[GFS2] Add list empty test to databuf_lo_add

Heinz had spotted that I'd forgotten to test in databuf_lo_add()
that the data buffer in question hadn't already been added to
the list. This was causing an infinite loop later on in the
"before commit" routine.

This means that GFS2 is now ready to be tested by everybody.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/lops.c

@@ -291,7 +291,7 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
 
 	while (!list_empty(head)) {
 		rv = list_entry(head->next, struct gfs2_revoke, rv_le.le_list);
-		list_del(&rv->rv_le.le_list);
+		list_del_init(&rv->rv_le.le_list);
 		sdp->sd_log_num_revoke--;
 
 		if (offset + sizeof(uint64_t) > sdp->sd_sb.sb_bsize) {
@@ -460,10 +460,12 @@ static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 		gfs2_pin(sdp, bd->bd_bh);
 	}
 	gfs2_log_lock(sdp);
-	if (ip->i_di.di_flags & GFS2_DIF_JDATA)
-		sdp->sd_log_num_jdata++;
-	sdp->sd_log_num_databuf++;
-	list_add(&le->le_list, &sdp->sd_log_le_databuf);
+	if (!list_empty(&le->le_list)) {
+		if (ip->i_di.di_flags & GFS2_DIF_JDATA)
+			sdp->sd_log_num_jdata++;
+		sdp->sd_log_num_databuf++;
+		list_add(&le->le_list, &sdp->sd_log_le_databuf);
+	}
 	gfs2_log_unlock(sdp);
 }
 
@@ -503,25 +505,21 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 	unsigned int total_jdata = sdp->sd_log_num_jdata;
 	unsigned int num, n;
 	__be64 *ptr = NULL;
-	unsigned i;
 
 	offset += (2*sizeof(__be64) - 1);
 	offset &= ~(2*sizeof(__be64) - 1);
 	limit = (sdp->sd_sb.sb_bsize - offset)/sizeof(__be64);
 
-	/* printk(KERN_INFO "totals: jdata=%u dbuf=%u\n", total_jdata, total_dbuf); */
 	/*
 	 * Start writing ordered buffers, write journaled buffers
 	 * into the log along with a header
 	 */
 	gfs2_log_lock(sdp);
-	/* printk(KERN_INFO "locked in lops databuf_before_commit\n"); */
 	bd2 = bd1 = list_prepare_entry(bd1, &sdp->sd_log_le_databuf, bd_le.le_list);
 	while(total_dbuf) {
 		num = total_jdata;
 		if (num > limit)
 			num = limit;
-		/* printk(KERN_INFO "total_dbuf=%u num=%u\n", total_dbuf, num); */
 		n = 0;
 		i = 0;
 		list_for_each_entry_safe_continue(bd1, bdt, &sdp->sd_log_le_databuf, bd_le.le_list) {
@@ -542,21 +540,12 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 						gfs2_log_lock(sdp);
 					}
 					brelse(bd1->bd_bh);
-					/* printk(KERN_INFO "db write %p\n", bd1); */
-					if (++i > 100000) {
-						printk(KERN_INFO "looping bd1=%p bdt=%p eol=%p started=%p\n", bd1, bdt, &sdp->sd_log_le_databuf, &started);
-						dump_stack();
-						BUG();
-					}
 					continue;
 				}
-				/* printk(KERN_INFO "db skip\n"); */
 				continue;
 			} else if (bd1->bd_bh) { /* A journaled buffer */
 				int magic;
 				gfs2_log_unlock(sdp);
-				printk(KERN_INFO "journaled buffer %p\n", bd1->bd_bh);
-				printk(KERN_INFO "%lu %u %p %p\n", bd1->bd_bh->b_blocknr, bd1->bd_bh->b_size, bd1->bd_bh->b_data, bd1->bd_bh->b_page);  
 				if (!bh) {
 					bh = gfs2_log_get_buf(sdp);
 					ld = (struct gfs2_log_descriptor *)bh->b_data;
@@ -570,12 +559,9 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 					ld->ld_data2 = cpu_to_be32(0);
 					memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
 				}
-				/* printk(KERN_INFO "check_magic\n"); */
 				magic = gfs2_check_magic(bd1->bd_bh);
-				/* printk(KERN_INFO "write data\n"); */
 				*ptr++ = cpu_to_be64(bd1->bd_bh->b_blocknr);
 				*ptr++ = cpu_to_be64((__u64)magic);
-				/* printk(KERN_INFO "mark escaped or not\n"); */
 				clear_buffer_escaped(bd1->bd_bh);
 				if (unlikely(magic != 0))
 					set_buffer_escaped(bd1->bd_bh);
@@ -591,7 +577,6 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 			bh = NULL;
 		}
 		n = 0;
-		/* printk(KERN_INFO "totals2: jdata=%u dbuf=%u\n", total_jdata, total_dbuf); */
 		gfs2_log_lock(sdp);
 		list_for_each_entry_continue(bd2, &sdp->sd_log_le_databuf, bd_le.le_list) {
 			if (!bd2->bd_bh)
@@ -621,14 +606,13 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 	}
 	gfs2_log_unlock(sdp);
 
-	/* printk(KERN_INFO "wait on ordered data buffers\n"); */
 	/* Wait on all ordered buffers */
 	while (!list_empty(&started)) {
+		gfs2_log_lock(sdp);
 		bd1 = list_entry(started.next, struct gfs2_bufdata, bd_le.le_list);
 		list_del(&bd1->bd_le.le_list);
 		sdp->sd_log_num_databuf--;
 
-		gfs2_log_lock(sdp);
 		bh = bd1->bd_bh;
 		if (bh) {
 			set_v2bd(bh, NULL);
@@ -641,7 +625,6 @@ static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
 		kfree(bd1);
 	}
 
-	/* printk(KERN_INFO "sd_log_num_databuf %u sd_log_num_jdata %u\n", sdp->sd_log_num_databuf, sdp->sd_log_num_jdata); */
 	/* We've removed all the ordered write bufs here, so only jdata left */
 	gfs2_assert_warn(sdp, sdp->sd_log_num_databuf == sdp->sd_log_num_jdata);
 }