Unverified Commit 1fa08aec authored by Christian Brauner's avatar Christian Brauner
Browse files

nsfs: convert to path_from_stashed() helper 

Use the newly added path_from_stashed() helper for nsfs.

Link: https://lore.kernel.org/r/20240218-neufahrzeuge-brauhaus-fb0eb6459771@brauner


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 07fd7c32

fs/nsfs.c

+18 −55
Original line number Diff line number Diff line
@@ -27,7 +27,8 @@ static const struct file_operations ns_file_operations = { 
static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)

{

	struct inode *inode = d_inode(dentry);

	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;

	struct ns_common *ns = inode->i_private;

	const struct proc_ns_operations *ns_ops = ns->ops;



	return dynamic_dname(buffer, buflen, "%s:[%lu]",

		ns_ops->name, inode->i_ino);
@@ -38,7 +39,7 @@ static void ns_prune_dentry(struct dentry *dentry) 
	struct inode *inode = d_inode(dentry);

	if (inode) {

		struct ns_common *ns = inode->i_private;

		atomic_long_set(&ns->stashed, 0);

		WRITE_ONCE(ns->stashed, NULL);

	}

}
@@ -56,54 +57,6 @@ static void nsfs_evict(struct inode *inode) 
	ns->ops->put(ns);

}



static int __ns_get_path(struct path *path, struct ns_common *ns)

{

	struct vfsmount *mnt = nsfs_mnt;

	struct dentry *dentry;

	struct inode *inode;

	unsigned long d;



	rcu_read_lock();

	d = atomic_long_read(&ns->stashed);

	if (!d)

		goto slow;

	dentry = (struct dentry *)d;

	if (!lockref_get_not_dead(&dentry->d_lockref))

		goto slow;

	rcu_read_unlock();

	ns->ops->put(ns);

got_it:

	path->mnt = mntget(mnt);

	path->dentry = dentry;

	return 0;

slow:

	rcu_read_unlock();

	inode = new_inode_pseudo(mnt->mnt_sb);

	if (!inode) {

		ns->ops->put(ns);

		return -ENOMEM;

	}

	inode->i_ino = ns->inum;

	simple_inode_init_ts(inode);

	inode->i_flags |= S_IMMUTABLE;

	inode->i_mode = S_IFREG | S_IRUGO;

	inode->i_fop = &ns_file_operations;

	inode->i_private = ns;



	dentry = d_make_root(inode);	/* not the normal use, but... */

	if (!dentry)

		return -ENOMEM;

	dentry->d_fsdata = (void *)ns->ops;

	d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);

	if (d) {

		d_delete(dentry);	/* make sure ->d_prune() does nothing */

		dput(dentry);

		cpu_relax();

		return -EAGAIN;

	}

	goto got_it;

}



int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,

		     void *private_data)

{
@@ -113,10 +66,16 @@ int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb, 
		struct ns_common *ns = ns_get_cb(private_data);

		if (!ns)

			return -ENOENT;

		ret = __ns_get_path(path, ns);

		ret = path_from_stashed(&ns->stashed, ns->inum, nsfs_mnt,

					&ns_file_operations, ns, path);

		if (ret <= 0 && ret != -EAGAIN)

			ns->ops->put(ns);

	} while (ret == -EAGAIN);



	if (ret < 0)

		return ret;



	return 0;

}



struct ns_get_path_task_args {
@@ -163,10 +122,13 @@ int open_related_ns(struct ns_common *ns, 
			return PTR_ERR(relative);

		}



		err = __ns_get_path(&path, relative);

		err = path_from_stashed(&relative->stashed, relative->inum, nsfs_mnt,

					&ns_file_operations, relative, &path);

		if (err <= 0 && err != -EAGAIN)

			relative->ops->put(relative);

	} while (err == -EAGAIN);



	if (err) {

	if (err < 0) {

		put_unused_fd(fd);

		return err;

	}
@@ -249,7 +211,8 @@ bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino) 
static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)

{

	struct inode *inode = d_inode(dentry);

	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;

	const struct ns_common *ns = inode->i_private;

	const struct proc_ns_operations *ns_ops = ns->ops;



	seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);

	return 0;

include/linux/ns_common.h

+1 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ 
struct proc_ns_operations;



struct ns_common {

	atomic_long_t stashed;

	struct dentry *stashed;

	const struct proc_ns_operations *ops;

	unsigned int inum;

	refcount_t count;

include/linux/proc_ns.h

+1 −1
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ static inline void proc_free_inum(unsigned int inum) {} 


static inline int ns_alloc_inum(struct ns_common *ns)

{

	atomic_long_set(&ns->stashed, 0);

	WRITE_ONCE(ns->stashed, NULL);

	return proc_alloc_inum(&ns->inum);

}