raid5-cache.c 68.3 KB
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/*
 * Copyright (C) 2015 Shaohua Li <shli@fb.com>
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 * Copyright (C) 2016 Song Liu <songliubraving@fb.com>
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 *
 * 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>
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#include <linux/crc32c.h>
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#include <linux/random.h>
#include "md.h"
#include "raid5.h"
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#include "bitmap.h"
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/*
 * 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)

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/*
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 * log->max_free_space is min(1/4 disk size, 10G reclaimable space).
 *
 * In write through mode, the reclaim runs every log->max_free_space.
 * This can prevent the recovery scans for too long
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 */
#define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
#define RECLAIM_MAX_FREE_SPACE_SHIFT (2)

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/* wake up reclaim thread periodically */
#define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ)
/* start flush with these full stripes */
#define R5C_FULL_STRIPE_FLUSH_BATCH 256
/* reclaim stripes in groups */
#define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2)

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/*
 * We only need 2 bios per I/O unit to make progress, but ensure we
 * have a few more available to not get too tight.
 */
#define R5L_POOL_SIZE	4

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/*
 * r5c journal modes of the array: write-back or write-through.
 * write-through mode has identical behavior as existing log only
 * implementation.
 */
enum r5c_journal_mode {
	R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
	R5C_JOURNAL_MODE_WRITE_BACK = 1,
};

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static char *r5c_journal_mode_str[] = {"write-through",
				       "write-back"};
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/*
 * raid5 cache state machine
 *
 * With rhe RAID cache, each stripe works in two phases:
 *	- caching phase
 *	- writing-out phase
 *
 * These two phases are controlled by bit STRIPE_R5C_CACHING:
 *   if STRIPE_R5C_CACHING == 0, the stripe is in writing-out phase
 *   if STRIPE_R5C_CACHING == 1, the stripe is in caching phase
 *
 * When there is no journal, or the journal is in write-through mode,
 * the stripe is always in writing-out phase.
 *
 * For write-back journal, the stripe is sent to caching phase on write
 * (r5c_try_caching_write). r5c_make_stripe_write_out() kicks off
 * the write-out phase by clearing STRIPE_R5C_CACHING.
 *
 * Stripes in caching phase do not write the raid disks. Instead, all
 * writes are committed from the log device. Therefore, a stripe in
 * caching phase handles writes as:
 *	- write to log device
 *	- return IO
 *
 * Stripes in writing-out phase handle writes as:
 *	- calculate parity
 *	- write pending data and parity to journal
 *	- write data and parity to raid disks
 *	- return IO for pending writes
 */

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struct r5l_log {
	struct md_rdev *rdev;

	u32 uuid_checksum;

	sector_t device_size;		/* log device size, round to
					 * BLOCK_SECTORS */
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	sector_t max_free_space;	/* reclaim run if free space is at
					 * this size */
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	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 */

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	sector_t next_checkpoint;
	u64 next_cp_seq;

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	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 */
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	struct list_head flushing_ios;	/* io_units which are waiting for log
					 * cache flush */
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	struct list_head finished_ios;	/* io_units which settle down in log disk */
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	struct bio flush_bio;
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	struct list_head no_mem_stripes;   /* pending stripes, -ENOMEM */

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	struct kmem_cache *io_kc;
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	mempool_t *io_pool;
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	struct bio_set *bs;
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	mempool_t *meta_pool;
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	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) */
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	wait_queue_head_t iounit_wait;
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	struct list_head no_space_stripes; /* pending stripes, log has no space */
	spinlock_t no_space_stripes_lock;
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	bool need_cache_flush;
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	/* for r5c_cache */
	enum r5c_journal_mode r5c_journal_mode;
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	/* all stripes in r5cache, in the order of seq at sh->log_start */
	struct list_head stripe_in_journal_list;

	spinlock_t stripe_in_journal_lock;
	atomic_t stripe_in_journal_count;
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};

/*
 * 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;
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	bool need_split_bio;
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};

/* 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 */
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	IO_UNIT_STRIPE_END = 3,	/* stripes data finished writing to raid */
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};

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bool r5c_is_writeback(struct r5l_log *log)
{
	return (log != NULL &&
		log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK);
}

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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_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;
}

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static void
r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev,
			      struct bio_list *return_bi)
{
	struct bio *wbi, *wbi2;

	wbi = dev->written;
	dev->written = NULL;
	while (wbi && wbi->bi_iter.bi_sector <
	       dev->sector + STRIPE_SECTORS) {
		wbi2 = r5_next_bio(wbi, dev->sector);
		if (!raid5_dec_bi_active_stripes(wbi)) {
			md_write_end(conf->mddev);
			bio_list_add(return_bi, wbi);
		}
		wbi = wbi2;
	}
}

void r5c_handle_cached_data_endio(struct r5conf *conf,
	  struct stripe_head *sh, int disks, struct bio_list *return_bi)
{
	int i;

	for (i = sh->disks; i--; ) {
		if (sh->dev[i].written) {
			set_bit(R5_UPTODATE, &sh->dev[i].flags);
			r5c_return_dev_pending_writes(conf, &sh->dev[i],
						      return_bi);
			bitmap_endwrite(conf->mddev->bitmap, sh->sector,
					STRIPE_SECTORS,
					!test_bit(STRIPE_DEGRADED, &sh->state),
					0);
		}
	}
}

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/* Check whether we should flush some stripes to free up stripe cache */
void r5c_check_stripe_cache_usage(struct r5conf *conf)
{
	int total_cached;

	if (!r5c_is_writeback(conf->log))
		return;

	total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
		atomic_read(&conf->r5c_cached_full_stripes);

	/*
	 * The following condition is true for either of the following:
	 *   - stripe cache pressure high:
	 *          total_cached > 3/4 min_nr_stripes ||
	 *          empty_inactive_list_nr > 0
	 *   - stripe cache pressure moderate:
	 *          total_cached > 1/2 min_nr_stripes
	 */
	if (total_cached > conf->min_nr_stripes * 1 / 2 ||
	    atomic_read(&conf->empty_inactive_list_nr) > 0)
		r5l_wake_reclaim(conf->log, 0);
}

