[CRIU] [PATCH] proc: show mnt_id in fdinfo files

[Andrey Vagin]

Currently we don't have a way how to determing from which mount point
file has been opened. This information is required for proper dumping
and restoring file descriptos due to presence of mount namespaces. It's
possible, that two file descriptors are opened using the same paths, but
one fd references mount point from one namespace while the other fd --
from other namespace.

Cc: Al Viro <viro at zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg at redhat.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Cyrill Gorcunov <gorcunov at openvz.org>
Cc: Pavel Emelyanov <xemul at parallels.com>
Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 fs/proc/fd.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 985ea88..0788d09 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -11,6 +11,7 @@
 
 #include <linux/proc_fs.h>
 
+#include "../mount.h"
 #include "internal.h"
 #include "fd.h"
 
@@ -48,8 +49,9 @@ static int seq_show(struct seq_file *m, void *v)
 	}
 
 	if (!ret) {
-                seq_printf(m, "pos:\t%lli\nflags:\t0%o\n",
-			   (long long)file->f_pos, f_flags);
+		seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
+			   (long long)file->f_pos, f_flags,
+			   real_mount(file->f_path.mnt)->mnt_id);
 		if (file->f_op->show_fdinfo)
 			ret = file->f_op->show_fdinfo(m, file);
 		fput(file);
-- 
1.8.5.3