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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org
Subject: Re: [PATCH 3/3] ext4: readpages() should submit IO as read-ahead
Date: Thu, 24 May 2018 16:47:30 -0400	[thread overview]
Message-ID: <20180524204730.GC7712@thunk.org> (raw)
In-Reply-To: <1527177774-21414-4-git-send-email-axboe@kernel.dk>

On Thu, May 24, 2018 at 10:02:54AM -0600, Jens Axboe wrote:
> a_ops->readpages() is only ever used for read-ahead. Ensure that we
> pass this information down to the block layer.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  fs/ext4/readpage.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
> index 9ffa6fad18db..92b28273b223 100644
> --- a/fs/ext4/readpage.c
> +++ b/fs/ext4/readpage.c
> @@ -259,7 +259,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
>  			bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
>  			bio->bi_end_io = mpage_end_io;
>  			bio->bi_private = ctx;
> -			bio_set_op_attrs(bio, REQ_OP_READ, 0);
> +			bio_set_op_attrs(bio, REQ_OP_READ, REQ_RAHEAD);
>  		}

The problem is that ext4_readpage() also calls ext4_mpage_readpages().
So you can't set REQ_RAHEAD unconditionally here.

							- Ted

  reply	other threads:[~2018-05-24 20:47 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-24 16:02 [PATCHSET 0/3] Submit ->readpages() " Jens Axboe
2018-05-24 16:02 ` [PATCH 1/3] mpage: mpage_readpages() should submit " Jens Axboe
2018-05-24 19:43   ` Andrew Morton
2018-05-24 19:57     ` Matthew Wilcox
2018-05-24 20:24       ` Jens Axboe
2018-05-29 14:36     ` Jens Axboe
2018-05-29 21:59       ` Andrew Morton
2018-05-29 22:18         ` Jens Axboe
2018-05-29 22:37           ` Jens Axboe
2018-05-24 16:02 ` [PATCH 2/3] btrfs: readpages() " Jens Axboe
2018-05-24 16:02 ` [PATCH 3/3] ext4: " Jens Axboe
2018-05-24 20:47   ` Theodore Y. Ts'o [this message]
2018-05-24 20:53     ` Jens Axboe
2018-05-24 21:05       ` Jens Axboe
2018-05-25  8:32 ` [PATCHSET 0/3] Submit ->readpages() " Christoph Hellwig
2018-05-25 14:21   ` Jens Axboe

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