From f617e2fd52484fb74236a597d0f9068ec7d9d2dd Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Thu, 14 Jun 2012 16:10:13 +0200 Subject: Btrfs: remove obsolete btrfs_next_leaf call from __resolve_indirect_ref When resolving indirect refs, we used to call btrfs_next_leaf in case we didn't find an exact match. While we should find exact matches most of the time, in case we don't, we must continue searching. Treating those matches differently depending on the level we're searching doesn't make sense. Even worse, we might end up searching for a key larger than the largest, in which case there is no next_leaf and subsequent jobs would fail. This commit drops the bogous lines. Signed-off-by: Jan Schmidt --- fs/btrfs/backref.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) (limited to 'fs/btrfs/backref.c') diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 3f75895c919b..579131de1b3b 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -294,16 +294,8 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, goto out; } - if (level == 0) { - if (ret == 1 && path->slots[0] >= btrfs_header_nritems(eb)) { - ret = btrfs_next_leaf(root, path); - if (ret) - goto out; - eb = path->nodes[0]; - } - + if (level == 0) btrfs_item_key_to_cpu(eb, &key, path->slots[0]); - } ret = add_all_parents(root, path, parents, level, &key, ref->wanted_disk_byte, extent_item_pos); -- cgit From 3d7806eca43e73a9721d2e09369200ed93036bd0 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Mon, 11 Jun 2012 08:29:29 +0200 Subject: Btrfs: add btrfs_next_old_leaf To make sense of the tree mod log, the backref walker not only needs btrfs_search_old_slot, but it also called btrfs_next_leaf, which in turn was calling btrfs_search_slot. This obviously didn't give the correct result. This commit adds btrfs_next_old_leaf, a drop-in replacement for btrfs_next_leaf with a time_seq parameter. If it is zero, it behaves exactly like btrfs_next_leaf. If it is non-zero, it will use btrfs_search_old_slot with this time_seq parameter. Signed-off-by: Jan Schmidt --- fs/btrfs/backref.c | 7 ++++--- fs/btrfs/ctree.c | 11 ++++++++++- fs/btrfs/ctree.h | 2 ++ 3 files changed, 16 insertions(+), 4 deletions(-) (limited to 'fs/btrfs/backref.c') diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 579131de1b3b..8f7d1237b7a0 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -179,7 +179,8 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id, static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, struct ulist *parents, int level, - struct btrfs_key *key, u64 wanted_disk_byte, + struct btrfs_key *key, u64 time_seq, + u64 wanted_disk_byte, const u64 *extent_item_pos) { int ret; @@ -212,7 +213,7 @@ add_parent: */ while (1) { eie = NULL; - ret = btrfs_next_leaf(root, path); + ret = btrfs_next_old_leaf(root, path, time_seq); if (ret < 0) return ret; if (ret) @@ -297,7 +298,7 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, if (level == 0) btrfs_item_key_to_cpu(eb, &key, path->slots[0]); - ret = add_all_parents(root, path, parents, level, &key, + ret = add_all_parents(root, path, parents, level, &key, time_seq, ref->wanted_disk_byte, extent_item_pos); out: btrfs_free_path(path); diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 50d7c99ddce7..cb76b2a1b908 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5016,6 +5016,12 @@ next: * returns < 0 on io errors. */ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) +{ + return btrfs_next_old_leaf(root, path, 0); +} + +int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path, + u64 time_seq) { int slot; int level; @@ -5041,7 +5047,10 @@ again: path->keep_locks = 1; path->leave_spinning = 1; - ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (time_seq) + ret = btrfs_search_old_slot(root, &key, path, time_seq); + else + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); path->keep_locks = 0; if (ret < 0) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 0151ca1ac657..db15e9e7b91c 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -2753,6 +2753,8 @@ static inline int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, } int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path); +int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path, + u64 time_seq); static inline int btrfs_next_item(struct btrfs_root *root, struct btrfs_path *p) { ++p->slots[0]; -- cgit From 69bca40d41c613927b150c5392505f1894fe3010 Mon Sep 17 00:00:00 2001 From: Alexander Block Date: Tue, 19 Jun 2012 07:42:26 -0600 Subject: Btrfs: don't assume to be on the correct extent in