linux-ext4 - Re: [PATCH 1/8] Use RWF_* flags for AIO operations

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Date:   Tue, 18 Apr 2017 23:37:54 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Goldwyn Rodrigues <rgoldwyn@...e.de>
Cc:     linux-fsdevel@...r.kernel.org, jack@...e.com, hch@...radead.org,
        linux-block@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        sagi@...mberg.me, avi@...lladb.com, axboe@...nel.dk,
        linux-api@...r.kernel.org, willy@...radead.org,
        tom.leiming@...il.com, Goldwyn Rodrigues <rgoldwyn@...e.com>
Subject: Re: [PATCH 1/8] Use RWF_* flags for AIO operations

On Fri, Apr 14, 2017 at 07:02:50AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@...e.com>
> 
> RWF_* flags is used for preadv2/pwritev2 calls. Port to use
> it for aio operations as well. For this, aio_rw_flags is
> introduced in struct iocb (using aio_reserved1) which will
> carry these flags.
> 
> This is a precursor to the nowait AIO calls.
> 
> Note, the only place RWF_HIPRI comes in effect is dio_await_one().
> All the rest of the locations, aio code return -EIOCBQUEUED before the
> checks for RWF_HIPRI.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@...e.com>
> ---
>  fs/aio.c                     | 10 +++++++++-
>  fs/read_write.c              |  7 +------
>  include/linux/fs.h           | 12 ++++++++++++
>  include/uapi/linux/aio_abi.h |  2 +-
>  4 files changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/aio.c b/fs/aio.c
> index f52d925ee259..b8a33f5beef5 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1541,11 +1541,17 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
>  	ssize_t ret;
>  
>  	/* enforce forwards compatibility on users */
> -	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
> +	if (unlikely(iocb->aio_reserved2)) {
>  		pr_debug("EINVAL: reserve field set\n");
>  		return -EINVAL;
>  	}
>  
> +	if (unlikely(iocb->aio_rw_flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))) {
> +		pr_debug("EINVAL: aio_rw_flags set with incompatible flags\n");
> +		return -EINVAL;
> +	}
> +

> +	req->common.ki_flags |= iocb_rw_flags(iocb->aio_rw_flags);

The flag validity checking also needs to go into what's currently
iocb_rw_flags (which will need a new name and a return value).