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_read(&realm
->nref
) == 0) {
74 spin_lock(&mdsc
->snap_empty_lock
);
75 list_del_init(&realm
->empty_item
);
76 spin_unlock(&mdsc
->snap_empty_lock
);
79 atomic_inc(&realm
->nref
);
82 static void __insert_snap_realm(struct rb_root
*root
,
83 struct ceph_snap_realm
*new)
85 struct rb_node
**p
= &root
->rb_node
;
86 struct rb_node
*parent
= NULL
;
87 struct ceph_snap_realm
*r
= NULL
;
91 r
= rb_entry(parent
, struct ceph_snap_realm
, node
);
92 if (new->ino
< r
->ino
)
94 else if (new->ino
> r
->ino
)
100 rb_link_node(&new->node
, parent
, p
);
101 rb_insert_color(&new->node
, root
);
105 * create and get the realm rooted at @ino and bump its ref count.
107 * caller must hold snap_rwsem for write.
109 static struct ceph_snap_realm
*ceph_create_snap_realm(
110 struct ceph_mds_client
*mdsc
,
113 struct ceph_snap_realm
*realm
;
115 realm
= kzalloc(sizeof(*realm
), GFP_NOFS
);
117 return ERR_PTR(-ENOMEM
);
119 atomic_set(&realm
->nref
, 0); /* tree does not take a ref */
121 INIT_LIST_HEAD(&realm
->children
);
122 INIT_LIST_HEAD(&realm
->child_item
);
123 INIT_LIST_HEAD(&realm
->empty_item
);
124 INIT_LIST_HEAD(&realm
->dirty_item
);
125 INIT_LIST_HEAD(&realm
->inodes_with_caps
);
126 spin_lock_init(&realm
->inodes_with_caps_lock
);
127 __insert_snap_realm(&mdsc
->snap_realms
, realm
);
128 dout("create_snap_realm %llx %p\n", realm
->ino
, realm
);
133 * lookup the realm rooted at @ino.
135 * caller must hold snap_rwsem for write.
137 struct ceph_snap_realm
*ceph_lookup_snap_realm(struct ceph_mds_client
*mdsc
,
140 struct rb_node
*n
= mdsc
->snap_realms
.rb_node
;
141 struct ceph_snap_realm
*r
;
144 r
= rb_entry(n
, struct ceph_snap_realm
, node
);
147 else if (ino
> r
->ino
)
150 dout("lookup_snap_realm %llx %p\n", r
->ino
, r
);
157 static void __put_snap_realm(struct ceph_mds_client
*mdsc
,
158 struct ceph_snap_realm
*realm
);
161 * called with snap_rwsem (write)
163 static void __destroy_snap_realm(struct ceph_mds_client
*mdsc
,
164 struct ceph_snap_realm
*realm
)
166 dout("__destroy_snap_realm %p %llx\n", realm
, realm
->ino
);
168 rb_erase(&realm
->node
, &mdsc
->snap_realms
);
171 list_del_init(&realm
->child_item
);
172 __put_snap_realm(mdsc
, realm
->parent
);
175 kfree(realm
->prior_parent_snaps
);
177 ceph_put_snap_context(realm
->cached_context
);
182 * caller holds snap_rwsem (write)
184 static void __put_snap_realm(struct ceph_mds_client
*mdsc
,
185 struct ceph_snap_realm
*realm
)
187 dout("__put_snap_realm %llx %p %d -> %d\n", realm
->ino
, realm
,
188 atomic_read(&realm
->nref
), atomic_read(&realm
->nref
)-1);
189 if (atomic_dec_and_test(&realm
->nref
))
190 __destroy_snap_realm(mdsc
, realm
);
194 * caller needn't hold any locks
196 void ceph_put_snap_realm(struct ceph_mds_client
