From: Miklos Szeredi <miklos@szeredi.hu> To: Ian Kent <raven@themaw.net> Cc: David Howells <dhowells@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Al Viro <viro@zeniv.linux.org.uk>, Casey Schaufler <casey@schaufler-ca.com>, Stephen Smalley <sds@tycho.nsa.gov>, Nicolas Dichtel <nicolas.dichtel@6wind.com>, Christian Brauner <christian@brauner.io>, andres@anarazel.de, Jeff Layton <jlayton@redhat.com>, dray@redhat.com, Karel Zak <kzak@redhat.com>, keyrings@vger.kernel.org, Linux API <linux-api@vger.kernel.org>, linux-fsdevel@vger.kernel.org, LSM <linux-security-module@vger.kernel.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5] Date: Wed, 05 Aug 2020 07:43:38 +0000 [thread overview] Message-ID: <CAJfpegvxKTy+4Zk6banvxQ83PeFV7Xnt2Qv=kkOg57rxFKqVEg@mail.gmail.com> (raw) In-Reply-To: <c558fc4af785f62a2751be3b297d1ccbbfcfa969.camel@themaw.net> On Wed, Aug 5, 2020 at 3:54 AM Ian Kent <raven@themaw.net> wrote: > > > > It's way more useful to have these in the notification than > > > obtainable > > > via fsinfo() IMHO. > > > > What is it useful for? > > Only to verify that you have seen all the notifications. > > If you have to grab that info with a separate call then the count > isn't necessarily consistent because other notifications can occur > while you grab it. No, no no. The watch queue will signal an overflow, without any additional overhead for the normal case. If you think of this as a protocol stack, then the overflow detection happens on the transport layer, instead of the application layer. The application layer is responsible for restoring state in case of a transport layer error, but detection of that error is not the responsibility of the application layer. Thanks, Miklos
WARNING: multiple messages have this Message-ID (diff)
From: Miklos Szeredi <miklos@szeredi.hu> To: Ian Kent <raven@themaw.net> Cc: David Howells <dhowells@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Al Viro <viro@zeniv.linux.org.uk>, Casey Schaufler <casey@schaufler-ca.com>, Stephen Smalley <sds@tycho.nsa.gov>, Nicolas Dichtel <nicolas.dichtel@6wind.com>, Christian Brauner <christian@brauner.io>, andres@anarazel.de, Jeff Layton <jlayton@redhat.com>, dray@redhat.com, Karel Zak <kzak@redhat.com>, keyrings@vger.kernel.org, Linux API <linux-api@vger.kernel.org>, linux-fsdevel@vger.kernel.org, LSM <linux-security-module@vger.kernel.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications [ver #5] Date: Wed, 5 Aug 2020 09:43:38 +0200 [thread overview] Message-ID: <CAJfpegvxKTy+4Zk6banvxQ83PeFV7Xnt2Qv=kkOg57rxFKqVEg@mail.gmail.com> (raw) In-Reply-To: <c558fc4af785f62a2751be3b297d1ccbbfcfa969.camel@themaw.net> On Wed, Aug 5, 2020 at 3:54 AM Ian Kent <raven@themaw.net> wrote: > > > > It's way more useful to have these in the notification than > > > obtainable > > > via fsinfo() IMHO. > > > > What is it useful for? > > Only to verify that you have seen all the notifications. > > If you have to grab that info with a separate call then the count > isn't necessarily consistent because other notifications can occur > while you grab it. No, no no. The watch queue will signal an overflow, without any additional overhead for the normal case. If you think of this as a protocol stack, then the overflow detection happens on the transport layer, instead of the application layer. The application layer is responsible for restoring state in case of a transport layer error, but detection of that error is not the responsibility of the application layer. Thanks, Miklos
