Linux-libre 4.8.2-gnupck-4.8.2-gnu

1 files changed, 21 insertions, 0 deletions

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 9f9992b37..4c40c0786 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1194,6 +1194,27 @@ static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
 }
 
 /*
+ * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
+ * with filesystem metadata blocksi.
+ */
+int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
+			  unsigned int count)
+{
+	if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
+	    (start_blk + count < start_blk) ||
+	    (start_blk > le32_to_cpu(sbi->s_es->s_blocks_count)))
+		return 0;
+
+	/* Ensure we do not step over superblock */
+	if ((start_blk <= sbi->s_sb_block) &&
+	    (start_blk + count >= sbi->s_sb_block))
+		return 0;
+
+
+	return 1;
+}
+
+/*
  * ext2_new_blocks() -- core block(s) allocation function
  * @inode:		file inode
  * @goal:		given target block(filesystem wide)