linux-imx

/*

 * Copyright (C) 2015 Shaohua Li <shli@fb.com>

 * Copyright (C) 2016 Song Liu <songliubraving@fb.com>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms and conditions of the GNU General Public License,

 * 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 <linux/kthread.h>

#include <linux/types.h>

#include "md.h"

#include "raid5.h"

#include "md-bitmap.h"

#include "raid5-log.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)

#define BLOCK_SECTOR_SHIFT (3)

​

/*

 * 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

 */

#define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */

#define RECLAIM_MAX_FREE_SPACE_SHIFT (2)

​

/* wake up reclaim thread periodically */

#define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ)

/* start flush with these full stripes */

#define R5C_FULL_STRIPE_FLUSH_BATCH(conf) (conf->max_nr_stripes / 4)

/* reclaim stripes in groups */

#define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2)

​

/*

 * 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

​

static char *r5c_journal_mode_str[] = {"write-through",

                       "write-back"};

/*

 * raid5 cache state machine

 *

 * With the 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

 */

​

struct r5l_log {

    struct md_rdev *rdev;