Merge branch 'x15-audio-fixes' into omap-for-v4.4/fixes

1 files changed, 1191 insertions, 0 deletions

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
new file mode 100644
index 000000000000..b887e04d7e5c
--- /dev/null
+++ b/drivers/md/raid5-cache.c
@@ -0,0 +1,1191 @@
+/*
+ * Copyright (C) 2015 Shaohua Li <shli@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,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/wait.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/raid/md_p.h>
+#include <linux/crc32c.h>
+#include <linux/random.h>
+#include "md.h"
+#include "raid5.h"
+
+/*
+ * metadata/data stored in disk with 4k size unit (a block) regardless
+ * underneath hardware sector size. only works with PAGE_SIZE == 4096
+ */
+#define BLOCK_SECTORS (8)
+
+/*
+ * reclaim runs every 1/4 disk size or 10G reclaimable space. This can prevent
+ * recovery scans a very long log
+ */
+#define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
+#define RECLAIM_MAX_FREE_SPACE_SHIFT (2)
+
+struct r5l_log {
+	struct md_rdev *rdev;
+
+	u32 uuid_checksum;
+
+	sector_t device_size;		/* log device size, round to
+					 * BLOCK_SECTORS */
+	sector_t max_free_space;	/* reclaim run if free space is at
+					 * this size */
+
+	sector_t last_checkpoint;	/* log tail. where recovery scan
+					 * starts from */
+	u64 last_cp_seq;		/* log tail sequence */
+
+	sector_t log_start;		/* log head. where new data appends */
+	u64 seq;			/* log head sequence */
+
+	sector_t next_checkpoint;
+	u64 next_cp_seq;
+
+	struct mutex io_mutex;
+	struct r5l_io_unit *current_io;	/* current io_unit accepting new data */
+
+	spinlock_t io_list_lock;
+	struct list_head running_ios;	/* io_units which are still running,
+					 * and have not yet been completely
+					 * written to the log */
+	struct list_head io_end_ios;	/* io_units which have been completely
+					 * written to the log but not yet written
+					 * to the RAID */
+	struct list_head flushing_ios;	/* io_units which are waiting for log
+					 * cache flush */
+	struct list_head finished_ios;	/* io_units which settle down in log disk */
+	struct bio flush_bio;
+
+	struct kmem_cache *io_kc;
+
+	struct md_thread *reclaim_thread;
+	unsigned long reclaim_target;	/* number of space that need to be
+					 * reclaimed.  if it's 0, reclaim spaces
+					 * used by io_units which are in
+					 * IO_UNIT_STRIPE_END state (eg, reclaim
+					 * dones't wait for specific io_unit
+					 * switching to IO_UNIT_STRIPE_END
+					 * state) */
+	wait_queue_head_t iounit_wait;
+
+	struct list_head no_space_stripes; /* pending stripes, log has no space */
+	spinlock_t no_space_stripes_lock;
+
+	bool need_cache_flush;
+	bool in_teardown;
+};
+
+/*
+ * an IO range starts from a meta data block and end at the next meta data
+ * block. The io unit's the meta data block tracks data/parity followed it. io
+ * unit is written to log disk with normal write, as we always flush log disk
+ * first and then start move data to raid disks, there is no requirement to
+ * write io unit with FLUSH/FUA
+ */
+struct r5l_io_unit {
+	struct r5l_log *log;
+
+	struct page *meta_page;	/* store meta block */
+	int meta_offset;	/* current offset in meta_page */
+
+	struct bio *current_bio;/* current_bio accepting new data */
+
+	atomic_t pending_stripe;/* how many stripes not flushed to raid */
+	u64 seq;		/* seq number of the metablock */
+	sector_t log_start;	/* where the io_unit starts */
+	sector_t log_end;	/* where the io_unit ends */
+	struct list_head log_sibling; /* log->running_ios */
+	struct list_head stripe_list; /* stripes added to the io_unit */
+
+	int state;
+	bool need_split_bio;
+};
+
+/* r5l_io_unit state */
+enum r5l_io_unit_state {
+	IO_UNIT_RUNNING = 0,	/* accepting new IO */
+	IO_UNIT_IO_START = 1,	/* io_unit bio start writing to log,
+				 * don't accepting new bio */
+	IO_UNIT_IO_END = 2,	/* io_unit bio finish writing to log */
