From 28da9fb4467f7a650cd31af6dfad3a4e4a3abf6e Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Thu, 21 Jun 2012 10:59:13 +0200 Subject: Btrfs: fix tree mod log for root replacements at leaf level For the tree mod log, we don't log any operations at leaf level. If the root is at the leaf level (i.e. the tree consists only of the root), then __tree_mod_log_oldest_root will find a ROOT_REPLACE operation in the log (because we always log that one no matter which level), but no other operations. With this patch __tree_mod_log_oldest_root exits cleanly instead of BUGging in this situation. get_old_root checks if its really a root at leaf level in case we don't have any operations and WARNs if this assumption breaks. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 15cbc2bf4ff0..7d1e4fc5fb6a 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1024,11 +1024,18 @@ __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info, if (!looped && !tm) return 0; /* - * we must have key remove operations in the log before the - * replace operation. + * if there are no tree operation for the oldest root, we simply + * return it. this should only happen if that (old) root is at + * level 0. */ - BUG_ON(!tm); + if (!tm) + break; + /* + * if there's an operation that's not a root replacement, we + * found the oldest version of our root. normally, we'll find a + * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here. + */ if (tm->op != MOD_LOG_ROOT_REPLACE) break; @@ -1192,16 +1199,8 @@ get_old_root(struct btrfs_root *root, u64 time_seq) } tm = tree_mod_log_search(root->fs_info, logical, time_seq); - /* - * there was an item in the log when __tree_mod_log_oldest_root - * returned. this one must not go away, because the time_seq passed to - * us must be blocking its removal. - */ - BUG_ON(!tm); - if (old_root) - eb = alloc_dummy_extent_buffer(tm->index << PAGE_CACHE_SHIFT, - root->nodesize); + eb = alloc_dummy_extent_buffer(logical, root->nodesize); else eb = btrfs_clone_extent_buffer(root->node); btrfs_tree_read_unlock(root->node); @@ -1216,7 +1215,10 @@ get_old_root(struct btrfs_root *root, u64 time_seq) btrfs_set_header_level(eb, old_root->level); btrfs_set_header_generation(eb, old_generation); } - __tree_mod_log_rewind(eb, time_seq, tm); + if (tm) + __tree_mod_log_rewind(eb, time_seq, tm); + else + WARN_ON(btrfs_header_level(eb) != 0); extent_buffer_get(eb); return eb; -- cgit v1.2.3 From c3e0696523862c48b4d8c73ffb2867e9db478338 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Thu, 21 Jun 2012 11:01:06 +0200 Subject: Btrfs: always put insert_ptr modifications into the tree mod log Several callers of insert_ptr set the tree_mod_log parameter to 0 to avoid addition to the tree mod log. In fact, we need all of those operations. This commit simply removes the additional parameter and makes addition to the tree mod log unconditional. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 7d1e4fc5fb6a..e005d9b04616 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2997,7 +2997,7 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans, static void insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_disk_key *key, u64 bytenr, - int slot, int level, int tree_mod_log) + int slot, int level) { struct extent_buffer *lower; int nritems; @@ -3010,7 +3010,7 @@ static void insert_ptr(struct btrfs_trans_handle *trans, BUG_ON(slot > nritems); BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root)); if (slot != nritems) { - if (tree_mod_log && level) + if (level) tree_mod_log_eb_move(root->fs_info, lower, slot + 1, slot, nritems - slot); memmove_extent_buffer(lower, @@ -3018,7 +3018,7 @@ static void insert_ptr(struct btrfs_trans_handle *trans, btrfs_node_key_ptr_offset(slot), (nritems - slot) * sizeof(struct btrfs_key_ptr)); } - if (tree_mod_log && level) { + if (level) { ret = tree_mod_log_insert_key(root->fs_info, lower, slot, MOD_LOG_KEY_ADD); BUG_ON(ret < 0); @@ -3106,7 +3106,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans, btrfs_mark_buffer_dirty(split); insert_ptr(trans, root, path, &disk_key, split->start, - path->slots[level + 1] + 1, level + 1, 1); + path->slots[level + 1] + 1, level + 1); if (path->slots[level] >= mid) { path->slots[level] -= mid; @@ -3643,7 +3643,7 @@ static noinline void copy_for_split(struct btrfs_trans_handle *trans, btrfs_set_header_nritems(l, mid); btrfs_item_key(right, &disk_key, 0); insert_ptr(trans, root, path, &disk_key, right->start, - path->slots[1] + 1, 1, 0); + path->slots[1] + 1, 1); btrfs_mark_buffer_dirty(right); btrfs_mark_buffer_dirty(l); @@ -3850,7 +3850,7 @@ again: if (mid <= slot) { btrfs_set_header_nritems(right, 0); insert_ptr(trans, root, path, &disk_key, right->start, - path->slots[1] + 1, 1, 0); + path->slots[1] + 1, 1); btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; @@ -3859,7 +3859,7 @@ again: } else { btrfs_set_header_nritems(right, 0); insert_ptr(trans, root, path, &disk_key, right->start, - path->slots[1], 1, 0); + path->slots[1], 1); btrfs_tree_unlock(path->nodes[0]); free_extent_buffer(path->nodes[0]); path->nodes[0] = right; -- cgit v1.2.3 From 19956c7e94a7a58d6df8c4db5ae62f9109a7c663 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Fri, 22 Jun 2012 14:52:13 +0200 Subject: Btrfs: fix tree mod log rewind of ADD operations When a MOD_LOG_KEY_ADD operation is rewinded, we remove the key from the tree block. If its not the last key, removal involves a move operation. This move operation was explicitly done before this commit. However, at insertion time, there's a move operation before the actual addition to make room for the new key, which is recorded in the tree mod log as well. This means, we must drop the move operation when rewinding the add operation, because the next operation we'll be rewinding will be the corresponding MOD_LOG_MOVE_KEYS operation. