From: Amir Goldstein <amir73il@gmail.com>
To: Jonathan Gilbert <logic@deltaq.org>
Cc: linux-fsdevel@vger.kernel.org, Jan Kara <jack@suse.cz>
Subject: Re: fanotify and files being moved or deleted
Date: Wed, 22 May 2024 08:26:03 +0300 [thread overview]
Message-ID: <CAOQ4uxiMtd80k9N93wjkO13vmmSt5s1333WdSrauGD_-b+rsRQ@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxgOmJjJT=mX96-AwWY_p9fHXtvNZFUcPgqggKgGtpsq9A@mail.gmail.com>
> > > If /home is a bind mount from, say, /data/home/ and you are watching
> > > both /home and /data, you will need to figure out that they are the same
> > > underlying fs and use a mount_fd of /data.
> >
> > My current plan is to discard any mounts which specify a root that is
> > a subpath of another mount, and in the case of multiple mounts of the
> > same root, pick one to move forward with (with hints from
> > configuration) and only mark that one.
> >
>
> You can also use open_by_handle() to determine if one mount
> is a subtree of another.
>
> if you have two fds and two different fhandles from the root of two mounts
> of the same fsid, only one of these commands will result in an fd with
> non empty path:
> fd2inmount1 = open_by_handle_at(mount1_fd, fhandle2, O_PATH);
> fd1inmount2 = open_by_handle_at(mount2_fd, fhandle1, O_PATH);
>
> So you can throw away subtree mounts of the same fsid keeping
> only one mount_fd per fsid as you traverse the mounts.
>
Well ,that's incorrect.
You may have bind mount of non-overlapping subtrees
and you may not have the root mount at all in your mount namespace.
In that case, you can always keep all mount_fd's of a certain fsid and try to
resolve the file handles in each one. Not optimal, but this is the information
we have in events at the moment.
Thanks,
Amir.
prev parent reply other threads:[~2024-05-22 5:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-21 1:03 fanotify and files being moved or deleted Jonathan Gilbert
2024-05-21 3:58 ` Amir Goldstein
2024-05-21 16:03 ` Jonathan Gilbert
2024-05-21 17:13 ` Amir Goldstein
2024-05-21 21:09 ` Jonathan Gilbert
2024-05-22 5:21 ` Amir Goldstein
2024-05-22 5:26 ` Amir Goldstein [this message]
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