[PATCH v1 1/1] ceph: Fix incorrect statfs report for small quota

[khiremat@redhat.com]

From: Kotresh HR <khiremat@redhat.com>

Problem:
The statfs reports incorrect free/available space
for quota less then CEPH_BLOCK size (4M).

Solution:
For quotas less than CEPH_BLOCK size, it is
decided to go with binary use/free of full block.
For quota size less than CEPH_BLOCK size, report
the total=used=CEPH_BLOCK,free=0 when quota is
full and total=free=CEPH_BLOCK, used=0 otherwise.

Signed-off-by: Kotresh HR <khiremat@redhat.com>
---
 fs/ceph/quota.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
index 620c691af40e..d49ba82d08bf 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -505,6 +505,22 @@ bool ceph_quota_update_statfs(struct ceph_fs_client *fsc, struct kstatfs *buf)
 			buf->f_bfree = free;
 			buf->f_bavail = free;
 			is_updated = true;
+		} else if (ci->i_max_bytes) {
+			/* For quota size less than CEPH_BLOCK size, report
+			 * the total=used=CEPH_BLOCK,free=0 when quota is full and
+			 * total=free=CEPH_BLOCK, used=0 otherwise  */
+			total = ci->i_max_bytes;
+			used = ci->i_rbytes;
+
+			buf->f_blocks = 1;
+			if (total > used) {
+				buf->f_bfree = 1;
+				buf->f_bavail = 1;
+			} else {
+				buf->f_bfree = 0;
+				buf->f_bavail = 0;
+			}
+			is_updated = true;
 		}
 		iput(in);
 	}
-- 
2.31.1