Merge tag 'md/4.4' of git://neil.brown.name/md

Pull md updates from Neil Brown:
 "Two major components to this update.

   1) The clustered-raid1 support from SUSE is nearly complete.  There
      are a few outstanding issues being worked on.  Maybe half a dozen
      patches will bring this to a usable state.

   2) The first stage of journalled-raid5 support from Facebook makes an
      appearance.  With a journal device configured (typically NVRAM or
      SSD), the "RAID5 write hole" should be closed - a crash during
      degraded operations cannot result in data corruption.

      The next stage will be to use the journal as a write-behind cache
      so that latency can be reduced and in some cases throughput
      increased by performing more full-stripe writes.

* tag 'md/4.4' of git://neil.brown.name/md: (66 commits)
  MD: when RAID journal is missing/faulty, block RESTART_ARRAY_RW
  MD: set journal disk ->raid_disk
  MD: kick out journal disk if it's not fresh
  raid5-cache: start raid5 readonly if journal is missing
  MD: add new bit to indicate raid array with journal
  raid5-cache: IO error handling
  raid5: journal disk can't be removed
  raid5-cache: add trim support for log
  MD: fix info output for journal disk
  raid5-cache: use bio chaining
  raid5-cache: small log->seq cleanup
  raid5-cache: new helper: r5_reserve_log_entry
  raid5-cache: inline r5l_alloc_io_unit into r5l_new_meta
  raid5-cache: take rdev->data_offset into account early on
  raid5-cache: refactor bio allocation
  raid5-cache: clean up r5l_get_meta
  raid5-cache: simplify state machine when caches flushes are not needed
  raid5-cache: factor out a helper to run all stripes for an I/O unit
  raid5-cache: rename flushed_ios to finished_ios
  raid5-cache: free I/O units earlier
  ...

drivers/md/Makefile

@@ -17,7 +17,7 @@ dm-cache-smq-y   += dm-cache-policy-smq.o
 dm-cache-cleaner-y += dm-cache-policy-cleaner.o
 dm-era-y	+= dm-era-target.o
 md-mod-y	+= md.o bitmap.o
-raid456-y	+= raid5.o
+raid456-y	+= raid5.o raid5-cache.o
 
 # Note: link order is important.  All raid personalities
 # and must come before md.o, as they each initialise 

drivers/md/bitmap.c

@@ -613,12 +613,10 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
 	write_behind = le32_to_cpu(sb->write_behind);
 	sectors_reserved = le32_to_cpu(sb->sectors_reserved);
-	/* XXX: This is a hack to ensure that we don't use clustering
-	 *  in case:
-	 *	- dm-raid is in use and
-	 *	- the nodes written in bitmap_sb is erroneous.
+	/* Setup nodes/clustername only if bitmap version is
+	 * cluster-compatible
 	 */
-	if (!bitmap->mddev->sync_super) {
+	if (sb->version == cpu_to_le32(BITMAP_MAJOR_CLUSTERED)) {
 		nodes = le32_to_cpu(sb->nodes);
 		strlcpy(bitmap->mddev->bitmap_info.cluster_name,
 				sb->cluster_name, 64);
@@ -628,7 +626,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
 		reason = "bad magic";
 	else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
-		 le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
+		 le32_to_cpu(sb->version) > BITMAP_MAJOR_CLUSTERED)
 		reason = "unrecognized superblock version";
 	else if (chunksize < 512)
 		reason = "bitmap chunksize too small";
@@ -1572,7 +1570,7 @@ void bitmap_close_sync(struct bitmap *bitmap)
 }
 EXPORT_SYMBOL(bitmap_close_sync);
 
-void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
+void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force)
 {
 	sector_t s = 0;
 	sector_t blocks;
@@ -1583,7 +1581,7 @@ void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector)
 		bitmap->last_end_sync = jiffies;
 		return;
 	}
-	if (time_before(jiffies, (bitmap->last_end_sync
+	if (!force && time_before(jiffies, (bitmap->last_end_sync
 				  + bitmap->mddev->bitmap_info.daemon_sleep)))
 		return;
 	wait_event(bitmap->mddev->recovery_wait,

drivers/md/bitmap.h

@@ -9,8 +9,10 @@
 #define BITMAP_MAJOR_LO 3
 /* version 4 insists the bitmap is in little-endian order
  * with version 3, it is host-endian which is non-portable
+ * Version 5 is currently set only for clustered devices
  */
 #define BITMAP_MAJOR_HI 4
+#define BITMAP_MAJOR_CLUSTERED 5
 #define	BITMAP_MAJOR_HOSTENDIAN 3
 
 /*
@@ -255,7 +257,7 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
 void bitmap_close_sync(struct bitmap *bitmap);
-void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector);
+void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force);
 
 void bitmap_unplug(struct bitmap *bitmap);
 void bitmap_daemon_work(struct mddev *mddev);