| #include <linux/ceph/ceph_debug.h> |
| |
| #include <linux/sort.h> |
| #include <linux/slab.h> |
| |
| #include "super.h" |
| #include "mds_client.h" |
| |
| #include <linux/ceph/decode.h> |
| |
| /* |
| * Snapshots in ceph are driven in large part by cooperation from the |
| * client. In contrast to local file systems or file servers that |
| * implement snapshots at a single point in the system, ceph's |
| * distributed access to storage requires clients to help decide |
| * whether a write logically occurs before or after a recently created |
| * snapshot. |
| * |
| * This provides a perfect instantanous client-wide snapshot. Between |
| * clients, however, snapshots may appear to be applied at slightly |
| * different points in time, depending on delays in delivering the |
| * snapshot notification. |
| * |
| * Snapshots are _not_ file system-wide. Instead, each snapshot |
| * applies to the subdirectory nested beneath some directory. This |
| * effectively divides the hierarchy into multiple "realms," where all |
| * of the files contained by each realm share the same set of |
| * snapshots. An individual realm's snap set contains snapshots |
| * explicitly created on that realm, as well as any snaps in its |
| * parent's snap set _after_ the point at which the parent became it's |
| * parent (due to, say, a rename). Similarly, snaps from prior parents |
| * during the time intervals during which they were the parent are included. |
| * |
| * The client is spared most of this detail, fortunately... it must only |
| * maintains a hierarchy of realms reflecting the current parent/child |
| * realm relationship, and for each realm has an explicit list of snaps |
| * inherited from prior parents. |
| * |
| * A snap_realm struct is maintained for realms containing every inode |
| * with an open cap in the system. (The needed snap realm information is |
| * provided by the MDS whenever a cap is issued, i.e., on open.) A 'seq' |
| * version number is used to ensure that as realm parameters change (new |
| * snapshot, new parent, etc.) the client's realm hierarchy is updated. |
| * |
| * The realm hierarchy drives the generation of a 'snap context' for each |
| * realm, which simply lists the resulting set of snaps for the realm. This |
| * is attached to any writes sent to OSDs. |
| */ |
| /* |
| * Unfortunately error handling is a bit mixed here. If we get a snap |
| * update, but don't have enough memory to update our realm hierarchy, |
| * it's not clear what we can do about it (besides complaining to the |
| * console). |
| */ |
| |
| |
| /* |
| * increase ref count for the realm |
| * |
| * caller must hold snap_rwsem for write. |
| */ |
| void ceph_get_snap_realm(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm) |
| { |
| dout("get_realm %p %d -> %d\n", realm, |
| atomic_read(&realm->nref), atomic_read(&realm->nref)+1); |
| /* |
| * since we _only_ increment realm refs or empty the empty |
| * list with snap_rwsem held, adjusting the empty list here is |
| * safe. we do need to protect against concurrent empty list |
| * additions, however. |
| */ |
| if (atomic_inc_return(&realm->nref) == 1) { |
| spin_lock(&mdsc->snap_empty_lock); |
| list_del_init(&realm->empty_item); |
| spin_unlock(&mdsc->snap_empty_lock); |
| } |
| } |
| |
| static void __insert_snap_realm(struct rb_root *root, |
| struct ceph_snap_realm *new) |
| { |
| struct rb_node **p = &root->rb_node; |
| struct rb_node *parent = NULL; |
| struct ceph_snap_realm *r = NULL; |
| |
| while (*p) { |
| parent = *p; |
| r = rb_entry(parent, struct ceph_snap_realm, node); |
| if (new->ino < r->ino) |
| p = &(*p)->rb_left; |
| else if (new->ino > r->ino) |
| p = &(*p)->rb_right; |
| else |
| BUG(); |
| } |
| |
| rb_link_node(&new->node, parent, p); |
