Merge tag 'v3.16-rc5' into HEAD

Docbook creation was broken. We need to move after
v3.16-rc1-3-ga981296f048b in order to get commit
a981296f048b99b0d5bb4d87c732a6cfb35a1c66.

Linux 3.16-rc5

* tag 'v3.16-rc5': (985 commits)
  Linux 3.16-rc5
  clk: spear3xx: Set proper clock parent of uart1/2
  clk: spear3xx: Use proper control register offset
  parisc: drop unused defines and header includes
  parisc: fix fanotify_mark() syscall on 32bit compat kernel
  parisc: add serial ports of C8000/1GHz machine to hardware database
  ext4: fix potential null pointer dereference in ext4_free_inode
  ext4: fix a potential deadlock in __ext4_es_shrink()
  Documenation/laptops: rename and update hpfall.c
  DocBook: fix various typos
  DocBook: fix mtdnand typos
  scripts/kernel-doc: handle object-like macros
  Documentation/Changes: clean up mcelog paragraph
  ARM: at91: at91sam9x5: add clocks for usb device
  phy: omap-usb2: Balance pm_runtime_enable() on probe failure and remove
  phy: core: Fix error path in phy_create()
  drivers: phy: phy-samsung-usb2.c: Add missing MODULE_DEVICE_TABLE
  phy: omap-usb2: fix devm_ioremap_resource error detection code
  phy: sun4i: depend on RESET_CONTROLLER
  USB: serial: ftdi_sio: Add Infineon Triboard
  ...

1 files changed, 30 insertions, 0 deletions

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index d171b98a6cdd..f973ae9b05f1 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -211,6 +211,36 @@ void kernfs_kill_sb(struct super_block *sb)
 	kernfs_put(root_kn);
 }
 
+/**
+ * kernfs_pin_sb: try to pin the superblock associated with a kernfs_root
+ * @kernfs_root: the kernfs_root in question
+ * @ns: the namespace tag
+ *
+ * Pin the superblock so the superblock won't be destroyed in subsequent
+ * operations.  This can be used to block ->kill_sb() which may be useful
+ * for kernfs users which dynamically manage superblocks.
+ *
+ * Returns NULL if there's no superblock associated to this kernfs_root, or
+ * -EINVAL if the superblock is being freed.
+ */
+struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns)
+{
+	struct kernfs_super_info *info;
+	struct super_block *sb = NULL;
+
+	mutex_lock(&kernfs_mutex);
+	list_for_each_entry(info, &root->supers, node) {
+		if (info->ns == ns) {
+			sb = info->sb;
+			if (!atomic_inc_not_zero(&info->sb->s_active))
+				sb = ERR_PTR(-EINVAL);
+			break;
+		}
+	}
+	mutex_unlock(&kernfs_mutex);
+	return sb;
+}
+
 void __init kernfs_init(void)
 {
 	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",