/*
 * flush cache when there are R5C_FULL_STRIPE_FLUSH_BATCH or more full
 * stripes in the cache
 */
void r5c_check_cached_full_stripe(struct r5conf *conf)
{
	if (!r5c_is_writeback(conf->log))
		return;

	/*
	 * wake up reclaim for R5C_FULL_STRIPE_FLUSH_BATCH cached stripes
	 * or a full stripe (chunk size / 4k stripes).
	 */
	if (atomic_read(&conf->r5c_cached_full_stripes) >=
	    min(R5C_FULL_STRIPE_FLUSH_BATCH,
		conf->chunk_sectors >> STRIPE_SHIFT))
		r5l_wake_reclaim(conf->log, 0);
}

/*
 * Total log space (in sectors) needed to flush all data in cache
 *
 * Currently, writing-out phase automatically includes all pending writes
 * to the same sector. So the reclaim of each stripe takes up to
 * (conf->raid_disks + 1) pages of log space.
 *
 * To totally avoid deadlock due to log space, the code reserves
 * (conf->raid_disks + 1) pages for each stripe in cache, which is not
 * necessary in most cases.
 *
 * To improve this, we will need writing-out phase to be able to NOT include
 * pending writes, which will reduce the requirement to
 * (conf->max_degraded + 1) pages per stripe in cache.
 */
static sector_t r5c_log_required_to_flush_cache(struct r5conf *conf)
{
	struct r5l_log *log = conf->log;

	if (!r5c_is_writeback(log))
		return 0;

	return BLOCK_SECTORS * (conf->raid_disks + 1) *
		atomic_read(&log->stripe_in_journal_count);
}

/*
 * evaluate log space usage and update R5C_LOG_TIGHT and R5C_LOG_CRITICAL
 *
 * R5C_LOG_TIGHT is set when free space on the log device is less than 3x of
 * reclaim_required_space. R5C_LOG_CRITICAL is set when free space on the log
 * device is less than 2x of reclaim_required_space.
 */
static inline void r5c_update_log_state(struct r5l_log *log)
{
	struct r5conf *conf = log->rdev->mddev->private;
	sector_t free_space;
	sector_t reclaim_space;

	if (!r5c_is_writeback(log))
		return;

	free_space = r5l_ring_distance(log, log->log_start,
				       log->last_checkpoint);
	reclaim_space = r5c_log_required_to_flush_cache(conf);
	if (free_space < 2 * reclaim_space)
		set_bit(R5C_LOG_CRITICAL, &conf->cache_state);
	else
		clear_bit(R5C_LOG_CRITICAL, &conf->cache_state);
	if (free_space < 3 * reclaim_space)
		set_bit(R5C_LOG_TIGHT, &conf->cache_state);
	else
		clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
}

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/*
 * Put the stripe into writing-out phase by clearing STRIPE_R5C_CACHING.
 * This function should only be called in write-back mode.
 */
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void r5c_make_stripe_write_out(struct stripe_head *sh)
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{
	struct r5conf *conf = sh->raid_conf;
	struct r5l_log *log = conf->log;

	BUG_ON(!r5c_is_writeback(log));

	WARN_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
	clear_bit(STRIPE_R5C_CACHING, &sh->state);
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	if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
		atomic_inc(&conf->preread_active_stripes);

	if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) {
		BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0);
		atomic_dec(&conf->r5c_cached_partial_stripes);
	}

	if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
		BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0);
		atomic_dec(&conf->r5c_cached_full_stripes);
	}
}

static void r5c_handle_data_cached(struct stripe_head *sh)
{
	int i;

	for (i = sh->disks; i--; )
		if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
			set_bit(R5_InJournal, &sh->dev[i].flags);
			clear_bit(R5_LOCKED, &sh->dev[i].flags);
		}
	clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
}

/*
 * this journal write must contain full parity,
 * it may also contain some data pages
 */
static void r5c_handle_parity_cached(struct stripe_head *sh)
{
	int i;

	for (i = sh->disks; i--; )
		if (test_bit(R5_InJournal, &sh->dev[i].flags))
			set_bit(R5_Wantwrite, &sh->dev[i].flags);
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}

/*
 * Setting proper flags after writing (or flushing) data and/or parity to the
 * log device. This is called from r5l_log_endio() or r5l_log_flush_endio().
 */
static void r5c_finish_cache_stripe(struct stripe_head *sh)
{
	struct r5l_log *log = sh->raid_conf->log;

	if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
		BUG_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
		/*
		 * Set R5_InJournal for parity dev[pd_idx]. This means
		 * all data AND parity in the journal. For RAID 6, it is
		 * NOT necessary to set the flag for dev[qd_idx], as the
		 * two parities are written out together.
		 */
		set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
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	} else if (test_bit(STRIPE_R5C_CACHING, &sh->state)) {
		r5c_handle_data_cached(sh);
	} else {
		r5c_handle_parity_cached(sh);
		set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
	}
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}

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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);
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		r5c_finish_cache_stripe(sh);

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		set_bit(STRIPE_HANDLE, &sh->state);
		raid5_release_stripe(sh);
	}
}

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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);
	}
}

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static void r5l_move_to_end_ios(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->io_end_ios);
	}
}

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static void r5l_log_endio(struct bio *bio)
{
	struct r5l_io_unit *io = bio->bi_private;
	struct r5l_log *log = io->log;
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	unsigned long flags;
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	if (bio->bi_error)
		md_error(log->rdev->mddev, log->rdev);

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	bio_put(bio);
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	mempool_free(io->meta_page, log->meta_pool);
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	spin_lock_irqsave(&log->io_list_lock, flags);
	__r5l_set_io_unit_state(io, IO_UNIT_IO_END);
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	if (log->need_cache_flush)
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		r5l_move_to_end_ios(log);
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	else
		r5l_log_run_stripes(log);
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	spin_unlock_irqrestore(&log->io_list_lock, flags);

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	if (log->need_cache_flush)
		md_wakeup_thread(log->rdev->mddev->thread);
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}

static void r5l_submit_current_io(struct r5l_log *log)
{
	struct r5l_io_unit *io = log->current_io;
	struct r5l_meta_block *block;
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	unsigned long flags;
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	u32 crc;

	if (!io)
		return;

	block = page_address(io->meta_page);
	block->meta_size = cpu_to_le32(io->meta_offset);
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	crc = crc32c_le(log->uuid_checksum, block, PAGE_SIZE);
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	block->checksum = cpu_to_le32(crc);

	log->current_io = NULL;
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	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);
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	submit_bio(io->current_bio);
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}