| rb_insert_color(&new->node, root); |
| } |
| |
| /* |
| * create and get the realm rooted at @ino and bump its ref count. |
| * |
| * caller must hold snap_rwsem for write. |
| */ |
| static struct ceph_snap_realm *ceph_create_snap_realm( |
| struct ceph_mds_client *mdsc, |
| u64 ino) |
| { |
| struct ceph_snap_realm *realm; |
| |
| realm = kzalloc(sizeof(*realm), GFP_NOFS); |
| if (!realm) |
| return ERR_PTR(-ENOMEM); |
| |
| atomic_set(&realm->nref, 1); /* for caller */ |
| realm->ino = ino; |
| INIT_LIST_HEAD(&realm->children); |
| INIT_LIST_HEAD(&realm->child_item); |
| INIT_LIST_HEAD(&realm->empty_item); |
| INIT_LIST_HEAD(&realm->dirty_item); |
| INIT_LIST_HEAD(&realm->inodes_with_caps); |
| spin_lock_init(&realm->inodes_with_caps_lock); |
| __insert_snap_realm(&mdsc->snap_realms, realm); |
| dout("create_snap_realm %llx %p\n", realm->ino, realm); |
| return realm; |
| } |
| |
| /* |
| * lookup the realm rooted at @ino. |
| * |
| * caller must hold snap_rwsem for write. |
| */ |
| static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc, |
| u64 ino) |
| { |
| struct rb_node *n = mdsc->snap_realms.rb_node; |
| struct ceph_snap_realm *r; |
| |
| while (n) { |
| r = rb_entry(n, struct ceph_snap_realm, node); |
| if (ino < r->ino) |
| n = n->rb_left; |
| else if (ino > r->ino) |
| n = n->rb_right; |
| else { |
| dout("lookup_snap_realm %llx %p\n", r->ino, r); |
| return r; |
| } |
| } |
| return NULL; |
| } |
| |
| struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc, |
| u64 ino) |
| { |
| struct ceph_snap_realm *r; |
| r = __lookup_snap_realm(mdsc, ino); |
| if (r) |
| ceph_get_snap_realm(mdsc, r); |
| return r; |
| } |
| |
| static void __put_snap_realm(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm); |
| |
| /* |
| * called with snap_rwsem (write) |
| */ |
| static void __destroy_snap_realm(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm) |
| { |
| dout("__destroy_snap_realm %p %llx\n", realm, realm->ino); |
| |
| rb_erase(&realm->node, &mdsc->snap_realms); |
| |
| if (realm->parent) { |
| list_del_init(&realm->child_item); |
| __put_snap_realm(mdsc, realm->parent); |
| } |
| |
| kfree(realm->prior_parent_snaps); |
| kfree(realm->snaps); |
| ceph_put_snap_context(realm->cached_context); |
| kfree(realm); |
| } |
| |
| /* |
| * caller holds snap_rwsem (write) |
| */ |
| static void __put_snap_realm(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm) |
| { |
| dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, |
| atomic_read(&realm->nref), atomic_read(&realm->nref)-1); |
| if (atomic_dec_and_test(&realm->nref)) |
| __destroy_snap_realm(mdsc, realm); |
| } |
| |
| /* |
| * caller needn't hold any locks |
| */ |
| void ceph_put_snap_realm(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm) |
| { |
| dout("put_snap_realm %llx %p %d -> %d\n", realm->ino, realm, |
| atomic_read(&realm->nref), atomic_read(&realm->nref)-1); |
| if (!atomic_dec_and_test(&realm->nref)) |
| return; |
| |
| if (down_write_trylock(&mdsc->snap_rwsem)) { |
| __destroy_snap_realm(mdsc, realm); |
| up_write(&mdsc->snap_rwsem); |
| } else { |
| spin_lock(&mdsc->snap_empty_lock); |
| list_add(&realm->empty_item, &mdsc->snap_empty); |
| spin_unlock(&mdsc->snap_empty_lock); |
| } |
| } |
| |
| /* |
| * Clean up any realms whose ref counts have dropped to zero. Note |
| * that this does not include realms who were created but not yet |
| * used. |
| * |
| * Called under snap_rwsem (write) |
| */ |
| static void __cleanup_empty_realms(struct ceph_mds_client *mdsc) |
| { |
| struct ceph_snap_realm *realm; |
| |
| spin_lock(&mdsc->snap_empty_lock); |
| while (!list_empty(&mdsc->snap_empty)) { |
| realm = list_first_entry(&mdsc->snap_empty, |
| struct ceph_snap_realm, empty_item); |
| list_del(&realm->empty_item); |
| spin_unlock(&mdsc->snap_empty_lock); |
