[CRIU] [PATCH] mnt: Use ns_mountpoint to open a mount point

[Andrew Vagin]

On Mon, Oct 12, 2015 at 12:56:55PM +0300, Pavel Emelyanov wrote:
> On 10/09/2015 06:59 PM, Cyrill Gorcunov wrote:
> > From: Andrew Vagin <avagin at openvz.org>
> > 
> > open_mountpoint helper is called when mount namespace are
> > already restored so we have to use local paths.
> 
> 2 questions from my side:
> 
> 1. How is this connected with the patch "fsnotify: save mnt_id with path"?
> 2. Is the test from that set catches this bug?

Yes, it is. I wrote the test to check this patch, but unfortunately
it found one more bug.

> 
> -- Pavel
> 
> > https://jira.sw.ru/browse/PSBM-39957
> > 
> > Signed-off-by: Andrew Vagin <avagin at openvz.org>
> > Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> > ---
> >  fsnotify.c   |  4 ++--
> >  mount.c      | 10 +++++-----
> >  proc_parse.c |  1 +
> >  3 files changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/fsnotify.c b/fsnotify.c
> > index 0d9ec58446b1..3a81a528d7c5 100644
> > --- a/fsnotify.c
> > +++ b/fsnotify.c
> > @@ -526,9 +526,9 @@ static int restore_one_fanotify(int fd, struct fsnotify_mark_info *mark)
> >  
> >  		mntns_root = mntns_get_root_fd(m->nsid);
> >  
> > -		target = openat(mntns_root, m->mountpoint, O_PATH);
> > +		target = openat(mntns_root, m->ns_mountpoint, O_PATH);
> >  		if (target == -1) {
> > -			pr_perror("Unable to open %s", m->mountpoint);
> > +			pr_perror("Unable to open %s", m->ns_mountpoint);
> >  			goto err;
> >  		}
> >  
> > diff --git a/mount.c b/mount.c
> > index 2ed061592f86..8936eda59db5 100644
> > --- a/mount.c
> > +++ b/mount.c
> > @@ -1017,23 +1017,23 @@ static int __open_mountpoint(struct mount_info *pm, int mnt_fd)
> >  		if (mntns_root < 0)
> >  			return -1;
> >  
> > -		mnt_fd = openat(mntns_root, pm->mountpoint, O_RDONLY);
> > +		mnt_fd = openat(mntns_root, pm->ns_mountpoint, O_RDONLY);
> >  		if (mnt_fd < 0) {
> > -			pr_perror("Can't open %s", pm->mountpoint);
> > +			pr_perror("Can't open %s", pm->ns_mountpoint);
> >  			return -1;
> >  		}
> >  	}
> >  
> >  	ret = fstat(mnt_fd, &st);
> >  	if (ret < 0) {
> > -		pr_perror("fstat(%s) failed", pm->mountpoint);
> > +		pr_perror("fstat(%s) failed", pm->ns_mountpoint);
> >  		goto err;
> >  	}
> >  
> > -	dev = phys_stat_resolve_dev(pm->nsid, st.st_dev, pm->mountpoint + 1);
> > +	dev = phys_stat_resolve_dev(pm->nsid, st.st_dev, pm->ns_mountpoint + 1);
> >  	if (dev != pm->s_dev) {
> >  		pr_err("The file system %#x (%#x) %s %s is inaccessible\n",
> > -				pm->s_dev, (int)dev, pm->fstype->name, pm->mountpoint);
> > +		       pm->s_dev, (int)dev, pm->fstype->name, pm->ns_mountpoint);
> >  		goto err;
> >  	}
> >  
> > diff --git a/proc_parse.c b/proc_parse.c
> > index 965c7cbc47c0..7cc6b61a93f4 100644
> > --- a/proc_parse.c
> > +++ b/proc_parse.c
> > @@ -1026,6 +1026,7 @@ static int parse_mountinfo_ent(char *str, struct mount_info *new, char **fsname)
> >  	new->mountpoint = xmalloc(PATH_MAX);
> >  	if (new->mountpoint == NULL)
> >  		goto err;
> > +	new->ns_mountpoint = new->mountpoint;
> >  
> >  	new->mountpoint[0] = '.';
> >  	ret = sscanf(str, "%i %i %u:%u %ms %s %ms %n",
> > 
>