Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md

Pull MD updates from Shaohua Li:

 - a raid5 writeback cache feature.

   The goal is to aggregate writes to make full stripe write and reduce
   read-modify-write. It's helpful for workload which does sequential
   write and follows fsync for example. This feature is experimental and
   off by default right now.

 - FAILFAST support.

   This fails IOs to broken raid disks quickly, so can improve latency.
   It's mainly for DASD storage, but some patches help normal raid array
   too.

 - support bad block for raid array with external metadata

 - AVX2 instruction support for raid6 parity calculation

 - normalize MD info output

 - add missing blktrace

 - other bug fixes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: (66 commits)
  md: separate flags for superblock changes
  md: MD_RECOVERY_NEEDED is set for mddev->recovery
  md: takeover should clear unrelated bits
  md/r5cache: after recovery, increase journal seq by 10000
  md/raid5-cache: fix crc in rewrite_data_only_stripes()
  md/raid5-cache: no recovery is required when create super-block
  md: fix refcount problem on mddev when stopping array.
  md/r5cache: do r5c_update_log_state after log recovery
  md/raid5-cache: adjust the write position of the empty block if no data blocks
  md/r5cache: run_no_space_stripes() when R5C_LOG_CRITICAL == 0
  md/raid5: limit request size according to implementation limits
  md/raid5-cache: do not need to set STRIPE_PREREAD_ACTIVE repeatedly
  md/raid5-cache: remove the unnecessary next_cp_seq field from the r5l_log
  md/raid5-cache: release the stripe_head at the appropriate location
  md/raid5-cache: use ring add to prevent overflow
  md/raid5-cache: remove unnecessary function parameters
  raid5-cache: don't set STRIPE_R5C_PARTIAL_STRIPE flag while load stripe into cache
  raid5-cache: add another check conditon before replaying one stripe
  md/r5cache: enable IRQs on error path
  md/r5cache: handle alloc_page failure
  ...

include/uapi/linux/raid/md_p.h

@@ -84,6 +84,10 @@
 #define MD_DISK_CANDIDATE	5 /* disk is added as spare (local) until confirmed
 				   * For clustered enviroments only.
 				   */
+#define MD_DISK_FAILFAST	10 /* Send REQ_FAILFAST if there are multiple
+				    * devices available - and don't try to
+				    * correct read errors.
+				    */
 
 #define	MD_DISK_WRITEMOSTLY	9 /* disk is "write-mostly" is RAID1 config.
 				   * read requests will only be sent here in
@@ -265,8 +269,9 @@ struct mdp_superblock_1 {
 	__le32	dev_number;	/* permanent identifier of this  device - not role in raid */
 	__le32	cnt_corrected_read; /* number of read errors that were corrected by re-writing */
 	__u8	device_uuid[16]; /* user-space setable, ignored by kernel */
-	__u8	devflags;	/* per-device flags.  Only one defined...*/
+	__u8	devflags;	/* per-device flags.  Only two defined...*/
 #define	WriteMostly1	1	/* mask for writemostly flag in above */
+#define	FailFast1	2	/* Should avoid retries and fixups and just fail */
 	/* Bad block log.  If there are any bad blocks the feature flag is set.
 	 * If offset and size are non-zero, that space is reserved and available
 	 */