/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
   md.h : kernel internal structure of the Linux MD driver
          Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman

*/

#ifndef _MD_MD_H
#define _MD_MD_H

#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/badblocks.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include "md-cluster.h"

#define MaxSector (~(sector_t)0)

/*
 * These flags should really be called "NO_RETRY" rather than
 * "FAILFAST" because they don't make any promise about time lapse,
 * only about the number of retries, which will be zero.
 * REQ_FAILFAST_DRIVER is not included because
 * Commit: 4a27446f3e39 ("[SCSI] modify scsi to handle new fail fast flags.")
 * seems to suggest that the errors it avoids retrying should usually
 * be retried.
 */
#define MD_FAILFAST     (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)

/*
 * The struct embedded in rdev is used to serialize IO.
 */
struct serial_in_rdev {
        struct rb_root_cached serial_rb;
        spinlock_t serial_lock;
        wait_queue_head_t serial_io_wait;
};

/*
 * MD's 'extended' device
 */
struct md_rdev {
        struct list_head same_set;      /* RAID devices within the same set */

        sector_t sectors;               /* Device size (in 512bytes sectors) */
        struct mddev *mddev;            /* RAID array if running */
        int last_events;                /* IO event timestamp */

        /*
         * If meta_bdev is non-NULL, it means that a separate device is
         * being used to store the metadata (superblock/bitmap) which
         * would otherwise be contained on the same device as the data (bdev).
         */
        struct block_device *meta_bdev;
        struct block_device *bdev;      /* block device handle */

        struct page     *sb_page, *bb_page;
        int             sb_loaded;
        __u64           sb_events;
        sector_t        data_offset;    /* start of data in array */
        sector_t        new_data_offset;/* only relevant while reshaping */
        sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
        int             sb_size;        /* bytes in the superblock */
        int             preferred_minor;        /* autorun support */

        struct kobject  kobj;

        /* A device can be in one of three states based on two flags:
         * Not working:   faulty==1 in_sync==0
         * Fully working: faulty==0 in_sync==1
         * Working, but not
         * in sync with array
         *                faulty==0 in_sync==0
         *
         * It can never have faulty==1, in_sync==1
         * This reduces the burden of testing multiple flags in many cases
         */

        unsigned long   flags;  /* bit set of 'enum flag_bits' bits. */
        wait_queue_head_t blocked_wait;

        int desc_nr;                    /* descriptor index in the superblock */
        int raid_disk;                  /* role of device in array */
        int new_raid_disk;              /* role that the device will have in
                                         * the array after a level-change completes.
                                         */
        int saved_raid_disk;            /* role that device used to have in the
                                         * array and could again if we did a partial
                                         * resync from the bitmap
                                         */
        union {
                sector_t recovery_offset;/* If this device has been partially
                                         * recovered, this is where we were
                                         * up to.
                                         */
                sector_t journal_tail;  /* If this device is a journal device,
                                         * this is the journal tail (journal
                                         * recovery start point)
                                         */
        };

        atomic_t        nr_pending;     /* number of pending requests.
                                         * only maintained for arrays that
                                         * support hot removal
                                         */
        atomic_t        read_errors;    /* number of consecutive read errors that
                                         * we have tried to ignore.
                                         */
        time64_t        last_read_error;        /* monotonic time since our
                                                 * last read error
                                                 */
        atomic_t        corrected_errors; /* number of corrected read errors,
                                           * for reporting to userspace and storing
                                           * in superblock.
                                           */

        struct serial_in_rdev *serial;  /* used for raid1 io serialization */

        struct work_struct del_work;    /* used for delayed sysfs removal */

        struct kernfs_node *sysfs_state; /* handle for 'state'
                                           * sysfs entry */
        /* handle for 'unacknowledged_bad_blocks' sysfs dentry */
        struct kernfs_node *sysfs_unack_badblocks;
        /* handle for 'bad_blocks' sysfs dentry */
        struct kernfs_node *sysfs_badblocks;
        struct badblocks badblocks;

