ocfs2: Move /sys/o2cb to /sys/fs/o2cb

/sys/fs is where we really want file system specific sysfs objects.

Ocfs2-tools has been updated to look in /sys/fs/o2cb. We can maintain
backwards compatibility with old ocfs2-tools by using a sysfs symlink. After
some time (2 years), the symlink can be safely removed. This patch also adds
documentation to make it easier for people to figure out what /sys/fs/o2cb
is used for.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>

4 files changed, 40 insertions, 0 deletions

diff --git a/Documentation/ABI/obsolete/o2cb b/Documentation/ABI/obsolete/o2cb
new file mode 100644
index 00000000000..9c49d8e6c0c
--- /dev/null
+++ b/Documentation/ABI/obsolete/o2cb
@@ -0,0 +1,11 @@
+What:           /sys/o2cb symlink
+Date:           Dec 2005
+KernelVersion:  2.6.16
+Contact:        ocfs2-devel@oss.oracle.com
+Description:    This is a symlink: /sys/o2cb to /sys/fs/o2cb. The symlink will
+                be removed when new versions of ocfs2-tools which know to look
+                in /sys/fs/o2cb are sufficiently prevalent. Don't code new
+                software to look here, it should try /sys/fs/o2cb instead.
+                See Documentation/ABI/stable/o2cb for more information on usage.
+Users:          ocfs2-tools. It's sufficient to mail proposed changes to
+                ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/ABI/stable/o2cb b/Documentation/ABI/stable/o2cb
new file mode 100644
index 00000000000..5eb1545e0b8
--- /dev/null
+++ b/Documentation/ABI/stable/o2cb
@@ -0,0 +1,10 @@
+What:           /sys/fs/o2cb/ (was /sys/o2cb)
+Date:           Dec 2005
+KernelVersion:  2.6.16
+Contact:        ocfs2-devel@oss.oracle.com
+Description:    Ocfs2-tools looks at 'interface-revision' for versioning
+                information. Each logmask/ file controls a set of debug prints
+                and can be written into with the strings "allow", "deny", or
+                "off". Reading the file returns the current state.
+Users:          ocfs2-tools. It's sufficient to mail proposed changes to
+                ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index bf0e3df8e7a..4101f1f2d1e 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -318,3 +318,13 @@ Why:	Not used in-tree. The current out-of-tree users used it to
         code / infrastructure should be in the kernel and not in some
         out-of-tree driver.
 Who:    Thomas Gleixner <tglx@linutronix.de>
+
+---------------------------
+
+What:   /sys/o2cb symlink
+When:   January 2010
+Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
+        exists as a symlink for backwards compatibility for old versions of
+        ocfs2-tools. 2 years should be sufficient time to phase in new versions
+        which know to look in /sys/fs/o2cb.
+Who:    ocfs2-devel@oss.oracle.com
diff --git a/fs/ocfs2/cluster/sys.c b/fs/ocfs2/cluster/sys.c
index 0c095ce7723..98429fd6849 100644
--- a/fs/ocfs2/cluster/sys.c
+++ b/fs/ocfs2/cluster/sys.c
@@ -57,6 +57,7 @@ static struct kset *o2cb_kset;
 void o2cb_sys_shutdown(void)
 {
         mlog_sys_shutdown();
+        sysfs_remove_link(NULL, "o2cb");
         kset_unregister(o2cb_kset);
 }
 
@@ -68,6 +69,14 @@ int o2cb_sys_init(void)
         if (!o2cb_kset)
                 return -ENOMEM;
 
+        /*
+         * Create this symlink for backwards compatibility with old
+         * versions of ocfs2-tools which look for things in /sys/o2cb.
+         */
+        ret = sysfs_create_link(NULL, &o2cb_kset->kobj, "o2cb");
+        if (ret)
+                goto error;
+
         ret = sysfs_create_group(&o2cb_kset->kobj, &o2cb_attr_group);
         if (ret)
                 goto error;