summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--fs/namespace.c18
-rw-r--r--include/linux/mount.h1
-rw-r--r--ipc/mqueue.c5
-rw-r--r--ipc/namespace.c13
-rw-r--r--ipc/util.h2
5 files changed, 25 insertions, 14 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index ab467ee58341..1ad4e5acef06 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1397,6 +1397,17 @@ struct vfsmount *mntget(struct vfsmount *mnt)
}
EXPORT_SYMBOL(mntget);
+/*
+ * Make a mount point inaccessible to new lookups.
+ * Because there may still be current users, the caller MUST WAIT
+ * for an RCU grace period before destroying the mount point.
+ */
+void mnt_make_shortterm(struct vfsmount *mnt)
+{
+ if (mnt)
+ real_mount(mnt)->mnt_ns = NULL;
+}
+
/**
* path_is_mountpoint() - Check if path is a mount in the current namespace.
* @path: path to check
@@ -4573,8 +4584,8 @@ EXPORT_SYMBOL_GPL(kern_mount);
void kern_unmount(struct vfsmount *mnt)
{
/* release long term mount so mount point can be released */
- if (!IS_ERR_OR_NULL(mnt)) {
- real_mount(mnt)->mnt_ns = NULL;
+ if (!IS_ERR(mnt)) {
+ mnt_make_shortterm(mnt);
synchronize_rcu(); /* yecchhh... */
mntput(mnt);
}
@@ -4586,8 +4597,7 @@ void kern_unmount_array(struct vfsmount *mnt[], unsigned int num)
unsigned int i;
for (i = 0; i < num; i++)
- if (mnt[i])
- real_mount(mnt[i])->mnt_ns = NULL;
+ mnt_make_shortterm(mnt[i]);
synchronize_rcu_expedited();
for (i = 0; i < num; i++)
mntput(mnt[i]);
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 62475996fac6..ec55a031aa8c 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -88,6 +88,7 @@ extern void mnt_drop_write(struct vfsmount *mnt);
extern void mnt_drop_write_file(struct file *file);
extern void mntput(struct vfsmount *mnt);
extern struct vfsmount *mntget(struct vfsmount *mnt);
+extern void mnt_make_shortterm(struct vfsmount *mnt);
extern struct vfsmount *mnt_clone_internal(const struct path *path);
extern bool __mnt_is_readonly(struct vfsmount *mnt);
extern bool mnt_may_suid(struct vfsmount *mnt);
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index d09aa1c1e3e6..6c5bf7cce7fe 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -1709,11 +1709,6 @@ void mq_clear_sbinfo(struct ipc_namespace *ns)
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}
-void mq_put_mnt(struct ipc_namespace *ns)
-{
- kern_unmount(ns->mq_mnt);
-}
-
static int __init init_mqueue_fs(void)
{
int error;
diff --git a/ipc/namespace.c b/ipc/namespace.c
index a26860a41dac..6ecc30effd3e 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -145,10 +145,11 @@ void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
static void free_ipc_ns(struct ipc_namespace *ns)
{
- /* mq_put_mnt() waits for a grace period as kern_unmount()
- * uses synchronize_rcu().
+ /*
+ * Caller needs to wait for an RCU grace period to have passed
+ * after making the mount point inaccessible to new accesses.
*/
- mq_put_mnt(ns);
+ mntput(ns->mq_mnt);
sem_exit_ns(ns);
msg_exit_ns(ns);
shm_exit_ns(ns);
@@ -169,6 +170,12 @@ static void free_ipc(struct work_struct *unused)
struct ipc_namespace *n, *t;
llist_for_each_entry_safe(n, t, node, mnt_llist)
+ mnt_make_shortterm(n->mq_mnt);
+
+ /* Wait for any last users to have gone away. */
+ synchronize_rcu();
+
+ llist_for_each_entry_safe(n, t, node, mnt_llist)
free_ipc_ns(n);
}
diff --git a/ipc/util.h b/ipc/util.h
index b2906e366539..67bdd2aa2c28 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -56,10 +56,8 @@ struct pid_namespace;
#ifdef CONFIG_POSIX_MQUEUE
extern void mq_clear_sbinfo(struct ipc_namespace *ns);
-extern void mq_put_mnt(struct ipc_namespace *ns);
#else
static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
-static inline void mq_put_mnt(struct ipc_namespace *ns) { }
#endif
#ifdef CONFIG_SYSVIPC