        struct {
                short offset;   /* Offset from superblock to start of PPL.
                                 * Not used by external metadata. */
                unsigned int size;      /* Size in sectors of the PPL space */
                sector_t sector;        /* First sector of the PPL space */
        } ppl;
};
enum flag_bits {
        Faulty,                 /* device is known to have a fault */
        In_sync,                /* device is in_sync with rest of array */
        Bitmap_sync,            /* ..actually, not quite In_sync.  Need a
                                 * bitmap-based recovery to get fully in sync.
                                 * The bit is only meaningful before device
                                 * has been passed to pers->hot_add_disk.
                                 */
        WriteMostly,            /* Avoid reading if at all possible */
        AutoDetected,           /* added by auto-detect */
        Blocked,                /* An error occurred but has not yet
                                 * been acknowledged by the metadata
                                 * handler, so don't allow writes
                                 * until it is cleared */
        WriteErrorSeen,         /* A write error has been seen on this
                                 * device
                                 */
        FaultRecorded,          /* Intermediate state for clearing
                                 * Blocked.  The Fault is/will-be
                                 * recorded in the metadata, but that
                                 * metadata hasn't been stored safely
                                 * on disk yet.
                                 */
        BlockedBadBlocks,       /* A writer is blocked because they
                                 * found an unacknowledged bad-block.
                                 * This can safely be cleared at any
                                 * time, and the writer will re-check.
                                 * It may be set at any time, and at
                                 * worst the writer will timeout and
                                 * re-check.  So setting it as
                                 * accurately as possible is good, but
                                 * not absolutely critical.
                                 */
        WantReplacement,        /* This device is a candidate to be
                                 * hot-replaced, either because it has
                                 * reported some faults, or because
                                 * of explicit request.
                                 */
        Replacement,            /* This device is a replacement for
                                 * a want_replacement device with same
                                 * raid_disk number.
                                 */
        Candidate,              /* For clustered environments only:
                                 * This device is seen locally but not
                                 * by the whole cluster
                                 */
        Journal,                /* This device is used as journal for
                                 * raid-5/6.
                                 * Usually, this device should be faster
                                 * than other devices in the array
                                 */
        ClusterRemove,
        RemoveSynchronized,     /* synchronize_rcu() was called after
                                 * this device was known to be faulty,
                                 * so it is safe to remove without
                                 * another synchronize_rcu() call.
                                 */
        ExternalBbl,            /* External metadata provides bad
                                 * block management for a disk
                                 */
        FailFast,               /* Minimal retries should be attempted on
                                 * this device, so use REQ_FAILFAST_DEV.
                                 * Also don't try to repair failed reads.
                                 * It is expects that no bad block log
                                 * is present.
                                 */
        LastDev,                /* Seems to be the last working dev as
                                 * it didn't fail, so don't use FailFast
                                 * any more for metadata
                                 */
        CollisionCheck,         /*
                                 * check if there is collision between raid1
                                 * serial bios.
                                 */
};

static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
                              sector_t *first_bad, int *bad_sectors)
{
        if (unlikely(rdev->badblocks.count)) {
                int rv = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
                                        sectors,
                                        first_bad, bad_sectors);
                if (rv)
                        *first_bad -= rdev->data_offset;
                return rv;
        }
        return 0;
}
extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                              int is_new);
extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                                int is_new);
struct md_cluster_info;