*mdsc
,
197 struct ceph_snap_realm
*realm
)
199 dout("put_snap_realm %llx %p %d -> %d\n", realm
->ino
, realm
,
200 atomic_read(&realm
->nref
), atomic_read(&realm
->nref
)-1);
201 if (!atomic_dec_and_test(&realm
->nref
))
204 if (down_write_trylock(&mdsc
->snap_rwsem
)) {
205 __destroy_snap_realm(mdsc
, realm
);
206 up_write(&mdsc
->snap_rwsem
);
208 spin_lock(&mdsc
->snap_empty_lock
);
209 list_add(&realm
->empty_item
, &mdsc
->snap_empty
);
210 spin_unlock(&mdsc
->snap_empty_lock
);
215 * Clean up any realms whose ref counts have dropped to zero. Note
216 * that this does not include realms who were created but not yet
219 * Called under snap_rwsem (write)
221 static void __cleanup_empty_realms(struct ceph_mds_client
*mdsc
)
223 struct ceph_snap_realm
*realm
;
225 spin_lock(&mdsc
->snap_empty_lock
);
226 while (!list_empty(&mdsc
->snap_empty
)) {
227 realm
= list_first_entry(&mdsc
->snap_empty
,
228 struct ceph_snap_realm
, empty_item
);
229 list_del(&realm
->empty_item
);
230 spin_unlock(&mdsc
->snap_empty_lock
);
231 __destroy_snap_realm(mdsc
, realm
);
232 spin_lock(&mdsc
->snap_empty_lock
);
234 spin_unlock(&mdsc
->snap_empty_lock
);
237 void ceph_cleanup_empty_realms(struct ceph_mds_client
*mdsc
)
239 down_write(&mdsc
->snap_rwsem
);
240 __cleanup_empty_realms(mdsc
);
241 up_write(&mdsc
->snap_rwsem
);
245 * adjust the parent realm of a given @realm. adjust child list, and parent
246 * pointers, and ref counts appropriately.
248 * return true if parent was changed, 0 if unchanged, <0 on error.
250 * caller must hold snap_rwsem for write.
252 static int adjust_snap_realm_parent(struct ceph_mds_client
*mdsc
,
253 struct ceph_snap_realm
*realm
,
256 struct ceph_snap_realm
*parent
;
258 if (realm
->parent_ino
== parentino
)
261 parent
= ceph_lookup_snap_realm(mdsc
, parentino
);
263 parent
= ceph_create_snap_realm(mdsc
, parentino
);
265 return PTR_ERR(parent
);
267 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
268 realm
->ino
, realm
, realm
->parent_ino
, realm
->parent
,
271 list_del_init(&realm
->child_item
);
272 ceph_put_snap_realm(mdsc
, realm
->parent
);
274 realm
->parent_ino
= parentino
;
275 realm
->parent
= parent
;
276 ceph_get_snap_realm(mdsc
, parent
);
277 list_add(&realm
->child_item
, &parent
->children
);
282 static int cmpu64_rev(const void *a
, const void *b
)
284 if (*(u64
*)a
< *(u64
*)b
)
286 if (*(u64
*)a
> *(u64
*)b
)
292 static struct ceph_snap_context
*empty_snapc
;
295 * build the snap context for a given realm.
297 static int build_snap_context(struct ceph_snap_realm
*realm
)
299 struct ceph_snap_realm
*parent
= realm
->parent
;
300 struct ceph_snap_context
*snapc
;
302 u32 num
= realm
->num_prior_parent_snaps
+ realm
->num_snaps
;
305 * build parent context, if it hasn't been built.
