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Yehuda Sadeh3d14c5d2010-04-06 15:14:15 -07001#include <linux/ceph/ceph_debug.h>
Sage Weil963b61e2009-10-06 11:31:12 -07002
Sage Weil963b61e2009-10-06 11:31:12 -07003#include <linux/sort.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +09004#include <linux/slab.h>
Sage Weil963b61e2009-10-06 11:31:12 -07005
6#include "super.h"
Yehuda Sadeh3d14c5d2010-04-06 15:14:15 -07007#include "mds_client.h"
8
9#include <linux/ceph/decode.h>
Sage Weil963b61e2009-10-06 11:31:12 -070010
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_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);
77 }
78
79 atomic_inc(&realm->nref);
80}
81
Sage Weila105f002010-02-15 14:37:55 -080082static void __insert_snap_realm(struct rb_root *root,
83 struct ceph_snap_realm *new)
84{
85 struct rb_node **p = &root->rb_node;
86 struct rb_node *parent = NULL;
87 struct ceph_snap_realm *r = NULL;
88
89 while (*p) {
90 parent = *p;
91 r = rb_entry(parent, struct ceph_snap_realm, node);
92 if (new->ino < r->ino)
93 p = &(*p)->rb_left;
94 else if (new->ino > r->ino)
95 p = &(*p)->rb_right;
96 else
97 BUG();
98 }
99
100 rb_link_node(&new->node, parent, p);
101 rb_insert_color(&new->node, root);
102}
103
Sage Weil963b61e2009-10-06 11:31:12 -0700104/*
105 * create and get the realm rooted at @ino and bump its ref count.
106 *
107 * caller must hold snap_rwsem for write.
108 */
109static struct ceph_snap_realm *ceph_create_snap_realm(
110 struct ceph_mds_client *mdsc,
111 u64 ino)
112{
113 struct ceph_snap_realm *realm;
114
115 realm = kzalloc(sizeof(*realm), GFP_NOFS);
116 if (!realm)
117 return ERR_PTR(-ENOMEM);
118
Sage Weil963b61e2009-10-06 11:31:12 -0700119 atomic_set(&realm->nref, 0); /* tree does not take a ref */
120 realm->ino = ino;
121 INIT_LIST_HEAD(&realm->children);
122 INIT_LIST_HEAD(&realm->child_item);
123 INIT_LIST_HEAD(&realm->empty_item);
Sage Weilae00d4f2010-09-16 16:26:51 -0700124 INIT_LIST_HEAD(&realm->dirty_item);
Sage Weil963b61e2009-10-06 11:31:12 -0700125 INIT_LIST_HEAD(&realm->inodes_with_caps);
126 spin_lock_init(&realm->inodes_with_caps_lock);
Sage Weila105f002010-02-15 14:37:55 -0800127 __insert_snap_realm(&mdsc->snap_realms, realm);
Sage Weil963b61e2009-10-06 11:31:12 -0700128 dout("create_snap_realm %llx %p\n", realm->ino, realm);
129 return realm;
130}
131
132/*
Sage Weila105f002010-02-15 14:37:55 -0800133 * lookup the realm rooted at @ino.
Sage Weil963b61e2009-10-06 11:31:12 -0700134 *
135 * caller must hold snap_rwsem for write.
