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Commit 56cbb429 authored by Al Viro's avatar Al Viro
Browse files

switch the remnants of releasing the mountpoint away from fs_pin 



We used to need rather convoluted ordering trickery to guarantee
that dput() of ex-mountpoints happens before the final mntput()
of the same.  Since we don't need that anymore, there's no point
playing with fs_pin for that.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 2763d119

fs/fs_pin.c

+2 −8
Original line number Diff line number Diff line
@@ -19,20 +19,14 @@ void pin_remove(struct fs_pin *pin) 
	spin_unlock_irq(&pin->wait.lock);

}



void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)

void pin_insert(struct fs_pin *pin, struct vfsmount *m)

{

	spin_lock(&pin_lock);

	if (p)

		hlist_add_head(&pin->s_list, p);

	hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);

	hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);

	spin_unlock(&pin_lock);

}



void pin_insert(struct fs_pin *pin, struct vfsmount *m)

{

	pin_insert_group(pin, m, &m->mnt_sb->s_pins);

}



void pin_kill(struct fs_pin *p)

{

	wait_queue_entry_t wait;

fs/mount.h

+5 −2
Original line number Diff line number Diff line
@@ -58,7 +58,10 @@ struct mount { 
	struct mount *mnt_master;	/* slave is on master->mnt_slave_list */

	struct mnt_namespace *mnt_ns;	/* containing namespace */

	struct mountpoint *mnt_mp;	/* where is it mounted */

	union {

		struct hlist_node mnt_mp_list;	/* list mounts with the same mountpoint */

		struct hlist_node mnt_umount;

	};

	struct list_head mnt_umounting; /* list entry for umount propagation */

#ifdef CONFIG_FSNOTIFY

	struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
@@ -68,7 +71,7 @@ struct mount { 
	int mnt_group_id;		/* peer group identifier */

	int mnt_expiry_mark;		/* true if marked for expiry */

	struct hlist_head mnt_pins;

	struct fs_pin mnt_umount;

	struct hlist_head mnt_stuck_children;

} __randomize_layout;



#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

fs/namespace.c

+19 −18
Original line number Diff line number Diff line
@@ -171,13 +171,6 @@ unsigned int mnt_get_count(struct mount *mnt) 
#endif

}



static void drop_mountpoint(struct fs_pin *p)

{

	struct mount *m = container_of(p, struct mount, mnt_umount);

	pin_remove(p);

	mntput(&m->mnt);

}



static struct mount *alloc_vfsmnt(const char *name)

{

	struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
@@ -215,7 +208,7 @@ static struct mount *alloc_vfsmnt(const char *name) 
		INIT_LIST_HEAD(&mnt->mnt_slave);

		INIT_HLIST_NODE(&mnt->mnt_mp_list);

		INIT_LIST_HEAD(&mnt->mnt_umounting);

		init_fs_pin(&mnt->mnt_umount, drop_mountpoint);

		INIT_HLIST_HEAD(&mnt->mnt_stuck_children);

	}

	return mnt;
@@ -1087,19 +1080,22 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, 


static void cleanup_mnt(struct mount *mnt)

{

	struct hlist_node *p;

	struct mount *m;

	/*

	 * This probably indicates that somebody messed

	 * up a mnt_want/drop_write() pair.  If this

	 * happens, the filesystem was probably unable

	 * to make r/w->r/o transitions.

	 */

	/*

	 * The warning here probably indicates that somebody messed

	 * up a mnt_want/drop_write() pair.  If this happens, the

	 * filesystem was probably unable to make r/w->r/o transitions.

	 * The locking used to deal with mnt_count decrement provides barriers,

	 * so mnt_get_writers() below is safe.

	 */

	WARN_ON(mnt_get_writers(mnt));

	if (unlikely(mnt->mnt_pins.first))

		mnt_pin_kill(mnt);

	hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) {

		hlist_del(&m->mnt_umount);

		mntput(&m->mnt);

	}

	fsnotify_vfsmount_delete(&mnt->mnt);

	dput(mnt->mnt.mnt_root);

	deactivate_super(mnt->mnt.mnt_sb);
@@ -1168,6 +1164,7 @@ static void mntput_no_expire(struct mount *mnt) 
		struct mount *p, *tmp;

		list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts,  mnt_child) {

			__put_mountpoint(unhash_mnt(p), &list);

			hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children);

		}

	}

	unlock_mount_hash();
@@ -1360,6 +1357,8 @@ EXPORT_SYMBOL(may_umount); 
static void namespace_unlock(void)

{

	struct hlist_head head;

	struct hlist_node *p;

	struct mount *m;

	LIST_HEAD(list);



	hlist_move_list(&unmounted, &head);
@@ -1374,7 +1373,10 @@ static void namespace_unlock(void) 


	synchronize_rcu_expedited();



	group_pin_kill(&head);

	hlist_for_each_entry_safe(m, p, &head, mnt_umount) {

		hlist_del(&m->mnt_umount);

		mntput(&m->mnt);

	}

}



static inline void namespace_lock(void)
@@ -1461,8 +1463,6 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) 


		disconnect = disconnect_mount(p, how);



		pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,

				 disconnect ? &unmounted : NULL);

		if (mnt_has_parent(p)) {

			mnt_add_count(p->mnt_parent, -1);

			if (!disconnect) {
@@ -1470,6 +1470,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how) 
				list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts);

			} else {

				umount_mnt(p);

				hlist_add_head(&p->mnt_umount, &unmounted);

			}

		}

		change_mnt_propagation(p, MS_PRIVATE);
@@ -1622,8 +1623,8 @@ void __detach_mounts(struct dentry *dentry) 
	while (!hlist_empty(&mp->m_list)) {

		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);

		if (mnt->mnt.mnt_flags & MNT_UMOUNT) {

			hlist_add_head(&mnt->mnt_umount.s_list, &unmounted);

			umount_mnt(mnt);

			hlist_add_head(&mnt->mnt_umount, &unmounted);

		}

		else umount_tree(mnt, UMOUNT_CONNECTED);

	}

include/linux/fs_pin.h

+0 −1
Original line number Diff line number Diff line
@@ -20,6 +20,5 @@ static inline void init_fs_pin(struct fs_pin *p, void (*kill)(struct fs_pin *)) 
}



void pin_remove(struct fs_pin *);

void pin_insert_group(struct fs_pin *, struct vfsmount *, struct hlist_head *);

void pin_insert(struct fs_pin *, struct vfsmount *);

void pin_kill(struct fs_pin *);