ext4: trim allocation requests to group size

If filesystem groups are artifically small (using parameter -g to mkfs.ext4), ext4_mb_normalize_request() can result in a request that is larger than a block group. Trim the request size to not confuse allocation code. Reported-by: "Kirill A. Shutemov" <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]> Cc: [email protected]
pop-os · Jan 27, 2017 · cd648b8 · cd648b8
1 parent 43c7322
commit cd648b8
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
@@ -3133,6 +3133,13 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	if (ar->pright && start + size - 1 >= ar->lright)
 		size -= start + size - ar->lright;
 
+	/*
+	 * Trim allocation request for filesystems with artificially small
+	 * groups.
+	 */
+	if (size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb))
+		size = EXT4_BLOCKS_PER_GROUP(ac->ac_sb);
+
 	end = start + size;
 
 	/* check we don't cross already preallocated blocks */