/**
 * enum mddev_flags - md device flags.
 * @MD_ARRAY_FIRST_USE: First use of array, needs initialization.
 * @MD_CLOSING: If set, we are closing the array, do not open it then.
 * @MD_JOURNAL_CLEAN: A raid with journal is already clean.
 * @MD_HAS_JOURNAL: The raid array has journal feature set.
 * @MD_CLUSTER_RESYNC_LOCKED: cluster raid only, which means node, already took
 *                             resync lock, need to release the lock.
 * @MD_FAILFAST_SUPPORTED: Using MD_FAILFAST on metadata writes is supported as
 *                          calls to md_error() will never cause the array to
 *                          become failed.
 * @MD_HAS_PPL:  The raid array has PPL feature set.
 * @MD_HAS_MULTIPLE_PPLS: The raid array has multiple PPLs feature set.
 * @MD_ALLOW_SB_UPDATE: md_check_recovery is allowed to update the metadata
 *                       without taking reconfig_mutex.
 * @MD_UPDATING_SB: md_check_recovery is updating the metadata without
 *                   explicitly holding reconfig_mutex.
 * @MD_NOT_READY: do_md_run() is active, so 'array_state', ust not report that
 *                 array is ready yet.
 * @MD_BROKEN: This is used to stop writes and mark array as failed.
 *
 * change UNSUPPORTED_MDDEV_FLAGS for each array type if new flag is added
 */
enum mddev_flags {
        MD_ARRAY_FIRST_USE,
        MD_CLOSING,
        MD_JOURNAL_CLEAN,
        MD_HAS_JOURNAL,
        MD_CLUSTER_RESYNC_LOCKED,
        MD_FAILFAST_SUPPORTED,
        MD_HAS_PPL,
        MD_HAS_MULTIPLE_PPLS,
        MD_ALLOW_SB_UPDATE,
        MD_UPDATING_SB,
        MD_NOT_READY,
        MD_BROKEN,
};

enum mddev_sb_flags {
        MD_SB_CHANGE_DEVS,              /* Some device status has changed */
        MD_SB_CHANGE_CLEAN,     /* transition to or from 'clean' */
        MD_SB_CHANGE_PENDING,   /* switch from 'clean' to 'active' in progress */
        MD_SB_NEED_REWRITE,     /* metadata write needs to be repeated */
};

#define NR_SERIAL_INFOS         8
/* record current range of serialize IOs */
struct serial_info {
        struct rb_node node;
        sector_t start;         /* start sector of rb node */
        sector_t last;          /* end sector of rb node */
        sector_t _subtree_last; /* highest sector in subtree of rb node */
};

struct mddev {
        void                            *private;
        struct md_personality           *pers;
        dev_t                           unit;
        int                             md_minor;
        struct list_head                disks;
        unsigned long                   flags;
        unsigned long                   sb_flags;

        int                             suspended;
        atomic_t                        active_io;
        int                             ro;
        int                             sysfs_active; /* set when sysfs deletes
                                                       * are happening, so run/
                                                       * takeover/stop are not safe
                                                       */
        struct gendisk                  *gendisk;

        struct kobject                  kobj;
        int                             hold_active;
#define UNTIL_IOCTL     1
#define UNTIL_STOP      2

        /* Superblock information */
        int                             major_version,
                                        minor_version,
                                        patch_version;
        int                             persistent;
        int                             external;       /* metadata is
                                                         * managed externally */
        char                            metadata_type[17]; /* externally set*/
        int                             chunk_sectors;
        time64_t                        ctime, utime;
        int                             level, layout;
        char                            clevel[16];
        int                             raid_disks;
        int                             max_disks;
        sector_t                        dev_sectors;    /* used size of
                                                         * component devices */
        sector_t                        array_sectors; /* exported array size */
        int                             external_size; /* size managed
                                                        * externally */
        __u64                           events;
        /* If the last 'event' was simply a clean->dirty transition, and
         * we didn't write it to the spares, then it is safe and simple
         * to just decrement the event count on a dirty->clean transition.
         * So we record that possibility here.
         */
        int                             can_decrease_events;

        char                            uuid[16];

        /* If the array is being reshaped, we need to record the
         * new shape and an indication of where we are up to.
         * This is written to the superblock.
         * If reshape_position is MaxSector, then no reshape is happening (yet).
         */
        sector_t                        reshape_position;
        int                             delta_disks, new_level, new_layout;
        int                             new_chunk_sectors;
        int                             reshape_backwards;

        struct md_thread                *thread;        /* management thread */
        struct md_thread                *sync_thread;   /* doing resync or reconstruct */

