On Wed 04-08-21 12:06:08, Gabriel Krisman Bertazi wrote:
> Plumb the pieces to add a FID report to error records. Since all error
> event memory must be pre-allocated, we estimate a file handler size and
> if it is insuficient, we report an invalid FID and increase the
> prediction for the next error slot allocation.
>
> For errors that don't expose a file handler report it with an invalid
> FID.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
...
> @@ -715,6 +717,31 @@ static void fanotify_insert_error_event(struct fsnotify_group *group,
> fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> fee->error = report->error;
> fee->err_count = 1;
> + fee->fsid = fee->sb_mark->fsn_mark.connector->fsid;
> +
> + /*
> + * Error reporting needs to happen in atomic context. If this
> + * inode's file handler length is more than we initially
> + * predicted, there is nothing better we can do than report the
> + * error with a bad file handler.
> + */
> + fh_len = fanotify_encode_fh_len(inode);
> + if (fh_len > fee->sb_mark->pred_fh_len) {
> + pr_warn_ratelimited(
> + "FH overflows error event. Drop inode information.\n");
> + /*
> + * Update the handler size prediction for the next error
> + * event allocation. This reduces the chance of another
> + * overflow.
> + */
> + fee->sb_mark->pred_fh_len = fh_len;
> +
> + /* For the current error, ignore the inode information. */
> + inode = NULL;
> + fh_len = fanotify_encode_fh_len(NULL);
> + }
> +
> + fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
> }
I don't think calling fanotify_encode_fh() from under notification_lock is
a good practice. It calls into a filesystem and god knows which locks it may
need to take to get necessary info... See my reply to patch 18 how we could
handle that better.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
