Fix problems with raid1 resync code

Fix bugs discovered by Paul.Clements@steeleye.com.

Routines were called while spinlocks were held which shouldn't
have been called in that situation (raid1_grow_buffers, close_sync).

At end of resync, start_future (sectors) was set to
sb->size+1 (K) in instead of (sb->size<<1)+1.


 ----------- Diffstat output ------------
 ./drivers/md/raid1.c |   54 +++++++++++++++++++++++++++++++++++++--------------
 1 files changed, 40 insertions(+), 14 deletions(-)

--- ./drivers/md/raid1.c	2002/03/25 21:53:59	1.1
+++ ./drivers/md/raid1.c	2002/03/26 01:47:56	1.2
@@ -269,8 +269,9 @@
 static int raid1_grow_buffers (raid1_conf_t *conf, int cnt)
 {
 	int i = 0;
+	struct raid1_bh *head = NULL, **tail;
+	tail = &head;
 
-	md_spin_lock_irq(&conf->device_lock);
 	while (i < cnt) {
 		struct raid1_bh *r1_bh;
 		struct page *page;
@@ -287,10 +288,18 @@
 		memset(r1_bh, 0, sizeof(*r1_bh));
 		r1_bh->bh_req.b_page = page;
 		r1_bh->bh_req.b_data = page_address(page);
-		r1_bh->next_r1 = conf->freebuf;
-		conf->freebuf = r1_bh;
+		*tail = r1_bh;
+		r1_bh->next_r1 = NULL;
+		tail = & r1_bh->next_r1;
 		i++;
 	}
+	/* this lock probably isn't needed, as at the time when
+	 * we are allocating buffers, nobody else will be touching the
+	 * freebuf list.  But it doesn't hurt....
+	 */
+	md_spin_lock_irq(&conf->device_lock);
+	*tail = conf->freebuf;
+	conf->freebuf = head;
 	md_spin_unlock_irq(&conf->device_lock);
 	return i;
 }
@@ -825,7 +834,7 @@
 	conf->start_ready = conf->start_pending;
 	wait_event_lock_irq(conf->wait_ready, !conf->cnt_pending, conf->segment_lock);
 	conf->start_active =conf->start_ready = conf->start_pending = conf->start_future;
-	conf->start_future = mddev->sb->size+1;
+	conf->start_future = (mddev->sb->size<<1)+1;
 	conf->cnt_pending = conf->cnt_future;
 	conf->cnt_future = 0;
 	conf->phase = conf->phase ^1;
@@ -849,6 +858,14 @@
 	mdk_rdev_t *spare_rdev, *failed_rdev;
 
 	print_raid1_conf(conf);
+
+	switch (state) {
+	case DISKOP_SPARE_ACTIVE:
+	case DISKOP_SPARE_INACTIVE:
+		/* need to wait for pending sync io before locking device */
+		close_sync(conf);
+	}
+
 	md_spin_lock_irq(&conf->device_lock);
 	/*
 	 * find the disk ...
@@ -951,7 +968,11 @@
 	 * Deactivate a spare disk:
 	 */
 	case DISKOP_SPARE_INACTIVE:
-		close_sync(conf);
+		if (conf->start_future > 0) {
+			MD_BUG();
+			err = -EBUSY;
+			break;
+		}
 		sdisk = conf->mirrors + spare_disk;
 		sdisk->operational = 0;
 		sdisk->write_only = 0;
@@ -964,7 +985,11 @@
 	 * property)
 	 */
 	case DISKOP_SPARE_ACTIVE:
-		close_sync(conf);
+		if (conf->start_future > 0) {
+			MD_BUG();
+			err = -EBUSY;
+			break;
+		}
 		sdisk = conf->mirrors + spare_disk;
 		fdisk = conf->mirrors + failed_disk;
 
@@ -1328,23 +1353,25 @@
 	int bsize;
 	int disk;
 	int block_nr;
+	int buffs;
 
+	if (!sector_nr) {
+		/* we want enough buffers to hold twice the window of 128*/
+		buffs = 128 *2 / (PAGE_SIZE>>9);
+		buffs = raid1_grow_buffers(conf, buffs);
+		if (buffs < 2)
+			goto nomem;
+		conf->window = buffs*(PAGE_SIZE>>9)/2;
+	}
 	spin_lock_irq(&conf->segment_lock);
 	if (!sector_nr) {
 		/* initialize ...*/
-		int buffs;
 		conf->start_active = 0;
 		conf->start_ready = 0;
 		conf->start_pending = 0;
 		conf->start_future = 0;
 		conf->phase = 0;
-		/* we want enough buffers to hold twice the window of 128*/
-		buffs = 128 *2 / (PAGE_SIZE>>9);
-		buffs = raid1_grow_buffers(conf, buffs);
-		if (buffs < 2)
-			goto nomem;
 		
-		conf->window = buffs*(PAGE_SIZE>>9)/2;
 		conf->cnt_future += conf->cnt_done+conf->cnt_pending;
 		conf->cnt_done = conf->cnt_pending = 0;
 		if (conf->cnt_ready || conf->cnt_active)
@@ -1429,7 +1456,6 @@
 
 nomem:
 	raid1_shrink_buffers(conf);
-	spin_unlock_irq(&conf->segment_lock);
 	return -ENOMEM;
 }