1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/ceph/ceph_debug.h>
3 
4 #include <linux/fs.h>
5 #include <linux/sort.h>
6 #include <linux/slab.h>
7 #include <linux/iversion.h>
8 #include "super.h"
9 #include "mds_client.h"
10 #include <linux/ceph/decode.h>
11 
12 /* unused map expires after 5 minutes */
13 #define CEPH_SNAPID_MAP_TIMEOUT	(5 * 60 * HZ)
14 
15 /*
16  * Snapshots in ceph are driven in large part by cooperation from the
17  * client.  In contrast to local file systems or file servers that
18  * implement snapshots at a single point in the system, ceph's
19  * distributed access to storage requires clients to help decide
20  * whether a write logically occurs before or after a recently created
21  * snapshot.
22  *
23  * This provides a perfect instantanous client-wide snapshot.  Between
24  * clients, however, snapshots may appear to be applied at slightly
25  * different points in time, depending on delays in delivering the
26  * snapshot notification.
27  *
28  * Snapshots are _not_ file system-wide.  Instead, each snapshot
29  * applies to the subdirectory nested beneath some directory.  This
30  * effectively divides the hierarchy into multiple "realms," where all
31  * of the files contained by each realm share the same set of
32  * snapshots.  An individual realm's snap set contains snapshots
33  * explicitly created on that realm, as well as any snaps in its
34  * parent's snap set _after_ the point at which the parent became it's
35  * parent (due to, say, a rename).  Similarly, snaps from prior parents
36  * during the time intervals during which they were the parent are included.
37  *
38  * The client is spared most of this detail, fortunately... it must only
39  * maintains a hierarchy of realms reflecting the current parent/child
40  * realm relationship, and for each realm has an explicit list of snaps
41  * inherited from prior parents.
42  *
43  * A snap_realm struct is maintained for realms containing every inode
44  * with an open cap in the system.  (The needed snap realm information is
45  * provided by the MDS whenever a cap is issued, i.e., on open.)  A 'seq'
46  * version number is used to ensure that as realm parameters change (new
47  * snapshot, new parent, etc.) the client's realm hierarchy is updated.
48  *
49  * The realm hierarchy drives the generation of a 'snap context' for each
50  * realm, which simply lists the resulting set of snaps for the realm.  This
51  * is attached to any writes sent to OSDs.
52  */
53 /*
54  * Unfortunately error handling is a bit mixed here.  If we get a snap
55  * update, but don't have enough memory to update our realm hierarchy,
56  * it's not clear what we can do about it (besides complaining to the
57  * console).
58  */
59 
60 
61 /*
62  * increase ref count for the realm
63  *
64  * caller must hold snap_rwsem.
65  */
ceph_get_snap_realm(struct ceph_mds_client * mdsc,struct ceph_snap_realm * realm)66 void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
67 			 struct ceph_snap_realm *realm)
68 {
69 	lockdep_assert_held(&mdsc->snap_rwsem);
70 
71 	/*
72 	 * The 0->1 and 1->0 transitions must take the snap_empty_lock
73 	 * atomically with the refcount change. Go ahead and bump the
74 	 * nref here, unless it's 0, in which case we take the spinlock
75 	 * and then do the increment and remove it from the list.
76 	 */
77 	if (atomic_inc_not_zero(&realm->nref))
78 		return;
79 
80 	spin_lock(&mdsc->snap_empty_lock);
81 	if (atomic_inc_return(&realm->nref) == 1)
82 		list_del_init(&realm->empty_item);
83 	spin_unlock(&mdsc->snap_empty_lock);
84 }
85 
__insert_snap_realm(struct rb_root * root,struct ceph_snap_realm * new)86 static void __insert_snap_realm(struct rb_root *root,
87 				struct ceph_snap_realm *new)
88 {
89 	struct rb_node **p = &root->rb_node;
90 	struct rb_node *parent = NULL;
91 	struct ceph_snap_realm *r = NULL;
92 
93 	while (*p) {
94 		parent = *p;
95 		r = rb_entry(parent, struct ceph_snap_realm, node);
96 		if (new->ino < r->ino)
97 			p = &(*p)->rb_left;
98 		else if (new->ino > r->ino)
99 			p = &(*p)->rb_right;
100 		else
101 			BUG();
102 	}
103 
104 	rb_link_node(&new->node, parent, p);
105 	rb_insert_color(&new->node, root);
106 }
107 
108 /*
109  * create and get the realm rooted at @ino and bump its ref count.
110  *
111  * caller must hold snap_rwsem for write.
112  */
ceph_create_snap_realm(struct ceph_mds_client * mdsc,u64 ino)113 static struct ceph_snap_realm *ceph_create_snap_realm(
114 	struct ceph_mds_client *mdsc,
115 	u64 ino)
116 {
117 	struct ceph_snap_realm *realm;
118 
119 	lockdep_assert_held_write(&mdsc->snap_rwsem);
120 
121 	realm = kzalloc(sizeof(*realm), GFP_NOFS);
122 	if (!realm)
123 		return ERR_PTR(-ENOMEM);
124 
125 	/* Do not release the global dummy snaprealm until unmouting */
126 	if (ino == CEPH_INO_GLOBAL_SNAPREALM)
127 		atomic_set(&realm->nref, 2);
128 	else
129 		atomic_set(&realm->nref, 1);
130 	realm->ino = ino;
131 	INIT_LIST_HEAD(&realm->children);
132 	INIT_LIST_HEAD(&realm->child_item);
133 	INIT_LIST_HEAD(&realm->empty_item);
134 	INIT_LIST_HEAD(&realm->dirty_item);
135 	INIT_LIST_HEAD(&realm->rebuild_item);
136 	INIT_LIST_HEAD(&realm->inodes_with_caps);
137 	spin_lock_init(&realm->inodes_with_caps_lock);
138 	__insert_snap_realm(&mdsc->snap_realms, realm);
139 	mdsc->num_snap_realms++;
140 
141 	dout("%s %llx %p\n", __func__, realm->ino, realm);
142 	return realm;
143 }
144 
145 /*
146  * lookup the realm rooted at @ino.
147  *
148  * caller must hold snap_rwsem.