| __destroy_snap_realm(mdsc, realm); |
| spin_lock(&mdsc->snap_empty_lock); |
| } |
| spin_unlock(&mdsc->snap_empty_lock); |
| } |
| |
| void ceph_cleanup_empty_realms(struct ceph_mds_client *mdsc) |
| { |
| down_write(&mdsc->snap_rwsem); |
| __cleanup_empty_realms(mdsc); |
| up_write(&mdsc->snap_rwsem); |
| } |
| |
| /* |
| * adjust the parent realm of a given @realm. adjust child list, and parent |
| * pointers, and ref counts appropriately. |
| * |
| * return true if parent was changed, 0 if unchanged, <0 on error. |
| * |
| * caller must hold snap_rwsem for write. |
| */ |
| static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc, |
| struct ceph_snap_realm *realm, |
| u64 parentino) |
| { |
| struct ceph_snap_realm *parent; |
| |
| if (realm->parent_ino == parentino) |
| return 0; |
| |
| parent = ceph_lookup_snap_realm(mdsc, parentino); |
| if (!parent) { |
| parent = ceph_create_snap_realm(mdsc, parentino); |
| if (IS_ERR(parent)) |
| return PTR_ERR(parent); |
| } |
| dout("adjust_snap_realm_parent %llx %p: %llx %p -> %llx %p\n", |
| realm->ino, realm, realm->parent_ino, realm->parent, |
| parentino, parent); |
| if (realm->parent) { |
| list_del_init(&realm->child_item); |
| ceph_put_snap_realm(mdsc, realm->parent); |
| } |
| realm->parent_ino = parentino; |
| realm->parent = parent; |
| list_add(&realm->child_item, &parent->children); |
| return 1; |
| } |
| |
| |
| static int cmpu64_rev(const void *a, const void *b) |
| { |
| if (*(u64 *)a < *(u64 *)b) |
| return 1; |
| if (*(u64 *)a > *(u64 *)b) |
| return -1; |
| return 0; |
| } |
| |
| |
| struct ceph_snap_context *ceph_empty_snapc; |
| |
| /* |
| * build the snap context for a given realm. |
| */ |
| static int build_snap_context(struct ceph_snap_realm *realm) |
| { |
| struct ceph_snap_realm *parent = realm->parent; |
| struct ceph_snap_context *snapc; |
| int err = 0; |
| u32 num = realm->num_prior_parent_snaps + realm->num_snaps; |
| |
| /* |
| * build parent context, if it hasn't been built. |
| * conservatively estimate that all parent snaps might be |
| * included by us. |
| */ |
| if (parent) { |
| if (!parent->cached_context) { |
| err = build_snap_context(parent); |
| if (err) |
| goto fail; |
| } |
| num += parent->cached_context->num_snaps; |
| } |
| |
| /* do i actually need to update? not if my context seq |
| matches realm seq, and my parents' does to. (this works |
| because we rebuild_snap_realms() works _downward_ in |
| hierarchy after each update.) */ |
| if (realm->cached_context && |
| realm->cached_context->seq == realm->seq && |
| (!parent || |
| realm->cached_context->seq >= parent->cached_context->seq)) { |
| dout("build_snap_context %llx %p: %p seq %lld (%u snaps)" |
| " (unchanged)\n", |
| realm->ino, realm, realm->cached_context, |
| realm->cached_context->seq, |
| (unsigned int) realm->cached_context->num_snaps); |
| return 0; |
| } |
| |
| /* alloc new snap context */ |
| err = -ENOMEM; |
| if (num > (SIZE_MAX - sizeof(*snapc)) / sizeof(u64)) |
| goto fail; |
| snapc = ceph_create_snap_context(num, GFP_NOFS); |
| if (!snapc) |
| goto fail; |
| |
| /* build (reverse sorted) snap vector */ |
| num = 0; |
| snapc->seq = realm->seq; |
| if (parent) { |
| u32 i; |
| |
| /* include any of parent's snaps occurring _after_ my |
| parent became my parent */ |
| for (i = 0; i < parent->cached_context->num_snaps; i++) |
| if (parent->cached_context->snaps[i] >= |
| realm->parent_since) |
| snapc->snaps[num++] = |
| parent->cached_context->snaps[i]; |
| if (parent->cached_context->seq > snapc->seq) |
| snapc->seq = parent->cached_context->seq; |
| } |
| memcpy(snapc->snaps + num, realm->snaps, |
| sizeof(u64)*realm->num_snaps); |
| num += realm->num_snaps; |
| memcpy(snapc->snaps + num, realm->prior_parent_snaps, |