136 */
137struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
138 u64 ino)
139{
Sage Weila105f002010-02-15 14:37:55 -0800140 struct rb_node *n = mdsc->snap_realms.rb_node;
141 struct ceph_snap_realm *r;
Sage Weil963b61e2009-10-06 11:31:12 -0700142
Sage Weila105f002010-02-15 14:37:55 -0800143 while (n) {
144 r = rb_entry(n, struct ceph_snap_realm, node);
145 if (ino < r->ino)
146 n = n->rb_left;
147 else if (ino > r->ino)
148 n = n->rb_right;
149 else {
150 dout("lookup_snap_realm %llx %p\n", r->ino, r);
151 return r;
152 }
153 }
154 return NULL;
Sage Weil963b61e2009-10-06 11:31:12 -0700155}
156
157static void __put_snap_realm(struct ceph_mds_client *mdsc,
158 struct ceph_snap_realm *realm);
159
160/*
161 * called with snap_rwsem (write)
162 */
163static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
164 struct ceph_snap_realm *realm)
165{
166 dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
167
Sage Weila105f002010-02-15 14:37:55 -0800168 rb_erase(&realm->node, &mdsc->snap_realms);
Sage Weil963b61e2009-10-06 11:31:12 -0700169
170 if (realm->parent) {
171 list_del_init(&realm->child_item);
172 __put_snap_realm(mdsc, realm->parent);
173 }
174
175 kfree(realm->prior_parent_snaps);
176 kfree(realm->snaps);
177 ceph_put_snap_context(realm->cached_context);
178 kfree(realm);
179}
180
181/*
182 * caller holds snap_rwsem (write)
183 */
184static void __put_snap_realm(struct ceph_mds_client *mdsc,
185 struct ceph_snap_realm *realm)
186{
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);
191}
192
193/*
194 * caller needn't hold any locks
195 */
196void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
197 struct ceph_snap_realm *realm)
198{
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))
202 return;
203
204 if (down_write_trylock(&mdsc->snap_rwsem)) {
205 __destroy_snap_realm(mdsc, realm);
206 up_write(&mdsc->snap_rwsem);
207 } else {
208 spin_lock(&mdsc->snap_empty_lock);
Henry C Changa26a1852011-05-11 10:29:53 +0000209 list_add(&realm->empty_item, &mdsc->snap_empty);
Sage Weil963b61e2009-10-06 11:31:12 -0700210 spin_unlock(&mdsc->snap_empty_lock);
211 }
212}
213
214/*
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
217 * used.
218 *
219 * Called under snap_rwsem (write)
220 */
221static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
222{
223 struct ceph_snap_realm *realm;
224
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);
233 }
234 spin_unlock(&mdsc->snap_empty_lock);
235}
236
237void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc)
238{
239 down_write(&mdsc->snap_rwsem);
240 __cleanup_empty_realms(mdsc);
241 up_write(&mdsc->snap_rwsem);
242}
243
244/*
245 * adjust the parent realm of a given @realm. adjust child list, and parent
246 * pointers, and ref counts appropriately.
247 *
248 * return true if parent was changed, 0 if unchanged, <0 on error.
249 *
250 * caller must hold snap_rwsem for write.
251 */
252static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
253 struct ceph_snap_realm *realm,
254 u64 parentino)
255{
256 struct ceph_snap_realm *parent;
257
258 if (realm->parent_ino == parentino)
259 return 0;
260
261 parent = ceph_lookup_snap_realm(mdsc, parentino);
Sage Weil963b61e2009-10-06 11:31:12 -0700262 if (!parent) {
263 parent = ceph_create_snap_realm(mdsc, parentino);
264 if (IS_ERR(parent))
265 return PTR_ERR(parent);
266 }
267 dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n",
268 realm->ino, realm, realm->parent_ino, realm->parent,
269 parentino, parent);
270 if (realm->parent) {
271 list_del_init(&realm->child_item);
272 ceph_put_snap_realm(mdsc, realm->parent);
273 }
274 realm->parent_ino = parentino;
275 realm->parent = parent;
276 ceph_get_snap_realm(mdsc, parent);
277 list_add(&realm->child_item, &parent->children);
278 return 1;
279}
280
281
282static int cmpu64_rev(const void *a, const void *b)
283{
284 if (*(u64 *)a < *(u64 *)b)
285 return 1;
286 if (*(u64 *)a > *(u64 *)b)
287 return -1;
288 return 0;
289}
290
Yan, Zheng97c85a82014-11-06 15:09:41 +0800291
292static struct ceph_snap_context *empty_snapc;
293
Sage Weil963b61e2009-10-06 11:31:12 -0700294/*
295 * build the snap context for a given realm.
296 */
297static int build_snap_context(struct ceph_snap_realm *realm)
298{
299 struct ceph_snap_realm *parent = realm->parent;
300 struct ceph_snap_context *snapc;
301 int err = 0;
Alex Elderaa711ee2012-07-13 20:35:11 -0500302 u32 num = realm->num_prior_parent_snaps + realm->num_snaps;
Sage Weil963b61e2009-10-06 11:31:12 -0700303
304 /*
305 * build parent context, if it hasn't been built.