149  */
__lookup_snap_realm(struct ceph_mds_client * mdsc,u64 ino)150 static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
151 						   u64 ino)
152 {
153 	struct rb_node *n = mdsc->snap_realms.rb_node;
154 	struct ceph_snap_realm *r;
155 
156 	lockdep_assert_held(&mdsc->snap_rwsem);
157 
158 	while (n) {
159 		r = rb_entry(n, struct ceph_snap_realm, node);
160 		if (ino < r->ino)
161 			n = n->rb_left;
162 		else if (ino > r->ino)
163 			n = n->rb_right;
164 		else {
165 			dout("%s %llx %p\n", __func__, r->ino, r);
166 			return r;
167 		}
168 	}
169 	return NULL;
170 }
171 
ceph_lookup_snap_realm(struct ceph_mds_client * mdsc,u64 ino)172 struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
173 					       u64 ino)
174 {
175 	struct ceph_snap_realm *r;
176 	r = __lookup_snap_realm(mdsc, ino);
177 	if (r)
178 		ceph_get_snap_realm(mdsc, r);
179 	return r;
180 }
181 
182 static void __put_snap_realm(struct ceph_mds_client *mdsc,
183 			     struct ceph_snap_realm *realm);
184 
185 /*
186  * called with snap_rwsem (write)
187  */
__destroy_snap_realm(struct ceph_mds_client * mdsc,struct ceph_snap_realm * realm)188 static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
189 				 struct ceph_snap_realm *realm)
190 {
191 	lockdep_assert_held_write(&mdsc->snap_rwsem);
192 
193 	dout("%s %p %llx\n", __func__, realm, realm->ino);
194 
195 	rb_erase(&realm->node, &mdsc->snap_realms);
196 	mdsc->num_snap_realms--;
197 
198 	if (realm->parent) {
199 		list_del_init(&realm->child_item);
200 		__put_snap_realm(mdsc, realm->parent);
201 	}
202 
203 	kfree(realm->prior_parent_snaps);
204 	kfree(realm->snaps);
205 	ceph_put_snap_context(realm->cached_context);
206 	kfree(realm);
207 }
208 
209 /*
210  * caller holds snap_rwsem (write)
211  */
__put_snap_realm(struct ceph_mds_client * mdsc,struct ceph_snap_realm * realm)212 static void __put_snap_realm(struct ceph_mds_client *mdsc,
213 			     struct ceph_snap_realm *realm)
214 {
215 	lockdep_assert_held_write(&mdsc->snap_rwsem);
216 
217 	/*
218 	 * We do not require the snap_empty_lock here, as any caller that
219 	 * increments the value must hold the snap_rwsem.
220 	 */
221 	if (atomic_dec_and_test(&realm->nref))
222 		__destroy_snap_realm(mdsc, realm);
223 }
224 
225 /*
226  * See comments in ceph_get_snap_realm. Caller needn't hold any locks.
227  */
ceph_put_snap_realm(struct ceph_mds_client * mdsc,struct ceph_snap_realm * realm)228 void ceph_put_snap_realm(struct ceph_mds_client *mdsc,
229 			 struct ceph_snap_realm *realm)
230 {
231 	if (!atomic_dec_and_lock(&realm->nref, &mdsc->snap_empty_lock))
232 		return;
233 
234 	if (down_write_trylock(&mdsc->snap_rwsem)) {
235 		spin_unlock(&mdsc->snap_empty_lock);
236 		__destroy_snap_realm(mdsc, realm);
237 		up_write(&mdsc->snap_rwsem);
238 	} else {
239 		list_add(&realm->empty_item, &mdsc->snap_empty);
240 		spin_unlock(&mdsc->snap_empty_lock);
241 	}
242 }
243 
244 /*
245  * Clean up any realms whose ref counts have dropped to zero.  Note
246  * that this does not include realms who were created but not yet
247  * used.
248  *
249  * Called under snap_rwsem (write)
250  */
__cleanup_empty_realms(struct ceph_mds_client * mdsc)251 static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
252 {
253 	struct ceph_snap_realm *realm;
254 
255 	lockdep_assert_held_write(&mdsc->snap_rwsem);
256 
257 	spin_lock(&mdsc->snap_empty_lock);
258 	while (!list_empty(&mdsc->snap_empty)) {
259 		realm = list_first_entry(&mdsc->snap_empty,
260 				   struct ceph_snap_realm, empty_item);
261 		list_del(&realm->empty_item);
262 		spin_unlock(&mdsc->snap_empty_lock);
263 		__destroy_snap_realm(mdsc, realm);
264 		spin_lock(&mdsc->snap_empty_lock);
265 	}
266 	spin_unlock(&mdsc->snap_empty_lock);
267 }
268 
ceph_cleanup_global_and_empty_realms(struct ceph_mds_client * mdsc)269 void ceph_cleanup_global_and_empty_realms(struct ceph_mds_client *mdsc)
270 {
271 	struct ceph_snap_realm *global_realm;
272 
273 	down_write(&mdsc->snap_rwsem);
274 	global_realm = __lookup_snap_realm(mdsc, CEPH_INO_GLOBAL_SNAPREALM);
275 	if (global_realm)
276 		ceph_put_snap_realm(mdsc, global_realm);
277 	__cleanup_empty_realms(mdsc);
278 	up_write(&mdsc->snap_rwsem);
279 }
280 
281 /*
282  * adjust the parent realm of a given @realm.  adjust child list, and parent
283  * pointers, and ref counts appropriately.
284  *
285  * return true if parent was changed, 0 if unchanged, <0 on error.
286  *
287  * caller must hold snap_rwsem for write.
288  */
adjust_snap_realm_parent(struct ceph_mds_client * mdsc,struct ceph_snap_realm * realm,u64 parentino)289 static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
290 				    struct ceph_snap_realm *realm,
291 				    u64 parentino)
292 {
293 	struct ceph_snap_realm *parent;
294 
295 	lockdep_assert_held_write(&mdsc->snap_rwsem);
296 
297 	if (realm->parent_ino == parentino)
298 		return 0;
299 
300 	parent = ceph_lookup_snap_realm(mdsc, parentino);
301 	if (!parent) {
302 		parent = ceph_create_snap_realm(mdsc, parentino);
303 		if (IS_ERR(parent))
304 			return PTR_ERR(parent);
305 	}
306 	dout("%s %llx %p: %llx %p -> %llx %p\n", __func__, realm->ino,
307 	     realm, realm->parent_ino, realm->parent, parentino, parent);
308 	if (realm->parent) {
309 		list_del_init(&realm->child_item);
310 		ceph_put_snap_realm(mdsc, realm->parent);
311 	}
312 	realm->parent_ino = parentino;
313 	realm->parent = parent;
314 	list_add(&realm->child_item, &parent->children);
315 	return 1;
316 }
317 
318 
cmpu64_rev(const void * a,const void * b)319 static int cmpu64_rev(const void *a, const void *b)
320 {
321 	if (*(u64 *)a < *(u64 *)b)
322 		return 1;
323 	if (*(u64 *)a > *(u64 *)b)
324 		return -1;
325 	return 0;
326 }
327 
328 
329 /*
330  * build the snap context for a given realm.
331  */
build_snap_context(struct ceph_snap_realm * realm,struct list_head * realm_queue,struct list_head * dirty_realms)332 static int build_snap_context(struct ceph_snap_realm *realm,
333 			      struct list_head *realm_queue,
334 			      struct list_head *dirty_realms)
335 {
336 	struct ceph_snap_realm *parent = realm->parent;
337 	struct ceph_snap_context *snapc;
338 	int err = 0;
339 	u32 num = realm->num_prior_parent_snaps + realm->num_snaps;
340 
341 	/*
342 	 * build parent context, if it hasn't been built.