306 * conservatively estimate that all parent snaps might be
310 if (!parent
->cached_context
) {
311 err
= build_snap_context(parent
);
315 num
+= parent
->cached_context
->num_snaps
;
318 /* do i actually need to update? not if my context seq
319 matches realm seq, and my parents' does to. (this works
320 because we rebuild_snap_realms() works _downward_ in
321 hierarchy after each update.) */
322 if (realm
->cached_context
&&
323 realm
->cached_context
->seq
== realm
->seq
&&
325 realm
->cached_context
->seq
>= parent
->cached_context
->seq
)) {
326 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)"
328 realm
->ino
, realm
, realm
->cached_context
,
329 realm
->cached_context
->seq
,
330 (unsigned int) realm
->cached_context
->num_snaps
);
334 if (num
== 0 && realm
->seq
== empty_snapc
->seq
) {
335 ceph_get_snap_context(empty_snapc
);
340 /* alloc new snap context */
342 if (num
> (SIZE_MAX
- sizeof(*snapc
)) / sizeof(u64
))
344 snapc
= ceph_create_snap_context(num
, GFP_NOFS
);
348 /* build (reverse sorted) snap vector */
350 snapc
->seq
= realm
->seq
;
354 /* include any of parent's snaps occurring _after_ my
355 parent became my parent */
356 for (i
= 0; i
< parent
->cached_context
->num_snaps
; i
++)
357 if (parent
->cached_context
->snaps
[i
] >=
359 snapc
->snaps
[num
++] =
360 parent
->cached_context
->snaps
[i
];
361 if (parent
->cached_context
->seq
> snapc
->seq
)
362 snapc
->seq
= parent
->cached_context
->seq
;
364 memcpy(snapc
->snaps
+ num
, realm
->snaps
,
365 sizeof(u64
)*realm
->num_snaps
);
366 num
+= realm
->num_snaps
;
367 memcpy(snapc
->snaps
+ num
, realm
->prior_parent_snaps
,
368 sizeof(u64
)*realm
->num_prior_parent_snaps
);
369 num
+= realm
->num_prior_parent_snaps
;
371 sort(snapc
->snaps
, num
, sizeof(u64
), cmpu64_rev
, NULL
);
372 snapc
->num_snaps
= num
;
373 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)\n",
374 realm
->ino
, realm
, snapc
, snapc
->seq
,
375 (unsigned int) snapc
->num_snaps
);
378 ceph_put_snap_context(realm
->cached_context
);
379 realm
->cached_context
= snapc
;
384 * if we fail, clear old (incorrect) cached_context... hopefully
385 * we'll have better luck building it later
387 if (realm
->cached_context
) {
388 ceph_put_snap_context(realm
->cached_context
);
389 realm
->cached_context
= NULL
;
391 pr_err("build_snap_context %llx %p fail %d\n", realm
->ino
,
397 * rebuild snap context for the given realm and all of its children.
399 static void rebuild_snap_realms(struct ceph_snap_realm
*realm
)
401 struct ceph_snap_realm
*child
;
403 dout("rebuild_snap_realms %llx %p\n", realm
->ino
, realm
);
404 build_snap_context(realm
);
406 list_for_each_entry(child
, &realm
->children
, child_item
)
407 rebuild_snap_realms(child
);
412 * helper to allocate and decode an array of snapids. free prior
415 static int dup_array(u64
**dst
, __le64
*src
, u32 num
)
421 *dst
= kcalloc(num
, sizeof(u64
), GFP_NOFS
);
424 for (i
= 0; i
< num
; i
++)
425 (*dst
)[i
] = get_unaligned_le64(src
+ i
);
434 * When a snapshot is applied, the size/mtime inode metadata is queued
435 * in a ceph_cap_snap (one for each snapshot) until writeback
436 * completes and the metadata can be flushed back to the MDS.
438 * However, if a (sync) write is currently in-progress when we apply
439 * the snapshot, we have to wait until the write succeeds or fails
440 * (and a final size/mtime is known). In this case the
441 * cap_snap->writing = 1, and is said to be "pending." When the write
442 * finishes, we __ceph_finish_cap_snap().
444 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
447 void ceph_queue_cap_snap(struct ceph_inode_info
*ci
)
449 struct inode
*inode
= &ci
->vfs_inode
;
450 struct ceph_cap_snap
*capsnap
;
453 capsnap
= kzalloc(sizeof(*capsnap
), GFP_NOFS
);
455 pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode
);
459 spin_lock(&ci
->i_ceph_lock
);
460 used
= __ceph_caps_used(ci
);
461 dirty
= __ceph_caps_dirty(ci
);
464 * If there is a write in progress, treat that as a dirty Fw,
465 * even though it hasn't completed yet; by the time we finish
466 * up this capsnap it will be.
