(mdsc);
779 if (realm && !IS_ERR(realm))
780 ceph_put_snap_realm(mdsc, realm);
782 ceph_put_snap_realm(mdsc, first_realm);
783 pr_err("update_snap_trace error %d\n", err);
789 * Send any cap_snaps that are queued for flush. Try to carry
790 * s_mutex across multiple snap flushes to avoid locking overhead.
792 * Caller holds no locks.
794 static void flush_snaps(struct ceph_mds_client *mdsc)
796 struct ceph_inode_info *ci;
798 struct ceph_mds_session *session = NULL;
800 dout("flush_snaps\n");
801 spin_lock(&mdsc->snap_flush_lock);
802 while (!list_empty(&mdsc->snap_flush_list)) {
803 ci = list_first_entry(&mdsc->snap_flush_list,
804 struct ceph_inode_info, i_snap_flush_item);
805 inode = &ci->vfs_inode;
807 spin_unlock(&mdsc->snap_flush_lock);
808 ceph_flush_snaps(ci, &session);
810 spin_lock(&mdsc->snap_flush_lock);
812 spin_unlock(&mdsc->snap_flush_lock);
815 mutex_unlock(&session->s_mutex);
816 ceph_put_mds_session(session);
818 dout("flush_snaps done\n");
823 * Handle a snap notification from the MDS.
825 * This can take two basic forms: the simplest is just a snap creation
826 * or deletion notification on an existing realm. This should update the
827 * realm and its children.
829 * The more difficult case is realm creation, due to snap creation at a
830 * new point in the file hierarchy, or due to a rename that moves a file or
831 * directory into another realm.
833 void ceph_handle_snap(struct ceph_mds_client *mdsc,
834 struct ceph_mds_session *session,
835 struct ceph_msg *msg)
837 struct super_block *sb = mdsc->fsc->sb;
838 int mds = session->s_mds;
842 struct ceph_snap_realm *realm = NULL;
843 void *p = msg->front.iov_base;
844 void *e = p + msg->front.iov_len;
845 struct ceph_mds_snap_head *h;
846 int num_split_inos, num_split_realms;
847 __le64 *split_inos = NULL, *split_realms = NULL;
849 int locked_rwsem = 0;
852 if (msg->front.iov_len < sizeof(*h))
855 op = le32_to_cpu(h->op);
856 split = le64_to_cpu(h->split); /* non-zero if we are splitting an
858 num_split_inos = le32_to_cpu(h->num_split_inos);
859 num_split_realms = le32_to_cpu(h->num_split_realms);
860 trace_len = le32_to_cpu(h->trace_len);
863 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds,
864 ceph_snap_op_name(op), split, trace_len);
866 mutex_lock(&session->s_mutex);
868 mutex_unlock(&session->s_mutex);
870 down_write(&mdsc->snap_rwsem);
873 if (op == CEPH_SNAP_OP_SPLIT) {
874 struct ceph_mds_snap_realm *ri;
877 * A "split" breaks part of an existing realm off into
878 * a new realm. The MDS provides a list of inodes
879 * (with caps) and child realms that belong to the new
883 p += sizeof(u64) * num_split_inos;
885 p += sizeof(u64) * num_split_realms;
886 ceph_decode_need(&p, e, sizeof(*ri), bad);
887 /* we will peek at realm info here, but will _not_
888 * advance p, as the realm update will occur below in
889 * ceph_update_snap_trace. */
892 realm = ceph_lookup_snap_realm(mdsc, split);
894 realm = ceph_create_snap_realm(mdsc, split);
899 dout("splitting snap_realm %llx %p\n", realm->ino, realm);
900 for (i = 0; i < num_split_inos; i++) {
901 struct ceph_vino vino = {
902 .ino = le64_to_cpu(split_inos[i]),
905 struct inode *inode = ceph_find_inode(sb, vino);
906 struct ceph_inode_info *ci;
907 struct ceph_snap_realm *oldrealm;
911 ci = ceph_inode(inode);
913 spin_lock(&ci->i_ceph_lock);
914 if (!ci->i_snap_realm)
917 * If this inode belongs to a realm that was
918 * created after our new realm, we experienced
919 * a race (due to another split notifications
920 * arriving from a different MDS). So skip
923 if (ci->i_snap_realm->created >
924 le64_to_cpu(ri->created)) {
925 dout(" leaving %p in newer realm %llx %p\n",
926 inode, ci->i_snap_realm->ino,
930 dout(" will move %p to split realm %llx %p\n",
931 inode, realm->ino, realm);
933 * Move the inode to the new realm
935 spin_lock(&realm->inodes_with_caps_lock);
936 list_del_init(&ci->i_snap_realm_item);
937 list_add(&ci->i_snap_realm_item,
938 &realm->inodes_with_caps);
939 oldrealm = ci->i_snap_realm;
940 ci->i_snap_realm = realm;
941 spin_unlock(&realm->inodes_with_caps_lock);
942 spin_unlock(&ci->i_ceph_lock);
944 ceph_get_snap_realm(mdsc, realm);
945 ceph_put_snap_realm(mdsc, oldrealm);
951 spin_unlock(&ci->i_ceph_lock);
955 /* we may have taken some of the old realm's children. */
956 for (i = 0; i < num_split_realms; i++) {
957 struct ceph_snap_realm *child =
958 __lookup_snap_realm(mdsc,
959 le64_to_cpu(split_realms[i]));
962 adjust_snap_realm_parent(mdsc, child, realm->ino);
967 * update using the provided snap trace. if we are deleting a
968 * snap, we can avoid queueing cap_snaps.
970 ceph_update_snap_trace(mdsc, p, e,
971 op == CEPH_SNAP_OP_DESTROY, NULL);
973 if (op == CEPH_SNAP_OP_SPLIT)
974 /* we took a reference when we created the realm, above */
975 ceph_put_snap_realm(mdsc, realm);
977 __cleanup_empty_realms(mdsc);
979 up_write(&mdsc->snap_rwsem);
985 pr_err("corrupt snap message from mds%d\n", mds);
989 up_write(&mdsc->snap_rwsem);