343 	 * conservatively estimate that all parent snaps might be
344 	 * included by us.
345 	 */
346 	if (parent) {
347 		if (!parent->cached_context) {
348 			/* add to the queue head */
349 			list_add(&parent->rebuild_item, realm_queue);
350 			return 1;
351 		}
352 		num += parent->cached_context->num_snaps;
353 	}
354 
355 	/* do i actually need to update?  not if my context seq
356 	   matches realm seq, and my parents' does to.  (this works
357 	   because we rebuild_snap_realms() works _downward_ in
358 	   hierarchy after each update.) */
359 	if (realm->cached_context &&
360 	    realm->cached_context->seq == realm->seq &&
361 	    (!parent ||
362 	     realm->cached_context->seq >= parent->cached_context->seq)) {
363 		dout("%s %llx %p: %p seq %lld (%u snaps) (unchanged)\n",
364 		     __func__, realm->ino, realm, realm->cached_context,
365 		     realm->cached_context->seq,
366 		     (unsigned int)realm->cached_context->num_snaps);
367 		return 0;
368 	}
369 
370 	/* alloc new snap context */
371 	err = -ENOMEM;
372 	if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64))
373 		goto fail;
374 	snapc = ceph_create_snap_context(num, GFP_NOFS);
375 	if (!snapc)
376 		goto fail;
377 
378 	/* build (reverse sorted) snap vector */
379 	num = 0;
380 	snapc->seq = realm->seq;
381 	if (parent) {
382 		u32 i;
383 
384 		/* include any of parent's snaps occurring _after_ my
385 		   parent became my parent */
386 		for (i = 0; i < parent->cached_context->num_snaps; i++)
387 			if (parent->cached_context->snaps[i] >=
388 			    realm->parent_since)
389 				snapc->snaps[num++] =
390 					parent->cached_context->snaps[i];
391 		if (parent->cached_context->seq > snapc->seq)
392 			snapc->seq = parent->cached_context->seq;
393 	}
394 	memcpy(snapc->snaps + num, realm->snaps,
395 	       sizeof(u64)*realm->num_snaps);
396 	num += realm->num_snaps;
397 	memcpy(snapc->snaps + num, realm->prior_parent_snaps,
398 	       sizeof(u64)*realm->num_prior_parent_snaps);
399 	num += realm->num_prior_parent_snaps;
400 
401 	sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL);
402 	snapc->num_snaps = num;
403 	dout("%s %llx %p: %p seq %lld (%u snaps)\n", __func__, realm->ino,
404 	     realm, snapc, snapc->seq, (unsigned int) snapc->num_snaps);
405 
406 	ceph_put_snap_context(realm->cached_context);
407 	realm->cached_context = snapc;
408 	/* queue realm for cap_snap creation */
409 	list_add_tail(&realm->dirty_item, dirty_realms);
410 	return 0;
411 
412 fail:
413 	/*
414 	 * if we fail, clear old (incorrect) cached_context... hopefully
415 	 * we'll have better luck building it later
416 	 */
417 	if (realm->cached_context) {
418 		ceph_put_snap_context(realm->cached_context);
419 		realm->cached_context = NULL;
420 	}
421 	pr_err("%s %llx %p fail %d\n", __func__, realm->ino, realm, err);
422 	return err;
423 }
424 
425 /*
426  * rebuild snap context for the given realm and all of its children.
427  */
rebuild_snap_realms(struct ceph_snap_realm * realm,struct list_head * dirty_realms)428 static void rebuild_snap_realms(struct ceph_snap_realm *realm,
429 				struct list_head *dirty_realms)
430 {
431 	LIST_HEAD(realm_queue);
432 	int last = 0;
433 	bool skip = false;
434 
435 	list_add_tail(&realm->rebuild_item, &realm_queue);
436 
437 	while (!list_empty(&realm_queue)) {
438 		struct ceph_snap_realm *_realm, *child;
439 
440 		_realm = list_first_entry(&realm_queue,
441 					  struct ceph_snap_realm,
442 					  rebuild_item);
443 
444 		/*
445 		 * If the last building failed dues to memory
446 		 * issue, just empty the realm_queue and return
447 		 * to avoid infinite loop.
448 		 */
449 		if (last < 0) {
450 			list_del_init(&_realm->rebuild_item);
451 			continue;
452 		}
453 
454 		last = build_snap_context(_realm, &realm_queue, dirty_realms);
455 		dout("%s %llx %p, %s\n", __func__, _realm->ino, _realm,
456 		     last > 0 ? "is deferred" : !last ? "succeeded" : "failed");
457 
458 		/* is any child in the list ? */
459 		list_for_each_entry(child, &_realm->children, child_item) {
460 			if (!list_empty(&child->rebuild_item)) {
461 				skip = true;
462 				break;
463 			}
464 		}
465 
466 		if (!skip) {
467 			list_for_each_entry(child, &_realm->children, child_item)
468 				list_add_tail(&child->rebuild_item, &realm_queue);
469 		}
470 
471 		/* last == 1 means need to build parent first */
472 		if (last <= 0)
473 			list_del_init(&_realm->rebuild_item);
474 	}
475 }
476 
477 
478 /*
479  * helper to allocate and decode an array of snapids.  free prior
480  * instance, if any.
481  */
dup_array(u64 ** dst,__le64 * src,u32 num)482 static int dup_array(u64 **dst, __le64 *src, u32 num)
483 {
484 	u32 i;
485 
486 	kfree(*dst);
487 	if (num) {
488 		*dst = kcalloc(num, sizeof(u64), GFP_NOFS);
489 		if (!*dst)
490 			return -ENOMEM;
491 		for (i = 0; i < num; i++)
492 			(*dst)[i] = get_unaligned_le64(src + i);
493 	} else {
494 		*dst = NULL;
495 	}
496 	return 0;
497 }
498 
has_new_snaps(struct ceph_snap_context * o,struct ceph_snap_context * n)499 static bool has_new_snaps(struct ceph_snap_context *o,
500 			  struct ceph_snap_context *n)
501 {
502 	if (n->num_snaps == 0)
503 		return false;
504 	/* snaps are in descending order */
505 	return n->snaps[0] > o->seq;
506 }
507 
508 /*
509  * When a snapshot is applied, the size/mtime inode metadata is queued
510  * in a ceph_cap_snap (one for each snapshot) until writeback
511  * completes and the metadata can be flushed back to the MDS.
512  *
513  * However, if a (sync) write is currently in-progress when we apply
514  * the snapshot, we have to wait until the write succeeds or fails
515  * (and a final size/mtime is known).  In this case the
516  * cap_snap->writing = 1, and is said to be "pending."  When the write
517  * finishes, we __ceph_finish_cap_snap().