468 if (used
& CEPH_CAP_FILE_WR
)
469 dirty
|= CEPH_CAP_FILE_WR
;
471 if (__ceph_have_pending_cap_snap(ci
)) {
472 /* there is no point in queuing multiple "pending" cap_snaps,
473 as no new writes are allowed to start when pending, so any
474 writes in progress now were started before the previous
475 cap_snap. lucky us. */
476 dout("queue_cap_snap %p already pending\n", inode
);
478 } else if (ci
->i_snap_realm
->cached_context
== empty_snapc
) {
479 dout("queue_cap_snap %p empty snapc\n", inode
);
481 } else if (dirty
& (CEPH_CAP_AUTH_EXCL
|CEPH_CAP_XATTR_EXCL
|
482 CEPH_CAP_FILE_EXCL
|CEPH_CAP_FILE_WR
)) {
483 struct ceph_snap_context
*snapc
= ci
->i_head_snapc
;
486 * if we are a sync write, we may need to go to the snaprealm
487 * to get the current snapc.
490 snapc
= ci
->i_snap_realm
->cached_context
;
492 dout("queue_cap_snap %p cap_snap %p queuing under %p %s\n",
493 inode
, capsnap
, snapc
, ceph_cap_string(dirty
));
496 atomic_set(&capsnap
->nref
, 1);
498 INIT_LIST_HEAD(&capsnap
->ci_item
);
499 INIT_LIST_HEAD(&capsnap
->flushing_item
);
501 capsnap
->follows
= snapc
->seq
;
502 capsnap
->issued
= __ceph_caps_issued(ci
, NULL
);
503 capsnap
->dirty
= dirty
;
505 capsnap
->mode
= inode
->i_mode
;
506 capsnap
->uid
= inode
->i_uid
;
507 capsnap
->gid
= inode
->i_gid
;
509 if (dirty
& CEPH_CAP_XATTR_EXCL
) {
510 __ceph_build_xattrs_blob(ci
);
511 capsnap
->xattr_blob
=
512 ceph_buffer_get(ci
->i_xattrs
.blob
);
513 capsnap
->xattr_version
= ci
->i_xattrs
.version
;
515 capsnap
->xattr_blob
= NULL
;
516 capsnap
->xattr_version
= 0;
519 capsnap
->inline_data
= ci
->i_inline_version
!= CEPH_INLINE_NONE
;
521 /* dirty page count moved from _head to this cap_snap;
522 all subsequent writes page dirties occur _after_ this
524 capsnap
->dirty_pages
= ci
->i_wrbuffer_ref_head
;
525 ci
->i_wrbuffer_ref_head
= 0;
526 capsnap
->context
= snapc
;
528 ceph_get_snap_context(ci
->i_snap_realm
->cached_context
);
529 dout(" new snapc is %p\n", ci
->i_head_snapc
);
530 list_add_tail(&capsnap
->ci_item
, &ci
->i_cap_snaps
);
532 if (used
& CEPH_CAP_FILE_WR
) {
533 dout("queue_cap_snap %p cap_snap %p snapc %p"
534 " seq %llu used WR, now pending\n", inode
,
535 capsnap
, snapc
, snapc
->seq
);
536 capsnap
->writing
= 1;
538 /* note mtime, size NOW. */
539 __ceph_finish_cap_snap(ci
, capsnap
);
542 dout("queue_cap_snap %p nothing dirty|writing\n", inode
);
546 spin_unlock(&ci
->i_ceph_lock
);
550 * Finalize the size, mtime for a cap_snap.. that is, settle on final values
551 * to be used for the snapshot, to be flushed back to the mds.
553 * If capsnap can now be flushed, add to snap_flush list, and return 1.
555 * Caller must hold i_ceph_lock.
557 int __ceph_finish_cap_snap(struct ceph_inode_info
*ci
,
558 struct ceph_cap_snap
*capsnap
)
560 struct inode
*inode
= &ci
->vfs_inode
;
561 struct ceph_mds_client
*mdsc
= ceph_sb_to_client(inode
->i_sb
)->mdsc
;
563 BUG_ON(capsnap
->writing
);
564 capsnap
->size
= inode
->i_size
;
565 capsnap
->mtime
= inode
->i_mtime
;
566 capsnap
->atime
= inode
->i_atime
;
567 capsnap
->ctime
= inode
->i_ctime
;
568 capsnap
->time_warp_seq
= ci
->i_time_warp_seq
;
569 if (capsnap
->dirty_pages
) {
570 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
571 "still has %d dirty pages\n", inode
, capsnap
,
572 capsnap
->context
, capsnap
->context
->seq
,
573 ceph_cap_string(capsnap
->dirty
), capsnap
->size
,
574 capsnap
->dirty_pages
);
577 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
578 inode
, capsnap
, capsnap
->context
,
579 capsnap
->context
->seq
, ceph_cap_string(capsnap
->dirty
),
582 spin_lock(&mdsc
->snap_flush_lock
);
583 list_add_tail(&ci
->i_snap_flush_item
, &mdsc
->snap_flush_list
);
584 spin_unlock(&mdsc
->snap_flush_lock
);
585 return 1; /* caller may want to ceph_flush_snaps */
589 * Queue cap_snaps for snap writeback for this realm and its children.
