Re: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

[Dave Chinner <david@fromorbit.com>]

On Wed, Jul 26, 2023 at 06:25:58PM +0800, Hao Xu wrote:
> From: Hao Xu <howeyxu@tencent.com>
> 
> To support nowait llseek(), IOMAP_NOWAIT semantics should be respected.
> In xfs, xfs_seek_iomap_begin() is the only place which may be blocked
> by ilock and extent loading. Let's turn it into trylock logic just like
> what we've done in xfs_readdir().
> 
> Signed-off-by: Hao Xu <howeyxu@tencent.com>
> ---
>  fs/xfs/xfs_iomap.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 18c8f168b153..bbd7c6b27701 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1294,7 +1294,9 @@ xfs_seek_iomap_begin(
>  	if (xfs_is_shutdown(mp))
>  		return -EIO;
>  
> -	lockmode = xfs_ilock_data_map_shared(ip);
> +	lockmode = xfs_ilock_data_map_shared_generic(ip, flags & IOMAP_NOWAIT);

What does this magic XFS function I can't find anywhere in this
patch set do?

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