Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  [PATCH] mnt_expire is protected by namespace_sem, no need for vfsmount_lock
  [PATCH] do shrink_submounts() for all fs types
  [PATCH] sanitize locking in mark_mounts_for_expiry() and shrink_submounts()
  [PATCH] count ghost references to vfsmounts
  [PATCH] reduce stack footprint in namespace.c

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 5ca3625..9ba16ed 100644 (file)
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -573,7 +573,6 @@ extern const struct file_operations afs_mntpt_file_operations;
 
 extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
 extern void afs_mntpt_kill_timer(void);
-extern void afs_umount_begin(struct vfsmount *, int);
 
 /*
  * proc.c

diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index a3510b8..2f55039 100644 (file)
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -283,11 +283,3 @@ void afs_mntpt_kill_timer(void)
        cancel_delayed_work(&afs_mntpt_expiry_timer);
        flush_scheduled_work();
 }
-
-/*
- * begin unmount by attempting to remove all automounted mountpoints we added
- */
-void afs_umount_begin(struct vfsmount *vfsmnt, int flags)
-{
-       shrink_submounts(vfsmnt, &afs_vfsmounts);
-}

diff --git a/fs/afs/super.c b/fs/afs/super.c
index 36bbce4..4b572b8 100644 (file)
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -50,7 +50,6 @@ static const struct super_operations afs_super_ops = {
        .write_inode    = afs_write_inode,
        .destroy_inode  = afs_destroy_inode,
        .clear_inode    = afs_clear_inode,
-       .umount_begin   = afs_umount_begin,
        .put_super      = afs_put_super,
        .show_options   = generic_show_options,
 };

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index a1a95b0..56c9240 100644 (file)
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -33,7 +33,6 @@ void dfs_shrink_umount_helper(struct vfsmount *vfsmnt)
 {
        mark_mounts_for_expiry(&cifs_dfs_automount_list);
        mark_mounts_for_expiry(&cifs_dfs_automount_list);
-       shrink_submounts(vfsmnt, &cifs_dfs_automount_list);
 }
 
 /**

diff --git a/fs/namespace.c b/fs/namespace.c
index 7953c96..94f026e 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -155,15 +155,15 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns)
        }
 }
 
-static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
+static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
 {
-       old_nd->path.dentry = mnt->mnt_mountpoint;
-       old_nd->path.mnt = mnt->mnt_parent;
+       old_path->dentry = mnt->mnt_mountpoint;
+       old_path->mnt = mnt->mnt_parent;
        mnt->mnt_parent = mnt;
        mnt->mnt_mountpoint = mnt->mnt_root;
        list_del_init(&mnt->mnt_child);
        list_del_init(&mnt->mnt_hash);
-       old_nd->path.dentry->d_mounted--;
+       old_path->dentry->d_mounted--;
 }
 
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
@@ -174,12 +174,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
        dentry->d_mounted++;
 }
 
-static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
+static void attach_mnt(struct vfsmount *mnt, struct path *path)
 {
-       mnt_set_mountpoint(nd->path.mnt, nd->path.dentry, mnt);
+       mnt_set_mountpoint(path->mnt, path->dentry, mnt);
        list_add_tail(&mnt->mnt_hash, mount_hashtable +
-                       hash(nd->path.mnt, nd->path.dentry));
-       list_add_tail(&mnt->mnt_child, &nd->path.mnt->mnt_mounts);
+                       hash(path->mnt, path->dentry));
+       list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
 }
 
 /*
@@ -262,10 +262,8 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
                /* stick the duplicate mount on the same expiry list
                 * as the original if that was on one */
                if (flag & CL_EXPIRE) {
-                       spin_lock(&vfsmount_lock);
                        if (!list_empty(&old->mnt_expire))
                                list_add(&mnt->mnt_expire, &old->mnt_expire);
-                       spin_unlock(&vfsmount_lock);
                }
        }
        return mnt;
@@ -548,6 +546,7 @@ void release_mounts(struct list_head *head)
                        m = mnt->mnt_parent;
                        mnt->mnt_mountpoint = mnt->mnt_root;
                        mnt->mnt_parent = mnt;
+                       m->mnt_ghosts--;
                        spin_unlock(&vfsmount_lock);
                        dput(dentry);
                        mntput(m);
@@ -572,12 +571,16 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
                __touch_mnt_namespace(p->mnt_ns);
                p->mnt_ns = NULL;
                list_del_init(&p->mnt_child);
-               if (p->mnt_parent != p)
+               if (p->mnt_parent != p) {
+                       p->mnt_parent->mnt_ghosts++;
                        p->mnt_mountpoint->d_mounted--;
+               }
                change_mnt_propagation(p, MS_PRIVATE);
        }
 }
 