590 * Called under snap_rwsem, so realm topology won't change.
592 static void queue_realm_cap_snaps(struct ceph_snap_realm
*realm
)
594 struct ceph_inode_info
*ci
;
595 struct inode
*lastinode
= NULL
;
596 struct ceph_snap_realm
*child
;
598 dout("queue_realm_cap_snaps %p %llx inodes\n", realm
, realm
->ino
);
600 spin_lock(&realm
->inodes_with_caps_lock
);
601 list_for_each_entry(ci
, &realm
->inodes_with_caps
,
603 struct inode
*inode
= igrab(&ci
->vfs_inode
);
606 spin_unlock(&realm
->inodes_with_caps_lock
);
609 ceph_queue_cap_snap(ci
);
610 spin_lock(&realm
->inodes_with_caps_lock
);
612 spin_unlock(&realm
->inodes_with_caps_lock
);
615 list_for_each_entry(child
, &realm
->children
, child_item
) {
616 dout("queue_realm_cap_snaps %p %llx queue child %p %llx\n",
617 realm
, realm
->ino
, child
, child
->ino
);
618 list_del_init(&child
->dirty_item
);
619 list_add(&child
->dirty_item
, &realm
->dirty_item
);
622 list_del_init(&realm
->dirty_item
);
623 dout("queue_realm_cap_snaps %p %llx done\n", realm
, realm
->ino
);
627 * Parse and apply a snapblob "snap trace" from the MDS. This specifies
628 * the snap realm parameters from a given realm and all of its ancestors,
631 * Caller must hold snap_rwsem for write.
633 int ceph_update_snap_trace(struct ceph_mds_client
*mdsc
,
634 void *p
, void *e
, bool deletion
)
636 struct ceph_mds_snap_realm
*ri
; /* encoded */
637 __le64
*snaps
; /* encoded */
638 __le64
*prior_parent_snaps
; /* encoded */
639 struct ceph_snap_realm
*realm
;
642 LIST_HEAD(dirty_realms
);
644 dout("update_snap_trace deletion=%d\n", deletion
);
646 ceph_decode_need(&p
, e
, sizeof(*ri
), bad
);
649 ceph_decode_need(&p
, e
, sizeof(u64
)*(le32_to_cpu(ri
->num_snaps
) +
650 le32_to_cpu(ri
->num_prior_parent_snaps
)), bad
);
652 p
+= sizeof(u64
) * le32_to_cpu(ri
->num_snaps
);
653 prior_parent_snaps
= p
;
654 p
+= sizeof(u64
) * le32_to_cpu(ri
->num_prior_parent_snaps
);
656 realm
= ceph_lookup_snap_realm(mdsc
, le64_to_cpu(ri
->ino
));
658 realm
= ceph_create_snap_realm(mdsc
, le64_to_cpu(ri
->ino
));
660 err
= PTR_ERR(realm
);
665 /* ensure the parent is correct */
666 err
= adjust_snap_realm_parent(mdsc
, realm
, le64_to_cpu(ri
->parent
));
671 if (le64_to_cpu(ri
->seq
) > realm
->seq
) {
672 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
673 realm
->ino
, realm
, realm
->seq
, le64_to_cpu(ri
->seq
));
674 /* update realm parameters, snap lists */
675 realm
->seq
= le64_to_cpu(ri
->seq
);
676 realm
->created
= le64_to_cpu(ri
->created
);
677 realm
->parent_since
= le64_to_cpu(ri
->parent_since
);
679 realm
->num_snaps
= le32_to_cpu(ri
->num_snaps
);
680 err
= dup_array(&realm
->snaps
, snaps
, realm
->num_snaps
);
684 realm
->num_prior_parent_snaps
=
685 le32_to_cpu(ri
->num_prior_parent_snaps
);
686 err
= dup_array(&realm
->prior_parent_snaps
, prior_parent_snaps
,
687 realm
->num_prior_parent_snaps
);
691 /* queue realm for cap_snap creation */
692 list_add(&realm
->dirty_item
, &dirty_realms
);
695 } else if (!realm
->cached_context
) {
696 dout("update_snap_trace %llx %p seq %lld new\n",
697 realm
->ino
, realm
, realm
->seq
);
700 dout("update_snap_trace %llx %p seq %lld unchanged\n",
701 realm
->ino
, realm
, realm
->seq
);
704 dout("done with %llx %p, invalidated=%d, %p %p\n", realm
->ino
,
705 realm
, invalidate
, p
, e
);
710 /* invalidate when we reach the _end_ (root) of the trace */
712 rebuild_snap_realms(realm
);
715 * queue cap snaps _after_ we've built the new snap contexts,
716 * so that i_head_snapc can be set appropriately.
