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dm-raid.c

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    dm-raid.c 114.91 KiB
    /*
     * Copyright (C) 2010-2011 Neil Brown
     * Copyright (C) 2010-2017 Red Hat, Inc. All rights reserved.
     *
     * This file is released under the GPL.
     */
    
    #include <linux/slab.h>
    #include <linux/module.h>
    
    #include "md.h"
    #include "raid1.h"
    #include "raid5.h"
    #include "raid10.h"
    #include "md-bitmap.h"
    
    #include <linux/device-mapper.h>
    
    #define DM_MSG_PREFIX "raid"
    #define	MAX_RAID_DEVICES	253 /* md-raid kernel limit */
    
    /*
     * Minimum sectors of free reshape space per raid device
     */
    #define	MIN_FREE_RESHAPE_SPACE to_sector(4*4096)
    
    /*
     * Minimum journal space 4 MiB in sectors.
     */
    #define	MIN_RAID456_JOURNAL_SPACE (4*2048)
    
    static bool devices_handle_discard_safely = false;
    
    /*
     * The following flags are used by dm-raid.c to set up the array state.
     * They must be cleared before md_run is called.
     */
    #define FirstUse 10		/* rdev flag */
    
    struct raid_dev {
    	/*
    	 * Two DM devices, one to hold metadata and one to hold the
    	 * actual data/parity.	The reason for this is to not confuse
    	 * ti->len and give more flexibility in altering size and
    	 * characteristics.
    	 *
    	 * While it is possible for this device to be associated
    	 * with a different physical device than the data_dev, it
    	 * is intended for it to be the same.
    	 *    |--------- Physical Device ---------|
    	 *    |- meta_dev -|------ data_dev ------|
    	 */
    	struct dm_dev *meta_dev;
    	struct dm_dev *data_dev;
    	struct md_rdev rdev;
    };
    
    /*
     * Bits for establishing rs->ctr_flags
     *
     * 1 = no flag value
     * 2 = flag with value
     */
    #define __CTR_FLAG_SYNC			0  /* 1 */ /* Not with raid0! */
    #define __CTR_FLAG_NOSYNC		1  /* 1 */ /* Not with raid0! */
    #define __CTR_FLAG_REBUILD		2  /* 2 */ /* Not with raid0! */
    #define __CTR_FLAG_DAEMON_SLEEP		3  /* 2 */ /* Not with raid0! */
    #define __CTR_FLAG_MIN_RECOVERY_RATE	4  /* 2 */ /* Not with raid0! */
    #define __CTR_FLAG_MAX_RECOVERY_RATE	5  /* 2 */ /* Not with raid0! */
    #define __CTR_FLAG_MAX_WRITE_BEHIND	6  /* 2 */ /* Only with raid1! */
    #define __CTR_FLAG_WRITE_MOSTLY		7  /* 2 */ /* Only with raid1! */
    #define __CTR_FLAG_STRIPE_CACHE		8  /* 2 */ /* Only with raid4/5/6! */
    #define __CTR_FLAG_REGION_SIZE		9  /* 2 */ /* Not with raid0! */
    #define __CTR_FLAG_RAID10_COPIES	10 /* 2 */ /* Only with raid10 */
    #define __CTR_FLAG_RAID10_FORMAT	11 /* 2 */ /* Only with raid10 */
    /* New for v1.9.0 */
    #define __CTR_FLAG_DELTA_DISKS		12 /* 2 */ /* Only with reshapable raid1/4/5/6/10! */
    #define __CTR_FLAG_DATA_OFFSET		13 /* 2 */ /* Only with reshapable raid4/5/6/10! */
    #define __CTR_FLAG_RAID10_USE_NEAR_SETS 14 /* 2 */ /* Only with raid10! */
    
    /* New for v1.10.0 */
    #define __CTR_FLAG_JOURNAL_DEV		15 /* 2 */ /* Only with raid4/5/6 (journal device)! */
    
    /* New for v1.11.1 */
    #define __CTR_FLAG_JOURNAL_MODE		16 /* 2 */ /* Only with raid4/5/6 (journal mode)! */
    
    /*
     * Flags for rs->ctr_flags field.
     */
    #define CTR_FLAG_SYNC			(1 << __CTR_FLAG_SYNC)
    #define CTR_FLAG_NOSYNC			(1 << __CTR_FLAG_NOSYNC)
    #define CTR_FLAG_REBUILD		(1 << __CTR_FLAG_REBUILD)
    #define CTR_FLAG_DAEMON_SLEEP		(1 << __CTR_FLAG_DAEMON_SLEEP)
    #define CTR_FLAG_MIN_RECOVERY_RATE	(1 << __CTR_FLAG_MIN_RECOVERY_RATE)
    #define CTR_FLAG_MAX_RECOVERY_RATE	(1 << __CTR_FLAG_MAX_RECOVERY_RATE)
    #define CTR_FLAG_MAX_WRITE_BEHIND	(1 << __CTR_FLAG_MAX_WRITE_BEHIND)
    #define CTR_FLAG_WRITE_MOSTLY		(1 << __CTR_FLAG_WRITE_MOSTLY)
    #define CTR_FLAG_STRIPE_CACHE		(1 << __CTR_FLAG_STRIPE_CACHE)
    #define CTR_FLAG_REGION_SIZE		(1 << __CTR_FLAG_REGION_SIZE)
    #define CTR_FLAG_RAID10_COPIES		(1 << __CTR_FLAG_RAID10_COPIES)
    #define CTR_FLAG_RAID10_FORMAT		(1 << __CTR_FLAG_RAID10_FORMAT)
    #define CTR_FLAG_DELTA_DISKS		(1 << __CTR_FLAG_DELTA_DISKS)
    #define CTR_FLAG_DATA_OFFSET		(1 << __CTR_FLAG_DATA_OFFSET)
    #define CTR_FLAG_RAID10_USE_NEAR_SETS	(1 << __CTR_FLAG_RAID10_USE_NEAR_SETS)
    #define CTR_FLAG_JOURNAL_DEV		(1 << __CTR_FLAG_JOURNAL_DEV)
    #define CTR_FLAG_JOURNAL_MODE		(1 << __CTR_FLAG_JOURNAL_MODE)
    
    #define RESUME_STAY_FROZEN_FLAGS (CTR_FLAG_DELTA_DISKS | CTR_FLAG_DATA_OFFSET)
    
    /*
     * Definitions of various constructor flags to
     * be used in checks of valid / invalid flags
     * per raid level.
     */
    /* Define all any sync flags */
    #define	CTR_FLAGS_ANY_SYNC		(CTR_FLAG_SYNC | CTR_FLAG_NOSYNC)
    
    /* Define flags for options without argument (e.g. 'nosync') */
    #define	CTR_FLAG_OPTIONS_NO_ARGS	(CTR_FLAGS_ANY_SYNC | \
    					 CTR_FLAG_RAID10_USE_NEAR_SETS)
    
    /* Define flags for options with one argument (e.g. 'delta_disks +2') */
    #define CTR_FLAG_OPTIONS_ONE_ARG (CTR_FLAG_REBUILD | \
    				  CTR_FLAG_WRITE_MOSTLY | \
    				  CTR_FLAG_DAEMON_SLEEP | \
    				  CTR_FLAG_MIN_RECOVERY_RATE | \
    				  CTR_FLAG_MAX_RECOVERY_RATE | \
    				  CTR_FLAG_MAX_WRITE_BEHIND | \
    				  CTR_FLAG_STRIPE_CACHE | \
    				  CTR_FLAG_REGION_SIZE | \
    				  CTR_FLAG_RAID10_COPIES | \
    				  CTR_FLAG_RAID10_FORMAT | \
    				  CTR_FLAG_DELTA_DISKS | \
    				  CTR_FLAG_DATA_OFFSET)
    
    /* Valid options definitions per raid level... */
    
    /* "raid0" does only accept data offset */
    #define RAID0_VALID_FLAGS	(CTR_FLAG_DATA_OFFSET)
    
    /* "raid1" does not accept stripe cache, data offset, delta_disks or any raid10 options */
    #define RAID1_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
    				 CTR_FLAG_REBUILD | \
    				 CTR_FLAG_WRITE_MOSTLY | \
    				 CTR_FLAG_DAEMON_SLEEP | \
    				 CTR_FLAG_MIN_RECOVERY_RATE | \
    				 CTR_FLAG_MAX_RECOVERY_RATE | \
    				 CTR_FLAG_MAX_WRITE_BEHIND | \
    				 CTR_FLAG_REGION_SIZE | \
    				 CTR_FLAG_DELTA_DISKS | \
    				 CTR_FLAG_DATA_OFFSET)
    
    /* "raid10" does not accept any raid1 or stripe cache options */
    #define RAID10_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
    				 CTR_FLAG_REBUILD | \
    				 CTR_FLAG_DAEMON_SLEEP | \
    				 CTR_FLAG_MIN_RECOVERY_RATE | \
    				 CTR_FLAG_MAX_RECOVERY_RATE | \
    				 CTR_FLAG_REGION_SIZE | \
    				 CTR_FLAG_RAID10_COPIES | \
    				 CTR_FLAG_RAID10_FORMAT | \
    				 CTR_FLAG_DELTA_DISKS | \
    				 CTR_FLAG_DATA_OFFSET | \
    				 CTR_FLAG_RAID10_USE_NEAR_SETS)
    
    /*
     * "raid4/5/6" do not accept any raid1 or raid10 specific options
     *
     * "raid6" does not accept "nosync", because it is not guaranteed
     * that both parity and q-syndrome are being written properly with
     * any writes
     */
    #define RAID45_VALID_FLAGS	(CTR_FLAGS_ANY_SYNC | \
    				 CTR_FLAG_REBUILD | \
    				 CTR_FLAG_DAEMON_SLEEP | \
    				 CTR_FLAG_MIN_RECOVERY_RATE | \
    				 CTR_FLAG_MAX_RECOVERY_RATE | \
    				 CTR_FLAG_STRIPE_CACHE | \
    				 CTR_FLAG_REGION_SIZE | \
    				 CTR_FLAG_DELTA_DISKS | \
    				 CTR_FLAG_DATA_OFFSET | \
    				 CTR_FLAG_JOURNAL_DEV | \
    				 CTR_FLAG_JOURNAL_MODE)
    
    #define RAID6_VALID_FLAGS	(CTR_FLAG_SYNC | \
    				 CTR_FLAG_REBUILD | \
    				 CTR_FLAG_DAEMON_SLEEP | \
    				 CTR_FLAG_MIN_RECOVERY_RATE | \
    				 CTR_FLAG_MAX_RECOVERY_RATE | \
    				 CTR_FLAG_STRIPE_CACHE | \
    				 CTR_FLAG_REGION_SIZE | \
    				 CTR_FLAG_DELTA_DISKS | \
    				 CTR_FLAG_DATA_OFFSET | \
    				 CTR_FLAG_JOURNAL_DEV | \
    				 CTR_FLAG_JOURNAL_MODE)
    /* ...valid options definitions per raid level */
    
    /*
     * Flags for rs->runtime_flags field
     * (RT_FLAG prefix meaning "runtime flag")
     *
     * These are all internal and used to define runtime state,
     * e.g. to prevent another resume from preresume processing
     * the raid set all over again.
     */
    #define RT_FLAG_RS_PRERESUMED		0
    #define RT_FLAG_RS_RESUMED		1
    #define RT_FLAG_RS_BITMAP_LOADED	2
    #define RT_FLAG_UPDATE_SBS		3
    #define RT_FLAG_RESHAPE_RS		4
    #define RT_FLAG_RS_SUSPENDED		5
    
    /* Array elements of 64 bit needed for rebuild/failed disk bits */
    #define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
    
    /*
     * raid set level, layout and chunk sectors backup/restore
     */
    struct rs_layout {
    	int new_level;
    	int new_layout;
    	int new_chunk_sectors;
    };
    
    struct raid_set {
    	struct dm_target *ti;
    
    	uint32_t bitmap_loaded;
    	uint32_t stripe_cache_entries;
    	unsigned long ctr_flags;
    	unsigned long runtime_flags;
    
    	uint64_t rebuild_disks[DISKS_ARRAY_ELEMS];
    
    	int raid_disks;
    	int delta_disks;
    	int data_offset;
    	int raid10_copies;
    	int requested_bitmap_chunk_sectors;
    
    	struct mddev md;
    	struct raid_type *raid_type;
    	struct dm_target_callbacks callbacks;
    
    	/* Optional raid4/5/6 journal device */
    	struct journal_dev {
    		struct dm_dev *dev;
    		struct md_rdev rdev;
    		int mode;
    	} journal_dev;
    
    	struct raid_dev dev[0];
    };
    
    static void rs_config_backup(struct raid_set *rs, struct rs_layout *l)
    {
    	struct mddev *mddev = &rs->md;
    
    	l->new_level = mddev->new_level;
    	l->new_layout = mddev->new_layout;
    	l->new_chunk_sectors = mddev->new_chunk_sectors;
    }
    
    static void rs_config_restore(struct raid_set *rs, struct rs_layout *l)
    {
    	struct mddev *mddev = &rs->md;
    
    	mddev->new_level = l->new_level;
    	mddev->new_layout = l->new_layout;
    	mddev->new_chunk_sectors = l->new_chunk_sectors;
    }
    
    /* raid10 algorithms (i.e. formats) */
    #define	ALGORITHM_RAID10_DEFAULT	0
    #define	ALGORITHM_RAID10_NEAR		1
    #define	ALGORITHM_RAID10_OFFSET		2
    #define	ALGORITHM_RAID10_FAR		3
    
    /* Supported raid types and properties. */
    static struct raid_type {
    	const char *name;		/* RAID algorithm. */
    	const char *descr;		/* Descriptor text for logging. */
    	const unsigned int parity_devs;	/* # of parity devices. */
    	const unsigned int minimal_devs;/* minimal # of devices in set. */
    	const unsigned int level;	/* RAID level. */
    	const unsigned int algorithm;	/* RAID algorithm. */
    } raid_types[] = {
    	{"raid0",	  "raid0 (striping)",			    0, 2, 0,  0 /* NONE */},
    	{"raid1",	  "raid1 (mirroring)",			    0, 2, 1,  0 /* NONE */},
    	{"raid10_far",	  "raid10 far (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_FAR},
    	{"raid10_offset", "raid10 offset (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_OFFSET},
    	{"raid10_near",	  "raid10 near (striped mirrors)",	    0, 2, 10, ALGORITHM_RAID10_NEAR},
    	{"raid10",	  "raid10 (striped mirrors)",		    0, 2, 10, ALGORITHM_RAID10_DEFAULT},
    	{"raid4",	  "raid4 (dedicated first parity disk)",    1, 2, 5,  ALGORITHM_PARITY_0}, /* raid4 layout = raid5_0 */
    	{"raid5_n",	  "raid5 (dedicated last parity disk)",	    1, 2, 5,  ALGORITHM_PARITY_N},
    	{"raid5_ls",	  "raid5 (left symmetric)",		    1, 2, 5,  ALGORITHM_LEFT_SYMMETRIC},
    	{"raid5_rs",	  "raid5 (right symmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_SYMMETRIC},
    	{"raid5_la",	  "raid5 (left asymmetric)",		    1, 2, 5,  ALGORITHM_LEFT_ASYMMETRIC},
    	{"raid5_ra",	  "raid5 (right asymmetric)",		    1, 2, 5,  ALGORITHM_RIGHT_ASYMMETRIC},
    	{"raid6_zr",	  "raid6 (zero restart)",		    2, 4, 6,  ALGORITHM_ROTATING_ZERO_RESTART},
    	{"raid6_nr",	  "raid6 (N restart)",			    2, 4, 6,  ALGORITHM_ROTATING_N_RESTART},
    	{"raid6_nc",	  "raid6 (N continue)",			    2, 4, 6,  ALGORITHM_ROTATING_N_CONTINUE},
    	{"raid6_n_6",	  "raid6 (dedicated parity/Q n/6)",	    2, 4, 6,  ALGORITHM_PARITY_N_6},
    	{"raid6_ls_6",	  "raid6 (left symmetric dedicated Q 6)",   2, 4, 6,  ALGORITHM_LEFT_SYMMETRIC_6},
    	{"raid6_rs_6",	  "raid6 (right symmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_RIGHT_SYMMETRIC_6},
    	{"raid6_la_6",	  "raid6 (left asymmetric dedicated Q 6)",  2, 4, 6,  ALGORITHM_LEFT_ASYMMETRIC_6},
    	{"raid6_ra_6",	  "raid6 (right asymmetric dedicated Q 6)", 2, 4, 6,  ALGORITHM_RIGHT_ASYMMETRIC_6}
    };
    
    /* True, if @v is in inclusive range [@min, @max] */
    static bool __within_range(long v, long min, long max)
    {
    	return v >= min && v <= max;
    }
    
    /* All table line arguments are defined here */
    static struct arg_name_flag {
    	const unsigned long flag;
    	const char *name;
    } __arg_name_flags[] = {
    	{ CTR_FLAG_SYNC, "sync"},
    	{ CTR_FLAG_NOSYNC, "nosync"},
    	{ CTR_FLAG_REBUILD, "rebuild"},
    	{ CTR_FLAG_DAEMON_SLEEP, "daemon_sleep"},
    	{ CTR_FLAG_MIN_RECOVERY_RATE, "min_recovery_rate"},
    	{ CTR_FLAG_MAX_RECOVERY_RATE, "max_recovery_rate"},
    	{ CTR_FLAG_MAX_WRITE_BEHIND, "max_write_behind"},
    	{ CTR_FLAG_WRITE_MOSTLY, "write_mostly"},
    	{ CTR_FLAG_STRIPE_CACHE, "stripe_cache"},
    	{ CTR_FLAG_REGION_SIZE, "region_size"},
    	{ CTR_FLAG_RAID10_COPIES, "raid10_copies"},
    	{ CTR_FLAG_RAID10_FORMAT, "raid10_format"},
    	{ CTR_FLAG_DATA_OFFSET, "data_offset"},
    	{ CTR_FLAG_DELTA_DISKS, "delta_disks"},
    	{ CTR_FLAG_RAID10_USE_NEAR_SETS, "raid10_use_near_sets"},
    	{ CTR_FLAG_JOURNAL_DEV, "journal_dev" },
    	{ CTR_FLAG_JOURNAL_MODE, "journal_mode" },
    };
    
