Merge: Fix over reporting of free space or inodes in statvfs

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/851

JIRA: https://issues.redhat.com/browse/RHEL-87016

This requires the backport of a couple dependencies.

Omitted-fix: f87d3af (ext4 counterpart, not relevant to xfs)

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>

Approved-by: Bill O'Donnell <bodonnel@redhat.com>
Approved-by: Brian Foster <bfoster@redhat.com>
Approved-by: Andrey Albershteyn <aalbersh@redhat.com>

Merged-by: Julio Faracco <jfaracco@redhat.com>

Author: jcfaracco

fs/xfs/xfs_qm_bhv.c

@@ -19,28 +19,41 @@
 STATIC void
 xfs_fill_statvfs_from_dquot(
 	struct kstatfs		*statp,
+	struct xfs_inode	*ip,
 	struct xfs_dquot	*dqp)
 {
+	struct xfs_dquot_res	*blkres = &dqp->q_blk;
 	uint64_t		limit;
 
-	limit = dqp->q_blk.softlimit ?
-		dqp->q_blk.softlimit :
-		dqp->q_blk.hardlimit;
-	if (limit && statp->f_blocks > limit) {
-		statp->f_blocks = limit;
-		statp->f_bfree = statp->f_bavail =
-			(statp->f_blocks > dqp->q_blk.reserved) ?
-			 (statp->f_blocks - dqp->q_blk.reserved) : 0;
+	if (XFS_IS_REALTIME_MOUNT(ip->i_mount) &&
+	    (ip->i_diflags & (XFS_DIFLAG_RTINHERIT | XFS_DIFLAG_REALTIME)))
+		blkres = &dqp->q_rtb;
+
+	limit = blkres->softlimit ?
+		blkres->softlimit :
+		blkres->hardlimit;
+	if (limit) {
+		uint64_t	remaining = 0;
+
+		if (limit > blkres->reserved)
+			remaining = limit - blkres->reserved;
+
+		statp->f_blocks = min(statp->f_blocks, limit);
+		statp->f_bfree = min(statp->f_bfree, remaining);
+		statp->f_bavail = min(statp->f_bavail, remaining);
 	}
 
 	limit = dqp->q_ino.softlimit ?
 		dqp->q_ino.softlimit :
 		dqp->q_ino.hardlimit;
-	if (limit && statp->f_files > limit) {
-		statp->f_files = limit;
-		statp->f_ffree =
-			(statp->f_files > dqp->q_ino.reserved) ?
-			 (statp->f_files - dqp->q_ino.reserved) : 0;
+	if (limit) {
+		uint64_t	remaining = 0;
+
+		if (limit > dqp->q_ino.reserved)
+			remaining = limit - dqp->q_ino.reserved;
+
+		statp->f_files = min(statp->f_files, limit);
+		statp->f_ffree = min(statp->f_ffree, remaining);
 	}
 }
 
@@ -61,7 +74,7 @@ xfs_qm_statvfs(
 	struct xfs_dquot	*dqp;
 
 	if (!xfs_qm_dqget(mp, ip->i_projid, XFS_DQTYPE_PROJ, false, &dqp)) {
-		xfs_fill_statvfs_from_dquot(statp, dqp);
+		xfs_fill_statvfs_from_dquot(statp, ip, dqp);
 		xfs_qm_dqput(dqp);
 	}
 }

fs/xfs/xfs_super.c

@@ -873,12 +873,6 @@ xfs_fs_statfs(
 	ffree = statp->f_files - (icount - ifree);
 	statp->f_ffree = max_t(int64_t, ffree, 0);
 
-
-	if ((ip->i_diflags & XFS_DIFLAG_PROJINHERIT) &&
-	    ((mp->m_qflags & (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))) ==
-			      (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))
-		xfs_qm_statvfs(ip, statp);
-
 	if (XFS_IS_REALTIME_MOUNT(mp) &&
 	    (ip->i_diflags & (XFS_DIFLAG_RTINHERIT | XFS_DIFLAG_REALTIME))) {
 		s64	freertx;
@@ -888,6 +882,11 @@ xfs_fs_statfs(
 		statp->f_bavail = statp->f_bfree = xfs_rtx_to_rtb(mp, freertx);
 	}
 
+	if ((ip->i_diflags & XFS_DIFLAG_PROJINHERIT) &&
+	    ((mp->m_qflags & (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))) ==
+			      (XFS_PQUOTA_ACCT|XFS_PQUOTA_ENFD))
+		xfs_qm_statvfs(ip, statp);
+
 	return 0;
 }