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
  ...

1 files changed, 132 insertions, 57 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 45933c160697..704ef7fcfbf8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -353,7 +353,7 @@ static void release_inactive_stripe_list(struct r5conf *conf,
 		struct list_head *list = &temp_inactive_list[size - 1];
 
 		/*
-		 * We don't hold any lock here yet, get_active_stripe() might
+		 * We don't hold any lock here yet, raid5_get_active_stripe() might
 		 * remove stripes from the list
 		 */
 		if (!list_empty_careful(list)) {
@@ -413,7 +413,7 @@ static int release_stripe_list(struct r5conf *conf,
 	return count;
 }
 
-static void release_stripe(struct stripe_head *sh)
+void raid5_release_stripe(struct stripe_head *sh)
 {
 	struct r5conf *conf = sh->raid_conf;
 	unsigned long flags;
@@ -658,9 +658,9 @@ static int has_failed(struct r5conf *conf)
 	return 0;
 }
 
-static struct stripe_head *
-get_active_stripe(struct r5conf *conf, sector_t sector,
-		  int previous, int noblock, int noquiesce)
+struct stripe_head *
+raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
+			int previous, int noblock, int noquiesce)
 {
 	struct stripe_head *sh;
 	int hash = stripe_hash_locks_hash(sector);
@@ -755,6 +755,10 @@ static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 static bool stripe_can_batch(struct stripe_head *sh)
 {
+	struct r5conf *conf = sh->raid_conf;
+
+	if (conf->log)
+		return false;
 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 		is_full_stripe_write(sh);
@@ -858,7 +862,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
 unlock_out:
 	unlock_two_stripes(head, sh);
 out:
-	release_stripe(head);
+	raid5_release_stripe(head);
 }
 
 /* Determine if 'data_offset' or 'new_data_offset' should be used
@@ -895,6 +899,8 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 
 	might_sleep();
 
+	if (r5l_write_stripe(conf->log, sh) == 0)
+		return;
 	for (i = disks; i--; ) {
 		int rw;
 		int replace_only = 0;
@@ -1208,7 +1214,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
 	return_io(&return_bi);
 
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 }
 
 static void ops_run_biofill(struct stripe_head *sh)
@@ -1271,7 +1277,7 @@ static void ops_complete_compute(void *stripe_head_ref)
 	if (sh->check_state == check_state_compute_run)
 		sh->check_state = check_state_compute_result;
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 }
 
 /* return a pointer to the address conversion region of the scribble buffer */
@@ -1697,7 +1703,7 @@ static void ops_complete_reconstruct(void *stripe_head_ref)
 	}
 
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 }
 
 static void
@@ -1855,7 +1861,7 @@ static void ops_complete_check(void *stripe_head_ref)
 
 	sh->check_state = check_state_check_result;
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 }
 
 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
@@ -2017,7 +2023,7 @@ static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
 	/* we just created an active stripe so... */
 	atomic_inc(&conf->active_stripes);
 
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 	conf->max_nr_stripes++;
 	return 1;
 }
@@ -2236,7 +2242,7 @@ static int resize_stripes(struct r5conf *conf, int newsize)
 				if (!p)
 					err = -ENOMEM;
 			}
-		release_stripe(nsh);
+		raid5_release_stripe(nsh);
 	}
 	/* critical section pass, GFP_NOIO no longer needed */
 
@@ -2394,7 +2400,7 @@ static void raid5_end_read_request(struct bio * bi)
 	rdev_dec_pending(rdev, conf->mddev);
 	clear_bit(R5_LOCKED, &sh->dev[i].flags);
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 }
 
 static void raid5_end_write_request(struct bio *bi)
@@ -2468,14 +2474,12 @@ static void raid5_end_write_request(struct bio *bi)
 	if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
 		clear_bit(R5_LOCKED, &sh->dev[i].flags);
 	set_bit(STRIPE_HANDLE, &sh->state);
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 
 	if (sh->batch_head && sh != sh->batch_head)
-		release_stripe(sh->batch_head);
+		raid5_release_stripe(sh->batch_head);
 }
 
