Merge tag 'md-3.8' of git://neil.brown.name/md

Pull md update from Neil Brown:
 "Mostly just little fixes.  Probably biggest part is AVX accelerated
  RAID6 calculations."

* tag 'md-3.8' of git://neil.brown.name/md:
  md/raid5: add blktrace calls
  md/raid5: use async_tx_quiesce() instead of open-coding it.
  md: Use ->curr_resync as last completed request when cleanly aborting resync.
  lib/raid6: build proper files on corresponding arch
  lib/raid6: Add AVX2 optimized gen_syndrome functions
  lib/raid6: Add AVX2 optimized recovery functions
  md: Update checkpoint of resync/recovery based on time.
  md:Add place to update ->recovery_cp.
  md.c: re-indent various 'switch' statements.
  md: close race between removing and adding a device.
  md: removed unused variable in calc_sb_1_csm.

drivers/md/md.h

@@ -307,6 +307,7 @@ struct mddev {
 	 * REQUEST:  user-space has requested a sync (used with SYNC)
 	 * CHECK:    user-space request for check-only, no repair
 	 * RESHAPE:  A reshape is happening
+	 * ERROR:    sync-action interrupted because io-error
 	 *
 	 * If neither SYNC or RESHAPE are set, then it is a recovery.
 	 */
@@ -320,6 +321,7 @@ struct mddev {
 #define	MD_RECOVERY_CHECK	7
 #define MD_RECOVERY_RESHAPE	8
 #define	MD_RECOVERY_FROZEN	9
+#define	MD_RECOVERY_ERROR	10
 
 	unsigned long			recovery;
 	/* If a RAID personality determines that recovery (of a particular