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: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-07-04 16:57:51 -04:00
parent 2763d11912
commit 56cbb429d9
4 changed files with 28 additions and 31 deletions

View File

@ -19,18 +19,12 @@ void pin_remove(struct fs_pin *pin)
spin_unlock_irq(&pin->wait.lock); spin_unlock_irq(&pin->wait.lock);
} }
void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
{
spin_lock(&pin_lock);
if (p)
hlist_add_head(&pin->s_list, p);
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) void pin_insert(struct fs_pin *pin, struct vfsmount *m)
{ {
pin_insert_group(pin, m, &m->mnt_sb->s_pins); spin_lock(&pin_lock);
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_kill(struct fs_pin *p) void pin_kill(struct fs_pin *p)

View File

@ -58,7 +58,10 @@ struct mount {
struct mount *mnt_master; /* slave is on master->mnt_slave_list */ struct mount *mnt_master; /* slave is on master->mnt_slave_list */
struct mnt_namespace *mnt_ns; /* containing namespace */ struct mnt_namespace *mnt_ns; /* containing namespace */
struct mountpoint *mnt_mp; /* where is it mounted */ struct mountpoint *mnt_mp; /* where is it mounted */
struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */ 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 */ struct list_head mnt_umounting; /* list entry for umount propagation */
#ifdef CONFIG_FSNOTIFY #ifdef CONFIG_FSNOTIFY
struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks; struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
@ -68,7 +71,7 @@ struct mount {
int mnt_group_id; /* peer group identifier */ int mnt_group_id; /* peer group identifier */
int mnt_expiry_mark; /* true if marked for expiry */ int mnt_expiry_mark; /* true if marked for expiry */
struct hlist_head mnt_pins; struct hlist_head mnt_pins;
struct fs_pin mnt_umount; struct hlist_head mnt_stuck_children;
} __randomize_layout; } __randomize_layout;
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */ #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

View File

@ -171,13 +171,6 @@ unsigned int mnt_get_count(struct mount *mnt)
#endif #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) static struct mount *alloc_vfsmnt(const char *name)
{ {
struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); 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_LIST_HEAD(&mnt->mnt_slave);
INIT_HLIST_NODE(&mnt->mnt_mp_list); INIT_HLIST_NODE(&mnt->mnt_mp_list);
INIT_LIST_HEAD(&mnt->mnt_umounting); INIT_LIST_HEAD(&mnt->mnt_umounting);
init_fs_pin(&mnt->mnt_umount, drop_mountpoint); INIT_HLIST_HEAD(&mnt->mnt_stuck_children);
} }
return mnt; return mnt;
@ -1087,19 +1080,22 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
static void cleanup_mnt(struct mount *mnt) static void cleanup_mnt(struct mount *mnt)
{ {
struct hlist_node *p;
struct mount *m;
/* /*
* This probably indicates that somebody messed * The warning here probably indicates that somebody messed
* up a mnt_want/drop_write() pair. If this * up a mnt_want/drop_write() pair. If this happens, the
* happens, the filesystem was probably unable * filesystem was probably unable to make r/w->r/o transitions.
* to make r/w->r/o transitions.
*/
/*
* The locking used to deal with mnt_count decrement provides barriers, * The locking used to deal with mnt_count decrement provides barriers,
* so mnt_get_writers() below is safe. * so mnt_get_writers() below is safe.
*/ */
WARN_ON(mnt_get_writers(mnt)); WARN_ON(mnt_get_writers(mnt));
if (unlikely(mnt->mnt_pins.first)) if (unlikely(mnt->mnt_pins.first))
mnt_pin_kill(mnt); 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); fsnotify_vfsmount_delete(&mnt->mnt);
dput(mnt->mnt.mnt_root); dput(mnt->mnt.mnt_root);
deactivate_super(mnt->mnt.mnt_sb); deactivate_super(mnt->mnt.mnt_sb);
@ -1168,6 +1164,7 @@ static void mntput_no_expire(struct mount *mnt)
struct mount *p, *tmp; struct mount *p, *tmp;
list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) {
__put_mountpoint(unhash_mnt(p), &list); __put_mountpoint(unhash_mnt(p), &list);
hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children);
} }
} }
unlock_mount_hash(); unlock_mount_hash();
@ -1360,6 +1357,8 @@ EXPORT_SYMBOL(may_umount);
static void namespace_unlock(void) static void namespace_unlock(void)
{ {
struct hlist_head head; struct hlist_head head;
struct hlist_node *p;
struct mount *m;
LIST_HEAD(list); LIST_HEAD(list);
hlist_move_list(&unmounted, &head); hlist_move_list(&unmounted, &head);
@ -1374,7 +1373,10 @@ static void namespace_unlock(void)
synchronize_rcu_expedited(); 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) 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); disconnect = disconnect_mount(p, how);
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
disconnect ? &unmounted : NULL);
if (mnt_has_parent(p)) { if (mnt_has_parent(p)) {
mnt_add_count(p->mnt_parent, -1); mnt_add_count(p->mnt_parent, -1);
if (!disconnect) { 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); list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts);
} else { } else {
umount_mnt(p); umount_mnt(p);
hlist_add_head(&p->mnt_umount, &unmounted);
} }
} }
change_mnt_propagation(p, MS_PRIVATE); change_mnt_propagation(p, MS_PRIVATE);
@ -1622,8 +1623,8 @@ void __detach_mounts(struct dentry *dentry)
while (!hlist_empty(&mp->m_list)) { while (!hlist_empty(&mp->m_list)) {
mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
if (mnt->mnt.mnt_flags & MNT_UMOUNT) { if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
hlist_add_head(&mnt->mnt_umount.s_list, &unmounted);
umount_mnt(mnt); umount_mnt(mnt);
hlist_add_head(&mnt->mnt_umount, &unmounted);
} }
else umount_tree(mnt, UMOUNT_CONNECTED); else umount_tree(mnt, UMOUNT_CONNECTED);
} }

View File

@ -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_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_insert(struct fs_pin *, struct vfsmount *);
void pin_kill(struct fs_pin *); void pin_kill(struct fs_pin *);