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authorAl Viro <viro@zeniv.linux.org.uk>2019-07-04 16:57:51 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2019-07-16 22:52:37 -0400
commit56cbb429d911991170fe867b4bba14f0efed5829 (patch)
tree0a50d1ccc57136faa844be4e616c9ed7c69322be
parent2763d11912317a12318135ca03e592bb6df65624 (diff)
downloadlinux-56cbb429d911991170fe867b4bba14f0efed5829.tar.bz2
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>
-rw-r--r--fs/fs_pin.c10
-rw-r--r--fs/mount.h7
-rw-r--r--fs/namespace.c37
-rw-r--r--include/linux/fs_pin.h1
4 files changed, 26 insertions, 29 deletions
diff --git a/fs/fs_pin.c b/fs/fs_pin.c
index a6497cf8ae53..47ef3c71ce90 100644
--- a/fs/fs_pin.c
+++ b/fs/fs_pin.c
@@ -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;
diff --git a/fs/mount.h b/fs/mount.h
index 84aa8cdf4971..711a4093e475 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -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 */
- 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 */
#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 */
diff --git a/fs/namespace.c b/fs/namespace.c
index 46316ba15615..54a815e48ead 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -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);
}
diff --git a/include/linux/fs_pin.h b/include/linux/fs_pin.h
index 7cab74d66f85..bdd09fd2520c 100644
--- a/include/linux/fs_pin.h
+++ b/include/linux/fs_pin.h
@@ -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 *);