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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 A8542C48BD3 for ; Wed, 26 Jun 2019 09:53:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74090205F4 for ; Wed, 26 Jun 2019 09:53:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="cUbPSTd2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726157AbfFZJxD (ORCPT ); Wed, 26 Jun 2019 05:53:03 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:46967 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726077AbfFZJxC (ORCPT ); Wed, 26 Jun 2019 05:53:02 -0400 Received: by mail-wr1-f67.google.com with SMTP id n4so1916834wrw.13 for ; Wed, 26 Jun 2019 02:53:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=8pQpjdmJVhQvnmEuktN5/Xz1yU/XdyfuqdJKbPiBj1U=; b=cUbPSTd2QPE9FZLfMSLJLxMmumGg04s7XO/R8f+H5EeDpFBizlLoCUMVTp8IsqX58y PjIJSIZMBWNHiezN+AjDBmBjfAmUV1H1kM5gybcPayPWmxcPMAj/yHQVX/argLTD/Ntr RzOr0GP+v1K6/P4amPBPBJTawkg65GekP1qKF2wTmi2eEX8oUhZMUhMh1898QRf/8kJC ehfRtZOpxXK2thYiIWlrh36zePTorr8qJIatVloOPJAmQyFCwd96F+G4n8uNlFdoAmtl cj3vurXgaP6OxdcJK7+Nbu2mwk7GB/JZBA58kLZCemr7eL8pWcU09ePtNiIOmTccnatw idgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=8pQpjdmJVhQvnmEuktN5/Xz1yU/XdyfuqdJKbPiBj1U=; b=KYUkWXFEYVUwh8Uw5Or68RoAJZMQMfMmrkRcJZT3sbF8LCDhAcq9EI9zjatSZiXvLT 1XYfaZRKbs8poF3p+fXdpB/2D+eSwi6u/rcm2tpQH29kPjxSJWB1bzMHC7Md+7LoOHdb vHL4MIW8H4PkwoYj2LAr2rsrloti2zN33NmepO1kaoJ+sxwCv4BWPiRhDWgoI8r9n5c0 jvb+nyrBhyv/y0TA3vfn6+pJreF8Ia6MlohC851xt1Z66lP+9EXGs4tg0rIqmnLcnFBO T6zzYpTP+JHJcPQcvAFCJVQ6ePVCsecKISx6SL9pcPRH9M1Hkb+qzydxktYXr8bBOYr7 rf2g== X-Gm-Message-State: APjAAAW83LVwEjNhDTNlcS9LztEI8QspotC71Yt3M4KpKioyo7hWjPbi 4qLtQdrZ3+hPjUU9TKuHnpkmeg== X-Google-Smtp-Source: APXvYqzENWhsUAdR+lHaBRja7sDCrNPJyr/EbZI0XX6h6F2zd94X4ldLgurF85/sE2NYe80opHkCuA== X-Received: by 2002:a5d:56c1:: with SMTP id m1mr3130331wrw.26.1561542779770; Wed, 26 Jun 2019 02:52:59 -0700 (PDT) Received: from brauner.io ([212.91.227.56]) by smtp.gmail.com with ESMTPSA id w23sm1766190wmi.45.2019.06.26.02.52.58 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 26 Jun 2019 02:52:59 -0700 (PDT) Date: Wed, 26 Jun 2019 11:52:58 +0200 From: Christian Brauner To: David Howells Cc: viro@zeniv.linux.org.uk, raven@themaw.net, mszeredi@redhat.com, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 09/25] vfs: Add mount notification count [ver #14] Message-ID: <20190626095257.yi5k667gxulztyzz@brauner.io> References: <156138532485.25627.7459410522109581052.stgit@warthog.procyon.org.uk> <156138540611.25627.13279299200070977180.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <156138540611.25627.13279299200070977180.stgit@warthog.procyon.org.uk> User-Agent: NeoMutt/20180716 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jun 24, 2019 at 03:10:06PM +0100, David Howells wrote: > Add a notification count on mount objects so that the user can easily check > to see if a mount has changed its attributes or its children. > > Future patches will: > > (1) Provide this value through fsinfo() attributes. > > (2) Hook into the notify_mount() function to provide a notification > interface for userspace to monitor. Sorry, I might have missed this. Is this based on your notification patchset and thus presupposing that your notification patchset has been merged? (One further question below.) > > Signed-off-by: David Howells > --- > > fs/mount.h | 22 ++++++++++++++++++++++ > fs/namespace.c | 13 +++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/fs/mount.h b/fs/mount.h > index 6250de544760..47795802f78e 100644 > --- a/fs/mount.h > +++ b/fs/mount.h > @@ -70,6 +70,7 @@ struct mount { > struct hlist_head mnt_pins; > struct fs_pin mnt_umount; > struct dentry *mnt_ex_mountpoint; > + atomic_t mnt_notify_counter; /* Number of notifications generated */ > } __randomize_layout; > > #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ > @@ -151,3 +152,24 @@ static inline bool is_anon_ns(struct mnt_namespace *ns) > { > return ns->seq == 0; > } > + > +/* > + * Type of mount topology change notification. > + */ > +enum mount_notification_subtype { > + NOTIFY_MOUNT_NEW_MOUNT = 0, /* New mount added */ > + NOTIFY_MOUNT_UNMOUNT = 1, /* Mount removed manually */ > + NOTIFY_MOUNT_EXPIRY = 2, /* Automount expired */ > + NOTIFY_MOUNT_READONLY = 3, /* Mount R/O state changed */ > + NOTIFY_MOUNT_SETATTR = 4, /* Mount attributes changed */ > + NOTIFY_MOUNT_MOVE_FROM = 5, /* Mount moved from here */ > + NOTIFY_MOUNT_MOVE_TO = 6, /* Mount moved to here (compare op_id) */ > +}; > + > +static inline void notify_mount(struct mount *changed, > + struct mount *aux, > + enum mount_notification_subtype subtype, > + u32 info_flags) > +{ > + atomic_inc(&changed->mnt_notify_counter); > +} > diff --git a/fs/namespace.c b/fs/namespace.c > index a49a7d9ed482..1450faab96b9 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -513,6 +513,8 @@ static int mnt_make_readonly(struct mount *mnt) > smp_wmb(); > mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; > unlock_mount_hash(); > + if (ret == 0) > + notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0x10000); > return ret; > } > > @@ -521,6 +523,7 @@ static int __mnt_unmake_readonly(struct mount *mnt) > lock_mount_hash(); > mnt->mnt.mnt_flags &= ~MNT_READONLY; > unlock_mount_hash(); > + notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0); > return 0; > } > > @@ -833,6 +836,7 @@ static void umount_mnt(struct mount *mnt) > { > /* old mountpoint will be dropped when we can do that */ > mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint; > + notify_mount(mnt->mnt_parent, mnt, NOTIFY_MOUNT_UNMOUNT, 0); > unhash_mnt(mnt); > } > > @@ -1472,6 +1476,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) > p = list_first_entry(&tmp_list, struct mount, mnt_list); > list_del_init(&p->mnt_expire); > list_del_init(&p->mnt_list); > + > ns = p->mnt_ns; > if (ns) { > ns->mounts--; > @@ -2095,7 +2100,10 @@ static int attach_recursive_mnt(struct mount *source_mnt, > lock_mount_hash(); > } > if (parent_path) { > + notify_mount(source_mnt->mnt_parent, source_mnt, > + NOTIFY_MOUNT_MOVE_FROM, 0); > detach_mnt(source_mnt, parent_path); > + notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_MOVE_TO, 0); > attach_mnt(source_mnt, dest_mnt, dest_mp); > touch_mnt_namespace(source_mnt->mnt_ns); > } else { > @@ -2104,6 +2112,9 @@ static int attach_recursive_mnt(struct mount *source_mnt, > list_del_init(&source_mnt->mnt_ns->list); > } > mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); > + notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_NEW_MOUNT, > + source_mnt->mnt.mnt_sb->s_flags & SB_SUBMOUNT ? > + 0x10000 : 0); What's that magic 0x10000 mean? > commit_tree(source_mnt); > } > > @@ -2480,6 +2491,7 @@ static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) > mnt->mnt.mnt_flags = mnt_flags; > touch_mnt_namespace(mnt->mnt_ns); > unlock_mount_hash(); > + notify_mount(mnt, NULL, NOTIFY_MOUNT_SETATTR, 0); > } > > /* > @@ -2880,6 +2892,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) > if (!xchg(&mnt->mnt_expiry_mark, 1) || > propagate_mount_busy(mnt, 1)) > continue; > + notify_mount(mnt, NULL, NOTIFY_MOUNT_EXPIRY, 0); > list_move(&mnt->mnt_expire, &graveyard); > } > while (!list_empty(&graveyard)) { >