[PATCH 3/3] ext4: Find desired extent in ext4_ext_shift_extents() using binsearch

From: Roman Pen
Date: Mon Jan 02 2017 - 07:55:18 EST


The aim of this patch is to optimize a search of an extent while
doing right shift using binsearch.

Cc: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
fs/ext4/extents.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 9fbf92ca358c..f65cc2762780 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5433,10 +5433,15 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
else
/* Beginning is reached, end of the loop */
iterator = NULL;
- /* Update path extent in case we need to stop */
- while (le32_to_cpu(extent->ee_block) < start)
- extent++;
- path[depth].p_ext = extent;
+ if (le32_to_cpu(extent->ee_block) < start)
+ /*
+ * Desired extent is somewhere in the middle,
+ * do binsearch and update a path with it.
+ */
+ ext4_ext_binsearch(inode, &path[depth], start);
+ else
+ /* Set the first extent */
+ path[depth].p_ext = extent;
}
ret = ext4_ext_shift_path_extents(path, shift, inode,
handle, SHIFT);
--
2.10.2