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>

diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 483c5a7e16d42568f41ff6516a521e92014b6966..affef3c066e098621a244027a08add5902f6ca56 100644 (file)
--- 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);
 }