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From: Jan Kara <jack@suse.cz>
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,
	axboe@kernel.dk, linux-api@vger.kernel.org,
	adam.manzanares@wdc.com, viro@zeniv.linux.org.uk,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 05/10] fs: return if direct write will trigger writeback
Date: Thu, 25 May 2017 10:32:32 +0200	[thread overview]
Message-ID: <20170525083232.GF28950@quack2.suse.cz> (raw)
In-Reply-To: <20170524164150.9492-6-rgoldwyn@suse.de>

On Wed 24-05-17 11:41:45, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Find out if the write will trigger a wait due to writeback. If yes,
> return -EAGAIN.
> 
> Return -EINVAL for buffered AIO: there are multiple causes of
> delay such as page locks, dirty throttling logic, page loading
> from disk etc. which cannot be taken care of.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  mm/filemap.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 097213275461..bc146efa6815 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2675,6 +2675,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
>  
>  	pos = iocb->ki_pos;
>  
> +	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
> +		return -EINVAL;
> +
>  	if (limit != RLIM_INFINITY) {
>  		if (iocb->ki_pos >= limit) {
>  			send_sig(SIGXFSZ, current, 0);
> @@ -2743,9 +2746,17 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
>  	write_len = iov_iter_count(from);
>  	end = (pos + write_len - 1) >> PAGE_SHIFT;
>  
> -	written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
> -	if (written)
> -		goto out;
> +	if (iocb->ki_flags & IOCB_NOWAIT) {
> +		/* If there are pages to writeback, return */
> +		if (filemap_range_has_page(inode->i_mapping, pos,
> +					   pos + iov_iter_count(from)))
> +			return -EAGAIN;
> +	} else {
> +		written = filemap_write_and_wait_range(mapping, pos,
> +							pos + write_len - 1);
> +		if (written)
> +			goto out;
> +	}
>  
>  	/*
>  	 * After a write we want buffered reads to be sure to go to disk to get
> -- 
> 2.12.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2017-05-25  8:32 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-24 16:41 [PATCH 0/10 v9] No wait AIO Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 01/10] fs: Separate out kiocb flags setup based on RWF_* flags Goldwyn Rodrigues
2017-05-25  8:16   ` Jan Kara
2017-05-24 16:41 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-05-25  8:25   ` Jan Kara
     [not found] ` <20170524164150.9492-1-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-24 16:41   ` [PATCH 03/10] fs: Use RWF_* flags for AIO operations Goldwyn Rodrigues
2017-05-25  8:27     ` Jan Kara
2017-05-24 16:41   ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues
2017-05-25  8:32     ` Jan Kara [this message]
2017-05-28  9:27   ` [PATCH 0/10 v9] No wait AIO Christoph Hellwig
2017-05-29  2:38     ` Goldwyn Rodrigues
2017-05-29  8:32       ` Christoph Hellwig
2017-05-24 16:41 ` [PATCH 04/10] fs: Introduce RWF_NOWAIT Goldwyn Rodrigues
2017-05-25  8:30   ` Jan Kara
2017-05-24 16:41 ` [PATCH 06/10] fs: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-05-25  8:33   ` Jan Kara
2017-05-24 16:41 ` [PATCH 07/10] fs: return on congested block device Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 08/10] ext4: nowait aio support Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 09/10] xfs: " Goldwyn Rodrigues
2017-05-24 16:49   ` Darrick J. Wong
     [not found]   ` <20170524164150.9492-10-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-28  9:31     ` Christoph Hellwig
2017-05-29  2:38       ` Goldwyn Rodrigues
2017-05-29  8:21         ` Jan Kara
2017-05-29  8:33         ` Christoph Hellwig
     [not found]           ` <20170529083338.GC1899-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-30 16:13             ` Goldwyn Rodrigues
2017-05-31  8:51               ` Jan Kara
2017-05-24 16:41 ` [PATCH 10/10] btrfs: " Goldwyn Rodrigues
  -- strict thread matches above, loose matches on Subject: below --
2017-06-15 15:59 [PATCH 0/10 v12] No wait AIO Goldwyn Rodrigues
2017-06-15 15:59 ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues
2017-06-06 11:19 [PATCH 0/10 v11] No wait AIO Goldwyn Rodrigues
2017-06-06 11:19 ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues
2017-06-05  5:35 [PATCH 0/10 v10] No wait AIO Goldwyn Rodrigues
2017-06-05  5:35 ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues
2017-05-11 19:17 [PATCH 0/10 v8] No wait AIO Goldwyn Rodrigues
2017-05-11 19:17 ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues

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