Subject: Re: [PATCH 02/12] buffer: grow_dev_page() should use __GFP_NOFAIL for
 all cases
To: Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Cc: hannes@cmpxchg.org, jack@suse.cz, torvalds@linux-foundation.org
References: <1506543239-31470-1-git-send-email-axboe@kernel.dk>
 <1506543239-31470-3-git-send-email-axboe@kernel.dk>
From: Nikolay Borisov <nborisov@suse.com>
Message-ID: <3ddbf81d-7894-920d-cfa3-47ec17c87af8@suse.com>
Date: Thu, 28 Sep 2017 17:11:04 +0300
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On 27.09.2017 23:13, Jens Axboe wrote:
> We currently it it for find_or_create_page(), which means that it

nit: Perhaps you wanted to write "We currently use it for find_..."

otherwise:

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> cannot fail. Ensure we also pass in 'retry == true' to
> alloc_page_buffers(), which also ensure that it cannot fail.
> 
> After this, there are no failure cases in grow_dev_page() that
> occur because of a failed memory allocation.
> 
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  fs/buffer.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 1234ae343aef..3b60cd8456db 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -988,8 +988,6 @@ grow_dev_page(struct block_device *bdev, sector_t block,
>  	gfp_mask |= __GFP_NOFAIL;
>  
>  	page = find_or_create_page(inode->i_mapping, index, gfp_mask);
> -	if (!page)
> -		return ret;
>  
>  	BUG_ON(!PageLocked(page));
>  
> @@ -1008,9 +1006,7 @@ grow_dev_page(struct block_device *bdev, sector_t block,
>  	/*
>  	 * Allocate some buffers for this page
>  	 */
> -	bh = alloc_page_buffers(page, size, false);
> -	if (!bh)
> -		goto failed;
> +	bh = alloc_page_buffers(page, size, true);
>  
>  	/*
>  	 * Link the page to the buffers and initialise them.  Take the
>