        /* 'last_sync_action' is initialized to "none".  It is set when a
         * sync operation (i.e "data-check", "requested-resync", "resync",
         * "recovery", or "reshape") is started.  It holds this value even
         * when the sync thread is "frozen" (interrupted) or "idle" (stopped
         * or finished).  It is overwritten when a new sync operation is begun.
         */
        char                            *last_sync_action;
        sector_t                        curr_resync;    /* last block scheduled */
        /* As resync requests can complete out of order, we cannot easily track
         * how much resync has been completed.  So we occasionally pause until
         * everything completes, then set curr_resync_completed to curr_resync.
         * As such it may be well behind the real resync mark, but it is a value
         * we are certain of.
         */
        sector_t                        curr_resync_completed;
        unsigned long                   resync_mark;    /* a recent timestamp */
        sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
        sector_t                        curr_mark_cnt; /* blocks scheduled now */

        sector_t                        resync_max_sectors; /* may be set by personality */

        atomic64_t                      resync_mismatches; /* count of sectors where
                                                            * parity/replica mismatch found
                                                            */

        /* allow user-space to request suspension of IO to regions of the array */
        sector_t                        suspend_lo;
        sector_t                        suspend_hi;
        /* if zero, use the system-wide default */
        int                             sync_speed_min;
        int                             sync_speed_max;

        /* resync even though the same disks are shared among md-devices */
        int                             parallel_resync;

        int                             ok_start_degraded;

        unsigned long                   recovery;
        /* If a RAID personality determines that recovery (of a particular
         * device) will fail due to a read error on the source device, it
         * takes a copy of this number and does not attempt recovery again
         * until this number changes.
         */
        int                             recovery_disabled;

        int                             in_sync;        /* know to not need resync */
        /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
         * that we are never stopping an array while it is open.
         * 'reconfig_mutex' protects all other reconfiguration.
         * These locks are separate due to conflicting interactions
         * with disk->open_mutex.
         * Lock ordering is:
         *  reconfig_mutex -> disk->open_mutex
         *  disk->open_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
         */
        struct mutex                    open_mutex;
        struct mutex                    reconfig_mutex;
        atomic_t                        active;         /* general refcount */
        atomic_t                        openers;        /* number of active opens */

        int                             changed;        /* True if we might need to
                                                         * reread partition info */
        int                             degraded;       /* whether md should consider
                                                         * adding a spare
                                                         */

        atomic_t                        recovery_active; /* blocks scheduled, but not written */
        wait_queue_head_t               recovery_wait;
        sector_t                        recovery_cp;
        sector_t                        resync_min;     /* user requested sync
                                                         * starts here */
        sector_t                        resync_max;     /* resync should pause
                                                         * when it gets here */

        struct kernfs_node              *sysfs_state;   /* handle for 'array_state'
                                                         * file in sysfs.
                                                         */
        struct kernfs_node              *sysfs_action;  /* handle for 'sync_action' */
        struct kernfs_node              *sysfs_completed;       /*handle for 'sync_completed' */
        struct kernfs_node              *sysfs_degraded;        /*handle for 'degraded' */
        struct kernfs_node              *sysfs_level;           /*handle for 'level' */

        struct work_struct del_work;    /* used for delayed sysfs removal */

        /* "lock" protects:
         *   flush_bio transition from NULL to !NULL
         *   rdev superblocks, events
         *   clearing MD_CHANGE_*
         *   in_sync - and related safemode and MD_CHANGE changes
         *   pers (also protected by reconfig_mutex and pending IO).
         *   clearing ->bitmap
         *   clearing ->bitmap_info.file
         *   changing ->resync_{min,max}
         *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
         */
        spinlock_t                      lock;
        wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
        atomic_t                        pending_writes; /* number of active superblock writes */

        unsigned int                    safemode;       /* if set, update "clean" superblock
                                                         * when no writes pending.
                                                         */
        unsigned int                    safemode_delay;
        struct timer_list               safemode_timer;
        struct percpu_ref               writes_pending;
        int                             sync_checkers;  /* # of threads checking writes_pending */
        struct request_queue            *queue; /* for plugging ... */

