[CRIU] [PATCH] files: check fd flags after restore
Pavel Emelyanov
xemul at parallels.com
Tue Dec 15 03:50:16 PST 2015
On 12/15/2015 02:37 PM, Stanislav Kinsburskiу wrote:
>
> 15 дек. 2015 г. 12:31 PM пользователь Pavel Emelyanov <xemul at parallels.com> написал:
>>
>> On 12/14/2015 06:19 PM, Stanislav Kinsburskiy wrote:
>>> System call sys_fcntl() in _some_ kernels can silently drop some flags during
>>> set and return success code.
>>
>> What are these flags?
>>
>
> O_DIRECT and O_SYNC. Feature of openvz kernel.
OK, don't we break restore on those kernels with this patch then?
>>> This patch adds double check, that all the fd flags were really set.
>>>
>>> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
>>> ---
>>> files.c | 11 +++++++++++
>>> 1 file changed, 11 insertions(+)
>>>
>>> diff --git a/files.c b/files.c
>>> index a27667d..751a9a9 100644
>>> --- a/files.c
>>> +++ b/files.c
>>> @@ -741,6 +741,17 @@ int set_fd_flags(int fd, int flags)
>>> ret = fcntl(fd, F_SETFL, flags);
>>> if (ret < 0)
>>> goto err;
>>> +
>>> + /* Let's check, that now actual flags contains those we need */
>>> + ret = fcntl(fd, F_GETFL, 0);
>>> + if (ret < 0)
>>> + goto err;
>>> +
>>> + if (ret != flags) {
>>> + pr_err("fcntl call on fd %d (flags %#o) succeeded, "
>>> + "but some flags were dropped: %#o\n", fd, flags, ret);
>>> + return -1;
>>> + }
>>> return 0;
>>>
>>> err:
>>>
>>> _______________________________________________
>>> CRIU mailing list
>>> CRIU at openvz.org
>>> https://lists.openvz.org/mailman/listinfo/criu
>>> .
>>>
>>
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