518  *
519  * Caller must hold snap_rwsem for read (i.e., the realm topology won't
520  * change).
521  */
ceph_queue_cap_snap(struct ceph_inode_info * ci,struct ceph_cap_snap ** pcapsnap)522 static void ceph_queue_cap_snap(struct ceph_inode_info *ci,
523 				struct ceph_cap_snap **pcapsnap)
524 {
525 	struct inode *inode = &ci->netfs.inode;
526 	struct ceph_snap_context *old_snapc, *new_snapc;
527 	struct ceph_cap_snap *capsnap = *pcapsnap;
528 	struct ceph_buffer *old_blob = NULL;
529 	int used, dirty;
530 
531 	spin_lock(&ci->i_ceph_lock);
532 	used = __ceph_caps_used(ci);
533 	dirty = __ceph_caps_dirty(ci);
534 
535 	old_snapc = ci->i_head_snapc;
536 	new_snapc = ci->i_snap_realm->cached_context;
537 
538 	/*
539 	 * If there is a write in progress, treat that as a dirty Fw,
540 	 * even though it hasn't completed yet; by the time we finish
541 	 * up this capsnap it will be.
542 	 */
543 	if (used & CEPH_CAP_FILE_WR)
544 		dirty |= CEPH_CAP_FILE_WR;
545 
546 	if (__ceph_have_pending_cap_snap(ci)) {
547 		/* there is no point in queuing multiple "pending" cap_snaps,
548 		   as no new writes are allowed to start when pending, so any
549 		   writes in progress now were started before the previous
550 		   cap_snap.  lucky us. */
551 		dout("%s %p %llx.%llx already pending\n",
552 		     __func__, inode, ceph_vinop(inode));
553 		goto update_snapc;
554 	}
555 	if (ci->i_wrbuffer_ref_head == 0 &&
556 	    !(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) {
557 		dout("%s %p %llx.%llx nothing dirty|writing\n",
558 		     __func__, inode, ceph_vinop(inode));
559 		goto update_snapc;
560 	}
561 
562 	BUG_ON(!old_snapc);
563 
564 	/*
565 	 * There is no need to send FLUSHSNAP message to MDS if there is
566 	 * no new snapshot. But when there is dirty pages or on-going
567 	 * writes, we still need to create cap_snap. cap_snap is needed
568 	 * by the write path and page writeback path.
569 	 *
570 	 * also see ceph_try_drop_cap_snap()
571 	 */
572 	if (has_new_snaps(old_snapc, new_snapc)) {
573 		if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))
574 			capsnap->need_flush = true;
575 	} else {
576 		if (!(used & CEPH_CAP_FILE_WR) &&
577 		    ci->i_wrbuffer_ref_head == 0) {
578 			dout("%s %p %llx.%llx no new_snap|dirty_page|writing\n",
579 			     __func__, inode, ceph_vinop(inode));
580 			goto update_snapc;
581 		}
582 	}
583 
584 	dout("%s %p %llx.%llx cap_snap %p queuing under %p %s %s\n",
585 	     __func__, inode, ceph_vinop(inode), capsnap, old_snapc,
586 	     ceph_cap_string(dirty), capsnap->need_flush ? "" : "no_flush");
587 	ihold(inode);
588 
589 	capsnap->follows = old_snapc->seq;
590 	capsnap->issued = __ceph_caps_issued(ci, NULL);
591 	capsnap->dirty = dirty;
592 
593 	capsnap->mode = inode->i_mode;
594 	capsnap->uid = inode->i_uid;
595 	capsnap->gid = inode->i_gid;
596 
597 	if (dirty & CEPH_CAP_XATTR_EXCL) {
598 		old_blob = __ceph_build_xattrs_blob(ci);
599 		capsnap->xattr_blob =
600 			ceph_buffer_get(ci->i_xattrs.blob);
601 		capsnap->xattr_version = ci->i_xattrs.version;
602 	} else {
603 		capsnap->xattr_blob = NULL;
604 		capsnap->xattr_version = 0;
605 	}
606 
607 	capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE;
608 
609 	/* dirty page count moved from _head to this cap_snap;
610 	   all subsequent writes page dirties occur _after_ this
611 	   snapshot. */
612 	capsnap->dirty_pages = ci->i_wrbuffer_ref_head;
613 	ci->i_wrbuffer_ref_head = 0;
614 	capsnap->context = old_snapc;
615 	list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps);
616 
617 	if (used & CEPH_CAP_FILE_WR) {
618 		dout("%s %p %llx.%llx cap_snap %p snapc %p seq %llu used WR,"
619 		     " now pending\n", __func__, inode, ceph_vinop(inode),
620 		     capsnap, old_snapc, old_snapc->seq);
621 		capsnap->writing = 1;
622 	} else {
623 		/* note mtime, size NOW. */
624 		__ceph_finish_cap_snap(ci, capsnap);
625 	}
626 	*pcapsnap = NULL;
627 	old_snapc = NULL;
628 
629 update_snapc:
630 	if (ci->i_wrbuffer_ref_head == 0 &&
631 	    ci->i_wr_ref == 0 &&
632 	    ci->i_dirty_caps == 0 &&
633 	    ci->i_flushing_caps == 0) {
634 		ci->i_head_snapc = NULL;
635 	} else {
636 		ci->i_head_snapc = ceph_get_snap_context(new_snapc);
637 		dout(" new snapc is %p\n", new_snapc);
638 	}
639 	spin_unlock(&ci->i_ceph_lock);
640 
641 	ceph_buffer_put(old_blob);
642 	ceph_put_snap_context(old_snapc);
643 }
644 
645 /*
646  * Finalize the size, mtime for a cap_snap.. that is, settle on final values
647  * to be used for the snapshot, to be flushed back to the mds.
648  *
649  * If capsnap can now be flushed, add to snap_flush list, and return 1.
650  *
651  * Caller must hold i_ceph_lock.
652  */
__ceph_finish_cap_snap(struct ceph_inode_info * ci,struct ceph_cap_snap * capsnap)653 int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
654 			    struct ceph_cap_snap *capsnap)
655 {
656 	struct inode *inode = &ci->netfs.inode;
657 	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
658 
659 	BUG_ON(capsnap->writing);
660 	capsnap->size = i_size_read(inode);
661 	capsnap->mtime = inode->i_mtime;
662 	capsnap->atime = inode->i_atime;
663 	capsnap->ctime = inode_get_ctime(inode);
664 	capsnap->btime = ci->i_btime;
665 	capsnap->change_attr = inode_peek_iversion_raw(inode);
666 	capsnap->time_warp_seq = ci->i_time_warp_seq;
667 	capsnap->truncate_size = ci->i_truncate_size;
668 	capsnap->truncate_seq = ci->i_truncate_seq;
669 	if (capsnap->dirty_pages) {
670 		dout("%s %p %llx.%llx cap_snap %p snapc %p %llu %s s=%llu "
671 		     "still has %d dirty pages\n", __func__, inode,
672 		     ceph_vinop(inode), capsnap, capsnap->context,
673 		     capsnap->context->seq, ceph_cap_string(capsnap->dirty),
674 		     capsnap->size, capsnap->dirty_pages);
675 		return 0;
676 	}
677 
678 	/*
679 	 * Defer flushing the capsnap if the dirty buffer not flushed yet.