        struct bitmap                   *bitmap; /* the bitmap for the device */
        struct {
                struct file             *file; /* the bitmap file */
                loff_t                  offset; /* offset from superblock of
                                                 * start of bitmap. May be
                                                 * negative, but not '0'
                                                 * For external metadata, offset
                                                 * from start of device.
                                                 */
                unsigned long           space; /* space available at this offset */
                loff_t                  default_offset; /* this is the offset to use when
                                                         * hot-adding a bitmap.  It should
                                                         * eventually be settable by sysfs.
                                                         */
                unsigned long           default_space; /* space available at
                                                        * default offset */
                struct mutex            mutex;
                unsigned long           chunksize;
                unsigned long           daemon_sleep; /* how many jiffies between updates? */
                unsigned long           max_write_behind; /* write-behind mode */
                int                     external;
                int                     nodes; /* Maximum number of nodes in the cluster */
                char                    cluster_name[64]; /* Name of the cluster */
        } bitmap_info;

        atomic_t                        max_corr_read_errors; /* max read retries */
        struct list_head                all_mddevs;

        const struct attribute_group    *to_remove;

        struct bio_set                  bio_set;
        struct bio_set                  sync_set; /* for sync operations like
                                                   * metadata and bitmap writes
                                                   */
        struct bio_set                  io_acct_set; /* for raid0 and raid5 io accounting */

        /* Generic flush handling.
         * The last to finish preflush schedules a worker to submit
         * the rest of the request (without the REQ_PREFLUSH flag).
         */
        struct bio *flush_bio;
        atomic_t flush_pending;
        ktime_t start_flush, prev_flush_start; /* prev_flush_start is when the previous completed
                                                * flush was started.
                                                */
        struct work_struct flush_work;
        struct work_struct event_work;  /* used by dm to report failure event */
        mempool_t *serial_info_pool;
        void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
        struct md_cluster_info          *cluster_info;
        unsigned int                    good_device_nr; /* good device num within cluster raid */
        unsigned int                    noio_flag; /* for memalloc scope API */

        bool    has_superblocks:1;
        bool    fail_last_dev:1;
        bool    serialize_policy:1;
};

enum recovery_flags {
        /*
         * If neither SYNC or RESHAPE are set, then it is a recovery.
         */
        MD_RECOVERY_RUNNING,    /* a thread is running, or about to be started */
        MD_RECOVERY_SYNC,       /* actually doing a resync, not a recovery */
        MD_RECOVERY_RECOVER,    /* doing recovery, or need to try it. */
        MD_RECOVERY_INTR,       /* resync needs to be aborted for some reason */
        MD_RECOVERY_DONE,       /* thread is done and is waiting to be reaped */
        MD_RECOVERY_NEEDED,     /* we might need to start a resync/recover */
        MD_RECOVERY_REQUESTED,  /* user-space has requested a sync (used with SYNC) */
        MD_RECOVERY_CHECK,      /* user-space request for check-only, no repair */
        MD_RECOVERY_RESHAPE,    /* A reshape is happening */
        MD_RECOVERY_FROZEN,     /* User request to abort, and not restart, any action */
        MD_RECOVERY_ERROR,      /* sync-action interrupted because io-error */
        MD_RECOVERY_WAIT,       /* waiting for pers->start() to finish */
        MD_RESYNCING_REMOTE,    /* remote node is running resync thread */
};

static inline int __must_check mddev_lock(struct mddev *mddev)
{
        return mutex_lock_interruptible(&mddev->reconfig_mutex);
}

