1 files changed, 602 insertions, 0 deletions

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 390be840c764..3aa7eccde620 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2015 Shaohua Li <shli@fb.com>
+ * Copyright (C) 2016 Song Liu <songliubraving@fb.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -1354,6 +1355,9 @@ struct r5l_recovery_ctx {
 	sector_t meta_total_blocks;	/* total size of current meta and data */
 	sector_t pos;			/* recovery position */
 	u64 seq;			/* recovery position seq */
+	int data_parity_stripes;	/* number of data_parity stripes */
+	int data_only_stripes;		/* number of data_only stripes */
+	struct list_head cached_list;
 };
 
 static int r5l_recovery_read_meta_block(struct r5l_log *log,
@@ -1576,6 +1580,590 @@ static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
 	return 0;
 }
 
+/*
+ * r5l_recovery_load_data and r5l_recovery_load_parity uses flag R5_Wantwrite
+ * to mark valid (potentially not flushed) data in the journal.
+ *
+ * We already verified checksum in r5l_recovery_verify_data_checksum_for_mb,
+ * so there should not be any mismatch here.
+ */
+static void r5l_recovery_load_data(struct r5l_log *log,
+				   struct stripe_head *sh,
+				   struct r5l_recovery_ctx *ctx,
+				   struct r5l_payload_data_parity *payload,
+				   sector_t log_offset)
+{
+	struct mddev *mddev = log->rdev->mddev;
+	struct r5conf *conf = mddev->private;
+	int dd_idx;
+
+	raid5_compute_sector(conf,
+			     le64_to_cpu(payload->location), 0,
+			     &dd_idx, sh);
+	sync_page_io(log->rdev, log_offset, PAGE_SIZE,
+		     sh->dev[dd_idx].page, REQ_OP_READ, 0, false);
+	sh->dev[dd_idx].log_checksum =
+		le32_to_cpu(payload->checksum[0]);
+	ctx->meta_total_blocks += BLOCK_SECTORS;
+
+	set_bit(R5_Wantwrite, &sh->dev[dd_idx].flags);
+	set_bit(STRIPE_R5C_CACHING, &sh->state);
+}
+
+static void r5l_recovery_load_parity(struct r5l_log *log,
+				     struct stripe_head *sh,
+				     struct r5l_recovery_ctx *ctx,
+				     struct r5l_payload_data_parity *payload,
+				     sector_t log_offset)
+{
+	struct mddev *mddev = log->rdev->mddev;
+	struct r5conf *conf = mddev->private;
+
+	ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
+	sync_page_io(log->rdev, log_offset, PAGE_SIZE,
+		     sh->dev[sh->pd_idx].page, REQ_OP_READ, 0, false);
+	sh->dev[sh->pd_idx].log_checksum =
+		le32_to_cpu(payload->checksum[0]);
+	set_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags);
+
+	if (sh->qd_idx >= 0) {
+		sync_page_io(log->rdev,
+			     r5l_ring_add(log, log_offset, BLOCK_SECTORS),
+			     PAGE_SIZE, sh->dev[sh->qd_idx].page,
+			     REQ_OP_READ, 0, false);
+		sh->dev[sh->qd_idx].log_checksum =
+			le32_to_cpu(payload->checksum[1]);
+		set_bit(R5_Wantwrite, &sh->dev[sh->qd_idx].flags);
+	}
+	clear_bit(STRIPE_R5C_CACHING, &sh->state);
+}
+
+static void r5l_recovery_reset_stripe(struct stripe_head *sh)
+{
+	int i;
+
+	sh->state = 0;
+	sh->log_start = MaxSector;
+	for (i = sh->disks; i--; )
+		sh->dev[i].flags = 0;
+}
+
+static void
+r5l_recovery_replay_one_stripe(struct r5conf *conf,
+			       struct stripe_head *sh,
+			       struct r5l_recovery_ctx *ctx)
+{
+	struct md_rdev *rdev, *rrdev;
+	int disk_index;
+	int data_count = 0;
+
+	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
+		if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
+			continue;
+		if (disk_index == sh->qd_idx || disk_index == sh->pd_idx)
+			continue;
+		data_count++;
+	}
+
+	/*
+	 * stripes that only have parity must have been flushed
+	 * before the crash that we are now recovering from, so
+	 * there is nothing more to recovery.
