Merge: ext4: don't over-report free space or inodes in statvfs

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7601

Backport upstream fix for RHEL-125357 on CentOS 9.8.

JIRA: https://issues.redhat.com/browse/RHEL-125357

Signed-off-by: Ravi Singh <ravising@redhat.com>

Approved-by: Pavel Reichl <preichl@redhat.com>
Approved-by: Carlos Maiolino <cmaiolino@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

Author: CKI KWF Bot

fs/ext4/super.c

@@ -6808,22 +6808,29 @@ static int ext4_statfs_project(struct super_block *sb,
 			     dquot->dq_dqb.dqb_bhardlimit);
 	limit >>= sb->s_blocksize_bits;
 
-	if (limit && buf->f_blocks > limit) {
+	if (limit) {
+		uint64_t	remaining = 0;
+
 		curblock = (dquot->dq_dqb.dqb_curspace +
 			    dquot->dq_dqb.dqb_rsvspace) >> sb->s_blocksize_bits;
-		buf->f_blocks = limit;
-		buf->f_bfree = buf->f_bavail =
-			(buf->f_blocks > curblock) ?
-			 (buf->f_blocks - curblock) : 0;
+		if (limit > curblock)
+			remaining = limit - curblock;
+
+		buf->f_blocks = min(buf->f_blocks, limit);
+		buf->f_bfree = min(buf->f_bfree, remaining);
+		buf->f_bavail = min(buf->f_bavail, remaining);
 	}
 
 	limit = min_not_zero(dquot->dq_dqb.dqb_isoftlimit,
 			     dquot->dq_dqb.dqb_ihardlimit);
-	if (limit && buf->f_files > limit) {
-		buf->f_files = limit;
-		buf->f_ffree =
-			(buf->f_files > dquot->dq_dqb.dqb_curinodes) ?
-			 (buf->f_files - dquot->dq_dqb.dqb_curinodes) : 0;
+	if (limit) {
+		uint64_t	remaining = 0;
+
+		if (limit > dquot->dq_dqb.dqb_curinodes)
+			remaining = limit - dquot->dq_dqb.dqb_curinodes;
+
+		buf->f_files = min(buf->f_files, limit);
+		buf->f_ffree = min(buf->f_ffree, remaining);
 	}
 
 	spin_unlock(&dquot->dq_dqb_lock);