diff options
| -rw-r--r-- | fs/btrfs/ctree.c | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 8396079709c4..e1e942e1918f 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1409,12 +1409,21 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, struct btrfs_key first_key; int ret; int parent_level; + bool unlock_up; + unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]); blocknr = btrfs_node_blockptr(*eb_ret, slot); gen = btrfs_node_ptr_generation(*eb_ret, slot); parent_level = btrfs_header_level(*eb_ret); btrfs_node_key_to_cpu(*eb_ret, &first_key, slot); + /* + * If we need to read an extent buffer from disk and we are holding locks + * on upper level nodes, we unlock all the upper nodes before reading the + * extent buffer, and then return -EAGAIN to the caller as it needs to + * restart the search. We don't release the lock on the current level + * because we need to walk this node to figure out which blocks to read. + */ tmp = find_extent_buffer(fs_info, blocknr); if (tmp) { if (p->reada == READA_FORWARD_ALWAYS) @@ -1436,6 +1445,9 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, return 0; } + if (unlock_up) + btrfs_unlock_up_safe(p, level + 1); + /* now we're allowed to do a blocking uptodate check */ ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key); if (ret) { @@ -1443,17 +1455,14 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, btrfs_release_path(p); return -EIO; } - *eb_ret = tmp; - return 0; + + if (unlock_up) + ret = -EAGAIN; + + goto out; } - if ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]) { - /* - * Reduce lock contention at high levels of the btree by - * dropping locks before we read. Don't release the lock - * on the current level because we need to walk this node - * to figure out which blocks to read. - */ + if (unlock_up) { btrfs_unlock_up_safe(p, level + 1); ret = -EAGAIN; } else { @@ -1478,6 +1487,7 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, if (!extent_buffer_uptodate(tmp)) ret = -EIO; +out: if (ret == 0) { *eb_ret = tmp; } else { |