+	IO_UNIT_STRIPE_END = 3,	/* stripes data finished writing to raid */
+};
+
+static sector_t r5l_ring_add(struct r5l_log *log, sector_t start, sector_t inc)
+{
+	start += inc;
+	if (start >= log->device_size)
+		start = start - log->device_size;
+	return start;
+}
+
+static sector_t r5l_ring_distance(struct r5l_log *log, sector_t start,
+				  sector_t end)
+{
+	if (end >= start)
+		return end - start;
+	else
+		return end + log->device_size - start;
+}
+
+static bool r5l_has_free_space(struct r5l_log *log, sector_t size)
+{
+	sector_t used_size;
+
+	used_size = r5l_ring_distance(log, log->last_checkpoint,
+					log->log_start);
+
+	return log->device_size > used_size + size;
+}
+
+static void r5l_free_io_unit(struct r5l_log *log, struct r5l_io_unit *io)
+{
+	__free_page(io->meta_page);
+	kmem_cache_free(log->io_kc, io);
+}
+
+static void r5l_move_io_unit_list(struct list_head *from, struct list_head *to,
+				  enum r5l_io_unit_state state)
+{
+	struct r5l_io_unit *io;
+
+	while (!list_empty(from)) {
+		io = list_first_entry(from, struct r5l_io_unit, log_sibling);
+		/* don't change list order */
+		if (io->state >= state)
+			list_move_tail(&io->log_sibling, to);
+		else
+			break;
+	}
+}
+
+static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
+				    enum r5l_io_unit_state state)
+{
+	if (WARN_ON(io->state >= state))
+		return;
+	io->state = state;
+}
+
+static void r5l_io_run_stripes(struct r5l_io_unit *io)
+{
+	struct stripe_head *sh, *next;
+
+	list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
+		list_del_init(&sh->log_list);
+		set_bit(STRIPE_HANDLE, &sh->state);
+		raid5_release_stripe(sh);
+	}
+}
+
+static void r5l_log_run_stripes(struct r5l_log *log)
+{
+	struct r5l_io_unit *io, *next;
+
+	assert_spin_locked(&log->io_list_lock);
+
+	list_for_each_entry_safe(io, next, &log->running_ios, log_sibling) {
+		/* don't change list order */
+		if (io->state < IO_UNIT_IO_END)
+			break;
+
+		list_move_tail(&io->log_sibling, &log->finished_ios);
+		r5l_io_run_stripes(io);
+	}
+}
+
+static void r5l_log_endio(struct bio *bio)
+{
+	struct r5l_io_unit *io = bio->bi_private;
+	struct r5l_log *log = io->log;
+	unsigned long flags;
+
+	if (bio->bi_error)
+		md_error(log->rdev->mddev, log->rdev);
+
+	bio_put(bio);
+
+	spin_lock_irqsave(&log->io_list_lock, flags);
+	__r5l_set_io_unit_state(io, IO_UNIT_IO_END);
+	if (log->need_cache_flush)
+		r5l_move_io_unit_list(&log->running_ios, &log->io_end_ios,
+				      IO_UNIT_IO_END);
+	else
+		r5l_log_run_stripes(log);
+	spin_unlock_irqrestore(&log->io_list_lock, flags);
+
+	if (log->need_cache_flush)
+		md_wakeup_thread(log->rdev->mddev->thread);
+}
+
+static void r5l_submit_current_io(struct r5l_log *log)
+{
+	struct r5l_io_unit *io = log->current_io;
+	struct r5l_meta_block *block;
+	unsigned long flags;
+	u32 crc;
+
+	if (!io)
+		return;
+
+	block = page_address(io->meta_page);
+	block->meta_size = cpu_to_le32(io->meta_offset);
+	crc = crc32c_le(log->uuid_checksum, block, PAGE_SIZE);
+	block->checksum = cpu_to_le32(crc);
+
+	log->current_io = NULL;
+	spin_lock_irqsave(&log->io_list_lock, flags);
+	__r5l_set_io_unit_state(io, IO_UNIT_IO_START);
+	spin_unlock_irqrestore(&log->io_list_lock, flags);
+
+	submit_bio(WRITE, io->current_bio);
+}
+
+static struct bio *r5l_bio_alloc(struct r5l_log *log)
+{
+	struct bio *bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL, BIO_MAX_PAGES);
+
+	bio->bi_rw = WRITE;
+	bio->bi_bdev = log->rdev->bdev;
+	bio->bi_iter.bi_sector = log->rdev->data_offset + log->log_start;
+
+	return bio;
+}
+
+static void r5_reserve_log_entry(struct r5l_log *log, struct r5l_io_unit *io)
+{
+	log->log_start = r5l_ring_add(log, log->log_start, BLOCK_SECTORS);
+
+	/*
+	 * If we filled up the log device start from the beginning again,
+	 * which will require a new bio.
+	 *
+	 * Note: for this to work properly the log size needs to me a multiple
+	 * of BLOCK_SECTORS.