-static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
-
 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
 {
 	struct r5dev *dev = &sh->dev[i];
@@ -2491,7 +2495,7 @@ static void raid5_build_block(struct stripe_head *sh, int i, int previous)
 	dev->rreq.bi_private = sh;
 
 	dev->flags = 0;
-	dev->sector = compute_blocknr(sh, i, previous);
+	dev->sector = raid5_compute_blocknr(sh, i, previous);
 }
 
 static void error(struct mddev *mddev, struct md_rdev *rdev)
@@ -2524,9 +2528,9 @@ static void error(struct mddev *mddev, struct md_rdev *rdev)
  * Input: a 'big' sector number,
  * Output: index of the data and parity disk, and the sector # in them.
  */
-static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
-				     int previous, int *dd_idx,
-				     struct stripe_head *sh)
+sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
+			      int previous, int *dd_idx,
+			      struct stripe_head *sh)
 {
 	sector_t stripe, stripe2;
 	sector_t chunk_number;
@@ -2726,7 +2730,7 @@ static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
 	return new_sector;
 }
 
-static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
+sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
 {
 	struct r5conf *conf = sh->raid_conf;
 	int raid_disks = sh->disks;
@@ -3098,6 +3102,8 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
 		if (bi)
 			bitmap_end = 1;
 
+		r5l_stripe_write_finished(sh);
+
 		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 			wake_up(&conf->wait_for_overlap);
 
@@ -3141,6 +3147,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
 		 * the data has not reached the cache yet.
 		 */
 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
+		    s->failed > conf->max_degraded &&
 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
 			spin_lock_irq(&sh->stripe_lock);
@@ -3497,6 +3504,9 @@ returnbi:
 			WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
 			WARN_ON(dev->page != dev->orig_page);
 		}
+
+	r5l_stripe_write_finished(sh);
+
 	if (!discard_pending &&
 	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
 		int hash;
@@ -3939,10 +3949,10 @@ static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
 			struct stripe_head *sh2;
 			struct async_submit_ctl submit;
 
-			sector_t bn = compute_blocknr(sh, i, 1);
+			sector_t bn = raid5_compute_blocknr(sh, i, 1);
 			sector_t s = raid5_compute_sector(conf, bn, 0,
 							  &dd_idx, NULL);
-			sh2 = get_active_stripe(conf, s, 0, 1, 1);
+			sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
 			if (sh2 == NULL)
 				/* so far only the early blocks of this stripe
 				 * have been requested.  When later blocks
@@ -3952,7 +3962,7 @@ static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
 			if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
 			   test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
 				/* must have already done this block */
-				release_stripe(sh2);
+				raid5_release_stripe(sh2);
 				continue;
 			}
 
@@ -3973,7 +3983,7 @@ static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
 				set_bit(STRIPE_EXPAND_READY, &sh2->state);
 				set_bit(STRIPE_HANDLE, &sh2->state);
 			}
-			release_stripe(sh2);
+			raid5_release_stripe(sh2);
 
 		}
 	/* done submitting copies, wait for them to complete */
@@ -4008,6 +4018,7 @@ static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
 	s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
 	s->failed_num[0] = -1;
 	s->failed_num[1] = -1;
+	s->log_failed = r5l_log_disk_error(conf);
 
 	/* Now to look around and see what can be done */
 	rcu_read_lock();
@@ -4259,7 +4270,7 @@ static void break_stripe_batch_list(struct stripe_head *head_sh,
 		if (handle_flags == 0 ||
 		    sh->state & handle_flags)
 			set_bit(STRIPE_HANDLE, &sh->state);
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 	}
 	spin_lock_irq(&head_sh->stripe_lock);
 	head_sh->batch_head = NULL;
@@ -4320,6 +4331,9 @@ static void handle_stripe(struct stripe_head *sh)
 
 	analyse_stripe(sh, &s);
 
+	if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
+		goto finish;
+
 	if (s.handle_bad_blocks) {
 		set_bit(STRIPE_HANDLE, &sh->state);
 		goto finish;
@@ -4348,7 +4362,7 @@ static void handle_stripe(struct stripe_head *sh)
 	/* check if the array has lost more than max_degraded devices and,
 	 * if so, some requests might need to be failed.
 	 */
-	if (s.failed > conf->max_degraded) {
+	if (s.failed > conf->max_degraded || s.log_failed) {
 		sh->check_state = 0;
 		sh->reconstruct_state = 0;
 		break_stripe_batch_list(sh, 0);
@@ -4506,7 +4520,7 @@ static void handle_stripe(struct stripe_head *sh)
 	/* Finish reconstruct operations initiated by the expansion process */
 	if (sh->reconstruct_state == reconstruct_state_result) {
 		struct stripe_head *sh_src
-			= get_active_stripe(conf, sh->sector, 1, 1, 1);
+			= raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
 		if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
 			/* sh cannot be written until sh_src has been read.
 			 * so arrange for sh to be delayed a little
@@ -4516,11 +4530,11 @@ static void handle_stripe(struct stripe_head *sh)
 			if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
 					      &sh_src->state))
 				atomic_inc(&conf->preread_active_stripes);
-			release_stripe(sh_src);
+			raid5_release_stripe(sh_src);
 			goto finish;
 		}
 		if (sh_src)
-			release_stripe(sh_src);
+			raid5_release_stripe(sh_src);
 