/* Sometimes we need to take the lock in a situation where
 * failure due to interrupts is not acceptable.
 */
static inline void mddev_lock_nointr(struct mddev *mddev)
{
        mutex_lock(&mddev->reconfig_mutex);
}

static inline int mddev_trylock(struct mddev *mddev)
{
        return mutex_trylock(&mddev->reconfig_mutex);
}
extern void mddev_unlock(struct mddev *mddev);

static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
{
        atomic_add(nr_sectors, &bdev->bd_disk->sync_io);
}

static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
{
        md_sync_acct(bio->bi_bdev, nr_sectors);
}

struct md_personality
{
        char *name;
        int level;
        struct list_head list;
        struct module *owner;
        bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);
        /*
         * start up works that do NOT require md_thread. tasks that
         * requires md_thread should go into start()
         */
        int (*run)(struct mddev *mddev);
        /* start up works that require md threads */
        int (*start)(struct mddev *mddev);
        void (*free)(struct mddev *mddev, void *priv);
        void (*status)(struct seq_file *seq, struct mddev *mddev);
        /* error_handler must set ->faulty and clear ->in_sync
         * if appropriate, and should abort recovery if needed
         */
        void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
        int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
        int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
        int (*spare_active) (struct mddev *mddev);
        sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
        int (*resize) (struct mddev *mddev, sector_t sectors);
        sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
        int (*check_reshape) (struct mddev *mddev);
        int (*start_reshape) (struct mddev *mddev);
        void (*finish_reshape) (struct mddev *mddev);
        void (*update_reshape_pos) (struct mddev *mddev);
        /* quiesce suspends or resumes internal processing.
         * 1 - stop new actions and wait for action io to complete
         * 0 - return to normal behaviour
         */
        void (*quiesce) (struct mddev *mddev, int quiesce);
        /* takeover is used to transition an array from one
         * personality to another.  The new personality must be able
         * to handle the data in the current layout.
         * e.g. 2drive raid1 -> 2drive raid5
         *      ndrive raid5 -> degraded n+1drive raid6 with special layout
         * If the takeover succeeds, a new 'private' structure is returned.
         * This needs to be installed and then ->run used to activate the
         * array.
         */
        void *(*takeover) (struct mddev *mddev);
        /* Changes the consistency policy of an active array. */
        int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
};

struct md_sysfs_entry {
        struct attribute attr;
        ssize_t (*show)(struct mddev *, char *);
        ssize_t (*store)(struct mddev *, const char *, size_t);
};
extern const struct attribute_group md_bitmap_group;

static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
{
        if (sd)
                return sysfs_get_dirent(sd, name);
        return sd;
}
static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
{
        if (sd)
                sysfs_notify_dirent(sd);
}

static inline char * mdname (struct mddev * mddev)
{
        return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
}

static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
        char nm[20];
        if (!test_bit(Replacement, &rdev->flags) &&
            !test_bit(Journal, &rdev->flags) &&
            mddev->kobj.sd) {
                sprintf(nm, "rd%d", rdev->raid_disk);
                return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
        } else
                return 0;
}

static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
        char nm[20];
        if (!test_bit(Replacement, &rdev->flags) &&
            !test_bit(Journal, &rdev->flags) &&
            mddev->kobj.sd) {
                sprintf(nm, "rd%d", rdev->raid_disk);
                sysfs_remove_link(&mddev->kobj, nm);
        }
}

/*
 * iterates through some rdev ringlist. It's safe to remove the
 * current 'rdev'. Dont touch 'tmp' though.
 */
#define rdev_for_each_list(rdev, tmp, head)                             \
        list_for_each_entry_safe(rdev, tmp, head, same_set)

/*
 * iterates through the 'same array disks' ringlist
 */
#define rdev_for_each(rdev, mddev)                              \
        list_for_each_entry(rdev, &((mddev)->disks), same_set)

#define rdev_for_each_safe(rdev, tmp, mddev)                            \
        list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)

#define rdev_for_each_rcu(rdev, mddev)                          \
        list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)

struct md_thread {
        void                    (*run) (struct md_thread *thread);
        struct mddev            *mddev;
        wait_queue_head_t       wqueue;
        unsigned long           flags;
        struct task_struct      *tsk;
        unsigned long           timeout;
        void                    *private;
};

struct md_io_acct {
        struct bio *orig_bio;
        unsigned long start_time;
        struct bio bio_clone;
};

