From 96feccc47d23423d84ebfa6c24d88875d6d0d3c8 Mon Sep 17 00:00:00 2001
From: Krzysztof Mazur <krzysiek@podlesie.net>
Date: Wed, 18 May 2011 20:34:09 +0200
Subject: [PATCH 34/84] lsbd: fix online logical resizing

---
 drivers/block/lsbd.c | 73 ++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 56 insertions(+), 17 deletions(-)

diff --git a/drivers/block/lsbd.c b/drivers/block/lsbd.c
index b666bfa..448a88d 100644
--- a/drivers/block/lsbd.c
+++ b/drivers/block/lsbd.c
@@ -947,23 +947,48 @@ static int lsbd_load_params(struct lsbd *p)
  *
  * TODO: Clean write queue.
  */
-static void lsbd_stop(struct lsbd *p, struct block_device *bdev)
+static void lsbd_stop(struct lsbd *p)
 {
 	struct completion event;
-	kdev_t dev = to_kdev_t(bdev->bd_dev);
+	unsigned int i;
 
 	lsbd_info(p, "stopping lsbd task (pid = %d)\n", p->tsk->pid);
 	init_completion(&event);
 
+	for (i = 0; i < 1 << PART_BITS; i++)
+		fsync_dev(MKDEV(LSBD_MAJOR, (p->id << PART_BITS) + i));
+
 	p->event = &event;
 	p->stop = 1;
-	fsync_dev(dev);
 
 	send_sig(SIGKILL, p->tsk, 1);
 	wait_for_completion(&event);
 	p->tsk = NULL;
-	invalidate_bdev(bdev, 1);
-	MOD_DEC_USE_COUNT;
+
+	for (i = 0; i < 1 << PART_BITS; i++)
+		invalidate_buffers(MKDEV(LSBD_MAJOR, (p->id << PART_BITS) + i));
+}
+	
+/**
+ * lsbd_start - start LDBD device
+ * @p: LSBD device to start
+ */
+static int lsbd_start(struct lsbd *p)
+{
+	struct completion event;
+	int ret;
+
+	lsbd_info(p, "starting lsbd task\n");
+	p->stop = 0;
+	init_completion(&event);
+	p->event = &event;
+	ret = kernel_thread(lsbd_thread, p, 0);
+	if (ret < 0) {
+		lsbd_error(p, "cannot start LSBD thread: %d\n", ret);
+		return ret;
+	}
+	wait_for_completion(&event);
+	return 0;
 }
 
 /**
@@ -975,10 +1000,8 @@ static int lsbd_mount(struct lsbd *p)
 	int blksize;
 	int size;
 	int ret;
-	struct completion event;
 
 	BUG_ON(p->tsk != NULL);
-	p->stop = 0;
 	blksize = 0;
 	if (blksize_size[MAJOR(p->dev)])
 		blksize = blksize_size[MAJOR(p->dev)][MINOR(p->dev)];
@@ -1026,14 +1049,11 @@ static int lsbd_mount(struct lsbd *p)
 	lsbd_read_lcache(p);
 
 	MOD_INC_USE_COUNT;
-	init_completion(&event);
-	p->event = &event;
-	ret = kernel_thread(lsbd_thread, p, 0);
-	if (ret < 0) {
+	ret = lsbd_start(p);
+	if (ret) {
 		MOD_DEC_USE_COUNT;
 		return ret;
 	}
-	wait_for_completion(&event);
 	return 0;
 }
 
@@ -1131,19 +1151,36 @@ static int lsbd_partition(struct lsbd *p, struct lsbd_part_info *part)
 			l = vmalloc(part->size * sizeof(l[0]));
 			if (l == NULL)
 				return -ENOMEM;
+
+			/* initialize zeroed new sectors */
 			for (i = p->lsectors; i < part->size; i++)
 				l[i] = LSBD_SECT_ZERO;
+
+			/*
+			 * during lcache rebuild it's better to stop LSBD
+			 * thread for a while. Because of this we don't
+			 * need synchronization with LSBD thread. We need
+			 * only synchronization with lsbd_make_request().
+			 */
+			lsbd_stop(p);
+
+			/* copy lcache for existing sectors */
+			for (i = 0; i < p->lsectors; i++)
+				l[i] = p->lcache[i];
+
 			ol = p->lcache;
 			p->lcache = l;
 
+			lsbd_start(p);
+
 			p->lsectors = part->size;
 
 			chunk = (p->sector_size - 0x800) / sizeof(*l);
 			lsbd_write_blocks(p, p->lsectors / chunk);
 
-	/*
-	 * FIXME: implement lcache locking
-	 */
+			/*
+			 * FIXME: implement lcache locking
+			 */
 			schedule_timeout(10);
 			vfree(ol);
 		} else {
@@ -1212,8 +1249,10 @@ static int lsbd_ioctl(struct inode *inode, struct file *file,
 		unsigned int major = arg >> 20;
 		unsigned int minor = arg & 0xfffff;
 	
-		if (p->tsk != NULL)
-			lsbd_stop(p, inode->i_bdev);
+		if (p->tsk != NULL) {
+			lsbd_stop(p);
+			MOD_DEC_USE_COUNT;
+		}
 
 		err = lsbd_set_dev(p, major, minor);
 		break;
-- 
1.8.4.652.g0d6e0ce