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
