From eedf32bfcace7d8e20cc66757d74fc68f3439ff7 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Mon, 4 Aug 2014 11:35:35 +1000 Subject: xfs: fix rounding error of fiemap length parameter The offset and length parameters are converted from bytes to basic blocks by xfs_vn_fiemap(). The BTOBB() converter rounds the value up to the nearest basic block. This leads to unexpected behavior when unaligned offsets are provided to FIEMAP. Fix the conversions of byte values to block values to cover the provided offsets. Round down the start offset to the nearest basic block. Calculate the end offset based on the provided values, round up and calculate length based on the start block offset. Reported-by: Chandan Rajendra Signed-off-by: Brian Foster Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/xfs/xfs_iops.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index d75621ae3e36..72129493e9d3 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -1055,12 +1055,12 @@ xfs_vn_fiemap( return error; /* Set up bmap header for xfs internal routine */ - bm.bmv_offset = BTOBB(start); + bm.bmv_offset = BTOBBT(start); /* Special case for whole file */ if (length == FIEMAP_MAX_OFFSET) bm.bmv_length = -1LL; else - bm.bmv_length = BTOBB(length); + bm.bmv_length = BTOBB(start + length) - bm.bmv_offset; /* We add one because in getbmap world count includes the header */ bm.bmv_count = !fieinfo->fi_extents_max ? MAXEXTNUM : -- cgit v1.2.3-59-g8ed1b