xfs: move the xfs_is_always_cow_inode check into xfs_alloc_file_space

Move the xfs_is_always_cow_inode check from the caller into
xfs_alloc_file_space to prepare for refactoring of xfs_file_fallocate.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240827065123.1762168-6-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/xfs/xfs_bmap_util.c

@@ -653,6 +653,9 @@ xfs_alloc_file_space(
 	xfs_bmbt_irec_t		imaps[1], *imapp;
 	int			error;
 
+	if (xfs_is_always_cow_inode(ip))
+		return 0;
+
 	trace_xfs_alloc_file_space(ip);
 
 	if (xfs_is_shutdown(mp))

fs/xfs/xfs_file.c

@@ -987,11 +987,9 @@ xfs_file_fallocate(
 			}
 		}
 
-		if (!xfs_is_always_cow_inode(ip)) {
-			error = xfs_alloc_file_space(ip, offset, len);
-			if (error)
-				goto out_unlock;
-		}
+		error = xfs_alloc_file_space(ip, offset, len);
+		if (error)
+			goto out_unlock;
 	}
 
 	/* Change file size if needed */