btrfs: handle errors returned from unpin_extent_cache()

We've had numerous attempts to let function unpin_extent_cache() return
void as it only returns 0. There are still error cases to handle so do
that, in addition to the verbose messages. The only caller
btrfs_finish_one_ordered() will now abort the transaction, previously it
let it continue which could lead to further problems.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_map.c

@@ -290,6 +290,10 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
  * Called after an extent has been written to disk properly.  Set the generation
  * to the generation that actually added the file item to the inode so we know
  * we need to sync this extent when we call fsync().
+ *
+ * Returns: 0	     on success
+ * 	    -ENOENT  when the extent is not found in the tree
+ * 	    -EUCLEAN if the found extent does not match the expected start
  */
 int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen)
 {
@@ -307,14 +311,18 @@ int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen)
 "no extent map found for inode %llu (root %lld) when unpinning extent range [%llu, %llu), generation %llu",
 			   btrfs_ino(inode), btrfs_root_id(inode->root),
 			   start, len, gen);
+		ret = -ENOENT;
 		goto out;
 	}
 
-	if (WARN_ON(em->start != start))
+	if (WARN_ON(em->start != start)) {
 		btrfs_warn(fs_info,
 "found extent map for inode %llu (root %lld) with unexpected start offset %llu when unpinning extent range [%llu, %llu), generation %llu",
 			   btrfs_ino(inode), btrfs_root_id(inode->root),
 			   em->start, start, len, gen);
+		ret = -EUCLEAN;
+		goto out;
+	}
 
 	em->generation = gen;
 	em->flags &= ~EXTENT_FLAG_PINNED;

fs/btrfs/inode.c

@@ -3125,7 +3125,12 @@ int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
 						ordered_extent->disk_num_bytes);
 		}
 	}
-	unpin_extent_cache(inode, ordered_extent->file_offset,
+	if (ret < 0) {
+		btrfs_abort_transaction(trans, ret);
+		goto out;
+	}
+
+	ret = unpin_extent_cache(inode, ordered_extent->file_offset,
 				 ordered_extent->num_bytes, trans->transid);
 	if (ret < 0) {
 		btrfs_abort_transaction(trans, ret);