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[patch 5/7] vfs: mountinfo: allow using process root 

Allow /proc/<pid>/mountinfo to use the root of <pid> to calculate
mountpoints.

 - move definition of 'struct proc_mounts' to <linux/mnt_namespace.h>
 - add the process's namespace and root to this structure
 - pass a pointer to 'struct proc_mounts' into seq_operations

In addition the following cleanups are made:

 - use a common open function for /proc/<pid>/{mounts,mountstat}
 - surround namespace.c part of these proc files with #ifdef CONFIG_PROC_FS
 - make the seq_operations structures const

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miklos Szeredi 2008-03-27 13:06:24 +01:00 committed by Al Viro
parent 719f5d7f0b
commit a1a2c409b6
3 changed files with 70 additions and 63 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
fs/namespace.c
View File

@ -724,20 +724,21 @@ void save_mount_options(struct super_block *sb, char *options)
}
EXPORT_SYMBOL(save_mount_options);
#ifdef CONFIG_PROC_FS
/* iterator */
static void *m_start(struct seq_file *m, loff_t *pos)
{
struct mnt_namespace *n = m->private;
struct proc_mounts *p = m->private;
down_read(&namespace_sem);
return seq_list_start(&n->list, *pos);
return seq_list_start(&p->ns->list, *pos);
}
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
struct mnt_namespace *n = m->private;
struct proc_mounts *p = m->private;
return seq_list_next(v, &n->list, pos);
return seq_list_next(v, &p->ns->list, pos);
}
static void m_stop(struct seq_file *m, void *v)
@ -794,7 +795,7 @@ static int show_vfsmnt(struct seq_file *m, void *v)
return err;
}
struct seq_operations mounts_op = {
const struct seq_operations mounts_op = {
.start = m_start,
.next = m_next,
.stop = m_stop,
@ -833,12 +834,13 @@ static int show_vfsstat(struct seq_file *m, void *v)
return err;
}
struct seq_operations mountstats_op = {
const struct seq_operations mountstats_op = {
.start = m_start,
.next = m_next,
.stop = m_stop,
.show = show_vfsstat,
};
#endif /* CONFIG_PROC_FS */
/**
* may_umount_tree - check if a mount tree is busy

94
fs/proc/base.c
View File

@ -502,17 +502,14 @@ static const struct inode_operations proc_def_inode_operations = {
.setattr = proc_setattr,
};
extern const struct seq_operations mounts_op;
struct proc_mounts {
struct seq_file m;
int event;
};
static int mounts_open(struct inode *inode, struct file *file)
static int mounts_open_common(struct inode *inode, struct file *file,
const struct seq_operations *op)
{
struct task_struct *task = get_proc_task(inode);
struct nsproxy *nsp;
struct mnt_namespace *ns = NULL;
struct fs_struct *fs = NULL;
struct path root;
struct proc_mounts *p;
int ret = -EINVAL;
@ -525,40 +522,61 @@ static int mounts_open(struct inode *inode, struct file *file)
get_mnt_ns(ns);
}
rcu_read_unlock();
if (ns)
fs = get_fs_struct(task);
put_task_struct(task);
}
if (ns) {
if (!ns)
goto err;
if (!fs)
goto err_put_ns;
read_lock(&fs->lock);
root = fs->root;
path_get(&root);
read_unlock(&fs->lock);
put_fs_struct(fs);
ret = -ENOMEM;
p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
if (p) {
if (!p)
goto err_put_path;
file->private_data = &p->m;
ret = seq_open(file, &mounts_op);
if (!ret) {
p->m.private = ns;
ret = seq_open(file, op);
if (ret)
goto err_free;
p->m.private = p;
p->ns = ns;
p->root = root;
p->event = ns->event;
return 0;
}
err_free:
kfree(p);
}
err_put_path:
path_put(&root);
err_put_ns:
put_mnt_ns(ns);
}
err:
return ret;
}
static int mounts_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
struct mnt_namespace *ns = m->private;
put_mnt_ns(ns);
struct proc_mounts *p = file->private_data;
path_put(&p->root);
put_mnt_ns(p->ns);
return seq_release(inode, file);
}
static unsigned mounts_poll(struct file *file, poll_table *wait)
{
struct proc_mounts *p = file->private_data;
struct mnt_namespace *ns = p->m.private;
struct mnt_namespace *ns = p->ns;
unsigned res = 0;
poll_wait(file, &ns->poll, wait);
@ -573,6 +591,11 @@ static unsigned mounts_poll(struct file *file, poll_table *wait)
return res;
}
static int mounts_open(struct inode *inode, struct file *file)
{
return mounts_open_common(inode, file, &mounts_op);
}
static const struct file_operations proc_mounts_operations = {
.open = mounts_open,
.read = seq_read,
@ -581,38 +604,9 @@ static const struct file_operations proc_mounts_operations = {
.poll = mounts_poll,
};
extern const struct seq_operations mountstats_op;
static int mountstats_open(struct inode *inode, struct file *file)
{
int ret = seq_open(file, &mountstats_op);
if (!ret) {
struct seq_file *m = file->private_data;
struct nsproxy *nsp;
struct mnt_namespace *mnt_ns = NULL;
struct task_struct *task = get_proc_task(inode);
if (task) {
rcu_read_lock();
nsp = task_nsproxy(task);
if (nsp) {
mnt_ns = nsp->mnt_ns;
if (mnt_ns)
get_mnt_ns(mnt_ns);
}
rcu_read_unlock();
put_task_struct(task);
}
if (mnt_ns)
m->private = mnt_ns;
else {
seq_release(inode, file);
ret = -EINVAL;
}
}
return ret;
return mounts_open_common(inode, file, &mountstats_op);
}
static const struct file_operations proc_mountstats_operations = {

11
include/linux/mnt_namespace.h
View File

@ -5,6 +5,7 @@
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/nsproxy.h>
#include <linux/seq_file.h>
struct mnt_namespace {
atomic_t count;
@ -14,6 +15,13 @@ struct mnt_namespace {
int event;
};
struct proc_mounts {
struct seq_file m; /* must be the first element */
struct mnt_namespace *ns;
struct path root;
int event;
};
extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *,
struct fs_struct *);
extern void __put_mnt_ns(struct mnt_namespace *ns);
@ -37,5 +45,8 @@ static inline void get_mnt_ns(struct mnt_namespace *ns)
atomic_inc(&ns->count);
}
extern const struct seq_operations mounts_op;
extern const struct seq_operations mountstats_op;
#endif
#endif