Commit cf8f0e6c authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: fix 32-bit truncation in xfs_compute_rextslog 



It's quite reasonable that some customer somewhere will want to
configure a realtime volume with more than 2^32 extents.  If they try to
do this, the highbit32() call will truncate the upper bits of the
xfs_rtbxlen_t and produce the wrong value for rextslog.  This in turn
causes the rsumlevels to be wrong, which results in a realtime summary
file that is the wrong length.  Fix that.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent a6a38f30

fs/xfs/libxfs/xfs_rtbitmap.c

+5 −3
Original line number Diff line number Diff line
@@ -1132,14 +1132,16 @@ xfs_rtbitmap_blockcount( 


/*

 * Compute the maximum level number of the realtime summary file, as defined by

 * mkfs.  The use of highbit32 on a 64-bit quantity is a historic artifact that

 * prohibits correct use of rt volumes with more than 2^32 extents.

 * mkfs.  The historic use of highbit32 on a 64-bit quantity prohibited correct

 * use of rt volumes with more than 2^32 extents.

 */

uint8_t

xfs_compute_rextslog(

	xfs_rtbxlen_t		rtextents)

{

	return rtextents ? xfs_highbit32(rtextents) : 0;

	if (!rtextents)

		return 0;

	return xfs_highbit64(rtextents);

}



/*