From: Al Viro <viro@zeniv.linux.org.uk>
To: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: avagin@gmail.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] fsopen: fsconfig syscall restart fix
Date: Wed, 23 Sep 2020 18:03:22 +0100 [thread overview]
Message-ID: <20200923170322.GP3421308@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200923164637.13032-2-alexander.mikhalitsyn@virtuozzo.com>
On Wed, Sep 23, 2020 at 07:46:36PM +0300, Alexander Mikhalitsyn wrote:
> During execution of vfs_fsconfig_locked function we can get ERESTARTNOINTR
> error (or other interrupt error). But we changing fs context fc->phase
> field to transient states and our entry fc->phase checks in switch cases
> (see FS_CONTEXT_CREATE_PARAMS, FS_CONTEXT_RECONF_PARAMS) will always fail
> after syscall restart which will lead to returning -EBUSY to the userspace.
>
> The idea of the fix is to save entry-time fs_context phase field value and
> recover fc->phase value to the original one before exiting with
> "interrupt error" (ERESTARTNOINTR or similar).
If you have e.g. vfs_create_tree() fail in the middle of ->get_tree(),
the only thing you can do to that thing is to discard it. The state is
*NOT* required to be recoverable after a failure exit - quite a bit of
config might've been consumed and freed by that point.
CREATE and RECONFIGURE are simply not restartable.
next prev parent reply other threads:[~2020-09-23 17:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 16:46 [PATCH 0/1] fsopen: fsconfig syscall restart fix Alexander Mikhalitsyn
2020-09-23 16:46 ` [PATCH 1/1] " Alexander Mikhalitsyn
2020-09-23 17:03 ` Al Viro [this message]
2020-09-23 17:19 ` Alexander Mikhalitsyn
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