    /* Return argument name string for given @flag */
    static const char *dm_raid_arg_name_by_flag(const uint32_t flag)
    {
    	if (hweight32(flag) == 1) {
    		struct arg_name_flag *anf = __arg_name_flags + ARRAY_SIZE(__arg_name_flags);
    
    		while (anf-- > __arg_name_flags)
    			if (flag & anf->flag)
    				return anf->name;
    
    	} else
    		DMERR("%s called with more than one flag!", __func__);
    
    	return NULL;
    }
    
    /* Define correlation of raid456 journal cache modes and dm-raid target line parameters */
    static struct {
    	const int mode;
    	const char *param;
    } _raid456_journal_mode[] = {
    	{ R5C_JOURNAL_MODE_WRITE_THROUGH , "writethrough" },
    	{ R5C_JOURNAL_MODE_WRITE_BACK    , "writeback" }
    };
    
    /* Return MD raid4/5/6 journal mode for dm @journal_mode one */
    static int dm_raid_journal_mode_to_md(const char *mode)
    {
    	int m = ARRAY_SIZE(_raid456_journal_mode);
    
    	while (m--)
    		if (!strcasecmp(mode, _raid456_journal_mode[m].param))
    			return _raid456_journal_mode[m].mode;
    
    	return -EINVAL;
    }
    
    /* Return dm-raid raid4/5/6 journal mode string for @mode */
    static const char *md_journal_mode_to_dm_raid(const int mode)
    {
    	int m = ARRAY_SIZE(_raid456_journal_mode);
    
    	while (m--)
    		if (mode == _raid456_journal_mode[m].mode)
    			return _raid456_journal_mode[m].param;
    
    	return "unknown";
    }
    
    /*
     * Bool helpers to test for various raid levels of a raid set.
     * It's level as reported by the superblock rather than
     * the requested raid_type passed to the constructor.
     */
    /* Return true, if raid set in @rs is raid0 */
    static bool rs_is_raid0(struct raid_set *rs)
    {
    	return !rs->md.level;
    }
    
    /* Return true, if raid set in @rs is raid1 */
    static bool rs_is_raid1(struct raid_set *rs)
    {
    	return rs->md.level == 1;
    }
    
    /* Return true, if raid set in @rs is raid10 */
    static bool rs_is_raid10(struct raid_set *rs)
    {
    	return rs->md.level == 10;
    }
    
    /* Return true, if raid set in @rs is level 6 */
    static bool rs_is_raid6(struct raid_set *rs)
    {
    	return rs->md.level == 6;
    }
    
    /* Return true, if raid set in @rs is level 4, 5 or 6 */
    static bool rs_is_raid456(struct raid_set *rs)
    {
    	return __within_range(rs->md.level, 4, 6);
    }
    
    /* Return true, if raid set in @rs is reshapable */
    static bool __is_raid10_far(int layout);
    static bool rs_is_reshapable(struct raid_set *rs)
    {
    	return rs_is_raid456(rs) ||
    	       (rs_is_raid10(rs) && !__is_raid10_far(rs->md.new_layout));
    }
    
    /* Return true, if raid set in @rs is recovering */
    static bool rs_is_recovering(struct raid_set *rs)
    {
    	return rs->md.recovery_cp < rs->md.dev_sectors;
    }
    
    /* Return true, if raid set in @rs is reshaping */
    static bool rs_is_reshaping(struct raid_set *rs)
    {
    	return rs->md.reshape_position != MaxSector;
    }
    
    /*
     * bool helpers to test for various raid levels of a raid type @rt
     */
    
    /* Return true, if raid type in @rt is raid0 */
    static bool rt_is_raid0(struct raid_type *rt)
    {
    	return !rt->level;
    }
    
    /* Return true, if raid type in @rt is raid1 */
    static bool rt_is_raid1(struct raid_type *rt)
    {
    	return rt->level == 1;
    }
    
    /* Return true, if raid type in @rt is raid10 */
    static bool rt_is_raid10(struct raid_type *rt)
    {
    	return rt->level == 10;
    }
    
    /* Return true, if raid type in @rt is raid4/5 */
    static bool rt_is_raid45(struct raid_type *rt)
    {
    	return __within_range(rt->level, 4, 5);
    }
    
    /* Return true, if raid type in @rt is raid6 */
    static bool rt_is_raid6(struct raid_type *rt)
    {
    	return rt->level == 6;
    }
    
    /* Return true, if raid type in @rt is raid4/5/6 */
    static bool rt_is_raid456(struct raid_type *rt)
    {
    	return __within_range(rt->level, 4, 6);
    }
    /* END: raid level bools */
    
    /* Return valid ctr flags for the raid level of @rs */
    static unsigned long __valid_flags(struct raid_set *rs)
    {
    	if (rt_is_raid0(rs->raid_type))
    		return RAID0_VALID_FLAGS;
    	else if (rt_is_raid1(rs->raid_type))
    		return RAID1_VALID_FLAGS;
    	else if (rt_is_raid10(rs->raid_type))
    		return RAID10_VALID_FLAGS;
    	else if (rt_is_raid45(rs->raid_type))
    		return RAID45_VALID_FLAGS;
    	else if (rt_is_raid6(rs->raid_type))
    		return RAID6_VALID_FLAGS;
    
    	return 0;
    }
    
    /*
     * Check for valid flags set on @rs
     *
     * Has to be called after parsing of the ctr flags!
     */
    static int rs_check_for_valid_flags(struct raid_set *rs)
    {
    	if (rs->ctr_flags & ~__valid_flags(rs)) {
    		rs->ti->error = "Invalid flags combination";
    		return -EINVAL;
    	}
    
    	return 0;
    }
    
    /* MD raid10 bit definitions and helpers */
    #define RAID10_OFFSET			(1 << 16) /* stripes with data copies area adjacent on devices */
    #define RAID10_BROCKEN_USE_FAR_SETS	(1 << 17) /* Broken in raid10.c: use sets instead of whole stripe rotation */
    #define RAID10_USE_FAR_SETS		(1 << 18) /* Use sets instead of whole stripe rotation */
    #define RAID10_FAR_COPIES_SHIFT		8	  /* raid10 # far copies shift (2nd byte of layout) */
    
    /* Return md raid10 near copies for @layout */
    static unsigned int __raid10_near_copies(int layout)
    {
    	return layout & 0xFF;
    }
    
    /* Return md raid10 far copies for @layout */
    static unsigned int __raid10_far_copies(int layout)
    {
    	return __raid10_near_copies(layout >> RAID10_FAR_COPIES_SHIFT);
    }
    
    /* Return true if md raid10 offset for @layout */
    static bool __is_raid10_offset(int layout)
    {
    	return !!(layout & RAID10_OFFSET);
    }
    
    /* Return true if md raid10 near for @layout */
    static bool __is_raid10_near(int layout)
    {
    	return !__is_raid10_offset(layout) && __raid10_near_copies(layout) > 1;
    }
    
    /* Return true if md raid10 far for @layout */
    static bool __is_raid10_far(int layout)
    {
    	return !__is_raid10_offset(layout) && __raid10_far_copies(layout) > 1;
    }
    
    /* Return md raid10 layout string for @layout */
    static const char *raid10_md_layout_to_format(int layout)
    {
    	/*
    	 * Bit 16 stands for "offset"
    	 * (i.e. adjacent stripes hold copies)
    	 *
    	 * Refer to MD's raid10.c for details
    	 */
    	if (__is_raid10_offset(layout))
    		return "offset";
    
    	if (__raid10_near_copies(layout) > 1)
    		return "near";
    
    	if (__raid10_far_copies(layout) > 1)
    		return "far";
    
    	return "unknown";
    }
    
    /* Return md raid10 algorithm for @name */
    static int raid10_name_to_format(const char *name)
    {
    	if (!strcasecmp(name, "near"))
    		return ALGORITHM_RAID10_NEAR;
    	else if (!strcasecmp(name, "offset"))
    		return ALGORITHM_RAID10_OFFSET;
    	else if (!strcasecmp(name, "far"))
    		return ALGORITHM_RAID10_FAR;
    
    	return -EINVAL;
    }
    
    /* Return md raid10 copies for @layout */
    static unsigned int raid10_md_layout_to_copies(int layout)
    {
    	return max(__raid10_near_copies(layout), __raid10_far_copies(layout));
    }
    
    /* Return md raid10 format id for @format string */
    static int raid10_format_to_md_layout(struct raid_set *rs,
    				      unsigned int algorithm,
    				      unsigned int copies)
    {
    	unsigned int n = 1, f = 1, r = 0;
    
    	/*
    	 * MD resilienece flaw:
    	 *
    	 * enabling use_far_sets for far/offset formats causes copies
    	 * to be colocated on the same devs together with their origins!
    	 *
    	 * -> disable it for now in the definition above
    	 */
    	if (algorithm == ALGORITHM_RAID10_DEFAULT ||
    	    algorithm == ALGORITHM_RAID10_NEAR)
    		n = copies;
    
    	else if (algorithm == ALGORITHM_RAID10_OFFSET) {
    		f = copies;
    		r = RAID10_OFFSET;
    		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
    			r |= RAID10_USE_FAR_SETS;
    
    	} else if (algorithm == ALGORITHM_RAID10_FAR) {
    		f = copies;
    		r = !RAID10_OFFSET;
    		if (!test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags))
    			r |= RAID10_USE_FAR_SETS;
    
    	} else
    		return -EINVAL;
    
    	return r | (f << RAID10_FAR_COPIES_SHIFT) | n;
    }
    /* END: MD raid10 bit definitions and helpers */
    
    /* Check for any of the raid10 algorithms */
    static bool __got_raid10(struct raid_type *rtp, const int layout)
    {
    	if (rtp->level == 10) {
    		switch (rtp->algorithm) {
    		case ALGORITHM_RAID10_DEFAULT:
    		case ALGORITHM_RAID10_NEAR:
    			return __is_raid10_near(layout);
    		case ALGORITHM_RAID10_OFFSET:
    			return __is_raid10_offset(layout);
    		case ALGORITHM_RAID10_FAR:
    			return __is_raid10_far(layout);
    		default:
    			break;
    		}
    	}
    
    	return false;
    }
    
    /* Return raid_type for @name */
    static struct raid_type *get_raid_type(const char *name)
    {
    	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
    
    	while (rtp-- > raid_types)
    		if (!strcasecmp(rtp->name, name))
    			return rtp;
    
    	return NULL;
    }
    
    /* Return raid_type for @name based derived from @level and @layout */
    static struct raid_type *get_raid_type_by_ll(const int level, const int layout)
    {
    	struct raid_type *rtp = raid_types + ARRAY_SIZE(raid_types);
    
    	while (rtp-- > raid_types) {
    		/* RAID10 special checks based on @layout flags/properties */
    		if (rtp->level == level &&
    		    (__got_raid10(rtp, layout) || rtp->algorithm == layout))
    			return rtp;
    	}
    
    	return NULL;
    }
    
    /* Adjust rdev sectors */
    static void rs_set_rdev_sectors(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    	struct md_rdev *rdev;
    
    	/*
    	 * raid10 sets rdev->sector to the device size, which
    	 * is unintended in case of out-of-place reshaping
    	 */
    	rdev_for_each(rdev, mddev)
    		if (!test_bit(Journal, &rdev->flags))
    			rdev->sectors = mddev->dev_sectors;
    }
    
    /*
     * Change bdev capacity of @rs in case of a disk add/remove reshape
     */
    static void rs_set_capacity(struct raid_set *rs)
    {
    	struct gendisk *gendisk = dm_disk(dm_table_get_md(rs->ti->table));
    
    	set_capacity(gendisk, rs->md.array_sectors);
    	revalidate_disk(gendisk);
    }
    
    /*
     * Set the mddev properties in @rs to the current
     * ones retrieved from the freshest superblock
     */
    static void rs_set_cur(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    
    	mddev->new_level = mddev->level;
    	mddev->new_layout = mddev->layout;
    	mddev->new_chunk_sectors = mddev->chunk_sectors;
    }
    
    /*
     * Set the mddev properties in @rs to the new
     * ones requested by the ctr
     */
    static void rs_set_new(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    
    	mddev->level = mddev->new_level;
    	mddev->layout = mddev->new_layout;
    	mddev->chunk_sectors = mddev->new_chunk_sectors;
    	mddev->raid_disks = rs->raid_disks;
    	mddev->delta_disks = 0;
    }
    
    static struct raid_set *raid_set_alloc(struct dm_target *ti, struct raid_type *raid_type,
    				       unsigned int raid_devs)
    {
    	unsigned int i;
    	struct raid_set *rs;
    
    	if (raid_devs <= raid_type->parity_devs) {
    		ti->error = "Insufficient number of devices";
    		return ERR_PTR(-EINVAL);
    	}
    
    	rs = kzalloc(sizeof(*rs) + raid_devs * sizeof(rs->dev[0]), GFP_KERNEL);
    	if (!rs) {
    		ti->error = "Cannot allocate raid context";
    		return ERR_PTR(-ENOMEM);
    	}
    
    	mddev_init(&rs->md);
    
    	rs->raid_disks = raid_devs;
    	rs->delta_disks = 0;
    
    	rs->ti = ti;
    	rs->raid_type = raid_type;
    	rs->stripe_cache_entries = 256;
    	rs->md.raid_disks = raid_devs;
    	rs->md.level = raid_type->level;
    	rs->md.new_level = rs->md.level;
    	rs->md.layout = raid_type->algorithm;
    	rs->md.new_layout = rs->md.layout;
    	rs->md.delta_disks = 0;
    	rs->md.recovery_cp = MaxSector;
    
    	for (i = 0; i < raid_devs; i++)
    		md_rdev_init(&rs->dev[i].rdev);
    
    	/*
    	 * Remaining items to be initialized by further RAID params:
    	 *  rs->md.persistent
    	 *  rs->md.external
    	 *  rs->md.chunk_sectors
    	 *  rs->md.new_chunk_sectors
    	 *  rs->md.dev_sectors
    	 */
    
    	return rs;
    }
    
    static void raid_set_free(struct raid_set *rs)
    {
    	int i;
    
    	if (rs->journal_dev.dev) {
    		md_rdev_clear(&rs->journal_dev.rdev);
    		dm_put_device(rs->ti, rs->journal_dev.dev);
    	}
    
    	for (i = 0; i < rs->raid_disks; i++) {
    		if (rs->dev[i].meta_dev)
    			dm_put_device(rs->ti, rs->dev[i].meta_dev);
    		md_rdev_clear(&rs->dev[i].rdev);
    		if (rs->dev[i].data_dev)
    			dm_put_device(rs->ti, rs->dev[i].data_dev);
    	}
    
    	kfree(rs);
    }
    
    /*
     * For every device we have two words
     *  <meta_dev>: meta device name or '-' if missing
     *  <data_dev>: data device name or '-' if missing
     *
     * The following are permitted:
     *    - -
     *    - <data_dev>
     *    <meta_dev> <data_dev>
     *
     * The following is not allowed:
     *    <meta_dev> -
     *
     * This code parses those words.  If there is a failure,
     * the caller must use raid_set_free() to unwind the operations.
     */
    static int parse_dev_params(struct raid_set *rs, struct dm_arg_set *as)
    {
    	int i;
    	int rebuild = 0;
    	int metadata_available = 0;
    	int r = 0;
    	const char *arg;
    
    	/* Put off the number of raid devices argument to get to dev pairs */
    	arg = dm_shift_arg(as);
    	if (!arg)
    		return -EINVAL;
    
    	for (i = 0; i < rs->raid_disks; i++) {
    		rs->dev[i].rdev.raid_disk = i;
    
    		rs->dev[i].meta_dev = NULL;
    		rs->dev[i].data_dev = NULL;
    
    		/*
    		 * There are no offsets initially.
    		 * Out of place reshape will set them accordingly.
    		 */
    		rs->dev[i].rdev.data_offset = 0;
    		rs->dev[i].rdev.new_data_offset = 0;
    		rs->dev[i].rdev.mddev = &rs->md;
    
    		arg = dm_shift_arg(as);
    		if (!arg)
    			return -EINVAL;
    
    		if (strcmp(arg, "-")) {
    			r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
    					  &rs->dev[i].meta_dev);
    			if (r) {
    				rs->ti->error = "RAID metadata device lookup failure";
    				return r;
    			}
    
    			rs->dev[i].rdev.sb_page = alloc_page(GFP_KERNEL);
    			if (!rs->dev[i].rdev.sb_page) {
    				rs->ti->error = "Failed to allocate superblock page";
    				return -ENOMEM;
    			}
    		}
    
    		arg = dm_shift_arg(as);
    		if (!arg)
    			return -EINVAL;
    
    		if (!strcmp(arg, "-")) {
    			if (!test_bit(In_sync, &rs->dev[i].rdev.flags) &&
    			    (!rs->dev[i].rdev.recovery_offset)) {
    				rs->ti->error = "Drive designated for rebuild not specified";
    				return -EINVAL;
    			}
    
    			if (rs->dev[i].meta_dev) {
    				rs->ti->error = "No data device supplied with metadata device";
    				return -EINVAL;
    			}
    
    			continue;
    		}
    
    		r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
    				  &rs->dev[i].data_dev);
    		if (r) {
    			rs->ti->error = "RAID device lookup failure";
    			return r;
    		}
    
    		if (rs->dev[i].meta_dev) {
    			metadata_available = 1;
    			rs->dev[i].rdev.meta_bdev = rs->dev[i].meta_dev->bdev;
    		}
    		rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
    		list_add_tail(&rs->dev[i].rdev.same_set, &rs->md.disks);
    		if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
    			rebuild++;
    	}
    
    	if (rs->journal_dev.dev)
    		list_add_tail(&rs->journal_dev.rdev.same_set, &rs->md.disks);
    
    	if (metadata_available) {
    		rs->md.external = 0;
    		rs->md.persistent = 1;
    		rs->md.major_version = 2;
    	} else if (rebuild && !rs->md.recovery_cp) {
    		/*
    		 * Without metadata, we will not be able to tell if the array
    		 * is in-sync or not - we must assume it is not.  Therefore,
    		 * it is impossible to rebuild a drive.
    		 *
    		 * Even if there is metadata, the on-disk information may
    		 * indicate that the array is not in-sync and it will then
    		 * fail at that time.
    		 *
    		 * User could specify 'nosync' option if desperate.
    		 */
    		rs->ti->error = "Unable to rebuild drive while array is not in-sync";
    		return -EINVAL;
    	}
    
    	return 0;
    }
    
    /*
     * validate_region_size
     * @rs
     * @region_size:  region size in sectors.  If 0, pick a size (4MiB default).
     *
     * Set rs->md.bitmap_info.chunksize (which really refers to 'region size').
     * Ensure that (ti->len/region_size < 2^21) - required by MD bitmap.
     *
     * Returns: 0 on success, -EINVAL on failure.
     */
    static int validate_region_size(struct raid_set *rs, unsigned long region_size)
    {
    	unsigned long min_region_size = rs->ti->len / (1 << 21);
    
    	if (rs_is_raid0(rs))
    		return 0;
    
    	if (!region_size) {
    		/*
    		 * Choose a reasonable default.	 All figures in sectors.
    		 */
    		if (min_region_size > (1 << 13)) {
    			/* If not a power of 2, make it the next power of 2 */
    			region_size = roundup_pow_of_two(min_region_size);
    			DMINFO("Choosing default region size of %lu sectors",
    			       region_size);
    		} else {
    			DMINFO("Choosing default region size of 4MiB");
    			region_size = 1 << 13; /* sectors */
    		}
    	} else {
    		/*
    		 * Validate user-supplied value.
    		 */
    		if (region_size > rs->ti->len) {
    			rs->ti->error = "Supplied region size is too large";
    			return -EINVAL;
    		}
    
    		if (region_size < min_region_size) {
    			DMERR("Supplied region_size (%lu sectors) below minimum (%lu)",
    			      region_size, min_region_size);
    			rs->ti->error = "Supplied region size is too small";
    			return -EINVAL;
    		}
    
    		if (!is_power_of_2(region_size)) {
    			rs->ti->error = "Region size is not a power of 2";
    			return -EINVAL;
    		}
    
    		if (region_size < rs->md.chunk_sectors) {
    			rs->ti->error = "Region size is smaller than the chunk size";
    			return -EINVAL;
    		}
    	}
    
    	/*
    	 * Convert sectors to bytes.
    	 */
    	rs->md.bitmap_info.chunksize = to_bytes(region_size);
    
    	return 0;
    }
    
    /*
     * validate_raid_redundancy
     * @rs
     *
     * Determine if there are enough devices in the array that haven't
     * failed (or are being rebuilt) to form a usable array.
     *
     * Returns: 0 on success, -EINVAL on failure.
     */
    static int validate_raid_redundancy(struct raid_set *rs)
    {
    	unsigned int i, rebuild_cnt = 0;
    	unsigned int rebuilds_per_group = 0, copies;
    	unsigned int group_size, last_group_start;
    
    	for (i = 0; i < rs->md.raid_disks; i++)
    		if (!test_bit(In_sync, &rs->dev[i].rdev.flags) ||
    		    !rs->dev[i].rdev.sb_page)
    			rebuild_cnt++;
    
    	switch (rs->raid_type->level) {
    	case 0:
    		break;
    	case 1:
    		if (rebuild_cnt >= rs->md.raid_disks)
    			goto too_many;
    		break;
    	case 4:
    	case 5:
    	case 6:
    		if (rebuild_cnt > rs->raid_type->parity_devs)
    			goto too_many;
    		break;
    	case 10:
    		copies = raid10_md_layout_to_copies(rs->md.new_layout);
    		if (rebuild_cnt < copies)
    			break;
    
    		/*
    		 * It is possible to have a higher rebuild count for RAID10,
    		 * as long as the failed devices occur in different mirror
    		 * groups (i.e. different stripes).
    		 *
    		 * When checking "near" format, make sure no adjacent devices
    		 * have failed beyond what can be handled.  In addition to the
    		 * simple case where the number of devices is a multiple of the
    		 * number of copies, we must also handle cases where the number
    		 * of devices is not a multiple of the number of copies.
    		 * E.g.	   dev1 dev2 dev3 dev4 dev5
    		 *	    A	 A    B	   B	C
    		 *	    C	 D    D	   E	E
    		 */
    		if (__is_raid10_near(rs->md.new_layout)) {
    			for (i = 0; i < rs->md.raid_disks; i++) {
    				if (!(i % copies))
    					rebuilds_per_group = 0;
    				if ((!rs->dev[i].rdev.sb_page ||
    				    !test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
    				    (++rebuilds_per_group >= copies))
    					goto too_many;
    			}
    			break;
    		}
    
    		/*
    		 * When checking "far" and "offset" formats, we need to ensure
    		 * that the device that holds its copy is not also dead or
    		 * being rebuilt.  (Note that "far" and "offset" formats only
    		 * support two copies right now.  These formats also only ever
    		 * use the 'use_far_sets' variant.)
    		 *
    		 * This check is somewhat complicated by the need to account
    		 * for arrays that are not a multiple of (far) copies.	This
    		 * results in the need to treat the last (potentially larger)
    		 * set differently.
    		 */
    		group_size = (rs->md.raid_disks / copies);
    		last_group_start = (rs->md.raid_disks / group_size) - 1;
    		last_group_start *= group_size;
    		for (i = 0; i < rs->md.raid_disks; i++) {
    			if (!(i % copies) && !(i > last_group_start))
    				rebuilds_per_group = 0;
    			if ((!rs->dev[i].rdev.sb_page ||
    			     !test_bit(In_sync, &rs->dev[i].rdev.flags)) &&
    			    (++rebuilds_per_group >= copies))
    					goto too_many;
    		}
    		break;
    	default:
    		if (rebuild_cnt)
    			return -EINVAL;
    	}
    
    	return 0;
    
    too_many:
    	return -EINVAL;
    }
    
    /*
     * Possible arguments are...
     *	<chunk_size> [optional_args]
     *
     * Argument definitions
     *    <chunk_size>			The number of sectors per disk that
     *					will form the "stripe"
     *    [[no]sync]			Force or prevent recovery of the
     *					entire array
     *    [rebuild <idx>]			Rebuild the drive indicated by the index
     *    [daemon_sleep <ms>]		Time between bitmap daemon work to
     *					clear bits
     *    [min_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
     *    [max_recovery_rate <kB/sec/disk>]	Throttle RAID initialization
     *    [write_mostly <idx>]		Indicate a write mostly drive via index
     *    [max_write_behind <sectors>]	See '-write-behind=' (man mdadm)
     *    [stripe_cache <sectors>]		Stripe cache size for higher RAIDs
     *    [region_size <sectors>]		Defines granularity of bitmap
     *    [journal_dev <dev>]		raid4/5/6 journaling deviice
     *    					(i.e. write hole closing log)
     *
     * RAID10-only options:
     *    [raid10_copies <# copies>]	Number of copies.  (Default: 2)
     *    [raid10_format <near|far|offset>] Layout algorithm.  (Default: near)
     */
    static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
    			     unsigned int num_raid_params)
    {
    	int value, raid10_format = ALGORITHM_RAID10_DEFAULT;
    	unsigned int raid10_copies = 2;
    	unsigned int i, write_mostly = 0;
    	unsigned int region_size = 0;
    	sector_t max_io_len;
    	const char *arg, *key;
    	struct raid_dev *rd;
    	struct raid_type *rt = rs->raid_type;
    
    	arg = dm_shift_arg(as);
    	num_raid_params--; /* Account for chunk_size argument */
    
    	if (kstrtoint(arg, 10, &value) < 0) {
    		rs->ti->error = "Bad numerical argument given for chunk_size";
    		return -EINVAL;
    	}
    
    	/*
    	 * First, parse the in-order required arguments
    	 * "chunk_size" is the only argument of this type.
    	 */
    	if (rt_is_raid1(rt)) {
    		if (value)
    			DMERR("Ignoring chunk size parameter for RAID 1");
    		value = 0;
    	} else if (!is_power_of_2(value)) {
    		rs->ti->error = "Chunk size must be a power of 2";
    		return -EINVAL;
    	} else if (value < 8) {
    		rs->ti->error = "Chunk size value is too small";
    		return -EINVAL;
    	}
    
    	rs->md.new_chunk_sectors = rs->md.chunk_sectors = value;
    
    	/*
    	 * We set each individual device as In_sync with a completed
    	 * 'recovery_offset'.  If there has been a device failure or
    	 * replacement then one of the following cases applies:
    	 *
    	 *   1) User specifies 'rebuild'.
    	 *	- Device is reset when param is read.
    	 *   2) A new device is supplied.
    	 *	- No matching superblock found, resets device.
    	 *   3) Device failure was transient and returns on reload.
    	 *	- Failure noticed, resets device for bitmap replay.
    	 *   4) Device hadn't completed recovery after previous failure.
    	 *	- Superblock is read and overrides recovery_offset.
    	 *
    	 * What is found in the superblocks of the devices is always
    	 * authoritative, unless 'rebuild' or '[no]sync' was specified.
    	 */
    	for (i = 0; i < rs->raid_disks; i++) {
    		set_bit(In_sync, &rs->dev[i].rdev.flags);
    		rs->dev[i].rdev.recovery_offset = MaxSector;
    	}
    
    	/*
    	 * Second, parse the unordered optional arguments
    	 */
    	for (i = 0; i < num_raid_params; i++) {
    		key = dm_shift_arg(as);
    		if (!key) {
    			rs->ti->error = "Not enough raid parameters given";
    			return -EINVAL;
    		}
    
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC))) {
    			if (test_and_set_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
    				rs->ti->error = "Only one 'nosync' argument allowed";
    				return -EINVAL;
    			}
    			continue;
    		}
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_SYNC))) {
    			if (test_and_set_bit(__CTR_FLAG_SYNC, &rs->ctr_flags)) {
    				rs->ti->error = "Only one 'sync' argument allowed";
    				return -EINVAL;
    			}
    			continue;
    		}
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_USE_NEAR_SETS))) {
    			if (test_and_set_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
    				rs->ti->error = "Only one 'raid10_use_new_sets' argument allowed";
    				return -EINVAL;
    			}
    			continue;
    		}
    
    		arg = dm_shift_arg(as);
    		i++; /* Account for the argument pairs */
    		if (!arg) {
    			rs->ti->error = "Wrong number of raid parameters given";
    			return -EINVAL;
    		}
    
    		/*
    		 * Parameters that take a string value are checked here.
    		 */
    		/* "raid10_format {near|offset|far} */
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT))) {
    			if (test_and_set_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags)) {
    				rs->ti->error = "Only one 'raid10_format' argument pair allowed";
    				return -EINVAL;
    			}
    			if (!rt_is_raid10(rt)) {
    				rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
    				return -EINVAL;
    			}
    			raid10_format = raid10_name_to_format(arg);
    			if (raid10_format < 0) {
    				rs->ti->error = "Invalid 'raid10_format' value given";
    				return raid10_format;
    			}
    			continue;
    		}
    
    		/* "journal_dev <dev>" */
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_DEV))) {
    			int r;
    			struct md_rdev *jdev;
    
    			if (test_and_set_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
    				rs->ti->error = "Only one raid4/5/6 set journaling device allowed";
    				return -EINVAL;
    			}
    			if (!rt_is_raid456(rt)) {
    				rs->ti->error = "'journal_dev' is an invalid parameter for this RAID type";
    				return -EINVAL;
    			}
    			r = dm_get_device(rs->ti, arg, dm_table_get_mode(rs->ti->table),
    					  &rs->journal_dev.dev);
    			if (r) {
    				rs->ti->error = "raid4/5/6 journal device lookup failure";
    				return r;
    			}
    			jdev = &rs->journal_dev.rdev;
    			md_rdev_init(jdev);
    			jdev->mddev = &rs->md;
    			jdev->bdev = rs->journal_dev.dev->bdev;
    			jdev->sectors = to_sector(i_size_read(jdev->bdev->bd_inode));
    			if (jdev->sectors < MIN_RAID456_JOURNAL_SPACE) {
    				rs->ti->error = "No space for raid4/5/6 journal";
    				return -ENOSPC;
    			}
    			rs->journal_dev.mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
    			set_bit(Journal, &jdev->flags);
    			continue;
    		}
    
    		/* "journal_mode <mode>" ("journal_dev" mandatory!) */
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_MODE))) {
    			int r;
    
    			if (!test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
    				rs->ti->error = "raid4/5/6 'journal_mode' is invalid without 'journal_dev'";
    				return -EINVAL;
    			}
    			if (test_and_set_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags)) {
    				rs->ti->error = "Only one raid4/5/6 'journal_mode' argument allowed";
    				return -EINVAL;
    			}
    			r = dm_raid_journal_mode_to_md(arg);
    			if (r < 0) {
    				rs->ti->error = "Invalid 'journal_mode' argument";
    				return r;
    			}
    			rs->journal_dev.mode = r;
    			continue;
    		}
    
    		/*
    		 * Parameters with number values from here on.
    		 */
    		if (kstrtoint(arg, 10, &value) < 0) {
    			rs->ti->error = "Bad numerical argument given in raid params";
    			return -EINVAL;
    		}
    
    		if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD))) {
    			/*
    			 * "rebuild" is being passed in by userspace to provide
    			 * indexes of replaced devices and to set up additional
    			 * devices on raid level takeover.
    			 */
    			if (!__within_range(value, 0, rs->raid_disks - 1)) {
    				rs->ti->error = "Invalid rebuild index given";
    				return -EINVAL;
    			}
    
    			if (test_and_set_bit(value, (void *) rs->rebuild_disks)) {
    				rs->ti->error = "rebuild for this index already given";
    				return -EINVAL;
    			}
    
    			rd = rs->dev + value;
    			clear_bit(In_sync, &rd->rdev.flags);
    			clear_bit(Faulty, &rd->rdev.flags);
    			rd->rdev.recovery_offset = 0;
    			set_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags);
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY))) {
    			if (!rt_is_raid1(rt)) {
    				rs->ti->error = "write_mostly option is only valid for RAID1";
    				return -EINVAL;
    			}
    
    			if (!__within_range(value, 0, rs->md.raid_disks - 1)) {
    				rs->ti->error = "Invalid write_mostly index given";
    				return -EINVAL;
    			}
    
    			write_mostly++;
    			set_bit(WriteMostly, &rs->dev[value].rdev.flags);
    			set_bit(__CTR_FLAG_WRITE_MOSTLY, &rs->ctr_flags);
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND))) {
    			if (!rt_is_raid1(rt)) {
    				rs->ti->error = "max_write_behind option is only valid for RAID1";
    				return -EINVAL;
    			}
    
    			if (test_and_set_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags)) {
    				rs->ti->error = "Only one max_write_behind argument pair allowed";
    				return -EINVAL;
    			}
    
    			/*
    			 * In device-mapper, we specify things in sectors, but
    			 * MD records this value in kB
    			 */
    			value /= 2;
    			if (value > COUNTER_MAX) {
    				rs->ti->error = "Max write-behind limit out of range";
    				return -EINVAL;
    			}
    
    			rs->md.bitmap_info.max_write_behind = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP))) {
    			if (test_and_set_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags)) {
    				rs->ti->error = "Only one daemon_sleep argument pair allowed";
    				return -EINVAL;
    			}
    			if (!value || (value > MAX_SCHEDULE_TIMEOUT)) {
    				rs->ti->error = "daemon sleep period out of range";
    				return -EINVAL;
    			}
    			rs->md.bitmap_info.daemon_sleep = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET))) {
    			/* Userspace passes new data_offset after having extended the the data image LV */
    			if (test_and_set_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
    				rs->ti->error = "Only one data_offset argument pair allowed";
    				return -EINVAL;
    			}
    			/* Ensure sensible data offset */
    			if (value < 0 ||
    			    (value && (value < MIN_FREE_RESHAPE_SPACE || value % to_sector(PAGE_SIZE)))) {
    				rs->ti->error = "Bogus data_offset value";
    				return -EINVAL;
    			}
    			rs->data_offset = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS))) {
    			/* Define the +/-# of disks to add to/remove from the given raid set */
    			if (test_and_set_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
    				rs->ti->error = "Only one delta_disks argument pair allowed";
    				return -EINVAL;
    			}
    			/* Ensure MAX_RAID_DEVICES and raid type minimal_devs! */
    			if (!__within_range(abs(value), 1, MAX_RAID_DEVICES - rt->minimal_devs)) {
    				rs->ti->error = "Too many delta_disk requested";
    				return -EINVAL;
    			}
    
    			rs->delta_disks = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE))) {
    			if (test_and_set_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags)) {
    				rs->ti->error = "Only one stripe_cache argument pair allowed";
    				return -EINVAL;
    			}
    
    			if (!rt_is_raid456(rt)) {
    				rs->ti->error = "Inappropriate argument: stripe_cache";
    				return -EINVAL;
    			}
    
    			rs->stripe_cache_entries = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE))) {
    			if (test_and_set_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags)) {
    				rs->ti->error = "Only one min_recovery_rate argument pair allowed";
    				return -EINVAL;
    			}
    			if (value > INT_MAX) {
    				rs->ti->error = "min_recovery_rate out of range";
    				return -EINVAL;
    			}
    			rs->md.sync_speed_min = (int)value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE))) {
    			if (test_and_set_bit(__CTR_FLAG_MAX_RECOVERY_RATE, &rs->ctr_flags)) {
    				rs->ti->error = "Only one max_recovery_rate argument pair allowed";
    				return -EINVAL;
    			}
    			if (value > INT_MAX) {
    				rs->ti->error = "max_recovery_rate out of range";
    				return -EINVAL;
    			}
    			rs->md.sync_speed_max = (int)value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE))) {
    			if (test_and_set_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags)) {
    				rs->ti->error = "Only one region_size argument pair allowed";
    				return -EINVAL;
    			}
    
    			region_size = value;
    			rs->requested_bitmap_chunk_sectors = value;
    		} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES))) {
    			if (test_and_set_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags)) {
    				rs->ti->error = "Only one raid10_copies argument pair allowed";
    				return -EINVAL;
    			}
    
    			if (!__within_range(value, 2, rs->md.raid_disks)) {
    				rs->ti->error = "Bad value for 'raid10_copies'";
    				return -EINVAL;
    			}
    
    			raid10_copies = value;
    		} else {
    			DMERR("Unable to parse RAID parameter: %s", key);
    			rs->ti->error = "Unable to parse RAID parameter";
    			return -EINVAL;
    		}
    	}
    
    	if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) &&
    	    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
    		rs->ti->error = "sync and nosync are mutually exclusive";
    		return -EINVAL;
    	}
    
    	if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags) &&
    	    (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ||
    	     test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))) {
    		rs->ti->error = "sync/nosync and rebuild are mutually exclusive";
    		return -EINVAL;
    	}
    
    	if (write_mostly >= rs->md.raid_disks) {
    		rs->ti->error = "Can't set all raid1 devices to write_mostly";
    		return -EINVAL;
    	}
    
    	if (validate_region_size(rs, region_size))
    		return -EINVAL;
    
    	if (rs->md.chunk_sectors)
    		max_io_len = rs->md.chunk_sectors;
    	else
    		max_io_len = region_size;
    
    	if (dm_set_target_max_io_len(rs->ti, max_io_len))
    		return -EINVAL;
    
    	if (rt_is_raid10(rt)) {
    		if (raid10_copies > rs->md.raid_disks) {
    			rs->ti->error = "Not enough devices to satisfy specification";
    			return -EINVAL;
    		}
    
    		rs->md.new_layout = raid10_format_to_md_layout(rs, raid10_format, raid10_copies);
    		if (rs->md.new_layout < 0) {
    			rs->ti->error = "Error getting raid10 format";
    			return rs->md.new_layout;
    		}
    
    		rt = get_raid_type_by_ll(10, rs->md.new_layout);
    		if (!rt) {
    			rs->ti->error = "Failed to recognize new raid10 layout";
    			return -EINVAL;
    		}
    
    		if ((rt->algorithm == ALGORITHM_RAID10_DEFAULT ||
    		     rt->algorithm == ALGORITHM_RAID10_NEAR) &&
    		    test_bit(__CTR_FLAG_RAID10_USE_NEAR_SETS, &rs->ctr_flags)) {
    			rs->ti->error = "RAID10 format 'near' and 'raid10_use_near_sets' are incompatible";
    			return -EINVAL;
    		}
    	}
    
    	rs->raid10_copies = raid10_copies;
    
    	/* Assume there are no metadata devices until the drives are parsed */
    	rs->md.persistent = 0;
    	rs->md.external = 1;
    
    	/* Check, if any invalid ctr arguments have been passed in for the raid level */
    	return rs_check_for_valid_flags(rs);
    }
    
    /* Set raid4/5/6 cache size */
    static int rs_set_raid456_stripe_cache(struct raid_set *rs)
    {
    	int r;
    	struct r5conf *conf;
    	struct mddev *mddev = &rs->md;
    	uint32_t min_stripes = max(mddev->chunk_sectors, mddev->new_chunk_sectors) / 2;
    	uint32_t nr_stripes = rs->stripe_cache_entries;
    
    	if (!rt_is_raid456(rs->raid_type)) {
    		rs->ti->error = "Inappropriate raid level; cannot change stripe_cache size";
    		return -EINVAL;
    	}
    
    	if (nr_stripes < min_stripes) {
    		DMINFO("Adjusting requested %u stripe cache entries to %u to suit stripe size",
    		       nr_stripes, min_stripes);
    		nr_stripes = min_stripes;
    	}
    
    	conf = mddev->private;
    	if (!conf) {
    		rs->ti->error = "Cannot change stripe_cache size on inactive RAID set";
    		return -EINVAL;
    	}
    
    	/* Try setting number of stripes in raid456 stripe cache */
    	if (conf->min_nr_stripes != nr_stripes) {
    		r = raid5_set_cache_size(mddev, nr_stripes);
    		if (r) {
    			rs->ti->error = "Failed to set raid4/5/6 stripe cache size";
    			return r;
    		}
    
    		DMINFO("%u stripe cache entries", nr_stripes);
    	}
    
    	return 0;
    }
    
    /* Return # of data stripes as kept in mddev as of @rs (i.e. as of superblock) */
    static unsigned int mddev_data_stripes(struct raid_set *rs)
    {
    	return rs->md.raid_disks - rs->raid_type->parity_devs;
    }
    
    /* Return # of data stripes of @rs (i.e. as of ctr) */
    static unsigned int rs_data_stripes(struct raid_set *rs)
    {
    	return rs->raid_disks - rs->raid_type->parity_devs;
    }
    
    /*
     * Retrieve rdev->sectors from any valid raid device of @rs
     * to allow userpace to pass in arbitray "- -" device tupples.
     */
    static sector_t __rdev_sectors(struct raid_set *rs)
    {
    	int i;
    
    	for (i = 0; i < rs->md.raid_disks; i++) {
    		struct md_rdev *rdev = &rs->dev[i].rdev;
    
    		if (!test_bit(Journal, &rdev->flags) &&
    		    rdev->bdev && rdev->sectors)
    			return rdev->sectors;
    	}
    
    	return 0;
    }
    
    /* Check that calculated dev_sectors fits all component devices. */
    static int _check_data_dev_sectors(struct raid_set *rs)
    {
    	sector_t ds = ~0;
    	struct md_rdev *rdev;
    
    	rdev_for_each(rdev, &rs->md)
    		if (!test_bit(Journal, &rdev->flags) && rdev->bdev) {
    			ds = min(ds, to_sector(i_size_read(rdev->bdev->bd_inode)));
    			if (ds < rs->md.dev_sectors) {
    				rs->ti->error = "Component device(s) too small";
    				return -EINVAL;
    			}
    		}
    
    	return 0;
    }
    
    /* Calculate the sectors per device and per array used for @rs */
    static int rs_set_dev_and_array_sectors(struct raid_set *rs, bool use_mddev)
    {
    	int delta_disks;
    	unsigned int data_stripes;
    	struct mddev *mddev = &rs->md;
    	struct md_rdev *rdev;
    	sector_t array_sectors = rs->ti->len, dev_sectors = rs->ti->len;
    
    	if (use_mddev) {
    		delta_disks = mddev->delta_disks;
    		data_stripes = mddev_data_stripes(rs);
    	} else {
    		delta_disks = rs->delta_disks;
    		data_stripes = rs_data_stripes(rs);
    	}
    
    	/* Special raid1 case w/o delta_disks support (yet) */
    	if (rt_is_raid1(rs->raid_type))
    		;
    	else if (rt_is_raid10(rs->raid_type)) {
    		if (rs->raid10_copies < 2 ||
    		    delta_disks < 0) {
    			rs->ti->error = "Bogus raid10 data copies or delta disks";
    			return -EINVAL;
    		}
    
    		dev_sectors *= rs->raid10_copies;
    		if (sector_div(dev_sectors, data_stripes))
    			goto bad;
    
    		array_sectors = (data_stripes + delta_disks) * dev_sectors;
    		if (sector_div(array_sectors, rs->raid10_copies))
    			goto bad;
    
    	} else if (sector_div(dev_sectors, data_stripes))
    		goto bad;
    
    	else
    		/* Striped layouts */
    		array_sectors = (data_stripes + delta_disks) * dev_sectors;
    
    	rdev_for_each(rdev, mddev)
    		if (!test_bit(Journal, &rdev->flags))
    			rdev->sectors = dev_sectors;
    
    	mddev->array_sectors = array_sectors;
    	mddev->dev_sectors = dev_sectors;
    
    	return _check_data_dev_sectors(rs);
    bad:
    	rs->ti->error = "Target length not divisible by number of data devices";
    	return -EINVAL;
    }
    
    /* Setup recovery on @rs */
    static void __rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
    {
    	/* raid0 does not recover */
    	if (rs_is_raid0(rs))
    		rs->md.recovery_cp = MaxSector;
    	/*
    	 * A raid6 set has to be recovered either
    	 * completely or for the grown part to
    	 * ensure proper parity and Q-Syndrome
    	 */
    	else if (rs_is_raid6(rs))
    		rs->md.recovery_cp = dev_sectors;
    	/*
    	 * Other raid set types may skip recovery
    	 * depending on the 'nosync' flag.
    	 */
    	else
    		rs->md.recovery_cp = test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)
    				     ? MaxSector : dev_sectors;
    }
    
    /* Setup recovery on @rs based on raid type, device size and 'nosync' flag */
    static void rs_setup_recovery(struct raid_set *rs, sector_t dev_sectors)
    {
    	if (!dev_sectors)
    		/* New raid set or 'sync' flag provided */
    		__rs_setup_recovery(rs, 0);
    	else if (dev_sectors == MaxSector)
    		/* Prevent recovery */
    		__rs_setup_recovery(rs, MaxSector);
    	else if (__rdev_sectors(rs) < dev_sectors)
    		/* Grown raid set */
    		__rs_setup_recovery(rs, __rdev_sectors(rs));
    	else
    		__rs_setup_recovery(rs, MaxSector);
    }
    
    static void do_table_event(struct work_struct *ws)
    {
    	struct raid_set *rs = container_of(ws, struct raid_set, md.event_work);
    
    	smp_rmb(); /* Make sure we access most actual mddev properties */
    	if (!rs_is_reshaping(rs)) {
    		if (rs_is_raid10(rs))
    			rs_set_rdev_sectors(rs);
    		rs_set_capacity(rs);
    	}
    	dm_table_event(rs->ti->table);
    }
    
    static int raid_is_congested(struct dm_target_callbacks *cb, int bits)
    {
    	struct raid_set *rs = container_of(cb, struct raid_set, callbacks);
    
    	return mddev_congested(&rs->md, bits);
    }
    
    /*
     * Make sure a valid takover (level switch) is being requested on @rs
     *
     * Conversions of raid sets from one MD personality to another
     * have to conform to restrictions which are enforced here.
     */
    static int rs_check_takeover(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    	unsigned int near_copies;
    
    	if (rs->md.degraded) {
    		rs->ti->error = "Can't takeover degraded raid set";
    		return -EPERM;
    	}
    
    	if (rs_is_reshaping(rs)) {
    		rs->ti->error = "Can't takeover reshaping raid set";
    		return -EPERM;
    	}
    
    	switch (mddev->level) {
    	case 0:
    		/* raid0 -> raid1/5 with one disk */
    		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
    		    mddev->raid_disks == 1)
    			return 0;
    
    		/* raid0 -> raid10 */
    		if (mddev->new_level == 10 &&
    		    !(rs->raid_disks % mddev->raid_disks))
    			return 0;
    
    		/* raid0 with multiple disks -> raid4/5/6 */
    		if (__within_range(mddev->new_level, 4, 6) &&
    		    mddev->new_layout == ALGORITHM_PARITY_N &&
    		    mddev->raid_disks > 1)
    			return 0;
    
    		break;
    
    	case 10:
    		/* Can't takeover raid10_offset! */
    		if (__is_raid10_offset(mddev->layout))
    			break;
    
    		near_copies = __raid10_near_copies(mddev->layout);
    
    		/* raid10* -> raid0 */
    		if (mddev->new_level == 0) {
    			/* Can takeover raid10_near with raid disks divisable by data copies! */
    			if (near_copies > 1 &&
    			    !(mddev->raid_disks % near_copies)) {
    				mddev->raid_disks /= near_copies;
    				mddev->delta_disks = mddev->raid_disks;
    				return 0;
    			}
    
    			/* Can takeover raid10_far */
    			if (near_copies == 1 &&
    			    __raid10_far_copies(mddev->layout) > 1)
    				return 0;
    
    			break;
    		}
    
    		/* raid10_{near,far} -> raid1 */
    		if (mddev->new_level == 1 &&
    		    max(near_copies, __raid10_far_copies(mddev->layout)) == mddev->raid_disks)
    			return 0;
    
    		/* raid10_{near,far} with 2 disks -> raid4/5 */
    		if (__within_range(mddev->new_level, 4, 5) &&
    		    mddev->raid_disks == 2)
    			return 0;
    		break;
    
    	case 1:
    		/* raid1 with 2 disks -> raid4/5 */
    		if (__within_range(mddev->new_level, 4, 5) &&
    		    mddev->raid_disks == 2) {
    			mddev->degraded = 1;
    			return 0;
    		}
    
    		/* raid1 -> raid0 */
    		if (mddev->new_level == 0 &&
    		    mddev->raid_disks == 1)
    			return 0;
    
    		/* raid1 -> raid10 */
    		if (mddev->new_level == 10)
    			return 0;
    		break;
    
    	case 4:
    		/* raid4 -> raid0 */
    		if (mddev->new_level == 0)
    			return 0;
    
    		/* raid4 -> raid1/5 with 2 disks */
    		if ((mddev->new_level == 1 || mddev->new_level == 5) &&
    		    mddev->raid_disks == 2)
    			return 0;
    
    		/* raid4 -> raid5/6 with parity N */
    		if (__within_range(mddev->new_level, 5, 6) &&
    		    mddev->layout == ALGORITHM_PARITY_N)
    			return 0;
    		break;
    
    	case 5:
    		/* raid5 with parity N -> raid0 */
    		if (mddev->new_level == 0 &&
    		    mddev->layout == ALGORITHM_PARITY_N)
    			return 0;
    
    		/* raid5 with parity N -> raid4 */
    		if (mddev->new_level == 4 &&
    		    mddev->layout == ALGORITHM_PARITY_N)
    			return 0;
    
    		/* raid5 with 2 disks -> raid1/4/10 */
    		if ((mddev->new_level == 1 || mddev->new_level == 4 || mddev->new_level == 10) &&
    		    mddev->raid_disks == 2)
    			return 0;
    
    		/* raid5_* ->  raid6_*_6 with Q-Syndrome N (e.g. raid5_ra -> raid6_ra_6 */
    		if (mddev->new_level == 6 &&
    		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
    		      __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC_6, ALGORITHM_RIGHT_SYMMETRIC_6)))
    			return 0;
    		break;
    
    	case 6:
    		/* raid6 with parity N -> raid0 */
    		if (mddev->new_level == 0 &&
    		    mddev->layout == ALGORITHM_PARITY_N)
    			return 0;
    
    		/* raid6 with parity N -> raid4 */
    		if (mddev->new_level == 4 &&
    		    mddev->layout == ALGORITHM_PARITY_N)
    			return 0;
    
    		/* raid6_*_n with Q-Syndrome N -> raid5_* */
    		if (mddev->new_level == 5 &&
    		    ((mddev->layout == ALGORITHM_PARITY_N && mddev->new_layout == ALGORITHM_PARITY_N) ||
    		     __within_range(mddev->new_layout, ALGORITHM_LEFT_ASYMMETRIC, ALGORITHM_RIGHT_SYMMETRIC)))
    			return 0;
    
    	default:
    		break;
    	}
    
    	rs->ti->error = "takeover not possible";
    	return -EINVAL;
    }
    
    /* True if @rs requested to be taken over */
    static bool rs_takeover_requested(struct raid_set *rs)
    {
    	return rs->md.new_level != rs->md.level;
    }
    
    /* True if @rs is requested to reshape by ctr */
    static bool rs_reshape_requested(struct raid_set *rs)
    {
    	bool change;
    	struct mddev *mddev = &rs->md;
    
    	if (rs_takeover_requested(rs))
    		return false;
    
    	if (!mddev->level)
    		return false;
    
    	change = mddev->new_layout != mddev->layout ||
    		 mddev->new_chunk_sectors != mddev->chunk_sectors ||
    		 rs->delta_disks;
    
    	/* Historical case to support raid1 reshape without delta disks */
    	if (mddev->level == 1) {
    		if (rs->delta_disks)
    			return !!rs->delta_disks;
    
    		return !change &&
    		       mddev->raid_disks != rs->raid_disks;
    	}
    
    	if (mddev->level == 10)
    		return change &&
    		       !__is_raid10_far(mddev->new_layout) &&
    		       rs->delta_disks >= 0;
    
    	return change;
    }
    
    /*  Features */
    #define	FEATURE_FLAG_SUPPORTS_V190	0x1 /* Supports extended superblock */
    
    /* State flags for sb->flags */
    #define	SB_FLAG_RESHAPE_ACTIVE		0x1
    #define	SB_FLAG_RESHAPE_BACKWARDS	0x2
    
    /*
     * This structure is never routinely used by userspace, unlike md superblocks.
     * Devices with this superblock should only ever be accessed via device-mapper.
     */
    #define DM_RAID_MAGIC 0x64526D44
    struct dm_raid_superblock {
    	__le32 magic;		/* "DmRd" */
    	__le32 compat_features;	/* Used to indicate compatible features (like 1.9.0 ondisk metadata extension) */
    
    	__le32 num_devices;	/* Number of devices in this raid set. (Max 64) */
    	__le32 array_position;	/* The position of this drive in the raid set */
    
    	__le64 events;		/* Incremented by md when superblock updated */
    	__le64 failed_devices;	/* Pre 1.9.0 part of bit field of devices to */
    				/* indicate failures (see extension below) */
    
    	/*
    	 * This offset tracks the progress of the repair or replacement of
    	 * an individual drive.
    	 */
    	__le64 disk_recovery_offset;
    
    	/*
    	 * This offset tracks the progress of the initial raid set
    	 * synchronisation/parity calculation.
    	 */
    	__le64 array_resync_offset;
    
    	/*
    	 * raid characteristics
    	 */
    	__le32 level;
    	__le32 layout;
    	__le32 stripe_sectors;
    
    	/********************************************************************
    	 * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
    	 *
    	 * FEATURE_FLAG_SUPPORTS_V190 in the compat_features member indicates that those exist
    	 */
    
    	__le32 flags; /* Flags defining array states for reshaping */
    
    	/*
    	 * This offset tracks the progress of a raid
    	 * set reshape in order to be able to restart it
    	 */
    	__le64 reshape_position;
    
    	/*
    	 * These define the properties of the array in case of an interrupted reshape
    	 */
    	__le32 new_level;
    	__le32 new_layout;
    	__le32 new_stripe_sectors;
    	__le32 delta_disks;
    
