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: (52 commits)
  init: Open /dev/console from rootfs
  mqueue: fix typo "failues" -> "failures"
  mqueue: only set error codes if they are really necessary
  mqueue: simplify do_open() error handling
  mqueue: apply mathematics distributivity on mq_bytes calculation
  mqueue: remove unneeded info->messages initialization
  mqueue: fix mq_open() file descriptor leak on user-space processes
  fix race in d_splice_alias()
  set S_DEAD on unlink() and non-directory rename() victims
  vfs: add NOFOLLOW flag to umount(2)
  get rid of ->mnt_parent in tomoyo/realpath
  hppfs can use existing proc_mnt, no need for do_kern_mount() in there
  Mirror MS_KERNMOUNT in ->mnt_flags
  get rid of useless vfsmount_lock use in put_mnt_ns()
  Take vfsmount_lock to fs/internal.h
  get rid of insanity with namespace roots in tomoyo
  take check for new events in namespace (guts of mounts_poll()) to namespace.c
  Don't mess with generic_permission() under ->d_lock in hpfs
  sanitize const/signedness for udf
  nilfs: sanitize const/signedness in dealing with ->d_name.name
  ...

Fix up fairly trivial (famous last words...) conflicts in
drivers/infiniband/core/uverbs_main.c and security/tomoyo/realpath.c

1 files changed, 15 insertions, 1 deletions

diff --git a/Documentation/filesystems/sharedsubtree.txt b/Documentation/filesystems/sharedsubtree.txt
index 23a181074f9..fc0e39af43c 100644
--- a/Documentation/filesystems/sharedsubtree.txt
+++ b/Documentation/filesystems/sharedsubtree.txt
@@ -837,6 +837,9 @@ replicas continue to be exactly same.
 	 individual lists does not affect propagation or the way propagation
 	 tree is modified by operations.
 
+	All vfsmounts in a peer group have the same ->mnt_master.  If it is
+	non-NULL, they form a contiguous (ordered) segment of slave list.
+
 	A example propagation tree looks as shown in the figure below.
 	[ NOTE: Though it looks like a forest, if we consider all the shared
 	mounts as a conceptual entity called 'pnode', it becomes a tree]
@@ -874,8 +877,19 @@ replicas continue to be exactly same.
 
 	NOTE: The propagation tree is orthogonal to the mount tree.
 
+8B Locking:
+
+	->mnt_share, ->mnt_slave, ->mnt_slave_list, ->mnt_master are protected
+	by namespace_sem (exclusive for modifications, shared for reading).
+
+	Normally we have ->mnt_flags modifications serialized by vfsmount_lock.
+	There are two exceptions: do_add_mount() and clone_mnt().
+	The former modifies a vfsmount that has not been visible in any shared
+	data structures yet.
+	The latter holds namespace_sem and the only references to vfsmount
+	are in lists that can't be traversed without namespace_sem.
 
-8B Algorithm:
+8C Algorithm:
 
 	The crux of the implementation resides in rbind/move operation.