X-Git-Url: https://git.carlh.net/gitweb/?a=blobdiff_plain;f=src%2Fext4_extent.c;h=28db8533b4d14ce5331985143af71f4cd449dde4;hb=13875d2d90245070874fb7e85d9dcd86699bca5e;hp=f5148a7a66dad82636286cb68ccac7cb7a6bf5e3;hpb=6c6fb14455806704ea7814a31747ec551cb39928;p=lwext4.git

diff --git a/src/ext4_extent.c b/src/ext4_extent.c
index f5148a7..28db853 100644
--- a/src/ext4_extent.c
+++ b/src/ext4_extent.c
@@ -529,14 +529,14 @@ static int ext4_find_extent(struct ext4_inode_ref *inode_ref, ext4_lblk_t block,
 	if (path) {
 		ext4_ext_drop_refs(inode_ref, path, 0);
 		if (depth > path[0].maxdepth) {
-			free(path);
+			ext4_free(path);
 			*orig_path = path = NULL;
 		}
 	}
 	if (!path) {
 		int32_t path_depth = depth + 1;
 		/* account possible depth increase */
-		path = calloc(1, sizeof(struct ext4_extent_path) *
+		path = ext4_calloc(1, sizeof(struct ext4_extent_path) *
 				     (path_depth + 1));
 		if (!path)
 			return ENOMEM;
@@ -592,7 +592,7 @@ static int ext4_find_extent(struct ext4_inode_ref *inode_ref, ext4_lblk_t block,
 
 err:
 	ext4_ext_drop_refs(inode_ref, path, 0);
-	free(path);
+	ext4_free(path);
 	if (orig_path)
 		*orig_path = NULL;
 	return ret;
@@ -1130,7 +1130,7 @@ again:
 		i = depth - (level - 1);
 		/* We split from leaf to the i-th node */
 		if (level > 0) {
-			npath = calloc(1, sizeof(struct ext4_extent_path) *
+			npath = ext4_calloc(1, sizeof(struct ext4_extent_path) *
 					      (level));
 			if (!npath) {
 				ret = ENOMEM;
@@ -1168,7 +1168,7 @@ out:
 		}
 	}
 	if (npath)
-		free(npath);
+		ext4_free(npath);
 
 	return ret;
 }
@@ -1215,6 +1215,13 @@ static int ext4_ext_remove_idx(struct ext4_inode_ref *inode_ref,
 		 to_le32(path[i].index->first_block), leaf, 1);
 	ext4_ext_free_blocks(inode_ref, leaf, 1, 0);
 
+	/*
+	 * We may need to correct the paths after the first extents/indexes in
+	 * a node being modified.
+	 *
+	 * We do not need to consider whether there's any extents presenting or
+	 * not, as garbage will be cleared soon.
+	 */
 	while (i > 0) {
 		if (path[i].index != EXT_FIRST_INDEX(path[i].header))
 			break;
@@ -1253,15 +1260,27 @@ static int ext4_ext_remove_leaf(struct ext4_inode_ref *inode_ref,
 		new_start = start = to_le32(ex->first_block);
 		len = ext4_ext_get_actual_len(ex);
 		newblock = ext4_ext_pblock(ex);
+		/*
+		 * The 1st case:
+		 *   The position that we start truncation is inside the range of an
+		 *   extent. Here we should calculate the new length of that extent and
+		 *   may start the removal from the next extent.
+		 */
 		if (start < from) {
 			len -= from - start;
 			new_len = from - start;
 			start = from;
 			start_ex++;
 		} else {
+			/*
+			 * The second case:
+			 *   The last block to be truncated is inside the range of an
+			 *   extent. We need to calculate the new length and the new
+			 *   start of the extent.
+			 */
 			if (start + len - 1 > to) {
-				len -= start + len - 1 - to;
 				new_len = start + len - 1 - to;
+				len -= new_len;
 				new_start = to + 1;
 				newblock += to + 1 - start;
 				ex2 = ex;
@@ -1269,7 +1288,15 @@ static int ext4_ext_remove_leaf(struct ext4_inode_ref *inode_ref,
 		}
 
 		ext4_ext_remove_blocks(inode_ref, ex, start, start + len - 1);
+		/*
+		 * Set the first block of the extent if it is presented.
+		 */
 		ex->first_block = to_le32(new_start);
+
+		/*
+		 * If the new length of the current extent we are working on is
+		 * zero, remove it.
+		 */
 		if (!new_len)
 			new_entries--;
 		else {
@@ -1286,12 +1313,21 @@ static int ext4_ext_remove_leaf(struct ext4_inode_ref *inode_ref,
 	if (ex2 == NULL)
 		ex2 = ex;
 
+	/*
+	 * Move any remaining extents to the starting position of the node.
+	 */
 	if (ex2 <= EXT_LAST_EXTENT(eh))
 		memmove(start_ex, ex2, (EXT_LAST_EXTENT(eh) - ex2 + 1) *
 					   sizeof(struct ext4_extent));
 
 	eh->entries_count = to_le16(new_entries);
 	ext4_ext_dirty(inode_ref, path + depth);
+
+	/*
+	 * If the extent pointer is pointed to the first extent of the node, and
+	 * there's still extents presenting, we may need to correct the indexes
+	 * of the paths.
+	 */
 	if (path[depth].extent == EXT_FIRST_EXTENT(eh) && eh->entries_count) {
 		err = ext4_ext_correct_indexes(inode_ref, path);
 		if (err != EOK)
@@ -1308,6 +1344,9 @@ static int ext4_ext_remove_leaf(struct ext4_inode_ref *inode_ref,
 	return err;
 }
 
+/*
+ * Check if there's more to remove at a specific level.
+ */
 static bool ext4_ext_more_to_rm(struct ext4_extent_path *path, ext4_lblk_t to)
 {
 	if (!to_le16(path->header->entries_count))
@@ -1427,6 +1466,9 @@ int ext4_extent_remove_space(struct ext4_inode_ref *inode_ref, ext4_lblk_t from,
 			i++;
 		} else {
 			if (i > 0) {
+				/*
+				 * Garbage entries will finally be cleared here.
+				 */
 				if (!eh->entries_count)
 					ret = ext4_ext_remove_idx(inode_ref,
 								  path, i - 1);
@@ -1456,7 +1498,7 @@ int ext4_extent_remove_space(struct ext4_inode_ref *inode_ref, ext4_lblk_t from,
 
 out:
 	ext4_ext_drop_refs(inode_ref, path, 0);
-	free(path);
+	ext4_free(path);
 	path = NULL;
 	return ret;
 }
@@ -1750,7 +1792,7 @@ out:
 out2:
 	if (path) {
 		ext4_ext_drop_refs(inode_ref, path, 0);
-		free(path);
+		ext4_free(path);
 	}
 
 	return err;