 		sh->reconstruct_state = reconstruct_state_idle;
 		clear_bit(STRIPE_EXPANDING, &sh->state);
@@ -5012,7 +5026,7 @@ static void release_stripe_plug(struct mddev *mddev,
 	struct raid5_plug_cb *cb;
 
 	if (!blk_cb) {
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 		return;
 	}
 
@@ -5028,7 +5042,7 @@ static void release_stripe_plug(struct mddev *mddev,
 	if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
 		list_add_tail(&sh->lru, &cb->list);
 	else
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 }
 
 static void make_discard_request(struct mddev *mddev, struct bio *bi)
@@ -5063,12 +5077,12 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
 		DEFINE_WAIT(w);
 		int d;
 	again:
-		sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
+		sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
 		prepare_to_wait(&conf->wait_for_overlap, &w,
 				TASK_UNINTERRUPTIBLE);
 		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
 		if (test_bit(STRIPE_SYNCING, &sh->state)) {
-			release_stripe(sh);
+			raid5_release_stripe(sh);
 			schedule();
 			goto again;
 		}
@@ -5080,7 +5094,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
 			if (sh->dev[d].towrite || sh->dev[d].toread) {
 				set_bit(R5_Overlap, &sh->dev[d].flags);
 				spin_unlock_irq(&sh->stripe_lock);
-				release_stripe(sh);
+				raid5_release_stripe(sh);
 				schedule();
 				goto again;
 			}
@@ -5136,8 +5150,15 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 	bool do_prepare;
 
 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
-		md_flush_request(mddev, bi);
-		return;
+		int ret = r5l_handle_flush_request(conf->log, bi);
+
+		if (ret == 0)
+			return;
+		if (ret == -ENODEV) {
+			md_flush_request(mddev, bi);
+			return;
+		}
+		/* ret == -EAGAIN, fallback */
 	}
 
 	md_write_start(mddev, bi);
@@ -5210,7 +5231,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 			(unsigned long long)new_sector,
 			(unsigned long long)logical_sector);
 
-		sh = get_active_stripe(conf, new_sector, previous,
+		sh = raid5_get_active_stripe(conf, new_sector, previous,
 				       (bi->bi_rw&RWA_MASK), 0);
 		if (sh) {
 			if (unlikely(previous)) {
@@ -5231,7 +5252,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 					must_retry = 1;
 				spin_unlock_irq(&conf->device_lock);
 				if (must_retry) {
-					release_stripe(sh);
+					raid5_release_stripe(sh);
 					schedule();
 					do_prepare = true;
 					goto retry;
@@ -5241,14 +5262,14 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 				/* Might have got the wrong stripe_head
 				 * by accident
 				 */
-				release_stripe(sh);
+				raid5_release_stripe(sh);
 				goto retry;
 			}
 