+	 */
+	if (data_count == 0)
+		goto out;
+
+	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
+		if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
+			continue;
+
+		/* in case device is broken */
+		rcu_read_lock();
+		rdev = rcu_dereference(conf->disks[disk_index].rdev);
+		if (rdev) {
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			sync_page_io(rdev, sh->sector, PAGE_SIZE,
+				     sh->dev[disk_index].page, REQ_OP_WRITE, 0,
+				     false);
+			rdev_dec_pending(rdev, rdev->mddev);
+			rcu_read_lock();
+		}
+		rrdev = rcu_dereference(conf->disks[disk_index].replacement);
+		if (rrdev) {
+			atomic_inc(&rrdev->nr_pending);
+			rcu_read_unlock();
+			sync_page_io(rrdev, sh->sector, PAGE_SIZE,
+				     sh->dev[disk_index].page, REQ_OP_WRITE, 0,
+				     false);
+			rdev_dec_pending(rrdev, rrdev->mddev);
+			rcu_read_lock();
+		}
+		rcu_read_unlock();
+	}
+	ctx->data_parity_stripes++;
+out:
+	r5l_recovery_reset_stripe(sh);
+}
+
+static struct stripe_head *
+r5c_recovery_alloc_stripe(struct r5conf *conf,
+			  struct list_head *recovery_list,
+			  sector_t stripe_sect,
+			  sector_t log_start)
+{
+	struct stripe_head *sh;
+
+	sh = raid5_get_active_stripe(conf, stripe_sect, 0, 1, 0);
+	if (!sh)
+		return NULL;  /* no more stripe available */
+
+	r5l_recovery_reset_stripe(sh);
+	sh->log_start = log_start;
+
+	return sh;
+}
+
+static struct stripe_head *
+r5c_recovery_lookup_stripe(struct list_head *list, sector_t sect)
+{
+	struct stripe_head *sh;
+
+	list_for_each_entry(sh, list, lru)
+		if (sh->sector == sect)
+			return sh;
+	return NULL;
+}
+
+static void
+r5c_recovery_drop_stripes(struct list_head *cached_stripe_list,
+			  struct r5l_recovery_ctx *ctx)
+{
+	struct stripe_head *sh, *next;
+
+	list_for_each_entry_safe(sh, next, cached_stripe_list, lru) {
+		r5l_recovery_reset_stripe(sh);
+		list_del_init(&sh->lru);
+		raid5_release_stripe(sh);
+	}
+}
+
+static void
+r5c_recovery_replay_stripes(struct list_head *cached_stripe_list,
+			    struct r5l_recovery_ctx *ctx)
+{
+	struct stripe_head *sh, *next;
+
+	list_for_each_entry_safe(sh, next, cached_stripe_list, lru)
+		if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
+			r5l_recovery_replay_one_stripe(sh->raid_conf, sh, ctx);
+			list_del_init(&sh->lru);
+			raid5_release_stripe(sh);
+		}
+}
+
+/* if matches return 0; otherwise return -EINVAL */
+static int
+r5l_recovery_verify_data_checksum(struct r5l_log *log, struct page *page,
+				  sector_t log_offset, __le32 log_checksum)
+{
+	void *addr;
+	u32 checksum;
+
+	sync_page_io(log->rdev, log_offset, PAGE_SIZE,
+		     page, REQ_OP_READ, 0, false);
+	addr = kmap_atomic(page);
+	checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
+	kunmap_atomic(addr);
+	return (le32_to_cpu(log_checksum) == checksum) ? 0 : -EINVAL;
+}
+
+/*
+ * before loading data to stripe cache, we need verify checksum for all data,
+ * if there is mismatch for any data page, we drop all data in the mata block
