On Fri, Oct 15, 2021 at 9:19 AM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> On Fri, Oct 15, 2021 at 12:39 AM Gabriel Krisman Bertazi
> <krisman@xxxxxxxxxxxxx> wrote:
> >
> > Error reporting needs to be done in an atomic context. This patch
> > introduces a group-wide mempool of error events, shared by all
> > marks in this group.
> >
> > Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> > ---
> > fs/notify/fanotify/fanotify.c | 3 +++
> > fs/notify/fanotify/fanotify.h | 11 +++++++++++
> > fs/notify/fanotify/fanotify_user.c | 26 +++++++++++++++++++++++++-
> > include/linux/fsnotify_backend.h | 2 ++
> > 4 files changed, 41 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> > index 8f152445d75c..01d68dfc74aa 100644
> > --- a/fs/notify/fanotify/fanotify.c
> > +++ b/fs/notify/fanotify/fanotify.c
> > @@ -819,6 +819,9 @@ static void fanotify_free_group_priv(struct fsnotify_group *group)
> > if (group->fanotify_data.ucounts)
> > dec_ucount(group->fanotify_data.ucounts,
> > UCOUNT_FANOTIFY_GROUPS);
> > +
> > + if (mempool_initialized(&group->fanotify_data.error_events_pool))
> > + mempool_exit(&group->fanotify_data.error_events_pool);
> > }
> >
> > static void fanotify_free_path_event(struct fanotify_event *event)
> > diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> > index c42cf8fd7d79..a577e87fac2b 100644
> > --- a/fs/notify/fanotify/fanotify.h
> > +++ b/fs/notify/fanotify/fanotify.h
> > @@ -141,6 +141,7 @@ enum fanotify_event_type {
> > FANOTIFY_EVENT_TYPE_PATH,
> > FANOTIFY_EVENT_TYPE_PATH_PERM,
> > FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
> > + FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
> > __FANOTIFY_EVENT_TYPE_NUM
> > };
> >
> > @@ -196,6 +197,16 @@ FANOTIFY_NE(struct fanotify_event *event)
> > return container_of(event, struct fanotify_name_event, fae);
> > }
> >
> > +struct fanotify_error_event {
> > + struct fanotify_event fae;
> > +};
> > +
> > +static inline struct fanotify_error_event *
> > +FANOTIFY_EE(struct fanotify_event *event)
> > +{
> > + return container_of(event, struct fanotify_error_event, fae);
> > +}
> > +
> > static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
> > {
> > if (event->type == FANOTIFY_EVENT_TYPE_FID)
> > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> > index 66ee3c2805c7..f1cf863d6f9f 100644
> > --- a/fs/notify/fanotify/fanotify_user.c
> > +++ b/fs/notify/fanotify/fanotify_user.c
> > @@ -30,6 +30,7 @@
> > #define FANOTIFY_DEFAULT_MAX_EVENTS 16384
> > #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192
> > #define FANOTIFY_DEFAULT_MAX_GROUPS 128
> > +#define FANOTIFY_DEFAULT_FEE_POOL 32
> >
>
> We can probably start with a more generous pool (128?)
> It doesn't cost that much.
> But anyway, I think this pool needs to auto-grow (up to a maximum size)
> instead of having a rigid arbitrary limit.
>
As long as the pool grows, I don't mind if it start at size 32,
but I just noticed that mempools cannot be accounted to memcg??
Then surely the maximum size need to be kept pretty low.
Thanks,
Amir.