306 * conservatively estimate that all parent snaps might be
307 * included by us.
308 */
309 if (parent) {
310 if (!parent->cached_context) {
311 err = build_snap_context(parent);
312 if (err)
313 goto fail;
314 }
315 num += parent->cached_context->num_snaps;
316 }
317
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 &&
Sage Weilec4318bc2010-03-19 13:24:39 -0700323 realm->cached_context->seq == realm->seq &&
Sage Weil963b61e2009-10-06 11:31:12 -0700324 (!parent ||
Sage Weilec4318bc2010-03-19 13:24:39 -0700325 realm->cached_context->seq >= parent->cached_context->seq)) {
Alex Elderaa711ee2012-07-13 20:35:11 -0500326 dout("build_snap_context %llx %p: %p seq %lld (%u snaps)"
Sage Weil963b61e2009-10-06 11:31:12 -0700327 " (unchanged)\n",
328 realm->ino, realm, realm->cached_context,
329 realm->cached_context->seq,
Alex Elderaa711ee2012-07-13 20:35:11 -0500330 (unsigned int) realm->cached_context->num_snaps);
Sage Weil963b61e2009-10-06 11:31:12 -0700331 return 0;
332 }
333
Yan, Zheng97c85a82014-11-06 15:09:41 +0800334 if (num == 0 && realm->seq == empty_snapc->seq) {
335 ceph_get_snap_context(empty_snapc);
336 snapc = empty_snapc;
337 goto done;
338 }
339
Sage Weil963b61e2009-10-06 11:31:12 -0700340 /* alloc new snap context */
341 err = -ENOMEM;
Xi Wanga3860c12012-05-31 16:26:04 -0700342 if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
Sage Weil963b61e2009-10-06 11:31:12 -0700343 goto fail;
Alex Elder812164f82013-04-30 00:44:32 -0500344 snapc = ceph_create_snap_context(num, GFP_NOFS);
Sage Weil963b61e2009-10-06 11:31:12 -0700345 if (!snapc)
346 goto fail;
Sage Weil963b61e2009-10-06 11:31:12 -0700347
348 /* build (reverse sorted) snap vector */
349 num = 0;
350 snapc->seq = realm->seq;
351 if (parent) {
Alex Elderaa711ee2012-07-13 20:35:11 -0500352 u32 i;
353
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300354 /* include any of parent's snaps occurring _after_ my
Sage Weil963b61e2009-10-06 11:31:12 -0700355 parent became my parent */
356 for (i = 0; i < parent->cached_context->num_snaps; i++)
357 if (parent->cached_context->snaps[i] >=
358 realm->parent_since)
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;
363 }
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;
370
371 sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL);
372 snapc->num_snaps = num;
Alex Elderaa711ee2012-07-13 20:35:11 -0500373 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);
Sage Weil963b61e2009-10-06 11:31:12 -0700376
Yan, Zheng97c85a82014-11-06 15:09:41 +0800377done:
SF Markus Elfringe96a6502014-11-02 15:20:59 +0100378 ceph_put_snap_context(realm->cached_context);
Sage Weil963b61e2009-10-06 11:31:12 -0700379 realm->cached_context = snapc;
380 return 0;
381
382fail:
383 /*
384 * if we fail, clear old (incorrect) cached_context... hopefully
385 * we'll have better luck building it later
386 */
387 if (realm->cached_context) {
388 ceph_put_snap_context(realm->cached_context);
389 realm->cached_context = NULL;
390 }
391 pr_err("build_snap_context %llx %p fail %d\n", realm->ino,
392 realm, err);
393 return err;
394}
395
396/*
397 * rebuild snap context for the given realm and all of its children.
398 */
399static void rebuild_snap_realms(struct ceph_snap_realm *realm)
400{
401 struct ceph_snap_realm *child;
402
403 dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
404 build_snap_context(realm);
405
406 list_for_each_entry(child, &realm->children, child_item)
407 rebuild_snap_realms(child);
408}
409
410
411/*
412 * helper to allocate and decode an array of snapids. free prior
413 * instance, if any.
