linux-kernel - Re: [PATCH v2 3/8] vfs: Add O_DENYREAD/WRITE flags support for open syscall

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Message-ID: <CAKywueQDtjTxDF4-pcoBaJfXGS7Q+mvf+Jk3KE=2US=gFn_vTQ@mail.gmail.com>
Date:	Thu, 7 Feb 2013 20:50:16 +0400
From:	Pavel Shilovsky <piastry@...rsoft.ru>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-cifs@...r.kernel.org, linux-nfs@...r.kernel.org,
	wine-devel@...ehq.org
Subject: Re: [PATCH v2 3/8] vfs: Add O_DENYREAD/WRITE flags support for open syscall

2013/2/7 J. Bruce Fields <bfields@...ldses.org>:
> That would be a bug, I think.  E.g. "man 3posix open":
>
>         No  files  shall  be created or modified if the function returns
>         -1.
>
> Looking at the code...  See the references to FILE_CREATED in
> atomic_open--looks like that's trying to prevent may_open from failing
> in this case.
>
>> I think
>> there is no difference between this case and the situation with
>> deny_lock_file there.
>
> Looks to me like it would be a bug in either case.

Then we returned from lookup_open in do_last we go to 'opened' lable.
Then we have a 3(!) chances to return -1 while a file is created
(open_check_o_direct, ima_file_check, handle_truncate). In this case
these places are bugs too.

We can call vfs_unlink if we failed after a file was created, but
possible affects need to be investigated.

-- 
Best regards,
Pavel Shilovsky.
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