linux-kernel - Re: [PATCH] splice: Fix filemap of a blockdev

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Date:   Wed, 19 Apr 2023 16:47:08 +0530
From:   "Jain, Ayush" <ayush.jain3@....com>
To:     David Howells <dhowells@...hat.com>, Jens Axboe <axboe@...nel.dk>
Cc:     Christoph Hellwig <hch@....de>, Al Viro <viro@...iv.linux.org.uk>,
        David Hildenbrand <david@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        Steve French <stfrench@...rosoft.com>, linux-mm@...ck.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] splice: Fix filemap of a blockdev

Hello David,

This resolves the Fio-test issue that i reported in
Link: https://lore.kernel.org/r/0c6b661c-f7ff-cf12-b7f0-00b6b2f1317b@amd.com/

On 4/19/2023 2:24 PM, David Howells wrote:
> Fix the new filemap_splice_read() function to get i_size from
> in->f_mapping->host, not in->f_inode so that it works with block devices
> too (in->f_inode points to the device file, which is typically zero size).
> 
> Fixes: 07073eb01c5f ("splice: Add a func to do a splice from a buffered file without ITER_PIPE")
> Link: https://lore.kernel.org/r/0c6b661c-f7ff-cf12-b7f0-00b6b2f1317b@amd.com/
> Reported-by: Ayush Jain <ayush.jain3@....com>

Tested-by: Ayush Jain <ayush.jain3@....com>

> cc: Jens Axboe <axboe@...nel.dk>
> cc: Christoph Hellwig <hch@....de>
> cc: Al Viro <viro@...iv.linux.org.uk>
> cc: David Hildenbrand <david@...hat.com>
> cc: John Hubbard <jhubbard@...dia.com>
> cc: Steve French <stfrench@...rosoft.com>
> cc: linux-mm@...ck.org
> cc: linux-block@...r.kernel.org
> cc: linux-fsdevel@...r.kernel.org
> ---
>   mm/filemap.c |    4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 470be06b6096..f86cc8acf33a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2902,7 +2902,7 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
>   	do {
>   		cond_resched();
>   
> -		if (*ppos >= i_size_read(file_inode(in)))
> +		if (*ppos >= i_size_read(in->f_mapping->host))
>   			break;
>   
>   		iocb.ki_pos = *ppos;
> @@ -2918,7 +2918,7 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
>   		 * part of the page is not copied back to userspace (unless
>   		 * another truncate extends the file - this is desired though).
>   		 */
> -		isize = i_size_read(file_inode(in));
> +		isize = i_size_read(in->f_mapping->host);
>   		if (unlikely(*ppos >= isize))
>   			break;
>   		end_offset = min_t(loff_t, isize, *ppos + len);
> 

Regards,
Ayush Jain