ext4: remove unreachable code in 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 <[email protected]>

---

Disclaimer: compile-tested only.

fs/ext4/extents.c +0 -27

index de6d467..35f65cf 100644
@@ -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;
 
 
--

To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

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 <[email protected]>

commit
ec22ba8e ext4: disable merging of uninitialized extents

ensured that if either extent under consideration is uninit, we decline to merge, and immediately return.

But right after that test, we test again for an uninit extent; we can never hit this. So just remove the impossible test and associated variable.

Signed-off-by Eric Sandeen <[email protected]>

---

Disclosure: compile-tested only.

fs/ext4/extents.c +2 -8

index 54d52af..de6d467 100644
@@ -1666,7 +1666,7 @@ int
 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
 				struct ext4_extent *ex2)
 {
-	unsigned short ext1_ee_len, ext2_ee_len, max_len;
+	unsigned short ext1_ee_len, ext2_ee_len;
 
 	/*
 	 * Make sure that both extents are initialized. We don't merge

@@ -1677,11 +1677,6 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
 	if (ext4_ext_is_uninitialized(ex1) || ext4_ext_is_uninitialized(ex2))
 		return 0;
 
-	if (ext4_ext_is_uninitialized(ex1))
-		max_len = EXT_UNINIT_MAX_LEN;
-	else
-		max_len = EXT_INIT_MAX_LEN;
-
 	ext1_ee_len = ext4_ext_get_actual_len(ex1);
 	ext2_ee_len = ext4_ext_get_actual_len(ex2);
 

@@ -1694,7 +1689,7 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
 	 * as an RO_COMPAT feature, refuse to merge to extents if
 	 * this can result in the top bit of ee_len being set.
 	 */
-	if (ext1_ee_len + ext2_ee_len > max_len)
+	if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
 		return 0;
 #ifdef AGGRESSIVE_TEST
 	if (ext1_ee_len >= 4)
 
--

To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

commit
ec22ba8e ext4: disable merging of uninitialized extents

ensured that if either extent under consideration is uninit, we decline to merge, and immediately return.

But right after that test, we test again for an uninit extent; we can never hit this. So just remove the impossible test and associated variable.

Signed-off-by Eric Sandeen <[email protected]>