2018-02-09 23:45 GMT+01:00 Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>:
> On 09.02.2018 23:56, Andrew Morton wrote:
>> On Fri, 9 Feb 2018 18:04:54 +0300 Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> wrote:
>>
>>> Watch descriptor is id of the watch created by inotify_add_watch().
>>> It is allocated in inotify_add_to_idr(), and takes the numbers
>>> starting from 1. Every new inotify watch obtains next available
>>> number (usually, old + 1), as served by idr_alloc_cyclic().
>>>
>>> CRIU (Checkpoint/Restore In Userspace) project supports inotify
>>> files, and restores watched descriptors with the same numbers,
>>> they had before dump. Since there was no kernel support, we
>>> had to use cycle to add a watch with specific descriptor id:
>>>
>>> while (1) {
>>> int wd;
>>>
>>> wd = inotify_add_watch(inotify_fd, path, mask);
>>> if (wd < 0) {
>>> break;
>>> } else if (wd == desired_wd_id) {
>>> ret = 0;
>>> break;
>>> }
>>>
>>> inotify_rm_watch(inotify_fd, wd);
>>> }
>>>
>>> (You may find the actual code at the below link:
>>> https://github.com/checkpoint-restore/criu/blob/v3.7/criu/fsnotify.c#L577)
Well using a ioctl command to force a specific wd is possible, but
isn't it also possible
to do a "freeze" of all (inotify) watches which are involved, and
"unfreeze" when restoring?
Stef
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