xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

proc: show mnt_id in /proc/pid/fdinfo

Browse Source 
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.

$ ls -l /proc/1/fd/1
lrwx------ 1 root root 64 Mar 19 23:54 /proc/1/fd/1 -> /dev/null

$ cat /proc/1/fdinfo/1
pos:	0
flags:	0100002
mnt_id:	16

$ cat /proc/1/mountinfo | grep ^16
16 32 0:4 / /dev rw,nosuid shared:2 - devtmpfs devtmpfs rw,size=1013356k,nr_inodes=253339,mode=755

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Rob Landley <rob@landley.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Vagin
2014-04-07 15:38:34 -07:00
committed by Linus Torvalds
parent f0b5664ba7
commit 49d063cb35
2 changed files with 16 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
fs/proc/fd.c
View File

@@ -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);