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index e005d9b04616..b98f8604f4f6 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1094,11 +1094,7 @@ __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq, tm->generation); break; case MOD_LOG_KEY_ADD: - if (tm->slot != n - 1) { - o_dst = btrfs_node_key_ptr_offset(tm->slot); - o_src = btrfs_node_key_ptr_offset(tm->slot + 1); - memmove_extent_buffer(eb, o_dst, o_src, p_size); - } + /* if a move operation is needed it's in the log */ n--; break; case MOD_LOG_MOVE_KEYS: -- cgit v1.2.3 From d42244a0d36ad0939c5f173ebf15841a0678899c Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Fri, 22 Jun 2012 14:51:15 +0200 Subject: Btrfs: resolve tree mod log locking issue in btrfs_next_leaf With the tree mod log, we may end up with two roots (the current root and a rewinded version of it) both pointing to two leaves, l1 and l2, of which l2 had already been cow-ed in the current transaction. If we don't rewind any tree blocks, we cannot have two roots both pointing to an already cowed tree block. Now there is btrfs_next_leaf, which has a leaf locked and wants a lock on the next (right) leaf. And there is push_leaf_left, which has a (cowed!) leaf locked and wants a lock on the previous (left) leaf. In order to solve this dead lock situation, we use try_lock in btrfs_next_leaf (only in case it's called with a tree mod log time_seq paramter) and if we fail to get a lock on the next leaf, we give up our lock on the current leaf and retry from the very beginning. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index b98f8604f4f6..8206b3900587 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5119,6 +5119,18 @@ again: if (!path->skip_locking) { ret = btrfs_try_tree_read_lock(next); + if (!ret && time_seq) { + /* + * If we don't get the lock, we may be racing + * with push_leaf_left, holding that lock while + * itself waiting for the leaf we've currently + * locked. To solve this situation, we give up + * on our lock and cycle. + */ + btrfs_release_path(path); + cond_resched(); + goto again; + } if (!ret) { btrfs_set_path_blocking(path); btrfs_tree_read_lock(next); -- cgit v1.2.3 From cf5388307a2b4faab4b11d732b61c85741be6169 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Wed, 4 Jul 2012 15:42:48 +0200 Subject: Btrfs: fix buffer leak in btrfs_next_old_leaf When calling btrfs_next_old_leaf, we were leaking an extent buffer in the rare case of using the deadlock avoidance code needed for the tree mod log. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 8206b3900587..67fe46fdee6f 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5127,6 +5127,7 @@ again: * locked. To solve this situation, we give up * on our lock and cycle. */ + free_extent_buffer(next); btrfs_release_path(path); cond_resched(); goto again; -- cgit v1.2.3 From 097b8a7c9e48e2cb50fd0eb9315791921beaf484 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Thu, 21 Jun 2012 11:08:04 +0200 Subject: Btrfs: join tree mod log code with the code holding back delayed refs We've got two mechanisms both required for reliable backref resolving (tree mod log and holding back delayed refs). You cannot make use of one without the other. So instead of requiring the user of this mechanism to setup both correctly, we join them into a single interface. Additionally, we stop inserting non-blockers into fs_info->tree_mod_seq_list as we did before, which was of no value. Signed-off-by: Jan Schmidt --- fs/btrfs/ctree.c | 275 ++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 171 insertions(+), 104 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 67fe46fdee6f..bef68ab32204 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -321,7 +321,7 @@ struct tree_mod_root { struct tree_mod_elem { struct rb_node node; u64 index; /* shifted logical */ - struct seq_list elem; + u64 seq; enum mod_log_op op; /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */ @@ -341,20 +341,50 @@ struct tree_mod_elem { struct tree_mod_root old_root; }; -static inline void -__get_tree_mod_seq(struct btrfs_fs_info *fs_info, struct seq_list *elem) +static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info) { - elem->seq = atomic_inc_return(&fs_info->tree_mod_seq); - list_add_tail(&elem->list, &fs_info->tree_mod_seq_list); + read_lock(&fs_info->tree_mod_log_lock); } -void btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info, - struct seq_list *elem) +static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info) +{ + read_unlock(&fs_info->tree_mod_log_lock); +} + +static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info) +{ + write_lock(&fs_info->tree_mod_log_lock); +} + +static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info) { - elem->flags = 1; + write_unlock(&fs_info->tree_mod_log_lock); +} + +/* + * This adds a new blocker to the tree mod log's blocker list if the @elem + * passed does not already have a sequence number set. So when a caller expects + * to record tree modifications, it should ensure to set elem->seq to zero + * before calling btrfs_get_tree_mod_seq. + * Returns a fresh, unused tree log modification sequence number, even if no new + * blocker was added. + */ +u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info, + struct seq_list *elem) +{ + u64 seq; + + tree_mod_log_write_lock(fs_info); spin_lock(&fs_info->tree_mod_seq_lock); - __get_tree_mod_seq(fs_info, elem); + if (!elem->seq) { + elem->seq = btrfs_inc_tree_mod_seq(fs_info); + list_add_tail(&elem->list, &fs_info->tree_mod_seq_list); + } + seq = btrfs_inc_tree_mod_seq(fs_info); spin_unlock(&fs_info->tree_mod_seq_lock); + tree_mod_log_write_unlock(fs_info); + + return seq; } void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info, @@ -371,41 +401,46 @@ void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info, if (!seq_putting) return; - BUG_ON(!(elem->flags & 1)); spin_lock(&fs_info->tree_mod_seq_lock); list_del(&elem->list); + elem->seq = 0; list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) { - if ((cur_elem->flags & 1) && cur_elem->seq < min_seq) { + if (cur_elem->seq < min_seq) { if (seq_putting > cur_elem->seq) { /* * blocker with lower sequence number exists, we * cannot remove anything from the log */ - goto out; + spin_unlock(&fs_info->tree_mod_seq_lock); + return; } min_seq = cur_elem->seq; } } + spin_unlock(&fs_info->tree_mod_seq_lock); + + /* + * we removed the lowest blocker from the blocker list, so there may be + * more processible delayed refs. + */ + wake_up(&fs_info->tree_mod_seq_wait); /* * anything that's lower than the lowest existing (read: blocked) * sequence number can be removed from the tree. */ - write_lock(&fs_info->tree_mod_log_lock); + tree_mod_log_write_lock(fs_info); tm_root = &fs_info->tree_mod_log; for (node = rb_first(tm_root); node; node = next) { next = rb_next(node); tm = container_of(node, struct tree_mod_elem, node); - if (tm->elem.seq > min_seq) + if (tm->seq > min_seq) continue; rb_erase(node, tm_root); - list_del(&tm->elem.list); kfree(tm); } - write_unlock(&fs_info->tree_mod_log_lock); -out: - spin_unlock(&fs_info->tree_mod_seq_lock); + tree_mod_log_write_unlock(fs_info); } /* @@ -423,11 +458,9 @@ __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm) struct rb_node **new; struct rb_node *parent = NULL; struct tree_mod_elem *cur; - int ret = 0; - BUG_ON(!tm || !tm->elem.seq); + BUG_ON(!tm || !tm->seq); - write_lock(&fs_info->tree_mod_log_lock); tm_root = &fs_info->tree_mod_log; new = &tm_root->rb_node; while (*new) { @@ -437,88 +470,81 @@ __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm) new = &((*new)->rb_left); else if (cur->index > tm->index) new = &((*new)->rb_right); - else if (cur->elem.seq < tm->elem.seq) + else if (cur->seq < tm->seq) new = &((*new)->rb_left); - else if (cur->elem.seq > tm->elem.seq) + else if (cur->seq > tm->seq) new = &((*new)->rb_right); else { kfree(tm); - ret = -EEXIST; - goto unlock; + return -EEXIST; } } rb_link_node(&tm->node, parent, new); rb_insert_color(&tm->node, tm_root); -unlock: - write_unlock(&fs_info->tree_mod_log_lock); - return ret; + return 0; } +/* + * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it + * returns zero with the tree_mod_log_lock acquired. The caller must hold + * this until all tree mod log insertions are recorded in the rb tree and then + * call tree_mod_log_write_unlock() to release. + */ static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info, struct extent_buffer *eb) { smp_mb(); if (list_empty(&(fs_info)->tree_mod_seq_list)) return 1; - if (!eb) - return 0; - if (btrfs_header_level(eb) == 0) + if (eb && btrfs_header_level(eb) == 0) return 1; + + tree_mod_log_write_lock(fs_info); + if (list_empty(&fs_info->tree_mod_seq_list)) { + /* + * someone emptied the list while we were waiting for the lock. + * we must not add to the list when no blocker exists. + */ + tree_mod_log_write_unlock(fs_info); + return 1; + } + return 0; } /* - * This allocates memory and gets a tree modification sequence number when - * needed. + * This allocates memory and gets a tree modification sequence number. * - * Returns 0 when no sequence number is needed, < 0 on error. - * Returns 1 when a sequence number was added. In this case, - * fs_info->tree_mod_seq_lock was acquired and must be released by the caller - * after inserting into the rb tree. + * Returns <0 on error. + * Returns >0 (the added sequence number) on success. */ static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags, struct tree_mod_elem **tm_ret) { struct tree_mod_elem *tm; - int seq; - if (tree_mod_dont_log(fs_info, NULL)) - return 0; - - tm = *tm_ret = kzalloc(sizeof(*tm), flags); + /* + * once we switch from spin locks to something different, we should + * honor the flags parameter here. + */ + tm = *tm_ret = kzalloc(sizeof(*tm), GFP_ATOMIC); if (!tm) return -ENOMEM; - tm->elem.flags = 0; - spin_lock(&fs_info->tree_mod_seq_lock); - if (list_empty(&fs_info->tree_mod_seq_list)) { - /* - * someone emptied the list while we were waiting for the lock. - * we must not add to the list, because no blocker exists. items - * are removed from the list only when the existing blocker is - * removed from the list. - */ - kfree(tm); - seq = 0; - spin_unlock(&fs_info->tree_mod_seq_lock); - } else { - __get_tree_mod_seq(fs_info, &tm->elem); - seq = tm->elem.seq; - } - - return seq; + tm->seq = btrfs_inc_tree_mod_seq(fs_info); + return tm->seq; } -static noinline int -tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info, - struct extent_buffer *eb, int slot, - enum mod_log_op op, gfp_t flags) +static inline int +__tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, + struct extent_buffer *eb, int slot, + enum mod_log_op op, gfp_t flags) { - struct tree_mod_elem *tm; int ret; + struct tree_mod_elem *tm; ret = tree_mod_alloc(fs_info, flags, &tm); - if (ret <= 0) + if (ret < 0) return ret; tm->index = eb->start >> PAGE_CACHE_SHIFT; @@ -530,8 +556,22 @@ tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info, tm->slot = slot; tm->generation = btrfs_node_ptr_generation(eb, slot); - ret = __tree_mod_log_insert(fs_info, tm); - spin_unlock(&fs_info->tree_mod_seq_lock); + return __tree_mod_log_insert(fs_info, tm); +} + +static noinline int +tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info, + struct extent_buffer *eb, int slot, + enum mod_log_op op, gfp_t flags) +{ + int ret; + + if (tree_mod_dont_log(fs_info, eb)) + return 0; + + ret = __tree_mod_log_insert_key(fs_info, eb, slot, op, flags); + + tree_mod_log_write_unlock(fs_info); return ret; } @@ -542,6 +582,14 @@ tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, return tree_mod_log_insert_key_mask(fs_info, eb, slot, op, GFP_NOFS); } +static noinline int +tree_mod_log_insert_key_locked(struct btrfs_fs_info *fs_info, + struct extent_buffer *eb, int slot, + enum mod_log_op op) +{ + return __tree_mod_log_insert_key(fs_info, eb, slot, op, GFP_NOFS); +} + static noinline int tree_mod_log_insert_move(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, int dst_slot, int src_slot, @@ -555,14 +603,14 @@ tree_mod_log_insert_move(struct btrfs_fs_info *fs_info, return 0; for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) { - ret = tree_mod_log_insert_key(fs_info, eb, i + dst_slot, + ret = tree_mod_log_insert_key_locked(fs_info, eb, i + dst_slot, MOD_LOG_KEY_REMOVE_WHILE_MOVING); BUG_ON(ret < 0); } ret = tree_mod_alloc(fs_info, flags, &tm); - if (ret <= 0) - return ret; + if (ret < 0) + goto out; tm->index = eb->start >> PAGE_CACHE_SHIFT; tm->slot = src_slot; @@ -571,10 +619,26 @@ tree_mod_log_insert_move(struct btrfs_fs_info *fs_info, tm->op = MOD_LOG_MOVE_KEYS; ret = __tree_mod_log_insert(fs_info, tm); - spin_unlock(&fs_info->tree_mod_seq_lock); +out: + tree_mod_log_write_unlock(fs_info); return ret; } +static inline void +__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb) +{ + int i; + u32 nritems; + int ret; + + nritems = btrfs_header_nritems(eb); + for (i = nritems - 1; i >= 0; i--) { + ret = tree_mod_log_insert_key_locked(fs_info, eb, i, + MOD_LOG_KEY_REMOVE_WHILE_FREEING); + BUG_ON(ret < 0); + } +} + static noinline int tree_mod_log_insert_root(struct btrfs_fs_info *fs_info, struct extent_buffer *old_root, @@ -583,9 +647,14 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm; int ret; + if (tree_mod_dont_log(fs_info, NULL)) + return 0; + + __tree_mod_log_free_eb(fs_info, old_root); + ret = tree_mod_alloc(fs_info, flags, &tm); - if (ret <= 0) - return ret; + if (ret < 0) + goto out; tm->index = new_root->start >> PAGE_CACHE_SHIFT; tm->old_root.logical = old_root->start; @@ -594,7 +663,8 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info, tm->op = MOD_LOG_ROOT_REPLACE; ret = __tree_mod_log_insert(fs_info, tm); - spin_unlock(&fs_info->tree_mod_seq_lock); +out: + tree_mod_log_write_unlock(fs_info); return ret; } @@ -608,7 +678,7 @@ __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq, struct tree_mod_elem *found = NULL; u64 index = start >> PAGE_CACHE_SHIFT; - read_lock(&fs_info->tree_mod_log_lock); + tree_mod_log_read_lock(fs_info); tm_root = &fs_info->tree_mod_log; node = tm_root->rb_node; while (node) { @@ -617,18 +687,18 @@ __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq, node = node->rb_left; } else if (cur->index > index) { node = node->rb_right; - } else if (cur->elem.seq < min_seq) { + } else if (cur->seq < min_seq) { node = node->rb_left; } else if (!smallest) { /* we want the node with the highest seq */ if (found) - BUG_ON(found->elem.seq > cur->elem.seq); + BUG_ON(found->seq > cur->seq); found = cur; node = node->rb_left; - } else if (cur->elem.seq > min_seq) { + } else if (cur->seq > min_seq) { /* we want the node with the smallest seq */ if (found) - BUG_ON(found->elem.seq < cur->elem.seq); + BUG_ON(found->seq < cur->seq); found = cur; node = node->rb_right; } else { @@ -636,7 +706,7 @@ __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq, break; } } - read_unlock(&fs_info->tree_mod_log_lock); + tree_mod_log_read_unlock(fs_info); return found; } @@ -664,7 +734,7 @@ tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq) return __tree_mod_log_search(fs_info, start, min_seq, 0); } -static inline void +static noinline void tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst, struct extent_buffer *src, unsigned long dst_offset, unsigned long src_offset, int nr_items) @@ -675,18 +745,23 @@ tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst, if (tree_mod_dont_log(fs_info, NULL)) return; - if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0) + if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0) { + tree_mod_log_write_unlock(fs_info); return; + } - /* speed this up by single seq for all operations? */ for (i = 0; i < nr_items; i++) { - ret = tree_mod_log_insert_key(fs_info, src, i + src_offset, - MOD_LOG_KEY_REMOVE); + ret = tree_mod_log_insert_key_locked(fs_info, src, + i + src_offset, + MOD_LOG_KEY_REMOVE); BUG_ON(ret < 0); - ret = tree_mod_log_insert_key(fs_info, dst, i + dst_offset, - MOD_LOG_KEY_ADD); + ret = tree_mod_log_insert_key_locked(fs_info, dst, + i + dst_offset, + MOD_LOG_KEY_ADD); BUG_ON(ret < 0); } + + tree_mod_log_write_unlock(fs_info); } static inline void @@ -699,7 +774,7 @@ tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst, BUG_ON(ret < 0); } -static inline void +static noinline void tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, struct btrfs_disk_key *disk_key, int slot, int atomic) @@ -712,30 +787,22 @@ tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info, BUG_ON(ret < 0); } -static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, - struct extent_buffer *eb) +static noinline void +tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb) { - int i; - int ret; - u32 nritems; - if (tree_mod_dont_log(fs_info, eb)) return; - nritems = btrfs_header_nritems(eb); - for (i = nritems - 1; i >= 0; i--) { - ret = tree_mod_log_insert_key(fs_info, eb, i, - MOD_LOG_KEY_REMOVE_WHILE_FREEING); - BUG_ON(ret < 0); - } + __tree_mod_log_free_eb(fs_info, eb); + + tree_mod_log_write_unlock(fs_info); } -static inline void +static noinline void tree_mod_log_set_root_pointer(struct btrfs_root *root, struct extent_buffer *new_root_node) { int ret; - tree_mod_log_free_eb(root->fs_info, root->node); ret = tree_mod_log_insert_root(root->fs_info, root->node, new_root_node, GFP_NOFS); BUG_ON(ret < 0); @@ -1069,7 +1136,7 @@ __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq, unsigned long p_size = sizeof(struct btrfs_key_ptr); n = btrfs_header_nritems(eb); - while (tm && tm->elem.seq >= time_seq) { + while (tm && tm->seq >= time_seq) { /* * all the operations are recorded with the operator used for * the modification. as we're going backwards, we do the -- cgit v1.2.3 From 2f38b3e1900634e64a186873b3388b1bf85dabc0 Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Tue, 13 Sep 2011 11:18:10 +0200 Subject: Btrfs: add helper for tree enumeration Often no exact match is wanted but just the next lower or higher item. There's a lot of duplicated code throughout btrfs to deal with the corner cases. This patch adds a helper function that can facilitate searching. Signed-off-by: Arne Jansen --- fs/btrfs/ctree.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index bef68ab32204..fb21431fe4e0 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2788,6 +2788,78 @@ done: return ret; } +/* + * helper to use instead of search slot if no exact match is needed but + * instead the next or previous item should be returned. + * When find_higher is true, the next higher item is returned, the next lower + * otherwise. + * When return_any and find_higher are both true, and no higher item is found, + * return the next lower instead. + * When return_any is true and find_higher is false, and no lower item is found, + * return the next higher instead. + * It returns 0 if any item is found, 1 if none is found (tree empty), and + * < 0 on error + */ +int btrfs_search_slot_for_read(struct btrfs_root *root, + struct btrfs_key *key, struct btrfs_path *p, + int find_higher, int return_any) +{ + int ret; + struct extent_buffer *leaf; + +again: + ret = btrfs_search_slot(NULL, root, key, p, 0, 0); + if (ret <= 0) + return ret; + /* + * a return value of 1 means the path is at the position where the + * item should be inserted. Normally this is the next bigger item, + * but in case the previous item is the last in a leaf, path points + * to the first free slot in the previous leaf, i.e. at an invalid + * item. + */ + leaf = p->nodes[0]; + + if (find_higher) { + if (p->slots[0] >= btrfs_header_nritems(leaf)) { + ret = btrfs_next_leaf(root, p); + if (ret <= 0) + return ret; + if (!return_any) + return 1; + /* + * no higher item found, return the next + * lower instead + */ + return_any = 0; + find_higher = 0; + btrfs_release_path(p); + goto again; + } + } else { + if (p->slots[0] >= btrfs_header_nritems(leaf)) { + /* we're sitting on an invalid slot */ + if (p->slots[0] == 0) { + ret = btrfs_prev_leaf(root, p); + if (ret <= 0) + return ret; + if (!return_any) + return 1; + /* + * no lower item found, return the next + * higher instead + */ + return_any = 0; + find_higher = 1; + btrfs_release_path(p); + goto again; + } + --p->slots[0]; + } + } + return 0; +} + /* * adjust the pointers going up the tree, starting at level * making sure the right key of each node is points to 'key'. -- cgit v1.2.3 From e679376911d016b670c8cfc1645c178f77e8d1d3 Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Tue, 13 Sep 2011 11:18:10 +0200 Subject: Btrfs: add helper for tree enumeration Often no exact match is wanted but just the next lower or higher item. There's a lot of duplicated code throughout btrfs to deal with the corner cases. This patch adds a helper function that can facilitate searching. Signed-off-by: Arne Jansen --- fs/btrfs/ctree.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 8206b3900587..c82a9e4a953e 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2721,6 +2721,80 @@ done: return ret; } +/* + * helper to use instead of search slot if no exact match is needed but + * instead the next or previous item should be returned. + * When find_higher is true, the next higher item is returned, the next lower + * otherwise. + * When return_any and find_higher are both true, and no higher item is found, + * return the next lower instead. + * When return_any is true and find_higher is false, and no lower item is found, + * return the next higher instead. + * It returns 0 if any item is found, 1 if none is found (tree empty), and + * < 0 on error + */ +int btrfs_search_slot_for_read(struct btrfs_root *root, + struct btrfs_key *key, struct btrfs_path *p, + int find_higher, int return_any) +{ + int ret; + struct extent_buffer *leaf; + +again: + ret = btrfs_search_slot(NULL, root, key, p, 0, 0); + if (ret <= 0) + return ret; + /* + * a return value of 1 means the path is at the position where the + * item should be inserted. Normally this is the next bigger item, + * but in case the previous item is the last in a leaf, path points + * to the first free slot in the previous leaf, i.e. at an invalid + * item. + */ + leaf = p->nodes[0]; + + if (find_higher) { + if (p->slots[0] >= btrfs_header_nritems(leaf)) { + ret = btrfs_next_leaf(root, p); + if (ret <= 0) + return ret; + if (!return_any) + return 1; + /* + * no higher item found, return the next + * lower instead + */ + return_any = 0; + find_higher = 0; + btrfs_release_path(p); + goto again; + } + } else { + if (p->slots[0] == 0) { + ret = btrfs_prev_leaf(root, p); + if (ret < 0) + return ret; + if (!ret) { + p->slots[0] = btrfs_header_nritems(leaf) - 1; + return 0; + } + if (!return_any) + return 1; + /* + * no lower item found, return the next + * higher instead + */ + return_any = 0; + find_higher = 1; + btrfs_release_path(p); + goto again; + } else { + --p->slots[0]; + } + } + return 0; +} + /* * adjust the pointers going up the tree, starting at level * making sure the right key of each node is points to 'key'. -- cgit v1.2.3 From 7069830a9e381e33d44ded45095f764844c71d24 Mon Sep 17 00:00:00 2001 From: Alexander Block Date: Tue, 5 Jun 2012 21:07:48 +0200 Subject: Btrfs: add btrfs_compare_trees function This function is used to find the differences between two trees. The tree compare skips whole subtrees if it detects shared tree blocks and thus is pretty fast. Signed-off-by: Alexander Block Reviewed-by: David Sterba Reviewed-by: Arne Jansen Reviewed-by: Jan Schmidt Reviewed-by: Alex Lyakas --- fs/btrfs/ctree.c | 425 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 425 insertions(+) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index c82a9e4a953e..4c10fd19d481 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5005,6 +5005,431 @@ out: return ret; } +static void tree_move_down(struct btrfs_root *root, + struct btrfs_path *path, + int *level, int root_level) +{ + path->nodes[*level - 1] = read_node_slot(root, path->nodes[*level], + path->slots[*level]); + path->slots[*level - 1] = 0; + (*level)--; +} + +static int tree_move_next_or_upnext(struct btrfs_root *root, + struct btrfs_path *path, + int *level, int root_level) +{ + int ret = 0; + int nritems; + nritems = btrfs_header_nritems(path->nodes[*level]); + + path->slots[*level]++; + + while (path->slots[*level] == nritems) { + if (*level == root_level) + return -1; + + /* move upnext */ + path->slots[*level] = 0; + free_extent_buffer(path->nodes[*level]); + path->nodes[*level] = NULL; + (*level)++; + path->slots[*level]++; + + nritems = btrfs_header_nritems(path->nodes[*level]); + ret = 1; + } + return ret; +} + +/* + * Returns 1 if it had to move up and next. 0 is returned if it moved only next + * or down. + */ +static int tree_advance(struct btrfs_root *root, + struct btrfs_path *path, + int *level, int root_level, + int allow_down, + struct btrfs_key *key) +{ + int ret; + + if (*level == 0 || !allow_down) { + ret = tree_move_next_or_upnext(root, path, level, root_level); + } else { + tree_move_down(root, path, level, root_level); + ret = 0; + } + if (ret >= 0) { + if (*level == 0) + btrfs_item_key_to_cpu(path->nodes[*level], key, + path->slots[*level]); + else + btrfs_node_key_to_cpu(path->nodes[*level], key, + path->slots[*level]); + } + return ret; +} + +static int tree_compare_item(struct btrfs_root *left_root, + struct btrfs_path *left_path, + struct btrfs_path *right_path, + char *tmp_buf) +{ + int cmp; + int len1, len2; + unsigned long off1, off2; + + len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]); + len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]); + if (len1 != len2) + return 1; + + off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]); + off2 = btrfs_item_ptr_offset(right_path->nodes[0], + right_path->slots[0]); + + read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1); + + cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1); + if (cmp) + return 1; + return 0; +} + +#define ADVANCE 1 +#define ADVANCE_ONLY_NEXT -1 + +/* + * This function compares two trees and calls the provided callback for + * every changed/new/deleted item it finds. + * If shared tree blocks are encountered, whole subtrees are skipped, making + * the compare pretty fast on snapshotted subvolumes. + * + * This currently works on commit roots only. As commit roots are read only, + * we don't do any locking. The commit roots are protected with transactions. + * Transactions are ended and rejoined when a commit is tried in between. + * + * This function checks for modifications done to the trees while comparing. + * If it detects a change, it aborts immediately. + */ +int btrfs_compare_trees(struct btrfs_root *left_root, + struct btrfs_root *right_root, + btrfs_changed_cb_t changed_cb, void *ctx) +{ + int ret; + int cmp; + struct btrfs_trans_handle *trans = NULL; + struct btrfs_path *left_path = NULL; + struct btrfs_path *right_path = NULL; + struct btrfs_key left_key; + struct btrfs_key right_key; + char *tmp_buf = NULL; + int left_root_level; + int right_root_level; + int left_level; + int right_level; + int left_end_reached; + int right_end_reached; + int advance_left; + int advance_right; + u64 left_blockptr; + u64 right_blockptr; + u64 left_start_ctransid; + u64 right_start_ctransid; + u64 ctransid; + + left_path = btrfs_alloc_path(); + if (!left_path) { + ret = -ENOMEM; + goto out; + } + right_path = btrfs_alloc_path(); + if (!right_path) { + ret = -ENOMEM; + goto out; + } + + tmp_buf = kmalloc(left_root->leafsize, GFP_NOFS); + if (!tmp_buf) { + ret = -ENOMEM; + goto out; + } + + left_path->search_commit_root = 1; + left_path->skip_locking = 1; + right_path->search_commit_root = 1; + right_path->skip_locking = 1; + + spin_lock(&left_root->root_times_lock); + left_start_ctransid = btrfs_root_ctransid(&left_root->root_item); + spin_unlock(&left_root->root_times_lock); + + spin_lock(&right_root->root_times_lock); + right_start_ctransid = btrfs_root_ctransid(&right_root->root_item); + spin_unlock(&right_root->root_times_lock); + + trans = btrfs_join_transaction(left_root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + trans = NULL; + goto out; + } + + /* + * Strategy: Go to the first items of both trees. Then do + * + * If both trees are at level 0 + * Compare keys of current items + * If left < right treat left item as new, advance left tree + * and repeat + * If left > right treat right item as deleted, advance right tree + * and repeat + * If left == right do deep compare of items, treat as changed if + * needed, advance both trees and repeat + * If both trees are at the same level but not at level 0 + * Compare keys of current nodes/leafs + * If left < right advance left tree and repeat + * If left > right advance right tree and repeat + * If left == right compare blockptrs of the next nodes/leafs + * If they match advance both trees but stay at the same level + * and repeat + * If they don't match advance both trees while allowing to go + * deeper and repeat + * If tree levels are different + * Advance the tree that needs it and repeat + * + * Advancing a tree means: + * If we are at level 0, try to go to the next slot. If that's not + * possible, go one level up and repeat. Stop when we found a level + * where we could go to the next slot. We may at this point be on a + * node or a leaf. + * + * If we are not at level 0 and not on shared tree blocks, go one + * level deeper. + * + * If we are not at level 0 and on shared tree blocks, go one slot to + * the right if possible or go up and right. + */ + + left_level = btrfs_header_level(left_root->commit_root); + left_root_level = left_level; + left_path->nodes[left_level] = left_root->commit_root; + extent_buffer_get(left_path->nodes[left_level]); + + right_level = btrfs_header_level(right_root->commit_root); + right_root_level = right_level; + right_path->nodes[right_level] = right_root->commit_root; + extent_buffer_get(right_path->nodes[right_level]); + + if (left_level == 0) + btrfs_item_key_to_cpu(left_path->nodes[left_level], + &left_key, left_path->slots[left_level]); + else + btrfs_node_key_to_cpu(left_path->nodes[left_level], + &left_key, left_path->slots[left_level]); + if (right_level == 0) + btrfs_item_key_to_cpu(right_path->nodes[right_level], + &right_key, right_path->slots[right_level]); + else + btrfs_node_key_to_cpu(right_path->nodes[right_level], + &right_key, right_path->slots[right_level]); + + left_end_reached = right_end_reached = 0; + advance_left = advance_right = 0; + + while (1) { + /* + * We need to make sure the transaction does not get committed + * while we do anything on commit roots. This means, we need to + * join and leave transactions for every item that we process. + */ + if (trans && btrfs_should_end_transaction(trans, left_root)) { + btrfs_release_path(left_path); + btrfs_release_path(right_path); + + ret = btrfs_end_transaction(trans, left_root); + trans = NULL; + if (ret < 0) + goto out; + } + /* now rejoin the transaction */ + if (!trans) { + trans = btrfs_join_transaction(left_root); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + trans = NULL; + goto out; + } + + spin_lock(&left_root->root_times_lock); + ctransid = btrfs_root_ctransid(&left_root->root_item); + spin_unlock(&left_root->root_times_lock); + if (ctransid != left_start_ctransid) + left_start_ctransid = 0; + + spin_lock(&right_root->root_times_lock); + ctransid = btrfs_root_ctransid(&right_root->root_item); + spin_unlock(&right_root->root_times_lock); + if (ctransid != right_start_ctransid) + right_start_ctransid = 0; + + if (!left_start_ctransid || !right_start_ctransid) { + WARN(1, KERN_WARNING + "btrfs: btrfs_compare_tree detected " + "a change in one of the trees while " + "iterating. This is probably a " + "bug.\n"); + ret = -EIO; + goto out; + } + + /* + * the commit root may have changed, so start again + * where we stopped + */ + left_path->lowest_level = left_level; + right_path->lowest_level = right_level; + ret = btrfs_search_slot(NULL, left_root, + &left_key, left_path, 0, 0); + if (ret < 0) + goto out; + ret = btrfs_search_slot(NULL, right_root, + &right_key, right_path, 0, 0); + if (ret < 0) + goto out; + } + + if (advance_left && !left_end_reached) { + ret = tree_advance(left_root, left_path, &left_level, + left_root_level, + advance_left != ADVANCE_ONLY_NEXT, + &left_key); + if (ret < 0) + left_end_reached = ADVANCE; + advance_left = 0; + } + if (advance_right && !right_end_reached) { + ret = tree_advance(right_root, right_path, &right_level, + right_root_level, + advance_right != ADVANCE_ONLY_NEXT, + &right_key); + if (ret < 0) + right_end_reached = ADVANCE; + advance_right = 0; + } + + if (left_end_reached && right_end_reached) { + ret = 0; + goto out; + } else if (left_end_reached) { + if (right_level == 0) { + ret = changed_cb(left_root, right_root, + left_path, right_path, + &right_key, + BTRFS_COMPARE_TREE_DELETED, + ctx); + if (ret < 0) + goto out; + } + advance_right = ADVANCE; + continue; + } else if (right_end_reached) { + if (left_level == 0) { + ret = changed_cb(left_root, right_root, + left_path, right_path, + &left_key, + BTRFS_COMPARE_TREE_NEW, + ctx); + if (ret < 0) + goto out; + } + advance_left = ADVANCE; + continue; + } + + if (left_level == 0 && right_level == 0) { + cmp = btrfs_comp_cpu_keys(&left_key, &right_key); + if (cmp < 0) { + ret = changed_cb(left_root, right_root, + left_path, right_path, + &left_key, + BTRFS_COMPARE_TREE_NEW, + ctx); + if (ret < 0) + goto out; + advance_left = ADVANCE; + } else if (cmp > 0) { + ret = changed_cb(left_root, right_root, + left_path, right_path, + &right_key, + BTRFS_COMPARE_TREE_DELETED, + ctx); + if (ret < 0) + goto out; + advance_right = ADVANCE; + } else { + ret = tree_compare_item(left_root, left_path, + right_path, tmp_buf); + if (ret) { + ret = changed_cb(left_root, right_root, + left_path, right_path, + &left_key, + BTRFS_COMPARE_TREE_CHANGED, + ctx); + if (ret < 0) + goto out; + } + advance_left = ADVANCE; + advance_right = ADVANCE; + } + } else if (left_level == right_level) { + cmp = btrfs_comp_cpu_keys(&left_key, &right_key); + if (cmp < 0) { + advance_left = ADVANCE; + } else if (cmp > 0) { + advance_right = ADVANCE; + } else { + left_blockptr = btrfs_node_blockptr( + left_path->nodes[left_level], + left_path->slots[left_level]); + right_blockptr = btrfs_node_blockptr( + right_path->nodes[right_level], + right_path->slots[right_level]); + if (left_blockptr == right_blockptr) { + /* + * As we're on a shared block, don't + * allow to go deeper. + */ + advance_left = ADVANCE_ONLY_NEXT; + advance_right = ADVANCE_ONLY_NEXT; + } else { + advance_left = ADVANCE; + advance_right = ADVANCE; + } + } + } else if (left_level < right_level) { + advance_right = ADVANCE; + } else { + advance_left = ADVANCE; + } + } + +out: + btrfs_free_path(left_path); + btrfs_free_path(right_path); + kfree(tmp_buf); + + if (trans) { + if (!ret) + ret = btrfs_end_transaction(trans, left_root); + else + btrfs_end_transaction(trans, left_root); + } + + return ret; +} + /* * this is similar to btrfs_next_leaf, but does not try to preserve * and fixup the path. It looks for and returns the next key in the -- cgit v1.2.3