| sizeof(u64)*realm->num_prior_parent_snaps); |
| num += realm->num_prior_parent_snaps; |
| |
| sort(snapc->snaps, num, sizeof(u64), cmpu64_rev, NULL); |
| snapc->num_snaps = num; |
| dout("build_snap_context %llx %p: %p seq %lld (%u snaps)\n", |
| realm->ino, realm, snapc, snapc->seq, |
| (unsigned int) snapc->num_snaps); |
| |
| ceph_put_snap_context(realm->cached_context); |
| realm->cached_context = snapc; |
| return 0; |
| |
| fail: |
| /* |
| * if we fail, clear old (incorrect) cached_context... hopefully |
| * we'll have better luck building it later |
| */ |
| if (realm->cached_context) { |
| ceph_put_snap_context(realm->cached_context); |
| realm->cached_context = NULL; |
| } |
| pr_err("build_snap_context %llx %p fail %d\n", realm->ino, |
| realm, err); |
| return err; |
| } |
| |
| /* |
| * rebuild snap context for the given realm and all of its children. |
| */ |
| static void rebuild_snap_realms(struct ceph_snap_realm *realm) |
| { |
| struct ceph_snap_realm *child; |
| |
| dout("rebuild_snap_realms %llx %p\n", realm->ino, realm); |
| build_snap_context(realm); |
| |
| list_for_each_entry(child, &realm->children, child_item) |
| rebuild_snap_realms(child); |
| } |
| |
| |
| /* |
| * helper to allocate and decode an array of snapids. free prior |
| * instance, if any. |
| */ |
| static int dup_array(u64 **dst, __le64 *src, u32 num) |
| { |
| u32 i; |
| |
| kfree(*dst); |
| if (num) { |
| *dst = kcalloc(num, sizeof(u64), GFP_NOFS); |
| if (!*dst) |
| return -ENOMEM; |
| for (i = 0; i < num; i++) |
| (*dst)[i] = get_unaligned_le64(src + i); |
| } else { |
| *dst = NULL; |
| } |
| return 0; |
| } |
| |
| static bool has_new_snaps(struct ceph_snap_context *o, |
| struct ceph_snap_context *n) |
| { |
| if (n->num_snaps == 0) |
| return false; |
| /* snaps are in descending order */ |
| return n->snaps[0] > o->seq; |
| } |
| |
| /* |
| * When a snapshot is applied, the size/mtime inode metadata is queued |
| * in a ceph_cap_snap (one for each snapshot) until writeback |
| * completes and the metadata can be flushed back to the MDS. |
| * |
| * However, if a (sync) write is currently in-progress when we apply |
| * the snapshot, we have to wait until the write succeeds or fails |
| * (and a final size/mtime is known). In this case the |
| * cap_snap->writing = 1, and is said to be "pending." When the write |
| * finishes, we __ceph_finish_cap_snap(). |
| * |
| * Caller must hold snap_rwsem for read (i.e., the realm topology won't |
| * change). |
| */ |
| void ceph_queue_cap_snap(struct ceph_inode_info *ci) |
| { |
| struct inode *inode = &ci->vfs_inode; |
| struct ceph_cap_snap *capsnap; |
| struct ceph_snap_context *old_snapc, *new_snapc; |
| int used, dirty; |
| |
| capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS); |
| if (!capsnap) { |
| pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode); |
| return; |
| } |
| |
| spin_lock(&ci->i_ceph_lock); |
| used = __ceph_caps_used(ci); |
| dirty = __ceph_caps_dirty(ci); |
| |
| old_snapc = ci->i_head_snapc; |
| new_snapc = ci->i_snap_realm->cached_context; |
| |
| /* |
| * If there is a write in progress, treat that as a dirty Fw, |
| * even though it hasn't completed yet; by the time we finish |
| * up this capsnap it will be. |
| */ |
| if (used & CEPH_CAP_FILE_WR) |
| dirty |= CEPH_CAP_FILE_WR; |
| |
| if (__ceph_have_pending_cap_snap(ci)) { |
| /* there is no point in queuing multiple "pending" cap_snaps, |
| as no new writes are allowed to start when pending, so any |
| writes in progress now were started before the previous |
| cap_snap. lucky us. */ |
| dout("queue_cap_snap %p already pending\n", inode); |
| goto update_snapc; |
| } |
| if (ci->i_wrbuffer_ref_head == 0 && |
| !(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) { |
| dout("queue_cap_snap %p nothing dirty|writing\n", inode); |
