btrfs: do reverse path readahead in btrfs_shrink_device
In btrfs_shrink_device, before btrfs_search_slot, path->reada is set to
READA_FORWARD. But I think READA_BACK is correct.
Since:
1. key.offset is set to (u64)-1
2. after btrfs_search_slot, btrfs_previous_item is called
So, for readahead previous items, READA_BACK is the correct one.
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7b3b235..78f6cd1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4414,7 +4414,7 @@
if (!path)
return -ENOMEM;
- path->reada = READA_FORWARD;
+ path->reada = READA_BACK;
mutex_lock(&fs_info->chunk_mutex);