+	 */
+	if (log->log_start == 0)
+		io->need_split_bio = true;
+
+	io->log_end = log->log_start;
+}
+
+static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
+{
+	struct r5l_io_unit *io;
+	struct r5l_meta_block *block;
+
+	/* We can't handle memory allocate failure so far */
+	io = kmem_cache_zalloc(log->io_kc, GFP_NOIO | __GFP_NOFAIL);
+	io->log = log;
+	INIT_LIST_HEAD(&io->log_sibling);
+	INIT_LIST_HEAD(&io->stripe_list);
+	io->state = IO_UNIT_RUNNING;
+
+	io->meta_page = alloc_page(GFP_NOIO | __GFP_NOFAIL | __GFP_ZERO);
+	block = page_address(io->meta_page);
+	block->magic = cpu_to_le32(R5LOG_MAGIC);
+	block->version = R5LOG_VERSION;
+	block->seq = cpu_to_le64(log->seq);
+	block->position = cpu_to_le64(log->log_start);
+
+	io->log_start = log->log_start;
+	io->meta_offset = sizeof(struct r5l_meta_block);
+	io->seq = log->seq++;
+
+	io->current_bio = r5l_bio_alloc(log);
+	io->current_bio->bi_end_io = r5l_log_endio;
+	io->current_bio->bi_private = io;
+	bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
+
+	r5_reserve_log_entry(log, io);
+
+	spin_lock_irq(&log->io_list_lock);
+	list_add_tail(&io->log_sibling, &log->running_ios);
+	spin_unlock_irq(&log->io_list_lock);
+
+	return io;
+}
+
+static int r5l_get_meta(struct r5l_log *log, unsigned int payload_size)
+{
+	if (log->current_io &&
+	    log->current_io->meta_offset + payload_size > PAGE_SIZE)
+		r5l_submit_current_io(log);
+
+	if (!log->current_io)
+		log->current_io = r5l_new_meta(log);
+	return 0;
+}
+
+static void r5l_append_payload_meta(struct r5l_log *log, u16 type,
+				    sector_t location,
+				    u32 checksum1, u32 checksum2,
+				    bool checksum2_valid)
+{
+	struct r5l_io_unit *io = log->current_io;
+	struct r5l_payload_data_parity *payload;
+
+	payload = page_address(io->meta_page) + io->meta_offset;
+	payload->header.type = cpu_to_le16(type);
+	payload->header.flags = cpu_to_le16(0);
+	payload->size = cpu_to_le32((1 + !!checksum2_valid) <<
+				    (PAGE_SHIFT - 9));
+	payload->location = cpu_to_le64(location);
+	payload->checksum[0] = cpu_to_le32(checksum1);
+	if (checksum2_valid)
+		payload->checksum[1] = cpu_to_le32(checksum2);
+
+	io->meta_offset += sizeof(struct r5l_payload_data_parity) +
+		sizeof(__le32) * (1 + !!checksum2_valid);
+}
+
+static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
+{
+	struct r5l_io_unit *io = log->current_io;
+
+	if (io->need_split_bio) {
+		struct bio *prev = io->current_bio;
+
+		io->current_bio = r5l_bio_alloc(log);
+		bio_chain(io->current_bio, prev);
+
+		submit_bio(WRITE, prev);
+	}
+
+	if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0))
+		BUG();
+
+	r5_reserve_log_entry(log, io);
+}
+
+static void r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
+			   int data_pages, int parity_pages)
+{
+	int i;
+	int meta_size;
+	struct r5l_io_unit *io;
+
+	meta_size =
+		((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
+		 * data_pages) +
+		sizeof(struct r5l_payload_data_parity) +
+		sizeof(__le32) * parity_pages;
+
+	r5l_get_meta(log, meta_size);
+	io = log->current_io;
+
+	for (i = 0; i < sh->disks; i++) {
+		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
+			continue;
+		if (i == sh->pd_idx || i == sh->qd_idx)
+			continue;
+		r5l_append_payload_meta(log, R5LOG_PAYLOAD_DATA,
+					raid5_compute_blocknr(sh, i, 0),
+					sh->dev[i].log_checksum, 0, false);
+		r5l_append_payload_page(log, sh->dev[i].page);
+	}
+
+	if (sh->qd_idx >= 0) {
+		r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
+					sh->sector, sh->dev[sh->pd_idx].log_checksum,
+					sh->dev[sh->qd_idx].log_checksum, true);
+		r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
+		r5l_append_payload_page(log, sh->dev[sh->qd_idx].page);
+	} else {
+		r5l_append_payload_meta(log, R5LOG_PAYLOAD_PARITY,
+					sh->sector, sh->dev[sh->pd_idx].log_checksum,
+					0, false);
+		r5l_append_payload_page(log, sh->dev[sh->pd_idx].page);
+	}
+
+	list_add_tail(&sh->log_list, &io->stripe_list);
+	atomic_inc(&io->pending_stripe);
+	sh->log_io = io;
+}
+
+static void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
+/*
+ * running in raid5d, where reclaim could wait for raid5d too (when it flushes
+ * data from log to raid disks), so we shouldn't wait for reclaim here
+ */
+int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
+{
+	int write_disks = 0;
+	int data_pages, parity_pages;
+	int meta_size;
+	int reserve;
+	int i;
+
+	if (!log)
+		return -EAGAIN;
+	/* Don't support stripe batch */
+	if (sh->log_io || !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
+	    test_bit(STRIPE_SYNCING, &sh->state)) {
+		/* the stripe is written to log, we start writing it to raid */
+		clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
+		return -EAGAIN;
+	}
+
+	for (i = 0; i < sh->disks; i++) {
+		void *addr;
+
+		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
+			continue;
+		write_disks++;
+		/* checksum is already calculated in last run */
+		if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
+			continue;
+		addr = kmap_atomic(sh->dev[i].page);
+		sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
+						    addr, PAGE_SIZE);
+		kunmap_atomic(addr);
+	}
+	parity_pages = 1 + !!(sh->qd_idx >= 0);
+	data_pages = write_disks - parity_pages;
+
+	meta_size =
+		((sizeof(struct r5l_payload_data_parity) + sizeof(__le32))
+		 * data_pages) +
+		sizeof(struct r5l_payload_data_parity) +
+		sizeof(__le32) * parity_pages;
+	/* Doesn't work with very big raid array */
+	if (meta_size + sizeof(struct r5l_meta_block) > PAGE_SIZE)
+		return -EINVAL;
+
+	set_bit(STRIPE_LOG_TRAPPED, &sh->state);
+	/*
+	 * The stripe must enter state machine again to finish the write, so
+	 * don't delay.
