Re: [PATCH 12/29] xfs: enforce GFP_NOIO implicitly during nowait time update

Matthew Wilcox
2023-08-25T14:20:53Z

On Fri, Aug 25, 2023 at 09:54:14PM +0800, Hao Xu wrote:
> +++ b/fs/xfs/xfs_iops.c
> @@ -1037,6 +1037,8 @@ xfs_vn_update_time(
> int log_flags = XFS_ILOG_TIMESTAMP;
> struct xfs_trans *tp;
> int error;
> + int old_pflags;
> + bool nowait = flags & S_NOWAIT;
>
> trace_xfs_update_time(ip);
>
> @@ -1049,13 +1051,18 @@ xfs_vn_update_time(
> log_flags |= XFS_ILOG_CORE;
> }
>
> + if (nowait)
> + old_pflags = memalloc_noio_save();
> +
> error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);

This is an abuse of the memalloc_noio_save() interface. You shouldn't
be setting it around individual allocations; it's the part of the kernel
which decides "I can't afford to do I/O" that should be setting it.
In this case, it should probably be set by io_uring, way way way up at
the top.

But Jens didn't actually answer my question about that: