[GFS2] Use mutices rather than semaphores

As well as a number of minor bug fixes, this patch changes GFS
to use mutices rather than semaphores. This results in better
information in case there are any locking problems.

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

1 files changed, 19 insertions, 35 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 49190a29dd4f..e6acb41332e7 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -23,29 +23,16 @@
 
 #define PULL 1
 
-static inline int is_done(struct gfs2_sbd *sdp, atomic_t *a)
-{
-        int done;
-        gfs2_log_lock(sdp);
-        done = atomic_read(a) ? 0 : 1;
-        gfs2_log_unlock(sdp);
-        return done;
-}
-
 static void do_lock_wait(struct gfs2_sbd *sdp, wait_queue_head_t *wq,
                          atomic_t *a)
 {
-        gfs2_log_unlock(sdp);
-        wait_event(*wq, is_done(sdp, a));
-        gfs2_log_lock(sdp);
+        wait_event(*wq, atomic_read(a) ? 0 : 1);
 }
 
 static void lock_for_trans(struct gfs2_sbd *sdp)
 {
-        gfs2_log_lock(sdp);
         do_lock_wait(sdp, &sdp->sd_log_trans_wq, &sdp->sd_log_flush_count);
         atomic_inc(&sdp->sd_log_trans_count);
-        gfs2_log_unlock(sdp);
 }
 
 static void unlock_from_trans(struct gfs2_sbd *sdp)
@@ -55,15 +42,13 @@ static void unlock_from_trans(struct gfs2_sbd *sdp)
                 wake_up(&sdp->sd_log_flush_wq);
 }
 
-void gfs2_lock_for_flush(struct gfs2_sbd *sdp)
+static void gfs2_lock_for_flush(struct gfs2_sbd *sdp)
 {
-        gfs2_log_lock(sdp);
         atomic_inc(&sdp->sd_log_flush_count);
         do_lock_wait(sdp, &sdp->sd_log_flush_wq, &sdp->sd_log_trans_count);
-        gfs2_log_unlock(sdp);
 }
 
-void gfs2_unlock_from_flush(struct gfs2_sbd *sdp)
+static void gfs2_unlock_from_flush(struct gfs2_sbd *sdp)
 {
         gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_flush_count));
         if (atomic_dec_and_test(&sdp->sd_log_flush_count))
@@ -209,7 +194,6 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
 
         for (;;) {
                 gfs2_log_lock(sdp);
-
                 if (list_empty(&list)) {
                         list_add_tail(&list, &sdp->sd_log_blks_list);
                         while (sdp->sd_log_blks_list.next != &list) {
@@ -225,7 +209,6 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
                                 set_current_state(TASK_RUNNING);
                         }
                 }
-
                 /* Never give away the last block so we can
                    always pull the tail if we need to. */
                 if (sdp->sd_log_blks_free > blks) {
@@ -237,14 +220,12 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
                 }
 
                 gfs2_log_unlock(sdp);
-
                 gfs2_ail1_empty(sdp, 0);
                 gfs2_log_flush(sdp);
 
                 if (try++)
                         gfs2_ail1_start(sdp, 0);
         }
-
         lock_for_trans(sdp);
 
         return 0;
@@ -512,22 +493,26 @@ void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);
         INIT_LIST_HEAD(&ai->ai_ail1_list);
         INIT_LIST_HEAD(&ai->ai_ail2_list);
-
         gfs2_lock_for_flush(sdp);
-        down(&sdp->sd_log_flush_lock);
+
+        if (gl) {
+                gfs2_log_lock(sdp);
+                if (list_empty(&gl->gl_le.le_list)) {
+                        gfs2_log_unlock(sdp);
+                        gfs2_unlock_from_flush(sdp);
+                        kfree(ai);
+                        return;
+                }
+                gfs2_log_unlock(sdp);
+        }
+
+        mutex_lock(&sdp->sd_log_flush_lock);
 
         gfs2_assert_withdraw(sdp,
                         sdp->sd_log_num_buf == sdp->sd_log_commited_buf);
         gfs2_assert_withdraw(sdp,
                         sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);
 
-        if (gl && list_empty(&gl->gl_le.le_list)) {
-                up(&sdp->sd_log_flush_lock);
-                gfs2_unlock_from_flush(sdp);
-                kfree(ai);
-                return;
-        }
-
         sdp->sd_log_flush_head = sdp->sd_log_head;
         sdp->sd_log_flush_wrapped = 0;
         ai->ai_first = sdp->sd_log_flush_head;
@@ -538,7 +523,6 @@ void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle)
                 log_write_header(sdp, 0, PULL);
         lops_after_commit(sdp, ai);
-
         sdp->sd_log_head = sdp->sd_log_flush_head;
         if (sdp->sd_log_flush_wrapped)
                 sdp->sd_log_wraps++;
@@ -554,7 +538,7 @@ void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         }
         gfs2_log_unlock(sdp);
 
-        up(&sdp->sd_log_flush_lock);
+        mutex_unlock(&sdp->sd_log_flush_lock);
         sdp->sd_vfs->s_dirt = 0;
         gfs2_unlock_from_flush(sdp);
 
@@ -627,7 +611,7 @@ void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 
 void gfs2_log_shutdown(struct gfs2_sbd *sdp)
 {
-        down(&sdp->sd_log_flush_lock);
+        mutex_lock(&sdp->sd_log_flush_lock);
 
         gfs2_assert_withdraw(sdp, !atomic_read(&sdp->sd_log_trans_count));
         gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
@@ -654,6 +638,6 @@ void gfs2_log_shutdown(struct gfs2_sbd *sdp)
                 sdp->sd_log_wraps++;
         sdp->sd_log_tail = sdp->sd_log_head;
 
-        up(&sdp->sd_log_flush_lock);
+        mutex_unlock(&sdp->sd_log_flush_lock);
 }