+	 */
+	clear_bit(STRIPE_DELAYED, &sh->state);
+	atomic_inc(&sh->count);
+
+	mutex_lock(&log->io_mutex);
+	/* meta + data */
+	reserve = (1 + write_disks) << (PAGE_SHIFT - 9);
+	if (r5l_has_free_space(log, reserve))
+		r5l_log_stripe(log, sh, data_pages, parity_pages);
+	else {
+		spin_lock(&log->no_space_stripes_lock);
+		list_add_tail(&sh->log_list, &log->no_space_stripes);
+		spin_unlock(&log->no_space_stripes_lock);
+
+		r5l_wake_reclaim(log, reserve);
+	}
+	mutex_unlock(&log->io_mutex);
+
+	return 0;
+}
+
+void r5l_write_stripe_run(struct r5l_log *log)
+{
+	if (!log)
+		return;
+	mutex_lock(&log->io_mutex);
+	r5l_submit_current_io(log);
+	mutex_unlock(&log->io_mutex);
+}
+
+int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio)
+{
+	if (!log)
+		return -ENODEV;
+	/*
+	 * we flush log disk cache first, then write stripe data to raid disks.
+	 * So if bio is finished, the log disk cache is flushed already. The
+	 * recovery guarantees we can recovery the bio from log disk, so we
+	 * don't need to flush again
+	 */
+	if (bio->bi_iter.bi_size == 0) {
+		bio_endio(bio);
+		return 0;
+	}
+	bio->bi_rw &= ~REQ_FLUSH;
+	return -EAGAIN;
+}
+
+/* This will run after log space is reclaimed */
+static void r5l_run_no_space_stripes(struct r5l_log *log)
+{
+	struct stripe_head *sh;
+
+	spin_lock(&log->no_space_stripes_lock);
+	while (!list_empty(&log->no_space_stripes)) {
+		sh = list_first_entry(&log->no_space_stripes,
+				      struct stripe_head, log_list);
+		list_del_init(&sh->log_list);
+		set_bit(STRIPE_HANDLE, &sh->state);
+		raid5_release_stripe(sh);
+	}
+	spin_unlock(&log->no_space_stripes_lock);
+}
+
+static sector_t r5l_reclaimable_space(struct r5l_log *log)
+{
+	return r5l_ring_distance(log, log->last_checkpoint,
+				 log->next_checkpoint);
+}
+
+static bool r5l_complete_finished_ios(struct r5l_log *log)
+{
+	struct r5l_io_unit *io, *next;
+	bool found = false;
+
+	assert_spin_locked(&log->io_list_lock);
+
+	list_for_each_entry_safe(io, next, &log->finished_ios, log_sibling) {
+		/* don't change list order */
+		if (io->state < IO_UNIT_STRIPE_END)
+			break;
+
+		log->next_checkpoint = io->log_start;
+		log->next_cp_seq = io->seq;
+
+		list_del(&io->log_sibling);
+		r5l_free_io_unit(log, io);
+
+		found = true;
+	}
+
+	return found;
+}
+
+static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
+{
+	struct r5l_log *log = io->log;
+	unsigned long flags;
+
+	spin_lock_irqsave(&log->io_list_lock, flags);
+	__r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
+
+	if (!r5l_complete_finished_ios(log)) {
+		spin_unlock_irqrestore(&log->io_list_lock, flags);
+		return;
+	}
+
+	if (r5l_reclaimable_space(log) > log->max_free_space)
+		r5l_wake_reclaim(log, 0);
+
+	spin_unlock_irqrestore(&log->io_list_lock, flags);
+	wake_up(&log->iounit_wait);
+}
+
+void r5l_stripe_write_finished(struct stripe_head *sh)
+{
+	struct r5l_io_unit *io;
+
+	io = sh->log_io;
+	sh->log_io = NULL;
+
+	if (io && atomic_dec_and_test(&io->pending_stripe))
+		__r5l_stripe_write_finished(io);
+}
+
+static void r5l_log_flush_endio(struct bio *bio)
+{
+	struct r5l_log *log = container_of(bio, struct r5l_log,
+		flush_bio);
+	unsigned long flags;
+	struct r5l_io_unit *io;
+
+	if (bio->bi_error)
+		md_error(log->rdev->mddev, log->rdev);
+
+	spin_lock_irqsave(&log->io_list_lock, flags);
+	list_for_each_entry(io, &log->flushing_ios, log_sibling)
+		r5l_io_run_stripes(io);
+	list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
+	spin_unlock_irqrestore(&log->io_list_lock, flags);
+}
+
+/*
+ * Starting dispatch IO to raid.
