Merge branch 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache and mountpoint updates from Al Viro:
 "Saner handling of refcounts to mountpoints.

  Transfer the counting reference from struct mount ->mnt_mountpoint
  over to struct mountpoint ->m_dentry. That allows us to get rid of the
  convoluted games with ordering of mount shutdowns.

  The cost is in teaching shrink_dcache_{parent,for_umount} to cope with
  mixed-filesystem shrink lists, which we'll also need for the Slab
  Movable Objects patchset"

* 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch the remnants of releasing the mountpoint away from fs_pin
  get rid of detach_mnt()
  make struct mountpoint bear the dentry reference to mountpoint, not struct mount
  Teach shrink_dcache_parent() to cope with mixed-filesystem shrink lists
  fs/namespace.c: shift put_mountpoint() to callers of unhash_mnt()
  __detach_mounts(): lookup_mountpoint() can't return ERR_PTR() anymore
  nfs: dget_parent() never returns NULL
  ceph: don't open-code the check for dead lockref

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index aab29f48c62da2fbef1a6cf803cc6b753dfdc762..4ca0b8ff9a7270c7479fa13920cce5570df8e1ee 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1267,7 +1267,7 @@ __dentry_leases_walk(struct ceph_mds_client *mdsc,
                if (!spin_trylock(&dentry->d_lock))
                        continue;
 
-               if (dentry->d_lockref.count < 0) {
+               if (__lockref_is_dead(&dentry->d_lockref)) {
                        list_del_init(&di->lease_list);
                        goto next;
                }

diff --git a/fs/dcache.c b/fs/dcache.c
index f41121e5d1ec09462b425a7bbff004e788e26fd3..e88cf0554e65907d0136595a4521fc06fd521da4 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -861,6 +861,32 @@ void dput(struct dentry *dentry)
 }
 EXPORT_SYMBOL(dput);
 
+static void __dput_to_list(struct dentry *dentry, struct list_head *list)
+__must_hold(&dentry->d_lock)
+{
+       if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+               /* let the owner of the list it's on deal with it */
+               --dentry->d_lockref.count;
+       } else {
+               if (dentry->d_flags & DCACHE_LRU_LIST)
+                       d_lru_del(dentry);
+               if (!--dentry->d_lockref.count)
+                       d_shrink_add(dentry, list);
+       }
+}
+
+void dput_to_list(struct dentry *dentry, struct list_head *list)
+{
+       rcu_read_lock();
+       if (likely(fast_dput(dentry))) {
+               rcu_read_unlock();
+               return;
+       }
+       rcu_read_unlock();
+       if (!retain_dentry(dentry))
+               __dput_to_list(dentry, list);
+       spin_unlock(&dentry->d_lock);
+}
 
 /* This must be called with d_lock held */
 static inline void __dget_dlock(struct dentry *dentry)
@@ -1067,7 +1093,7 @@ out:
        return false;
 }
 
-static void shrink_dentry_list(struct list_head *list)
+void shrink_dentry_list(struct list_head *list)
 {
        while (!list_empty(list)) {
                struct dentry *dentry, *parent;
@@ -1089,18 +1115,9 @@ static void shrink_dentry_list(struct list_head *list)
                rcu_read_unlock();
                d_shrink_del(dentry);
                parent = dentry->d_parent;
+               if (parent != dentry)
+                       __dput_to_list(parent, list);
                __dentry_kill(dentry);
-               if (parent == dentry)
-                       continue;
-               /*
-                * We need to prune ancestors too. This is necessary to prevent
-                * quadratic behavior of shrink_dcache_parent(), but is also
-                * expected to be beneficial in reducing dentry cache
-                * fragmentation.
-                */
-               dentry = parent;
-               while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
-                       dentry = dentry_kill(dentry);
        }
 }
 
@@ -1445,8 +1462,11 @@ out:
 
 struct select_data {
        struct dentry *start;
+       union {
+               long found;
+               struct dentry *victim;
+       };
        struct list_head dispose;
-       int found;
 };
 
 static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
@@ -1478,6 +1498,37 @@ out:
        return ret;
 }
 
