GFS2: Reduce contention on gfs2_log_lock

This patch modifies functions gfs2_trans_add_meta and _data so that
they check whether the buffer_head is already in a transaction,
and if so, avoid taking the gfs2_log_lock.

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

1 files changed, 11 insertions, 2 deletions

diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 483c5a7e16d4..affef3c066e0 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -170,6 +170,10 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
         }
 
         lock_buffer(bh);
+        if (buffer_pinned(bh)) {
+                set_bit(TR_TOUCHED, &tr->tr_flags);
+                goto out;
+        }
         gfs2_log_lock(sdp);
         bd = bh->b_private;
         if (bd == NULL) {
@@ -192,6 +196,7 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
                 list_add_tail(&bd->bd_list, &tr->tr_databuf);
         }
         gfs2_log_unlock(sdp);
+out:
         unlock_buffer(bh);
 }
 
@@ -201,10 +206,14 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
         struct gfs2_bufdata *bd;
         struct gfs2_meta_header *mh;
-        struct gfs2_trans *tr;
+        struct gfs2_trans *tr = current->journal_info;
         enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
 
         lock_buffer(bh);
+        if (buffer_pinned(bh)) {
+                set_bit(TR_TOUCHED, &tr->tr_flags);
+                goto out;
+        }
         gfs2_log_lock(sdp);
         bd = bh->b_private;
         if (bd == NULL) {
@@ -220,7 +229,6 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
                 gfs2_log_lock(sdp);
         }
         gfs2_assert(sdp, bd->bd_gl == gl);
-        tr = current->journal_info;
         set_bit(TR_TOUCHED, &tr->tr_flags);
         if (!list_empty(&bd->bd_list))
                 goto out_unlock;
@@ -243,6 +251,7 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
         tr->tr_num_buf_new++;
 out_unlock:
         gfs2_log_unlock(sdp);
+out:
         unlock_buffer(bh);
 }