    	__le64 array_sectors; /* Array size in sectors */
    
    	/*
    	 * Sector offsets to data on devices (reshaping).
    	 * Needed to support out of place reshaping, thus
    	 * not writing over any stripes whilst converting
    	 * them from old to new layout
    	 */
    	__le64 data_offset;
    	__le64 new_data_offset;
    
    	__le64 sectors; /* Used device size in sectors */
    
    	/*
    	 * Additonal Bit field of devices indicating failures to support
    	 * up to 256 devices with the 1.9.0 on-disk metadata format
    	 */
    	__le64 extended_failed_devices[DISKS_ARRAY_ELEMS - 1];
    
    	__le32 incompat_features;	/* Used to indicate any incompatible features */
    
    	/* Always set rest up to logical block size to 0 when writing (see get_metadata_device() below). */
    } __packed;
    
    /*
     * Check for reshape constraints on raid set @rs:
     *
     * - reshape function non-existent
     * - degraded set
     * - ongoing recovery
     * - ongoing reshape
     *
     * Returns 0 if none or -EPERM if given constraint
     * and error message reference in @errmsg
     */
    static int rs_check_reshape(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    
    	if (!mddev->pers || !mddev->pers->check_reshape)
    		rs->ti->error = "Reshape not supported";
    	else if (mddev->degraded)
    		rs->ti->error = "Can't reshape degraded raid set";
    	else if (rs_is_recovering(rs))
    		rs->ti->error = "Convert request on recovering raid set prohibited";
    	else if (rs_is_reshaping(rs))
    		rs->ti->error = "raid set already reshaping!";
    	else if (!(rs_is_raid1(rs) || rs_is_raid10(rs) || rs_is_raid456(rs)))
    		rs->ti->error = "Reshaping only supported for raid1/4/5/6/10";
    	else
    		return 0;
    
    	return -EPERM;
    }
    
    static int read_disk_sb(struct md_rdev *rdev, int size, bool force_reload)
    {
    	BUG_ON(!rdev->sb_page);
    
    	if (rdev->sb_loaded && !force_reload)
    		return 0;
    
    	rdev->sb_loaded = 0;
    
    	if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, 0, true)) {
    		DMERR("Failed to read superblock of device at position %d",
    		      rdev->raid_disk);
    		md_error(rdev->mddev, rdev);
    		set_bit(Faulty, &rdev->flags);
    		return -EIO;
    	}
    
    	rdev->sb_loaded = 1;
    
    	return 0;
    }
    
    static void sb_retrieve_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
    {
    	failed_devices[0] = le64_to_cpu(sb->failed_devices);
    	memset(failed_devices + 1, 0, sizeof(sb->extended_failed_devices));
    
    	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
    		int i = ARRAY_SIZE(sb->extended_failed_devices);
    
    		while (i--)
    			failed_devices[i+1] = le64_to_cpu(sb->extended_failed_devices[i]);
    	}
    }
    
    static void sb_update_failed_devices(struct dm_raid_superblock *sb, uint64_t *failed_devices)
    {
    	int i = ARRAY_SIZE(sb->extended_failed_devices);
    
    	sb->failed_devices = cpu_to_le64(failed_devices[0]);
    	while (i--)
    		sb->extended_failed_devices[i] = cpu_to_le64(failed_devices[i+1]);
    }
    
    /*
     * Synchronize the superblock members with the raid set properties
     *
     * All superblock data is little endian.
     */
    static void super_sync(struct mddev *mddev, struct md_rdev *rdev)
    {
    	bool update_failed_devices = false;
    	unsigned int i;
    	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
    	struct dm_raid_superblock *sb;
    	struct raid_set *rs = container_of(mddev, struct raid_set, md);
    
    	/* No metadata device, no superblock */
    	if (!rdev->meta_bdev)
    		return;
    
    	BUG_ON(!rdev->sb_page);
    
    	sb = page_address(rdev->sb_page);
    
    	sb_retrieve_failed_devices(sb, failed_devices);
    
    	for (i = 0; i < rs->raid_disks; i++)
    		if (!rs->dev[i].data_dev || test_bit(Faulty, &rs->dev[i].rdev.flags)) {
    			update_failed_devices = true;
    			set_bit(i, (void *) failed_devices);
    		}
    
    	if (update_failed_devices)
    		sb_update_failed_devices(sb, failed_devices);
    
    	sb->magic = cpu_to_le32(DM_RAID_MAGIC);
    	sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
    
    	sb->num_devices = cpu_to_le32(mddev->raid_disks);
    	sb->array_position = cpu_to_le32(rdev->raid_disk);
    
    	sb->events = cpu_to_le64(mddev->events);
    
    	sb->disk_recovery_offset = cpu_to_le64(rdev->recovery_offset);
    	sb->array_resync_offset = cpu_to_le64(mddev->recovery_cp);
    
    	sb->level = cpu_to_le32(mddev->level);
    	sb->layout = cpu_to_le32(mddev->layout);
    	sb->stripe_sectors = cpu_to_le32(mddev->chunk_sectors);
    
    	/********************************************************************
    	 * BELOW FOLLOW V1.9.0 EXTENSIONS TO THE PRISTINE SUPERBLOCK FORMAT!!!
    	 *
    	 * FEATURE_FLAG_SUPPORTS_V190 in the compat_features member indicates that those exist
    	 */
    	sb->new_level = cpu_to_le32(mddev->new_level);
    	sb->new_layout = cpu_to_le32(mddev->new_layout);
    	sb->new_stripe_sectors = cpu_to_le32(mddev->new_chunk_sectors);
    
    	sb->delta_disks = cpu_to_le32(mddev->delta_disks);
    
    	smp_rmb(); /* Make sure we access most recent reshape position */
    	sb->reshape_position = cpu_to_le64(mddev->reshape_position);
    	if (le64_to_cpu(sb->reshape_position) != MaxSector) {
    		/* Flag ongoing reshape */
    		sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE);
    
    		if (mddev->delta_disks < 0 || mddev->reshape_backwards)
    			sb->flags |= cpu_to_le32(SB_FLAG_RESHAPE_BACKWARDS);
    	} else {
    		/* Clear reshape flags */
    		sb->flags &= ~(cpu_to_le32(SB_FLAG_RESHAPE_ACTIVE|SB_FLAG_RESHAPE_BACKWARDS));
    	}
    
    	sb->array_sectors = cpu_to_le64(mddev->array_sectors);
    	sb->data_offset = cpu_to_le64(rdev->data_offset);
    	sb->new_data_offset = cpu_to_le64(rdev->new_data_offset);
    	sb->sectors = cpu_to_le64(rdev->sectors);
    	sb->incompat_features = cpu_to_le32(0);
    
    	/* Zero out the rest of the payload after the size of the superblock */
    	memset(sb + 1, 0, rdev->sb_size - sizeof(*sb));
    }
    
    /*
     * super_load
     *
     * This function creates a superblock if one is not found on the device
     * and will decide which superblock to use if there's a choice.
     *
     * Return: 1 if use rdev, 0 if use refdev, -Exxx otherwise
     */
    static int super_load(struct md_rdev *rdev, struct md_rdev *refdev)
    {
    	int r;
    	struct dm_raid_superblock *sb;
    	struct dm_raid_superblock *refsb;
    	uint64_t events_sb, events_refsb;
    
    	r = read_disk_sb(rdev, rdev->sb_size, false);
    	if (r)
    		return r;
    
    	sb = page_address(rdev->sb_page);
    
    	/*
    	 * Two cases that we want to write new superblocks and rebuild:
    	 * 1) New device (no matching magic number)
    	 * 2) Device specified for rebuild (!In_sync w/ offset == 0)
    	 */
    	if ((sb->magic != cpu_to_le32(DM_RAID_MAGIC)) ||
    	    (!test_bit(In_sync, &rdev->flags) && !rdev->recovery_offset)) {
    		super_sync(rdev->mddev, rdev);
    
    		set_bit(FirstUse, &rdev->flags);
    		sb->compat_features = cpu_to_le32(FEATURE_FLAG_SUPPORTS_V190);
    
    		/* Force writing of superblocks to disk */
    		set_bit(MD_SB_CHANGE_DEVS, &rdev->mddev->sb_flags);
    
    		/* Any superblock is better than none, choose that if given */
    		return refdev ? 0 : 1;
    	}
    
    	if (!refdev)
    		return 1;
    
    	events_sb = le64_to_cpu(sb->events);
    
    	refsb = page_address(refdev->sb_page);
    	events_refsb = le64_to_cpu(refsb->events);
    
    	return (events_sb > events_refsb) ? 1 : 0;
    }
    
    static int super_init_validation(struct raid_set *rs, struct md_rdev *rdev)
    {
    	int role;
    	unsigned int d;
    	struct mddev *mddev = &rs->md;
    	uint64_t events_sb;
    	uint64_t failed_devices[DISKS_ARRAY_ELEMS];
    	struct dm_raid_superblock *sb;
    	uint32_t new_devs = 0, rebuild_and_new = 0, rebuilds = 0;
    	struct md_rdev *r;
    	struct dm_raid_superblock *sb2;
    
    	sb = page_address(rdev->sb_page);
    	events_sb = le64_to_cpu(sb->events);
    
    	/*
    	 * Initialise to 1 if this is a new superblock.
    	 */
    	mddev->events = events_sb ? : 1;
    
    	mddev->reshape_position = MaxSector;
    
    	mddev->raid_disks = le32_to_cpu(sb->num_devices);
    	mddev->level = le32_to_cpu(sb->level);
    	mddev->layout = le32_to_cpu(sb->layout);
    	mddev->chunk_sectors = le32_to_cpu(sb->stripe_sectors);
    
    	/*
    	 * Reshaping is supported, e.g. reshape_position is valid
    	 * in superblock and superblock content is authoritative.
    	 */
    	if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190) {
    		/* Superblock is authoritative wrt given raid set layout! */
    		mddev->new_level = le32_to_cpu(sb->new_level);
    		mddev->new_layout = le32_to_cpu(sb->new_layout);
    		mddev->new_chunk_sectors = le32_to_cpu(sb->new_stripe_sectors);
    		mddev->delta_disks = le32_to_cpu(sb->delta_disks);
    		mddev->array_sectors = le64_to_cpu(sb->array_sectors);
    
    		/* raid was reshaping and got interrupted */
    		if (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_ACTIVE) {
    			if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags)) {
    				DMERR("Reshape requested but raid set is still reshaping");
    				return -EINVAL;
    			}
    
    			if (mddev->delta_disks < 0 ||
    			    (!mddev->delta_disks && (le32_to_cpu(sb->flags) & SB_FLAG_RESHAPE_BACKWARDS)))
    				mddev->reshape_backwards = 1;
    			else
    				mddev->reshape_backwards = 0;
    
    			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
    			rs->raid_type = get_raid_type_by_ll(mddev->level, mddev->layout);
    		}
    
    	} else {
    		/*
    		 * No takeover/reshaping, because we don't have the extended v1.9.0 metadata
    		 */
    		struct raid_type *rt_cur = get_raid_type_by_ll(mddev->level, mddev->layout);
    		struct raid_type *rt_new = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
    
    		if (rs_takeover_requested(rs)) {
    			if (rt_cur && rt_new)
    				DMERR("Takeover raid sets from %s to %s not yet supported by metadata. (raid level change)",
    				      rt_cur->name, rt_new->name);
    			else
    				DMERR("Takeover raid sets not yet supported by metadata. (raid level change)");
    			return -EINVAL;
    		} else if (rs_reshape_requested(rs)) {
    			DMERR("Reshaping raid sets not yet supported by metadata. (raid layout change keeping level)");
    			if (mddev->layout != mddev->new_layout) {
    				if (rt_cur && rt_new)
    					DMERR("	 current layout %s vs new layout %s",
    					      rt_cur->name, rt_new->name);
    				else
    					DMERR("	 current layout 0x%X vs new layout 0x%X",
    					      le32_to_cpu(sb->layout), mddev->new_layout);
    			}
    			if (mddev->chunk_sectors != mddev->new_chunk_sectors)
    				DMERR("	 current stripe sectors %u vs new stripe sectors %u",
    				      mddev->chunk_sectors, mddev->new_chunk_sectors);
    			if (rs->delta_disks)
    				DMERR("	 current %u disks vs new %u disks",
    				      mddev->raid_disks, mddev->raid_disks + rs->delta_disks);
    			if (rs_is_raid10(rs)) {
    				DMERR("	 Old layout: %s w/ %u copies",
    				      raid10_md_layout_to_format(mddev->layout),
    				      raid10_md_layout_to_copies(mddev->layout));
    				DMERR("	 New layout: %s w/ %u copies",
    				      raid10_md_layout_to_format(mddev->new_layout),
    				      raid10_md_layout_to_copies(mddev->new_layout));
    			}
    			return -EINVAL;
    		}
    
    		DMINFO("Discovered old metadata format; upgrading to extended metadata format");
    	}
    
    	if (!test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
    		mddev->recovery_cp = le64_to_cpu(sb->array_resync_offset);
    
    	/*
    	 * During load, we set FirstUse if a new superblock was written.
    	 * There are two reasons we might not have a superblock:
    	 * 1) The raid set is brand new - in which case, all of the
    	 *    devices must have their In_sync bit set.	Also,
    	 *    recovery_cp must be 0, unless forced.
    	 * 2) This is a new device being added to an old raid set
    	 *    and the new device needs to be rebuilt - in which
    	 *    case the In_sync bit will /not/ be set and
    	 *    recovery_cp must be MaxSector.
    	 * 3) This is/are a new device(s) being added to an old
    	 *    raid set during takeover to a higher raid level
    	 *    to provide capacity for redundancy or during reshape
    	 *    to add capacity to grow the raid set.
    	 */
    	d = 0;
    	rdev_for_each(r, mddev) {
    		if (test_bit(Journal, &rdev->flags))
    			continue;
    
    		if (test_bit(FirstUse, &r->flags))
    			new_devs++;
    
    		if (!test_bit(In_sync, &r->flags)) {
    			DMINFO("Device %d specified for rebuild; clearing superblock",
    				r->raid_disk);
    			rebuilds++;
    
    			if (test_bit(FirstUse, &r->flags))
    				rebuild_and_new++;
    		}
    
    		d++;
    	}
    
    	if (new_devs == rs->raid_disks || !rebuilds) {
    		/* Replace a broken device */
    		if (new_devs == 1 && !rs->delta_disks)
    			;
    		if (new_devs == rs->raid_disks) {
    			DMINFO("Superblocks created for new raid set");
    			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
    		} else if (new_devs != rebuilds &&
    			   new_devs != rs->delta_disks) {
    			DMERR("New device injected into existing raid set without "
    			      "'delta_disks' or 'rebuild' parameter specified");
    			return -EINVAL;
    		}
    	} else if (new_devs && new_devs != rebuilds) {
    		DMERR("%u 'rebuild' devices cannot be injected into"
    		      " a raid set with %u other first-time devices",
    		      rebuilds, new_devs);
    		return -EINVAL;
    	} else if (rebuilds) {
    		if (rebuild_and_new && rebuilds != rebuild_and_new) {
    			DMERR("new device%s provided without 'rebuild'",
    			      new_devs > 1 ? "s" : "");
    			return -EINVAL;
    		} else if (rs_is_recovering(rs)) {
    			DMERR("'rebuild' specified while raid set is not in-sync (recovery_cp=%llu)",
    			      (unsigned long long) mddev->recovery_cp);
    			return -EINVAL;
    		} else if (rs_is_reshaping(rs)) {
    			DMERR("'rebuild' specified while raid set is being reshaped (reshape_position=%llu)",
    			      (unsigned long long) mddev->reshape_position);
    			return -EINVAL;
    		}
    	}
    
    	/*
    	 * Now we set the Faulty bit for those devices that are
    	 * recorded in the superblock as failed.
    	 */
    	sb_retrieve_failed_devices(sb, failed_devices);
    	rdev_for_each(r, mddev) {
    		if (test_bit(Journal, &rdev->flags) ||
    		    !r->sb_page)
    			continue;
    		sb2 = page_address(r->sb_page);
    		sb2->failed_devices = 0;
    		memset(sb2->extended_failed_devices, 0, sizeof(sb2->extended_failed_devices));
    
    		/*
    		 * Check for any device re-ordering.
    		 */
    		if (!test_bit(FirstUse, &r->flags) && (r->raid_disk >= 0)) {
    			role = le32_to_cpu(sb2->array_position);
    			if (role < 0)
    				continue;
    
    			if (role != r->raid_disk) {
    				if (rs_is_raid10(rs) && __is_raid10_near(mddev->layout)) {
    					if (mddev->raid_disks % __raid10_near_copies(mddev->layout) ||
    					    rs->raid_disks % rs->raid10_copies) {
    						rs->ti->error =
    							"Cannot change raid10 near set to odd # of devices!";
    						return -EINVAL;
    					}
    
    					sb2->array_position = cpu_to_le32(r->raid_disk);
    
    				} else if (!(rs_is_raid10(rs) && rt_is_raid0(rs->raid_type)) &&
    					   !(rs_is_raid0(rs) && rt_is_raid10(rs->raid_type)) &&
    					   !rt_is_raid1(rs->raid_type)) {
    					rs->ti->error = "Cannot change device positions in raid set";
    					return -EINVAL;
    				}
    
    				DMINFO("raid device #%d now at position #%d", role, r->raid_disk);
    			}
    
    			/*
    			 * Partial recovery is performed on
    			 * returning failed devices.
    			 */
    			if (test_bit(role, (void *) failed_devices))
    				set_bit(Faulty, &r->flags);
    		}
    	}
    
    	return 0;
    }
    
    static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
    {
    	struct mddev *mddev = &rs->md;
    	struct dm_raid_superblock *sb;
    
    	if (rs_is_raid0(rs) || !rdev->sb_page || rdev->raid_disk < 0)
    		return 0;
    
    	sb = page_address(rdev->sb_page);
    