680 	 * And trigger to flush the buffer immediately.
681 	 */
682 	if (ci->i_wrbuffer_ref) {
683 		dout("%s %p %llx.%llx cap_snap %p snapc %p %llu %s s=%llu "
684 		     "used WRBUFFER, delaying\n", __func__, inode,
685 		     ceph_vinop(inode), capsnap, capsnap->context,
686 		     capsnap->context->seq, ceph_cap_string(capsnap->dirty),
687 		     capsnap->size);
688 		ceph_queue_writeback(inode);
689 		return 0;
690 	}
691 
692 	ci->i_ceph_flags |= CEPH_I_FLUSH_SNAPS;
693 	dout("%s %p %llx.%llx cap_snap %p snapc %p %llu %s s=%llu\n",
694 	     __func__, inode, ceph_vinop(inode), capsnap, capsnap->context,
695 	     capsnap->context->seq, ceph_cap_string(capsnap->dirty),
696 	     capsnap->size);
697 
698 	spin_lock(&mdsc->snap_flush_lock);
699 	if (list_empty(&ci->i_snap_flush_item)) {
700 		ihold(inode);
701 		list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
702 	}
703 	spin_unlock(&mdsc->snap_flush_lock);
704 	return 1;  /* caller may want to ceph_flush_snaps */
705 }
706 
707 /*
708  * Queue cap_snaps for snap writeback for this realm and its children.
709  * Called under snap_rwsem, so realm topology won't change.
710  */
queue_realm_cap_snaps(struct ceph_snap_realm * realm)711 static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
712 {
713 	struct ceph_inode_info *ci;
714 	struct inode *lastinode = NULL;
715 	struct ceph_cap_snap *capsnap = NULL;
716 
717 	dout("%s %p %llx inode\n", __func__, realm, realm->ino);
718 
719 	spin_lock(&realm->inodes_with_caps_lock);
720 	list_for_each_entry(ci, &realm->inodes_with_caps, i_snap_realm_item) {
721 		struct inode *inode = igrab(&ci->netfs.inode);
722 		if (!inode)
723 			continue;
724 		spin_unlock(&realm->inodes_with_caps_lock);
725 		iput(lastinode);
726 		lastinode = inode;
727 
728 		/*
729 		 * Allocate the capsnap memory outside of ceph_queue_cap_snap()
730 		 * to reduce very possible but unnecessary frequently memory
731 		 * allocate/free in this loop.
732 		 */
733 		if (!capsnap) {
734 			capsnap = kmem_cache_zalloc(ceph_cap_snap_cachep, GFP_NOFS);
735 			if (!capsnap) {
736 				pr_err("ENOMEM allocating ceph_cap_snap on %p\n",
737 				       inode);
738 				return;
739 			}
740 		}
741 		capsnap->cap_flush.is_capsnap = true;
742 		refcount_set(&capsnap->nref, 1);
743 		INIT_LIST_HEAD(&capsnap->cap_flush.i_list);
744 		INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
745 		INIT_LIST_HEAD(&capsnap->ci_item);
746 
747 		ceph_queue_cap_snap(ci, &capsnap);
748 		spin_lock(&realm->inodes_with_caps_lock);
749 	}
750 	spin_unlock(&realm->inodes_with_caps_lock);
751 	iput(lastinode);
752 
753 	if (capsnap)
754 		kmem_cache_free(ceph_cap_snap_cachep, capsnap);
755 	dout("%s %p %llx done\n", __func__, realm, realm->ino);
756 }
757 
758 /*
759  * Parse and apply a snapblob "snap trace" from the MDS.  This specifies
760  * the snap realm parameters from a given realm and all of its ancestors,
761  * up to the root.
762  *
763  * Caller must hold snap_rwsem for write.
764  */
ceph_update_snap_trace(struct ceph_mds_client * mdsc,void * p,void * e,bool deletion,struct ceph_snap_realm ** realm_ret)765 int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
766 			   void *p, void *e, bool deletion,
767 			   struct ceph_snap_realm **realm_ret)
768 {
769 	struct ceph_mds_snap_realm *ri;    /* encoded */
770 	__le64 *snaps;                     /* encoded */
771 	__le64 *prior_parent_snaps;        /* encoded */
772 	struct ceph_snap_realm *realm;
773 	struct ceph_snap_realm *first_realm = NULL;
774 	struct ceph_snap_realm *realm_to_rebuild = NULL;
775 	struct ceph_client *client = mdsc->fsc->client;
776 	int rebuild_snapcs;
777 	int err = -ENOMEM;
778 	int ret;
779 	LIST_HEAD(dirty_realms);
780 
781 	lockdep_assert_held_write(&mdsc->snap_rwsem);
782 
783 	dout("%s deletion=%d\n", __func__, deletion);
784 more:
785 	realm = NULL;
786 	rebuild_snapcs = 0;
787 	ceph_decode_need(&p, e, sizeof(*ri), bad);
788 	ri = p;
789 	p += sizeof(*ri);
790 	ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) +
791 			    le32_to_cpu(ri->num_prior_parent_snaps)), bad);
792 	snaps = p;
793 	p += sizeof(u64) * le32_to_cpu(ri->num_snaps);
794 	prior_parent_snaps = p;
795 	p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps);
796 
797 	realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino));
798 	if (!realm) {
799 		realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino));
800 		if (IS_ERR(realm)) {
801 			err = PTR_ERR(realm);
802 			goto fail;
803 		}
804 	}
805 
806 	/* ensure the parent is correct */
807 	err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent));
808 	if (err < 0)
809 		goto fail;
810 	rebuild_snapcs += err;
811 
812 	if (le64_to_cpu(ri->seq) > realm->seq) {
813 		dout("%s updating %llx %p %lld -> %lld\n", __func__,
814 		     realm->ino, realm, realm->seq, le64_to_cpu(ri->seq));
815 		/* update realm parameters, snap lists */
816 		realm->seq = le64_to_cpu(ri->seq);
817 		realm->created = le64_to_cpu(ri->created);
818 		realm->parent_since = le64_to_cpu(ri->parent_since);
819 
820 		realm->num_snaps = le32_to_cpu(ri->num_snaps);
821 		err = dup_array(&realm->snaps, snaps, realm->num_snaps);
822 		if (err < 0)
823 			goto fail;
824 
825 		realm->num_prior_parent_snaps =
826 			le32_to_cpu(ri->num_prior_parent_snaps);
827 		err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps,
828 				realm->num_prior_parent_snaps);
829 		if (err < 0)
830 			goto fail;
831 
832 		if (realm->seq > mdsc->last_snap_seq)
833 			mdsc->last_snap_seq = realm->seq;
834 
835 		rebuild_snapcs = 1;
836 	} else if (!realm->cached_context) {
837 		dout("%s %llx %p seq %lld new\n", __func__,
838 		     realm->ino, realm, realm->seq);
839 		rebuild_snapcs = 1;
840 	} else {
841 		dout("%s %llx %p seq %lld unchanged\n", __func__,
842 		     realm->ino, realm, realm->seq);
843 	}
844 
845 	dout("done with %llx %p, rebuild_snapcs=%d, %p %p\n", realm->ino,
846 	     realm, rebuild_snapcs, p, e);
847 
848 	/*
849 	 * this will always track the uppest parent realm from which
850 	 * we need to rebuild the snapshot contexts _downward_ in
851 	 * hierarchy.
