KVM: x86: Save&restore interrupt shadow mask

[safe/jmp/linux-2.6] / Documentation / filesystems / sharedsubtree.txt

diff --git a/Documentation/filesystems/sharedsubtree.txt b/Documentation/filesystems/sharedsubtree.txt
index b2c1ee5..fc0e39a 100644 (file)
--- a/Documentation/filesystems/sharedsubtree.txt
+++ b/Documentation/filesystems/sharedsubtree.txt
@@ -4,7 +4,7 @@ Shared Subtrees
 Contents:
        1) Overview
        2) Features
-       3) smount command
+       3) Setting mount states
        4) Use-case
        5) Detailed semantics
        6) Quiz
@@ -135,10 +135,15 @@ replicas continue to be exactly same.
        Binding a unbindable mount is a invalid operation.
 
 
-3) smount command
+3) Setting mount states
 
-       Modern mount(8) command is aware of shared subtree features,
-       so use it instead of the 'smount' command. [source code removed]
+       The mount command (util-linux package) can be used to set mount
+       states:
+
+       mount --make-shared mountpoint
+       mount --make-slave mountpoint
+       mount --make-private mountpoint
+       mount --make-unbindable mountpoint
 
 
 4) Use cases
@@ -209,7 +214,7 @@ replicas continue to be exactly same.
                mount --rbind / /view/v3
                mount --rbind / /view/v4
 
-               and if /usr has a versioning filesystem mounted, than that
+               and if /usr has a versioning filesystem mounted, then that
                mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
                /view/v4/usr too
 
@@ -249,7 +254,7 @@ replicas continue to be exactly same.
 
                For example:
                        mount --make-shared /mnt
-                       mount --bin /mnt /tmp
+                       mount --bind /mnt /tmp
 
                The mount at /mnt and that at /tmp are both shared and belong
                to the same peer group. Anything mounted or unmounted under
@@ -832,6 +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]
@@ -869,8 +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.