NFSD: Pin to vfsmount for nfsd exports cache

index 3886b3b..0dde7b7 100644
@@ -1,3 +1,6 @@
+#ifndef _LINUX_FS_PIN_H
+#define _LINUX_FS_PIN_H
+
 #include <linux/wait.h>
 
 struct fs_pin {

@@ -16,9 +19,12 @@ static inline void init_fs_pin(struct fs_pin *p, void (*kill)(struct fs_pin *))
 	INIT_HLIST_NODE(&p->s_list);
 	INIT_HLIST_NODE(&p->m_list);
 	p->kill = kill;
+	p->done = 0;
 }
 
 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 *);
+
+#endif

index 611b540..a1a4eb2 100644
@@ -17,6 +17,7 @@ void pin_remove(struct fs_pin *pin)
 	wake_up_locked(&pin->wait);
 	spin_unlock_irq(&pin->wait.lock);
 }
+EXPORT_SYMBOL(pin_remove);
 
 void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
 {

@@ -26,11 +27,13 @@ void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head
 	hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
 	spin_unlock(&pin_lock);
 }
+EXPORT_SYMBOL(pin_insert_group);
 
 void pin_insert(struct fs_pin *pin, struct vfsmount *m)
 {
 	pin_insert_group(pin, m, &m->mnt_sb->s_pins);
 }
+EXPORT_SYMBOL(pin_insert);
 
 void pin_kill(struct fs_pin *p)
 {

@@ -72,6 +75,7 @@ void pin_kill(struct fs_pin *p)
 	}
 	rcu_read_unlock();
 }
+EXPORT_SYMBOL(pin_kill);
 
 void mnt_pin_kill(struct mount *m)
 {

index 1b9e111..3f08a48 100644
@@ -1049,8 +1049,6 @@ static void cleanup_mnt(struct mount *mnt)
 	 * 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);

@@ -1078,6 +1076,7 @@ static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
 
 static void mntput_no_expire(struct mount *mnt)
 {
+put_again:
 	rcu_read_lock();
 	mnt_add_count(mnt, -1);
 	if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */

@@ -1090,6 +1089,13 @@ static void mntput_no_expire(struct mount *mnt)
 		unlock_mount_hash();
 		return;
 	}
+	if (unlikely(mnt->mnt_pins.first)) {
+		mnt_add_count(mnt, 1);
+		rcu_read_unlock();
+		unlock_mount_hash();
+		mnt_pin_kill(mnt);
+		goto put_again;
+	}
 	if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) {
 		rcu_read_unlock();
 		unlock_mount_hash();

index fe30d3b..8f94e7c 100644
@@ -492,6 +492,32 @@ void path_put(const struct path *path)
 }
 EXPORT_SYMBOL(path_put);
 
+/**
+ * path_get_pin - get a reference to a path's dentry
+ *                and pin to path's vfsmnt
+ * @path: path to get the reference to
+ * @p: the fs_pin pin to vfsmnt
+ */
+void path_get_pin(struct path *path, struct fs_pin *p)
+{
+	dget(path->dentry);
+	pin_insert_group(p, path->mnt, NULL);
+}
+EXPORT_SYMBOL(path_get_pin);
+
+/**
+ * path_put_unpin - put a reference to a path's dentry
+ *                  and remove pin to path's vfsmnt
+ * @path: path to put the reference to
+ * @p: the fs_pin removed from vfsmnt
+ */
+void path_put_unpin(struct path *path, struct fs_pin *p)
+{
+	dput(path->dentry);
+	pin_remove(p);
+}
+EXPORT_SYMBOL(path_put_unpin);
+
 struct nameidata {
 	struct path	path;
 	struct qstr	last;

index d137218..34599fb 100644
@@ -3,6 +3,7 @@
 
 struct dentry;
 struct vfsmount;
+struct fs_pin;
 
 struct path {
 	struct vfsmount *mnt;

@@ -12,6 +13,9 @@ struct path {
 extern void path_get(const struct path *);
 extern void path_put(const struct path *);
 
+extern void path_get_pin(struct path *, struct fs_pin *);
+extern void path_put_unpin(struct path *, struct fs_pin *);
+
 static inline int path_equal(const struct path *path1, const struct path *path2)
 {
 	return path1->mnt == path2->mnt && path1->dentry == path2->dentry;

index 437ddb6..ce75e9c 100644
@@ -210,6 +210,17 @@ extern int cache_check(struct cache_detail *detail,
 		       struct cache_head *h, struct cache_req *rqstp);
 extern void cache_flush(void);
 extern void cache_purge(struct cache_detail *detail);
+
+static inline void cache_force_expire(struct cache_detail *detail, struct cache_head *h)
+{
+	write_lock(&detail->hash_lock);
+	h->expiry_time = seconds_since_boot() - 1;
+	detail->nextcheck = seconds_since_boot();
+	write_unlock(&detail->hash_lock);
+
+	cache_flush();
+}
+
 #define NEVER (0x7FFFFFFF)
 extern void __init cache_initialize(void);
 extern int cache_register_net(struct cache_detail *cd, struct net *net);

index f79521a..d3e59bc 100644
@@ -37,15 +37,23 @@
 #define	EXPKEY_HASHMAX		(1 << EXPKEY_HASHBITS)
 #define	EXPKEY_HASHMASK		(EXPKEY_HASHMAX -1)
 
+static void expkey_destroy(struct svc_expkey *key)
+{
+	auth_domain_put(key->ek_client);
+	kfree_rcu(key, rcu_head);
+}
+
 static void expkey_put(struct kref *ref)
 {
 	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);
 
 	if (test_bit(CACHE_VALID, &key->h.flags) &&
-	    !test_bit(CACHE_NEGATIVE, &key->h.flags))
-		path_put(&key->ek_path);
-	auth_domain_put(key->ek_client);
-	kfree(key);
+	    !test_bit(CACHE_NEGATIVE, &key->h.flags)) {
+		rcu_read_lock();
+		complete(&key->ek_done);
+		pin_kill(&key->ek_pin);
+	} else
+		expkey_destroy(key);
 }
 
 static void expkey_request(struct cache_detail *cd,

@@ -83,7 +91,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
 		return -EINVAL;
 	mesg[mlen-1] = 0;
 
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	err = -ENOMEM;
 	if (!buf)
 		goto out;

@@ -120,6 +128,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
 		goto out;
 
 	key.ek_client = dom;	
+	key.cd = cd;
 	key.ek_fsidtype = fsidtype;
 	memcpy(key.ek_fsid, buf, len);
 

@@ -210,6 +219,25 @@ static inline void expkey_init(struct cache_head *cnew,
 	new->ek_fsidtype = item->ek_fsidtype;
 
 	memcpy(new->ek_fsid, item->ek_fsid, sizeof(new->ek_fsid));
+	new->cd = item->cd;
+}
+
+static void expkey_pin_kill(struct fs_pin *pin)
+{
+	struct svc_expkey *key = container_of(pin, struct svc_expkey, ek_pin);
+
+	if (!completion_done(&key->ek_done)) {
+		schedule_work(&key->ek_work);
+		wait_for_completion(&key->ek_done);
+	}
+	path_put_unpin(&key->ek_path, &key->ek_pin);
+	expkey_destroy(key);
+}
+
+static void expkey_close_work(struct work_struct *work)
+{
+	struct svc_expkey *key = container_of(work, struct svc_expkey, ek_work);
+	cache_force_expire(key->cd, &key->h);
 }
 
 static inline void expkey_update(struct cache_head *cnew,

@@ -218,16 +246,19 @@ static inline void expkey_update(struct cache_head *cnew,
 	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
 	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);
 
+	init_fs_pin(&new->ek_pin, expkey_pin_kill);
 	new->ek_path = item->ek_path;
-	path_get(&item->ek_path);
+	path_get_pin(&new->ek_path, &new->ek_pin);
 }
 
 static struct cache_head *expkey_alloc(void)
 {
-	struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL);
-	if (i)
+	struct svc_expkey *i = kzalloc(sizeof(*i), GFP_KERNEL);
+	if (i) {
+		INIT_WORK(&i->ek_work, expkey_close_work);
+		init_completion(&i->ek_done);
 		return &i->h;
-	else
+	} else
 		return NULL;
 }
 

@@ -306,14 +337,21 @@ static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc)
 	fsloc->locations = NULL;
 }
 
-static void svc_export_put(struct kref *ref)
+static void svc_export_destroy(struct svc_export *exp)
 {
-	struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
-	path_put(&exp->ex_path);
 	auth_domain_put(exp->ex_client);
 	nfsd4_fslocs_free(&exp->ex_fslocs);
 	kfree(exp->ex_uuid);
-	kfree(exp);
+	kfree_rcu(exp, rcu_head);
+}
+
+static void svc_export_put(struct kref *ref)
+{
+	struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
+
+	rcu_read_lock();
+	complete(&exp->ex_done);
+	pin_kill(&exp->ex_pin);
 }
 
 static void svc_export_request(struct cache_detail *cd,

@@ -520,7 +558,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
 		return -EINVAL;
 	mesg[mlen-1] = 0;
 
