None of the uses of btrfs_search_forward() need to have the path nodes (level >= 1) read locked, only the leaf needs to be locked while the caller processes it. Therefore make it return a path with all nodes unlocked, except for the leaf.
This change is motivated by the observation that during a file fsync we repeatdly call btrfs_search_forward() and process the returned leaf while upper nodes of the returned path (level >= 1) are read locked, which unnecessarily blocks other tasks that want to write to the same fs/subvol btree. Therefore instead of modifying the fsync code to unlock all nodes with level >= 1 immediately after calling btrfs_search_forward(), change btrfs_search_forward() to do it, so that it benefits all callers. Signed-off-by: Filipe Manana <[email protected]> --- fs/btrfs/ctree.c | 11 +++++++---- fs/btrfs/ioctl.c | 5 ----- fs/btrfs/tree-log.c | 3 --- fs/btrfs/uuid-tree.c | 1 - fs/btrfs/volumes.c | 2 -- 5 files changed, 7 insertions(+), 15 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 8ca6761..993d81b 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5144,8 +5144,9 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, u32 nritems; int level; int ret = 1; + int keep_locks = path->keep_locks; - WARN_ON(!path->keep_locks); + path->keep_locks = 1; again: cur = btrfs_read_lock_root_node(root); level = btrfs_header_level(cur); @@ -5209,7 +5210,6 @@ find_next_key: path->slots[level] = slot; if (level == path->lowest_level) { ret = 0; - unlock_up(path, level, 1, 0, NULL); goto out; } btrfs_set_path_blocking(path); @@ -5224,9 +5224,12 @@ find_next_key: btrfs_clear_path_blocking(path, NULL, 0); } out: - if (ret == 0) + path->keep_locks = keep_locks; + if (ret == 0) { + btrfs_unlock_up_safe(path, path->lowest_level + 1); + btrfs_set_path_blocking(path); memcpy(min_key, &found_key, sizeof(found_key)); - btrfs_set_path_blocking(path); + } return ret; } diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index ef2e073..d490abd 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -936,12 +936,9 @@ static int find_new_extents(struct btrfs_root *root, min_key.offset = *off; while (1) { - path->keep_locks = 1; ret = btrfs_search_forward(root, &min_key, path, newer_than); if (ret != 0) goto none; - path->keep_locks = 0; - btrfs_unlock_up_safe(path, 1); process_slot: if (min_key.objectid != ino) goto none; @@ -2083,8 +2080,6 @@ static noinline int search_ioctl(struct inode *inode, key.type = sk->min_type; key.offset = sk->min_offset; - path->keep_locks = 1; - while (1) { ret = btrfs_search_forward(root, &key, path, sk->min_transid); if (ret != 0) { diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 6e0fa17..df332dd 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -2981,8 +2981,6 @@ static noinline int log_dir_items(struct btrfs_trans_handle *trans, min_key.type = key_type; min_key.offset = min_offset; - path->keep_locks = 1; - ret = btrfs_search_forward(root, &min_key, path, trans->transid); /* @@ -3950,7 +3948,6 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans, err = ret; goto out_unlock; } - path->keep_locks = 1; while (1) { ins_nr = 0; diff --git a/fs/btrfs/uuid-tree.c b/fs/btrfs/uuid-tree.c index f6a4c03..7782829 100644 --- a/fs/btrfs/uuid-tree.c +++ b/fs/btrfs/uuid-tree.c @@ -279,7 +279,6 @@ int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info, key.offset = 0; again_search_slot: - path->keep_locks = 1; ret = btrfs_search_forward(root, &key, path, 0); if (ret) { if (ret > 0) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 0daf748..73e4d30 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3629,8 +3629,6 @@ static int btrfs_uuid_scan_kthread(void *data) max_key.type = BTRFS_ROOT_ITEM_KEY; max_key.offset = (u64)-1; - path->keep_locks = 1; - while (1) { ret = btrfs_search_forward(root, &key, path, 0); if (ret) { -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
