From: Ian Kent <raven-PKsaG3nR2I+sTnJN9+BGXg@public.gmane.org> To: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-afs-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: Re: [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() [ver #2] Date: Mon, 26 Jul 2010 23:22:48 +0800 [thread overview] Message-ID: <1280157768.3569.14.camel@localhost> (raw) In-Reply-To: <9168.1280153997-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> On Mon, 2010-07-26 at 15:19 +0100, David Howells wrote: > Ian Kent <raven-PKsaG3nR2I+sTnJN9+BGXg@public.gmane.org> wrote: > > > > (4) Stops pathwalk at the automount point and returns that point in the fs > > > tree if it decides not to automount rather than reporting ELOOP (see its > > > use of EXDEV for this). > > Does it make autofs easier if d_op->d_automount() is allowed to return -EXDEV > to request this? Then you can return it in Oz mode to allow the daemon to > see/use the underlying mountpoint without recursing back into d_automount(). Yes, it's really useful. > > Ideally, the daemon would use AT_NO_AUTOMOUNT, but there's no way to pass that > to sys_mount() or sys_umount(). The use of EXDEV, and if we had a way of saying we want a negative dentry to trigger a mount, allows this mechanism to work for autofs without any user space changes for direct and indirect mounts, at least to match the current function. Having said that though I've only just begun to test the various cases. I know this was originally meant to deal with just the follow_link abuse but the approach as it is appears to be able to resolve a long standing deadlock bug autofs has with indirect mounts and affords a huge amount of simplification to the autofs module code. I really hope we can work out a suitable way to change the implementation to allow for negative dentrys to trigger mounts. Of course it's quite possible I'll hit a snag during testing but I hope not as I've spent a lot of time on alternate approaches in the last few years. Ian
WARNING: multiple messages have this Message-ID (diff)
From: Ian Kent <raven@themaw.net> To: David Howells <dhowells@redhat.com> Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() [ver #2] Date: Mon, 26 Jul 2010 23:22:48 +0800 [thread overview] Message-ID: <1280157768.3569.14.camel@localhost> (raw) In-Reply-To: <9168.1280153997@redhat.com> On Mon, 2010-07-26 at 15:19 +0100, David Howells wrote: > Ian Kent <raven@themaw.net> wrote: > > > > (4) Stops pathwalk at the automount point and returns that point in the fs > > > tree if it decides not to automount rather than reporting ELOOP (see its > > > use of EXDEV for this). > > Does it make autofs easier if d_op->d_automount() is allowed to return -EXDEV > to request this? Then you can return it in Oz mode to allow the daemon to > see/use the underlying mountpoint without recursing back into d_automount(). Yes, it's really useful. > > Ideally, the daemon would use AT_NO_AUTOMOUNT, but there's no way to pass that > to sys_mount() or sys_umount(). The use of EXDEV, and if we had a way of saying we want a negative dentry to trigger a mount, allows this mechanism to work for autofs without any user space changes for direct and indirect mounts, at least to match the current function. Having said that though I've only just begun to test the various cases. I know this was originally meant to deal with just the follow_link abuse but the approach as it is appears to be able to resolve a long standing deadlock bug autofs has with indirect mounts and affords a huge amount of simplification to the autofs module code. I really hope we can work out a suitable way to change the implementation to allow for negative dentrys to trigger mounts. Of course it's quite possible I'll hit a snag during testing but I hope not as I've spent a lot of time on alternate approaches in the last few years. Ian
next prev parent reply other threads:[~2010-07-26 15:22 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-07-22 17:58 [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() David Howells 2010-07-22 17:58 ` David Howells 2010-07-22 17:58 ` [PATCH 2/6] AFS: Use d_automount() " David Howells 2010-07-22 17:59 ` [PATCH 5/6] Remove the automount through follow_link() kludge code from pathwalk David Howells 2010-07-22 17:59 ` [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount David Howells [not found] ` <20100722175847.5552.11520.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org> 2010-07-22 17:58 ` [PATCH 3/6] NFS: Use d_automount() rather than abusing follow_link() David Howells 2010-07-22 17:58 ` David Howells 2010-07-22 17:59 ` [PATCH 4/6] CIFS: " David Howells 2010-07-22 17:59 ` David Howells 2010-07-23 15:09 ` [PATCH 1/6] Add a dentry op to handle automounting rather than abusing follow_link() [ver #2] David Howells 2010-07-23 15:09 ` David Howells [not found] ` <17723.1279897759-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2010-07-24 4:11 ` Ian Kent 2010-07-24 4:11 ` Ian Kent 2010-07-26 14:19 ` David Howells [not found] ` <9168.1280153997-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2010-07-26 15:22 ` Ian Kent [this message] 2010-07-26 15:22 ` Ian Kent 2010-07-26 15:54 ` David Howells [not found] ` <30118.1280159695-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2010-07-27 3:43 ` Ian Kent 2010-07-27 3:43 ` Ian Kent 2010-07-27 8:48 ` David Howells [not found] ` <12883.1280220521-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 2010-07-27 12:51 ` Ian Kent 2010-07-27 12:51 ` Ian Kent [not found] ` <20100722175913.5552.3905.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org> 2010-07-22 18:01 ` [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount David Howells 2010-07-22 18:01 ` David Howells 2010-07-23 15:11 ` [PATCH 6/6] Add an AT_NO_AUTOMOUNT flag to suppress terminal automount [ver #2] David Howells 2010-07-23 15:11 ` David Howells 2010-07-23 15:11 ` David Howells
Reply instructions: You may reply publicly 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=1280157768.3569.14.camel@localhost \ --to=raven-pksag3nr2i+stnjn9+bgxg@public.gmane.org \ --cc=dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \ --cc=linux-afs-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org \ --cc=linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \ --cc=linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \ --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \ --cc=linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \ --cc=viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.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: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.