--- fs/ext4/inode.c

+++ fs/ext4/inode.c

@@ -5458,13 +5458,12 @@ static int ext4_indirect_trans_blocks(st

/* if nrblocks are contiguous */

if (chunk) {

/*

- * With N contiguous data blocks, it need at most

- * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks

- * 2 dindirect blocks

- * 1 tindirect block

+ * With N contiguous data blocks, we need at most

+ * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,

+ * 2 dindirect blocks, and 1 tindirect block

*/

- indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);

- return indirects + 3;

+ return DIV_ROUND_UP(nrblocks,

+ EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;

}

/*

* if nrblocks are not contiguous, worse case, each block touch