btrfs: use fs_info->max_extent_size in get_extent_max_capacity()

Use fs_info->max_extent_size also in get_extent_max_capacity() for the
completeness. This is only used for defrag and not really necessary to fix
the metadata reservation size. But, it still suppresses unnecessary defrag
operations.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -1230,16 +1230,18 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
 	return em;
 }
 
-static u32 get_extent_max_capacity(const struct extent_map *em)
+static u32 get_extent_max_capacity(const struct btrfs_fs_info *fs_info,
+				   const struct extent_map *em)
 {
 	if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
 		return BTRFS_MAX_COMPRESSED;
-	return BTRFS_MAX_EXTENT_SIZE;
+	return fs_info->max_extent_size;
 }
 
 static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
 				     u32 extent_thresh, u64 newer_than, bool locked)
 {
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct extent_map *next;
 	bool ret = false;
 
@@ -1263,7 +1265,7 @@ static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
 	 * If the next extent is at its max capacity, defragging current extent
 	 * makes no sense, as the total number of extents won't change.
 	 */
-	if (next->len >= get_extent_max_capacity(em))
+	if (next->len >= get_extent_max_capacity(fs_info, em))
 		goto out;
 	/* Skip older extent */
 	if (next->generation < newer_than)
@@ -1400,6 +1402,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 				  bool locked, struct list_head *target_list,
 				  u64 *last_scanned_ret)
 {
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	bool last_is_target = false;
 	u64 cur = start;
 	int ret = 0;
@@ -1484,7 +1487,7 @@ static int defrag_collect_targets(struct btrfs_inode *inode,
 		 * Skip extents already at its max capacity, this is mostly for
 		 * compressed extents, which max cap is only 128K.
 		 */
-		if (em->len >= get_extent_max_capacity(em))
+		if (em->len >= get_extent_max_capacity(fs_info, em))
 			goto next;
 
 		/*