| goto update_snapc; |
| } |
| |
| BUG_ON(!old_snapc); |
| |
| /* |
| * There is no need to send FLUSHSNAP message to MDS if there is |
| * no new snapshot. But when there is dirty pages or on-going |
| * writes, we still need to create cap_snap. cap_snap is needed |
| * by the write path and page writeback path. |
| * |
| * also see ceph_try_drop_cap_snap() |
| */ |
| if (has_new_snaps(old_snapc, new_snapc)) { |
| if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR)) |
| capsnap->need_flush = true; |
| } else { |
| if (!(used & CEPH_CAP_FILE_WR) && |
| ci->i_wrbuffer_ref_head == 0) { |
| dout("queue_cap_snap %p " |
| "no new_snap|dirty_page|writing\n", inode); |
| goto update_snapc; |
| } |
| } |
| |
| dout("queue_cap_snap %p cap_snap %p queuing under %p %s %s\n", |
| inode, capsnap, old_snapc, ceph_cap_string(dirty), |
| capsnap->need_flush ? "" : "no_flush"); |
| ihold(inode); |
| |
| atomic_set(&capsnap->nref, 1); |
| capsnap->ci = ci; |
| INIT_LIST_HEAD(&capsnap->ci_item); |
| INIT_LIST_HEAD(&capsnap->flushing_item); |
| |
| capsnap->follows = old_snapc->seq; |
| capsnap->issued = __ceph_caps_issued(ci, NULL); |
| capsnap->dirty = dirty; |
| |
| capsnap->mode = inode->i_mode; |
| capsnap->uid = inode->i_uid; |
| capsnap->gid = inode->i_gid; |
| |
| if (dirty & CEPH_CAP_XATTR_EXCL) { |
| __ceph_build_xattrs_blob(ci); |
| capsnap->xattr_blob = |
| ceph_buffer_get(ci->i_xattrs.blob); |
| capsnap->xattr_version = ci->i_xattrs.version; |
| } else { |
| capsnap->xattr_blob = NULL; |
| capsnap->xattr_version = 0; |
| } |
| |
| capsnap->inline_data = ci->i_inline_version != CEPH_INLINE_NONE; |
| |
| /* dirty page count moved from _head to this cap_snap; |
| all subsequent writes page dirties occur _after_ this |
| snapshot. */ |
| capsnap->dirty_pages = ci->i_wrbuffer_ref_head; |
| ci->i_wrbuffer_ref_head = 0; |
| capsnap->context = old_snapc; |
| list_add_tail(&capsnap->ci_item, &ci->i_cap_snaps); |
| old_snapc = NULL; |
| |
| if (used & CEPH_CAP_FILE_WR) { |
| dout("queue_cap_snap %p cap_snap %p snapc %p" |
| " seq %llu used WR, now pending\n", inode, |
| capsnap, old_snapc, old_snapc->seq); |
| capsnap->writing = 1; |
| } else { |
| /* note mtime, size NOW. */ |
| __ceph_finish_cap_snap(ci, capsnap); |
| } |
| capsnap = NULL; |
| |
| update_snapc: |
| if (ci->i_head_snapc) { |
| ci->i_head_snapc = ceph_get_snap_context(new_snapc); |
| dout(" new snapc is %p\n", new_snapc); |
| } |
| spin_unlock(&ci->i_ceph_lock); |
| |
| kfree(capsnap); |
| ceph_put_snap_context(old_snapc); |
| } |
| |
| /* |
| * Finalize the size, mtime for a cap_snap.. that is, settle on final values |
| * to be used for the snapshot, to be flushed back to the mds. |
| * |
| * If capsnap can now be flushed, add to snap_flush list, and return 1. |
| * |
| * Caller must hold i_ceph_lock. |
| */ |
| int __ceph_finish_cap_snap(struct ceph_inode_info *ci, |
| struct ceph_cap_snap *capsnap) |
| { |
| struct inode *inode = &ci->vfs_inode; |
| struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc; |
| |
| BUG_ON(capsnap->writing); |
| capsnap->size = inode->i_size; |
| capsnap->mtime = inode->i_mtime; |
| capsnap->atime = inode->i_atime; |
| capsnap->ctime = inode->i_ctime; |
| capsnap->time_warp_seq = ci->i_time_warp_seq; |
| if (capsnap->dirty_pages) { |
| dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu " |
| "still has %d dirty pages\n", inode, capsnap, |
| capsnap->context, capsnap->context->seq, |
| ceph_cap_string(capsnap->dirty), capsnap->size, |
| capsnap->dirty_pages); |
| return 0; |
| } |
| dout("finish_cap_snap %p cap_snap %p snapc %p %llu %s s=%llu\n", |
| inode, capsnap, capsnap->context, |
| capsnap->context->seq, ceph_cap_string(capsnap->dirty), |
| capsnap->size); |
| |
| spin_lock(&mdsc->snap_flush_lock); |