-	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 

@@ -694,15 +732,34 @@ static int svc_export_match(struct cache_head *a, struct cache_head *b)
 		path_equal(&orig->ex_path, &new->ex_path);
 }
 
+static void export_pin_kill(struct fs_pin *pin)
+{
+	struct svc_export *exp = container_of(pin, struct svc_export, ex_pin);
+
+	if (!completion_done(&exp->ex_done)) {
+		schedule_work(&exp->ex_work);
+		wait_for_completion(&exp->ex_done);
+	}
+	path_put_unpin(&exp->ex_path, &exp->ex_pin);
+	svc_export_destroy(exp);
+}
+
+static void export_close_work(struct work_struct *work)
+{
+	struct svc_export *exp = container_of(work, struct svc_export, ex_work);
+	cache_force_expire(exp->cd, &exp->h);
+}
+
 static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)
 {
 	struct svc_export *new = container_of(cnew, struct svc_export, h);
 	struct svc_export *item = container_of(citem, struct svc_export, h);
 
+	init_fs_pin(&new->ex_pin, export_pin_kill);
 	kref_get(&item->ex_client->ref);
 	new->ex_client = item->ex_client;
 	new->ex_path = item->ex_path;
-	path_get(&item->ex_path);
+	path_get_pin(&new->ex_path, &new->ex_pin);
 	new->ex_fslocs.locations = NULL;
 	new->ex_fslocs.locations_count = 0;
 	new->ex_fslocs.migrated = 0;

@@ -740,10 +797,12 @@ static void export_update(struct cache_head *cnew, struct cache_head *citem)
 
 static struct cache_head *svc_export_alloc(void)
 {
-	struct svc_export *i = kmalloc(sizeof(*i), GFP_KERNEL);
-	if (i)
+	struct svc_export *i = kzalloc(sizeof(*i), GFP_KERNEL);
+	if (i) {
+		INIT_WORK(&i->ex_work, export_close_work);
+		init_completion(&i->ex_done);
 		return &i->h;
-	else
+	} else
 		return NULL;
 }
 

@@ -811,6 +870,7 @@ exp_find_key(struct cache_detail *cd, struct auth_domain *clp, int fsid_type,
 
 	key.ek_client = clp;
 	key.ek_fsidtype = fsid_type;
+	key.cd = cd;
 	memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
 
 	ek = svc_expkey_lookup(cd, &key);

index 1f52bfc..ff8905d 100644
@@ -4,6 +4,7 @@
 #ifndef NFSD_EXPORT_H
 #define NFSD_EXPORT_H
 
+#include <linux/fs_pin.h>
 #include <linux/sunrpc/cache.h>
 #include <uapi/linux/nfsd/export.h>
 

@@ -46,6 +47,8 @@ struct exp_flavor_info {
 
 struct svc_export {
 	struct cache_head	h;
+	struct cache_detail	*cd;
+
 	struct auth_domain *	ex_client;
 	int			ex_flags;
 	struct path		ex_path;

@@ -58,7 +61,13 @@ struct svc_export {
 	struct exp_flavor_info	ex_flavors[MAX_SECINFO_LIST];
 	enum pnfs_layouttype	ex_layout_type;
 	struct nfsd4_deviceid_map *ex_devid_map;
-	struct cache_detail	*cd;
+
+	struct fs_pin		ex_pin;
+	struct rcu_head		rcu_head;
+
+	/* For cache_put and fs umounting window */
+	struct completion	ex_done;
+	struct work_struct	ex_work;
 };
 
 /* an "export key" (expkey) maps a filehandlefragement to an

@@ -67,12 +76,19 @@ struct svc_export {
  */
 struct svc_expkey {
 	struct cache_head	h;
+	struct cache_detail	*cd;
 
 	struct auth_domain *	ek_client;
 	int			ek_fsidtype;
 	u32			ek_fsid[6];
 
 	struct path		ek_path;
+	struct fs_pin		ek_pin;
+	struct rcu_head		rcu_head;
+
+	/* For cache_put and fs umounting window */
+	struct completion	ek_done;
+	struct work_struct	ek_work;
 };
 
 #define EX_ISSYNC(exp)		(!((exp)->ex_flags & NFSEXP_ASYNC))