+ */
+static int
+r5l_recovery_verify_data_checksum_for_mb(struct r5l_log *log,
+					 struct r5l_recovery_ctx *ctx)
+{
+	struct mddev *mddev = log->rdev->mddev;
+	struct r5conf *conf = mddev->private;
+	struct r5l_meta_block *mb = page_address(ctx->meta_page);
+	sector_t mb_offset = sizeof(struct r5l_meta_block);
+	sector_t log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
+	struct page *page;
+	struct r5l_payload_data_parity *payload;
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	while (mb_offset < le32_to_cpu(mb->meta_size)) {
+		payload = (void *)mb + mb_offset;
+
+		if (payload->header.type == R5LOG_PAYLOAD_DATA) {
+			if (r5l_recovery_verify_data_checksum(
+				    log, page, log_offset,
+				    payload->checksum[0]) < 0)
+				goto mismatch;
+		} else if (payload->header.type == R5LOG_PAYLOAD_PARITY) {
+			if (r5l_recovery_verify_data_checksum(
+				    log, page, log_offset,
+				    payload->checksum[0]) < 0)
+				goto mismatch;
+			if (conf->max_degraded == 2 && /* q for RAID 6 */
+			    r5l_recovery_verify_data_checksum(
+				    log, page,
+				    r5l_ring_add(log, log_offset,
+						 BLOCK_SECTORS),
+				    payload->checksum[1]) < 0)
+				goto mismatch;
+		} else /* not R5LOG_PAYLOAD_DATA or R5LOG_PAYLOAD_PARITY */
+			goto mismatch;
+
+		log_offset = r5l_ring_add(log, log_offset,
+					  le32_to_cpu(payload->size));
+
+		mb_offset += sizeof(struct r5l_payload_data_parity) +
+			sizeof(__le32) *
+			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+	}
+
+	put_page(page);
+	return 0;
+
+mismatch:
+	put_page(page);
+	return -EINVAL;
+}
+
+/*
+ * Analyze all data/parity pages in one meta block
+ * Returns:
+ * 0 for success
+ * -EINVAL for unknown playload type
+ * -EAGAIN for checksum mismatch of data page
+ * -ENOMEM for run out of memory (alloc_page failed or run out of stripes)
+ */
+static int
+r5c_recovery_analyze_meta_block(struct r5l_log *log,
+				struct r5l_recovery_ctx *ctx,
+				struct list_head *cached_stripe_list)
+{
+	struct mddev *mddev = log->rdev->mddev;
+	struct r5conf *conf = mddev->private;
+	struct r5l_meta_block *mb;
+	struct r5l_payload_data_parity *payload;
+	int mb_offset;
+	sector_t log_offset;
+	sector_t stripe_sect;
+	struct stripe_head *sh;
+	int ret;
+
+	/*
+	 * for mismatch in data blocks, we will drop all data in this mb, but
+	 * we will still read next mb for other data with FLUSH flag, as
+	 * io_unit could finish out of order.
+	 */
+	ret = r5l_recovery_verify_data_checksum_for_mb(log, ctx);
+	if (ret == -EINVAL)
+		return -EAGAIN;
+	else if (ret)
+		return ret;   /* -ENOMEM duo to alloc_page() failed */
+
+	mb = page_address(ctx->meta_page);
+	mb_offset = sizeof(struct r5l_meta_block);
+	log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
+
+	while (mb_offset < le32_to_cpu(mb->meta_size)) {
+		int dd;
+
+		payload = (void *)mb + mb_offset;
+		stripe_sect = (payload->header.type == R5LOG_PAYLOAD_DATA) ?