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static struct bio *r5l_bio_alloc(struct r5l_log *log)
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{
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	struct bio *bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, log->bs);
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	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
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	bio->bi_bdev = log->rdev->bdev;
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	bio->bi_iter.bi_sector = log->rdev->data_offset + log->log_start;
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	return bio;
}

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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);

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	r5c_update_log_state(log);
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	/*
	 * 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)
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		io->need_split_bio = true;
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	io->log_end = log->log_start;
}

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static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
{
	struct r5l_io_unit *io;
	struct r5l_meta_block *block;

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	io = mempool_alloc(log->io_pool, GFP_ATOMIC);
	if (!io)
		return NULL;
	memset(io, 0, sizeof(*io));

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	io->log = log;
	INIT_LIST_HEAD(&io->log_sibling);
	INIT_LIST_HEAD(&io->stripe_list);
	io->state = IO_UNIT_RUNNING;
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588
	io->meta_page = mempool_alloc(log->meta_pool, GFP_NOIO);
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	block = page_address(io->meta_page);
590
	clear_page(block);
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	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);
598
	io->seq = log->seq++;
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	io->current_bio = r5l_bio_alloc(log);
	io->current_bio->bi_end_io = r5l_log_endio;
	io->current_bio->bi_private = io;
603
	bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
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605
	r5_reserve_log_entry(log, io);
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	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)
{
616 617
	if (log->current_io &&
	    log->current_io->meta_offset + payload_size > PAGE_SIZE)
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		r5l_submit_current_io(log);

620
	if (!log->current_io) {
621
		log->current_io = r5l_new_meta(log);
622 623 624 625
		if (!log->current_io)
			return -ENOMEM;
	}

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	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;

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	if (io->need_split_bio) {
		struct bio *prev = io->current_bio;
657

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		io->current_bio = r5l_bio_alloc(log);
		bio_chain(io->current_bio, prev);

661
		submit_bio(prev);
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	}

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	if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0))
		BUG();

667
	r5_reserve_log_entry(log, io);
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}

670
static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
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			   int data_pages, int parity_pages)
{
	int i;
	int meta_size;
675
	int ret;
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	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;

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	ret = r5l_get_meta(log, meta_size);
	if (ret)
		return ret;

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	io = log->current_io;

	for (i = 0; i < sh->disks; i++) {
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		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
		    test_bit(R5_InJournal, &sh->dev[i].flags))
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			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);
	}

702
	if (parity_pages == 2) {
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		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);
708
	} else if (parity_pages == 1) {
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		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);
713 714
	} else  /* Just writing data, not parity, in caching phase */
		BUG_ON(parity_pages != 0);
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	list_add_tail(&sh->log_list, &io->stripe_list);
	atomic_inc(&io->pending_stripe);
	sh->log_io = io;
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720 721 722 723 724 725 726 727 728 729 730 731
	if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
		return 0;

	if (sh->log_start == MaxSector) {
		BUG_ON(!list_empty(&sh->r5c));
		sh->log_start = io->log_start;
		spin_lock_irq(&log->stripe_in_journal_lock);
		list_add_tail(&sh->r5c,
			      &log->stripe_in_journal_list);
		spin_unlock_irq(&log->stripe_in_journal_lock);
		atomic_inc(&log->stripe_in_journal_count);
	}
732
	return 0;
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}

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/* add stripe to no_space_stripes, and then wake up reclaim */
static inline void r5l_add_no_space_stripe(struct r5l_log *log,
					   struct stripe_head *sh)
{
	spin_lock(&log->no_space_stripes_lock);
	list_add_tail(&sh->log_list, &log->no_space_stripes);
	spin_unlock(&log->no_space_stripes_lock);
}

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/*
 * 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)
{
750
	struct r5conf *conf = sh->raid_conf;
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	int write_disks = 0;
	int data_pages, parity_pages;
	int reserve;
	int i;
755
	int ret = 0;
756
	bool wake_reclaim = false;
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	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;
	}

768 769
	WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));

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	for (i = 0; i < sh->disks; i++) {
		void *addr;

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		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags) ||
		    test_bit(R5_InJournal, &sh->dev[i].flags))
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			continue;
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		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);
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		sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
						    addr, PAGE_SIZE);
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		kunmap_atomic(addr);
	}
	parity_pages = 1 + !!(sh->qd_idx >= 0);
	data_pages = write_disks - parity_pages;

	set_bit(STRIPE_LOG_TRAPPED, &sh->state);
790 791 792 793 794
	/*
	 * The stripe must enter state machine again to finish the write, so
	 * don't delay.
	 */
	clear_bit(STRIPE_DELAYED, &sh->state);
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	atomic_inc(&sh->count);

	mutex_lock(&log->io_mutex);
	/* meta + data */
	reserve = (1 + write_disks) << (PAGE_SHIFT - 9);

801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836
	if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
		if (!r5l_has_free_space(log, reserve)) {
			r5l_add_no_space_stripe(log, sh);
			wake_reclaim = true;
		} else {
			ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
			if (ret) {
				spin_lock_irq(&log->io_list_lock);
				list_add_tail(&sh->log_list,
					      &log->no_mem_stripes);
				spin_unlock_irq(&log->io_list_lock);
			}
		}
	} else {  /* R5C_JOURNAL_MODE_WRITE_BACK */
		/*
		 * log space critical, do not process stripes that are
		 * not in cache yet (sh->log_start == MaxSector).
		 */
		if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
		    sh->log_start == MaxSector) {
			r5l_add_no_space_stripe(log, sh);
			wake_reclaim = true;
			reserve = 0;
		} else if (!r5l_has_free_space(log, reserve)) {
			if (sh->log_start == log->last_checkpoint)
				BUG();
			else
				r5l_add_no_space_stripe(log, sh);
		} else {
			ret = r5l_log_stripe(log, sh, data_pages, parity_pages);
			if (ret) {
				spin_lock_irq(&log->io_list_lock);
				list_add_tail(&sh->log_list,
					      &log->no_mem_stripes);
				spin_unlock_irq(&log->io_list_lock);
			}
837
		}
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	}

