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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 <ablock84@googlemail.com> Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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parent
1c8f52a5e9
commit
69bca40d41
1 changed files with 52 additions and 42 deletions
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@ -179,61 +179,74 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
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static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
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struct ulist *parents, int level,
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struct btrfs_key *key, u64 time_seq,
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struct btrfs_key *key_for_search, u64 time_seq,
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u64 wanted_disk_byte,
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const u64 *extent_item_pos)
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{
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int ret;
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int slot = path->slots[level];
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struct extent_buffer *eb = path->nodes[level];
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int ret = 0;
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int slot;
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struct extent_buffer *eb;
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struct btrfs_key key;
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struct btrfs_file_extent_item *fi;
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struct extent_inode_elem *eie = NULL;
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u64 disk_byte;
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u64 wanted_objectid = key->objectid;
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add_parent:
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if (level == 0 && extent_item_pos) {
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fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
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ret = check_extent_in_eb(key, eb, fi, *extent_item_pos, &eie);
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if (level != 0) {
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eb = path->nodes[level];
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ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
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if (ret < 0)
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return ret;
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}
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ret = ulist_add(parents, eb->start, (unsigned long)eie, GFP_NOFS);
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if (ret < 0)
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return ret;
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if (level != 0)
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return 0;
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}
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/*
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* if the current leaf is full with EXTENT_DATA items, we must
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* check the next one if that holds a reference as well.
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* ref->count cannot be used to skip this check.
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* repeat this until we don't find any additional EXTENT_DATA items.
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* We normally enter this function with the path already pointing to
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* the first item to check. But sometimes, we may enter it with
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* slot==nritems. In that case, go to the next leaf before we continue.
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*/
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while (1) {
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eie = NULL;
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if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
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ret = btrfs_next_old_leaf(root, path, time_seq);
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if (ret < 0)
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return ret;
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if (ret)
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return 0;
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while (!ret) {
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eb = path->nodes[0];
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for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) {
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btrfs_item_key_to_cpu(eb, key, slot);
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if (key->objectid != wanted_objectid ||
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key->type != BTRFS_EXTENT_DATA_KEY)
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return 0;
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fi = btrfs_item_ptr(eb, slot,
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struct btrfs_file_extent_item);
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disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
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if (disk_byte == wanted_disk_byte)
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goto add_parent;
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slot = path->slots[0];
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btrfs_item_key_to_cpu(eb, &key, slot);
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if (key.objectid != key_for_search->objectid ||
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key.type != BTRFS_EXTENT_DATA_KEY)
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break;
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fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
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disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
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if (disk_byte == wanted_disk_byte) {
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eie = NULL;
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if (extent_item_pos) {
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ret = check_extent_in_eb(&key, eb, fi,
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*extent_item_pos,
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&eie);
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if (ret < 0)
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break;
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}
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if (!ret) {
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ret = ulist_add(parents, eb->start,
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(unsigned long)eie, GFP_NOFS);
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if (ret < 0)
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break;
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if (!extent_item_pos) {
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ret = btrfs_next_old_leaf(root, path,
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time_seq);
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continue;
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}
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}
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}
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ret = btrfs_next_old_item(root, path, time_seq);
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}
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return 0;
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if (ret > 0)
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ret = 0;
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return ret;
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}
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/*
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@ -250,7 +263,6 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
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struct btrfs_path *path;
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struct btrfs_root *root;
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struct btrfs_key root_key;
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struct btrfs_key key = {0};
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struct extent_buffer *eb;
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int ret = 0;
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int root_level;
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@ -295,11 +307,9 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
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goto out;
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}
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if (level == 0)
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btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
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ret = add_all_parents(root, path, parents, level, &key, time_seq,
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ref->wanted_disk_byte, extent_item_pos);
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ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
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time_seq, ref->wanted_disk_byte,
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extent_item_pos);
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out:
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btrfs_free_path(path);
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return ret;
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