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

Goldwyn Rodrigues
2017-07-04T15:31:49Z

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@suse.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