next prev parent reply other threads:[~2020-08-05 7:43 UTC|newest] Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-18 15:03 [PATCH 00/17] pipe: Keyrings, mount and superblock notifications [ver #5] David Howells 2020-03-18 15:03 ` David Howells 2020-03-18 15:03 ` [PATCH 01/17] uapi: General notification queue definitions " David Howells 2020-03-18 15:03 ` [PATCH 02/17] security: Add hooks to rule on setting a watch " David Howells 2020-03-18 15:03 ` David Howells 2020-03-18 18:56 ` James Morris 2020-03-18 18:56 ` James Morris 2020-03-18 15:03 ` [PATCH 03/17] security: Add a hook for the point of notification insertion " David Howells 2020-03-18 15:03 ` David Howells 2020-03-18 18:57 ` James Morris 2020-03-18 18:57 ` James Morris 2020-03-18 15:03 ` [PATCH 04/17] pipe: Add O_NOTIFICATION_PIPE " David Howells 2020-03-18 15:03 ` [PATCH 05/17] pipe: Add general notification queue support " David Howells 2020-03-18 15:03 ` David Howells 2020-03-18 15:04 ` [PATCH 06/17] watch_queue: Add a key/keyring notification facility " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 19:04 ` James Morris 2020-03-18 19:04 ` James Morris 2020-03-18 15:04 ` [PATCH 07/17] Add sample notification program " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 15:04 ` [PATCH 08/17] pipe: Allow buffers to be marked read-whole-or-error for notifications " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 15:04 ` [PATCH 09/17] pipe: Add notification lossage handling " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 15:04 ` [PATCH 10/17] selinux: Implement the watch_key security hook " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 19:06 ` James Morris 2020-03-18 19:06 ` James Morris 2020-03-18 15:04 ` [PATCH 11/17] smack: Implement the watch_key and post_notification hooks " David Howells 2020-03-18 15:04 ` David Howells 2020-03-18 15:05 ` [PATCH 12/17] watch_queue: Add security hooks to rule on setting mount and sb watches " David Howells 2020-03-18 15:05 ` David Howells 2020-03-18 19:07 ` James Morris 2020-03-18 19:07 ` James Morris 2020-03-18 15:05 ` [PATCH 13/17] watch_queue: Implement mount topology and attribute change notifications " David Howells 2020-03-18 15:05 ` David Howells 2020-04-02 15:19 ` Miklos Szeredi 2020-04-02 15:19 ` Miklos Szeredi 2020-06-14 3:07 ` Ian Kent 2020-06-14 3:07 ` Ian Kent 2020-06-15 8:44 ` Miklos Szeredi 2020-06-15 8:44 ` Miklos Szeredi 2020-07-23 10:48 ` David Howells 2020-07-23 10:48 ` David Howells 2020-08-03 9:29 ` Miklos Szeredi 2020-08-03 9:29 ` Miklos Szeredi 2020-08-04 11:38 ` Ian Kent 2020-08-04 11:38 ` Ian Kent 2020-08-04 13:19 ` Miklos Szeredi 2020-08-04 13:19 ` Miklos Szeredi 2020-08-05 1:53 ` Ian Kent 2020-08-05 1:53 ` Ian Kent 2020-08-05 7:43 ` Miklos Szeredi [this message] 2020-08-05 7:43 ` Miklos Szeredi 2020-08-05 11:36 ` Ian Kent 2020-08-05 11:36 ` Ian Kent 2020-08-05 11:56 ` Miklos Szeredi 2020-08-05 11:56 ` Miklos Szeredi 2020-07-24 10:19 ` David Howells 2020-07-24 10:19 ` David Howells 2020-07-24 10:44 ` Ian Kent 2020-07-24 10:44 ` Ian Kent 2020-07-24 11:36 ` David Howells 2020-07-24 11:36 ` David Howells 2020-08-03 10:02 ` Miklos Szeredi 2020-08-03 10:02 ` Miklos Szeredi 2020-08-03 10:08 ` David Howells 2020-08-03 10:08 ` David Howells 2020-08-03 10:18 ` David Howells 2020-08-03 10:18 ` David Howells 2020-08-03 11:17 ` Miklos Szeredi 2020-08-03 11:17 ` Miklos Szeredi 2020-08-03 11:49 ` David Howells 2020-08-03 11:49 ` David Howells 2020-08-03 12:01 ` Ian Kent 2020-08-03 12:01 ` Ian Kent 2020-08-03 12:31 ` David Howells 2020-08-03 12:31 ` David Howells 2020-08-03 14:30 ` Ian Kent 2020-08-03 14:30 ` Ian Kent 2020-03-18 15:05 ` [PATCH 14/17] watch_queue: sample: Display mount tree " David Howells 2020-03-18 15:05 ` David Howells 2020-03-18 15:05 ` [PATCH 15/17] watch_queue: Introduce a non-repeating system-unique superblock ID " David Howells 2020-03-18 15:05 ` [PATCH 16/17] watch_queue: Add superblock notifications " David Howells 2020-03-18 15:05 ` David Howells 2020-03-18 15:05 ` [PATCH 17/17] watch_queue: sample: Display " David Howells 2020-03-18 15:05 ` David Howells
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