840
	mutex_unlock(&log->io_mutex);
841 842
	if (wake_reclaim)
		r5l_wake_reclaim(log, reserve);
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	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);
}

855 856 857 858 859 860 861 862 863 864 865 866 867 868
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;
	}
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	bio->bi_opf &= ~REQ_PREFLUSH;
870 871 872
	return -EAGAIN;
}

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/* 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);
}

889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916
/*
 * calculate new last_checkpoint
 * for write through mode, returns log->next_checkpoint
 * for write back, returns log_start of first sh in stripe_in_journal_list
 */
static sector_t r5c_calculate_new_cp(struct r5conf *conf)
{
	struct stripe_head *sh;
	struct r5l_log *log = conf->log;
	sector_t new_cp;
	unsigned long flags;

	if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
		return log->next_checkpoint;

	spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
	if (list_empty(&conf->log->stripe_in_journal_list)) {
		/* all stripes flushed */
		spin_unlock(&log->stripe_in_journal_lock);
		return log->next_checkpoint;
	}
	sh = list_first_entry(&conf->log->stripe_in_journal_list,
			      struct stripe_head, r5c);
	new_cp = sh->log_start;
	spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
	return new_cp;
}

917 918
static sector_t r5l_reclaimable_space(struct r5l_log *log)
{
919 920
	struct r5conf *conf = log->rdev->mddev->private;

921
	return r5l_ring_distance(log, log->last_checkpoint,
922
				 r5c_calculate_new_cp(conf));
923 924
}

925 926 927 928 929 930 931 932 933 934 935 936 937 938 939
static void r5l_run_no_mem_stripe(struct r5l_log *log)
{
	struct stripe_head *sh;

	assert_spin_locked(&log->io_list_lock);

	if (!list_empty(&log->no_mem_stripes)) {
		sh = list_first_entry(&log->no_mem_stripes,
				      struct stripe_head, log_list);
		list_del_init(&sh->log_list);
		set_bit(STRIPE_HANDLE, &sh->state);
		raid5_release_stripe(sh);
	}
}

940
static bool r5l_complete_finished_ios(struct r5l_log *log)
941 942 943 944 945 946
{
	struct r5l_io_unit *io, *next;
	bool found = false;

	assert_spin_locked(&log->io_list_lock);

947
	list_for_each_entry_safe(io, next, &log->finished_ios, log_sibling) {
948 949 950 951 952 953 954 955
		/* 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);
956 957
		mempool_free(io, log->io_pool);
		r5l_run_no_mem_stripe(log);
958 959 960 961 962 963 964

		found = true;
	}

	return found;
}

965 966 967
static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
{
	struct r5l_log *log = io->log;
968
	struct r5conf *conf = log->rdev->mddev->private;
969 970 971 972
	unsigned long flags;

	spin_lock_irqsave(&log->io_list_lock, flags);
	__r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
973

974
	if (!r5l_complete_finished_ios(log)) {
975 976 977
		spin_unlock_irqrestore(&log->io_list_lock, flags);
		return;
	}
978

979 980
	if (r5l_reclaimable_space(log) > log->max_free_space ||
	    test_bit(R5C_LOG_TIGHT, &conf->cache_state))
981 982 983 984 985 986
		r5l_wake_reclaim(log, 0);

	spin_unlock_irqrestore(&log->io_list_lock, flags);
	wake_up(&log->iounit_wait);
}

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void r5l_stripe_write_finished(struct stripe_head *sh)
{
	struct r5l_io_unit *io;

	io = sh->log_io;
	sh->log_io = NULL;

994 995
	if (io && atomic_dec_and_test(&io->pending_stripe))
		__r5l_stripe_write_finished(io);
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}

998 999 1000 1001 1002 1003 1004
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;

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	if (bio->bi_error)
		md_error(log->rdev->mddev, log->rdev);

1008
	spin_lock_irqsave(&log->io_list_lock, flags);
1009 1010
	list_for_each_entry(io, &log->flushing_ios, log_sibling)
		r5l_io_run_stripes(io);
1011
	list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
1012 1013 1014
	spin_unlock_irqrestore(&log->io_list_lock, flags);
}

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/*
 * 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)
{
1031
	bool do_flush;
1032 1033

	if (!log || !log->need_cache_flush)
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		return;

	spin_lock_irq(&log->io_list_lock);
1037 1038 1039 1040
	/* flush bio is running */
	if (!list_empty(&log->flushing_ios)) {
		spin_unlock_irq(&log->io_list_lock);
		return;
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	}
1042 1043
	list_splice_tail_init(&log->io_end_ios, &log->flushing_ios);
	do_flush = !list_empty(&log->flushing_ios);
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	spin_unlock_irq(&log->io_list_lock);
1045 1046 1047 1048 1049 1050

	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;
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	bio_set_op_attrs(&log->flush_bio, REQ_OP_WRITE, WRITE_FLUSH);
1052
	submit_bio(&log->flush_bio);
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}

static void r5l_write_super(struct r5l_log *log, sector_t cp);
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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;
	/*
1069 1070 1071 1072 1073 1074 1075 1076 1077
	 * Discard could zero data, so before discard we must make sure
	 * superblock is updated to new log tail. Updating superblock (either
	 * directly call md_update_sb() or depend on md thread) must hold
	 * reconfig mutex. On the other hand, raid5_quiesce is called with
	 * reconfig_mutex hold. The first step of raid5_quiesce() is waitting
	 * for all IO finish, hence waitting for reclaim thread, while reclaim
	 * thread is calling this function and waitting for reconfig mutex. So
	 * there is a deadlock. We workaround this issue with a trylock.
	 * FIXME: we could miss discard if we can't take reconfig mutex
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	 */
1079 1080 1081 1082 1083 1084
	set_mask_bits(&mddev->flags, 0,
		BIT(MD_CHANGE_DEVS) | BIT(MD_CHANGE_PENDING));
	if (!mddev_trylock(mddev))
		return;
	md_update_sb(mddev, 1);
	mddev_unlock(mddev);
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	/* discard IO error really doesn't matter, ignore it */
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	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);
	}
}

