Re: [PATCH 4/28] VFS: Stat shouldn't stop expire

From: Christoph Hellwig (hch_at_infradead.org)
Date: 10/26/04

  • Next message: Christoph Hellwig: "Re: [PATCH 15/28] VFS: Mountpoint file descriptor umount support" 
    Date:	Tue, 26 Oct 2004 11:27:03 +0100
To: Mike Waychison <michael.waychison@sun.com>

    On Mon, Oct 25, 2004 at 10:40:30AM -0400, Mike Waychison wrote:
    > This patch fixes the problem where if you have a mountpoint that is going to
    > expire, it fails to expire before somebody keeps stat(2)ing the root of it's
    > filesystem. For example, consider the case where a user has his home
    > directory automounted on /home/mikew. Some other user can keep the
    > filesystem mounted forever by simply calling ls(1) in /home, because the stat
    > action resets the marker on each call.
    >
    > Signed-off-by: Mike Waychison <michael.waychison@sun.com>
    > ---
    >
    > namei.c | 11 ++++++++++-
    > 1 files changed, 10 insertions(+), 1 deletion(-)
    >
    > Index: linux-2.6.9-quilt/fs/namei.c
    > ===================================================================
    > --- linux-2.6.9-quilt.orig/fs/namei.c 2004-08-14 01:36:45.000000000 -0400
    > +++ linux-2.6.9-quilt/fs/namei.c 2004-10-22 17:17:34.762179488 -0400
    > @@ -275,7 +275,16 @@ int deny_write_access(struct file * file
    > void path_release(struct nameidata *nd)
    > {
    > dput(nd->dentry);
    > - mntput(nd->mnt);
    > + /*
    > + * In order to ensure that access to an automounted filesystems'
    > + * root does not reset it's expire counter, we check to see if the path
    > + * being released here is a mountpoint itself. If it is, then we call
    > + * _mntput which leaves the expire counter alone.
    > + */
    > + if (nd->mnt && nd->mnt->mnt_root == nd->dentry)
    > + _mntput(nd->mnt);
    > + else
    > + mntput(nd->mnt);

    Why only for the root dentry not any on stat() This seems highly inconsistant.
    Also while you're at it please give _mntput a more sensible name, e.g.
    mntput_no_expire (yes, I know that name isn't your fault)

    -
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  • Next message: Christoph Hellwig: "Re: [PATCH 15/28] VFS: Mountpoint file descriptor umount support"

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