    	/*
    	 * If mddev->events is not set, we know we have not yet initialized
    	 * the array.
    	 */
    	if (!mddev->events && super_init_validation(rs, rdev))
    		return -EINVAL;
    
    	if (le32_to_cpu(sb->compat_features) &&
    	    le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190) {
    		rs->ti->error = "Unable to assemble array: Unknown flag(s) in compatible feature flags";
    		return -EINVAL;
    	}
    
    	if (sb->incompat_features) {
    		rs->ti->error = "Unable to assemble array: No incompatible feature flags supported yet";
    		return -EINVAL;
    	}
    
    	/* Enable bitmap creation for RAID levels != 0 */
    	mddev->bitmap_info.offset = rt_is_raid0(rs->raid_type) ? 0 : to_sector(4096);
    	mddev->bitmap_info.default_offset = mddev->bitmap_info.offset;
    
    	if (!test_and_clear_bit(FirstUse, &rdev->flags)) {
    		/*
    		 * Retrieve rdev size stored in superblock to be prepared for shrink.
    		 * Check extended superblock members are present otherwise the size
    		 * will not be set!
    		 */
    		if (le32_to_cpu(sb->compat_features) & FEATURE_FLAG_SUPPORTS_V190)
    			rdev->sectors = le64_to_cpu(sb->sectors);
    
    		rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
    		if (rdev->recovery_offset == MaxSector)
    			set_bit(In_sync, &rdev->flags);
    		/*
    		 * If no reshape in progress -> we're recovering single
    		 * disk(s) and have to set the device(s) to out-of-sync
    		 */
    		else if (!rs_is_reshaping(rs))
    			clear_bit(In_sync, &rdev->flags); /* Mandatory for recovery */
    	}
    
    	/*
    	 * If a device comes back, set it as not In_sync and no longer faulty.
    	 */
    	if (test_and_clear_bit(Faulty, &rdev->flags)) {
    		rdev->recovery_offset = 0;
    		clear_bit(In_sync, &rdev->flags);
    		rdev->saved_raid_disk = rdev->raid_disk;
    	}
    
    	/* Reshape support -> restore repective data offsets */
    	rdev->data_offset = le64_to_cpu(sb->data_offset);
    	rdev->new_data_offset = le64_to_cpu(sb->new_data_offset);
    
    	return 0;
    }
    
    /*
     * Analyse superblocks and select the freshest.
     */
    static int analyse_superblocks(struct dm_target *ti, struct raid_set *rs)
    {
    	int r;
    	struct md_rdev *rdev, *freshest;
    	struct mddev *mddev = &rs->md;
    
    	freshest = NULL;
    	rdev_for_each(rdev, mddev) {
    		if (test_bit(Journal, &rdev->flags))
    			continue;
    
    		if (!rdev->meta_bdev)
    			continue;
    
    		/* Set superblock offset/size for metadata device. */
    		rdev->sb_start = 0;
    		rdev->sb_size = bdev_logical_block_size(rdev->meta_bdev);
    		if (rdev->sb_size < sizeof(struct dm_raid_superblock) || rdev->sb_size > PAGE_SIZE) {
    			DMERR("superblock size of a logical block is no longer valid");
    			return -EINVAL;
    		}
    
    		/*
    		 * Skipping super_load due to CTR_FLAG_SYNC will cause
    		 * the array to undergo initialization again as
    		 * though it were new.	This is the intended effect
    		 * of the "sync" directive.
    		 *
    		 * With reshaping capability added, we must ensure that
    		 * that the "sync" directive is disallowed during the reshape.
    		 */
    		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
    			continue;
    
    		r = super_load(rdev, freshest);
    
    		switch (r) {
    		case 1:
    			freshest = rdev;
    			break;
    		case 0:
    			break;
    		default:
    			/* This is a failure to read the superblock from the metadata device. */
    			/*
    			 * We have to keep any raid0 data/metadata device pairs or
    			 * the MD raid0 personality will fail to start the array.
    			 */
    			if (rs_is_raid0(rs))
    				continue;
    
    			/*
    			 * We keep the dm_devs to be able to emit the device tuple
    			 * properly on the table line in raid_status() (rather than
    			 * mistakenly acting as if '- -' got passed into the constructor).
    			 *
    			 * The rdev has to stay on the same_set list to allow for
    			 * the attempt to restore faulty devices on second resume.
    			 */
    			rdev->raid_disk = rdev->saved_raid_disk = -1;
    			break;
    		}
    	}
    
    	if (!freshest)
    		return 0;
    
    	/*
    	 * Validation of the freshest device provides the source of
    	 * validation for the remaining devices.
    	 */
    	rs->ti->error = "Unable to assemble array: Invalid superblocks";
    	if (super_validate(rs, freshest))
    		return -EINVAL;
    
    	if (validate_raid_redundancy(rs)) {
    		rs->ti->error = "Insufficient redundancy to activate array";
    		return -EINVAL;
    	}
    
    	rdev_for_each(rdev, mddev)
    		if (!test_bit(Journal, &rdev->flags) &&
    		    rdev != freshest &&
    		    super_validate(rs, rdev))
    			return -EINVAL;
    	return 0;
    }
    
    /*
     * Adjust data_offset and new_data_offset on all disk members of @rs
     * for out of place reshaping if requested by contructor
     *
     * We need free space at the beginning of each raid disk for forward
     * and at the end for backward reshapes which userspace has to provide
     * via remapping/reordering of space.
     */
    static int rs_adjust_data_offsets(struct raid_set *rs)
    {
    	sector_t data_offset = 0, new_data_offset = 0;
    	struct md_rdev *rdev;
    
    	/* Constructor did not request data offset change */
    	if (!test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags)) {
    		if (!rs_is_reshapable(rs))
    			goto out;
    
    		return 0;
    	}
    
    	/* HM FIXME: get InSync raid_dev? */
    	rdev = &rs->dev[0].rdev;
    
    	if (rs->delta_disks < 0) {
    		/*
    		 * Removing disks (reshaping backwards):
    		 *
    		 * - before reshape: data is at offset 0 and free space
    		 *		     is at end of each component LV
    		 *
    		 * - after reshape: data is at offset rs->data_offset != 0 on each component LV
    		 */
    		data_offset = 0;
    		new_data_offset = rs->data_offset;
    
    	} else if (rs->delta_disks > 0) {
    		/*
    		 * Adding disks (reshaping forwards):
    		 *
    		 * - before reshape: data is at offset rs->data_offset != 0 and
    		 *		     free space is at begin of each component LV
    		 *
    		 * - after reshape: data is at offset 0 on each component LV
    		 */
    		data_offset = rs->data_offset;
    		new_data_offset = 0;
    
    	} else {
    		/*
    		 * User space passes in 0 for data offset after having removed reshape space
    		 *
    		 * - or - (data offset != 0)
    		 *
    		 * Changing RAID layout or chunk size -> toggle offsets
    		 *
    		 * - before reshape: data is at offset rs->data_offset 0 and
    		 *		     free space is at end of each component LV
    		 *		     -or-
    		 *                   data is at offset rs->data_offset != 0 and
    		 *		     free space is at begin of each component LV
    		 *
    		 * - after reshape: data is at offset 0 if it was at offset != 0
    		 *                  or at offset != 0 if it was at offset 0
    		 *                  on each component LV
    		 *
    		 */
    		data_offset = rs->data_offset ? rdev->data_offset : 0;
    		new_data_offset = data_offset ? 0 : rs->data_offset;
    		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    	}
    
    	/*
    	 * Make sure we got a minimum amount of free sectors per device
    	 */
    	if (rs->data_offset &&
    	    to_sector(i_size_read(rdev->bdev->bd_inode)) - rs->md.dev_sectors < MIN_FREE_RESHAPE_SPACE) {
    		rs->ti->error = data_offset ? "No space for forward reshape" :
    					      "No space for backward reshape";
    		return -ENOSPC;
    	}
    out:
    	/*
    	 * Raise recovery_cp in case data_offset != 0 to
    	 * avoid false recovery positives in the constructor.
    	 */
    	if (rs->md.recovery_cp < rs->md.dev_sectors)
    		rs->md.recovery_cp += rs->dev[0].rdev.data_offset;
    
    	/* Adjust data offsets on all rdevs but on any raid4/5/6 journal device */
    	rdev_for_each(rdev, &rs->md) {
    		if (!test_bit(Journal, &rdev->flags)) {
    			rdev->data_offset = data_offset;
    			rdev->new_data_offset = new_data_offset;
    		}
    	}
    
    	return 0;
    }
    
    /* Userpace reordered disks -> adjust raid_disk indexes in @rs */
    static void __reorder_raid_disk_indexes(struct raid_set *rs)
    {
    	int i = 0;
    	struct md_rdev *rdev;
    
    	rdev_for_each(rdev, &rs->md) {
    		if (!test_bit(Journal, &rdev->flags)) {
    			rdev->raid_disk = i++;
    			rdev->saved_raid_disk = rdev->new_raid_disk = -1;
    		}
    	}
    }
    
    /*
     * Setup @rs for takeover by a different raid level
     */
    static int rs_setup_takeover(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    	struct md_rdev *rdev;
    	unsigned int d = mddev->raid_disks = rs->raid_disks;
    	sector_t new_data_offset = rs->dev[0].rdev.data_offset ? 0 : rs->data_offset;
    
    	if (rt_is_raid10(rs->raid_type)) {
    		if (mddev->level == 0) {
    			/* Userpace reordered disks -> adjust raid_disk indexes */
    			__reorder_raid_disk_indexes(rs);
    
    			/* raid0 -> raid10_far layout */
    			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_FAR,
    								   rs->raid10_copies);
    		} else if (mddev->level == 1)
    			/* raid1 -> raid10_near layout */
    			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
    								   rs->raid_disks);
    		else
    			return -EINVAL;
    
    	}
    
    	clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
    	mddev->recovery_cp = MaxSector;
    
    	while (d--) {
    		rdev = &rs->dev[d].rdev;
    
    		if (test_bit(d, (void *) rs->rebuild_disks)) {
    			clear_bit(In_sync, &rdev->flags);
    			clear_bit(Faulty, &rdev->flags);
    			mddev->recovery_cp = rdev->recovery_offset = 0;
    			/* Bitmap has to be created when we do an "up" takeover */
    			set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
    		}
    
    		rdev->new_data_offset = new_data_offset;
    	}
    
    	return 0;
    }
    
    /* Prepare @rs for reshape */
    static int rs_prepare_reshape(struct raid_set *rs)
    {
    	bool reshape;
    	struct mddev *mddev = &rs->md;
    
    	if (rs_is_raid10(rs)) {
    		if (rs->raid_disks != mddev->raid_disks &&
    		    __is_raid10_near(mddev->layout) &&
    		    rs->raid10_copies &&
    		    rs->raid10_copies != __raid10_near_copies(mddev->layout)) {
    			/*
    			 * raid disk have to be multiple of data copies to allow this conversion,
    			 *
    			 * This is actually not a reshape it is a
    			 * rebuild of any additional mirrors per group
    			 */
    			if (rs->raid_disks % rs->raid10_copies) {
    				rs->ti->error = "Can't reshape raid10 mirror groups";
    				return -EINVAL;
    			}
    
    			/* Userpace reordered disks to add/remove mirrors -> adjust raid_disk indexes */
    			__reorder_raid_disk_indexes(rs);
    			mddev->layout = raid10_format_to_md_layout(rs, ALGORITHM_RAID10_NEAR,
    								   rs->raid10_copies);
    			mddev->new_layout = mddev->layout;
    			reshape = false;
    		} else
    			reshape = true;
    
    	} else if (rs_is_raid456(rs))
    		reshape = true;
    
    	else if (rs_is_raid1(rs)) {
    		if (rs->delta_disks) {
    			/* Process raid1 via delta_disks */
    			mddev->degraded = rs->delta_disks < 0 ? -rs->delta_disks : rs->delta_disks;
    			reshape = true;
    		} else {
    			/* Process raid1 without delta_disks */
    			mddev->raid_disks = rs->raid_disks;
    			reshape = false;
    		}
    	} else {
    		rs->ti->error = "Called with bogus raid type";
    		return -EINVAL;
    	}
    
    	if (reshape) {
    		set_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags);
    		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    	} else if (mddev->raid_disks < rs->raid_disks)
    		/* Create new superblocks and bitmaps, if any new disks */
    		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    
    	return 0;
    }
    
    /* Get reshape sectors from data_offsets or raid set */
    static sector_t _get_reshape_sectors(struct raid_set *rs)
    {
    	struct md_rdev *rdev;
    	sector_t reshape_sectors = 0;
    
    	rdev_for_each(rdev, &rs->md)
    		if (!test_bit(Journal, &rdev->flags)) {
    			reshape_sectors = (rdev->data_offset > rdev->new_data_offset) ?
    					rdev->data_offset - rdev->new_data_offset :
    					rdev->new_data_offset - rdev->data_offset;
    			break;
    		}
    
    	return max(reshape_sectors, (sector_t) rs->data_offset);
    }
    
    /*
     *
     * - change raid layout
     * - change chunk size
     * - add disks
     * - remove disks
     */
    static int rs_setup_reshape(struct raid_set *rs)
    {
    	int r = 0;
    	unsigned int cur_raid_devs, d;
    	sector_t reshape_sectors = _get_reshape_sectors(rs);
    	struct mddev *mddev = &rs->md;
    	struct md_rdev *rdev;
    
    	mddev->delta_disks = rs->delta_disks;
    	cur_raid_devs = mddev->raid_disks;
    
    	/* Ignore impossible layout change whilst adding/removing disks */
    	if (mddev->delta_disks &&
    	    mddev->layout != mddev->new_layout) {
    		DMINFO("Ignoring invalid layout change with delta_disks=%d", rs->delta_disks);
    		mddev->new_layout = mddev->layout;
    	}
    
    	/*
    	 * Adjust array size:
    	 *
    	 * - in case of adding disk(s), array size has
    	 *   to grow after the disk adding reshape,
    	 *   which'll hapen in the event handler;
    	 *   reshape will happen forward, so space has to
    	 *   be available at the beginning of each disk
    	 *
    	 * - in case of removing disk(s), array size
    	 *   has to shrink before starting the reshape,
    	 *   which'll happen here;
    	 *   reshape will happen backward, so space has to
    	 *   be available at the end of each disk
    	 *
    	 * - data_offset and new_data_offset are
    	 *   adjusted for aforementioned out of place
    	 *   reshaping based on userspace passing in
    	 *   the "data_offset <sectors>" key/value
    	 *   pair via the constructor
    	 */
    
    	/* Add disk(s) */
    	if (rs->delta_disks > 0) {
    		/* Prepare disks for check in raid4/5/6/10 {check|start}_reshape */
    		for (d = cur_raid_devs; d < rs->raid_disks; d++) {
    			rdev = &rs->dev[d].rdev;
    			clear_bit(In_sync, &rdev->flags);
    
    			/*
    			 * save_raid_disk needs to be -1, or recovery_offset will be set to 0
    			 * by md, which'll store that erroneously in the superblock on reshape
    			 */
    			rdev->saved_raid_disk = -1;
    			rdev->raid_disk = d;
    
    			rdev->sectors = mddev->dev_sectors;
    			rdev->recovery_offset = rs_is_raid1(rs) ? 0 : MaxSector;
    		}
    
    		mddev->reshape_backwards = 0; /* adding disk(s) -> forward reshape */
    
    	/* Remove disk(s) */
    	} else if (rs->delta_disks < 0) {
    		r = rs_set_dev_and_array_sectors(rs, true);
    		mddev->reshape_backwards = 1; /* removing disk(s) -> backward reshape */
    
    	/* Change layout and/or chunk size */
    	} else {
    		/*
    		 * Reshape layout (e.g. raid5_ls -> raid5_n) and/or chunk size:
    		 *
    		 * keeping number of disks and do layout change ->
    		 *
    		 * toggle reshape_backward depending on data_offset:
    		 *
    		 * - free space upfront -> reshape forward
    		 *
    		 * - free space at the end -> reshape backward
    		 *
    		 *
    		 * This utilizes free reshape space avoiding the need
    		 * for userspace to move (parts of) LV segments in
    		 * case of layout/chunksize change  (for disk
    		 * adding/removing reshape space has to be at
    		 * the proper address (see above with delta_disks):
    		 *
    		 * add disk(s)   -> begin
    		 * remove disk(s)-> end
    		 */
    		mddev->reshape_backwards = rs->dev[0].rdev.data_offset ? 0 : 1;
    	}
    
    	/*
    	 * Adjust device size for forward reshape
    	 * because md_finish_reshape() reduces it.
    	 */
    	if (!mddev->reshape_backwards)
    		rdev_for_each(rdev, &rs->md)
    			if (!test_bit(Journal, &rdev->flags))
    				rdev->sectors += reshape_sectors;
    
    	return r;
    }
    
    /*
     * Enable/disable discard support on RAID set depending on
     * RAID level and discard properties of underlying RAID members.
     */
    static void configure_discard_support(struct raid_set *rs)
    {
    	int i;
    	bool raid456;
    	struct dm_target *ti = rs->ti;
    
    	/*
    	 * XXX: RAID level 4,5,6 require zeroing for safety.
    	 */
    	raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6);
    
    	for (i = 0; i < rs->raid_disks; i++) {
    		struct request_queue *q;
    
    		if (!rs->dev[i].rdev.bdev)
    			continue;
    
    		q = bdev_get_queue(rs->dev[i].rdev.bdev);
    		if (!q || !blk_queue_discard(q))
    			return;
    
    		if (raid456) {
    			if (!devices_handle_discard_safely) {
    				DMERR("raid456 discard support disabled due to discard_zeroes_data uncertainty.");
    				DMERR("Set dm-raid.devices_handle_discard_safely=Y to override.");
    				return;
    			}
    		}
    	}
    
    	/*
    	 * RAID1 and RAID10 personalities require bio splitting,
    	 * RAID0/4/5/6 don't and process large discard bios properly.
    	 */
    	ti->split_discard_bios = !!(rs->md.level == 1 || rs->md.level == 10);
    	ti->num_discard_bios = 1;
    }
    
