[v8,21/32] fanotify: Support enqueueing of error events

Once an error event is triggered, enqueue it in the notification group,
similarly to what is done for other events.  FAN_FS_ERROR is not
handled specially, since the memory is now handled by a preallocated
mempool.

For now, make the event unhashed.  A future patch implements merging of
this kind of event.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v7:
  - WARN_ON -> WARN_ON_ONCE (Amir)
---
 fs/notify/fanotify/fanotify.c | 35 +++++++++++++++++++++++++++++++++++
 fs/notify/fanotify/fanotify.h |  6 ++++++
 2 files changed, 41 insertions(+)

On Tue, Oct 19, 2021 at 3:03 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Once an error event is triggered, enqueue it in the notification group,
> similarly to what is done for other events.  FAN_FS_ERROR is not
> handled specially, since the memory is now handled by a preallocated
> mempool.
>
> For now, make the event unhashed.  A future patch implements merging of
> this kind of event.
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> ---
> Changes since v7:
>   - WARN_ON -> WARN_ON_ONCE (Amir)
> ---
>  fs/notify/fanotify/fanotify.c | 35 +++++++++++++++++++++++++++++++++++
>  fs/notify/fanotify/fanotify.h |  6 ++++++
>  2 files changed, 41 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 01d68dfc74aa..1f195c95dfcd 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -574,6 +574,27 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
>         return &fne->fae;
>  }
>
> +static struct fanotify_event *fanotify_alloc_error_event(
> +                                               struct fsnotify_group *group,
> +                                               __kernel_fsid_t *fsid,
> +                                               const void *data, int data_type)
> +{
> +       struct fs_error_report *report =
> +                       fsnotify_data_error_report(data, data_type);
> +       struct fanotify_error_event *fee;
> +
> +       if (WARN_ON_ONCE(!report))
> +               return NULL;
> +
> +       fee = mempool_alloc(&group->fanotify_data.error_events_pool, GFP_NOFS);
> +       if (!fee)
> +               return NULL;
> +
> +       fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> +
> +       return &fee->fae;
> +}
> +
>  static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
>                                                    u32 mask, const void *data,
>                                                    int data_type, struct inode *dir,
> @@ -641,6 +662,9 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
>
>         if (fanotify_is_perm_event(mask)) {
>                 event = fanotify_alloc_perm_event(path, gfp);
> +       } else if (fanotify_is_error_event(mask)) {
> +               event = fanotify_alloc_error_event(group, fsid, data,
> +                                                  data_type);
>         } else if (name_event && (file_name || child)) {
>                 event = fanotify_alloc_name_event(id, fsid, file_name, child,
>                                                   &hash, gfp);
> @@ -850,6 +874,14 @@ static void fanotify_free_name_event(struct fanotify_event *event)
>         kfree(FANOTIFY_NE(event));
>  }
>
> +static void fanotify_free_error_event(struct fsnotify_group *group,
> +                                     struct fanotify_event *event)
> +{
> +       struct fanotify_error_event *fee = FANOTIFY_EE(event);
> +
> +       mempool_free(fee, &group->fanotify_data.error_events_pool);
> +}
> +
>  static void fanotify_free_event(struct fsnotify_group *group,
>                                 struct fsnotify_event *fsn_event)
>  {
> @@ -873,6 +905,9 @@ static void fanotify_free_event(struct fsnotify_group *group,
>         case FANOTIFY_EVENT_TYPE_OVERFLOW:
>                 kfree(event);
>                 break;
> +       case FANOTIFY_EVENT_TYPE_FS_ERROR:
> +               fanotify_free_error_event(group, event);
> +               break;
>         default:
>                 WARN_ON_ONCE(1);
>         }
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index a577e87fac2b..ebef952481fa 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -298,6 +298,11 @@ static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
>         return container_of(fse, struct fanotify_event, fse);
>  }
>
> +static inline bool fanotify_is_error_event(u32 mask)
> +{
> +       return mask & FAN_FS_ERROR;
> +}
> +
>  static inline bool fanotify_event_has_path(struct fanotify_event *event)
>  {
>         return event->type == FANOTIFY_EVENT_TYPE_PATH ||
> @@ -327,6 +332,7 @@ static inline struct path *fanotify_event_path(struct fanotify_event *event)
>  static inline bool fanotify_is_hashed_event(u32 mask)
>  {
>         return !(fanotify_is_perm_event(mask) ||
> +                fanotify_is_error_event(mask) ||
>                  fsnotify_is_overflow_event(mask));
>  }
>
> --
> 2.33.0
>