/*
   md.h : kernel internal structure of the Linux MD driver
          Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
          
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
   
   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
*/

#ifndef _MD_MD_H
#define _MD_MD_H

#include <linux/blkdev.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>

#define MaxSector (~(sector_t)0)

/* Bad block numbers are stored sorted in a single page.
 * 64bits is used for each block or extent.
 * 54 bits are sector number, 9 bits are extent size,
 * 1 bit is an 'acknowledged' flag.
 */
#define MD_MAX_BADBLOCKS        (PAGE_SIZE/8)

/*
 * 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
                                         */
        sector_t        recovery_offset;/* If this device has been partially
                                         * recovered, this is where we were
                                         * up to.
                                         */

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

        struct kernfs_node *sysfs_state; /* handle for 'state'
                                           * sysfs entry */

        struct badblocks {
                int     count;          /* count of bad blocks */
                int     unacked_exist;  /* there probably are unacknowledged
                                         * bad blocks.  This is only cleared
                                         * when a read discovers none
                                         */
                int     shift;          /* shift from sectors to block size
                                         * a -ve shift means badblocks are
                                         * disabled.*/
                u64     *page;          /* badblock list */
                int     changed;
                seqlock_t lock;

                sector_t sector;
                sector_t size;          /* in sectors */
        } badblocks;
};
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
                                 */
        Unmerged,               /* device is being added to array and should
                                 * be considerred for bvec_merge_fn but not
                                 * yet for actual IO
                                 */
        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.
                                 */
};

#define BB_LEN_MASK     (0x00000000000001FFULL)
#define BB_OFFSET_MASK  (0x7FFFFFFFFFFFFE00ULL)
#define BB_ACK_MASK     (0x8000000000000000ULL)
#define BB_MAX_LEN      512
#define BB_OFFSET(x)    (((x) & BB_OFFSET_MASK) >> 9)
#define BB_LEN(x)       (((x) & BB_LEN_MASK) + 1)
#define BB_ACK(x)       (!!((x) & BB_ACK_MASK))
#define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))

extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
                          sector_t *first_bad, int *bad_sectors);
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 = md_is_badblock(&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);
extern void md_ack_all_badblocks(struct badblocks *bb);

struct mddev {
        void                            *private;
        struct md_personality           *pers;
        dev_t                           unit;
        int                             md_minor;
        struct list_head                disks;
        unsigned long                   flags;
#define MD_CHANGE_DEVS  0       /* Some device status has changed */
#define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
#define MD_CHANGE_PENDING 2     /* switch from 'clean' to 'active' in progress */
#define MD_UPDATE_SB_FLAGS (1 | 2 | 4)  /* If these are set, md_update_sb needed */
#define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
#define MD_STILL_CLOSED 4       /* If set, then array has not been opened since
                                 * md_ioctl checked on it.
                                 */

        int                             suspended;
        atomic_t                        active_io;
        int                             ro;
        int                             sysfs_active; /* set when sysfs deletes
                                                       * are happening, so run/
                                                       * takeover/stop are not safe
                                                       */
        int                             ready; /* See when safe to pass
                                                * IO requests down */
        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;
        time_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;
        /* recovery/resync flags 
         * NEEDED:   we might need to start a resync/recover
         * RUNNING:  a thread is running, or about to be started
         * SYNC:     actually doing a resync, not a recovery
         * RECOVER:  doing recovery, or need to try it.
         * INTR:     resync needs to be aborted for some reason
         * DONE:     thread is done and is waiting to be reaped
         * REQUEST:  user-space has requested a sync (used with SYNC)
         * CHECK:    user-space request for check-only, no repair
         * RESHAPE:  A reshape is happening
         * ERROR:    sync-action interrupted because io-error
         *
         * If neither SYNC or RESHAPE are set, then it is a recovery.
         */
#define MD_RECOVERY_RUNNING     0
#define MD_RECOVERY_SYNC        1
#define MD_RECOVERY_RECOVER     2
#define MD_RECOVERY_INTR        3
#define MD_RECOVERY_DONE        4
#define MD_RECOVERY_NEEDED      5
#define MD_RECOVERY_REQUESTED   6
#define MD_RECOVERY_CHECK       7
#define MD_RECOVERY_RESHAPE     8
#define MD_RECOVERY_FROZEN      9
#define MD_RECOVERY_ERROR       10

        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 bdev->bd_mutex.
         * Lock ordering is:
         *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
         *  bd_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
                                                         */
        int                             merge_check_needed; /* at least one
                                                             * member device
                                                             * has a
                                                             * merge_bvec_fn */

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

        spinlock_t                      write_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;
        atomic_t                        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;
        } bitmap_info;

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

        struct attribute_group          *to_remove;

        struct bio_set                  *bio_set;

        /* Generic flush handling.
         * The last to finish preflush schedules a worker to submit
         * the rest of the request (without the REQ_FLUSH flag).
         */
        struct bio *flush_bio;
        atomic_t flush_pending;
        struct work_struct flush_work;
        struct work_struct event_work;  /* used by dm to report failure event */
        void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
};


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);
}

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

struct md_personality
{
        char *name;
        int level;
        struct list_head list;
        struct module *owner;
        void (*make_request)(struct mddev *mddev, struct bio *bio);
        int (*run)(struct mddev *mddev);
        int (*stop)(struct mddev *mddev);
        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 go_faster);
        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);
        /* quiesce moves between quiescence states
         * 0 - fully active
         * 1 - no new requests allowed
         * others - reserved
         */
        void (*quiesce) (struct mddev *mddev, int state);
        /* 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);
};


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

#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 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 void md_write_start(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);

extern int mddev_congested(struct mddev *mddev, int bits);
extern void 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 void md_super_wait(struct mddev *mddev);
extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size, 
                        struct page *page, int rw, bool metadata_op);
extern void md_do_sync(struct md_thread *thread);
extern void md_new_event(struct mddev *mddev);
extern int 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 void 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 restore_bitmap_write_access(struct file *file);

extern void mddev_init(struct mddev *mddev);
extern int md_run(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 mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);
extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
                                   struct mddev *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
                                   struct mddev *mddev);

extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
static inline int mddev_check_plugged(struct mddev *mddev)
{
        return !!blk_check_plugged(md_unplug, mddev,
                                   sizeof(struct blk_plug_cb));
}
#endif /* _MD_MD_H */