On Tue, Oct 19, 2021 at 3:01 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> FAN_FS_ERROR allows events without inodes - i.e. for file system-wide
> errors. Even though fsnotify_handle_inode_event is not currently used
> by fanotify, this patch protects this path to handle this new case.
>
> Suggested-by: Amir Goldstein <amir73il@xxxxxxxxx>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> ---
> fs/notify/fsnotify.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> index fde3a1115a17..47f931fb571c 100644
> --- a/fs/notify/fsnotify.c
> +++ b/fs/notify/fsnotify.c
> @@ -252,6 +252,9 @@ static int fsnotify_handle_inode_event(struct fsnotify_group *group,
> if (WARN_ON_ONCE(!ops->handle_inode_event))
> return 0;
>
> + if (!inode)
> + return 0;
> +
Sigh.. the plot thickens.
There are three in-tree backends that implement the ->handle_inode_event()
interface.
inotify and dnotify can take NULL inode and the above will make the CREATE
events on kernfs vanish, so we cannot do that.
Sorry for not noticing this earlier when I asked for this change.
nfsd_file_fsnotify_handle_event() can most certainly not take NULL inode,
but nfsd does not watch for CREATE events.
I think what we need to do is (Jan please correct me if you think otherwise):
1. Document the handle_inode_event() interface that either inode or dir
must be non-NULL
2. WARN_ON_ONCE(!inode && !dir) instead of just (!inode) above
3. Add WARN_ON_ONCE(!inode) before trace_nfsd_file_fsnotify_handle_event()
in nfsd_file_fsnotify_handle_event()
Apologies, Gabriel, for having to cleanup our mess ;-)
Thanks,
Amir.