414 */
Alex Elderaa711ee2012-07-13 20:35:11 -0500415static int dup_array(u64 **dst, __le64 *src, u32 num)
Sage Weil963b61e2009-10-06 11:31:12 -0700416{
Alex Elderaa711ee2012-07-13 20:35:11 -0500417 u32 i;
Sage Weil963b61e2009-10-06 11:31:12 -0700418
419 kfree(*dst);
420 if (num) {
421 *dst = kcalloc(num, sizeof(u64), GFP_NOFS);
422 if (!*dst)
423 return -ENOMEM;
424 for (i = 0; i < num; i++)
425 (*dst)[i] = get_unaligned_le64(src + i);
426 } else {
427 *dst = NULL;
428 }
429 return 0;
430}
431
432
433/*
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.
437 *
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().
443 *
444 * Caller must hold snap_rwsem for read (i.e., the realm topology won't
445 * change).
446 */
Sage Weilfc837c8f2010-04-13 11:41:22 -0700447void ceph_queue_cap_snap(struct ceph_inode_info *ci)
Sage Weil963b61e2009-10-06 11:31:12 -0700448{
449 struct inode *inode = &ci->vfs_inode;
450 struct ceph_cap_snap *capsnap;
Sage Weil4a625be2010-08-22 15:03:56 -0700451 int used, dirty;
Sage Weil963b61e2009-10-06 11:31:12 -0700452
453 capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
454 if (!capsnap) {
455 pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
456 return;
457 }
458
Sage Weilbe655592011-11-30 09:47:09 -0800459 spin_lock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700460 used = __ceph_caps_used(ci);
Sage Weil4a625be2010-08-22 15:03:56 -0700461 dirty = __ceph_caps_dirty(ci);
Sage Weilaf0ed562011-07-26 11:26:31 -0700462
463 /*
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.
467 */
468 if (used & CEPH_CAP_FILE_WR)
469 dirty |= CEPH_CAP_FILE_WR;
470
Sage Weil963b61e2009-10-06 11:31:12 -0700471 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. */
Sage Weilfc837c8f2010-04-13 11:41:22 -0700476 dout("queue_cap_snap %p already pending\n", inode);
Sage Weil963b61e2009-10-06 11:31:12 -0700477 kfree(capsnap);
Yan, Zheng97c85a82014-11-06 15:09:41 +0800478 } else if (ci->i_snap_realm->cached_context == empty_snapc) {
479 dout("queue_cap_snap %p empty snapc\n", inode);
480 kfree(capsnap);
Sage Weile77dc3e2011-07-26 11:26:41 -0700481 } else if (dirty & (CEPH_CAP_AUTH_EXCL|CEPH_CAP_XATTR_EXCL|
482 CEPH_CAP_FILE_EXCL|CEPH_CAP_FILE_WR)) {
Sage Weilfc837c8f2010-04-13 11:41:22 -0700483 struct ceph_snap_context *snapc = ci->i_head_snapc;
484
Sage Weilaf0ed562011-07-26 11:26:31 -0700485 /*
486 * if we are a sync write, we may need to go to the snaprealm
487 * to get the current snapc.
