[GFS2] Clean up gfs2_trans_add_revoke()

The following alters gfs2_trans_add_revoke() to take a struct
gfs2_bufdata as an argument. This eliminates the memory allocation which
was previously required by making use of the already existing struct
gfs2_bufdata. It makes some sanity checks to ensure that the
gfs2_bufdata has been removed from all the lists before its recycled as
a revoke structure. This saves one memory allocation and one free per
revoke structure.

Also as a result, and to simplify the locking, since there is no longer
any blocking code in gfs2_trans_add_revoke() we must hold the log lock
whenever this function is called. This reduces the amount of times we
take and unlock the log lock.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glops.c

@@ -41,7 +41,6 @@ static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
 	struct list_head *head = &gl->gl_ail_list;
 	struct gfs2_bufdata *bd;
 	struct buffer_head *bh;
-	u64 blkno;
 	int error;
 
 	blocks = atomic_read(&gl->gl_ail_count);
@@ -57,15 +56,12 @@ static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
 		bd = list_entry(head->next, struct gfs2_bufdata,
 				bd_ail_gl_list);
 		bh = bd->bd_bh;
-		blkno = bh->b_blocknr;
-		gfs2_assert_withdraw(sdp, !buffer_busy(bh));
-
 		gfs2_remove_from_ail(NULL, bd);
-		gfs2_log_unlock(sdp);
-
-		gfs2_trans_add_revoke(sdp, blkno);
-
-		gfs2_log_lock(sdp);
+		bd->bd_bh = NULL;
+		bh->b_private = NULL;
+		bd->bd_blkno = bh->b_blocknr;
+		gfs2_assert_withdraw(sdp, !buffer_busy(bh));
+		gfs2_trans_add_revoke(sdp, bd);
 	}
 	gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
 	gfs2_log_unlock(sdp);

fs/gfs2/log.c

@@ -71,8 +71,8 @@ unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
 void gfs2_remove_from_ail(struct address_space *mapping, struct gfs2_bufdata *bd)
 {
 	bd->bd_ail = NULL;
-	list_del(&bd->bd_ail_st_list);
-	list_del(&bd->bd_ail_gl_list);
+	list_del_init(&bd->bd_ail_st_list);
+	list_del_init(&bd->bd_ail_gl_list);
 	atomic_dec(&bd->bd_gl->gl_ail_count);
 	if (mapping)
 		gfs2_meta_cache_flush(GFS2_I(mapping->host));

fs/gfs2/lops.c

@@ -343,11 +343,8 @@ static void revoke_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 	tr = current->journal_info;
 	tr->tr_touched = 1;
 	tr->tr_num_revoke++;
-
-	gfs2_log_lock(sdp);
 	sdp->sd_log_num_revoke++;
 	list_add(&le->le_list, &sdp->sd_log_le_revoke);
-	gfs2_log_unlock(sdp);
 }
 
 static void revoke_lo_before_commit(struct gfs2_sbd *sdp)

fs/gfs2/meta_io.c

@@ -313,42 +313,31 @@ void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)
 	while (blen) {
 		bh = getbuf(ip->i_gl, bstart, NO_CREATE);
 		if (bh) {
-			struct gfs2_bufdata *bd = bh->b_private;
+			struct gfs2_bufdata *bd;
 
+			lock_buffer(bh);
+			gfs2_log_lock(sdp);
+			bd = bh->b_private;
 			if (test_clear_buffer_pinned(bh)) {
 				struct gfs2_trans *tr = current->journal_info;
-				struct gfs2_inode *bh_ip =
-					GFS2_I(bh->b_page->mapping->host);
-
-				gfs2_log_lock(sdp);
 				list_del_init(&bd->bd_le.le_list);
 				gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
 				sdp->sd_log_num_buf--;
-				gfs2_log_unlock(sdp);
-				if (bh_ip->i_inode.i_private != NULL)
-					tr->tr_num_databuf_rm++;
-				else
-					tr->tr_num_buf_rm++;
+				tr->tr_num_buf_rm++;
 				brelse(bh);
 			}
 			if (bd) {
-				gfs2_log_lock(sdp);
 				if (bd->bd_ail) {
-					u64 blkno = bh->b_blocknr;
-					bd->bd_ail = NULL;
-					list_del(&bd->bd_ail_st_list);
-					list_del(&bd->bd_ail_gl_list);
-					atomic_dec(&bd->bd_gl->gl_ail_count);
-					brelse(bh);
-					gfs2_log_unlock(sdp);
-					gfs2_trans_add_revoke(sdp, blkno);
-				} else
-					gfs2_log_unlock(sdp);
+					gfs2_remove_from_ail(NULL, bd);
+					bh->b_private = NULL;
+					bd->bd_bh = NULL;
+					bd->bd_blkno = bh->b_blocknr;
+					gfs2_trans_add_revoke(sdp, bd);
+				}
 			}
-
-			lock_buffer(bh);
 			clear_buffer_dirty(bh);
 			clear_buffer_uptodate(bh);
+			gfs2_log_unlock(sdp);
 			unlock_buffer(bh);
 
 			brelse(bh);

fs/gfs2/trans.c

@@ -142,12 +142,12 @@ void gfs2_trans_add_bh(struct gfs2_glock *gl, struct buffer_head *bh, int meta)
 	lops_add(sdp, &bd->bd_le);
 }
 
-void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, u64 blkno)
+void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
 {
-	struct gfs2_bufdata *bd = kmem_cache_alloc(gfs2_bufdata_cachep,
-					  GFP_NOFS | __GFP_NOFAIL);
+	BUG_ON(!list_empty(&bd->bd_le.le_list));
+	BUG_ON(!list_empty(&bd->bd_ail_st_list));
+	BUG_ON(!list_empty(&bd->bd_ail_gl_list));
 	lops_init_le(&bd->bd_le, &gfs2_revoke_lops);
-	bd->bd_blkno = blkno;
 	lops_add(sdp, &bd->bd_le);
 }
 
@@ -160,7 +160,7 @@ void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno)
 
 	list_for_each_entry(bd, &sdp->sd_log_le_revoke, bd_le.le_list) {
 		if (bd->bd_blkno == blkno) {
-			list_del(&bd->bd_le.le_list);
+			list_del_init(&bd->bd_le.le_list);
 			gfs2_assert_withdraw(sdp, sdp->sd_log_num_revoke);
 			sdp->sd_log_num_revoke--;
 			found = 1;

fs/gfs2/trans.h

@@ -32,7 +32,7 @@ void gfs2_trans_end(struct gfs2_sbd *sdp);
 
 void gfs2_trans_add_gl(struct gfs2_glock *gl);
 void gfs2_trans_add_bh(struct gfs2_glock *gl, struct buffer_head *bh, int meta);
-void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, u64 blkno);
+void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd);
 void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno);
 void gfs2_trans_add_rg(struct gfs2_rgrpd *rgd);