Some kernel special fs could be mounted by userspace, let's show userspace mnt_id in those cases.
Otherwise, I got: [~]# cat /proc/11299/fdinfo/3 pos: 0 flags: 02000002 mnt_id: 14 [~]# cat /proc/11299/mountinfo | grep '^14' [~]# ls -l /proc/11299/fd/3 lrwx------. 1 root root 64 Nov 7 18:30 /proc/11299/fd/3 -> /test-queue [~]# ls /dev/mqueue/ test-queue [~]# cat /proc/11299/mountinfo | grep mqueue 32 18 0:14 / /dev/mqueue rw,relatime shared:17 - mqueue mqueue rw,seclabel This happens because mqueue fs is mounted twice: - the first is kernel-internal mnt on init: kernel_init=>do_one_initcall=>init_mqueue_fs=>mq_init_ns=>vfs_kern_mount - the second time it's systemd's mount-unit: entry_SYSCALL_64_fastpath=>SyS_mount=>do_mount=>vfs_kern_mount For the purpose of userspace parsing, having in-kernel mnt_id is less useful then mnt_id of mount point: afterwards I'm able to see fs type, path, etc: [~]# cat /proc/11152/mountinfo | grep mqueue 32 18 0:14 / /dev/mqueue rw,relatime shared:18 - mqueue mqueue rw,seclabel [~]# cat /proc/11152/fdinfo/3 pos: 0 flags: 02000002 mnt_id: 32 On a bad side - if we've no userspace mount, we still can't tell a thing about opened fd.. Cc: Al Viro <[email protected]> Cc: Andrey Vagin <[email protected]> Cc: "Eric W. Biederman" <[email protected]> Cc: Rob Landley <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> --- fs/proc/fd.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/fs/proc/fd.c b/fs/proc/fd.c index d21dafef3102..bfa8699bcd8e 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -9,6 +9,7 @@ #include <linux/file.h> #include <linux/seq_file.h> #include <linux/fs.h> +#include <linux/nsproxy.h> #include <linux/proc_fs.h> @@ -19,9 +20,10 @@ static int seq_show(struct seq_file *m, void *v) { struct files_struct *files = NULL; - int f_flags = 0, ret = -ENOENT; + int f_flags = 0, ret = -ENOENT, mnt_id = 0; struct file *file = NULL; struct task_struct *task; + struct mount *mount; task = get_proc_task(m->private); if (!task) @@ -52,9 +54,25 @@ static int seq_show(struct seq_file *m, void *v) if (ret) return ret; + mount = real_mount(file->f_path.mnt); + if (mount->mnt_ns == MNT_NS_INTERNAL) { + struct mount *mnt; + + lock_mount_hash(); + list_for_each_entry(mnt, &mount->mnt_instance, mnt_instance) { + if (current->nsproxy->mnt_ns == mnt->mnt_ns) { + mnt_id = mnt->mnt_id; + break; + } + } + unlock_mount_hash(); + } + + if (mnt_id == 0) + mnt_id = mount->mnt_id; + 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); + (long long)file->f_pos, f_flags, mnt_id); show_fd_locks(m, file, files); if (seq_has_overflowed(m)) -- 2.10.2
