From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD9D0C34050 for ; Wed, 19 Feb 2020 11:23:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FF6221D56 for ; Wed, 19 Feb 2020 11:23:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Q6SaYbVM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726636AbgBSLXC (ORCPT ); Wed, 19 Feb 2020 06:23:02 -0500 Received: from mail-io1-f65.google.com ([209.85.166.65]:39068 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726497AbgBSLXB (ORCPT ); Wed, 19 Feb 2020 06:23:01 -0500 Received: by mail-io1-f65.google.com with SMTP id c16so138991ioh.6; Wed, 19 Feb 2020 03:23:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5L5sWTTrZ8wRnU/gy8xHm/c059safDgzJAFGus5OBsE=; b=Q6SaYbVMYY3YOLYKvGdY1N8Mn5Anz+kGLhlnE74xemF53LIVpuKoJYBML9BgbWjHtn 7NPk32U7yNgoIwHPpe7s9CW7f3wmip3zqmdtFoJ5OipmQWRJcwRNtPxIFfg7el/3wBNz xSA+5EpKtHxsh42FwuKMc7pijGewjyAz3trqTnJUjE8Kk3LAzwIRMcqQLftTdy0cLMYD yEtjtUEpHhEku6BJe+CyBzQy1tE+REOVicmM80tTNhcHelF6ZYtpdcC4WitKOkmm0c4B qR4e62iFdarqOp2S3fbBWXhDGdvPq1PWJXHBXe0krAlqIJGSXViVXBLy/VIdMW9YDaX8 VT2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5L5sWTTrZ8wRnU/gy8xHm/c059safDgzJAFGus5OBsE=; b=U3xbjFPLkhba3hc6GHdaybjnMJBB0TnU/epmwNNp+/LLa92agRd6LXByunxrcqqKA+ J/70TdisZyUP6p4AnprVnE6NzqUt/9jPFo/mC8+P8fp2OMvXW1WXsGR8VL4IFwNFt0E9 TigkFuPF+zeuCaa8+VOkytcrd2BB6gz0P3ikP+z+vXzDWI02XEf5cVIUmSJ74UiqyqiY aupCFs9y/9dA5KQGPsBFNFTzmJ3wVIklcggKShr4Gk/+66j4E9OhaKFMFw94soXMz5fF 5NWwJ/k7RVtmLWfL9YAEoZ0b+2LsbDeuuwUWDd2QJoAa0OZN7VNvtN4+A2B5wYne2DXn HxqA== X-Gm-Message-State: APjAAAX8XhE9TaaJUqtfslYIkMOPqvjGYDn6ysFQomRfnXW7A/KfGi7t HInijoZd5Pmltebalso7RNb/ATk9T2U/uAS040Umgg== X-Google-Smtp-Source: APXvYqxNt6ItIaOSBpi7Y6ue/GG+pGKTBHlsENpdVXtm1U0ZAg5utV/ehJqXRybLxRv+RCGmTU523pHQIpMzEPiGvEU= X-Received: by 2002:a02:8817:: with SMTP id r23mr20735647jai.120.1582111380779; Wed, 19 Feb 2020 03:23:00 -0800 (PST) MIME-Version: 1.0 References: <20200217131455.31107-1-amir73il@gmail.com> <20200217131455.31107-14-amir73il@gmail.com> In-Reply-To: <20200217131455.31107-14-amir73il@gmail.com> From: Amir Goldstein Date: Wed, 19 Feb 2020 13:22:49 +0200 Message-ID: Subject: Re: [PATCH v2 13/16] fanotify: report name info for FAN_DIR_MODIFY event To: Jan Kara Cc: linux-fsdevel , Linux API Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Feb 17, 2020 at 3:15 PM Amir Goldstein wrote: > > Report event FAN_DIR_MODIFY with name in a variable length record similar > to how fid's are reported. With name info reporting implemented, setting > FAN_DIR_MODIFY in mark mask is now allowed. > > When events are reported with name, the reported fid identifies the > directory and the name follows the fid. The info record type for this > event info is FAN_EVENT_INFO_TYPE_DFID_NAME. > > For now, all reported events have at most one info record which is > either FAN_EVENT_INFO_TYPE_FID or FAN_EVENT_INFO_TYPE_DFID_NAME (for > FAN_DIR_MODIFY). Later on, events "on child" will report both records. > > There are several ways that an application can use this information: > > 1. When watching a single directory, the name is always relative to > the watched directory, so application need to fstatat(2) the name > relative to the watched directory. > > 2. When watching a set of directories, the application could keep a map > of dirfd for all watched directories and hash the map by fid obtained > with name_to_handle_at(2). When getting a name event, the fid in the > event info could be used to lookup the base dirfd in the map and then > call fstatat(2) with that dirfd. > > 3. When watching a filesystem (FAN_MARK_FILESYSTEM) or a large set of > directories, the application could use open_by_handle_at(2) with