488 */
489 if (!snapc)
490 snapc = ci->i_snap_realm->cached_context;
491
492 dout("queue_cap_snap %p cap_snap %p queuing under %p %s\n",
493 inode, capsnap, snapc, ceph_cap_string(dirty));
Dave Chinner0444d762011-03-29 18:08:50 +1100494 ihold(inode);
495
Sage Weil963b61e2009-10-06 11:31:12 -0700496 atomic_set(&capsnap->nref, 1);
497 capsnap->ci = ci;
498 INIT_LIST_HEAD(&capsnap->ci_item);
499 INIT_LIST_HEAD(&capsnap->flushing_item);
500
Sage Weil8bef9232010-09-14 15:45:44 -0700501 capsnap->follows = snapc->seq;
Sage Weil963b61e2009-10-06 11:31:12 -0700502 capsnap->issued = __ceph_caps_issued(ci, NULL);
Sage Weil4a625be2010-08-22 15:03:56 -0700503 capsnap->dirty = dirty;
Sage Weil963b61e2009-10-06 11:31:12 -0700504
505 capsnap->mode = inode->i_mode;
506 capsnap->uid = inode->i_uid;
507 capsnap->gid = inode->i_gid;
508
Sage Weil4a625be2010-08-22 15:03:56 -0700509 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;
514 } else {
515 capsnap->xattr_blob = NULL;
516 capsnap->xattr_version = 0;
517 }
Sage Weil963b61e2009-10-06 11:31:12 -0700518
Yan, Zhenge20d2582014-11-14 22:39:13 +0800519 capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
520
Sage Weil963b61e2009-10-06 11:31:12 -0700521 /* dirty page count moved from _head to this cap_snap;
522 all subsequent writes page dirties occur _after_ this
523 snapshot. */
524 capsnap->dirty_pages = ci->i_wrbuffer_ref_head;
525 ci->i_wrbuffer_ref_head = 0;
Sage Weilfc837c8f2010-04-13 11:41:22 -0700526 capsnap->context = snapc;
Sage Weil7d8cb262010-08-24 08:44:16 -0700527 ci->i_head_snapc =
528 ceph_get_snap_context(ci->i_snap_realm->cached_context);
529 dout(" new snapc is %p\n", ci->i_head_snapc);
Sage Weil963b61e2009-10-06 11:31:12 -0700530 list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);
531
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;
537 } else {
538 /* note mtime, size NOW. */
539 __ceph_finish_cap_snap(ci, capsnap);
540 }
541 } else {
542 dout("queue_cap_snap %p nothing dirty|writing\n", inode);
543 kfree(capsnap);
544 }
545
Sage Weilbe655592011-11-30 09:47:09 -0800546 spin_unlock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700547}
548
549/*
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.
552 *
553 * If capsnap can now be flushed, add to snap_flush list, and return 1.
554 *
Sage Weilbe655592011-11-30 09:47:09 -0800555 * Caller must hold i_ceph_lock.
Sage Weil963b61e2009-10-06 11:31:12 -0700556 */
557int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
558 struct ceph_cap_snap *capsnap)
559{
560 struct inode *inode = &ci->vfs_inode;
Yehuda Sadeh3d14c5d2010-04-06 15:14:15 -0700561 struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
Sage Weil963b61e2009-10-06 11:31:12 -0700562
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) {
Sage Weil819ccbf2010-04-01 09:33:46 -0700570 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu "
Sage Weil963b61e2009-10-06 11:31:12 -0700571 "still has %d dirty pages\n", inode, capsnap,
572 capsnap->context, capsnap->context->seq,
Sage Weil819ccbf2010-04-01 09:33:46 -0700573 ceph_cap_string(capsnap->dirty), capsnap->size,
574 capsnap->dirty_pages);
Sage Weil963b61e2009-10-06 11:31:12 -0700575 return 0;
576 }
Sage Weil819ccbf2010-04-01 09:33:46 -0700577 dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n",
Sage Weil963b61e2009-10-06 11:31:12 -0700578 inode, capsnap, capsnap->context,
Sage Weil819ccbf2010-04-01 09:33:46 -0700579 capsnap->context->seq, ceph_cap_string(capsnap->dirty),
580 capsnap->size);
Sage Weil963b61e2009-10-06 11:31:12 -0700581
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 */
586}
587
Sage Weiled326042010-08-16 13:37:31 -0700588/*
589 * Queue cap_snaps for snap writeback for this realm and its children.
590 * Called under snap_rwsem, so realm topology won't change.