| if (list_empty(&ci->i_snap_flush_item)) |
| list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list); |
| spin_unlock(&mdsc->snap_flush_lock); |
| return 1; /* caller may want to ceph_flush_snaps */ |
| } |
| |
| /* |
| * Queue cap_snaps for snap writeback for this realm and its children. |
| * Called under snap_rwsem, so realm topology won't change. |
| */ |
| static void queue_realm_cap_snaps(struct ceph_snap_realm *realm) |
| { |
| struct ceph_inode_info *ci; |
| struct inode *lastinode = NULL; |
| struct ceph_snap_realm *child; |
| |
| dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino); |
| |
| spin_lock(&realm->inodes_with_caps_lock); |
| list_for_each_entry(ci, &realm->inodes_with_caps, |
| i_snap_realm_item) { |
| struct inode *inode = igrab(&ci->vfs_inode); |
| if (!inode) |
| continue; |
| spin_unlock(&realm->inodes_with_caps_lock); |
| iput(lastinode); |
| lastinode = inode; |
| ceph_queue_cap_snap(ci); |
| spin_lock(&realm->inodes_with_caps_lock); |
| } |
| spin_unlock(&realm->inodes_with_caps_lock); |
| iput(lastinode); |
| |
| list_for_each_entry(child, &realm->children, child_item) { |
| dout("queue_realm_cap_snaps %p %llx queue child %p %llx\n", |
| realm, realm->ino, child, child->ino); |
| list_del_init(&child->dirty_item); |
| list_add(&child->dirty_item, &realm->dirty_item); |
| } |
| |
| list_del_init(&realm->dirty_item); |
| dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino); |
| } |
| |
| /* |
| * Parse and apply a snapblob "snap trace" from the MDS. This specifies |
| * the snap realm parameters from a given realm and all of its ancestors, |
| * up to the root. |
| * |
| * Caller must hold snap_rwsem for write. |
| */ |
| int ceph_update_snap_trace(struct ceph_mds_client *mdsc, |
| void *p, void *e, bool deletion, |
| struct ceph_snap_realm **realm_ret) |
| { |
| struct ceph_mds_snap_realm *ri; /* encoded */ |
| __le64 *snaps; /* encoded */ |
| __le64 *prior_parent_snaps; /* encoded */ |
| struct ceph_snap_realm *realm = NULL; |
| struct ceph_snap_realm *first_realm = NULL; |
| int invalidate = 0; |
| int err = -ENOMEM; |
| LIST_HEAD(dirty_realms); |
| |
| dout("update_snap_trace deletion=%d\n", deletion); |
| more: |
| ceph_decode_need(&p, e, sizeof(*ri), bad); |
| ri = p; |
| p += sizeof(*ri); |
| ceph_decode_need(&p, e, sizeof(u64)*(le32_to_cpu(ri->num_snaps) + |
| le32_to_cpu(ri->num_prior_parent_snaps)), bad); |
| snaps = p; |
| p += sizeof(u64) * le32_to_cpu(ri->num_snaps); |
| prior_parent_snaps = p; |
| p += sizeof(u64) * le32_to_cpu(ri->num_prior_parent_snaps); |
| |
| realm = ceph_lookup_snap_realm(mdsc, le64_to_cpu(ri->ino)); |
| if (!realm) { |
| realm = ceph_create_snap_realm(mdsc, le64_to_cpu(ri->ino)); |
| if (IS_ERR(realm)) { |
| err = PTR_ERR(realm); |
| goto fail; |
| } |
| } |
| |
| /* ensure the parent is correct */ |
| err = adjust_snap_realm_parent(mdsc, realm, le64_to_cpu(ri->parent)); |
| if (err < 0) |
| goto fail; |
| invalidate += err; |
| |
| if (le64_to_cpu(ri->seq) > realm->seq) { |
| dout("update_snap_trace updating %llx %p %lld -> %lld\n", |
| realm->ino, realm, realm->seq, le64_to_cpu(ri->seq)); |
| /* update realm parameters, snap lists */ |
| realm->seq = le64_to_cpu(ri->seq); |
| realm->created = le64_to_cpu(ri->created); |
| realm->parent_since = le64_to_cpu(ri->parent_since); |
| |
| realm->num_snaps = le32_to_cpu(ri->num_snaps); |
| err = dup_array(&realm->snaps, snaps, realm->num_snaps); |
| if (err < 0) |
| goto fail; |
| |
| realm->num_prior_parent_snaps = |
| le32_to_cpu(ri->num_prior_parent_snaps); |
| err = dup_array(&realm->prior_parent_snaps, prior_parent_snaps, |
| realm->num_prior_parent_snaps); |
| if (err < 0) |
| goto fail; |
| |
| /* queue realm for cap_snap creation */ |
| list_add(&realm->dirty_item, &dirty_realms); |
| if (realm->seq > mdsc->last_snap_seq) |
