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Commit a1a2c409 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

[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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 719f5d7f

fs/namespace.c

+8 −6
Original line number Diff line number Diff line
@@ -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

fs/proc/base.c

+51 −57
Original line number Diff line number Diff line
@@ -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 = {

include/linux/mnt_namespace.h

+11 −0
Original line number Diff line number Diff line
@@ -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