+static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
+{
+       struct select_data *data = _data;
+       enum d_walk_ret ret = D_WALK_CONTINUE;
+
+       if (data->start == dentry)
+               goto out;
+
+       if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+               if (!dentry->d_lockref.count) {
+                       rcu_read_lock();
+                       data->victim = dentry;
+                       return D_WALK_QUIT;
+               }
+       } else {
+               if (dentry->d_flags & DCACHE_LRU_LIST)
+                       d_lru_del(dentry);
+               if (!dentry->d_lockref.count)
+                       d_shrink_add(dentry, &data->dispose);
+       }
+       /*
+        * We can return to the caller if we have found some (this
+        * ensures forward progress). We'll be coming back to find
+        * the rest.
+        */
+       if (!list_empty(&data->dispose))
+               ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
+out:
+       return ret;
+}
+
 /**
  * shrink_dcache_parent - prune dcache
  * @parent: parent of entries to prune
@@ -1487,12 +1538,9 @@ out:
 void shrink_dcache_parent(struct dentry *parent)
 {
        for (;;) {
-               struct select_data data;
+               struct select_data data = {.start = parent};
 
                INIT_LIST_HEAD(&data.dispose);
-               data.start = parent;
-               data.found = 0;
-
                d_walk(parent, &data, select_collect);
 
                if (!list_empty(&data.dispose)) {
@@ -1503,6 +1551,24 @@ void shrink_dcache_parent(struct dentry *parent)
                cond_resched();
                if (!data.found)
                        break;
+               data.victim = NULL;
+               d_walk(parent, &data, select_collect2);
+               if (data.victim) {
+                       struct dentry *parent;
+                       spin_lock(&data.victim->d_lock);
+                       if (!shrink_lock_dentry(data.victim)) {
+                               spin_unlock(&data.victim->d_lock);
+                               rcu_read_unlock();
+                       } else {
+                               rcu_read_unlock();
+                               parent = data.victim->d_parent;
+                               if (parent != data.victim)
+                                       __dput_to_list(parent, &data.dispose);
+                               __dentry_kill(data.victim);
+                       }
+               }
+               if (!list_empty(&data.dispose))
+                       shrink_dentry_list(&data.dispose);
        }
 }
 EXPORT_SYMBOL(shrink_dcache_parent);

diff --git a/fs/fs_pin.c b/fs/fs_pin.c
index a6497cf8ae53aa2bc7dcc2996887fcb92f1e9820..47ef3c71ce907789994f73e49b2d6b072022463e 100644 (file)
--- 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/internal.h b/fs/internal.h
index ff5173212803b2e6a57335e2e2216e422af746e6..315fcd8d237ccb7264aa06f15e7d6c977ab52bf5 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -157,6 +157,8 @@ extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
 extern struct dentry *d_alloc_cursor(struct dentry *);
 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
 extern char *simple_dname(struct dentry *, char *, int);
+extern void dput_to_list(struct dentry *, struct list_head *);
+extern void shrink_dentry_list(struct list_head *);
 
 /*
  * read_write.c

diff --git a/fs/mount.h b/fs/mount.h
index 6250de544760e1ed28bd1e91df35f45ad29d9e8c..711a4093e475e9fdf9fb8df1d81ab289ee33a498 100644 (file)
--- 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;
@@ -68,8 +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 dentry *mnt_ex_mountpoint;
+       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 f0d664adb9ba731abcfff90f886b3f03a923381f..6464ea4acba9418f489fe8d5f867f55ef232b4e3 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -70,6 +70,8 @@ static struct hlist_head *mount_hashtable __read_mostly;
 static struct hlist_head *mountpoint_hashtable __read_mostly;
 static struct kmem_cache *mnt_cache __read_mostly;
 static DECLARE_RWSEM(namespace_sem);
+static HLIST_HEAD(unmounted);  /* protected by namespace_sem */
+static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */
 
 /* /sys/fs */
 struct kobject *fs_kobj;
@@ -170,14 +172,6 @@ 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);
-       dput(m->mnt_ex_mountpoint);
-       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 +209,7 @@ 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;
 
@@ -740,7 +734,7 @@ mountpoint:
 
        /* Add the new mountpoint to the hash table */
        read_seqlock_excl(&mount_lock);
-       new->m_dentry = dentry;
+       new->m_dentry = dget(dentry);
        new->m_count = 1;
        hlist_add_head(&new->m_hash, mp_hash(dentry));
        INIT_HLIST_HEAD(&new->m_list);
@@ -753,7 +747,11 @@ done:
        return mp;
 }
 