| mdsc->last_snap_seq = realm->seq; |
| |
| invalidate = 1; |
| } else if (!realm->cached_context) { |
| dout("update_snap_trace %llx %p seq %lld new\n", |
| realm->ino, realm, realm->seq); |
| invalidate = 1; |
| } else { |
| dout("update_snap_trace %llx %p seq %lld unchanged\n", |
| realm->ino, realm, realm->seq); |
| } |
| |
| dout("done with %llx %p, invalidated=%d, %p %p\n", realm->ino, |
| realm, invalidate, p, e); |
| |
| /* invalidate when we reach the _end_ (root) of the trace */ |
| if (invalidate && p >= e) |
| rebuild_snap_realms(realm); |
| |
| if (!first_realm) |
| first_realm = realm; |
| else |
| ceph_put_snap_realm(mdsc, realm); |
| |
| if (p < e) |
| goto more; |
| |
| /* |
| * queue cap snaps _after_ we've built the new snap contexts, |
| * so that i_head_snapc can be set appropriately. |
| */ |
| while (!list_empty(&dirty_realms)) { |
| realm = list_first_entry(&dirty_realms, struct ceph_snap_realm, |
| dirty_item); |
| queue_realm_cap_snaps(realm); |
| } |
| |
| if (realm_ret) |
| *realm_ret = first_realm; |
| else |
| ceph_put_snap_realm(mdsc, first_realm); |
| |
| __cleanup_empty_realms(mdsc); |
| return 0; |
| |
| bad: |
| err = -EINVAL; |
| fail: |
| if (realm && !IS_ERR(realm)) |
| ceph_put_snap_realm(mdsc, realm); |
| if (first_realm) |
| ceph_put_snap_realm(mdsc, first_realm); |
| pr_err("update_snap_trace error %d\n", err); |
| return err; |
| } |
| |
| |
| /* |
| * Send any cap_snaps that are queued for flush. Try to carry |
| * s_mutex across multiple snap flushes to avoid locking overhead. |
| * |
| * Caller holds no locks. |
| */ |
| static void flush_snaps(struct ceph_mds_client *mdsc) |
| { |
| struct ceph_inode_info *ci; |
| struct inode *inode; |
| struct ceph_mds_session *session = NULL; |
| |
| dout("flush_snaps\n"); |
| spin_lock(&mdsc->snap_flush_lock); |
| while (!list_empty(&mdsc->snap_flush_list)) { |
| ci = list_first_entry(&mdsc->snap_flush_list, |
| struct ceph_inode_info, i_snap_flush_item); |
| inode = &ci->vfs_inode; |
| ihold(inode); |
| spin_unlock(&mdsc->snap_flush_lock); |
| spin_lock(&ci->i_ceph_lock); |
| __ceph_flush_snaps(ci, &session, 0); |
| spin_unlock(&ci->i_ceph_lock); |
| iput(inode); |
| spin_lock(&mdsc->snap_flush_lock); |
| } |
| spin_unlock(&mdsc->snap_flush_lock); |
| |
| if (session) { |
| mutex_unlock(&session->s_mutex); |
| ceph_put_mds_session(session); |
| } |
| dout("flush_snaps done\n"); |
| } |
| |
| |
| /* |
| * Handle a snap notification from the MDS. |
| * |
| * This can take two basic forms: the simplest is just a snap creation |
| * or deletion notification on an existing realm. This should update the |
| * realm and its children. |
| * |
| * The more difficult case is realm creation, due to snap creation at a |
| * new point in the file hierarchy, or due to a rename that moves a file or |
| * directory into another realm. |
| */ |
| void ceph_handle_snap(struct ceph_mds_client *mdsc, |
| struct ceph_mds_session *session, |
| struct ceph_msg *msg) |
| { |
| struct super_block *sb = mdsc->fsc->sb; |
| int mds = session->s_mds; |
| u64 split; |
| int op; |
| int trace_len; |
| struct ceph_snap_realm *realm = NULL; |
| void *p = msg->front.iov_base; |
| void *e = p + msg->front.iov_len; |
| struct ceph_mds_snap_head *h; |
| int num_split_inos, num_split_realms; |
| __le64 *split_inos = NULL, *split_realms = NULL; |
| int i; |
| int locked_rwsem = 0; |
| |
| /* decode */ |
| if (msg->front.iov_len < sizeof(*h)) |
| goto bad; |
| h = p; |
| op = le32_to_cpu(h->op); |
| split = le64_to_cpu(h->split); /* non-zero if we are splitting an |
| * existing realm */ |
| num_split_inos = le32_to_cpu(h->num_split_inos); |
| num_split_realms = le32_to_cpu(h->num_split_realms); |
| trace_len = le32_to_cpu(h->trace_len); |
| p += sizeof(*h); |
| |