852 	 */
853 	if (rebuild_snapcs)
854 		realm_to_rebuild = realm;
855 
856 	/* rebuild_snapcs when we reach the _end_ (root) of the trace */
857 	if (realm_to_rebuild && p >= e)
858 		rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
859 
860 	if (!first_realm)
861 		first_realm = realm;
862 	else
863 		ceph_put_snap_realm(mdsc, realm);
864 
865 	if (p < e)
866 		goto more;
867 
868 	/*
869 	 * queue cap snaps _after_ we've built the new snap contexts,
870 	 * so that i_head_snapc can be set appropriately.
871 	 */
872 	while (!list_empty(&dirty_realms)) {
873 		realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
874 					 dirty_item);
875 		list_del_init(&realm->dirty_item);
876 		queue_realm_cap_snaps(realm);
877 	}
878 
879 	if (realm_ret)
880 		*realm_ret = first_realm;
881 	else
882 		ceph_put_snap_realm(mdsc, first_realm);
883 
884 	__cleanup_empty_realms(mdsc);
885 	return 0;
886 
887 bad:
888 	err = -EIO;
889 fail:
890 	if (realm && !IS_ERR(realm))
891 		ceph_put_snap_realm(mdsc, realm);
892 	if (first_realm)
893 		ceph_put_snap_realm(mdsc, first_realm);
894 	pr_err("%s error %d\n", __func__, err);
895 
896 	/*
897 	 * When receiving a corrupted snap trace we don't know what
898 	 * exactly has happened in MDS side. And we shouldn't continue
899 	 * writing to OSD, which may corrupt the snapshot contents.
900 	 *
901 	 * Just try to blocklist this kclient and then this kclient
902 	 * must be remounted to continue after the corrupted metadata
903 	 * fixed in the MDS side.
904 	 */
905 	WRITE_ONCE(mdsc->fsc->mount_state, CEPH_MOUNT_FENCE_IO);
906 	ret = ceph_monc_blocklist_add(&client->monc, &client->msgr.inst.addr);
907 	if (ret)
908 		pr_err("%s failed to blocklist %s: %d\n", __func__,
909 		       ceph_pr_addr(&client->msgr.inst.addr), ret);
910 
911 	WARN(1, "%s: %s%sdo remount to continue%s",
912 	     __func__, ret ? "" : ceph_pr_addr(&client->msgr.inst.addr),
913 	     ret ? "" : " was blocklisted, ",
914 	     err == -EIO ? " after corrupted snaptrace is fixed" : "");
915 
916 	return err;
917 }
918 
919 
920 /*
921  * Send any cap_snaps that are queued for flush.  Try to carry
922  * s_mutex across multiple snap flushes to avoid locking overhead.
923  *
924  * Caller holds no locks.
925  */
flush_snaps(struct ceph_mds_client * mdsc)926 static void flush_snaps(struct ceph_mds_client *mdsc)
927 {
928 	struct ceph_inode_info *ci;
929 	struct inode *inode;
930 	struct ceph_mds_session *session = NULL;
931 
932 	dout("%s\n", __func__);
933 	spin_lock(&mdsc->snap_flush_lock);
934 	while (!list_empty(&mdsc->snap_flush_list)) {
935 		ci = list_first_entry(&mdsc->snap_flush_list,
936 				struct ceph_inode_info, i_snap_flush_item);
937 		inode = &ci->netfs.inode;
938 		ihold(inode);
939 		spin_unlock(&mdsc->snap_flush_lock);
940 		ceph_flush_snaps(ci, &session);
941 		iput(inode);
942 		spin_lock(&mdsc->snap_flush_lock);
943 	}
944 	spin_unlock(&mdsc->snap_flush_lock);
945 
946 	ceph_put_mds_session(session);
947 	dout("%s done\n", __func__);
948 }
949 
950 /**
951  * ceph_change_snap_realm - change the snap_realm for an inode
952  * @inode: inode to move to new snap realm
953  * @realm: new realm to move inode into (may be NULL)
954  *
955  * Detach an inode from its old snaprealm (if any) and attach it to
956  * the new snaprealm (if any). The old snap realm reference held by
957  * the inode is put. If realm is non-NULL, then the caller's reference
958  * to it is taken over by the inode.
959  */
ceph_change_snap_realm(struct inode * inode,struct ceph_snap_realm * realm)960 void ceph_change_snap_realm(struct inode *inode, struct ceph_snap_realm *realm)
961 {
962 	struct ceph_inode_info *ci = ceph_inode(inode);
963 	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
964 	struct ceph_snap_realm *oldrealm = ci->i_snap_realm;
965 
966 	lockdep_assert_held(&ci->i_ceph_lock);
967 
968 	if (oldrealm) {
969 		spin_lock(&oldrealm->inodes_with_caps_lock);
970 		list_del_init(&ci->i_snap_realm_item);
971 		if (oldrealm->ino == ci->i_vino.ino)
972 			oldrealm->inode = NULL;
973 		spin_unlock(&oldrealm->inodes_with_caps_lock);
974 		ceph_put_snap_realm(mdsc, oldrealm);
975 	}
976 
977 	ci->i_snap_realm = realm;
978 
979 	if (realm) {
980 		spin_lock(&realm->inodes_with_caps_lock);
981 		list_add(&ci->i_snap_realm_item, &realm->inodes_with_caps);
982 		if (realm->ino == ci->i_vino.ino)
983 			realm->inode = inode;
984 		spin_unlock(&realm->inodes_with_caps_lock);
985 	}
986 }
987 
988 /*
989  * Handle a snap notification from the MDS.
990  *
991  * This can take two basic forms: the simplest is just a snap creation
992  * or deletion notification on an existing realm.  This should update the
993  * realm and its children.
994  *
995  * The more difficult case is realm creation, due to snap creation at a
996  * new point in the file hierarchy, or due to a rename that moves a file or
997  * directory into another realm.
