gfs2: make gfs2_glock.gl_owner_pid be a struct pid *

The gl_owner_pid field is used to get the lock owning task by its pid, so make
it in a proper manner, i.e.  by using the struct pid pointer and pid_task()
function.

The pid_task() becomes exported for the gfs2 module.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 14 insertions, 8 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 82471c82f024..7175a4d06435 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -334,7 +334,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
         gl->gl_state = LM_ST_UNLOCKED;
         gl->gl_demote_state = LM_ST_EXCLUSIVE;
         gl->gl_hash = hash;
-        gl->gl_owner_pid = 0;
+        gl->gl_owner_pid = NULL;
         gl->gl_ip = 0;
         gl->gl_ops = glops;
         gl->gl_req_gh = NULL;
@@ -632,7 +632,7 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl)
                 wait_on_holder(&gh);
                 gfs2_holder_uninit(&gh);
         } else {
-                gl->gl_owner_pid = current->pid;
+                gl->gl_owner_pid = get_pid(task_pid(current));
                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
                 spin_unlock(&gl->gl_spin);
         }
@@ -653,7 +653,7 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
                 acquired = 0;
         } else {
-                gl->gl_owner_pid = current->pid;
+                gl->gl_owner_pid = get_pid(task_pid(current));
                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
         }
         spin_unlock(&gl->gl_spin);
@@ -669,12 +669,17 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
 
 static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
 {
+        struct pid *pid;
+
         spin_lock(&gl->gl_spin);
         clear_bit(GLF_LOCK, &gl->gl_flags);
-        gl->gl_owner_pid = 0;
+        pid = gl->gl_owner_pid;
+        gl->gl_owner_pid = NULL;
         gl->gl_ip = 0;
         run_queue(gl);
         spin_unlock(&gl->gl_spin);
+
+        put_pid(pid);
 }
 
 /**
@@ -1881,13 +1886,13 @@ static int dump_glock(struct glock_iter *gi, struct gfs2_glock *gl)
         print_dbg(gi, "  gl_ref = %d\n", atomic_read(&gl->gl_ref));
         print_dbg(gi, "  gl_state = %u\n", gl->gl_state);
         if (gl->gl_owner_pid) {
-                gl_owner = find_task_by_pid(gl->gl_owner_pid);
+                gl_owner = pid_task(gl->gl_owner_pid, PIDTYPE_PID);
                 if (gl_owner)
                         print_dbg(gi, "  gl_owner = pid %d (%s)\n",
-                                  gl->gl_owner_pid, gl_owner->comm);
+                                  pid_nr(gl->gl_owner_pid), gl_owner->comm);
                 else
                         print_dbg(gi, "  gl_owner = %d (ended)\n",
-                                  gl->gl_owner_pid);
+                                  pid_nr(gl->gl_owner_pid));
         } else
                 print_dbg(gi, "  gl_owner = -1\n");
         print_dbg(gi, "  gl_ip = %lu\n", gl->gl_ip);
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 4b724e772602..525dcae352d6 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -182,7 +182,7 @@ 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 */
-        pid_t gl_owner_pid;
+        struct pid *gl_owner_pid;
         unsigned long gl_ip;
         struct list_head gl_holders;
         struct list_head gl_waiters1;   /* HIF_MUTEX */
diff --git a/kernel/pid.c b/kernel/pid.c
index f815455431bf..3b30bccdfcdc 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -368,6 +368,7 @@ struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
         }
         return result;
 }
+EXPORT_SYMBOL(pid_task);
 
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.