net/mlx5: Add MTPPS and MTPPSE registers infrastructure

[sfrench/cifs-2.6.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 9ad88a45b3e3b8ae6c3c89f15a07b049c9485f1f..487ba30bb5c67a8f66bdaadb5b13e8240c937f7a 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -96,10 +96,6 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)
        return &mountpoint_hashtable[tmp & mp_hash_mask];
 }
 
-/*
- * allocation is serialized by namespace_sem, but we need the spinlock to
- * serialize with freeing.
- */
 static int mnt_alloc_id(struct mount *mnt)
 {
        int res;
@@ -746,26 +742,50 @@ static struct mountpoint *lookup_mountpoint(struct dentry *dentry)
        return NULL;
 }
 
-static struct mountpoint *new_mountpoint(struct dentry *dentry)
+static struct mountpoint *get_mountpoint(struct dentry *dentry)
 {
-       struct hlist_head *chain = mp_hash(dentry);
-       struct mountpoint *mp;
+       struct mountpoint *mp, *new = NULL;
        int ret;
 
-       mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
-       if (!mp)
+       if (d_mountpoint(dentry)) {
+mountpoint:
+               read_seqlock_excl(&mount_lock);
+               mp = lookup_mountpoint(dentry);
+               read_sequnlock_excl(&mount_lock);
+               if (mp)
+                       goto done;
+       }
+
+       if (!new)
+               new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
+       if (!new)
                return ERR_PTR(-ENOMEM);
 
+
+       /* Exactly one processes may set d_mounted */
        ret = d_set_mounted(dentry);
-       if (ret) {
-               kfree(mp);
-               return ERR_PTR(ret);
-       }
 
-       mp->m_dentry = dentry;
-       mp->m_count = 1;
-       hlist_add_head(&mp->m_hash, chain);
-       INIT_HLIST_HEAD(&mp->m_list);
+       /* Someone else set d_mounted? */
+       if (ret == -EBUSY)
+               goto mountpoint;
+
+       /* The dentry is not available as a mountpoint? */
+       mp = ERR_PTR(ret);
+       if (ret)
+               goto done;
+
+       /* Add the new mountpoint to the hash table */
+       read_seqlock_excl(&mount_lock);
+       new->m_dentry = dentry;
+       new->m_count = 1;
+       hlist_add_head(&new->m_hash, mp_hash(dentry));
+       INIT_HLIST_HEAD(&new->m_list);
+       read_sequnlock_excl(&mount_lock);
+
+       mp = new;
+       new = NULL;
+done:
+       kfree(new);
        return mp;
 }
 
@@ -1034,6 +1054,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
                if (IS_MNT_SLAVE(old))
                        list_add(&mnt->mnt_slave, &old->mnt_slave);
                mnt->mnt_master = old->mnt_master;
+       } else {
+               CLEAR_MNT_SHARED(mnt);
        }
        if (flag & CL_MAKE_SHARED)
                set_mnt_shared(mnt);
@@ -1159,6 +1181,35 @@ struct vfsmount *mntget(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(mntget);
 
+/* path_is_mountpoint() - Check if path is a mount in the current
+ *                          namespace.
+ *
+ *  d_mountpoint() can only be used reliably to establish if a dentry is
+ *  not mounted in any namespace and that common case is handled inline.
+ *  d_mountpoint() isn't aware of the possibility there may be multiple
+ *  mounts using a given dentry in a different namespace. This function
+ *  checks if the passed in path is a mountpoint rather than the dentry
+ *  alone.
+ */
+bool path_is_mountpoint(const struct path *path)
+{
+       unsigned seq;
+       bool res;
+
+       if (!d_mountpoint(path->dentry))
+               return false;
+
+       rcu_read_lock();
+       do {
+               seq = read_seqbegin(&mount_lock);
+               res = __path_is_mountpoint(path);
+       } while (read_seqretry(&mount_lock, seq));
+       rcu_read_unlock();
+
+       return res;
+}
+EXPORT_SYMBOL(path_is_mountpoint);
+
 struct vfsmount *mnt_clone_internal(const struct path *path)
 {
        struct mount *p;
@@ -1568,11 +1619,11 @@ void __detach_mounts(struct dentry *dentry)
        struct mount *mnt;
 
        namespace_lock();
+       lock_mount_hash();
        mp = lookup_mountpoint(dentry);
        if (IS_ERR_OR_NULL(mp))
                goto out_unlock;
 
-       lock_mount_hash();
        event++;
        while (!hlist_empty(&mp->m_list)) {
                mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
@@ -1582,9 +1633,9 @@ void __detach_mounts(struct dentry *dentry)
                }
                else umount_tree(mnt, UMOUNT_CONNECTED);
        }
-       unlock_mount_hash();
        put_mountpoint(mp);
 out_unlock:
+       unlock_mount_hash();
        namespace_unlock();
 }
 
@@ -1799,9 +1850,7 @@ struct vfsmount *clone_private_mount(const struct path *path)
        if (IS_MNT_UNBINDABLE(old_mnt))
                return ERR_PTR(-EINVAL);
 
-       down_read(&namespace_sem);
        new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
-       up_read(&namespace_sem);
        if (IS_ERR(new_mnt))
                return ERR_CAST(new_mnt);
 
@@ -2013,9 +2062,7 @@ retry:
        namespace_lock();
        mnt = lookup_mnt(path);
        if (likely(!mnt)) {
-               struct mountpoint *mp = lookup_mountpoint(dentry);
-               if (!mp)
-                       mp = new_mountpoint(dentry);
+               struct mountpoint *mp = get_mountpoint(dentry);
                if (IS_ERR(mp)) {
                        namespace_unlock();
                        inode_unlock(dentry->d_inode);
@@ -2034,7 +2081,11 @@ retry:
 static void unlock_mount(struct mountpoint *where)
 {
        struct dentry *dentry = where->m_dentry;
+
+       read_seqlock_excl(&mount_lock);
        put_mountpoint(where);
+       read_sequnlock_excl(&mount_lock);
+
        namespace_unlock();
        inode_unlock(dentry->d_inode);
 }
@@ -3110,9 +3161,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        /* A moved mount should not expire automatically */
        list_del_init(&new_mnt->mnt_expire);
+       put_mountpoint(root_mp);
        unlock_mount_hash();
        chroot_fs_refs(&root, &new);
-       put_mountpoint(root_mp);
        error = 0;
 out4:
        unlock_mount(old_mp);