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.
Thanks,
Amir.