+			raid5_compute_sector(
+				conf, le64_to_cpu(payload->location), 0, &dd,
+				NULL)
+			: le64_to_cpu(payload->location);
+
+		sh = r5c_recovery_lookup_stripe(cached_stripe_list,
+						stripe_sect);
+
+		if (!sh) {
+			sh = r5c_recovery_alloc_stripe(conf, cached_stripe_list,
+						       stripe_sect, ctx->pos);
+			/*
+			 * cannot get stripe from raid5_get_active_stripe
+			 * try replay some stripes
+			 */
+			if (!sh) {
+				r5c_recovery_replay_stripes(
+					cached_stripe_list, ctx);
+				sh = r5c_recovery_alloc_stripe(
+					conf, cached_stripe_list,
+					stripe_sect, ctx->pos);
+			}
+			if (!sh) {
+				pr_debug("md/raid:%s: Increasing stripe cache size to %d to recovery data on journal.\n",
+					mdname(mddev),
+					conf->min_nr_stripes * 2);
+				raid5_set_cache_size(mddev,
+						     conf->min_nr_stripes * 2);
+				sh = r5c_recovery_alloc_stripe(
+					conf, cached_stripe_list, stripe_sect,
+					ctx->pos);
+			}
+			if (!sh) {
+				pr_err("md/raid:%s: Cannot get enough stripes due to memory pressure. Recovery failed.\n",
+				       mdname(mddev));
+				return -ENOMEM;
+			}
+			list_add_tail(&sh->lru, cached_stripe_list);
+		}
+
+		if (payload->header.type == R5LOG_PAYLOAD_DATA) {
+			if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
+				r5l_recovery_replay_one_stripe(conf, sh, ctx);
+				r5l_recovery_reset_stripe(sh);
+				sh->log_start = ctx->pos;
+				list_move_tail(&sh->lru, cached_stripe_list);
+			}
+			r5l_recovery_load_data(log, sh, ctx, payload,
+					       log_offset);
+		} else if (payload->header.type == R5LOG_PAYLOAD_PARITY)
+			r5l_recovery_load_parity(log, sh, ctx, payload,
+						 log_offset);
+		else
+			return -EINVAL;
+
+		log_offset = r5l_ring_add(log, log_offset,
+					  le32_to_cpu(payload->size));
+
+		mb_offset += sizeof(struct r5l_payload_data_parity) +
+			sizeof(__le32) *
+			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+	}
+
+	return 0;
+}
+
+/*
+ * Load the stripe into cache. The stripe will be written out later by
+ * the stripe cache state machine.
+ */
+static void r5c_recovery_load_one_stripe(struct r5l_log *log,
+					 struct stripe_head *sh)
+{
+	struct r5conf *conf = sh->raid_conf;
+	struct r5dev *dev;
+	int i;
+
+	for (i = sh->disks; i--; ) {
+		dev = sh->dev + i;
+		if (test_and_clear_bit(R5_Wantwrite, &dev->flags)) {
+			set_bit(R5_InJournal, &dev->flags);
+			set_bit(R5_UPTODATE, &dev->flags);
+		}
+	}
+	set_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state);
+	atomic_inc(&conf->r5c_cached_partial_stripes);
+	list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
+}
+
+/*
+ * Scan through the log for all to-be-flushed data
+ *
+ * For stripes with data and parity, namely Data-Parity stripe
+ * (STRIPE_R5C_CACHING == 0), we simply replay all the writes.
+ *
+ * For stripes with only data, namely Data-Only stripe
+ * (STRIPE_R5C_CACHING == 1), we load them to stripe cache state machine.
+ *
+ * For a stripe, if we see data after parity, we should discard all previous
+ * data and parity for this stripe, as these data are already flushed to
+ * the array.
+ *
+ * At the end of the scan, we return the new journal_tail, which points to
+ * first data-only stripe on the journal device, or next invalid meta block.