998  */
ceph_handle_snap(struct ceph_mds_client * mdsc,struct ceph_mds_session * session,struct ceph_msg * msg)999 void ceph_handle_snap(struct ceph_mds_client *mdsc,
1000 		      struct ceph_mds_session *session,
1001 		      struct ceph_msg *msg)
1002 {
1003 	struct super_block *sb = mdsc->fsc->sb;
1004 	int mds = session->s_mds;
1005 	u64 split;
1006 	int op;
1007 	int trace_len;
1008 	struct ceph_snap_realm *realm = NULL;
1009 	void *p = msg->front.iov_base;
1010 	void *e = p + msg->front.iov_len;
1011 	struct ceph_mds_snap_head *h;
1012 	int num_split_inos, num_split_realms;
1013 	__le64 *split_inos = NULL, *split_realms = NULL;
1014 	int i;
1015 	int locked_rwsem = 0;
1016 	bool close_sessions = false;
1017 
1018 	if (!ceph_inc_mds_stopping_blocker(mdsc, session))
1019 		return;
1020 
1021 	/* decode */
1022 	if (msg->front.iov_len < sizeof(*h))
1023 		goto bad;
1024 	h = p;
1025 	op = le32_to_cpu(h->op);
1026 	split = le64_to_cpu(h->split);   /* non-zero if we are splitting an
1027 					  * existing realm */
1028 	num_split_inos = le32_to_cpu(h->num_split_inos);
1029 	num_split_realms = le32_to_cpu(h->num_split_realms);
1030 	trace_len = le32_to_cpu(h->trace_len);
1031 	p += sizeof(*h);
1032 
1033 	dout("%s from mds%d op %s split %llx tracelen %d\n", __func__,
1034 	     mds, ceph_snap_op_name(op), split, trace_len);
1035 
1036 	down_write(&mdsc->snap_rwsem);
1037 	locked_rwsem = 1;
1038 
1039 	if (op == CEPH_SNAP_OP_SPLIT) {
1040 		struct ceph_mds_snap_realm *ri;
1041 
1042 		/*
1043 		 * A "split" breaks part of an existing realm off into
1044 		 * a new realm.  The MDS provides a list of inodes
1045 		 * (with caps) and child realms that belong to the new
1046 		 * child.
1047 		 */
1048 		split_inos = p;
1049 		p += sizeof(u64) * num_split_inos;
1050 		split_realms = p;
1051 		p += sizeof(u64) * num_split_realms;
1052 		ceph_decode_need(&p, e, sizeof(*ri), bad);
1053 		/* we will peek at realm info here, but will _not_
1054 		 * advance p, as the realm update will occur below in
1055 		 * ceph_update_snap_trace. */
1056 		ri = p;
1057 
1058 		realm = ceph_lookup_snap_realm(mdsc, split);
1059 		if (!realm) {
1060 			realm = ceph_create_snap_realm(mdsc, split);
1061 			if (IS_ERR(realm))
1062 				goto out;
1063 		}
1064 
1065 		dout("splitting snap_realm %llx %p\n", realm->ino, realm);
1066 		for (i = 0; i < num_split_inos; i++) {
1067 			struct ceph_vino vino = {
1068 				.ino = le64_to_cpu(split_inos[i]),
1069 				.snap = CEPH_NOSNAP,
1070 			};
1071 			struct inode *inode = ceph_find_inode(sb, vino);
1072 			struct ceph_inode_info *ci;
1073 
1074 			if (!inode)
1075 				continue;
1076 			ci = ceph_inode(inode);
1077 
1078 			spin_lock(&ci->i_ceph_lock);
1079 			if (!ci->i_snap_realm)
1080 				goto skip_inode;
1081 			/*
1082 			 * If this inode belongs to a realm that was
1083 			 * created after our new realm, we experienced
1084 			 * a race (due to another split notifications
1085 			 * arriving from a different MDS).  So skip
1086 			 * this inode.
1087 			 */
1088 			if (ci->i_snap_realm->created >
1089 			    le64_to_cpu(ri->created)) {
1090 				dout(" leaving %p %llx.%llx in newer realm %llx %p\n",
1091 				     inode, ceph_vinop(inode), ci->i_snap_realm->ino,
1092 				     ci->i_snap_realm);
1093 				goto skip_inode;
1094 			}
1095 			dout(" will move %p %llx.%llx to split realm %llx %p\n",
1096 			     inode, ceph_vinop(inode), realm->ino, realm);
1097 
1098 			ceph_get_snap_realm(mdsc, realm);
1099 			ceph_change_snap_realm(inode, realm);
1100 			spin_unlock(&ci->i_ceph_lock);
1101 			iput(inode);
1102 			continue;
1103 
1104 skip_inode:
1105 			spin_unlock(&ci->i_ceph_lock);
1106 			iput(inode);
1107 		}
1108 
1109 		/* we may have taken some of the old realm's children. */
1110 		for (i = 0; i < num_split_realms; i++) {
1111 			struct ceph_snap_realm *child =
1112 				__lookup_snap_realm(mdsc,
1113 					   le64_to_cpu(split_realms[i]));
1114 			if (!child)
1115 				continue;
1116 			adjust_snap_realm_parent(mdsc, child, realm->ino);
1117 		}
1118 	} else {
1119 		/*
1120 		 * In the non-split case both 'num_split_inos' and
1121 		 * 'num_split_realms' should be 0, making this a no-op.
1122 		 * However the MDS happens to populate 'split_realms' list
1123 		 * in one of the UPDATE op cases by mistake.
1124 		 *
1125 		 * Skip both lists just in case to ensure that 'p' is
1126 		 * positioned at the start of realm info, as expected by
1127 		 * ceph_update_snap_trace().
1128 		 */
1129 		p += sizeof(u64) * num_split_inos;
1130 		p += sizeof(u64) * num_split_realms;
1131 	}
1132 
1133 	/*
1134 	 * update using the provided snap trace. if we are deleting a
1135 	 * snap, we can avoid queueing cap_snaps.
