xfs: Add a comment in xfs_log_sb()

Source kernel commit: ac1d977096a17d56c55bd7f90be48e81ac4cec3f

Add a comment explaining why the sb_frextents are updated outside the
if (xfs_has_lazycount(mp) check even though it is a lazycounter.
RT groups are supported only in v5 filesystems which always have
lazycounter enabled - so putting it inside the if(xfs_has_lazycount(mp)
check is redundant.

Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c
index b29077dcd0aed737e935dc72ea2b200c298df880..7a1d85b86e59eabf456c50d15265dc8faf427e1e 100644 (file)
--- a/libxfs/xfs_sb.c
+++ b/libxfs/xfs_sb.c
@@ -1345,6 +1345,9 @@ xfs_log_sb(
         * feature was introduced.  This counter can go negative due to the way
         * we handle nearly-lockless reservations, so we must use the _positive
         * variant here to avoid writing out nonsense frextents.
+        *
+        * RT groups are only supported on v5 file systems, which always
+        * have lazy SB counters.
         */
        if (xfs_has_rtgroups(mp) && !xfs_has_zoned(mp)) {
                mp->m_sb.sb_frextents =