| dout("handle_snap from mds%d op %s split %llx tracelen %d\n", mds, |
| ceph_snap_op_name(op), split, trace_len); |
| |
| mutex_lock(&session->s_mutex); |
| session->s_seq++; |
| mutex_unlock(&session->s_mutex); |
| |
| down_write(&mdsc->snap_rwsem); |
| locked_rwsem = 1; |
| |
| if (op == CEPH_SNAP_OP_SPLIT) { |
| struct ceph_mds_snap_realm *ri; |
| |
| /* |
| * A "split" breaks part of an existing realm off into |
| * a new realm. The MDS provides a list of inodes |
| * (with caps) and child realms that belong to the new |
| * child. |
| */ |
| split_inos = p; |
| p += sizeof(u64) * num_split_inos; |
| split_realms = p; |
| p += sizeof(u64) * num_split_realms; |
| ceph_decode_need(&p, e, sizeof(*ri), bad); |
| /* we will peek at realm info here, but will _not_ |
| * advance p, as the realm update will occur below in |
| * ceph_update_snap_trace. */ |
| ri = p; |
| |
| realm = ceph_lookup_snap_realm(mdsc, split); |
| if (!realm) { |
| realm = ceph_create_snap_realm(mdsc, split); |
| if (IS_ERR(realm)) |
| goto out; |
| } |
| |
| dout("splitting snap_realm %llx %p\n", realm->ino, realm); |
| for (i = 0; i < num_split_inos; i++) { |
| struct ceph_vino vino = { |
| .ino = le64_to_cpu(split_inos[i]), |
| .snap = CEPH_NOSNAP, |
| }; |
| struct inode *inode = ceph_find_inode(sb, vino); |
| struct ceph_inode_info *ci; |
| struct ceph_snap_realm *oldrealm; |
| |
| if (!inode) |
| continue; |
| ci = ceph_inode(inode); |
| |
| spin_lock(&ci->i_ceph_lock); |
| if (!ci->i_snap_realm) |
| goto skip_inode; |
| /* |
| * If this inode belongs to a realm that was |
| * created after our new realm, we experienced |
| * a race (due to another split notifications |
| * arriving from a different MDS). So skip |
| * this inode. |
| */ |
| if (ci->i_snap_realm->created > |
| le64_to_cpu(ri->created)) { |
| dout(" leaving %p in newer realm %llx %p\n", |
| inode, ci->i_snap_realm->ino, |
| ci->i_snap_realm); |
| goto skip_inode; |
| } |
| dout(" will move %p to split realm %llx %p\n", |
| inode, realm->ino, realm); |
| /* |
| * Move the inode to the new realm |
| */ |
| spin_lock(&realm->inodes_with_caps_lock); |
| list_del_init(&ci->i_snap_realm_item); |
| list_add(&ci->i_snap_realm_item, |
| &realm->inodes_with_caps); |
| oldrealm = ci->i_snap_realm; |
| ci->i_snap_realm = realm; |
| spin_unlock(&realm->inodes_with_caps_lock); |
| spin_unlock(&ci->i_ceph_lock); |
| |
| ceph_get_snap_realm(mdsc, realm); |
| ceph_put_snap_realm(mdsc, oldrealm); |
| |
| iput(inode); |
| continue; |
| |
| skip_inode: |
| spin_unlock(&ci->i_ceph_lock); |
| iput(inode); |
| } |
| |
| /* we may have taken some of the old realm's children. */ |
| for (i = 0; i < num_split_realms; i++) { |
| struct ceph_snap_realm *child = |
| __lookup_snap_realm(mdsc, |
| le64_to_cpu(split_realms[i])); |
| if (!child) |
| continue; |
| adjust_snap_realm_parent(mdsc, child, realm->ino); |
| } |
| } |
| |
| /* |
| * update using the provided snap trace. if we are deleting a |
| * snap, we can avoid queueing cap_snaps. |
| */ |
| ceph_update_snap_trace(mdsc, p, e, |
| op == CEPH_SNAP_OP_DESTROY, NULL); |
| |
| if (op == CEPH_SNAP_OP_SPLIT) |
| /* we took a reference when we created the realm, above */ |
| ceph_put_snap_realm(mdsc, realm); |
| |
| __cleanup_empty_realms(mdsc); |
| |
| up_write(&mdsc->snap_rwsem); |
| |
| flush_snaps(mdsc); |
| return; |
| |
| bad: |
| pr_err("corrupt snap message from mds%d\n", mds); |
| ceph_msg_dump(msg); |
| out: |
| if (locked_rwsem) |
| up_write(&mdsc->snap_rwsem); |
| return; |
| } |
| |
| int __init ceph_snap_init(void) |
| { |
| ceph_empty_snapc = ceph_create_snap_context(0, GFP_NOFS); |
| if (!ceph_empty_snapc) |
| return -ENOMEM; |
| ceph_empty_snapc->seq = 1; |
| return 0; |
| } |
| |
| void ceph_snap_exit(void) |
| { |
| ceph_put_snap_context(ceph_empty_snapc); |
| } |