1136 	 */
1137 	if (ceph_update_snap_trace(mdsc, p, e,
1138 				   op == CEPH_SNAP_OP_DESTROY,
1139 				   NULL)) {
1140 		close_sessions = true;
1141 		goto bad;
1142 	}
1143 
1144 	if (op == CEPH_SNAP_OP_SPLIT)
1145 		/* we took a reference when we created the realm, above */
1146 		ceph_put_snap_realm(mdsc, realm);
1147 
1148 	__cleanup_empty_realms(mdsc);
1149 
1150 	up_write(&mdsc->snap_rwsem);
1151 
1152 	flush_snaps(mdsc);
1153 	ceph_dec_mds_stopping_blocker(mdsc);
1154 	return;
1155 
1156 bad:
1157 	pr_err("%s corrupt snap message from mds%d\n", __func__, mds);
1158 	ceph_msg_dump(msg);
1159 out:
1160 	if (locked_rwsem)
1161 		up_write(&mdsc->snap_rwsem);
1162 
1163 	ceph_dec_mds_stopping_blocker(mdsc);
1164 
1165 	if (close_sessions)
1166 		ceph_mdsc_close_sessions(mdsc);
1167 	return;
1168 }
1169 
ceph_get_snapid_map(struct ceph_mds_client * mdsc,u64 snap)1170 struct ceph_snapid_map* ceph_get_snapid_map(struct ceph_mds_client *mdsc,
1171 					    u64 snap)
1172 {
1173 	struct ceph_snapid_map *sm, *exist;
1174 	struct rb_node **p, *parent;
1175 	int ret;
1176 
1177 	exist = NULL;
1178 	spin_lock(&mdsc->snapid_map_lock);
1179 	p = &mdsc->snapid_map_tree.rb_node;
1180 	while (*p) {
1181 		exist = rb_entry(*p, struct ceph_snapid_map, node);
1182 		if (snap > exist->snap) {
1183 			p = &(*p)->rb_left;
1184 		} else if (snap < exist->snap) {
1185 			p = &(*p)->rb_right;
1186 		} else {
1187 			if (atomic_inc_return(&exist->ref) == 1)
1188 				list_del_init(&exist->lru);
1189 			break;
1190 		}
1191 		exist = NULL;
1192 	}
1193 	spin_unlock(&mdsc->snapid_map_lock);
1194 	if (exist) {
1195 		dout("%s found snapid map %llx -> %x\n", __func__,
1196 		     exist->snap, exist->dev);
1197 		return exist;
1198 	}
1199 
1200 	sm = kmalloc(sizeof(*sm), GFP_NOFS);
1201 	if (!sm)
1202 		return NULL;
1203 
1204 	ret = get_anon_bdev(&sm->dev);
1205 	if (ret < 0) {
1206 		kfree(sm);
1207 		return NULL;
1208 	}
1209 
1210 	INIT_LIST_HEAD(&sm->lru);
1211 	atomic_set(&sm->ref, 1);
1212 	sm->snap = snap;
1213 
1214 	exist = NULL;
1215 	parent = NULL;
1216 	p = &mdsc->snapid_map_tree.rb_node;
1217 	spin_lock(&mdsc->snapid_map_lock);
1218 	while (*p) {
1219 		parent = *p;
1220 		exist = rb_entry(*p, struct ceph_snapid_map, node);
1221 		if (snap > exist->snap)
1222 			p = &(*p)->rb_left;
1223 		else if (snap < exist->snap)
1224 			p = &(*p)->rb_right;
1225 		else
1226 			break;
1227 		exist = NULL;
1228 	}
1229 	if (exist) {
1230 		if (atomic_inc_return(&exist->ref) == 1)
1231 			list_del_init(&exist->lru);
1232 	} else {
1233 		rb_link_node(&sm->node, parent, p);
1234 		rb_insert_color(&sm->node, &mdsc->snapid_map_tree);
1235 	}
1236 	spin_unlock(&mdsc->snapid_map_lock);
1237 	if (exist) {
1238 		free_anon_bdev(sm->dev);
1239 		kfree(sm);
1240 		dout("%s found snapid map %llx -> %x\n", __func__,
1241 		     exist->snap, exist->dev);
1242 		return exist;
1243 	}
1244 
1245 	dout("%s create snapid map %llx -> %x\n", __func__,
1246 	     sm->snap, sm->dev);
1247 	return sm;
1248 }
1249 
ceph_put_snapid_map(struct ceph_mds_client * mdsc,struct ceph_snapid_map * sm)1250 void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
1251 			 struct ceph_snapid_map *sm)
1252 {
1253 	if (!sm)
1254 		return;
1255 	if (atomic_dec_and_lock(&sm->ref, &mdsc->snapid_map_lock)) {
1256 		if (!RB_EMPTY_NODE(&sm->node)) {
1257 			sm->last_used = jiffies;
1258 			list_add_tail(&sm->lru, &mdsc->snapid_map_lru);
1259 			spin_unlock(&mdsc->snapid_map_lock);
1260 		} else {
1261 			/* already cleaned up by
1262 			 * ceph_cleanup_snapid_map() */
1263 			spin_unlock(&mdsc->snapid_map_lock);
1264 			kfree(sm);
1265 		}
1266 	}
1267 }
1268 
ceph_trim_snapid_map(struct ceph_mds_client * mdsc)1269 void ceph_trim_snapid_map(struct ceph_mds_client *mdsc)
1270 {
1271 	struct ceph_snapid_map *sm;
1272 	unsigned long now;
1273 	LIST_HEAD(to_free);
1274 
1275 	spin_lock(&mdsc->snapid_map_lock);
1276 	now = jiffies;
1277 
1278 	while (!list_empty(&mdsc->snapid_map_lru)) {
1279 		sm = list_first_entry(&mdsc->snapid_map_lru,
1280 				      struct ceph_snapid_map, lru);
1281 		if (time_after(sm->last_used + CEPH_SNAPID_MAP_TIMEOUT, now))
1282 			break;
1283 
1284 		rb_erase(&sm->node, &mdsc->snapid_map_tree);
1285 		list_move(&sm->lru, &to_free);
1286 	}
1287 	spin_unlock(&mdsc->snapid_map_lock);
1288 
1289 	while (!list_empty(&to_free)) {
1290 		sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
1291 		list_del(&sm->lru);
1292 		dout("trim snapid map %llx -> %x\n", sm->snap, sm->dev);
1293 		free_anon_bdev(sm->dev);
1294 		kfree(sm);
1295 	}
1296 }
1297 
ceph_cleanup_snapid_map(struct ceph_mds_client * mdsc)1298 void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
1299 {
1300 	struct ceph_snapid_map *sm;
1301 	struct rb_node *p;
1302 	LIST_HEAD(to_free);
1303 
1304 	spin_lock(&mdsc->snapid_map_lock);
1305 	while ((p = rb_first(&mdsc->snapid_map_tree))) {
1306 		sm = rb_entry(p, struct ceph_snapid_map, node);
1307 		rb_erase(p, &mdsc->snapid_map_tree);
1308 		RB_CLEAR_NODE(p);
1309 		list_move(&sm->lru, &to_free);
1310 	}
1311 	spin_unlock(&mdsc->snapid_map_lock);
1312 
1313 	while (!list_empty(&to_free)) {
1314 		sm = list_first_entry(&to_free, struct ceph_snapid_map, lru);
1315 		list_del(&sm->lru);
1316 		free_anon_bdev(sm->dev);
1317 		if (WARN_ON_ONCE(atomic_read(&sm->ref))) {
1318 			pr_err("snapid map %llx -> %x still in use\n",
1319 			       sm->snap, sm->dev);
1320 		}
1321 		kfree(sm);
1322 	}
1323 }
1324