Commit b2dba1af authored by Al Viro's avatar Al Viro
Browse files

vfs: new internal helper: mnt_has_parent(mnt) 



vfsmounts have ->mnt_parent pointing either to a different vfsmount
or to itself; it's never NULL and termination condition in loops
traversing the tree towards root is mnt == mnt->mnt_parent.  At least
one place (see the next patch) is confused about what's going on;
let's add an explicit helper checking it right way and use it in
all places where we need it.  Not that there had been too many,
but...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent aa9c0e07

fs/dcache.c

+3 −3
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
#include <linux/prefetch.h>

#include <linux/ratelimit.h>

#include "internal.h"

#include "mount.h"



/*

 * Usage:
@@ -2460,9 +2461,8 @@ static int prepend_path(const struct path *path, 


		if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {

			/* Global root? */

			if (vfsmnt->mnt_parent == vfsmnt) {

			if (!mnt_has_parent(vfsmnt))

				goto global_root;

			}

			dentry = vfsmnt->mnt_mountpoint;

			vfsmnt = vfsmnt->mnt_parent;

			continue;
@@ -2862,7 +2862,7 @@ int path_is_under(struct path *path1, struct path *path2) 
	br_read_lock(vfsmount_lock);

	if (mnt != path2->mnt) {

		for (;;) {

			if (mnt->mnt_parent == mnt) {

			if (!mnt_has_parent(mnt)) {

				br_read_unlock(vfsmount_lock);

				return 0;

			}

fs/mount.h

0 → 100644
+6 −0
Original line number Diff line number Diff line 
#include <linux/mount.h>



static inline int mnt_has_parent(struct vfsmount *mnt)

{

	return mnt != mnt->mnt_parent;

}

fs/namespace.c

+7 −7
Original line number Diff line number Diff line
@@ -1182,7 +1182,7 @@ void release_mounts(struct list_head *head) 
	while (!list_empty(head)) {

		mnt = list_first_entry(head, struct vfsmount, mnt_hash);

		list_del_init(&mnt->mnt_hash);

		if (mnt->mnt_parent != mnt) {

		if (mnt_has_parent(mnt)) {

			struct dentry *dentry;

			struct vfsmount *m;
@@ -1222,7 +1222,7 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 
		p->mnt_ns = NULL;

		__mnt_make_shortterm(p);

		list_del_init(&p->mnt_child);

		if (p->mnt_parent != p) {

		if (mnt_has_parent(p)) {

			p->mnt_parent->mnt_ghosts++;

			dentry_reset_mounted(p->mnt_parent, p->mnt_mountpoint);

		}
@@ -1867,7 +1867,7 @@ static int do_move_mount(struct path *path, char *old_name) 
	if (old_path.dentry != old_path.mnt->mnt_root)

		goto out1;



	if (old_path.mnt == old_path.mnt->mnt_parent)

	if (!mnt_has_parent(old_path.mnt))

		goto out1;



	if (S_ISDIR(path->dentry->d_inode->i_mode) !=
@@ -1887,7 +1887,7 @@ static int do_move_mount(struct path *path, char *old_name) 
	    tree_contains_unbindable(old_path.mnt))

		goto out1;

	err = -ELOOP;

	for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent)

	for (p = path->mnt; mnt_has_parent(p); p = p->mnt_parent)

		if (p == old_path.mnt)

			goto out1;
@@ -2604,17 +2604,17 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	error = -EINVAL;

	if (root.mnt->mnt_root != root.dentry)

		goto out4; /* not a mountpoint */

	if (root.mnt->mnt_parent == root.mnt)

	if (!mnt_has_parent(root.mnt))

		goto out4; /* not attached */

	if (new.mnt->mnt_root != new.dentry)

		goto out4; /* not a mountpoint */

	if (new.mnt->mnt_parent == new.mnt)

	if (!mnt_has_parent(new.mnt))

		goto out4; /* not attached */

	/* make sure we can reach put_old from new_root */

	tmp = old.mnt;

	if (tmp != new.mnt) {

		for (;;) {

			if (tmp->mnt_parent == tmp)

			if (!mnt_has_parent(tmp))

				goto out4; /* already mounted on put_old */

			if (tmp->mnt_parent == new.mnt)

				break;

fs/pnode.c

+1 −1
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ static inline struct vfsmount *next_slave(struct vfsmount *p) 
static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry,

			 const struct path *root)

{

	while (mnt != root->mnt && mnt->mnt_parent != mnt) {

	while (mnt != root->mnt && mnt_has_parent(mnt)) {

		dentry = mnt->mnt_mountpoint;

		mnt = mnt->mnt_parent;

	}

fs/pnode.h

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ 
#define _LINUX_PNODE_H



#include <linux/list.h>

#include <linux/mount.h>

#include "mount.h"



#define IS_MNT_SHARED(mnt) (mnt->mnt_flags & MNT_SHARED)

#define IS_MNT_SLAVE(mnt) (mnt->mnt_master)

CRA Git | Maintained and supported by SUSTech CRA and CCSE