    /*
     * Construct a RAID0/1/10/4/5/6 mapping:
     * Args:
     *	<raid_type> <#raid_params> <raid_params>{0,}	\
     *	<#raid_devs> [<meta_dev1> <dev1>]{1,}
     *
     * <raid_params> varies by <raid_type>.	 See 'parse_raid_params' for
     * details on possible <raid_params>.
     *
     * Userspace is free to initialize the metadata devices, hence the superblocks to
     * enforce recreation based on the passed in table parameters.
     *
     */
    static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
    {
    	int r;
    	bool resize = false;
    	struct raid_type *rt;
    	unsigned int num_raid_params, num_raid_devs;
    	sector_t calculated_dev_sectors, rdev_sectors, reshape_sectors;
    	struct raid_set *rs = NULL;
    	const char *arg;
    	struct rs_layout rs_layout;
    	struct dm_arg_set as = { argc, argv }, as_nrd;
    	struct dm_arg _args[] = {
    		{ 0, as.argc, "Cannot understand number of raid parameters" },
    		{ 1, 254, "Cannot understand number of raid devices parameters" }
    	};
    
    	/* Must have <raid_type> */
    	arg = dm_shift_arg(&as);
    	if (!arg) {
    		ti->error = "No arguments";
    		return -EINVAL;
    	}
    
    	rt = get_raid_type(arg);
    	if (!rt) {
    		ti->error = "Unrecognised raid_type";
    		return -EINVAL;
    	}
    
    	/* Must have <#raid_params> */
    	if (dm_read_arg_group(_args, &as, &num_raid_params, &ti->error))
    		return -EINVAL;
    
    	/* number of raid device tupples <meta_dev data_dev> */
    	as_nrd = as;
    	dm_consume_args(&as_nrd, num_raid_params);
    	_args[1].max = (as_nrd.argc - 1) / 2;
    	if (dm_read_arg(_args + 1, &as_nrd, &num_raid_devs, &ti->error))
    		return -EINVAL;
    
    	if (!__within_range(num_raid_devs, 1, MAX_RAID_DEVICES)) {
    		ti->error = "Invalid number of supplied raid devices";
    		return -EINVAL;
    	}
    
    	rs = raid_set_alloc(ti, rt, num_raid_devs);
    	if (IS_ERR(rs))
    		return PTR_ERR(rs);
    
    	r = parse_raid_params(rs, &as, num_raid_params);
    	if (r)
    		goto bad;
    
    	r = parse_dev_params(rs, &as);
    	if (r)
    		goto bad;
    
    	rs->md.sync_super = super_sync;
    
    	/*
    	 * Calculate ctr requested array and device sizes to allow
    	 * for superblock analysis needing device sizes defined.
    	 *
    	 * Any existing superblock will overwrite the array and device sizes
    	 */
    	r = rs_set_dev_and_array_sectors(rs, false);
    	if (r)
    		goto bad;
    
    	calculated_dev_sectors = rs->md.dev_sectors;
    
    	/*
    	 * Backup any new raid set level, layout, ...
    	 * requested to be able to compare to superblock
    	 * members for conversion decisions.
    	 */
    	rs_config_backup(rs, &rs_layout);
    
    	r = analyse_superblocks(ti, rs);
    	if (r)
    		goto bad;
    
    	rdev_sectors = __rdev_sectors(rs);
    	if (!rdev_sectors) {
    		ti->error = "Invalid rdev size";
    		r = -EINVAL;
    		goto bad;
    	}
    
    
    	reshape_sectors = _get_reshape_sectors(rs);
    	if (calculated_dev_sectors != rdev_sectors)
    		resize = calculated_dev_sectors != (reshape_sectors ? rdev_sectors - reshape_sectors : rdev_sectors);
    
    	INIT_WORK(&rs->md.event_work, do_table_event);
    	ti->private = rs;
    	ti->num_flush_bios = 1;
    
    	/* Restore any requested new layout for conversion decision */
    	rs_config_restore(rs, &rs_layout);
    
    	/*
    	 * Now that we have any superblock metadata available,
    	 * check for new, recovering, reshaping, to be taken over,
    	 * to be reshaped or an existing, unchanged raid set to
    	 * run in sequence.
    	 */
    	if (test_bit(MD_ARRAY_FIRST_USE, &rs->md.flags)) {
    		/* A new raid6 set has to be recovered to ensure proper parity and Q-Syndrome */
    		if (rs_is_raid6(rs) &&
    		    test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags)) {
    			ti->error = "'nosync' not allowed for new raid6 set";
    			r = -EINVAL;
    			goto bad;
    		}
    		rs_setup_recovery(rs, 0);
    		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    		rs_set_new(rs);
    	} else if (rs_is_recovering(rs)) {
    		/* A recovering raid set may be resized */
    		; /* skip setup rs */
    	} else if (rs_is_reshaping(rs)) {
    		/* Have to reject size change request during reshape */
    		if (resize) {
    			ti->error = "Can't resize a reshaping raid set";
    			r = -EPERM;
    			goto bad;
    		}
    		/* skip setup rs */
    	} else if (rs_takeover_requested(rs)) {
    		if (rs_is_reshaping(rs)) {
    			ti->error = "Can't takeover a reshaping raid set";
    			r = -EPERM;
    			goto bad;
    		}
    
    		/* We can't takeover a journaled raid4/5/6 */
    		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
    			ti->error = "Can't takeover a journaled raid4/5/6 set";
    			r = -EPERM;
    			goto bad;
    		}
    
    		/*
    		 * If a takeover is needed, userspace sets any additional
    		 * devices to rebuild and we can check for a valid request here.
    		 *
    		 * If acceptible, set the level to the new requested
    		 * one, prohibit requesting recovery, allow the raid
    		 * set to run and store superblocks during resume.
    		 */
    		r = rs_check_takeover(rs);
    		if (r)
    			goto bad;
    
    		r = rs_setup_takeover(rs);
    		if (r)
    			goto bad;
    
    		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    		/* Takeover ain't recovery, so disable recovery */
    		rs_setup_recovery(rs, MaxSector);
    		rs_set_new(rs);
    	} else if (rs_reshape_requested(rs)) {
    		/*
    		 * No need to check for 'ongoing' takeover here, because takeover
    		 * is an instant operation as oposed to an ongoing reshape.
    		 */
    
    		/* We can't reshape a journaled raid4/5/6 */
    		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags)) {
    			ti->error = "Can't reshape a journaled raid4/5/6 set";
    			r = -EPERM;
    			goto bad;
    		}
    
    		/*
    		  * We can only prepare for a reshape here, because the
    		  * raid set needs to run to provide the repective reshape
    		  * check functions via its MD personality instance.
    		  *
    		  * So do the reshape check after md_run() succeeded.
    		  */
    		r = rs_prepare_reshape(rs);
    		if (r)
    			return r;
    
    		/* Reshaping ain't recovery, so disable recovery */
    		rs_setup_recovery(rs, MaxSector);
    		rs_set_cur(rs);
    	} else {
    		/* May not set recovery when a device rebuild is requested */
    		if (test_bit(__CTR_FLAG_REBUILD, &rs->ctr_flags)) {
    			rs_setup_recovery(rs, MaxSector);
    			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);
    		} else
    			rs_setup_recovery(rs, test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags) ?
    					      0 : (resize ? calculated_dev_sectors : MaxSector));
    		rs_set_cur(rs);
    	}
    
    	/* If constructor requested it, change data and new_data offsets */
    	r = rs_adjust_data_offsets(rs);
    	if (r)
    		goto bad;
    
    	/* Start raid set read-only and assumed clean to change in raid_resume() */
    	rs->md.ro = 1;
    	rs->md.in_sync = 1;
    	set_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
    
    	/* Has to be held on running the array */
    	mddev_lock_nointr(&rs->md);
    	r = md_run(&rs->md);
    	rs->md.in_sync = 0; /* Assume already marked dirty */
    	if (r) {
    		ti->error = "Failed to run raid array";
    		mddev_unlock(&rs->md);
    		goto bad;
    	}
    
    	rs->callbacks.congested_fn = raid_is_congested;
    	dm_table_add_target_callbacks(ti->table, &rs->callbacks);
    
    	/* If raid4/5/6 journal mode explictely requested (only possible with journal dev) -> set it */
    	if (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags)) {
    		r = r5c_journal_mode_set(&rs->md, rs->journal_dev.mode);
    		if (r) {
    			ti->error = "Failed to set raid4/5/6 journal mode";
    			mddev_unlock(&rs->md);
    			goto bad_journal_mode_set;
    		}
    	}
    
    	mddev_suspend(&rs->md);
    	set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
    
    	/* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
    	if (rs_is_raid456(rs)) {
    		r = rs_set_raid456_stripe_cache(rs);
    		if (r)
    			goto bad_stripe_cache;
    	}
    
    	/* Now do an early reshape check */
    	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
    		r = rs_check_reshape(rs);
    		if (r)
    			goto bad_check_reshape;
    
    		/* Restore new, ctr requested layout to perform check */
    		rs_config_restore(rs, &rs_layout);
    
    		if (rs->md.pers->start_reshape) {
    			r = rs->md.pers->check_reshape(&rs->md);
    			if (r) {
    				ti->error = "Reshape check failed";
    				goto bad_check_reshape;
    			}
    		}
    	}
    
    	/* Disable/enable discard support on raid set. */
    	configure_discard_support(rs);
    
    	mddev_unlock(&rs->md);
    	return 0;
    
    bad_journal_mode_set:
    bad_stripe_cache:
    bad_check_reshape:
    	md_stop(&rs->md);
    bad:
    	raid_set_free(rs);
    
    	return r;
    }
    
    static void raid_dtr(struct dm_target *ti)
    {
    	struct raid_set *rs = ti->private;
    
    	list_del_init(&rs->callbacks.list);
    	md_stop(&rs->md);
    	raid_set_free(rs);
    }
    
    static int raid_map(struct dm_target *ti, struct bio *bio)
    {
    	struct raid_set *rs = ti->private;
    	struct mddev *mddev = &rs->md;
    
    	/*
    	 * If we're reshaping to add disk(s)), ti->len and
    	 * mddev->array_sectors will differ during the process
    	 * (ti->len > mddev->array_sectors), so we have to requeue
    	 * bios with addresses > mddev->array_sectors here or
    	 * there will occur accesses past EOD of the component
    	 * data images thus erroring the raid set.
    	 */
    	if (unlikely(bio_end_sector(bio) > mddev->array_sectors))
    		return DM_MAPIO_REQUEUE;
    
    	md_handle_request(mddev, bio);
    
    	return DM_MAPIO_SUBMITTED;
    }
    
    /* Return string describing the current sync action of @mddev */
    static const char *decipher_sync_action(struct mddev *mddev, unsigned long recovery)
    {
    	if (test_bit(MD_RECOVERY_FROZEN, &recovery))
    		return "frozen";
    
    	if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
    	    (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
    		if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
    			return "reshape";
    
    		if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
    			if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
    				return "resync";
    			else if (test_bit(MD_RECOVERY_CHECK, &recovery))
    				return "check";
    			return "repair";
    		}
    
    		if (test_bit(MD_RECOVERY_RECOVER, &recovery))
    			return "recover";
    	}
    
    	return "idle";
    }
    
    /*
     * Return status string for @rdev
     *
     * Status characters:
     *
     *  'D' = Dead/Failed raid set component or raid4/5/6 journal device
     *  'a' = Alive but not in-sync raid set component _or_ alive raid4/5/6 'write_back' journal device
     *  'A' = Alive and in-sync raid set component _or_ alive raid4/5/6 'write_through' journal device
     *  '-' = Non-existing device (i.e. uspace passed '- -' into the ctr)
     */
    static const char *__raid_dev_status(struct raid_set *rs, struct md_rdev *rdev, bool array_in_sync)
    {
    	if (!rdev->bdev)
    		return "-";
    	else if (test_bit(Faulty, &rdev->flags))
    		return "D";
    	else if (test_bit(Journal, &rdev->flags))
    		return (rs->journal_dev.mode == R5C_JOURNAL_MODE_WRITE_THROUGH) ? "A" : "a";
    	else if (!array_in_sync || !test_bit(In_sync, &rdev->flags))
    		return "a";
    	else
    		return "A";
    }
    
    /* Helper to return resync/reshape progress for @rs and @array_in_sync */
    static sector_t rs_get_progress(struct raid_set *rs, unsigned long recovery,
    				sector_t resync_max_sectors, bool *array_in_sync)
    {
    	sector_t r, curr_resync_completed;
    	struct mddev *mddev = &rs->md;
    
    	curr_resync_completed = mddev->curr_resync_completed ?: mddev->recovery_cp;
    	*array_in_sync = false;
    
    	if (rs_is_raid0(rs)) {
    		r = resync_max_sectors;
    		*array_in_sync = true;
    
    	} else {
    		r = mddev->reshape_position;
    
    		/* Reshape is relative to the array size */
    		if (test_bit(MD_RECOVERY_RESHAPE, &recovery) ||
    		    r != MaxSector) {
    			if (r == MaxSector) {
    				*array_in_sync = true;
    				r = resync_max_sectors;
    			} else {
    				/* Got to reverse on backward reshape */
    				if (mddev->reshape_backwards)
    					r = mddev->array_sectors - r;
    
    				/* Devide by # of data stripes */
    				sector_div(r, mddev_data_stripes(rs));
    			}
    
    		/* Sync is relative to the component device size */
    		} else if (test_bit(MD_RECOVERY_RUNNING, &recovery))
    			r = curr_resync_completed;
    		else
    			r = mddev->recovery_cp;
    
    		if ((r == MaxSector) ||
    		    (test_bit(MD_RECOVERY_DONE, &recovery) &&
    		     (mddev->curr_resync_completed == resync_max_sectors))) {
    			/*
    			 * Sync complete.
    			 */
    			*array_in_sync = true;
    			r = resync_max_sectors;
    		} else if (test_bit(MD_RECOVERY_REQUESTED, &recovery)) {
    			/*
    			 * If "check" or "repair" is occurring, the raid set has
    			 * undergone an initial sync and the health characters
    			 * should not be 'a' anymore.
    			 */
    			*array_in_sync = true;
    		} else {
    			struct md_rdev *rdev;
    
    			/*
    			 * The raid set may be doing an initial sync, or it may
    			 * be rebuilding individual components.	 If all the
    			 * devices are In_sync, then it is the raid set that is
    			 * being initialized.
    			 */
    			rdev_for_each(rdev, mddev)
    				if (!test_bit(Journal, &rdev->flags) &&
    				    !test_bit(In_sync, &rdev->flags))
    					*array_in_sync = true;
    #if 0
    			r = 0; /* HM FIXME: TESTME: https://bugzilla.redhat.com/show_bug.cgi?id=1210637 ? */
    #endif
    		}
    	}
    
    	return r;
    }
    
    /* Helper to return @dev name or "-" if !@dev */
    static const char *__get_dev_name(struct dm_dev *dev)
    {
    	return dev ? dev->name : "-";
    }
    
    static void raid_status(struct dm_target *ti, status_type_t type,
    			unsigned int status_flags, char *result, unsigned int maxlen)
    {
    	struct raid_set *rs = ti->private;
    	struct mddev *mddev = &rs->md;
    	struct r5conf *conf = mddev->private;
    	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
    	bool array_in_sync;
    	unsigned long recovery;
    	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */
    	unsigned int sz = 0;
    	unsigned int rebuild_disks;
    	unsigned int write_mostly_params = 0;
    	sector_t progress, resync_max_sectors, resync_mismatches;
    	const char *sync_action;
    	struct raid_type *rt;
    
    	switch (type) {
    	case STATUSTYPE_INFO:
    		/* *Should* always succeed */
    		rt = get_raid_type_by_ll(mddev->new_level, mddev->new_layout);
    		if (!rt)
    			return;
    
    		DMEMIT("%s %d ", rt->name, mddev->raid_disks);
    
    		/* Access most recent mddev properties for status output */
    		smp_rmb();
    		recovery = rs->md.recovery;
    		/* Get sensible max sectors even if raid set not yet started */
    		resync_max_sectors = test_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags) ?
    				      mddev->resync_max_sectors : mddev->dev_sectors;
    		progress = rs_get_progress(rs, recovery, resync_max_sectors, &array_in_sync);
    		resync_mismatches = (mddev->last_sync_action && !strcasecmp(mddev->last_sync_action, "check")) ?
    				    atomic64_read(&mddev->resync_mismatches) : 0;
    		sync_action = decipher_sync_action(&rs->md, recovery);
    
    		/* HM FIXME: do we want another state char for raid0? It shows 'D'/'A'/'-' now */
    		for (i = 0; i < rs->raid_disks; i++)
    			DMEMIT(__raid_dev_status(rs, &rs->dev[i].rdev, array_in_sync));
    
    		/*
    		 * In-sync/Reshape ratio:
    		 *  The in-sync ratio shows the progress of:
    		 *   - Initializing the raid set
    		 *   - Rebuilding a subset of devices of the raid set
    		 *  The user can distinguish between the two by referring
    		 *  to the status characters.
    		 *
    		 *  The reshape ratio shows the progress of
    		 *  changing the raid layout or the number of
    		 *  disks of a raid set
    		 */
    		DMEMIT(" %llu/%llu", (unsigned long long) progress,
    				     (unsigned long long) resync_max_sectors);
    
    		/*
    		 * v1.5.0+:
    		 *
    		 * Sync action:
    		 *   See Documentation/device-mapper/dm-raid.txt for
    		 *   information on each of these states.
    		 */
    		DMEMIT(" %s", sync_action);
    
    		/*
    		 * v1.5.0+:
    		 *
    		 * resync_mismatches/mismatch_cnt
    		 *   This field shows the number of discrepancies found when
    		 *   performing a "check" of the raid set.
    		 */
    		DMEMIT(" %llu", (unsigned long long) resync_mismatches);
    
    		/*
    		 * v1.9.0+:
    		 *
    		 * data_offset (needed for out of space reshaping)
    		 *   This field shows the data offset into the data
    		 *   image LV where the first stripes data starts.
    		 *
    		 * We keep data_offset equal on all raid disks of the set,
    		 * so retrieving it from the first raid disk is sufficient.
    		 */
    		DMEMIT(" %llu", (unsigned long long) rs->dev[0].rdev.data_offset);
    
