linux-ext4 - Re: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap

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Date:   Thu, 27 Jul 2023 07:55:47 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Hao Xu <hao.xu@...ux.dev>
Cc:     io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Pavel Begunkov <asml.silence@...il.com>,
        Christian Brauner <brauner@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Stefan Roesch <shr@...com>, Clay Harris <bugs@...ycon.org>,
        "Darrick J . Wong" <djwong@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, Wanpeng Li <wanpengli@...cent.com>
Subject: Re: [PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

On Wed, Jul 26, 2023 at 06:25:58PM +0800, Hao Xu wrote:
> From: Hao Xu <howeyxu@...cent.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@...cent.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@...morbit.com