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References: <20210615235556.970928-1-krisman@collabora.com> <20210615235556.970928-4-krisman@collabora.com>
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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Wed, 16 Jun 2021 11:07:18 +0300
Message-ID: <CAOQ4uxhNku-QG8ubKqrTUNFy=FbpwJabFznKOD7tkuxMqxkj9g@mail.gmail.com>
Subject: Re: [PATCH v2 03/14] fanotify: Split fsid check from other fid mode checks
To:     Gabriel Krisman Bertazi <krisman@collabora.com>
Cc:     kernel@collabora.com, "Darrick J. Wong" <djwong@kernel.org>,
        Theodore Tso <tytso@mit.edu>,
        Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.com>,
        David Howells <dhowells@redhat.com>,
        Khazhismel Kumykov <khazhy@google.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Ext4 <linux-ext4@vger.kernel.org>
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On Wed, Jun 16, 2021 at 2:56 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> FAN_ERROR will require fsid, but not necessarily require the filesystem

FAN_FS_ERROR

> to expose a file handle.  Split those checks into different functions, so
> they can be used separately when setting up an event.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>
> ---
> Changes since v1:
>   (Amir)
>   - Sort hunks to simplify diff.
> Changes since RFC:
>   (Amir)
>   - Rename fanotify_check_path_fsid -> fanotify_test_fsid.
>   - Use dentry directly instead of path.
> ---
>  fs/notify/fanotify/fanotify_user.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 0da4e5dcab0f..af518790a80f 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1192,16 +1192,15 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
>         return fd;
>  }
>
> -/* Check if filesystem can encode a unique fid */
> -static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
> +static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
>  {
>         __kernel_fsid_t root_fsid;
>         int err;
>
>         /*
> -        * Make sure path is not in filesystem with zero fsid (e.g. tmpfs).
> +        * Make sure dentry is not of a filesystem with zero fsid (e.g. tmpfs).

Sorry.... I forgot to update this comment
59cda49ecf6c ("shmem: allow reporting fanotify events with file
handles on tmpfs")
Not your fault, but best we fix the comment if we change it to be correct.
It can be changed to (e.g. fuse)

Thanks,
Amir.