[PATCH 2/3] btrfs: defrag: use extent_thresh to replace the hardcoded size limit

[Qu Wenruo <wqu@suse.com>]

In defrag_lookup_extent() we use hardcoded extent size threshold, SZ_128K,
other than @extent_thresh in btrfs_defrag_file().

This can lead to some inconsistent behavior, especially the default
extent size threshold is 256K.

Fix this by passing @extent_thresh into defrag_check_next_extent() and
use that value.

Also, since the extent_thresh check should be applied to all extents,
not only physically adjacent extents, move the threshold check into a
dedicate if ().

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/ioctl.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0d8bfc716e6b..2911df12fc48 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1050,7 +1050,7 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
 }
 
 static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
-				     bool locked)
+				     u32 extent_thresh, bool locked)
 {
 	struct extent_map *next;
 	bool ret = false;
@@ -1066,9 +1066,11 @@ static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
 	/* Preallocated */
 	if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
 		goto out;
-	/* Physically adjacent and large enough */
-	if ((em->block_start + em->block_len == next->block_start) &&
-	    (em->block_len > SZ_128K && next->block_len > SZ_128K))
+	/* Extent is already large enough */
+	if (next->len >= extent_thresh)
+		goto out;
+	/* Physically adjacent */
+	if ((em->block_start + em->block_len == next->block_start))
 		goto out;
 	ret = true;
 out:
@@ -1231,7 +1233,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 			goto next;
 
 		next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
-							  locked);
+							  extent_thresh, locked);
 		if (!next_mergeable) {
 			struct defrag_target_range *last;
 
-- 
2.34.1