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

This fixes an analogus bug that was fixed in xfs in commit
4b8d867ca6e2 ("xfs: don't over-report free space or inodes in
statvfs") where statfs can report misleading / incorrect information
where project quota is enabled, and the free space is less than the
remaining quota.

This commit will resolve a test failure in generic/762 which tests for
this bug.

Cc: stable@kernel.org
Fixes: 689c958cbe6b ("ext4: add project quota support")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4768770715cae56b060869659444f63e88be410f..8cafcd3e9f5fe1a6f8092a1ae44e0e2a13526525 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6820,22 +6820,29 @@ 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);