3 bug md fixes for 3.20

yet-another-livelock in raid5, and a problem with write errors
 to 4K-block devices.
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Merge tag 'md/3.20-fixes' of git://neil.brown.name/md

Pull md bugfixes from Neil Brown:
 "Three bug md fixes for 3.20

  yet-another-livelock in raid5, and a problem with write errors to
  4K-block devices"

* tag 'md/3.20-fixes' of git://neil.brown.name/md:
  md/raid5: Fix livelock when array is both resyncing and degraded.
  md/raid10: round up to bdev_logical_block_size in narrow_write_error.
  md/raid1: round up to bdev_logical_block_size in narrow_write_error

drivers/md/raid1.c

@@ -2196,7 +2196,8 @@ static int narrow_write_error(struct r1bio *r1_bio, int i)
 	if (rdev->badblocks.shift < 0)
 		return 0;
 
-	block_sectors = 1 << rdev->badblocks.shift;
+	block_sectors = roundup(1 << rdev->badblocks.shift,
+				bdev_logical_block_size(rdev->bdev) >> 9);
 	sector = r1_bio->sector;
 	sectors = ((sector + block_sectors)
 		   & ~(sector_t)(block_sectors - 1))

drivers/md/raid10.c

@@ -2572,7 +2572,8 @@ static int narrow_write_error(struct r10bio *r10_bio, int i)
 	if (rdev->badblocks.shift < 0)
 		return 0;
 
-	block_sectors = 1 << rdev->badblocks.shift;
+	block_sectors = roundup(1 << rdev->badblocks.shift,
+				bdev_logical_block_size(rdev->bdev) >> 9);
 	sector = r10_bio->sector;
 	sectors = ((r10_bio->sector + block_sectors)
 		   & ~(sector_t)(block_sectors - 1))

drivers/md/raid5.c

@@ -3170,7 +3170,8 @@ static void handle_stripe_dirtying(struct r5conf *conf,
 	 * generate correct data from the parity.
 	 */
 	if (conf->max_degraded == 2 ||
-	    (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
+	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
+	     s->failed == 0)) {
 		/* Calculate the real rcw later - for now make it
 		 * look like rcw is cheaper
 		 */