GFS2: Alter point of entry to glock lru list for glocks with an address_space

Rather than allowing the glocks to be scheduled for possible
reclaim as soon as they have exited the journal, this patch
delays their entry to the list until the glocks in question
are no longer in use.

This means that we will rely on the vm for writeback of all
dirty data and metadata from now on. When glocks are added
to the lru list they should be freeable much faster since all
the I/O required to free them should have already been completed.

This should lead to much better I/O patterns under low memory
conditions.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glock.c

@@ -160,6 +160,19 @@ static int demote_ok(const struct gfs2_glock *gl)
 }
 
 
+void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
+{
+	spin_lock(&lru_lock);
+
+	if (!list_empty(&gl->gl_lru))
+		list_del_init(&gl->gl_lru);
+	else
+		atomic_inc(&lru_count);
+
+	list_add_tail(&gl->gl_lru, &lru_list);
+	spin_unlock(&lru_lock);
+}
+
 /**
  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
  * @gl: the glock
@@ -170,24 +183,8 @@ static int demote_ok(const struct gfs2_glock *gl)
 
 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 {
-	if (demote_ok(gl)) {
-		spin_lock(&lru_lock);
-
-		if (!list_empty(&gl->gl_lru))
-			list_del_init(&gl->gl_lru);
-		else
-			atomic_inc(&lru_count);
-
-		list_add_tail(&gl->gl_lru, &lru_list);
-		spin_unlock(&lru_lock);
-	}
-}
-
-void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
-{
-	spin_lock(&gl->gl_spin);
-	__gfs2_glock_schedule_for_reclaim(gl);
-	spin_unlock(&gl->gl_spin);
+	if (demote_ok(gl))
+		gfs2_glock_add_to_lru(gl);
 }
 
 /**

fs/gfs2/glock.h

@@ -225,11 +225,10 @@ static inline int gfs2_glock_nq_init(struct gfs2_glock *gl,
 
 extern void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state);
 extern void gfs2_glock_complete(struct gfs2_glock *gl, int ret);
-extern void gfs2_reclaim_glock(struct gfs2_sbd *sdp);
 extern void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
 extern void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
 extern void gfs2_glock_thaw(struct gfs2_sbd *sdp);
-extern void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl);
+extern void gfs2_glock_add_to_lru(struct gfs2_glock *gl);
 extern void gfs2_glock_free(struct gfs2_glock *gl);
 
 extern int __init gfs2_glock_init(void);

fs/gfs2/lops.c

@@ -40,7 +40,7 @@ static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
 {
 	struct gfs2_bufdata *bd;
 
-	gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));
+	BUG_ON(!current->journal_info);
 
 	clear_buffer_dirty(bh);
 	if (test_set_buffer_pinned(bh))
@@ -65,6 +65,7 @@ static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
  * @sdp: the filesystem the buffer belongs to
  * @bh: The buffer to unpin
  * @ai:
+ * @flags: The inode dirty flags
  *
  */
 
@@ -73,10 +74,8 @@ static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
 {
 	struct gfs2_bufdata *bd = bh->b_private;
 
-	gfs2_assert_withdraw(sdp, buffer_uptodate(bh));
-
-	if (!buffer_pinned(bh))
-		gfs2_assert_withdraw(sdp, 0);
+	BUG_ON(!buffer_uptodate(bh));
+	BUG_ON(!buffer_pinned(bh));
 
 	lock_buffer(bh);
 	mark_buffer_dirty(bh);
@@ -95,8 +94,7 @@ static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
 	list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
 	spin_unlock(&sdp->sd_ail_lock);
 
-	if (test_and_clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags))
-		gfs2_glock_schedule_for_reclaim(bd->bd_gl);
+	clear_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
 	trace_gfs2_pin(bd, 0);
 	unlock_buffer(bh);
 	atomic_dec(&sdp->sd_log_pinned);

fs/gfs2/rgrp.c

@@ -392,6 +392,7 @@ static void clear_rgrpdi(struct gfs2_sbd *sdp)
 
 		if (gl) {
 			gl->gl_object = NULL;
+			gfs2_glock_add_to_lru(gl);
 			gfs2_glock_put(gl);
 		}
 

fs/gfs2/super.c

@@ -1401,6 +1401,7 @@ static void gfs2_evict_inode(struct inode *inode)
 	end_writeback(inode);
 
 	ip->i_gl->gl_object = NULL;
+	gfs2_glock_add_to_lru(ip->i_gl);
 	gfs2_glock_put(ip->i_gl);
 	ip->i_gl = NULL;
 	if (ip->i_iopen_gh.gh_gl) {