ext4: get rid of ppath in ext4_ext_convert_to_initialized()

The use of path and ppath is now very confusing, so to make the code more
readable, pass path between functions uniformly, and get rid of ppath.

To get rid of the ppath in ext4_ext_convert_to_initialized(), the following
is done here:

 * Free the extents path when an error is encountered.
 * Its caller needs to update ppath if it uses ppath.
 * The 'allocated' is changed from passing a value to passing an address.

No functional changes.

Signed-off-by: Baokun Li <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Ojaswin Mujoo <[email protected]>
Tested-by: Ojaswin Mujoo <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: LiBaokun96

fs/ext4/extents.c

@@ -3438,13 +3438,11 @@ static struct ext4_ext_path *ext4_split_extent(handle_t *handle,
  *    that are allocated and initialized.
  *    It is guaranteed to be >= map->m_len.
  */
-static int ext4_ext_convert_to_initialized(handle_t *handle,
-					   struct inode *inode,
-					   struct ext4_map_blocks *map,
-					   struct ext4_ext_path **ppath,
-					   int flags)
+static struct ext4_ext_path *
+ext4_ext_convert_to_initialized(handle_t *handle, struct inode *inode,
+			struct ext4_map_blocks *map, struct ext4_ext_path *path,
+			int flags, unsigned int *allocated)
 {
-	struct ext4_ext_path *path = *ppath;
 	struct ext4_sb_info *sbi;
 	struct ext4_extent_header *eh;
 	struct ext4_map_blocks split_map;
@@ -3454,7 +3452,6 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 	unsigned int ee_len, depth, map_len = map->m_len;
 	int err = 0;
 	int split_flag = EXT4_EXT_DATA_VALID2;
-	int allocated = 0;
 	unsigned int max_zeroout = 0;
 
 	ext_debug(inode, "logical block %llu, max_blocks %u\n",
@@ -3495,6 +3492,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 	 *  - L2: we only attempt to merge with an extent stored in the
 	 *    same extent tree node.
 	 */
+	*allocated = 0;
 	if ((map->m_lblk == ee_block) &&
 		/* See if we can merge left */
 		(map_len < ee_len) &&		/*L1*/
@@ -3524,7 +3522,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 			(prev_len < (EXT_INIT_MAX_LEN - map_len))) {	/*C4*/
 			err = ext4_ext_get_access(handle, inode, path + depth);
 			if (err)
-				goto out;
+				goto errout;
 
 			trace_ext4_ext_convert_to_initialized_fastpath(inode,
 				map, ex, abut_ex);
@@ -3539,7 +3537,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 			abut_ex->ee_len = cpu_to_le16(prev_len + map_len);
 
 			/* Result: number of initialized blocks past m_lblk */
-			allocated = map_len;
+			*allocated = map_len;
 		}
 	} else if (((map->m_lblk + map_len) == (ee_block + ee_len)) &&
 		   (map_len < ee_len) &&	/*L1*/
@@ -3570,7 +3568,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 		    (next_len < (EXT_INIT_MAX_LEN - map_len))) {	/*C4*/
 			err = ext4_ext_get_access(handle, inode, path + depth);
 			if (err)
-				goto out;
+				goto errout;
 
 			trace_ext4_ext_convert_to_initialized_fastpath(inode,
 				map, ex, abut_ex);
@@ -3585,18 +3583,20 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 			abut_ex->ee_len = cpu_to_le16(next_len + map_len);
 
 			/* Result: number of initialized blocks past m_lblk */
-			allocated = map_len;
+			*allocated = map_len;
 		}
 	}
-	if (allocated) {
+	if (*allocated) {
 		/* Mark the block containing both extents as dirty */
 		err = ext4_ext_dirty(handle, inode, path + depth);
 
 		/* Update path to point to the right extent */
 		path[depth].p_ext = abut_ex;
+		if (err)
+			goto errout;
 		goto out;
 	} else
-		allocated = ee_len - (map->m_lblk - ee_block);
+		*allocated = ee_len - (map->m_lblk - ee_block);
 
 	WARN_ON(map->m_lblk < ee_block);
 	/*
@@ -3623,21 +3623,21 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 	split_map.m_lblk = map->m_lblk;
 	split_map.m_len = map->m_len;
 
-	if (max_zeroout && (allocated > split_map.m_len)) {
-		if (allocated <= max_zeroout) {
+	if (max_zeroout && (*allocated > split_map.m_len)) {
+		if (*allocated <= max_zeroout) {
 			/* case 3 or 5 */
 			zero_ex1.ee_block =
 				 cpu_to_le32(split_map.m_lblk +
 					     split_map.m_len);
 			zero_ex1.ee_len =
-				cpu_to_le16(allocated - split_map.m_len);
+				cpu_to_le16(*allocated - split_map.m_len);
 			ext4_ext_store_pblock(&zero_ex1,
 				ext4_ext_pblock(ex) + split_map.m_lblk +
 				split_map.m_len - ee_block);
 			err = ext4_ext_zeroout(inode, &zero_ex1);
 			if (err)
 				goto fallback;
-			split_map.m_len = allocated;
+			split_map.m_len = *allocated;
 		}
 		if (split_map.m_lblk - ee_block + split_map.m_len <
 								max_zeroout) {
@@ -3655,27 +3655,24 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 
 			split_map.m_len += split_map.m_lblk - ee_block;
 			split_map.m_lblk = ee_block;
-			allocated = map->m_len;
+			*allocated = map->m_len;
 		}
 	}
 
 fallback:
 	path = ext4_split_extent(handle, inode, path, &split_map, split_flag,
 				 flags, NULL);
-	if (IS_ERR(path)) {
-		err = PTR_ERR(path);
-		*ppath = NULL;
-		goto out;
-	}
-	err = 0;
-	*ppath = path;
+	if (IS_ERR(path))
+		return path;
 out:
 	/* If we have gotten a failure, don't zero out status tree */
-	if (!err) {
-		ext4_zeroout_es(inode, &zero_ex1);
-		ext4_zeroout_es(inode, &zero_ex2);
-	}
-	return err ? err : allocated;
+	ext4_zeroout_es(inode, &zero_ex1);
+	ext4_zeroout_es(inode, &zero_ex2);
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
 }
 
 /*
@@ -3897,7 +3894,6 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 			struct ext4_ext_path **ppath, int flags,
 			unsigned int allocated, ext4_fsblk_t newblock)
 {
-	int ret = 0;
 	int err = 0;
 
 	ext_debug(inode, "logical block %llu, max_blocks %u, flags 0x%x, allocated %u\n",
@@ -3977,23 +3973,24 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 	 * For buffered writes, at writepage time, etc.  Convert a
 	 * discovered unwritten extent to written.
 	 */
-	ret = ext4_ext_convert_to_initialized(handle, inode, map, ppath, flags);
-	if (ret < 0) {
-		err = ret;
+	*ppath = ext4_ext_convert_to_initialized(handle, inode, map, *ppath,
+						 flags, &allocated);
+	if (IS_ERR(*ppath)) {
+		err = PTR_ERR(*ppath);
+		*ppath = NULL;
 		goto out2;
 	}
 	ext4_update_inode_fsync_trans(handle, inode, 1);
 	/*
-	 * shouldn't get a 0 return when converting an unwritten extent
+	 * shouldn't get a 0 allocated when converting an unwritten extent
 	 * unless m_len is 0 (bug) or extent has been corrupted
 	 */
-	if (unlikely(ret == 0)) {
-		EXT4_ERROR_INODE(inode, "unexpected ret == 0, m_len = %u",
+	if (unlikely(allocated == 0)) {
+		EXT4_ERROR_INODE(inode, "unexpected allocated == 0, m_len = %u",
 				 map->m_len);
 		err = -EFSCORRUPTED;
 		goto out2;
 	}
-	allocated = ret;
 
 out:
 	map->m_flags |= EXT4_MAP_NEW;