591 */
592static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
593{
594 struct ceph_inode_info *ci;
595 struct inode *lastinode = NULL;
596 struct ceph_snap_realm *child;
597
598 dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
599
600 spin_lock(&realm->inodes_with_caps_lock);
601 list_for_each_entry(ci, &realm->inodes_with_caps,
602 i_snap_realm_item) {
603 struct inode *inode = igrab(&ci->vfs_inode);
604 if (!inode)
605 continue;
606 spin_unlock(&realm->inodes_with_caps_lock);
SF Markus Elfringe96a6502014-11-02 15:20:59 +0100607 iput(lastinode);
Sage Weiled326042010-08-16 13:37:31 -0700608 lastinode = inode;
609 ceph_queue_cap_snap(ci);
610 spin_lock(&realm->inodes_with_caps_lock);
611 }
612 spin_unlock(&realm->inodes_with_caps_lock);
SF Markus Elfringe96a6502014-11-02 15:20:59 +0100613 iput(lastinode);
Sage Weiled326042010-08-16 13:37:31 -0700614
Sage Weile8e1ba962011-02-04 20:45:58 -0800615 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);
620 }
Sage Weiled326042010-08-16 13:37:31 -0700621
Sage Weile8e1ba962011-02-04 20:45:58 -0800622 list_del_init(&realm->dirty_item);
Sage Weiled326042010-08-16 13:37:31 -0700623 dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
624}
Sage Weil963b61e2009-10-06 11:31:12 -0700625
626/*
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,
629 * up to the root.
630 *
631 * Caller must hold snap_rwsem for write.
632 */
633int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
634 void *p, void *e, bool deletion)
635{
636 struct ceph_mds_snap_realm *ri; /* encoded */
637 __le64 *snaps; /* encoded */
638 __le64 *prior_parent_snaps; /* encoded */
639 struct ceph_snap_realm *realm;
640 int invalidate = 0;
641 int err = -ENOMEM;
Sage Weilae00d4f2010-09-16 16:26:51 -0700642 LIST_HEAD(dirty_realms);
Sage Weil963b61e2009-10-06 11:31:12 -0700643
644 dout("update_snap_trace deletion=%d\n", deletion);
645more:
646 ceph_decode_need(&p, e, sizeof(*ri), bad);
647 ri = p;
648 p += sizeof(*ri);
649 ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
650 le32_to_cpu(ri->num_prior_parent_snaps)), bad);
651 snaps = p;
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);
655
656 realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
Sage Weil963b61e2009-10-06 11:31:12 -0700657 if (!realm) {
658 realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
659 if (IS_ERR(realm)) {
660 err = PTR_ERR(realm);
661 goto fail;
662 }
663 }
664
Sage Weil963b61e2009-10-06 11:31:12 -0700665 /* ensure the parent is correct */
666 err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
667 if (err < 0)
668 goto fail;
669 invalidate += err;
670
671 if (le64_to_cpu(ri->seq) > realm->seq) {
Sage Weilae00d4f2010-09-16 16:26:51 -0700672 dout("update_snap_trace updating %llx %p %lld -> %lld\n",
673 realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
Sage Weil963b61e2009-10-06 11:31:12 -0700674 /* 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);
678
679 realm->num_snaps = le32_to_cpu(ri->num_snaps);
680 err = dup_array(&realm->snaps, snaps, realm->num_snaps);
681 if (err < 0)
682 goto fail;
683
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);
688 if (err < 0)
689 goto fail;
690
Sage Weilae00d4f2010-09-16 16:26:51 -0700691 /* queue realm for cap_snap creation */
692 list_add(&realm->dirty_item, &dirty_realms);
693
Sage Weil963b61e2009-10-06 11:31:12 -0700694 invalidate = 1;
695 } else if (!realm->cached_context) {
Sage Weilae00d4f2010-09-16 16:26:51 -0700696 dout("update_snap_trace %llx %p seq %lld new\n",
697 realm->ino, realm, realm->seq);
Sage Weil963b61e2009-10-06 11:31:12 -0700698 invalidate = 1;
Sage Weilae00d4f2010-09-16 16:26:51 -0700699 } else {
700 dout("update_snap_trace %llx %p seq %lld unchanged\n",
701 realm->ino, realm, realm->seq);
Sage Weil963b61e2009-10-06 11:31:12 -0700702 }
703
704 dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino,
705 realm, invalidate, p, e);
706
707 if (p < e)
708 goto more;
709
710 /* invalidate when we reach the _end_ (root) of the trace */
711 if (invalidate)
712 rebuild_snap_realms(realm);
713
Sage Weilae00d4f2010-09-16 16:26:51 -0700714 /*
715 * queue cap snaps _after_ we've built the new snap contexts,
716 * so that i_head_snapc can be set appropriately.
