btrfs: replace error code from btrfs_drop_extents

There's a case which clone does not handle and used to BUG_ON instead,
(testcase xfstests/btrfs/035), now returns EINVAL. This error code is
confusing to the ioctl caller, as it normally signifies errorneous
arguments.

Change it to ENOPNOTSUPP which allows a fall back to copy instead of
clone. This does not affect the common reflink operation.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/file.c

@@ -805,7 +805,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
 		if (start > key.offset && end < extent_end) {
 			BUG_ON(del_nr > 0);
 			if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
-				ret = -EINVAL;
+				ret = -EOPNOTSUPP;
 				break;
 			}
 
@@ -851,7 +851,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
 		 */
 		if (start <= key.offset && end < extent_end) {
 			if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
-				ret = -EINVAL;
+				ret = -EOPNOTSUPP;
 				break;
 			}
 
@@ -877,7 +877,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
 		if (start > key.offset && end >= extent_end) {
 			BUG_ON(del_nr > 0);
 			if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
-				ret = -EINVAL;
+				ret = -EOPNOTSUPP;
 				break;
 			}
 

fs/btrfs/ioctl.c

@@ -3088,7 +3088,7 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
 							 new_key.offset + datal,
 							 1);
 				if (ret) {
-					if (ret != -EINVAL)
+					if (ret != -EOPNOTSUPP)
 						btrfs_abort_transaction(trans,
 								root, ret);
 					btrfs_end_transaction(trans, root);
@@ -3163,7 +3163,7 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
 							 new_key.offset + datal,
 							 1);
 				if (ret) {
-					if (ret != -EINVAL)
+					if (ret != -EOPNOTSUPP)
 						btrfs_abort_transaction(trans,
 							root, ret);
 					btrfs_end_transaction(trans, root);