Unless it's going to read inline extents from btree leaf to page, btrfs_get_extent won't sleep during the period of holding path lock.
This sets leave_spinning at first and sets path to blocking mode right before reading inline extent if that's the case. The benefit is that a path in spinning mode typically has less impact (faster) on waiters rather than that in blocking mode. Signed-off-by: Liu Bo <bo....@linux.alibaba.com> --- fs/btrfs/inode.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 10e86f7b5398..4219be9c21f9 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6843,6 +6843,12 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, */ path->reada = READA_FORWARD; + /* + * Unless we're going to uncompress inline extent, no sleep would + * happen. + */ + path->leave_spinning = 1; + ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0); if (ret < 0) { err = ret; @@ -6945,6 +6951,8 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, em->orig_block_len = em->len; em->orig_start = em->start; ptr = btrfs_file_extent_inline_start(item) + extent_offset; + + btrfs_set_path_blocking(path); if (!PageUptodate(page)) { if (btrfs_file_extent_compression(leaf, item) != BTRFS_COMPRESS_NONE) { @@ -6992,10 +7000,10 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, err = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len); write_unlock(&em_tree->lock); out: + btrfs_free_path(path); trace_btrfs_get_extent(root, inode, em); - btrfs_free_path(path); if (err) { free_extent_map(em); return ERR_PTR(err); -- 1.8.3.1