-static void put_mountpoint(struct mountpoint *mp)
+/*
+ * vfsmount lock must be held.  Additionally, the caller is responsible
+ * for serializing calls for given disposal list.
+ */
+static void __put_mountpoint(struct mountpoint *mp, struct list_head *list)
 {
        if (!--mp->m_count) {
                struct dentry *dentry = mp->m_dentry;
@@ -761,11 +759,18 @@ static void put_mountpoint(struct mountpoint *mp)
                spin_lock(&dentry->d_lock);
                dentry->d_flags &= ~DCACHE_MOUNTED;
                spin_unlock(&dentry->d_lock);
+               dput_to_list(dentry, list);
                hlist_del(&mp->m_hash);
                kfree(mp);
        }
 }
 
+/* called with namespace_lock and vfsmount lock */
+static void put_mountpoint(struct mountpoint *mp)
+{
+       __put_mountpoint(mp, &ex_mountpoints);
+}
+
 static inline int check_mnt(struct mount *mnt)
 {
        return mnt->mnt_ns == current->nsproxy->mnt_ns;
@@ -796,25 +801,17 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns)
 /*
  * vfsmount lock must be held for write
  */
-static void unhash_mnt(struct mount *mnt)
+static struct mountpoint *unhash_mnt(struct mount *mnt)
 {
+       struct mountpoint *mp;
        mnt->mnt_parent = mnt;
        mnt->mnt_mountpoint = mnt->mnt.mnt_root;
        list_del_init(&mnt->mnt_child);
        hlist_del_init_rcu(&mnt->mnt_hash);
        hlist_del_init(&mnt->mnt_mp_list);
-       put_mountpoint(mnt->mnt_mp);
+       mp = mnt->mnt_mp;
        mnt->mnt_mp = NULL;
-}
-
-/*
- * vfsmount lock must be held for write
- */
-static void detach_mnt(struct mount *mnt, struct path *old_path)
-{
-       old_path->dentry = mnt->mnt_mountpoint;
-       old_path->mnt = &mnt->mnt_parent->mnt;
-       unhash_mnt(mnt);
+       return mp;
 }
 
 /*
@@ -822,9 +819,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
  */
 static void umount_mnt(struct mount *mnt)
 {
-       /* old mountpoint will be dropped when we can do that */
-       mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint;
-       unhash_mnt(mnt);
+       put_mountpoint(unhash_mnt(mnt));
 }
 
 /*
@@ -836,7 +831,7 @@ void mnt_set_mountpoint(struct mount *mnt,
 {
        mp->m_count++;
        mnt_add_count(mnt, 1);  /* essentially, that's mntget */
-       child_mnt->mnt_mountpoint = dget(mp->m_dentry);
+       child_mnt->mnt_mountpoint = mp->m_dentry;
        child_mnt->mnt_parent = mnt;
        child_mnt->mnt_mp = mp;
        hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list);
@@ -863,7 +858,6 @@ static void attach_mnt(struct mount *mnt,
 void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)
 {
        struct mountpoint *old_mp = mnt->mnt_mp;
-       struct dentry *old_mountpoint = mnt->mnt_mountpoint;
        struct mount *old_parent = mnt->mnt_parent;
 
        list_del_init(&mnt->mnt_child);
@@ -873,22 +867,6 @@ void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct m
        attach_mnt(mnt, parent, mp);
 
        put_mountpoint(old_mp);
-
-       /*
-        * Safely avoid even the suggestion this code might sleep or
-        * lock the mount hash by taking advantage of the knowledge that
-        * mnt_change_mountpoint will not release the final reference
-        * to a mountpoint.
-        *
-        * During mounting, the mount passed in as the parent mount will
-        * continue to use the old mountpoint and during unmounting, the
-        * old mountpoint will continue to exist until namespace_unlock,
-        * which happens well after mnt_change_mountpoint.
-        */
-       spin_lock(&old_mountpoint->d_lock);
-       old_mountpoint->d_lockref.count--;
-       spin_unlock(&old_mountpoint->d_lock);
-
        mnt_add_count(old_parent, -1);
 }
 
