On Thu, Nov 11, 2021 at 12:48 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> On Wed, 2021-11-10 at 23:30 +0530, khiremat@xxxxxxxxxx wrote:
> > From: Kotresh HR <khiremat@xxxxxxxxxx>
> >
> > Problem:
> > The statfs reports incorrect free/available space
> > for quota less then CEPH_BLOCK size (4M).
> >
> > Solution:
> > For quota less than CEPH_BLOCK size, smaller block
> > size of 4K is used. But if quota is less than 4K,
> > it is decided to go with binary use/free of 4K
> > block. For quota size less than 4K size, report the
> > total=used=4K,free=0 when quota is full and
> > total=free=4K,used=0 otherwise.
> >
> > Signed-off-by: Kotresh HR <khiremat@xxxxxxxxxx>
> > ---
> > fs/ceph/quota.c | 14 ++++++++++++++
> > fs/ceph/super.h | 1 +
> > 2 files changed, 15 insertions(+)
> >
> > diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
> > index 620c691af40e..24ae13ea2241 100644
> > --- a/fs/ceph/quota.c
> > +++ b/fs/ceph/quota.c
> > @@ -494,10 +494,24 @@ bool ceph_quota_update_statfs(struct ceph_fs_client *fsc, struct kstatfs *buf)
> > if (ci->i_max_bytes) {
> > total = ci->i_max_bytes >> CEPH_BLOCK_SHIFT;
> > used = ci->i_rbytes >> CEPH_BLOCK_SHIFT;
> > + /* For quota size less than 4MB, use 4KB block size */
> > + if (!total) {
> > + total = ci->i_max_bytes >> CEPH_4K_BLOCK_SHIFT;
> > + used = ci->i_rbytes >> CEPH_4K_BLOCK_SHIFT;
> > + buf->f_frsize = 1 << CEPH_4K_BLOCK_SHIFT;
> > + }
> > /* It is possible for a quota to be exceeded.
> > * Report 'zero' in that case
> > */
> > free = total > used ? total - used : 0;
> > + /* For quota size less than 4KB, report the
> > + * total=used=4KB,free=0 when quota is full
> > + * and total=free=4KB, used=0 otherwise */
> > + if (!total) {
> > + total = 1;
> > + free = ci->i_max_bytes > ci->i_rbytes ? 1 : 0;
> > + buf->f_frsize = 1 << CEPH_4K_BLOCK_SHIFT;
> > + }
>
> We really ought to have the MDS establish a floor for the quota size.
> <4k quota seems ridiculous.
Yes, I have opened a tracker for the same.
https://tracker.ceph.com/issues/53228
>
>
> > }
> > spin_unlock(&ci->i_ceph_lock);
> > if (total) {
> > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > index ed51e04739c4..387ee33894db 100644
> > --- a/fs/ceph/super.h
> > +++ b/fs/ceph/super.h
> > @@ -32,6 +32,7 @@
> > * large volume sizes on 32-bit machines. */
> > #define CEPH_BLOCK_SHIFT 22 /* 4 MB */
> > #define CEPH_BLOCK (1 << CEPH_BLOCK_SHIFT)
> > +#define CEPH_4K_BLOCK_SHIFT 12 /* 4 KB */
> >
> > #define CEPH_MOUNT_OPT_CLEANRECOVER (1<<1) /* auto reonnect (clean mode) after blocklisted */
> > #define CEPH_MOUNT_OPT_DIRSTAT (1<<4) /* `cat dirname` for stats */
>
> This looks good, Kotresh. Nice work. I'll plan to merge this into
> testing in the near term.
>
> Before we merge this into mainline though, it would be good to have a
> testcase that ensures that this works like we expect with these small
> quotas.
>
> Could you write something for teuthology?
Sure, I will add a teuthology test for this.
>
>
> Thanks,
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
>
--
Thanks,
Kotresh HR
