linux-ext4 - Re: [PATCH RFC 01/15] fanotify: Fold event size calculation to its own function

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Date:   Tue, 27 Apr 2021 07:42:27 +0300
From:   Amir Goldstein <amir73il@...il.com>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     Theodore Tso <tytso@....edu>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.com>,
        David Howells <dhowells@...hat.com>,
        Khazhismel Kumykov <khazhy@...gle.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Ext4 <linux-ext4@...r.kernel.org>, kernel@...labora.com
Subject: Re: [PATCH RFC 01/15] fanotify: Fold event size calculation to its
 own function

On Mon, Apr 26, 2021 at 9:42 PM Gabriel Krisman Bertazi
<krisman@...labora.com> wrote:
>
> Every time this function is invoked, it is immediately added to
> FAN_EVENT_METADATA_LEN, since there is no need to just calculate the
> length of info records. This minor clean up folds the rest of the
> calculation into the function, which now operates in terms of events,
> returning the size of the entire event, including metadata.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

Nice

Reviewed-by: Amir Goldstein <amir73il@...il.com>

> ---
>  fs/notify/fanotify/fanotify_user.c | 40 +++++++++++++++++-------------
>  1 file changed, 23 insertions(+), 17 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 9e0c1afac8bd..0332c4afeec3 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -64,17 +64,24 @@ static int fanotify_fid_info_len(int fh_len, int name_len)
>         return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN);
>  }
>
> -static int fanotify_event_info_len(unsigned int fid_mode,
> -                                  struct fanotify_event *event)
> +static size_t fanotify_event_len(struct fanotify_event *event,
> +                                unsigned int fid_mode)
>  {
> -       struct fanotify_info *info = fanotify_event_info(event);
> -       int dir_fh_len = fanotify_event_dir_fh_len(event);
> -       int fh_len = fanotify_event_object_fh_len(event);
> -       int info_len = 0;
> +       size_t event_len = FAN_EVENT_METADATA_LEN;
> +       struct fanotify_info *info;
> +       int dir_fh_len;
> +       int fh_len;
>         int dot_len = 0;
>
> +       if (!fid_mode)
> +               return event_len;
> +
> +       info = fanotify_event_info(event);
> +       dir_fh_len = fanotify_event_dir_fh_len(event);
> +       fh_len = fanotify_event_object_fh_len(event);
> +
>         if (dir_fh_len) {
> -               info_len += fanotify_fid_info_len(dir_fh_len, info->name_len);
> +               event_len += fanotify_fid_info_len(dir_fh_len, info->name_len);
>         } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) {
>                 /*
>                  * With group flag FAN_REPORT_NAME, if name was not recorded in
> @@ -84,9 +91,9 @@ static int fanotify_event_info_len(unsigned int fid_mode,
>         }
>
>         if (fh_len)
> -               info_len += fanotify_fid_info_len(fh_len, dot_len);
> +               event_len += fanotify_fid_info_len(fh_len, dot_len);
>
> -       return info_len;
> +       return event_len;
>  }
>
>  /*
> @@ -98,7 +105,8 @@ static int fanotify_event_info_len(unsigned int fid_mode,
>  static struct fanotify_event *get_one_event(struct fsnotify_group *group,
>                                             size_t count)
>  {
> -       size_t event_size = FAN_EVENT_METADATA_LEN;
> +       size_t event_size;
> +       struct fsnotify_event *fse;
>         struct fanotify_event *event = NULL;
>         unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
>
> @@ -108,16 +116,15 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
>         if (fsnotify_notify_queue_is_empty(group))
>                 goto out;
>
> -       if (fid_mode) {
> -               event_size += fanotify_event_info_len(fid_mode,
> -                       FANOTIFY_E(fsnotify_peek_first_event(group)));
> -       }
> +       fse = fsnotify_peek_first_event(group);
> +       event = FANOTIFY_E(fse);
> +       event_size = fanotify_event_len(event, fid_mode);
>
>         if (event_size > count) {
>                 event = ERR_PTR(-EINVAL);
>                 goto out;
>         }
> -       event = FANOTIFY_E(fsnotify_remove_first_event(group));
> +       fsnotify_remove_queued_event(group, fse);
>         if (fanotify_is_perm_event(event->mask))
>                 FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
>  out:
> @@ -334,8 +341,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
>
>         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
>
> -       metadata.event_len = FAN_EVENT_METADATA_LEN +
> -                               fanotify_event_info_len(fid_mode, event);
> +       metadata.event_len = fanotify_event_len(event, fid_mode);
>         metadata.metadata_len = FAN_EVENT_METADATA_LEN;
>         metadata.vers = FANOTIFY_METADATA_VERSION;
>         metadata.reserved = 0;
> --
> 2.31.0
>