On Tue, Oct 19, 2021 at 3:03 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> Allow the FAN_FS_ERROR group mempool to grow up to an upper limit
> dynamically, instead of starting already at the limit. This doesn't
> bother resizing on mark removal, but next time a mark is added, the slot
> will be either reused or resized. Also, if several marks are being
> removed at once, most likely the group is going away anyway.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> ---
> fs/notify/fanotify/fanotify_user.c | 26 +++++++++++++++++++++-----
> include/linux/fsnotify_backend.h | 1 +
> 2 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index f77581c5b97f..a860c286e885 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -959,6 +959,10 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
>
> removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
> umask, &destroy_mark);
> +
> + if (removed & FAN_FS_ERROR)
> + group->fanotify_data.error_event_marks--;
> +
> if (removed & fsnotify_conn_mask(fsn_mark->connector))
> fsnotify_recalc_mask(fsn_mark->connector);
> if (destroy_mark)
> @@ -1057,12 +1061,24 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
>
> static int fanotify_group_init_error_pool(struct fsnotify_group *group)
> {
> - if (mempool_initialized(&group->fanotify_data.error_events_pool))
> - return 0;
> + int ret;
> +
> + if (group->fanotify_data.error_event_marks >=
> + FANOTIFY_DEFAULT_MAX_FEE_POOL)
> + return -ENOMEM;
>
> - return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
> - FANOTIFY_DEFAULT_MAX_FEE_POOL,
> - sizeof(struct fanotify_error_event));
> + if (!mempool_initialized(&group->fanotify_data.error_events_pool))
> + ret = mempool_init_kmalloc_pool(
> + &group->fanotify_data.error_events_pool,
> + 1, sizeof(struct fanotify_error_event));
> + else
> + ret = mempool_resize(&group->fanotify_data.error_events_pool,
> + group->fanotify_data.error_event_marks + 1);
> +
> + if (!ret)
> + group->fanotify_data.error_event_marks++;
> +
> + return ret;
> }
This is not what I had in mind.
I was thinking start with ~32 and double each time limit is reached.
And also, this code grows the pool to infinity with add/remove mark loop.
Anyway, since I clearly did not understand how mempool works and
Jan had some different ideas I would leave it to Jan to explain
how he wants the mempool init limit and resize to be implemented.
Thanks,
Amir.
