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From: Christoph Hellwig <hch@infradead.org>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-fsdevel@vger.kernel.org, jack@suse.com, hch@infradead.org,
	linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	sagi@grimberg.me, avi@scylladb.com, axboe@kernel.dk,
	linux-api@vger.kernel.org, willy@infradead.org,
	tom.leiming@gmail.com, Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 2/8] nowait aio: Introduce RWF_NOWAIT
Date: Thu, 11 May 2017 00:42:18 -0700	[thread overview]
Message-ID: <20170511074218.GB15626@infradead.org> (raw)
In-Reply-To: <20170509122219.31756-3-rgoldwyn@suse.de>

On Tue, May 09, 2017 at 07:22:13AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> This flag informs kernel to bail out if an AIO request will block
> for reasons such as file allocations, or a writeback triggered,
> or would block while allocating requests while performing
> direct I/O.
> 
> Unfortunately, aio_flags is not checked for validity, which would
> break existing applications which have it set to anything besides zero
> or IOCB_FLAG_RESFD. So, we are using aio_reserved1 and renaming it
> to aio_rw_flags.
> 
> RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
> 
> The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
> is called by most filesystems, either through fsops.write_iter() or through
> the function defined by write_iter(). If not, we perform the check defined
> by .write_iter() which is called for direct IO specifically.
> 
> Filesystems xfs, btrfs and ext4 would be supported in the following patches.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
>  fs/9p/vfs_file.c        | 3 +++
>  fs/aio.c                | 6 ++++++
>  fs/ceph/file.c          | 3 +++
>  fs/cifs/file.c          | 3 +++
>  fs/fuse/file.c          | 3 +++
>  fs/nfs/direct.c         | 3 +++
>  fs/ocfs2/file.c         | 3 +++
>  include/linux/fs.h      | 5 ++++-
>  include/uapi/linux/fs.h | 1 +
>  mm/filemap.c            | 3 +++
>  10 files changed, 32 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
> index 3de3b4a89d89..403681db7723 100644
> --- a/fs/9p/vfs_file.c
> +++ b/fs/9p/vfs_file.c
> @@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	loff_t origin;
>  	int err = 0;
>  
> +	if (iocb->ki_flags & IOCB_NOWAIT)
> +		return -EOPNOTSUPP;
> +
>  	retval = generic_write_checks(iocb, from);
>  	if (retval <= 0)
>  		return retval;
> diff --git a/fs/aio.c b/fs/aio.c
> index 020fa0045e3c..ea9f8581d902 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
>  		goto out_put_req;
>  	}
>  
> +	if ((req->common.ki_flags & IOCB_NOWAIT) &&
> +		!(req->common.ki_flags & IOCB_DIRECT)) {

Weird indentation.  Either align after the opening if brace:

	if ((req->common.ki_flags & IOCB_NOWAIT) &&
	    !(req->common.ki_flags & IOCB_DIRECT)) {

or using two tabs:

	if ((req->common.ki_flags & IOCB_NOWAIT) &&
			!(req->common.ki_flags & IOCB_DIRECT)) {

if the first version looks confusing, but never using the same
indentation level as the following code.

Except for that the patch looks fine to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>

  reply	other threads:[~2017-05-11  7:42 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-09 12:22 [PATCH 0/8 v7] No wait AIO Goldwyn Rodrigues
2017-05-09 12:22 ` [PATCH 1/8] Use RWF_* flags for AIO operations Goldwyn Rodrigues
2017-05-11  7:40   ` Christoph Hellwig
2017-05-09 12:22 ` [PATCH 2/8] nowait aio: Introduce RWF_NOWAIT Goldwyn Rodrigues
2017-05-11  7:42   ` Christoph Hellwig [this message]
2017-05-09 12:22 ` [PATCH 3/8] nowait aio: return if direct write will trigger writeback Goldwyn Rodrigues
2017-05-11  7:42   ` Christoph Hellwig
2017-05-09 12:22 ` [PATCH 4/8] nowait-aio: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-05-09 12:22 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
2017-05-11  7:44   ` Christoph Hellwig
     [not found]     ` <20170511074451.GD15626-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-11 18:16       ` Goldwyn Rodrigues
2017-05-09 12:22 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
     [not found]   ` <20170509122219.31756-7-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-09 14:57     ` Jan Kara
2017-05-09 12:22 ` [PATCH 7/8] nowait aio: xfs Goldwyn Rodrigues
2017-05-11  7:45   ` Christoph Hellwig
2017-05-09 12:22 ` [PATCH 8/8] nowait aio: btrfs Goldwyn Rodrigues
  -- strict thread matches above, loose matches on Subject: below --
2017-04-14 12:02 [PATCH 0/8 v6] No wait AIO Goldwyn Rodrigues
2017-04-14 12:02 ` [PATCH 2/8] nowait aio: Introduce RWF_NOWAIT Goldwyn Rodrigues
2017-04-19  6:39   ` Christoph Hellwig
     [not found]     ` <20170419063930.GB20053-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-04-19 10:30       ` Goldwyn Rodrigues
     [not found]         ` <2d816e3e-3625-7ebd-8550-68a7cc9c1a2e-l3A5Bk7waGM@public.gmane.org>
2017-04-19 11:03           ` Jan Kara

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