718 while (!list_empty(&dirty_realms
)) {
719 realm
= list_first_entry(&dirty_realms
, struct ceph_snap_realm
,
721 queue_realm_cap_snaps(realm
);
724 __cleanup_empty_realms(mdsc
);
730 pr_err("update_snap_trace error %d\n", err
);
736 * Send any cap_snaps that are queued for flush. Try to carry
737 * s_mutex across multiple snap flushes to avoid locking overhead.
739 * Caller holds no locks.
741 static void flush_snaps(struct ceph_mds_client
*mdsc
)
743 struct ceph_inode_info
*ci
;
745 struct ceph_mds_session
*session
= NULL
;
747 dout("flush_snaps\n");
748 spin_lock(&mdsc
->snap_flush_lock
);
749 while (!list_empty(&mdsc
->snap_flush_list
)) {
750 ci
= list_first_entry(&mdsc
->snap_flush_list
,
751 struct ceph_inode_info
, i_snap_flush_item
);
752 inode
= &ci
->vfs_inode
;
754 spin_unlock(&mdsc
->snap_flush_lock
);
755 spin_lock(&ci
->i_ceph_lock
);
756 __ceph_flush_snaps(ci
, &session
, 0);
757 spin_unlock(&ci
->i_ceph_lock
);
759 spin_lock(&mdsc
->snap_flush_lock
);
761 spin_unlock(&mdsc
->snap_flush_lock
);
764 mutex_unlock(&session
->s_mutex
);
765 ceph_put_mds_session(session
);
767 dout("flush_snaps done\n");
772 * Handle a snap notification from the MDS.
774 * This can take two basic forms: the simplest is just a snap creation
775 * or deletion notification on an existing realm. This should update the
776 * realm and its children.
778 * The more difficult case is realm creation, due to snap creation at a
779 * new point in the file hierarchy, or due to a rename that moves a file or
780 * directory into another realm.
