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SubjectRe: [patch 3/3] vfs: fix sys_getcwd for detached mounts
From
Date
> From: Miklos Szeredi <mszeredi@suse.cz>
>
> Currently getcwd(2) on a detached mount will give a garbled result:
>
> > mkdir /mnt/foo
> > mount --bind /etc /mnt/foo
> > cd /mnt/foo/skel
> > /bin/pwd
> /mnt/foo/skel
> > umount -l /mnt/foo
> > /bin/pwd
> etcskel
>
> After the patch it will give "detached:skel" as result.
>
> Thanks to John Johansen for pointing out this bug.
>
> Comment from Al Viro: use "detached:" prefix to differentiate it from
> attached paths.
>
> Reported-by: John Johansen <jjohansen@suse.de>
> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
> ---
> fs/dcache.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/fs/dcache.c
> ===================================================================
> --- linux-2.6.orig/fs/dcache.c 2008-06-23 17:35:39.000000000 +0200
> +++ linux-2.6/fs/dcache.c 2008-06-23 17:46:05.000000000 +0200
> @@ -1828,8 +1828,16 @@ char *__d_path(const struct path *path,
>
> global_root:
> retval += 1; /* hit the slash */
> - if (prepend_name(&retval, &buflen, &dentry->d_name) != 0)
> - goto Elong;
> +
> + if (IS_ROOT(dentry)) {
> + /* Attached, or pseudo filesystem with "foo:" prefix */
> + if (prepend_name(&retval, &buflen, &dentry->d_name) != 0)
> + goto Elong;
> + } else {
> + /* Detached */
> + if (prepend(&retval, &buflen, "detached:", 9) != 0)
> + goto Elong;
> + }
> root->mnt = vfsmnt;
> root->dentry = dentry;
> return retval;
>
> --
>

Darn, this is wrong. It should be looking at vfsmnt->mnt_namespace ==
NULL.

Fixed patch coming up.

Miklos


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