1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
/*
 * r5c_flush_stripe moves stripe from cached list to handle_list. When called,
 * the stripe must be on r5c_cached_full_stripes or r5c_cached_partial_stripes.
 *
 * must hold conf->device_lock
 */
static void r5c_flush_stripe(struct r5conf *conf, struct stripe_head *sh)
{
	BUG_ON(list_empty(&sh->lru));
	BUG_ON(!test_bit(STRIPE_R5C_CACHING, &sh->state));
	BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));

	/*
	 * The stripe is not ON_RELEASE_LIST, so it is safe to call
	 * raid5_release_stripe() while holding conf->device_lock
	 */
	BUG_ON(test_bit(STRIPE_ON_RELEASE_LIST, &sh->state));
	assert_spin_locked(&conf->device_lock);

	list_del_init(&sh->lru);
	atomic_inc(&sh->count);

	set_bit(STRIPE_HANDLE, &sh->state);
	atomic_inc(&conf->active_stripes);
	r5c_make_stripe_write_out(sh);

	if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
		atomic_inc(&conf->preread_active_stripes);
	raid5_release_stripe(sh);
}

/*
 * if num == 0, flush all full stripes
 * if num > 0, flush all full stripes. If less than num full stripes are
 *             flushed, flush some partial stripes until totally num stripes are
 *             flushed or there is no more cached stripes.
 */
void r5c_flush_cache(struct r5conf *conf, int num)
{
	int count;
	struct stripe_head *sh, *next;

	assert_spin_locked(&conf->device_lock);
	if (!conf->log)
		return;

	count = 0;
	list_for_each_entry_safe(sh, next, &conf->r5c_full_stripe_list, lru) {
		r5c_flush_stripe(conf, sh);
		count++;
	}

	if (count >= num)
		return;
	list_for_each_entry_safe(sh, next,
				 &conf->r5c_partial_stripe_list, lru) {
		r5c_flush_stripe(conf, sh);
		if (++count >= num)
			break;
	}
}

static void r5c_do_reclaim(struct r5conf *conf)
{
	struct r5l_log *log = conf->log;
	struct stripe_head *sh;
	int count = 0;
	unsigned long flags;
	int total_cached;
	int stripes_to_flush;

	if (!r5c_is_writeback(log))
		return;

	total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
		atomic_read(&conf->r5c_cached_full_stripes);

	if (total_cached > conf->min_nr_stripes * 3 / 4 ||
	    atomic_read(&conf->empty_inactive_list_nr) > 0)
		/*
		 * if stripe cache pressure high, flush all full stripes and
		 * some partial stripes
		 */
		stripes_to_flush = R5C_RECLAIM_STRIPE_GROUP;
	else if (total_cached > conf->min_nr_stripes * 1 / 2 ||
		 atomic_read(&conf->r5c_cached_full_stripes) >
		 R5C_FULL_STRIPE_FLUSH_BATCH)
		/*
		 * if stripe cache pressure moderate, or if there is many full
		 * stripes,flush all full stripes
		 */
		stripes_to_flush = 0;
	else
		/* no need to flush */
		stripes_to_flush = -1;

	if (stripes_to_flush >= 0) {
		spin_lock_irqsave(&conf->device_lock, flags);
		r5c_flush_cache(conf, stripes_to_flush);
		spin_unlock_irqrestore(&conf->device_lock, flags);
	}

	/* if log space is tight, flush stripes on stripe_in_journal_list */
	if (test_bit(R5C_LOG_TIGHT, &conf->cache_state)) {
		spin_lock_irqsave(&log->stripe_in_journal_lock, flags);
		spin_lock(&conf->device_lock);
		list_for_each_entry(sh, &log->stripe_in_journal_list, r5c) {
			/*
			 * stripes on stripe_in_journal_list could be in any
			 * state of the stripe_cache state machine. In this
			 * case, we only want to flush stripe on
			 * r5c_cached_full/partial_stripes. The following
			 * condition makes sure the stripe is on one of the
			 * two lists.
			 */
			if (!list_empty(&sh->lru) &&
			    !test_bit(STRIPE_HANDLE, &sh->state) &&
			    atomic_read(&sh->count) == 0) {
				r5c_flush_stripe(conf, sh);
			}
			if (count++ >= R5C_RECLAIM_STRIPE_GROUP)
				break;
		}
		spin_unlock(&conf->device_lock);
		spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
	}
	md_wakeup_thread(conf->mddev->thread);
}

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static void r5l_do_reclaim(struct r5l_log *log)
{
1232
	struct r5conf *conf = log->rdev->mddev->private;
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	sector_t reclaim_target = xchg(&log->reclaim_target, 0);
1234 1235
	sector_t reclaimable;
	sector_t next_checkpoint;
1236
	bool write_super;
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	spin_lock_irq(&log->io_list_lock);
1239 1240
	write_super = r5l_reclaimable_space(log) > log->max_free_space ||
		reclaim_target != 0 || !list_empty(&log->no_space_stripes);
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	/*
	 * 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) {
1247 1248
		reclaimable = r5l_reclaimable_space(log);
		if (reclaimable >= reclaim_target ||
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		    (list_empty(&log->running_ios) &&
		     list_empty(&log->io_end_ios) &&
1251
		     list_empty(&log->flushing_ios) &&
1252
		     list_empty(&log->finished_ios)))
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			break;

1255 1256 1257 1258
		md_wakeup_thread(log->rdev->mddev->thread);
		wait_event_lock_irq(log->iounit_wait,
				    r5l_reclaimable_space(log) > reclaimable,
				    log->io_list_lock);
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	}
1260

1261
	next_checkpoint = r5c_calculate_new_cp(conf);
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	spin_unlock_irq(&log->io_list_lock);

1264
	BUG_ON(reclaimable < 0);
1265 1266

	if (reclaimable == 0 || !write_super)
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		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
	 */
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	r5l_write_super_and_discard_space(log, next_checkpoint);
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	mutex_lock(&log->io_mutex);
1277
	log->last_checkpoint = next_checkpoint;
1278
	r5c_update_log_state(log);
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	mutex_unlock(&log->io_mutex);

1281
	r5l_run_no_space_stripes(log);
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}