782 void ceph_handle_snap(struct ceph_mds_client
*mdsc
,
783 struct ceph_mds_session
*session
,
784 struct ceph_msg
*msg
)
786 struct super_block
*sb
= mdsc
->fsc
->sb
;
787 int mds
= session
->s_mds
;
791 struct ceph_snap_realm
*realm
= NULL
;
792 void *p
= msg
->front
.iov_base
;
793 void *e
= p
+ msg
->front
.iov_len
;
794 struct ceph_mds_snap_head
*h
;
795 int num_split_inos
, num_split_realms
;
796 __le64
*split_inos
= NULL
, *split_realms
= NULL
;
798 int locked_rwsem
= 0;
801 if (msg
->front
.iov_len
< sizeof(*h
))
804 op
= le32_to_cpu(h
->op
);
805 split
= le64_to_cpu(h
->split
); /* non-zero if we are splitting an
807 num_split_inos
= le32_to_cpu(h
->num_split_inos
);
808 num_split_realms
= le32_to_cpu(h
->num_split_realms
);
809 trace_len
= le32_to_cpu(h
->trace_len
);
812 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds
,
813 ceph_snap_op_name(op
), split
, trace_len
);
815 mutex_lock(&session
->s_mutex
);
817 mutex_unlock(&session
->s_mutex
);
819 down_write(&mdsc
->snap_rwsem
);
822 if (op
== CEPH_SNAP_OP_SPLIT
) {
823 struct ceph_mds_snap_realm
*ri
;
826 * A "split" breaks part of an existing realm off into
827 * a new realm. The MDS provides a list of inodes
828 * (with caps) and child realms that belong to the new
832 p
+= sizeof(u64
) * num_split_inos
;
834 p
+= sizeof(u64
) * num_split_realms
;
835 ceph_decode_need(&p
, e
, sizeof(*ri
), bad
);
836 /* we will peek at realm info here, but will _not_
837 * advance p, as the realm update will occur below in
838 * ceph_update_snap_trace. */
841 realm
= ceph_lookup_snap_realm(mdsc
, split
);
843 realm
= ceph_create_snap_realm(mdsc
, split
);
847 ceph_get_snap_realm(mdsc
, realm
);
849 dout("splitting snap_realm %llx %p\n", realm
->ino
, realm
);
850 for (i
= 0; i
< num_split_inos
; i
++) {
851 struct ceph_vino vino
= {
852 .ino
= le64_to_cpu(split_inos
[i
]),
855 struct inode
*inode
= ceph_find_inode(sb
, vino
);
856 struct ceph_inode_info
*ci
;
857 struct ceph_snap_realm
*oldrealm
;
861 ci
= ceph_inode(inode
);
863 spin_lock(&ci
->i_ceph_lock
);
864 if (!ci
->i_snap_realm
)
867 * If this inode belongs to a realm that was
868 * created after our new realm, we experienced
869 * a race (due to another split notifications
870 * arriving from a different MDS). So skip
873 if (ci
->i_snap_realm
->created
>
874 le64_to_cpu(ri
->created
)) {
875 dout(" leaving %p in newer realm %llx %p\n",
876 inode
, ci
->i_snap_realm
->ino
,
880 dout(" will move %p to split realm %llx %p\n",
881 inode
, realm
->ino
, realm
);
883 * Move the inode to the new realm
885 spin_lock(&realm
->inodes_with_caps_lock
);
886 list_del_init(&ci
->i_snap_realm_item
);
887 list_add(&ci
->i_snap_realm_item
,
888 &realm
->inodes_with_caps
);
889 oldrealm
= ci
->i_snap_realm
;
890 ci
->i_snap_realm
= realm
;
891 spin_unlock(&realm
->inodes_with_caps_lock
);
892 spin_unlock(&ci
->i_ceph_lock
);
894 ceph_get_snap_realm(mdsc
, realm
);
895 ceph_put_snap_realm(mdsc
, oldrealm
);
901 spin_unlock(&ci
->i_ceph_lock
);
905 /* we may have taken some of the old realm's children. */
906 for (i
= 0; i
< num_split_realms
; i
++) {
907 struct ceph_snap_realm
*child
=
908 ceph_lookup_snap_realm(mdsc
,
909 le64_to_cpu(split_realms
[i
]));
912 adjust_snap_realm_parent(mdsc
, child
, realm
->ino
);
917 * update using the provided snap trace. if we are deleting a
918 * snap, we can avoid queueing cap_snaps.
920 ceph_update_snap_trace(mdsc
, p
, e
,
921 op
== CEPH_SNAP_OP_DESTROY
);
923 if (op
== CEPH_SNAP_OP_SPLIT
)
924 /* we took a reference when we created the realm, above */
925 ceph_put_snap_realm(mdsc
, realm
);
927 __cleanup_empty_realms(mdsc
);
929 up_write(&mdsc
->snap_rwsem
);
935 pr_err("corrupt snap message from mds%d\n", mds
);
939 up_write(&mdsc
->snap_rwsem
);
943 int __init
ceph_snap_init(void)
945 empty_snapc
= ceph_create_snap_context(0, GFP_NOFS
);
948 empty_snapc
->seq
= 1;
952 void ceph_snap_exit(void)
954 ceph_put_snap_context(empty_snapc
);
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