    		/*
    		 * v1.10.0+:
    		 */
    		DMEMIT(" %s", test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags) ?
    			      __raid_dev_status(rs, &rs->journal_dev.rdev, 0) : "-");
    		break;
    
    	case STATUSTYPE_TABLE:
    		/* Report the table line string you would use to construct this raid set */
    
    		/* Calculate raid parameter count */
    		for (i = 0; i < rs->raid_disks; i++)
    			if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
    				write_mostly_params += 2;
    		rebuild_disks = memweight(rs->rebuild_disks, DISKS_ARRAY_ELEMS * sizeof(*rs->rebuild_disks));
    		raid_param_cnt += rebuild_disks * 2 +
    				  write_mostly_params +
    				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_NO_ARGS) +
    				  hweight32(rs->ctr_flags & CTR_FLAG_OPTIONS_ONE_ARG) * 2 +
    				  (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags) ? 2 : 0) +
    				  (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags) ? 2 : 0);
    
    		/* Emit table line */
    		/* This has to be in the documented order for userspace! */
    		DMEMIT("%s %u %u", rs->raid_type->name, raid_param_cnt, mddev->new_chunk_sectors);
    		if (test_bit(__CTR_FLAG_SYNC, &rs->ctr_flags))
    			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_SYNC));
    		if (test_bit(__CTR_FLAG_NOSYNC, &rs->ctr_flags))
    			DMEMIT(" %s", dm_raid_arg_name_by_flag(CTR_FLAG_NOSYNC));
    		if (rebuild_disks)
    			for (i = 0; i < rs->raid_disks; i++)
    				if (test_bit(rs->dev[i].rdev.raid_disk, (void *) rs->rebuild_disks))
    					DMEMIT(" %s %u", dm_raid_arg_name_by_flag(CTR_FLAG_REBUILD),
    							 rs->dev[i].rdev.raid_disk);
    		if (test_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags))
    			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP),
    					  mddev->bitmap_info.daemon_sleep);
    		if (test_bit(__CTR_FLAG_MIN_RECOVERY_RATE, &rs->ctr_flags))
    			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MIN_RECOVERY_RATE),
    					 mddev->sync_speed_min);
    		if (test_bit(__CTR_FLAG_MAX_RECOVERY_RATE, &rs->ctr_flags))
    			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_RECOVERY_RATE),
    					 mddev->sync_speed_max);
    		if (write_mostly_params)
    			for (i = 0; i < rs->raid_disks; i++)
    				if (test_bit(WriteMostly, &rs->dev[i].rdev.flags))
    					DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_WRITE_MOSTLY),
    					       rs->dev[i].rdev.raid_disk);
    		if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
    			DMEMIT(" %s %lu", dm_raid_arg_name_by_flag(CTR_FLAG_MAX_WRITE_BEHIND),
    					  mddev->bitmap_info.max_write_behind);
    		if (test_bit(__CTR_FLAG_STRIPE_CACHE, &rs->ctr_flags))
    			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_STRIPE_CACHE),
    					 max_nr_stripes);
    		if (test_bit(__CTR_FLAG_REGION_SIZE, &rs->ctr_flags))
    			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_REGION_SIZE),
    					   (unsigned long long) to_sector(mddev->bitmap_info.chunksize));
    		if (test_bit(__CTR_FLAG_RAID10_COPIES, &rs->ctr_flags))
    			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_COPIES),
    					 raid10_md_layout_to_copies(mddev->layout));
    		if (test_bit(__CTR_FLAG_RAID10_FORMAT, &rs->ctr_flags))
    			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_RAID10_FORMAT),
    					 raid10_md_layout_to_format(mddev->layout));
    		if (test_bit(__CTR_FLAG_DELTA_DISKS, &rs->ctr_flags))
    			DMEMIT(" %s %d", dm_raid_arg_name_by_flag(CTR_FLAG_DELTA_DISKS),
    					 max(rs->delta_disks, mddev->delta_disks));
    		if (test_bit(__CTR_FLAG_DATA_OFFSET, &rs->ctr_flags))
    			DMEMIT(" %s %llu", dm_raid_arg_name_by_flag(CTR_FLAG_DATA_OFFSET),
    					   (unsigned long long) rs->data_offset);
    		if (test_bit(__CTR_FLAG_JOURNAL_DEV, &rs->ctr_flags))
    			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_DEV),
    					__get_dev_name(rs->journal_dev.dev));
    		if (test_bit(__CTR_FLAG_JOURNAL_MODE, &rs->ctr_flags))
    			DMEMIT(" %s %s", dm_raid_arg_name_by_flag(CTR_FLAG_JOURNAL_MODE),
    					 md_journal_mode_to_dm_raid(rs->journal_dev.mode));
    		DMEMIT(" %d", rs->raid_disks);
    		for (i = 0; i < rs->raid_disks; i++)
    			DMEMIT(" %s %s", __get_dev_name(rs->dev[i].meta_dev),
    					 __get_dev_name(rs->dev[i].data_dev));
    	}
    }
    
    static int raid_message(struct dm_target *ti, unsigned int argc, char **argv)
    {
    	struct raid_set *rs = ti->private;
    	struct mddev *mddev = &rs->md;
    
    	if (!mddev->pers || !mddev->pers->sync_request)
    		return -EINVAL;
    
    	if (!strcasecmp(argv[0], "frozen"))
    		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    	else
    		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    
    	if (!strcasecmp(argv[0], "idle") || !strcasecmp(argv[0], "frozen")) {
    		if (mddev->sync_thread) {
    			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
    			md_reap_sync_thread(mddev);
    		}
    	} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
    		   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
    		return -EBUSY;
    	else if (!strcasecmp(argv[0], "resync"))
    		; /* MD_RECOVERY_NEEDED set below */
    	else if (!strcasecmp(argv[0], "recover"))
    		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
    	else {
    		if (!strcasecmp(argv[0], "check")) {
    			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
    			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
    			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
    		} else if (!strcasecmp(argv[0], "repair")) {
    			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
    			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
    		} else
    			return -EINVAL;
    	}
    	if (mddev->ro == 2) {
    		/* A write to sync_action is enough to justify
    		 * canceling read-auto mode
    		 */
    		mddev->ro = 0;
    		if (!mddev->suspended && mddev->sync_thread)
    			md_wakeup_thread(mddev->sync_thread);
    	}
    	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
    	if (!mddev->suspended && mddev->thread)
    		md_wakeup_thread(mddev->thread);
    
    	return 0;
    }
    
    static int raid_iterate_devices(struct dm_target *ti,
    				iterate_devices_callout_fn fn, void *data)
    {
    	struct raid_set *rs = ti->private;
    	unsigned int i;
    	int r = 0;
    
    	for (i = 0; !r && i < rs->md.raid_disks; i++)
    		if (rs->dev[i].data_dev)
    			r = fn(ti,
    				 rs->dev[i].data_dev,
    				 0, /* No offset on data devs */
    				 rs->md.dev_sectors,
    				 data);
    
    	return r;
    }
    
    static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
    {
    	struct raid_set *rs = ti->private;
    	unsigned int chunk_size = to_bytes(rs->md.chunk_sectors);
    
    	blk_limits_io_min(limits, chunk_size);
    	blk_limits_io_opt(limits, chunk_size * mddev_data_stripes(rs));
    }
    
    static void raid_postsuspend(struct dm_target *ti)
    {
    	struct raid_set *rs = ti->private;
    
    	if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
    		/* Writes have to be stopped before suspending to avoid deadlocks. */
    		if (!test_bit(MD_RECOVERY_FROZEN, &rs->md.recovery))
    			md_stop_writes(&rs->md);
    
    		mddev_lock_nointr(&rs->md);
    		mddev_suspend(&rs->md);
    		mddev_unlock(&rs->md);
    	}
    }
    
    static void attempt_restore_of_faulty_devices(struct raid_set *rs)
    {
    	int i;
    	uint64_t cleared_failed_devices[DISKS_ARRAY_ELEMS];
    	unsigned long flags;
    	bool cleared = false;
    	struct dm_raid_superblock *sb;
    	struct mddev *mddev = &rs->md;
    	struct md_rdev *r;
    
    	/* RAID personalities have to provide hot add/remove methods or we need to bail out. */
    	if (!mddev->pers || !mddev->pers->hot_add_disk || !mddev->pers->hot_remove_disk)
    		return;
    
    	memset(cleared_failed_devices, 0, sizeof(cleared_failed_devices));
    
    	for (i = 0; i < mddev->raid_disks; i++) {
    		r = &rs->dev[i].rdev;
    		/* HM FIXME: enhance journal device recovery processing */
    		if (test_bit(Journal, &r->flags))
    			continue;
    
    		if (test_bit(Faulty, &r->flags) &&
    		    r->meta_bdev && !read_disk_sb(r, r->sb_size, true)) {
    			DMINFO("Faulty %s device #%d has readable super block."
    			       "  Attempting to revive it.",
    			       rs->raid_type->name, i);
    
    			/*
    			 * Faulty bit may be set, but sometimes the array can
    			 * be suspended before the personalities can respond
    			 * by removing the device from the array (i.e. calling
    			 * 'hot_remove_disk').	If they haven't yet removed
    			 * the failed device, its 'raid_disk' number will be
    			 * '>= 0' - meaning we must call this function
    			 * ourselves.
    			 */
    			flags = r->flags;
    			clear_bit(In_sync, &r->flags); /* Mandatory for hot remove. */
    			if (r->raid_disk >= 0) {
    				if (mddev->pers->hot_remove_disk(mddev, r)) {
    					/* Failed to revive this device, try next */
    					r->flags = flags;
    					continue;
    				}
    			} else
    				r->raid_disk = r->saved_raid_disk = i;
    
    			clear_bit(Faulty, &r->flags);
    			clear_bit(WriteErrorSeen, &r->flags);
    
    			if (mddev->pers->hot_add_disk(mddev, r)) {
    				/* Failed to revive this device, try next */
    				r->raid_disk = r->saved_raid_disk = -1;
    				r->flags = flags;
    			} else {
    				clear_bit(In_sync, &r->flags);
    				r->recovery_offset = 0;
    				set_bit(i, (void *) cleared_failed_devices);
    				cleared = true;
    			}
    		}
    	}
    
    	/* If any failed devices could be cleared, update all sbs failed_devices bits */
    	if (cleared) {
    		uint64_t failed_devices[DISKS_ARRAY_ELEMS];
    
    		rdev_for_each(r, &rs->md) {
    			if (test_bit(Journal, &r->flags))
    				continue;
    
    			sb = page_address(r->sb_page);
    			sb_retrieve_failed_devices(sb, failed_devices);
    
    			for (i = 0; i < DISKS_ARRAY_ELEMS; i++)
    				failed_devices[i] &= ~cleared_failed_devices[i];
    
    			sb_update_failed_devices(sb, failed_devices);
    		}
    	}
    }
    
    static int __load_dirty_region_bitmap(struct raid_set *rs)
    {
    	int r = 0;
    
    	/* Try loading the bitmap unless "raid0", which does not have one */
    	if (!rs_is_raid0(rs) &&
    	    !test_and_set_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags)) {
    		r = bitmap_load(&rs->md);
    		if (r)
    			DMERR("Failed to load bitmap");
    	}
    
    	return r;
    }
    
    /* Enforce updating all superblocks */
    static void rs_update_sbs(struct raid_set *rs)
    {
    	struct mddev *mddev = &rs->md;
    	int ro = mddev->ro;
    
    	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
    	mddev->ro = 0;
    	md_update_sb(mddev, 1);
    	mddev->ro = ro;
    }
    
    /*
     * Reshape changes raid algorithm of @rs to new one within personality
     * (e.g. raid6_zr -> raid6_nc), changes stripe size, adds/removes
     * disks from a raid set thus growing/shrinking it or resizes the set
     *
     * Call mddev_lock_nointr() before!
     */
    static int rs_start_reshape(struct raid_set *rs)
    {
    	int r;
    	struct mddev *mddev = &rs->md;
    	struct md_personality *pers = mddev->pers;
    
    	r = rs_setup_reshape(rs);
    	if (r)
    		return r;
    
    	/* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */
    	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
    		mddev_resume(mddev);
    
    	/*
    	 * Check any reshape constraints enforced by the personalility
    	 *
    	 * May as well already kick the reshape off so that * pers->start_reshape() becomes optional.
    	 */
    	r = pers->check_reshape(mddev);
    	if (r) {
    		rs->ti->error = "pers->check_reshape() failed";
    		return r;
    	}
    
    	/*
    	 * Personality may not provide start reshape method in which
    	 * case check_reshape above has already covered everything
    	 */
    	if (pers->start_reshape) {
    		r = pers->start_reshape(mddev);
    		if (r) {
    			rs->ti->error = "pers->start_reshape() failed";
    			return r;
    		}
    	}
    
    	/* Suspend because a resume will happen in raid_resume() */
    	set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
    	mddev_suspend(mddev);
    
    	/*
    	 * Now reshape got set up, update superblocks to
    	 * reflect the fact so that a table reload will
    	 * access proper superblock content in the ctr.
    	 */
    	rs_update_sbs(rs);
    
    	return 0;
    }
    
    static int raid_preresume(struct dm_target *ti)
    {
    	int r;
    	struct raid_set *rs = ti->private;
    	struct mddev *mddev = &rs->md;
    
    	/* This is a resume after a suspend of the set -> it's already started */
    	if (test_and_set_bit(RT_FLAG_RS_PRERESUMED, &rs->runtime_flags))
    		return 0;
    
    	/*
    	 * The superblocks need to be updated on disk if the
    	 * array is new or new devices got added (thus zeroed
    	 * out by userspace) or __load_dirty_region_bitmap
    	 * will overwrite them in core with old data or fail.
    	 */
    	if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))
    		rs_update_sbs(rs);
    
    	/* Load the bitmap from disk unless raid0 */
    	r = __load_dirty_region_bitmap(rs);
    	if (r)
    		return r;
    
    	/* Resize bitmap to adjust to changed region size (aka MD bitmap chunksize) */
    	if (test_bit(RT_FLAG_RS_BITMAP_LOADED, &rs->runtime_flags) && mddev->bitmap &&
    	    mddev->bitmap_info.chunksize != to_bytes(rs->requested_bitmap_chunk_sectors)) {
    		r = bitmap_resize(mddev->bitmap, mddev->dev_sectors,
    				  to_bytes(rs->requested_bitmap_chunk_sectors), 0);
    		if (r)
    			DMERR("Failed to resize bitmap");
    	}
    
    	/* Check for any resize/reshape on @rs and adjust/initiate */
    	/* Be prepared for mddev_resume() in raid_resume() */
    	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    	if (mddev->recovery_cp && mddev->recovery_cp < MaxSector) {
    		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
    		mddev->resync_min = mddev->recovery_cp;
    	}
    
    	/* Check for any reshape request unless new raid set */
    	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
    		/* Initiate a reshape. */
    		rs_set_rdev_sectors(rs);
    		mddev_lock_nointr(mddev);
    		r = rs_start_reshape(rs);
    		mddev_unlock(mddev);
    		if (r)
    			DMWARN("Failed to check/start reshape, continuing without change");
    		r = 0;
    	}
    
    	return r;
    }
    
    static void raid_resume(struct dm_target *ti)
    {
    	struct raid_set *rs = ti->private;
    	struct mddev *mddev = &rs->md;
    
    	if (test_and_set_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {
    		/*
    		 * A secondary resume while the device is active.
    		 * Take this opportunity to check whether any failed
    		 * devices are reachable again.
    		 */
    		attempt_restore_of_faulty_devices(rs);
    	}
    
    	mddev->ro = 0;
    	mddev->in_sync = 0;
    
    	/* Only reduce raid set size before running a disk removing reshape. */
    	if (mddev->delta_disks < 0)
    		rs_set_capacity(rs);
    
    	/*
    	 * Keep the RAID set frozen if reshape/rebuild flags are set.
    	 * The RAID set is unfrozen once the next table load/resume,
    	 * which clears the reshape/rebuild flags, occurs.
    	 * This ensures that the constructor for the inactive table
    	 * retrieves an up-to-date reshape_position.
    	 */
    	if (!test_and_clear_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags) &&
    	    !(rs->ctr_flags & RESUME_STAY_FROZEN_FLAGS)) {
    		if (rs_is_reshapable(rs)) {
    			if (!rs_is_reshaping(rs) || _get_reshape_sectors(rs))
    				clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    		} else
    			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
    	}
    
    	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
    		mddev_lock_nointr(mddev);
    		mddev_resume(mddev);
    		mddev_unlock(mddev);
    	}
    }
    
    static struct target_type raid_target = {
    	.name = "raid",
    	.version = {1, 13, 0},
    	.module = THIS_MODULE,
    	.ctr = raid_ctr,
    	.dtr = raid_dtr,
    	.map = raid_map,
    	.status = raid_status,
    	.message = raid_message,
    	.iterate_devices = raid_iterate_devices,
    	.io_hints = raid_io_hints,
    	.postsuspend = raid_postsuspend,
    	.preresume = raid_preresume,
    	.resume = raid_resume,
    };
    
    static int __init dm_raid_init(void)
    {
    	DMINFO("Loading target version %u.%u.%u",
    	       raid_target.version[0],
    	       raid_target.version[1],
    	       raid_target.version[2]);
    	return dm_register_target(&raid_target);
    }
    
    static void __exit dm_raid_exit(void)
    {
    	dm_unregister_target(&raid_target);
    }
    
    module_init(dm_raid_init);
    module_exit(dm_raid_exit);
    
    module_param(devices_handle_discard_safely, bool, 0644);
    MODULE_PARM_DESC(devices_handle_discard_safely,
    		 "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
    
    MODULE_DESCRIPTION(DM_NAME " raid0/1/10/4/5/6 target");
    MODULE_ALIAS("dm-raid0");
    MODULE_ALIAS("dm-raid1");
    MODULE_ALIAS("dm-raid10");
    MODULE_ALIAS("dm-raid4");
    MODULE_ALIAS("dm-raid5");
    MODULE_ALIAS("dm-raid6");
    MODULE_AUTHOR("Neil Brown <dm-devel@redhat.com>");
    MODULE_AUTHOR("Heinz Mauelshagen <dm-devel@redhat.com>");
    MODULE_LICENSE("GPL");