diff mbox

Btrfs: fix autodefrag with compression

Message ID 53FE28C0.4010603@fb.com (mailing list archive)
State Accepted
Headers show

Commit Message

Chris Mason Aug. 27, 2014, 6:51 p.m. UTC 
The autodefrag code skips defrag when two extents are adjacent.  But one
big advantage for autodefrag is cutting down on the number of small
extents, even when they are adjacent.  This commit changes it to defrag
all small extents.

This is especially useful when trying to use compression on slowly
growing log files.  We usually end up writing 4K or less at a time, so
the compression code isn't able to compress across multiple pages.

Signed-off-by: Chris Mason <clm@fb.com>
---
 fs/btrfs/ioctl.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

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diff mbox

Patch

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fce6fd0e..a018ea4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1019,8 +1019,10 @@  static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em)
 		return false;
 
 	next = defrag_lookup_extent(inode, em->start + em->len);
-	if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE ||
-	    (em->block_start + em->block_len == next->block_start))
+	if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
+		ret = false;
+	else if ((em->block_start + em->block_len == next->block_start) &&
+		 (em->block_len > 128 * 1024 && next->block_len > 128 * 1024))
 		ret = false;
 
 	free_extent_map(next);