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-rw-r--r--fs/mount.h5
-rw-r--r--fs/namespace.c71
2 files changed, 57 insertions, 19 deletions
diff --git a/fs/mount.h b/fs/mount.h
index 6740a62..8f2a14a 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -29,7 +29,10 @@ struct mount {
struct mount *mnt_parent;
struct dentry *mnt_mountpoint;
struct vfsmount mnt;
- struct rcu_head mnt_rcu;
+ union {
+ struct rcu_head mnt_rcu;
+ struct llist_node mnt_llist;
+ };
#ifdef CONFIG_SMP
struct mnt_pcp __percpu *mnt_pcp;
#else
diff --git a/fs/namespace.c b/fs/namespace.c
index ef42d9b..0441343 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -23,6 +23,7 @@
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/bootmem.h>
+#include <linux/task_work.h>
#include "pnode.h"
#include "internal.h"
@@ -957,6 +958,46 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
return ERR_PTR(err);
}
+static void cleanup_mnt(struct mount *mnt)
+{
+ /*
+ * 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 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);
+ fsnotify_vfsmount_delete(&mnt->mnt);
+ dput(mnt->mnt.mnt_root);
+ deactivate_super(mnt->mnt.mnt_sb);
+ mnt_free_id(mnt);
+ call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt);
+}
+
+static void __cleanup_mnt(struct rcu_head *head)
+{
+ cleanup_mnt(container_of(head, struct mount, mnt_rcu));
+}
+
+static LLIST_HEAD(delayed_mntput_list);
+static void delayed_mntput(struct work_struct *unused)
+{
+ struct llist_node *node = llist_del_all(&delayed_mntput_list);
+ struct llist_node *next;
+
+ for (; node; node = next) {
+ next = llist_next(node);
+ cleanup_mnt(llist_entry(node, struct mount, mnt_llist));
+ }
+}
+static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
+
static void mntput_no_expire(struct mount *mnt)
{
rcu_read_lock();
@@ -982,24 +1023,18 @@ static void mntput_no_expire(struct mount *mnt)
list_del(&mnt->mnt_instance);
unlock_mount_hash();
- /*
- * 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 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);
- fsnotify_vfsmount_delete(&mnt->mnt);
- dput(mnt->mnt.mnt_root);
- deactivate_super(mnt->mnt.mnt_sb);
- mnt_free_id(mnt);
- call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt);
+ if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) {
+ struct task_struct *task = current;
+ if (likely(!(task->flags & PF_KTHREAD))) {
+ init_task_work(&mnt->mnt_rcu, __cleanup_mnt);
+ if (!task_work_add(task, &mnt->mnt_rcu, true))
+ return;
+ }
+ if (llist_add(&mnt->mnt_llist, &delayed_mntput_list))
+ schedule_delayed_work(&delayed_mntput_work, 1);
+ return;
+ }
+ cleanup_mnt(mnt);
}
void mntput(struct vfsmount *mnt)
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