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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Joshua Watt <jpewhacker@gmail.com>
Cc: NeilBrown <neilb@suse.com>, Jeff Layton <jlayton@redhat.com>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	"J . Bruce Fields" <bfields@fieldses.org>,
	linux-nfs@vger.kernel.org, David Howells <dhowells@redhat.com>
Subject: Re: [RFC v4 4/9] namespace: Add umount_end superblock operation
Date: Wed, 6 Dec 2017 12:33:44 +0000	[thread overview]
Message-ID: <20171206123344.GA9875@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20171206121441.GA21978@ZenIV.linux.org.uk>

On Wed, Dec 06, 2017 at 12:14:41PM +0000, Al Viro wrote:
> On Fri, Nov 17, 2017 at 11:45:47AM -0600, Joshua Watt wrote:
> > The umount_end operation allows cleaning of state set by umount_begin in
> > the event the filesystem doesn't actually get unmounted.
> 
> The locking doesn't make any sense.  This thing can come at *any* moment -
> one process does this force-unmount of yours, another comes and accesses
> the damn thing just as you've decided that umount has failed and go
> to call that method.

Consider, BTW, the situation when another umount -f comes just as you've
dropped ->s_umount.  Now your ->umount_end() comes *after* ->umount_begin()
from the second call.

  reply	other threads:[~2017-12-06 12:33 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-17 17:45 [RFC v4 0/9] NFS Force Unmounting Joshua Watt
2017-11-17 17:45 ` [RFC v4 1/9] SUNRPC: Add flag to kill new tasks Joshua Watt
2017-12-05 22:59   ` NeilBrown
2017-11-17 17:45 ` [RFC v4 2/9] SUNRPC: Expose kill_new_tasks in debugfs Joshua Watt
2017-11-17 17:45 ` [RFC v4 3/9] SUNRPC: Simplify client shutdown Joshua Watt
2017-11-17 17:45 ` [RFC v4 4/9] namespace: Add umount_end superblock operation Joshua Watt
2017-12-06 11:54   ` Jeff Layton
2017-12-06 12:14   ` Al Viro
2017-12-06 12:33     ` Al Viro [this message]
2017-12-06 15:41       ` Joshua Watt
2017-11-17 17:45 ` [RFC v4 5/9] NFS: Kill RPCs for the duration of umount Joshua Watt
2017-12-05 23:07   ` NeilBrown
2017-11-17 17:45 ` [RFC v4 6/9] NFS: Add debugfs for nfs_server and nfs_client Joshua Watt
2017-11-17 17:45 ` [RFC v4 7/9] NFS: Add transient mount option Joshua Watt
2017-12-06 12:23   ` Jeff Layton
2017-11-17 17:45 ` [RFC v4 8/9] NFS: Don't shared transient clients Joshua Watt
2017-11-17 17:45 ` [RFC v4 9/9] NFS: Kill all client RPCs if transient Joshua Watt
2017-12-04 14:36 ` [RFC v4 0/9] NFS Force Unmounting Joshua Watt
2017-12-05 23:34   ` NeilBrown
2017-12-06 13:03     ` Jeff Layton
2017-12-06 16:40       ` Joshua Watt
2017-12-08  2:10       ` NeilBrown
2017-12-14 18:22         ` Joshua Watt
2017-12-14 21:52           ` NeilBrown
2017-12-18 21:48             ` Joshua Watt

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