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>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 27fa819..66571dc 100644 (file)
--- 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);