btrfs: add helper to replace extent map range with a new extent map

We have several places that need to drop all the extent maps in a given
file range and then add a new extent map for that range. Currently they
call btrfs_drop_extent_map_range() to delete all extent maps in the range
and then keep trying to add the new extent map in a loop that keeps
retrying while the insertion of the new extent map fails with -EEXIST.

So instead of repeating this logic, add a helper to extent_map.c that
does these steps and name it btrfs_replace_extent_map_range(). Also add
a comment about why the retry loop is necessary.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 1 insertions, 7 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index d8a8c849584d..176b432035ae 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2359,7 +2359,6 @@ static int fill_holes(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	struct btrfs_file_extent_item *fi;
 	struct extent_map *hole_em;
-	struct extent_map_tree *em_tree = &inode->extent_tree;
 	struct btrfs_key key;
 	int ret;
 
@@ -2440,12 +2439,7 @@ out:
 		hole_em->compress_type = BTRFS_COMPRESS_NONE;
 		hole_em->generation = trans->transid;
 
-		do {
-			btrfs_drop_extent_map_range(inode, offset, end - 1, false);
-			write_lock(&em_tree->lock);
-			ret = add_extent_mapping(em_tree, hole_em, 1);
-			write_unlock(&em_tree->lock);
-		} while (ret == -EEXIST);
+		ret = btrfs_replace_extent_map_range(inode, hole_em, true);
 		free_extent_map(hole_em);
 		if (ret)
 			btrfs_set_inode_full_sync(inode);