717 */
Sage Weile8e1ba962011-02-04 20:45:58 -0800718 while (!list_empty(&dirty_realms)) {
719 realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
720 dirty_item);
Sage Weilae00d4f2010-09-16 16:26:51 -0700721 queue_realm_cap_snaps(realm);
722 }
723
Sage Weil963b61e2009-10-06 11:31:12 -0700724 __cleanup_empty_realms(mdsc);
725 return 0;
726
727bad:
728 err = -EINVAL;
729fail:
730 pr_err("update_snap_trace error %d\n", err);
731 return err;
732}
733
734
735/*
736 * Send any cap_snaps that are queued for flush. Try to carry
737 * s_mutex across multiple snap flushes to avoid locking overhead.
738 *
739 * Caller holds no locks.
740 */
741static void flush_snaps(struct ceph_mds_client *mdsc)
742{
743 struct ceph_inode_info *ci;
744 struct inode *inode;
745 struct ceph_mds_session *session = NULL;
746
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;
Sage Weil70b666c2011-05-27 09:24:26 -0700753 ihold(inode);
Sage Weil963b61e2009-10-06 11:31:12 -0700754 spin_unlock(&mdsc->snap_flush_lock);
Sage Weilbe655592011-11-30 09:47:09 -0800755 spin_lock(&ci->i_ceph_lock);
Sage Weile8351242010-09-17 08:03:08 -0700756 __ceph_flush_snaps(ci, &session, 0);
Sage Weilbe655592011-11-30 09:47:09 -0800757 spin_unlock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700758 iput(inode);
759 spin_lock(&mdsc->snap_flush_lock);
760 }
761 spin_unlock(&mdsc->snap_flush_lock);
762
763 if (session) {
764 mutex_unlock(&session->s_mutex);
765 ceph_put_mds_session(session);
766 }
767 dout("flush_snaps done\n");
768}
769
770
771/*
772 * Handle a snap notification from the MDS.
773 *
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.
777 *
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.
781 */
782void ceph_handle_snap(struct ceph_mds_client *mdsc,
Sage Weil2600d2d2010-02-22 15:12:16 -0800783 struct ceph_mds_session *session,
Sage Weil963b61e2009-10-06 11:31:12 -0700784 struct ceph_msg *msg)
785{
Yehuda Sadeh3d14c5d2010-04-06 15:14:15 -0700786 struct super_block *sb = mdsc->fsc->sb;
Sage Weil2600d2d2010-02-22 15:12:16 -0800787 int mds = session->s_mds;
Sage Weil963b61e2009-10-06 11:31:12 -0700788 u64 split;
789 int op;
790 int trace_len;
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;
797 int i;
798 int locked_rwsem = 0;
799
Sage Weil963b61e2009-10-06 11:31:12 -0700800 /* decode */
801 if (msg->front.iov_len < sizeof(*h))
802 goto bad;
803 h = p;
804 op = le32_to_cpu(h->op);
805 split = le64_to_cpu(h->split); /* non-zero if we are splitting an
806 * existing realm */
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);
810 p += sizeof(*h);
811
812 dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds,
813 ceph_snap_op_name(op), split, trace_len);
814
Sage Weil963b61e2009-10-06 11:31:12 -0700815 mutex_lock(&session->s_mutex);
816 session->s_seq++;
817 mutex_unlock(&session->s_mutex);
818
819 down_write(&mdsc->snap_rwsem);
820 locked_rwsem = 1;
821
822 if (op == CEPH_SNAP_OP_SPLIT) {
823 struct ceph_mds_snap_realm *ri;
824
825 /*
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
829 * child.
