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xfs: fix 32-bit truncation in xfs_compute_rextslog

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commit cf8f0e6c1429be7652869059ea44696b72d5b726 upstream.

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 <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Darrick J. Wong 2024-03-26 17:12:18 -07:00 committed by Greg Kroah-Hartman
parent 0a31f1e8d8
commit 89e511a745
1 changed files with 5 additions and 3 deletions
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8
fs/xfs/libxfs/xfs_rtbitmap.c
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@ -1133,13 +1133,15 @@ xfs_rtalloc_extent_is_free(
/*
* 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);
}