From: Amir Goldstein <email@example.com> To: Sergey Senozhatsky <firstname.lastname@example.org> Cc: email@example.com Subject: Re: [Ksummit-discuss] [TECH TOPIC] Linux kernel SMB server (CIFSD) Date: Wed, 24 Jul 2019 13:50:57 +0300 Message-ID: <CAOQ4uxhdJDnTiANsC4Cv42A5ooeYaTphtGvZgP9Wvp+LCCh1NA@mail.gmail.com> (raw) In-Reply-To: <20190724080347.GA12744@jagdpanzerIV> On Wed, Jul 24, 2019 at 11:03 AM Sergey Senozhatsky <firstname.lastname@example.org> wrote: > > On (07/24/19 14:52), Sergey Senozhatsky wrote: > > On (05/30/19 01:59), Theodore Ts'o wrote: > > > From: Sergey Senozhatsky <email@example.com> > [..] > > To extend the topic with some discussion points: > > > > - We are facing a rather familiar problem. Basically, SMB2 CHANGE_NOTIFY > >  is something what fsnotify normally does, except that we can't use > > it in cifsd kernel module. I see that NFS guys had  same issues some > > time ago. > > > > So the question is - how to do fs notify style monitoring in a kernel > > module (nfsd, cifsd)? Any chance the kernel can start exporting fsnotify > > symbols? I don't see a problem with exporting those symbols. As a matter of fact, I have a plan to use them also from overlayfs. At the time that Jeff posted his patches, there was no active fsnotify maintainer. Jeff, did you abandon this effort for nfsd? > > I even looked at LSM hooks, because they do what we need - invoke > creat, open, truncate, chmod, chown, unlink, callbacks. But, first, > I do realize that LSM was not meant to be used as some sort of fsnotify > replacement, and, second, LSM symbols are not exported anyway :) > fsnotify could actually be called from LSM hooks, see: https://github.com/amir73il/linux/commits/fsnotify_dirent_perm It may or may not be clear to you, but what you get extra from fsnotify compared to using bare LSM hooks is: - Minimal performance overhead for a non-marked object - Ability to subscribe/unsubscribe to certain events dynamically - Manage multiple subscriber instances (groups), like one per SMB session - Queuing infrastructure for async events if you need it Thanks, Amir.
next prev parent reply index Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-30 5:59 Theodore Ts'o 2019-07-24 5:52 ` Sergey Senozhatsky 2019-07-24 8:03 ` Sergey Senozhatsky 2019-07-24 10:50 ` Amir Goldstein [this message] 2019-07-24 10:55 ` Jeff Layton 2019-07-25 5:00 ` Sergey Senozhatsky 2019-07-30 17:01 ` Jan Kara 2019-07-31 3:09 ` Sergey Senozhatsky 2019-07-30 16:55 ` Jan Kara 2019-07-24 11:28 ` Sergey Senozhatsky 2019-07-24 16:42 ` Al Viro
Reply instructions: You may reply publically to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=CAOQ4uxhdJDnTiANsC4Cv42A5ooeYaTphtGvZgP9Wvp+LCCh1NA@mail.gmail.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Ksummit-Discuss Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/ksummit-discuss/0 ksummit-discuss/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 ksummit-discuss ksummit-discuss/ https://lore.kernel.org/ksummit-discuss \ email@example.com public-inbox-index ksummit-discuss Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.linuxfoundation.lists.ksummit-discuss AGPL code for this site: git clone https://public-inbox.org/public-inbox.git