 			if (rw == WRITE &&
 			    logical_sector >= mddev->suspend_lo &&
 			    logical_sector < mddev->suspend_hi) {
-				release_stripe(sh);
+				raid5_release_stripe(sh);
 				/* As the suspend_* range is controlled by
 				 * userspace, we want an interruptible
 				 * wait.
@@ -5271,7 +5292,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 				 * and wait a while
 				 */
 				md_wakeup_thread(mddev->thread);
-				release_stripe(sh);
+				raid5_release_stripe(sh);
 				schedule();
 				do_prepare = true;
 				goto retry;
@@ -5458,7 +5479,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 	for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
 		int j;
 		int skipped_disk = 0;
-		sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
+		sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
 		set_bit(STRIPE_EXPANDING, &sh->state);
 		atomic_inc(&conf->reshape_stripes);
 		/* If any of this stripe is beyond the end of the old
@@ -5471,7 +5492,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 			if (conf->level == 6 &&
 			    j == sh->qd_idx)
 				continue;
-			s = compute_blocknr(sh, j, 0);
+			s = raid5_compute_blocknr(sh, j, 0);
 			if (s < raid5_size(mddev, 0, 0)) {
 				skipped_disk = 1;
 				continue;
@@ -5507,10 +5528,10 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 	if (last_sector >= mddev->dev_sectors)
 		last_sector = mddev->dev_sectors - 1;
 	while (first_sector <= last_sector) {
-		sh = get_active_stripe(conf, first_sector, 1, 0, 1);
+		sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
 		set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
 		set_bit(STRIPE_HANDLE, &sh->state);
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 		first_sector += STRIPE_SECTORS;
 	}
 	/* Now that the sources are clearly marked, we can release
@@ -5519,7 +5540,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 	while (!list_empty(&stripes)) {
 		sh = list_entry(stripes.next, struct stripe_head, lru);
 		list_del_init(&sh->lru);
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 	}
 	/* If this takes us to the resync_max point where we have to pause,
 	 * then we need to write out the superblock.
@@ -5615,11 +5636,11 @@ static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int
 		return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
 	}
 
-	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
+	bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
 
-	sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
+	sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
 	if (sh == NULL) {
-		sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
+		sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
 		/* make sure we don't swamp the stripe cache if someone else
 		 * is trying to get access
 		 */
@@ -5643,7 +5664,7 @@ static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int
 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
 	set_bit(STRIPE_HANDLE, &sh->state);
 
-	release_stripe(sh);
+	raid5_release_stripe(sh);
 
 	return STRIPE_SECTORS;
 }
@@ -5682,7 +5703,7 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
 			/* already done this stripe */
 			continue;
 
-		sh = get_active_stripe(conf, sector, 0, 1, 1);
+		sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
 
 		if (!sh) {
 			/* failed to get a stripe - must wait */
@@ -5692,7 +5713,7 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
 		}
 
 		if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
-			release_stripe(sh);
+			raid5_release_stripe(sh);
 			raid5_set_bi_processed_stripes(raid_bio, scnt);
 			conf->retry_read_aligned = raid_bio;
 			return handled;
@@ -5700,7 +5721,7 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
 
 		set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
 		handle_stripe(sh);
-		release_stripe(sh);
+		raid5_release_stripe(sh);
 		handled++;
 	}
 	remaining = raid5_dec_bi_active_stripes(raid_bio);
@@ -5730,8 +5751,12 @@ static int handle_active_stripes(struct r5conf *conf, int group,
 		for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
 			if (!list_empty(temp_inactive_list + i))
 				break;
-		if (i == NR_STRIPE_HASH_LOCKS)
+		if (i == NR_STRIPE_HASH_LOCKS) {
+			spin_unlock_irq(&conf->device_lock);
+			r5l_flush_stripe_to_raid(conf->log);
+			spin_lock_irq(&conf->device_lock);
 			return batch_size;
+		}
 		release_inactive = true;
 	}
 	spin_unlock_irq(&conf->device_lock);
@@ -5739,6 +5764,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
 	release_inactive_stripe_list(conf, temp_inactive_list,
 				     NR_STRIPE_HASH_LOCKS);
 
+	r5l_flush_stripe_to_raid(conf->log);
 	if (release_inactive) {
 		spin_lock_irq(&conf->device_lock);
 		return 0;
@@ -5746,6 +5772,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
 
 	for (i = 0; i < batch_size; i++)
 		handle_stripe(batch[i]);
+	r5l_write_stripe_run(conf->log);
 
 	cond_resched();
 
@@ -5879,6 +5906,8 @@ static void raid5d(struct md_thread *thread)
 		mutex_unlock(&conf->cache_size_mutex);
 	}
 
+	r5l_flush_stripe_to_raid(conf->log);
+
 	async_tx_issue_pending_all();
 	blk_finish_plug(&plug);
 
@@ -6316,8 +6345,11 @@ static void raid5_free_percpu(struct r5conf *conf)
 
 static void free_conf(struct r5conf *conf)
 {
+	if (conf->log)
+		r5l_exit_log(conf->log);
 	if (conf->shrinker.seeks)
 		unregister_shrinker(&conf->shrinker);
+
 	free_thread_groups(conf);
 	shrink_stripes(conf);
 	raid5_free_percpu(conf);
@@ -6530,7 +6562,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	rdev_for_each(rdev, mddev) {
 		raid_disk = rdev->raid_disk;
 		if (raid_disk >= max_disks
-		    || raid_disk < 0)
+		    || raid_disk < 0 || test_bit(Journal, &rdev->flags))
 			continue;
 		disk = conf->disks + raid_disk;
 
