[GFS2] Red Hat bz 228540: owner references

In Testing the previously posted and accepted patch for
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=228540
I uncovered some gfs2 badness.  It turns out that the current
gfs2 code saves off a process pointer when glocks is taken
in both the glock and glock holder structures.  Those
structures will persist in memory long after the process has
ended; pointers to poisoned memory.

This problem isn't caused by the 228540 fix; the new capability
introduced by the fix just uncovered the problem.

I wrote this patch that avoids saving process pointers
and instead saves off the process pid.  Rather than
referencing the bad pointers, it now does process lookups.
There is special code that makes the output nicer for
printing holder information for processes that have ended.

This patch also adds a stub for the new "sprint_symbol"
function that exists in Andrew Morton's -mm patch set, but
won't go into the base kernel until 2.6.22, since it adds
functionality but doesn't fix a bug.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 9c125823d760..fdf04705906f 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -127,7 +127,7 @@ struct gfs2_holder {
         struct list_head gh_list;
 
         struct gfs2_glock *gh_gl;
-        struct task_struct *gh_owner;
+        pid_t gh_owner_pid;
         unsigned int gh_state;
         unsigned gh_flags;
 
@@ -155,7 +155,7 @@ struct gfs2_glock {
         unsigned int gl_hash;
         unsigned int gl_demote_state; /* state requested by remote node */
         unsigned long gl_demote_time; /* time of first demote request */
-        struct task_struct *gl_owner;
+        pid_t gl_owner_pid;
         unsigned long gl_ip;
         struct list_head gl_holders;
         struct list_head gl_waiters1;   /* HIF_MUTEX */