+ * io_unit(meta) consists of a log. There is one situation we want to avoid. A
+ * broken meta in the middle of a log causes recovery can't find meta at the
+ * head of log. If operations require meta at the head persistent in log, we
+ * must make sure meta before it persistent in log too. A case is:
+ *
+ * stripe data/parity is in log, we start write stripe to raid disks. stripe
+ * data/parity must be persistent in log before we do the write to raid disks.
+ *
+ * The solution is we restrictly maintain io_unit list order. In this case, we
+ * only write stripes of an io_unit to raid disks till the io_unit is the first
+ * one whose data/parity is in log.
+ */
+void r5l_flush_stripe_to_raid(struct r5l_log *log)
+{
+	bool do_flush;
+
+	if (!log || !log->need_cache_flush)
+		return;
+
+	spin_lock_irq(&log->io_list_lock);
+	/* flush bio is running */
+	if (!list_empty(&log->flushing_ios)) {
+		spin_unlock_irq(&log->io_list_lock);
+		return;
+	}
+	list_splice_tail_init(&log->io_end_ios, &log->flushing_ios);
+	do_flush = !list_empty(&log->flushing_ios);
+	spin_unlock_irq(&log->io_list_lock);
+
+	if (!do_flush)
+		return;
+	bio_reset(&log->flush_bio);
+	log->flush_bio.bi_bdev = log->rdev->bdev;
+	log->flush_bio.bi_end_io = r5l_log_flush_endio;
+	submit_bio(WRITE_FLUSH, &log->flush_bio);
+}
+
+static void r5l_write_super(struct r5l_log *log, sector_t cp);
+static void r5l_write_super_and_discard_space(struct r5l_log *log,
+	sector_t end)
+{
+	struct block_device *bdev = log->rdev->bdev;
+	struct mddev *mddev;
+
+	r5l_write_super(log, end);
+
+	if (!blk_queue_discard(bdev_get_queue(bdev)))
+		return;
+
+	mddev = log->rdev->mddev;
+	/*
+	 * This is to avoid a deadlock. r5l_quiesce holds reconfig_mutex and
+	 * wait for this thread to finish. This thread waits for
+	 * MD_CHANGE_PENDING clear, which is supposed to be done in
+	 * md_check_recovery(). md_check_recovery() tries to get
+	 * reconfig_mutex. Since r5l_quiesce already holds the mutex,
+	 * md_check_recovery() fails, so the PENDING never get cleared. The
+	 * in_teardown check workaround this issue.
+	 */
+	if (!log->in_teardown) {
+		set_bit(MD_CHANGE_DEVS, &mddev->flags);
+		set_bit(MD_CHANGE_PENDING, &mddev->flags);
+		md_wakeup_thread(mddev->thread);
+		wait_event(mddev->sb_wait,
+			!test_bit(MD_CHANGE_PENDING, &mddev->flags) ||
+			log->in_teardown);
+		/*
+		 * r5l_quiesce could run after in_teardown check and hold
+		 * mutex first. Superblock might get updated twice.
+		 */
+		if (log->in_teardown)
+			md_update_sb(mddev, 1);
+	} else {
+		WARN_ON(!mddev_is_locked(mddev));
+		md_update_sb(mddev, 1);
+	}
+
+	/* discard IO error really doesn't matter, ignore it */
+	if (log->last_checkpoint < end) {
+		blkdev_issue_discard(bdev,
+				log->last_checkpoint + log->rdev->data_offset,
+				end - log->last_checkpoint, GFP_NOIO, 0);
+	} else {
+		blkdev_issue_discard(bdev,
+				log->last_checkpoint + log->rdev->data_offset,
+				log->device_size - log->last_checkpoint,
+				GFP_NOIO, 0);
+		blkdev_issue_discard(bdev, log->rdev->data_offset, end,
+				GFP_NOIO, 0);
+	}
+}
+
+
+static void r5l_do_reclaim(struct r5l_log *log)
+{
+	sector_t reclaim_target = xchg(&log->reclaim_target, 0);
+	sector_t reclaimable;
+	sector_t next_checkpoint;
+	u64 next_cp_seq;
+
+	spin_lock_irq(&log->io_list_lock);
+	/*
+	 * move proper io_unit to reclaim list. We should not change the order.