830 */
831 split_inos = p;
832 p += sizeof(u64) * num_split_inos;
833 split_realms = p;
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. */
839 ri = p;
840
841 realm = ceph_lookup_snap_realm(mdsc, split);
Sage Weil963b61e2009-10-06 11:31:12 -0700842 if (!realm) {
843 realm = ceph_create_snap_realm(mdsc, split);
844 if (IS_ERR(realm))
845 goto out;
846 }
847 ceph_get_snap_realm(mdsc, realm);
848
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]),
853 .snap = CEPH_NOSNAP,
854 };
855 struct inode *inode = ceph_find_inode(sb, vino);
856 struct ceph_inode_info *ci;
Sage Weilae00d4f2010-09-16 16:26:51 -0700857 struct ceph_snap_realm *oldrealm;
Sage Weil963b61e2009-10-06 11:31:12 -0700858
859 if (!inode)
860 continue;
861 ci = ceph_inode(inode);
862
Sage Weilbe655592011-11-30 09:47:09 -0800863 spin_lock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700864 if (!ci->i_snap_realm)
865 goto skip_inode;
866 /*
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
871 * this inode.
872 */
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,
877 ci->i_snap_realm);
878 goto skip_inode;
879 }
880 dout(" will move %p to split realm %llx %p\n",
881 inode, realm->ino, realm);
882 /*
Sage Weilae00d4f2010-09-16 16:26:51 -0700883 * Move the inode to the new realm
Sage Weil963b61e2009-10-06 11:31:12 -0700884 */
Sage Weil052bb342010-03-09 12:52:26 -0800885 spin_lock(&realm->inodes_with_caps_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700886 list_del_init(&ci->i_snap_realm_item);
Sage Weilae00d4f2010-09-16 16:26:51 -0700887 list_add(&ci->i_snap_realm_item,
888 &realm->inodes_with_caps);
889 oldrealm = ci->i_snap_realm;
890 ci->i_snap_realm = realm;
Sage Weil052bb342010-03-09 12:52:26 -0800891 spin_unlock(&realm->inodes_with_caps_lock);
Sage Weilbe655592011-11-30 09:47:09 -0800892 spin_unlock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700893
Sage Weilae00d4f2010-09-16 16:26:51 -0700894 ceph_get_snap_realm(mdsc, realm);
895 ceph_put_snap_realm(mdsc, oldrealm);
Sage Weil963b61e2009-10-06 11:31:12 -0700896
897 iput(inode);
898 continue;
899
900skip_inode:
Sage Weilbe655592011-11-30 09:47:09 -0800901 spin_unlock(&ci->i_ceph_lock);
Sage Weil963b61e2009-10-06 11:31:12 -0700902 iput(inode);
903 }
904
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]));
Sage Weil963b61e2009-10-06 11:31:12 -0700910 if (!child)
911 continue;
912 adjust_snap_realm_parent(mdsc, child, realm->ino);
913 }
914 }
915
916 /*
917 * update using the provided snap trace. if we are deleting a
918 * snap, we can avoid queueing cap_snaps.
919 */
920 ceph_update_snap_trace(mdsc, p, e,
921 op == CEPH_SNAP_OP_DESTROY);
922
Sage Weilae00d4f2010-09-16 16:26:51 -0700923 if (op == CEPH_SNAP_OP_SPLIT)
Sage Weil963b61e2009-10-06 11:31:12 -0700924 /* we took a reference when we created the realm, above */
925 ceph_put_snap_realm(mdsc, realm);
Sage Weil963b61e2009-10-06 11:31:12 -0700926
927 __cleanup_empty_realms(mdsc);
928
929 up_write(&mdsc->snap_rwsem);
930
931 flush_snaps(mdsc);
932 return;
933
934bad:
935 pr_err("corrupt snap message from mds%d\n", mds);
Sage Weil9ec7cab2009-12-14 15:13:47 -0800936 ceph_msg_dump(msg);
Sage Weil963b61e2009-10-06 11:31:12 -0700937out:
938 if (locked_rwsem)
939 up_write(&mdsc->snap_rwsem);
940 return;
941}
942
Yan, Zheng97c85a82014-11-06 15:09:41 +0800943int __init ceph_snap_init(void)
944{
945 empty_snapc = ceph_create_snap_context(0, GFP_NOFS);
946 if (!empty_snapc)
947 return -ENOMEM;
948 empty_snapc->seq = 1;
949 return 0;
950}
Sage Weil963b61e2009-10-06 11:31:12 -0700951
Yan, Zheng97c85a82014-11-06 15:09:41 +0800952void ceph_snap_exit(void)
953{
954 ceph_put_snap_context(empty_snapc);
955}