ext4: remove unreachable code after ext4_can_extents_be_merged()

Commit ec22ba8e ("ext4: disable merging of uninitialized extents")
ensured that if either extent under consideration is uninit, we
decline to merge, and ext4_can_extents_be_merged() returns false.

So there is no need for the caller to then test whether the
extent under consideration is unitialized; if it were, we
wouldn't have gotten that far.

The comments were also inaccurate; ext4_can_extents_be_merged()
no longer XORs the states, it fails if *either* is uninit.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>

fs/ext4/extents.c

@@ -1715,7 +1715,6 @@ static int ext4_ext_try_to_merge_right(struct inode *inode,
 	struct ext4_extent_header *eh;
 	unsigned int depth, len;
 	int merge_done = 0;
-	int uninitialized = 0;
 
 	depth = ext_depth(inode);
 	BUG_ON(path[depth].p_hdr == NULL);
@@ -1725,12 +1724,8 @@ static int ext4_ext_try_to_merge_right(struct inode *inode,
 		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
 			break;
 		/* merge with next extent! */
-		if (ext4_ext_is_uninitialized(ex))
-			uninitialized = 1;
 		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
 				+ ext4_ext_get_actual_len(ex + 1));
-		if (uninitialized)
-			ext4_ext_mark_uninitialized(ex);
 
 		if (ex + 1 < EXT_LAST_EXTENT(eh)) {
 			len = (EXT_LAST_EXTENT(eh) - ex - 1)
@@ -1885,7 +1880,6 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
 	struct ext4_ext_path *npath = NULL;
 	int depth, len, err;
 	ext4_lblk_t next;
-	unsigned uninitialized = 0;
 	int mb_flags = 0;
 
 	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
@@ -1937,18 +1931,8 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
 			if (err)
 				return err;
 
-			/*
-			 * ext4_can_extents_be_merged should have checked
-			 * that either both extents are uninitialized, or
-			 * both aren't. Thus we need to check only one of
-			 * them here.
-			 */
-			if (ext4_ext_is_uninitialized(ex))
-				uninitialized = 1;
 			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
 					+ ext4_ext_get_actual_len(newext));
-			if (uninitialized)
-				ext4_ext_mark_uninitialized(ex);
 			eh = path[depth].p_hdr;
 			nearex = ex;
 			goto merge;
@@ -1971,20 +1955,10 @@ prepend:
 			if (err)
 				return err;
 
-			/*
-			 * ext4_can_extents_be_merged should have checked
-			 * that either both extents are uninitialized, or
-			 * both aren't. Thus we need to check only one of
-			 * them here.
-			 */
-			if (ext4_ext_is_uninitialized(ex))
-				uninitialized = 1;
 			ex->ee_block = newext->ee_block;
 			ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
 			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
 					+ ext4_ext_get_actual_len(newext));
-			if (uninitialized)
-				ext4_ext_mark_uninitialized(ex);
 			eh = path[depth].p_hdr;
 			nearex = ex;
 			goto merge;