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;
1292
	r5c_do_reclaim(conf);
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	r5l_do_reclaim(log);
}

1296
void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
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{
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	unsigned long target;
	unsigned long new = (unsigned long)space; /* overflow in theory */

1301 1302
	if (!log)
		return;
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	do {
		target = log->reclaim_target;
		if (new < target)
			return;
	} while (cmpxchg(&log->reclaim_target, target, new) != target);
	md_wakeup_thread(log->reclaim_thread);
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}

1311 1312
void r5l_quiesce(struct r5l_log *log, int state)
{
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	struct mddev *mddev;
1314 1315 1316
	if (!log || state == 2)
		return;
	if (state == 0) {
1317 1318 1319 1320 1321 1322 1323
		/*
		 * This is a special case for hotadd. In suspend, the array has
		 * no journal. In resume, journal is initialized as well as the
		 * reclaim thread.
		 */
		if (log->reclaim_thread)
			return;
1324 1325
		log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
					log->rdev->mddev, "reclaim");
1326
		log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
1327
	} else if (state == 1) {
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		/* make sure r5l_write_super_and_discard_space exits */
		mddev = log->rdev->mddev;
		wake_up(&mddev->sb_wait);
1331
		r5l_wake_reclaim(log, MaxSector);
1332 1333 1334 1335 1336
		md_unregister_thread(&log->reclaim_thread);
		r5l_do_reclaim(log);
	}
}

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bool r5l_log_disk_error(struct r5conf *conf)
{
1339 1340
	struct r5l_log *log;
	bool ret;
1341
	/* don't allow write if journal disk is missing */
1342 1343 1344 1345 1346 1347 1348 1349 1350
	rcu_read_lock();
	log = rcu_dereference(conf->log);

	if (!log)
		ret = test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
	else
		ret = test_bit(Faulty, &log->rdev->flags);
	rcu_read_unlock();
	return ret;
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}

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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 */
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	int data_parity_stripes;	/* number of data_parity stripes */
	int data_only_stripes;		/* number of data_only stripes */
	struct list_head cached_list;
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};

1363 1364
static int r5l_recovery_read_meta_block(struct r5l_log *log,
					struct r5l_recovery_ctx *ctx)
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{
	struct page *page = ctx->meta_page;
	struct r5l_meta_block *mb;
	u32 crc, stored_crc;

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	if (!sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page, REQ_OP_READ, 0,
			  false))
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		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;

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	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
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	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;
}

1396 1397 1398 1399
static void
r5l_recovery_create_empty_meta_block(struct r5l_log *log,
				     struct page *page,
				     sector_t pos, u64 seq)
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{
	struct r5l_meta_block *mb;
	u32 crc;

	mb = page_address(page);
1405
	clear_page(mb);
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	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);
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	crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
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	mb->checksum = cpu_to_le32(crc);
1413
}
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1415 1416 1417 1418 1419 1420 1421 1422 1423
static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
					  u64 seq)
{
	struct page *page;

	page = alloc_page(GFP_KERNEL);
	if (!page)
		return -ENOMEM;
	r5l_recovery_create_empty_meta_block(log, page, pos, seq);
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	if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,
			  WRITE_FUA, false)) {
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		__free_page(page);
		return -EIO;
	}
	__free_page(page);
	return 0;
}

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/*
 * 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;
}

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static int r5l_recovery_log(struct r5l_log *log)
{
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	struct mddev *mddev = log->rdev->mddev;
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	struct r5l_recovery_ctx ctx;
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	int ret;
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	ctx.pos = log->last_checkpoint;
	ctx.seq = log->last_cp_seq;
	ctx.meta_page = alloc_page(GFP_KERNEL);
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	ctx.data_only_stripes = 0;
	ctx.data_parity_stripes = 0;
	INIT_LIST_HEAD(&ctx.cached_list);

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	if (!ctx.meta_page)
		return -ENOMEM;

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	ret = r5c_recovery_flush_log(log, &ctx);
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	__free_page(ctx.meta_page);

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	if (ret)
		return ret;
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	if ((ctx.data_only_stripes == 0) && (ctx.data_parity_stripes == 0))
		pr_debug("md/raid:%s: starting from clean shutdown\n",
			 mdname(mddev));
	else {
		pr_debug("md/raid:%s: recoverying %d data-only stripes and %d data-parity stripes\n",
			 mdname(mddev), ctx.data_only_stripes,
			 ctx.data_parity_stripes);

		if (ctx.data_only_stripes > 0)
			if (r5c_recovery_rewrite_data_only_stripes(log, &ctx)) {
				pr_err("md/raid:%s: failed to rewrite stripes to journal\n",
				       mdname(mddev));
				return -EIO;
			}
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	}

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	log->log_start = ctx.pos;
	log->next_checkpoint = ctx.pos;
	log->seq = ctx.seq;
	r5l_log_write_empty_meta_block(log, ctx.pos, ctx.seq);
	r5l_write_super(log, ctx.pos);
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	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);
}

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static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
{
	struct r5conf *conf = mddev->private;
	int ret;

	if (!conf->log)
		return 0;

	switch (conf->log->r5c_journal_mode) {
	case R5C_JOURNAL_MODE_WRITE_THROUGH:
		ret = snprintf(
			page, PAGE_SIZE, "[%s] %s\n",
			r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_THROUGH],
			r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_BACK]);
		break;
	case R5C_JOURNAL_MODE_WRITE_BACK:
		ret = snprintf(
			page, PAGE_SIZE, "%s [%s]\n",
			r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_THROUGH],
			r5c_journal_mode_str[R5C_JOURNAL_MODE_WRITE_BACK]);
		break;
	default:
		ret = 0;
	}
	return ret;
}

static ssize_t r5c_journal_mode_store(struct mddev *mddev,
				      const char *page, size_t length)
{
	struct r5conf *conf = mddev->private;
	struct r5l_log *log = conf->log;
	int val = -1, i;
	int len = length;

	if (!log)
		return -ENODEV;

	if (len && page[len - 1] == '\n')
		len -= 1;
	for (i = 0; i < ARRAY_SIZE(r5c_journal_mode_str); i++)
		if (strlen(r5c_journal_mode_str[i]) == len &&
		    strncmp(page, r5c_journal_mode_str[i], len) == 0) {
			val = i;
			break;
		}
	if (val < R5C_JOURNAL_MODE_WRITE_THROUGH ||
	    val > R5C_JOURNAL_MODE_WRITE_BACK)
		return -EINVAL;

	mddev_suspend(mddev);
	conf->log->r5c_journal_mode = val;
	mddev_resume(mddev);

	pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n",
		 mdname(mddev), val, r5c_journal_mode_str[val]);
	return length;
}

struct md_sysfs_entry
r5c_journal_mode = __ATTR(journal_mode, 0644,
			  r5c_journal_mode_show, r5c_journal_mode_store);