+static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);
+
 static int do_umount(struct vfsmount *mnt, int flags)
 {
        struct super_block *sb = mnt->mnt_sb;
@@ -650,6 +653,9 @@ static int do_umount(struct vfsmount *mnt, int flags)
        spin_lock(&vfsmount_lock);
        event++;
 
+       if (!(flags & MNT_DETACH))
+               shrink_submounts(mnt, &umount_list);
+
        retval = -EBUSY;
        if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
                if (!list_empty(&mnt->mnt_list))
@@ -744,7 +750,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                        int flag)
 {
        struct vfsmount *res, *p, *q, *r, *s;
-       struct nameidata nd;
+       struct path path;
 
        if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
                return NULL;
@@ -769,14 +775,14 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                q = q->mnt_parent;
                        }
                        p = s;
-                       nd.path.mnt = q;
-                       nd.path.dentry = p->mnt_mountpoint;
+                       path.mnt = q;
+                       path.dentry = p->mnt_mountpoint;
                        q = clone_mnt(p, p->mnt_root, flag);
                        if (!q)
                                goto Enomem;
                        spin_lock(&vfsmount_lock);
                        list_add_tail(&q->mnt_list, &res->mnt_list);
-                       attach_mnt(q, &nd);
+                       attach_mnt(q, &path);
                        spin_unlock(&vfsmount_lock);
                }
        }
@@ -876,11 +882,11 @@ void drop_collected_mounts(struct vfsmount *mnt)
  * in allocations.
  */
 static int attach_recursive_mnt(struct vfsmount *source_mnt,
-                       struct nameidata *nd, struct nameidata *parent_nd)
+                       struct path *path, struct path *parent_path)
 {
        LIST_HEAD(tree_list);
-       struct vfsmount *dest_mnt = nd->path.mnt;
-       struct dentry *dest_dentry = nd->path.dentry;
+       struct vfsmount *dest_mnt = path->mnt;
+       struct dentry *dest_dentry = path->dentry;
        struct vfsmount *child, *p;
 
        if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
@@ -892,9 +898,9 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
        }
 
        spin_lock(&vfsmount_lock);
-       if (parent_nd) {
-               detach_mnt(source_mnt, parent_nd);
-               attach_mnt(source_mnt, nd);
+       if (parent_path) {
+               detach_mnt(source_mnt, parent_path);
+               attach_mnt(source_mnt, path);
                touch_mnt_namespace(current->nsproxy->mnt_ns);
        } else {
                mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
@@ -930,7 +936,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
 
        err = -ENOENT;
        if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))
-               err = attach_recursive_mnt(mnt, nd, NULL);
+               err = attach_recursive_mnt(mnt, &nd->path, NULL);
 out_unlock:
        mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
        if (!err)
@@ -1059,7 +1065,8 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt)
  */
 static noinline int do_move_mount(struct nameidata *nd, char *old_name)
 {
-       struct nameidata old_nd, parent_nd;
+       struct nameidata old_nd;
+       struct path parent_path;
        struct vfsmount *p;
        int err = 0;
        if (!capable(CAP_SYS_ADMIN))
@@ -1114,21 +1121,19 @@ static noinline int do_move_mount(struct nameidata *nd, char *old_name)
                if (p == old_nd.path.mnt)
                        goto out1;
 
-       err = attach_recursive_mnt(old_nd.path.mnt, nd, &parent_nd);
+       err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path);
        if (err)
                goto out1;
 
-       spin_lock(&vfsmount_lock);
        /* if the mount is moved, it should no longer be expire
         * automatically */
        list_del_init(&old_nd.path.mnt->mnt_expire);
-       spin_unlock(&vfsmount_lock);
 out1:
        mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
 out:
        up_write(&namespace_sem);
        if (!err)
-               path_put(&parent_nd.path);
+               path_put(&parent_path);
        path_put(&old_nd.path);
        return err;
 }
@@ -1189,12 +1194,9 @@ int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
        if ((err = graft_tree(newmnt, nd)))
                goto unlock;
 
-       if (fslist) {
-               /* add to the specified expiration list */
-               spin_lock(&vfsmount_lock);
+       if (fslist) /* add to the specified expiration list */
                list_add_tail(&newmnt->mnt_expire, fslist);
-               spin_unlock(&vfsmount_lock);
-       }
+
        up_write(&namespace_sem);
        return 0;
 
@@ -1206,75 +1208,6 @@ unlock:
 