+	 * reclaimable/unreclaimable io_unit can be mixed in the list, we
+	 * shouldn't reuse space of an unreclaimable io_unit
+	 */
+	while (1) {
+		reclaimable = r5l_reclaimable_space(log);
+		if (reclaimable >= reclaim_target ||
+		    (list_empty(&log->running_ios) &&
+		     list_empty(&log->io_end_ios) &&
+		     list_empty(&log->flushing_ios) &&
+		     list_empty(&log->finished_ios)))
+			break;
+
+		md_wakeup_thread(log->rdev->mddev->thread);
+		wait_event_lock_irq(log->iounit_wait,
+				    r5l_reclaimable_space(log) > reclaimable,
+				    log->io_list_lock);
+	}
+
+	next_checkpoint = log->next_checkpoint;
+	next_cp_seq = log->next_cp_seq;
+	spin_unlock_irq(&log->io_list_lock);
+
+	BUG_ON(reclaimable < 0);
+	if (reclaimable == 0)
+		return;
+
+	/*
+	 * write_super will flush cache of each raid disk. We must write super
+	 * here, because the log area might be reused soon and we don't want to
+	 * confuse recovery
+	 */
+	r5l_write_super_and_discard_space(log, next_checkpoint);
+
+	mutex_lock(&log->io_mutex);
+	log->last_checkpoint = next_checkpoint;
+	log->last_cp_seq = next_cp_seq;
+	mutex_unlock(&log->io_mutex);
+
+	r5l_run_no_space_stripes(log);
+}
+
+static void r5l_reclaim_thread(struct md_thread *thread)
+{
+	struct mddev *mddev = thread->mddev;
+	struct r5conf *conf = mddev->private;
+	struct r5l_log *log = conf->log;
+
+	if (!log)
+		return;
+	r5l_do_reclaim(log);
+}
+
+static void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
+{
+	unsigned long target;
+	unsigned long new = (unsigned long)space; /* overflow in theory */
+
+	do {
+		target = log->reclaim_target;
+		if (new < target)
+			return;
+	} while (cmpxchg(&log->reclaim_target, target, new) != target);
+	md_wakeup_thread(log->reclaim_thread);
+}
+
+void r5l_quiesce(struct r5l_log *log, int state)
+{
+	struct mddev *mddev;
+	if (!log || state == 2)
+		return;
+	if (state == 0) {
+		log->in_teardown = 0;
+		log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
+					log->rdev->mddev, "reclaim");
+	} else if (state == 1) {
+		/*
+		 * at this point all stripes are finished, so io_unit is at
+		 * least in STRIPE_END state
+		 */
+		log->in_teardown = 1;
+		/* make sure r5l_write_super_and_discard_space exits */
+		mddev = log->rdev->mddev;
+		wake_up(&mddev->sb_wait);
+		r5l_wake_reclaim(log, -1L);
+		md_unregister_thread(&log->reclaim_thread);
+		r5l_do_reclaim(log);
+	}
+}
+
+bool r5l_log_disk_error(struct r5conf *conf)
+{
+	/* don't allow write if journal disk is missing */
+	if (!conf->log)
+		return test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
+	return test_bit(Faulty, &conf->log->rdev->flags);
+}
+
+struct r5l_recovery_ctx {
+	struct page *meta_page;		/* current meta */
+	sector_t meta_total_blocks;	/* total size of current meta and data */
+	sector_t pos;			/* recovery position */
+	u64 seq;			/* recovery position seq */
+};
+
+static int r5l_read_meta_block(struct r5l_log *log,
+			       struct r5l_recovery_ctx *ctx)
+{
+	struct page *page = ctx->meta_page;
+	struct r5l_meta_block *mb;
+	u32 crc, stored_crc;
+
+	if (!sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page, READ, false))
+		return -EIO;
+
+	mb = page_address(page);
+	stored_crc = le32_to_cpu(mb->checksum);
+	mb->checksum = 0;
+
+	if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
+	    le64_to_cpu(mb->seq) != ctx->seq ||
+	    mb->version != R5LOG_VERSION ||
+	    le64_to_cpu(mb->position) != ctx->pos)
+		return -EINVAL;
+
+	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
+	if (stored_crc != crc)
+		return -EINVAL;
+
+	if (le32_to_cpu(mb->meta_size) > PAGE_SIZE)
+		return -EINVAL;
+
+	ctx->meta_total_blocks = BLOCK_SECTORS;
+
+	return 0;
+}
+
+static int r5l_recovery_flush_one_stripe(struct r5l_log *log,
+					 struct r5l_recovery_ctx *ctx,
+					 sector_t stripe_sect,
+					 int *offset, sector_t *log_offset)
+{
+	struct r5conf *conf = log->rdev->mddev->private;
+	struct stripe_head *sh;
+	struct r5l_payload_data_parity *payload;
+	int disk_index;
+
+	sh = raid5_get_active_stripe(conf, stripe_sect, 0, 0, 0);
+	while (1) {
+		payload = page_address(ctx->meta_page) + *offset;
+
+		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_DATA) {
