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.
> }
> 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?
Thanks,
--
Jeff Layton <jlayton@xxxxxxxxxx>