 EXPORT_SYMBOL_GPL(do_add_mount);
 
-static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
-                               struct list_head *umounts)
-{
-       spin_lock(&vfsmount_lock);
-
-       /*
-        * Check if mount is still attached, if not, let whoever holds it deal
-        * with the sucker
-        */
-       if (mnt->mnt_parent == mnt) {
-               spin_unlock(&vfsmount_lock);
-               return;
-       }
-
-       /*
-        * Check that it is still dead: the count should now be 2 - as
-        * contributed by the vfsmount parent and the mntget above
-        */
-       if (!propagate_mount_busy(mnt, 2)) {
-               /* delete from the namespace */
-               touch_mnt_namespace(mnt->mnt_ns);
-               list_del_init(&mnt->mnt_list);
-               mnt->mnt_ns = NULL;
-               umount_tree(mnt, 1, umounts);
-               spin_unlock(&vfsmount_lock);
-       } else {
-               /*
-                * Someone brought it back to life whilst we didn't have any
-                * locks held so return it to the expiration list
-                */
-               list_add_tail(&mnt->mnt_expire, mounts);
-               spin_unlock(&vfsmount_lock);
-       }
-}
-
-/*
- * go through the vfsmounts we've just consigned to the graveyard to
- * - check that they're still dead
- * - delete the vfsmount from the appropriate namespace under lock
- * - dispose of the corpse
- */
-static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts)
-{
-       struct mnt_namespace *ns;
-       struct vfsmount *mnt;
-
-       while (!list_empty(graveyard)) {
-               LIST_HEAD(umounts);
-               mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire);
-               list_del_init(&mnt->mnt_expire);
-
-               /* don't do anything if the namespace is dead - all the
-                * vfsmounts from it are going away anyway */
-               ns = mnt->mnt_ns;
-               if (!ns || !ns->root)
-                       continue;
-               get_mnt_ns(ns);
-
-               spin_unlock(&vfsmount_lock);
-               down_write(&namespace_sem);
-               expire_mount(mnt, mounts, &umounts);
-               up_write(&namespace_sem);
-               release_mounts(&umounts);
-               mntput(mnt);
-               put_mnt_ns(ns);
-               spin_lock(&vfsmount_lock);
-       }
-}
-
 /*
  * process a list of expirable mountpoints with the intent of discarding any
  * mountpoints that aren't in use and haven't been touched since last we came
@@ -1284,10 +1217,12 @@ void mark_mounts_for_expiry(struct list_head *mounts)
 {
        struct vfsmount *mnt, *next;
        LIST_HEAD(graveyard);
+       LIST_HEAD(umounts);
 
        if (list_empty(mounts))
                return;
 
+       down_write(&namespace_sem);
        spin_lock(&vfsmount_lock);
 
        /* extract from the expiration list every vfsmount that matches the
@@ -1298,16 +1233,19 @@ void mark_mounts_for_expiry(struct list_head *mounts)
         */
        list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
                if (!xchg(&mnt->mnt_expiry_mark, 1) ||
-                   atomic_read(&mnt->mnt_count) != 1)
+                       propagate_mount_busy(mnt, 1))
                        continue;
-
-               mntget(mnt);
                list_move(&mnt->mnt_expire, &graveyard);
        }
-
-       expire_mount_list(&graveyard, mounts);
-
+       while (!list_empty(&graveyard)) {
+               mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire);
+               touch_mnt_namespace(mnt->mnt_ns);
+               umount_tree(mnt, 1, &umounts);
+       }
        spin_unlock(&vfsmount_lock);
+       up_write(&namespace_sem);
+
+       release_mounts(&umounts);
 }
 
 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
@@ -1343,7 +1281,6 @@ resume:
                }
 
                if (!propagate_mount_busy(mnt, 1)) {
-                       mntget(mnt);
                        list_move_tail(&mnt->mnt_expire, graveyard);
                        found++;
                }
@@ -1363,22 +1300,22 @@ resume:
  * process a list of expirable mountpoints with the intent of discarding any
  * submounts of a specific parent mountpoint
  */
-void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts)
+static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts)
 {
        LIST_HEAD(graveyard);
-       int found;
-
-       spin_lock(&vfsmount_lock);
+       struct vfsmount *m;
 