+ */
+static int r5c_recovery_flush_log(struct r5l_log *log,
+				  struct r5l_recovery_ctx *ctx)
+{
+	struct stripe_head *sh, *next;
+	int ret = 0;
+
+	/* scan through the log */
+	while (1) {
+		if (r5l_recovery_read_meta_block(log, ctx))
+			break;
+
+		ret = r5c_recovery_analyze_meta_block(log, ctx,
+						      &ctx->cached_list);
+		/*
+		 * -EAGAIN means mismatch in data block, in this case, we still
+		 * try scan the next metablock
+		 */
+		if (ret && ret != -EAGAIN)
+			break;   /* ret == -EINVAL or -ENOMEM */
+		ctx->seq++;
+		ctx->pos = r5l_ring_add(log, ctx->pos, ctx->meta_total_blocks);
+	}
+
+	if (ret == -ENOMEM) {
+		r5c_recovery_drop_stripes(&ctx->cached_list, ctx);
+		return ret;
+	}
+
+	/* replay data-parity stripes */
+	r5c_recovery_replay_stripes(&ctx->cached_list, ctx);
+
+	/* load data-only stripes to stripe cache */
+	list_for_each_entry_safe(sh, next, &ctx->cached_list, lru) {
+		WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
+		r5c_recovery_load_one_stripe(log, sh);
+		list_del_init(&sh->lru);
+		raid5_release_stripe(sh);
+		ctx->data_only_stripes++;
+	}
+
+	return 0;
+}
+
+/*
+ * we did a recovery. Now ctx.pos points to an invalid meta block. New
+ * log will start here. but we can't let superblock point to last valid
+ * meta block. The log might looks like:
+ * | meta 1| meta 2| meta 3|
+ * meta 1 is valid, meta 2 is invalid. meta 3 could be valid. If
+ * superblock points to meta 1, we write a new valid meta 2n.  if crash
+ * happens again, new recovery will start from meta 1. Since meta 2n is
+ * valid now, recovery will think meta 3 is valid, which is wrong.
+ * The solution is we create a new meta in meta2 with its seq == meta
+ * 1's seq + 10 and let superblock points to meta2. The same recovery will
+ * not think meta 3 is a valid meta, because its seq doesn't match
+ */
+
+/*
+ * Before recovery, the log looks like the following
+ *
+ *   ---------------------------------------------
+ *   |           valid log        | invalid log  |
+ *   ---------------------------------------------
+ *   ^
+ *   |- log->last_checkpoint
+ *   |- log->last_cp_seq
+ *
+ * Now we scan through the log until we see invalid entry
+ *
+ *   ---------------------------------------------
+ *   |           valid log        | invalid log  |
+ *   ---------------------------------------------
+ *   ^                            ^
+ *   |- log->last_checkpoint      |- ctx->pos
+ *   |- log->last_cp_seq          |- ctx->seq
+ *
+ * From this point, we need to increase seq number by 10 to avoid
+ * confusing next recovery.
+ *
+ *   ---------------------------------------------
+ *   |           valid log        | invalid log  |
+ *   ---------------------------------------------
+ *   ^                              ^
+ *   |- log->last_checkpoint        |- ctx->pos+1
+ *   |- log->last_cp_seq            |- ctx->seq+11
+ *
+ * However, it is not safe to start the state machine yet, because data only
+ * parities are not yet secured in RAID. To save these data only parities, we
+ * rewrite them from seq+11.
+ *
+ *   -----------------------------------------------------------------
+ *   |           valid log        | data only stripes | invalid log  |
+ *   -----------------------------------------------------------------
+ *   ^                                                ^
+ *   |- log->last_checkpoint                          |- ctx->pos+n
+ *   |- log->last_cp_seq                              |- ctx->seq+10+n
+ *
+ * If failure happens again during this process, the recovery can safe start
+ * again from log->last_checkpoint.
