fs/ceph/snap.c

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

DEFINITIONS