@@ -6650,6 +6682,7 @@ static int run(struct mddev *mddev)
 	int working_disks = 0;
 	int dirty_parity_disks = 0;
 	struct md_rdev *rdev;
+	struct md_rdev *journal_dev = NULL;
 	sector_t reshape_offset = 0;
 	int i;
 	long long min_offset_diff = 0;
@@ -6662,6 +6695,11 @@ static int run(struct mddev *mddev)
 
 	rdev_for_each(rdev, mddev) {
 		long long diff;
+
+		if (test_bit(Journal, &rdev->flags)) {
+			journal_dev = rdev;
+			continue;
+		}
 		if (rdev->raid_disk < 0)
 			continue;
 		diff = (rdev->new_data_offset - rdev->data_offset);
@@ -6695,6 +6733,12 @@ static int run(struct mddev *mddev)
 		int chunk_sectors;
 		int new_data_disks;
 
+		if (journal_dev) {
+			printk(KERN_ERR "md/raid:%s: don't support reshape with journal - aborting.\n",
+			       mdname(mddev));
+			return -EINVAL;
+		}
+
 		if (mddev->new_level != mddev->level) {
 			printk(KERN_ERR "md/raid:%s: unsupported reshape "
 			       "required - aborting.\n",
@@ -6770,6 +6814,13 @@ static int run(struct mddev *mddev)
 	if (IS_ERR(conf))
 		return PTR_ERR(conf);
 
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags) && !journal_dev) {
+		printk(KERN_ERR "md/raid:%s: journal disk is missing, force array readonly\n",
+		       mdname(mddev));
+		mddev->ro = 1;
+		set_disk_ro(mddev->gendisk, 1);
+	}
+
 	conf->min_offset_diff = min_offset_diff;
 	mddev->thread = conf->thread;
 	conf->thread = NULL;
@@ -6973,6 +7024,14 @@ static int run(struct mddev *mddev)
 						mddev->queue);
 	}
 
+	if (journal_dev) {
+		char b[BDEVNAME_SIZE];
+
+		printk(KERN_INFO"md/raid:%s: using device %s as journal\n",
+		       mdname(mddev), bdevname(journal_dev->bdev, b));
+		r5l_init_log(conf, journal_dev);
+	}
+
 	return 0;
 abort:
 	md_unregister_thread(&mddev->thread);
@@ -7082,6 +7141,15 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 	struct disk_info *p = conf->disks + number;
 
 	print_raid5_conf(conf);
+	if (test_bit(Journal, &rdev->flags)) {
+		/*
+		 * journal disk is not removable, but we need give a chance to
+		 * update superblock of other disks. Otherwise journal disk
+		 * will be considered as 'fresh'
+		 */
+		set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		return -EINVAL;
+	}
 	if (rdev == p->rdev)
 		rdevp = &p->rdev;
 	else if (rdev == p->replacement)
@@ -7144,6 +7212,8 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	int first = 0;
 	int last = conf->raid_disks - 1;
 
+	if (test_bit(Journal, &rdev->flags))
+		return -EINVAL;
 	if (mddev->recovery_disabled == conf->recovery_disabled)
 		return -EBUSY;
 
@@ -7205,6 +7275,8 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
 	sector_t newsize;
 	struct r5conf *conf = mddev->private;
 
+	if (conf->log)
+		return -EINVAL;
 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
 	if (mddev->external_size &&
@@ -7256,6 +7328,8 @@ static int check_reshape(struct mddev *mddev)
 {
 	struct r5conf *conf = mddev->private;
 
+	if (conf->log)
+		return -EINVAL;
 	if (mddev->delta_disks == 0 &&
 	    mddev->new_layout == mddev->layout &&
 	    mddev->new_chunk_sectors == mddev->chunk_sectors)
@@ -7532,6 +7606,7 @@ static void raid5_quiesce(struct mddev *mddev, int state)
 		unlock_all_device_hash_locks_irq(conf);
 		break;
 	}
+	r5l_quiesce(conf->log, state);
 }
 
 static void *raid45_takeover_raid0(struct mddev *mddev, int level)