+ *
+ * Once data only stripes are rewritten to journal, we move log_tail
+ *
+ *   -----------------------------------------------------------------
+ *   |     old log        |    data only stripes    | invalid log  |
+ *   -----------------------------------------------------------------
+ *                        ^                         ^
+ *                        |- log->last_checkpoint   |- ctx->pos+n
+ *                        |- log->last_cp_seq       |- ctx->seq+10+n
+ *
+ * Then we can safely start the state machine. If failure happens from this
+ * point on, the recovery will start from new log->last_checkpoint.
+ */
+static int
+r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
+				       struct r5l_recovery_ctx *ctx)
+{
+	struct stripe_head *sh;
+	struct mddev *mddev = log->rdev->mddev;
+	struct page *page;
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page) {
+		pr_err("md/raid:%s: cannot allocate memory to rewrite data only stripes\n",
+		       mdname(mddev));
+		return -ENOMEM;
+	}
+
+	ctx->seq += 10;
+	list_for_each_entry(sh, &ctx->cached_list, lru) {
+		struct r5l_meta_block *mb;
+		int i;
+		int offset;
+		sector_t write_pos;
+
+		WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
+		r5l_recovery_create_empty_meta_block(log, page,
+						     ctx->pos, ctx->seq);
+		mb = page_address(page);
+		offset = le32_to_cpu(mb->meta_size);
+		write_pos = ctx->pos + BLOCK_SECTORS;
+
+		for (i = sh->disks; i--; ) {
+			struct r5dev *dev = &sh->dev[i];
+			struct r5l_payload_data_parity *payload;
+			void *addr;
+
+			if (test_bit(R5_InJournal, &dev->flags)) {
+				payload = (void *)mb + offset;
+				payload->header.type = cpu_to_le16(
+					R5LOG_PAYLOAD_DATA);
+				payload->size = BLOCK_SECTORS;
+				payload->location = cpu_to_le64(
+					raid5_compute_blocknr(sh, i, 0));
+				addr = kmap_atomic(dev->page);
+				payload->checksum[0] = cpu_to_le32(
+					crc32c_le(log->uuid_checksum, addr,
+						  PAGE_SIZE));
+				kunmap_atomic(addr);
+				sync_page_io(log->rdev, write_pos, PAGE_SIZE,
+					     dev->page, REQ_OP_WRITE, 0, false);
+				write_pos = r5l_ring_add(log, write_pos,
+							 BLOCK_SECTORS);
+				offset += sizeof(__le32) +
+					sizeof(struct r5l_payload_data_parity);
+
+			}
+		}
+		mb->meta_size = cpu_to_le32(offset);
+		mb->checksum = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
+		sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,
+			     REQ_OP_WRITE, WRITE_FUA, false);
+		sh->log_start = ctx->pos;
+		ctx->pos = write_pos;
+		ctx->seq += 1;
+	}
+	__free_page(page);
+	return 0;
+}
+
 static int r5l_recovery_log(struct r5l_log *log)
 {
 	struct r5l_recovery_ctx ctx;
@@ -1583,6 +2171,10 @@ static int r5l_recovery_log(struct r5l_log *log)
 	ctx.pos = log->last_checkpoint;
 	ctx.seq = log->last_cp_seq;
 	ctx.meta_page = alloc_page(GFP_KERNEL);
+	ctx.data_only_stripes = 0;
+	ctx.data_parity_stripes = 0;
+	INIT_LIST_HEAD(&ctx.cached_list);
+
 	if (!ctx.meta_page)
 		return -ENOMEM;
 
@@ -1617,6 +2209,16 @@ static int r5l_recovery_log(struct r5l_log *log)
 		log->log_start = ctx.pos;
 		log->seq = ctx.seq;
 	}
+
+	/*
+	 * This is to suppress "function defined but not used" warning.
+	 * It will be removed when the two functions are used (next patch).
+	 */
+	if (!log) {
+		r5c_recovery_flush_log(log, &ctx);
+		r5c_recovery_rewrite_data_only_stripes(log, &ctx);
+	}
+
 	return 0;
 }