Re: [PATCH] xfs: improve handling of prjquot ENOSPC

[Dave Chinner <david@fromorbit.com>]

On Thu, Dec 14, 2023 at 11:07:08PM +0800, Jian Wen wrote:
> Don't clear space of the whole fs when the project quota limit is
> reached, since it affects the writing performance of files of
> the directories that are under quota.
> 
> Only run cow/eofblocks scans on the quota attached to the inode.
> 
> Signed-off-by: Jian Wen <wenjian1@xiaomi.com>
> ---
>  fs/xfs/xfs_file.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index e33e5e13b95f..4fbe262d33cc 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -24,6 +24,9 @@
>  #include "xfs_pnfs.h"
>  #include "xfs_iomap.h"
>  #include "xfs_reflink.h"
> +#include "xfs_quota.h"
> +#include "xfs_dquot_item.h"
> +#include "xfs_dquot.h"
>  
>  #include <linux/dax.h>
>  #include <linux/falloc.h>
> @@ -803,8 +806,18 @@ xfs_file_buffered_write(
>  		goto write_retry;
>  	} else if (ret == -ENOSPC && !cleared_space) {
>  		struct xfs_icwalk	icw = {0};
> +		struct xfs_dquot	*pdqp = ip->i_pdquot;
>  
>  		cleared_space = true;
> +		if (XFS_IS_PQUOTA_ENFORCED(ip->i_mount) &&
> +			pdqp && xfs_dquot_lowsp(pdqp)) {
> +			xfs_iunlock(ip, iolock);
> +			icw.icw_prid = pdqp->q_id;
> +			icw.icw_flags |= XFS_ICWALK_FLAG_PRID;
> +			xfs_blockgc_free_space(ip->i_mount, &icw);
> +			goto write_retry;
> +		}

This is just duplicating the EDQUOT error handling path for the
specific case that project quota exhaustion returns ENOSPC instead
of EDQUOT.  i.e. the root cause of the problem is that project
quotas are returning ENOSPC rather than EDQUOT, right?

Perhaps we should look at having project quotas return EDQUOT like
the other quotas so we get the project quota block scan done in the
correct places, then convert the error to ENOSPC if we get a second
EDQUOT from the project quota on retry?

-Dave.
-- 
Dave Chinner
david@fromorbit.com