add_all_parents add_all_parents did assume that path is already at a correct extent data item, which may not be true in case of data extents that were partly rewritten and splitted. We need to check if we're on a matching extent for every item and only for the ones after the first. The loop is changed to do this now. This patch also fixes a bug introduced with commit 3b127fd8 "Btrfs: remove obsolete btrfs_next_leaf call from __resolve_indirect_ref". The removal of next_leaf did sometimes result in slot==nritems when the above described case happens, and thus resulting in invalid values (e.g. wanted_obejctid) in add_all_parents (leading to missed backrefs or even crashes). Signed-off-by: Alexander Block Signed-off-by: Jan Schmidt Signed-off-by: Chris Mason --- fs/btrfs/backref.c | 94 ++++++++++++++++++++++++++++++------------------------ 1 file changed, 52 insertions(+), 42 deletions(-) (limited to 'fs/btrfs/backref.c') diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 8f7d1237b7a0..7301cdb4b2cb 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -179,61 +179,74 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id, static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, struct ulist *parents, int level, - struct btrfs_key *key, u64 time_seq, + struct btrfs_key *key_for_search, u64 time_seq, u64 wanted_disk_byte, const u64 *extent_item_pos) { - int ret; - int slot = path->slots[level]; - struct extent_buffer *eb = path->nodes[level]; + int ret = 0; + int slot; + struct extent_buffer *eb; + struct btrfs_key key; struct btrfs_file_extent_item *fi; struct extent_inode_elem *eie = NULL; u64 disk_byte; - u64 wanted_objectid = key->objectid; -add_parent: - if (level == 0 && extent_item_pos) { - fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); - ret = check_extent_in_eb(key, eb, fi, *extent_item_pos, &eie); + if (level != 0) { + eb = path->nodes[level]; + ret = ulist_add(parents, eb->start, 0, GFP_NOFS); if (ret < 0) return ret; - } - ret = ulist_add(parents, eb->start, (unsigned long)eie, GFP_NOFS); - if (ret < 0) - return ret; - - if (level != 0) return 0; + } /* - * if the current leaf is full with EXTENT_DATA items, we must - * check the next one if that holds a reference as well. - * ref->count cannot be used to skip this check. - * repeat this until we don't find any additional EXTENT_DATA items. + * We normally enter this function with the path already pointing to + * the first item to check. But sometimes, we may enter it with + * slot==nritems. In that case, go to the next leaf before we continue. */ - while (1) { - eie = NULL; + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) ret = btrfs_next_old_leaf(root, path, time_seq); - if (ret < 0) - return ret; - if (ret) - return 0; + while (!ret) { eb = path->nodes[0]; - for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) { - btrfs_item_key_to_cpu(eb, key, slot); - if (key->objectid != wanted_objectid || - key->type != BTRFS_EXTENT_DATA_KEY) - return 0; - fi = btrfs_item_ptr(eb, slot, - struct btrfs_file_extent_item); - disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); - if (disk_byte == wanted_disk_byte) - goto add_parent; + slot = path->slots[0]; + + btrfs_item_key_to_cpu(eb, &key, slot); + + if (key.objectid != key_for_search->objectid || + key.type != BTRFS_EXTENT_DATA_KEY) + break; + + fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); + + if (disk_byte == wanted_disk_byte) { + eie = NULL; + if (extent_item_pos) { + ret = check_extent_in_eb(&key, eb, fi, + *extent_item_pos, + &eie); + if (ret < 0) + break; + } + if (!ret) { + ret = ulist_add(parents, eb->start, + (unsigned long)eie, GFP_NOFS); + if (ret < 0) + break; + if (!extent_item_pos) { + ret = btrfs_next_old_leaf(root, path, + time_seq); + continue; + } + } } + ret = btrfs_next_old_item(root, path, time_seq); } - return 0; + if (ret > 0) + ret = 0; + return ret; } /* @@ -250,7 +263,6 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, struct btrfs_path *path; struct btrfs_root *root; struct btrfs_key root_key; - struct btrfs_key key = {0}; struct extent_buffer *eb; int ret = 0; int root_level; @@ -295,11 +307,9 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, goto out; } - if (level == 0) - btrfs_item_key_to_cpu(eb, &key, path->slots[0]); - - ret = add_all_parents(root, path, parents, level, &key, time_seq, - ref->wanted_disk_byte, extent_item_pos); + ret = add_all_parents(root, path, parents, level, &ref->key_for_search, + time_seq, ref->wanted_disk_byte, + extent_item_pos); out: btrfs_free_path(path); return ret; -- cgit