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/*
 * Try handle write operation in caching phase. This function should only
 * be called in write-back mode.
 *
 * If all outstanding writes can be handled in caching phase, returns 0
 * If writes requires write-out phase, call r5c_make_stripe_write_out()
 * and returns -EAGAIN
 */
int r5c_try_caching_write(struct r5conf *conf,
			  struct stripe_head *sh,
			  struct stripe_head_state *s,
			  int disks)
{
	struct r5l_log *log = conf->log;
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	int i;
	struct r5dev *dev;
	int to_cache = 0;
2151 2152 2153

	BUG_ON(!r5c_is_writeback(log));

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	if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
		/*
		 * There are two different scenarios here:
		 *  1. The stripe has some data cached, and it is sent to
		 *     write-out phase for reclaim
		 *  2. The stripe is clean, and this is the first write
		 *
		 * For 1, return -EAGAIN, so we continue with
		 * handle_stripe_dirtying().
		 *
		 * For 2, set STRIPE_R5C_CACHING and continue with caching
		 * write.
		 */

		/* case 1: anything injournal or anything in written */
		if (s->injournal > 0 || s->written > 0)
			return -EAGAIN;
		/* case 2 */
		set_bit(STRIPE_R5C_CACHING, &sh->state);
	}

	for (i = disks; i--; ) {
		dev = &sh->dev[i];
		/* if non-overwrite, use writing-out phase */
		if (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags) &&
		    !test_bit(R5_InJournal, &dev->flags)) {
			r5c_make_stripe_write_out(sh);
			return -EAGAIN;
		}
	}

	for (i = disks; i--; ) {
		dev = &sh->dev[i];
		if (dev->towrite) {
			set_bit(R5_Wantwrite, &dev->flags);
			set_bit(R5_Wantdrain, &dev->flags);
			set_bit(R5_LOCKED, &dev->flags);
			to_cache++;
		}
	}

	if (to_cache) {
		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
		/*
		 * set STRIPE_LOG_TRAPPED, which triggers r5c_cache_data()
		 * in ops_run_io(). STRIPE_LOG_TRAPPED will be cleared in
		 * r5c_handle_data_cached()
		 */
		set_bit(STRIPE_LOG_TRAPPED, &sh->state);
	}

	return 0;
}

/*
 * free extra pages (orig_page) we allocated for prexor
 */
void r5c_release_extra_page(struct stripe_head *sh)
{
	int i;

	for (i = sh->disks; i--; )
		if (sh->dev[i].page != sh->dev[i].orig_page) {
			struct page *p = sh->dev[i].orig_page;

			sh->dev[i].orig_page = sh->dev[i].page;
			put_page(p);
		}
2222 2223 2224 2225 2226 2227 2228 2229 2230 2231
}

/*
 * clean up the stripe (clear R5_InJournal for dev[pd_idx] etc.) after the
 * stripe is committed to RAID disks.
 */
void r5c_finish_stripe_write_out(struct r5conf *conf,
				 struct stripe_head *sh,
				 struct stripe_head_state *s)
{
S
Song Liu 已提交
2232 2233 2234
	int i;
	int do_wakeup = 0;

2235 2236 2237 2238 2239 2240 2241 2242 2243
	if (!conf->log ||
	    !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags))
		return;

	WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
	clear_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);

	if (conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
		return;
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2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262

	for (i = sh->disks; i--; ) {
		clear_bit(R5_InJournal, &sh->dev[i].flags);
		if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
			do_wakeup = 1;
	}

	/*
	 * analyse_stripe() runs before r5c_finish_stripe_write_out(),
	 * We updated R5_InJournal, so we also update s->injournal.
	 */
	s->injournal = 0;

	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
		if (atomic_dec_and_test(&conf->pending_full_writes))
			md_wakeup_thread(conf->mddev->thread);

	if (do_wakeup)
		wake_up(&conf->wait_for_overlap);
2263 2264 2265 2266 2267 2268 2269 2270 2271

	if (conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
		return;

	spin_lock_irq(&conf->log->stripe_in_journal_lock);
	list_del_init(&sh->r5c);
	spin_unlock_irq(&conf->log->stripe_in_journal_lock);
	sh->log_start = MaxSector;
	atomic_dec(&conf->log->stripe_in_journal_count);
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}

int
r5c_cache_data(struct r5l_log *log, struct stripe_head *sh,
	       struct stripe_head_state *s)
{
2278
	struct r5conf *conf = sh->raid_conf;
S
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2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309
	int pages = 0;
	int reserve;
	int i;
	int ret = 0;

	BUG_ON(!log);

	for (i = 0; i < sh->disks; i++) {
		void *addr;

		if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
			continue;
		addr = kmap_atomic(sh->dev[i].page);
		sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
						    addr, PAGE_SIZE);
		kunmap_atomic(addr);
		pages++;
	}
	WARN_ON(pages == 0);

	/*
	 * The stripe must enter state machine again to call endio, so
	 * don't delay.
	 */
	clear_bit(STRIPE_DELAYED, &sh->state);
	atomic_inc(&sh->count);

	mutex_lock(&log->io_mutex);
	/* meta + data */
	reserve = (1 + pages) << (PAGE_SHIFT - 9);