@@ -1103,19 +1081,22 @@ 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);
@@ -1141,6 +1122,8 @@ static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
 
 static void mntput_no_expire(struct mount *mnt)
 {
+       LIST_HEAD(list);
+
        rcu_read_lock();
        if (likely(READ_ONCE(mnt->mnt_ns))) {
                /*
@@ -1181,10 +1164,12 @@ static void mntput_no_expire(struct mount *mnt)
        if (unlikely(!list_empty(&mnt->mnt_mounts))) {
                struct mount *p, *tmp;
                list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts,  mnt_child) {
-                       umount_mnt(p);
+                       __put_mountpoint(unhash_mnt(p), &list);
+                       hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children);
                }
        }
        unlock_mount_hash();
+       shrink_dentry_list(&list);
 
        if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) {
                struct task_struct *task = current;
@@ -1370,22 +1355,29 @@ int may_umount(struct vfsmount *mnt)
 
 EXPORT_SYMBOL(may_umount);
 
-static HLIST_HEAD(unmounted);  /* protected by namespace_sem */
-
 static void namespace_unlock(void)
 {
        struct hlist_head head;
+       struct hlist_node *p;
+       struct mount *m;
+       LIST_HEAD(list);
 
        hlist_move_list(&unmounted, &head);
+       list_splice_init(&ex_mountpoints, &list);
 
        up_write(&namespace_sem);
 
+       shrink_dentry_list(&list);
+
        if (likely(hlist_empty(&head)))
                return;
 
        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)
@@ -1472,8 +1464,6 @@ 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) {
@@ -1481,6 +1471,7 @@ 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);
@@ -1626,15 +1617,15 @@ void __detach_mounts(struct dentry *dentry)
        namespace_lock();
        lock_mount_hash();
        mp = lookup_mountpoint(dentry);
-       if (IS_ERR_OR_NULL(mp))
+       if (!mp)
                goto out_unlock;
 
        event++;
        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);
        }
@@ -2046,7 +2037,7 @@ int count_mounts(struct mnt_namespace *ns, struct mount *mnt)
 static int attach_recursive_mnt(struct mount *source_mnt,
                        struct mount *dest_mnt,
                        struct mountpoint *dest_mp,
-                       struct path *parent_path)
+                       bool moving)
 {
        struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
        HLIST_HEAD(tree_list);
@@ -2064,7 +2055,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
                return PTR_ERR(smp);
 
        /* Is there space to add these mounts to the mount namespace? */
-       if (!parent_path) {
+       if (!moving) {
                err = count_mounts(ns, source_mnt);
                if (err)
                        goto out;
@@ -2083,8 +2074,8 @@ static int attach_recursive_mnt(struct mount *source_mnt,
        } else {
                lock_mount_hash();
        }
-       if (parent_path) {
-               detach_mnt(source_mnt, parent_path);
+       if (moving) {
+               unhash_mnt(source_mnt);
                attach_mnt(source_mnt, dest_mnt, dest_mp);
                touch_mnt_namespace(source_mnt->mnt_ns);
        } else {
@@ -2182,7 +2173,7 @@ static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
              d_is_dir(mnt->mnt.mnt_root))
                return -ENOTDIR;
 
-       return attach_recursive_mnt(mnt, p, mp, NULL);
+       return attach_recursive_mnt(mnt, p, mp, false);
 }
 
 /*
@@ -2575,11 +2566,11 @@ out:
 
 static int do_move_mount(struct path *old_path, struct path *new_path)
 {
-       struct path parent_path = {.mnt = NULL, .dentry = NULL};
        struct mnt_namespace *ns;
        struct mount *p;
        struct mount *old;
-       struct mountpoint *mp;
+       struct mount *parent;
+       struct mountpoint *mp, *old_mp;
        int err;
        bool attached;
 
@@ -2589,7 +2580,9 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
 
        old = real_mount(old_path->mnt);
        p = real_mount(new_path->mnt);
+       parent = old->mnt_parent;
        attached = mnt_has_parent(old);
+       old_mp = old->mnt_mp;
        ns = old->mnt_ns;
 
        err = -EINVAL;
@@ -2617,7 +2610,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
        /*
         * Don't move a mount residing in a shared parent.
         */
-       if (attached && IS_MNT_SHARED(old->mnt_parent))
+       if (attached && IS_MNT_SHARED(parent))
                goto out;
        /*
         * Don't move a mount tree containing unbindable mounts to a destination
@@ -2633,18 +2626,21 @@ static int do_move_mount(struct path *old_path, struct path *new_path)
                        goto out;
 
        err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,
-                                  attached ? &parent_path : NULL);
+                                  attached);
        if (err)
                goto out;
 
        /* if the mount is moved, it should no longer be expire
         * automatically */
        list_del_init(&old->mnt_expire);
+       if (attached)
+               put_mountpoint(old_mp);
 out:
        unlock_mount(mp);
        if (!err) {
-               path_put(&parent_path);
-               if (!attached)
+               if (attached)
+                       mntput_no_expire(parent);
+               else
                        free_mnt_ns(ns);
        }
        return err;
@@ -3589,8 +3585,8 @@ EXPORT_SYMBOL(path_is_under);
 SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
                const char __user *, put_old)
 {
-       struct path new, old, parent_path, root_parent, root;
-       struct mount *new_mnt, *root_mnt, *old_mnt;
+       struct path new, old, root;
+       struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;
        struct mountpoint *old_mp, *root_mp;
        int error;
 
@@ -3619,9 +3615,11 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        new_mnt = real_mount(new.mnt);
        root_mnt = real_mount(root.mnt);
        old_mnt = real_mount(old.mnt);
+       ex_parent = new_mnt->mnt_parent;
+       root_parent = root_mnt->mnt_parent;
        if (IS_MNT_SHARED(old_mnt) ||
-               IS_MNT_SHARED(new_mnt->mnt_parent) ||
-               IS_MNT_SHARED(root_mnt->mnt_parent))
+               IS_MNT_SHARED(ex_parent) ||
+               IS_MNT_SHARED(root_parent))
                goto out4;
        if (!check_mnt(root_mnt) || !check_mnt(new_mnt))
                goto out4;
@@ -3638,7 +3636,6 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
                goto out4; /* not a mountpoint */
        if (!mnt_has_parent(root_mnt))
                goto out4; /* not attached */
-       root_mp = root_mnt->mnt_mp;
        if (new.mnt->mnt_root != new.dentry)
                goto out4; /* not a mountpoint */
        if (!mnt_has_parent(new_mnt))
@@ -3649,10 +3646,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        /* make certain new is below the root */
        if (!is_path_reachable(new_mnt, new.dentry, &root))
                goto out4;
-       root_mp->m_count++; /* pin it so it won't go away */
        lock_mount_hash();
-       detach_mnt(new_mnt, &parent_path);
-       detach_mnt(root_mnt, &root_parent);
+       umount_mnt(new_mnt);
+       root_mp = unhash_mnt(root_mnt);  /* we'll need its mountpoint */
        if (root_mnt->mnt.mnt_flags & MNT_LOCKED) {
                new_mnt->mnt.mnt_flags |= MNT_LOCKED;
                root_mnt->mnt.mnt_flags &= ~MNT_LOCKED;
@@ -3660,7 +3656,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        /* mount old root on put_old */
        attach_mnt(root_mnt, old_mnt, old_mp);
        /* mount new_root on / */
-       attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp);
+       attach_mnt(new_mnt, root_parent, root_mp);
+       mnt_add_count(root_parent, -1);
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        /* A moved mount should not expire automatically */
        list_del_init(&new_mnt->mnt_expire);
@@ -3670,10 +3667,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        error = 0;
 out4:
        unlock_mount(old_mp);
-       if (!error) {
-               path_put(&root_parent);
-               path_put(&parent_path);
-       }
+       if (!error)
+               mntput_no_expire(ex_parent);
 out3:
        path_put(&root);
 out2:

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 3683d2b1cc8e3d331174c4918c4ae052211ab405..628631e2e34fe630f6e24a814f43551d93484135 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -457,10 +457,8 @@ int nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
                struct dentry *pd_dentry;
 
                pd_dentry = dget_parent(dentry);
-               if (pd_dentry != NULL) {
-                       nfs_zap_caches(d_inode(pd_dentry));
-                       dput(pd_dentry);
-               }
+               nfs_zap_caches(d_inode(pd_dentry));
+               dput(pd_dentry);
        }
        nfs_free_fattr(res.fattr);
        if (error < 0)

diff --git a/include/linux/fs_pin.h b/include/linux/fs_pin.h
index 7cab74d66f85476ff20c0445edc1164115091ca2..bdd09fd2520c00f9e4ca977a25d6da934f285ece 100644 (file)
--- 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 *);