#define THREAD_WAKEUP  0

static inline void safe_put_page(struct page *p)
{
        if (p) put_page(p);
}

extern int register_md_personality(struct md_personality *p);
extern int unregister_md_personality(struct md_personality *p);
extern int register_md_cluster_operations(struct md_cluster_operations *ops,
                struct module *module);
extern int unregister_md_cluster_operations(void);
extern int md_setup_cluster(struct mddev *mddev, int nodes);
extern void md_cluster_stop(struct mddev *mddev);
extern struct md_thread *md_register_thread(
        void (*run)(struct md_thread *thread),
        struct mddev *mddev,
        const char *name);
extern void md_unregister_thread(struct md_thread **threadp);
extern void md_wakeup_thread(struct md_thread *thread);
extern void md_check_recovery(struct mddev *mddev);
extern void md_reap_sync_thread(struct mddev *mddev);
extern int mddev_init_writes_pending(struct mddev *mddev);
extern bool md_write_start(struct mddev *mddev, struct bio *bi);
extern void md_write_inc(struct mddev *mddev, struct bio *bi);
extern void md_write_end(struct mddev *mddev);
extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
extern void md_finish_reshape(struct mddev *mddev);
void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
                        struct bio *bio, sector_t start, sector_t size);
int acct_bioset_init(struct mddev *mddev);
void acct_bioset_exit(struct mddev *mddev);
void md_account_bio(struct mddev *mddev, struct bio **bio);

extern bool __must_check md_flush_request(struct mddev *mddev, struct bio *bio);
extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
                           sector_t sector, int size, struct page *page);
extern int md_super_wait(struct mddev *mddev);
extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
                        struct page *page, int op, int op_flags,
                        bool metadata_op);
extern void md_do_sync(struct md_thread *thread);
extern void md_new_event(void);
extern void md_allow_write(struct mddev *mddev);
extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
extern int md_check_no_bitmap(struct mddev *mddev);
extern int md_integrity_register(struct mddev *mddev);
extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);

extern void mddev_init(struct mddev *mddev);
extern int md_run(struct mddev *mddev);
extern int md_start(struct mddev *mddev);
extern void md_stop(struct mddev *mddev);
extern void md_stop_writes(struct mddev *mddev);
extern int md_rdev_init(struct md_rdev *rdev);
extern void md_rdev_clear(struct md_rdev *rdev);

extern void md_handle_request(struct mddev *mddev, struct bio *bio);
extern void mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);

extern void md_reload_sb(struct mddev *mddev, int raid_disk);
extern void md_update_sb(struct mddev *mddev, int force);
extern void md_kick_rdev_from_array(struct md_rdev * rdev);
extern void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                                     bool is_suspend);
extern void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
                                      bool is_suspend);
struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev);

static inline bool is_mddev_broken(struct md_rdev *rdev, const char *md_type)
{
        if (!disk_live(rdev->bdev->bd_disk)) {
                if (!test_and_set_bit(MD_BROKEN, &rdev->mddev->flags))
                        pr_warn("md: %s: %s array has a missing/failed member\n",
                                mdname(rdev->mddev), md_type);
                return true;
        }
        return false;
}

static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
{
        int faulty = test_bit(Faulty, &rdev->flags);
        if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                md_wakeup_thread(mddev->thread);
        }
}

extern struct md_cluster_operations *md_cluster_ops;
static inline int mddev_is_clustered(struct mddev *mddev)
{
        return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
}

/* clear unsupported mddev_flags */
static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
        unsigned long unsupported_flags)
{
        mddev->flags &= ~unsupported_flags;
}

static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
{
        if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
            !bio->bi_bdev->bd_disk->queue->limits.max_write_zeroes_sectors)
                mddev->queue->limits.max_write_zeroes_sectors = 0;
}

struct mdu_array_info_s;
struct mdu_disk_info_s;

extern int mdp_major;
void md_autostart_arrays(int part);
int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info);
int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info);
int do_md_run(struct mddev *mddev);

extern const struct block_device_operations md_fops;

#endif /* _MD_MD_H */