2310 2311 2312 2313 2314 2315 2316 2317
	if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
	    sh->log_start == MaxSector)
		r5l_add_no_space_stripe(log, sh);
	else if (!r5l_has_free_space(log, reserve)) {
		if (sh->log_start == log->last_checkpoint)
			BUG();
		else
			r5l_add_no_space_stripe(log, sh);
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2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328
	} else {
		ret = r5l_log_stripe(log, sh, pages, 0);
		if (ret) {
			spin_lock_irq(&log->io_list_lock);
			list_add_tail(&sh->log_list, &log->no_mem_stripes);
			spin_unlock_irq(&log->io_list_lock);
		}
	}

	mutex_unlock(&log->io_mutex);
	return 0;
2329 2330
}

S
Shaohua Li 已提交
2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347
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;

M
Mike Christie 已提交
2348
	if (!sync_page_io(rdev, cp, PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
S
Shaohua Li 已提交
2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360
		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;
S
Shaohua Li 已提交
2361
	expected_crc = crc32c_le(log->uuid_checksum, mb, PAGE_SIZE);
S
Shaohua Li 已提交
2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373
	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;
2374
		r5l_log_write_empty_meta_block(log, cp, log->last_cp_seq);
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Shaohua Li 已提交
2375 2376 2377 2378 2379 2380 2381 2382 2383 2384
		/*
		 * 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);
S
Shaohua Li 已提交
2385 2386 2387
	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;
S
Shaohua Li 已提交
2388
	log->last_checkpoint = cp;
2389
	log->next_checkpoint = cp;
2390 2391 2392
	mutex_lock(&log->io_mutex);
	r5c_update_log_state(log);
	mutex_unlock(&log->io_mutex);
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Shaohua Li 已提交
2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403

	__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)
{
J
Jens Axboe 已提交
2404
	struct request_queue *q = bdev_get_queue(rdev->bdev);
S
Shaohua Li 已提交
2405 2406 2407 2408
	struct r5l_log *log;

	if (PAGE_SIZE != 4096)
		return -EINVAL;
2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424

	/*
	 * The PAGE_SIZE must be big enough to hold 1 r5l_meta_block and
	 * raid_disks r5l_payload_data_parity.
	 *
	 * Write journal and cache does not work for very big array
	 * (raid_disks > 203)
	 */
	if (sizeof(struct r5l_meta_block) +
	    ((sizeof(struct r5l_payload_data_parity) + sizeof(__le32)) *
	     conf->raid_disks) > PAGE_SIZE) {
		pr_err("md/raid:%s: write journal/cache doesn't work for array with %d disks\n",
		       mdname(conf->mddev), conf->raid_disks);
		return -EINVAL;
	}

S
Shaohua Li 已提交
2425 2426 2427 2428 2429
	log = kzalloc(sizeof(*log), GFP_KERNEL);
	if (!log)
		return -ENOMEM;
	log->rdev = rdev;

J
Jens Axboe 已提交
2430
	log->need_cache_flush = test_bit(QUEUE_FLAG_WC, &q->queue_flags) != 0;
2431

S
Shaohua Li 已提交
2432 2433
	log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
				       sizeof(rdev->mddev->uuid));
S
Shaohua Li 已提交
2434 2435 2436 2437 2438

	mutex_init(&log->io_mutex);

	spin_lock_init(&log->io_list_lock);
	INIT_LIST_HEAD(&log->running_ios);
S
Shaohua Li 已提交
2439
	INIT_LIST_HEAD(&log->io_end_ios);
2440
	INIT_LIST_HEAD(&log->flushing_ios);
2441
	INIT_LIST_HEAD(&log->finished_ios);
2442
	bio_init(&log->flush_bio);
S
Shaohua Li 已提交
2443 2444 2445 2446 2447

	log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
	if (!log->io_kc)
		goto io_kc;

2448 2449 2450 2451
	log->io_pool = mempool_create_slab_pool(R5L_POOL_SIZE, log->io_kc);
	if (!log->io_pool)
		goto io_pool;

C
Christoph Hellwig 已提交
2452 2453 2454 2455
	log->bs = bioset_create(R5L_POOL_SIZE, 0);
	if (!log->bs)
		goto io_bs;

2456 2457 2458 2459
	log->meta_pool = mempool_create_page_pool(R5L_POOL_SIZE, 0);
	if (!log->meta_pool)
		goto out_mempool;

S
Shaohua Li 已提交
2460 2461 2462 2463
	log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
						 log->rdev->mddev, "reclaim");
	if (!log->reclaim_thread)
		goto reclaim_thread;
2464 2465
	log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;

2466
	init_waitqueue_head(&log->iounit_wait);
S
Shaohua Li 已提交
2467

2468 2469
	INIT_LIST_HEAD(&log->no_mem_stripes);

S
Shaohua Li 已提交
2470 2471 2472
	INIT_LIST_HEAD(&log->no_space_stripes);
	spin_lock_init(&log->no_space_stripes_lock);

2473
	log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
2474 2475 2476
	INIT_LIST_HEAD(&log->stripe_in_journal_list);
	spin_lock_init(&log->stripe_in_journal_lock);
	atomic_set(&log->stripe_in_journal_count, 0);
2477

S
Shaohua Li 已提交
2478 2479 2480
	if (r5l_load_log(log))
		goto error;

2481
	rcu_assign_pointer(conf->log, log);
2482
	set_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
S
Shaohua Li 已提交
2483
	return 0;
2484

S
Shaohua Li 已提交
2485
error:
S
Shaohua Li 已提交
2486 2487
	md_unregister_thread(&log->reclaim_thread);
reclaim_thread:
2488 2489
	mempool_destroy(log->meta_pool);
out_mempool:
C
Christoph Hellwig 已提交
2490 2491
	bioset_free(log->bs);
io_bs:
2492 2493
	mempool_destroy(log->io_pool);
io_pool:
S
Shaohua Li 已提交
2494 2495 2496 2497 2498 2499 2500 2501
	kmem_cache_destroy(log->io_kc);
io_kc:
	kfree(log);
	return -EINVAL;
}

void r5l_exit_log(struct r5l_log *log)
{
S
Shaohua Li 已提交
2502
	md_unregister_thread(&log->reclaim_thread);
2503
	mempool_destroy(log->meta_pool);
C
Christoph Hellwig 已提交
2504
	bioset_free(log->bs);
2505
	mempool_destroy(log->io_pool);
S
Shaohua Li 已提交
2506 2507 2508
	kmem_cache_destroy(log->io_kc);
	kfree(log);
}