        /* extract submounts of 'mountpoint' from the expiration list */
-       while ((found = select_submounts(mountpoint, &graveyard)) != 0)
-               expire_mount_list(&graveyard, mounts);
-
-       spin_unlock(&vfsmount_lock);
+       while (select_submounts(mnt, &graveyard)) {
+               while (!list_empty(&graveyard)) {
+                       m = list_first_entry(&graveyard, struct vfsmount,
+                                               mnt_expire);
+                       touch_mnt_namespace(mnt->mnt_ns);
+                       umount_tree(mnt, 1, umounts);
+               }
+       }
 }
 
-EXPORT_SYMBOL_GPL(shrink_submounts);
-
 /*
  * Some copy_from_user() implementations do not return the exact number of
  * bytes remaining to copy on a fault.  But copy_mount_options() requires that.
@@ -1683,7 +1620,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
                path_put(&old_pwd);
 }
 
-static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
+static void chroot_fs_refs(struct path *old_root, struct path *new_root)
 {
        struct task_struct *g, *p;
        struct fs_struct *fs;
@@ -1695,12 +1632,12 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
                if (fs) {
                        atomic_inc(&fs->count);
                        task_unlock(p);
-                       if (fs->root.dentry == old_nd->path.dentry
-                           && fs->root.mnt == old_nd->path.mnt)
-                               set_fs_root(fs, &new_nd->path);
-                       if (fs->pwd.dentry == old_nd->path.dentry
-                           && fs->pwd.mnt == old_nd->path.mnt)
-                               set_fs_pwd(fs, &new_nd->path);
+                       if (fs->root.dentry == old_root->dentry
+                           && fs->root.mnt == old_root->mnt)
+                               set_fs_root(fs, new_root);
+                       if (fs->pwd.dentry == old_root->dentry
+                           && fs->pwd.mnt == old_root->mnt)
+                               set_fs_pwd(fs, new_root);
                        put_fs_struct(fs);
                } else
                        task_unlock(p);
@@ -1737,7 +1674,8 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
                               const char __user * put_old)
 {
        struct vfsmount *tmp;
-       struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
+       struct nameidata new_nd, old_nd, user_nd;
+       struct path parent_path, root_parent;
        int error;
 
        if (!capable(CAP_SYS_ADMIN))
@@ -1811,19 +1749,19 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
                        goto out3;
        } else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))
                goto out3;
-       detach_mnt(new_nd.path.mnt, &parent_nd);
+       detach_mnt(new_nd.path.mnt, &parent_path);
        detach_mnt(user_nd.path.mnt, &root_parent);
        /* mount old root on put_old */
-       attach_mnt(user_nd.path.mnt, &old_nd);
+       attach_mnt(user_nd.path.mnt, &old_nd.path);
        /* mount new_root on / */
        attach_mnt(new_nd.path.mnt, &root_parent);
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        spin_unlock(&vfsmount_lock);
-       chroot_fs_refs(&user_nd, &new_nd);
+       chroot_fs_refs(&user_nd.path, &new_nd.path);
        security_sb_post_pivotroot(&user_nd, &new_nd);
        error = 0;
-       path_put(&root_parent.path);
-       path_put(&parent_nd.path);
+       path_put(&root_parent);
+       path_put(&parent_path);
 out2:
        mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);
        up_write(&namespace_sem);

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index dd4dfcd..f921902 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -589,8 +589,6 @@ static void nfs_umount_begin(struct vfsmount *vfsmnt, int flags)
        struct nfs_server *server = NFS_SB(vfsmnt->mnt_sb);
        struct rpc_clnt *rpc;
 
-       shrink_submounts(vfsmnt, &nfs_automount_list);
-
        if (!(flags & MNT_FORCE))
                return;
        /* -EIO all pending I/O */

diff --git a/fs/pnode.c b/fs/pnode.c
index 05ba692..1d8f544 100644 (file)
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -225,7 +225,7 @@ out:
  */
 static inline int do_refcount_check(struct vfsmount *mnt, int count)
 {
-       int mycount = atomic_read(&mnt->mnt_count);
+       int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
        return (mycount > count);
 }
 

diff --git a/include/linux/mount.h b/include/linux/mount.h
index 6d3047d..5ee2df2 100644 (file)
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -61,6 +61,7 @@ struct vfsmount {
        atomic_t mnt_count;
        int mnt_expiry_mark;            /* true if marked for expiry */
        int mnt_pinned;
+       int mnt_ghosts;
 };
 
 static inline struct vfsmount *mntget(struct vfsmount *mnt)
@@ -98,7 +99,6 @@ extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
                        int mnt_flags, struct list_head *fslist);
 
 extern void mark_mounts_for_expiry(struct list_head *mounts);
-extern void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts);
 
 extern spinlock_t vfsmount_lock;
 extern dev_t name_to_dev_t(char *name);