~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/ceph/snap.c

Version: ~ [ linux-5.13-rc7 ] ~ [ linux-5.12.12 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.45 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.127 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.195 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.237 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.273 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.273 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp