From: Darrick J. Wong Date: Mon, 15 Apr 2024 23:07:33 +0000 (-0700) Subject: xfs: fix 32-bit truncation in xfs_compute_rextslog X-Git-Tag: v6.8.0~93 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a8ef1c96a30925e71cfdd46fe4701e84b463b1f5;p=thirdparty%2Fxfsprogs-dev.git xfs: fix 32-bit truncation in xfs_compute_rextslog Source kernel commit: cf8f0e6c1429be7652869059ea44696b72d5b726 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: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Bill O'Donnell --- diff --git a/libxfs/xfs_rtbitmap.c b/libxfs/xfs_rtbitmap.c index 90fe9028..726543ab 100644 --- a/libxfs/xfs_rtbitmap.c +++ b/libxfs/xfs_rtbitmap.c @@ -1130,14 +1130,16 @@ 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); } /*