[Cluster-devel] [GFS2 PATCH 11/15] gfs2: reduce redundant code in gfs2_trans_add_*

[Bob Peterson <rpeterso@redhat.com>]

Before this patch, functions gfs2_trans_add_data and gfs2_trans_add_meta
did similar checks to see if the buffer_head had an existing bd element,
and if not, assigned one, temporarily dropping locks to allow for better
simultaneous operations. These checks were identical except that the
meta version held the page lock after unlocking the log_lock and buffer
lock.

This patch consolidates the similar code into the helper function,
gfs2_alloc_bufdata, for consistency and to eliminate code redundancy.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/trans.c | 46 ++++++++++++++++++++--------------------------
 1 file changed, 20 insertions(+), 26 deletions(-)

diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 63fec11ef2ce..4f70d381fd67 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -163,8 +163,20 @@ void gfs2_trans_end(struct gfs2_sbd *sdp)
 static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
 					       struct buffer_head *bh)
 {
+	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 	struct gfs2_bufdata *bd;
 
+	bd = bh->b_private;
+	if (bd)
+		goto out_check_gl;
+
+	gfs2_log_unlock(sdp);
+	unlock_buffer(bh);
+	lock_page(bh->b_page);
+	bd = bh->b_private;
+	if (bd)
+		goto out_noalloc;
+
 	bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
 	bd->bd_bh = bh;
 	bd->bd_gl = gl;
@@ -172,6 +184,12 @@ static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
 	INIT_LIST_HEAD(&bd->bd_ail_st_list);
 	INIT_LIST_HEAD(&bd->bd_ail_gl_list);
 	bh->b_private = bd;
+out_noalloc:
+	unlock_page(bh->b_page);
+	lock_buffer(bh);
+	gfs2_log_lock(sdp);
+out_check_gl:
+	gfs2_assert(sdp, bd->bd_gl == gl);
 	return bd;
 }
 
@@ -201,18 +219,7 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
 		goto out;
 	}
 	gfs2_log_lock(sdp);
-	bd = bh->b_private;
-	if (bd == NULL) {
-		gfs2_log_unlock(sdp);
-		unlock_buffer(bh);
-		if (bh->b_private == NULL)
-			bd = gfs2_alloc_bufdata(gl, bh);
-		else
-			bd = bh->b_private;
-		lock_buffer(bh);
-		gfs2_log_lock(sdp);
-	}
-	gfs2_assert(sdp, bd->bd_gl == gl);
+	bd = gfs2_alloc_bufdata(gl, bh);
 	set_bit(TR_TOUCHED, &tr->tr_flags);
 	if (list_empty(&bd->bd_list)) {
 		set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
@@ -241,20 +248,7 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
 		goto out;
 	}
 	gfs2_log_lock(sdp);
-	bd = bh->b_private;
-	if (bd == NULL) {
-		gfs2_log_unlock(sdp);
-		unlock_buffer(bh);
-		lock_page(bh->b_page);
-		if (bh->b_private == NULL)
-			bd = gfs2_alloc_bufdata(gl, bh);
-		else
-			bd = bh->b_private;
-		unlock_page(bh->b_page);
-		lock_buffer(bh);
-		gfs2_log_lock(sdp);
-	}
-	gfs2_assert(sdp, bd->bd_gl == gl);
+	bd = gfs2_alloc_bufdata(gl, bh);
 	set_bit(TR_TOUCHED, &tr->tr_flags);
 	if (!list_empty(&bd->bd_list))
 		goto out_unlock;
-- 
2.31.1