Btrfs: allow compressed extents to be merged during defragment

The rule originally comes from nocow writing, but snapshot-aware
defrag is a different case, the extent has been writen and we're
not going to change the extent but add a reference on the data.

So we're able to allow such compressed extents to be merged into
one bigger extent if they're pointing to the same data.

Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 27fa81977f86..66571dce88d1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2212,16 +2212,18 @@ static noinline bool record_extent_backrefs(struct btrfs_path *path,
 
 static int relink_is_mergable(struct extent_buffer *leaf,
                               struct btrfs_file_extent_item *fi,
-                              u64 disk_bytenr)
+                              struct new_sa_defrag_extent *new)
 {
-        if (btrfs_file_extent_disk_bytenr(leaf, fi) != disk_bytenr)
+        if (btrfs_file_extent_disk_bytenr(leaf, fi) != new->bytenr)
                 return 0;
 
         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
                 return 0;
 
-        if (btrfs_file_extent_compression(leaf, fi) ||
-            btrfs_file_extent_encryption(leaf, fi) ||
+        if (btrfs_file_extent_compression(leaf, fi) != new->compress_type)
+                return 0;
+
+        if (btrfs_file_extent_encryption(leaf, fi) ||
             btrfs_file_extent_other_encoding(leaf, fi))
                 return 0;
 
@@ -2365,8 +2367,8 @@ again:
                                     struct btrfs_file_extent_item);
                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
 
-                if (relink_is_mergable(leaf, fi, new->bytenr) &&
-                    extent_len + found_key.offset == start) {
+                if (extent_len + found_key.offset == start &&
+                    relink_is_mergable(leaf, fi, new)) {
                         btrfs_set_file_extent_num_bytes(leaf, fi,
                                                         extent_len + len);
                         btrfs_mark_buffer_dirty(leaf);