the fid > in event info to obtain dirfd for the directory where event happened and > call fstatat(2) with this dirfd. > > The last option scales better for a large number of watched directories. > The first two options may be available in the future also for non > privileged fanotify watchers, because open_by_handle_at(2) requires > the CAP_DAC_READ_SEARCH capability. > > Signed-off-by: Amir Goldstein > --- > fs/notify/fanotify/fanotify.c | 2 +- > fs/notify/fanotify/fanotify_user.c | 120 ++++++++++++++++++++++------- > include/linux/fanotify.h | 3 +- > include/uapi/linux/fanotify.h | 1 + > 4 files changed, 98 insertions(+), 28 deletions(-) > > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c > index fc75dc53a218..b651c18d3a93 100644 > --- a/fs/notify/fanotify/fanotify.c > +++ b/fs/notify/fanotify/fanotify.c > @@ -478,7 +478,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, > BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC); > BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM); > > - BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19); > + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20); > > mask = fanotify_group_event_mask(group, iter_info, mask, data, > data_type); > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c > index 284f3548bb79..a1bafc21ebbb 100644 > --- a/fs/notify/fanotify/fanotify_user.c > +++ b/fs/notify/fanotify/fanotify_user.c > @@ -51,20 +51,32 @@ struct kmem_cache *fanotify_name_event_cachep __read_mostly; > struct kmem_cache *fanotify_perm_event_cachep __read_mostly; > > #define FANOTIFY_EVENT_ALIGN 4 > +#define FANOTIFY_INFO_HDR_LEN \ > + (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) > > -static int fanotify_fid_info_len(struct fanotify_fid_hdr *fh) > +static int fanotify_fid_info_len(int fh_len, int name_len) > { > - return roundup(sizeof(struct fanotify_event_info_fid) + > - sizeof(struct file_handle) + fh->len, > - FANOTIFY_EVENT_ALIGN); > + int info_len = fh_len; > + > + if (name_len) > + info_len += name_len + 1; > + > + return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN); > } > > static int fanotify_event_info_len(struct fanotify_event *event) > { > - if (!fanotify_event_has_fid(event)) > - return 0; > + int info_len = 0; > + > + if (fanotify_event_has_fid(event)) > + info_len += fanotify_fid_info_len(event->fh.len, 0); > + > + if (fanotify_event_has_dfid_name(event)) { > + info_len += fanotify_fid_info_len(event->dfh.len, > + fanotify_event_name_len(event)); > + } > > - return fanotify_fid_info_len(&event->fh); > + return info_len; > } > > /* > @@ -210,23 +222,34 @@ static int process_access_response(struct fsnotify_group *group, > return -ENOENT; > } > > -static int copy_fid_to_user(__kernel_fsid_t *fsid, struct fanotify_fid_hdr *fh, > - struct fanotify_fid *fid, char __user *buf) > +static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fid_hdr *fh, > + struct fanotify_fid *fid, const struct qstr *name, > + char __user *buf, size_t count) > { > struct fanotify_event_info_fid info = { }; > struct file_handle handle = { }; > - unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *data; > + unsigned char bounce[max(FANOTIFY_INLINE_FH_LEN, DNAME_INLINE_LEN)]; > + const unsigned char *data; > size_t fh_len = fh->len; > - size_t len = fanotify_fid_info_len(fh); > + size_t name_len = name ? name->len : 0; > + size_t info_len = fanotify_fid_info_len(fh_len, name_len); > + size_t len = info_len; > + > + pr_debug("%s: fh_len=%lu name_len=%lu, info_len=%lu, count=%lu\n", > + __func__, fh_len, name_len, info_len, count); > Changed all %lu above to %zu to print size_t without a warning. Thanks kbuild test robot, Amir.