+			raid5_compute_sector(conf,
+					     le64_to_cpu(payload->location), 0,
+					     &disk_index, sh);
+
+			sync_page_io(log->rdev, *log_offset, PAGE_SIZE,
+				     sh->dev[disk_index].page, READ, false);
+			sh->dev[disk_index].log_checksum =
+				le32_to_cpu(payload->checksum[0]);
+			set_bit(R5_Wantwrite, &sh->dev[disk_index].flags);
+			ctx->meta_total_blocks += BLOCK_SECTORS;
+		} else {
+			disk_index = sh->pd_idx;
+			sync_page_io(log->rdev, *log_offset, PAGE_SIZE,
+				     sh->dev[disk_index].page, READ, false);
+			sh->dev[disk_index].log_checksum =
+				le32_to_cpu(payload->checksum[0]);
+			set_bit(R5_Wantwrite, &sh->dev[disk_index].flags);
+
+			if (sh->qd_idx >= 0) {
+				disk_index = sh->qd_idx;
+				sync_page_io(log->rdev,
+					     r5l_ring_add(log, *log_offset, BLOCK_SECTORS),
+					     PAGE_SIZE, sh->dev[disk_index].page,
+					     READ, false);
+				sh->dev[disk_index].log_checksum =
+					le32_to_cpu(payload->checksum[1]);
+				set_bit(R5_Wantwrite,
+					&sh->dev[disk_index].flags);
+			}
+			ctx->meta_total_blocks += BLOCK_SECTORS * conf->max_degraded;
+		}
+
+		*log_offset = r5l_ring_add(log, *log_offset,
+					   le32_to_cpu(payload->size));
+		*offset += sizeof(struct r5l_payload_data_parity) +
+			sizeof(__le32) *
+			(le32_to_cpu(payload->size) >> (PAGE_SHIFT - 9));
+		if (le16_to_cpu(payload->header.type) == R5LOG_PAYLOAD_PARITY)
+			break;
+	}
+
+	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
+		void *addr;
+		u32 checksum;
+
+		if (!test_bit(R5_Wantwrite, &sh->dev[disk_index].flags))
+			continue;
+		addr = kmap_atomic(sh->dev[disk_index].page);
+		checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
+		kunmap_atomic(addr);
+		if (checksum != sh->dev[disk_index].log_checksum)
+			goto error;
+	}
+
+	for (disk_index = 0; disk_index < sh->disks; disk_index++) {
+		struct md_rdev *rdev, *rrdev;
+
+		if (!test_and_clear_bit(R5_Wantwrite,
+					&sh->dev[disk_index].flags))
+			continue;
+
+		/* in case device is broken */
+		rdev = rcu_dereference(conf->disks[disk_index].rdev);
+		if (rdev)
+			sync_page_io(rdev, stripe_sect, PAGE_SIZE,
+				     sh->dev[disk_index].page, WRITE, false);
+		rrdev = rcu_dereference(conf->disks[disk_index].replacement);
+		if (rrdev)
+			sync_page_io(rrdev, stripe_sect, PAGE_SIZE,
+				     sh->dev[disk_index].page, WRITE, false);
+	}
+	raid5_release_stripe(sh);
+	return 0;
+
+error:
+	for (disk_index = 0; disk_index < sh->disks; disk_index++)
+		sh->dev[disk_index].flags = 0;
+	raid5_release_stripe(sh);
+	return -EINVAL;
+}
+
+static int r5l_recovery_flush_one_meta(struct r5l_log *log,
+				       struct r5l_recovery_ctx *ctx)
+{
+	struct r5conf *conf = log->rdev->mddev->private;
+	struct r5l_payload_data_parity *payload;
+	struct r5l_meta_block *mb;
+	int offset;
+	sector_t log_offset;
+	sector_t stripe_sector;
+
+	mb = page_address(ctx->meta_page);
+	offset = sizeof(struct r5l_meta_block);
+	log_offset = r5l_ring_add(log, ctx->pos, BLOCK_SECTORS);
+
+	while (offset < le32_to_cpu(mb->meta_size)) {
+		int dd;
+
+		payload = (void *)mb + offset;
+		stripe_sector = raid5_compute_sector(conf,
+						     le64_to_cpu(payload->location), 0, &dd, NULL);
+		if (r5l_recovery_flush_one_stripe(log, ctx, stripe_sector,
+						  &offset, &log_offset))
+			return -EINVAL;
+	}
+	return 0;
+}
+
+/* copy data/parity from log to raid disks */
+static void r5l_recovery_flush_log(struct r5l_log *log,
+				   struct r5l_recovery_ctx *ctx)
+{
+	while (1) {
+		if (r5l_read_meta_block(log, ctx))
+			return;
+		if (r5l_recovery_flush_one_meta(log, ctx))
+			return;
+		ctx->seq++;
+		ctx->pos = r5l_ring_add(log, ctx->pos, ctx->meta_total_blocks);
+	}
+}
+
+static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
+					  u64 seq)
+{
+	struct page *page;
+	struct r5l_meta_block *mb;
+	u32 crc;
+
+	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	if (!page)
+		return -ENOMEM;
+	mb = page_address(page);
+	mb->magic = cpu_to_le32(R5LOG_MAGIC);
+	mb->version = R5LOG_VERSION;
+	mb->meta_size = cpu_to_le32(sizeof(struct r5l_meta_block));
+	mb->seq = cpu_to_le64(seq);
+	mb->position = cpu_to_le64(pos);
+	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
