Btrfs devel - Jun 2012 - [PATCH] Ignore unfragmented file checks in defrag when compression enabled

I noticed that btrfs fi defrag -c<method> can''t be used to
compress files
unless they are fragmented. This patch corrects the problem, by informing
should_defrag_range if compression is enabled, and skipping tests for extent
and adjacent extents if it is.

Andrew Mahone (1):
  btrfs: ignore unfragmented file checks in defrag when compression
    enabled

 fs/btrfs/ioctl.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

-- 
1.7.10.2

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Inform should_defrag_range if BTRFS_DEFRAG_RANGE_COMPRESS is set. If so, skip
checks for adjacent extents and extent size when deciding whether to defrag,
as these can prevent an uncompressed and unfragmented file from being
compressed as requested.

Signed-off-by: Andrew Mahone <andrew.mahone@gmail.com>
---
 fs/btrfs/ioctl.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 24b776c..ac48d7f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -812,7 +812,7 @@ static int check_adjacent_extents(struct inode *inode,
struct extent_map *em)
 
 static int should_defrag_range(struct inode *inode, u64 start, u64 len,
 			       int thresh, u64 *last_len, u64 *skip,
-			       u64 *defrag_end)
+			       u64 *defrag_end, int compress)
 {
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct extent_map *em = NULL;
@@ -853,7 +853,7 @@ static int should_defrag_range(struct inode *inode, u64
start, u64 len,
 	}
 
 	/* If we have nothing to merge with us, just skip. */
-	if (check_adjacent_extents(inode, em)) {
+	if (!compress && check_adjacent_extents(inode, em)) {
 		ret = 0;
 		goto out;
 	}
@@ -861,7 +861,8 @@ static int should_defrag_range(struct inode *inode, u64
start, u64 len,
 	/*
 	 * we hit a real extent, if it is big don''t bother defragging it
again
 	 */
-	if ((*last_len == 0 || *last_len >= thresh) && em->len >=
thresh)
+	if (!compress &&
+	    (*last_len == 0 || *last_len >= thresh) && em->len >=
thresh)
 		ret = 0;
 
 out:
@@ -1143,7 +1144,8 @@ int btrfs_defrag_file(struct inode *inode, struct file
*file,
 
 		if (!should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,
 					 PAGE_CACHE_SIZE, extent_thresh,
-					 &last_len, &skip, &defrag_end)) {
+					 &last_len, &skip, &defrag_end,
+					 range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
 			unsigned long next;
 			/*
 			 * the should_defrag function tells us how much to skip
-- 
1.7.10.2

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On Mon, Jun 18, 2012 at 01:27:37PM -0400, Andrew Mahone
wrote:
> Inform should_defrag_range if BTRFS_DEFRAG_RANGE_COMPRESS is set. If so,
skip
> checks for adjacent extents and extent size when deciding whether to
defrag,
> as these can prevent an uncompressed and unfragmented file from being
> compressed as requested.
> 
> Signed-off-by: Andrew Mahone <andrew.mahone@gmail.com>
This patch does not apply cleanly at all, please rebase onto btrfs-next and
resend.  Thanks,

Josef
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Rebased on btrfs-next and retested.

Inform should_defrag_range if BTRFS_DEFRAG_RANGE_COMPRESS is set. If so, skip
checks for adjacent extents and extent size when deciding whether to defrag,
as these can prevent an uncompressed and unfragmented file from being
compressed as requested.

Signed-off-by: Andrew Mahone <andrew.mahone@gmail.com>
---
 fs/btrfs/ioctl.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0e92e57..9ec23b9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -832,7 +832,8 @@ static bool defrag_check_next_extent(struct inode *inode,
struct extent_map *em)
 }
 
 static int should_defrag_range(struct inode *inode, u64 start, int thresh,
-			       u64 *last_len, u64 *skip, u64 *defrag_end)
+			       u64 *last_len, u64 *skip, u64 *defrag_end,
+			       int compress)
 {
 	struct extent_map *em;
 	int ret = 1;
@@ -863,7 +864,7 @@ static int should_defrag_range(struct inode *inode, u64
start, int thresh,
 	 * we hit a real extent, if it is big or the next extent is not a
 	 * real extent, don''t bother defragging it
 	 */
-	if ((*last_len == 0 || *last_len >= thresh) &&
+	if (!compress && (*last_len == 0 || *last_len >= thresh) &&
 	    (em->len >= thresh || !next_mergeable))
 		ret = 0;
 out:
@@ -1145,7 +1146,8 @@ int btrfs_defrag_file(struct inode *inode, struct file
*file,
 
 		if (!should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,
 					 extent_thresh, &last_len, &skip,
-					 &defrag_end)) {
+					 &defrag_end, range->flags &
+					 BTRFS_DEFRAG_RANGE_COMPRESS)) {
 			unsigned long next;
 			/*
 			 * the should_defrag function tells us how much to skip
-- 
1.7.10.4

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