linux-kernel - Re: Commit edf064e7c (btrfs: nowait aio support) breaks shells

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Message-ID: <db94b5f7-d3a1-2340-0758-9437193d8254@suse.de>
Date:   Tue, 4 Jul 2017 10:31:55 -0500
From:   Goldwyn Rodrigues <rgoldwyn@...e.de>
To:     Markus Trippelsdorf <markus@...ppelsdorf.de>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-btrfs@...r.kernel.org
Cc:     David Sterba <dsterba@...e.com>, Jens Axboe <axboe@...nel.dk>
Subject: Re: Commit edf064e7c (btrfs: nowait aio support) breaks shells



On 07/04/2017 02:45 AM, Markus Trippelsdorf wrote:
> On 2017.07.04 at 06:23 +0200, Markus Trippelsdorf wrote:
>> commit edf064e7c6fec3646b06c944a8e35d1a3de5c2c3 (HEAD, refs/bisect/bad)
>> Author: Goldwyn Rodrigues <rgoldwyn@...e.com>
>> Date:   Tue Jun 20 07:05:49 2017 -0500
>>
>>     btrfs: nowait aio support
>>
>> apparently breaks several shell related features on my system.
> 
> Here is a simple testcase:
> 
>  % echo "foo" >> test
>  % echo "foo" >> test
>  % cat test
>  foo
>  %
> 

Thanks for testing.
Yes, pos must be set with iocb->ki_pos for appends. I should not have
removed the initialization. Could you try this patch?

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 59e2dccdf75b..7947781229e5 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1931,6 +1931,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb
*iocb,
 	 */
 	update_time_for_write(inode);

+	pos = iocb->ki_pos;
 	start_pos = round_down(pos, fs_info->sectorsize);
 	oldsize = i_size_read(inode);
 	if (start_pos > oldsize) {



-- 
Goldwyn