+	mb->checksum = cpu_to_le32(crc);
+
+	if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, WRITE_FUA, false)) {
+		__free_page(page);
+		return -EIO;
+	}
+	__free_page(page);
+	return 0;
+}
+
+static int r5l_recovery_log(struct r5l_log *log)
+{
+	struct r5l_recovery_ctx ctx;
+
+	ctx.pos = log->last_checkpoint;
+	ctx.seq = log->last_cp_seq;
+	ctx.meta_page = alloc_page(GFP_KERNEL);
+	if (!ctx.meta_page)
+		return -ENOMEM;
+
+	r5l_recovery_flush_log(log, &ctx);
+	__free_page(ctx.meta_page);
+
+	/*
+	 * 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
+	 */
+	if (ctx.seq > log->last_cp_seq + 1) {
+		int ret;
+
+		ret = r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq + 10);
+		if (ret)
+			return ret;
+		log->seq = ctx.seq + 11;
+		log->log_start = r5l_ring_add(log, ctx.pos, BLOCK_SECTORS);
+		r5l_write_super(log, ctx.pos);
+	} else {
+		log->log_start = ctx.pos;
+		log->seq = ctx.seq;
+	}
+	return 0;
+}
+
+static void r5l_write_super(struct r5l_log *log, sector_t cp)
+{
+	struct mddev *mddev = log->rdev->mddev;
+
+	log->rdev->journal_tail = cp;
+	set_bit(MD_CHANGE_DEVS, &mddev->flags);
+}
+
+static int r5l_load_log(struct r5l_log *log)
+{
+	struct md_rdev *rdev = log->rdev;
+	struct page *page;
+	struct r5l_meta_block *mb;
+	sector_t cp = log->rdev->journal_tail;
+	u32 stored_crc, expected_crc;
+	bool create_super = false;
+	int ret;
+
+	/* Make sure it's valid */
+	if (cp >= rdev->sectors || round_down(cp, BLOCK_SECTORS) != cp)
+		cp = 0;
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	if (!sync_page_io(rdev, cp, PAGE_SIZE, page, READ, false)) {
+		ret = -EIO;
+		goto ioerr;
+	}
+	mb = page_address(page);
+
+	if (le32_to_cpu(mb->magic) != R5LOG_MAGIC ||
+	    mb->version != R5LOG_VERSION) {
+		create_super = true;
+		goto create;
+	}
+	stored_crc = le32_to_cpu(mb->checksum);
+	mb->checksum = 0;
+	expected_crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
+	if (stored_crc != expected_crc) {
+		create_super = true;
+		goto create;
+	}
+	if (le64_to_cpu(mb->position) != cp) {
+		create_super = true;
+		goto create;
+	}
+create:
+	if (create_super) {
+		log->last_cp_seq = prandom_u32();
+		cp = 0;
+		/*
+		 * Make sure super points to correct address. Log might have
+		 * data very soon. If super hasn't correct log tail address,
+		 * recovery can't find the log
+		 */
+		r5l_write_super(log, cp);
+	} else
+		log->last_cp_seq = le64_to_cpu(mb->seq);
+
+	log->device_size = round_down(rdev->sectors, BLOCK_SECTORS);
+	log->max_free_space = log->device_size >> RECLAIM_MAX_FREE_SPACE_SHIFT;
+	if (log->max_free_space > RECLAIM_MAX_FREE_SPACE)
+		log->max_free_space = RECLAIM_MAX_FREE_SPACE;
+	log->last_checkpoint = cp;
+
+	__free_page(page);
+
+	return r5l_recovery_log(log);
+ioerr:
+	__free_page(page);
+	return ret;
+}
+
+int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
+{
+	struct r5l_log *log;
+
+	if (PAGE_SIZE != 4096)
+		return -EINVAL;
+	log = kzalloc(sizeof(*log), GFP_KERNEL);
+	if (!log)
+		return -ENOMEM;
+	log->rdev = rdev;
+
+	log->need_cache_flush = (rdev->bdev->bd_disk->queue->flush_flags != 0);
+
+	log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
+				       sizeof(rdev->mddev->uuid));
+
+	mutex_init(&log->io_mutex);
+
+	spin_lock_init(&log->io_list_lock);
+	INIT_LIST_HEAD(&log->running_ios);
+	INIT_LIST_HEAD(&log->io_end_ios);
+	INIT_LIST_HEAD(&log->flushing_ios);
+	INIT_LIST_HEAD(&log->finished_ios);
+	bio_init(&log->flush_bio);
+
+	log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
+	if (!log->io_kc)
+		goto io_kc;
+
+	log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
+						 log->rdev->mddev, "reclaim");
+	if (!log->reclaim_thread)
+		goto reclaim_thread;
+	init_waitqueue_head(&log->iounit_wait);
+
+	INIT_LIST_HEAD(&log->no_space_stripes);
+	spin_lock_init(&log->no_space_stripes_lock);
+
+	if (r5l_load_log(log))
+		goto error;
+
+	conf->log = log;
+	return 0;
+error:
+	md_unregister_thread(&log->reclaim_thread);
+reclaim_thread:
+	kmem_cache_destroy(log->io_kc);
+io_kc:
+	kfree(log);
+	return -EINVAL;
+}
+
+void r5l_exit_log(struct r5l_log *log)
+{
+	md_unregister_thread(&log->reclaim_thread);
+	kmem_cache_destroy(log->io_kc);
+	kfree(log);
+}