linux/drivers/md/md.h
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   1/*
   2   md.h : kernel internal structure of the Linux MD driver
   3          Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2, or (at your option)
   8   any later version.
   9
  10   You should have received a copy of the GNU General Public License
  11   (for example /usr/src/linux/COPYING); if not, write to the Free
  12   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  13*/
  14
  15#ifndef _MD_MD_H
  16#define _MD_MD_H
  17
  18#include <linux/blkdev.h>
  19#include <linux/backing-dev.h>
  20#include <linux/badblocks.h>
  21#include <linux/kobject.h>
  22#include <linux/list.h>
  23#include <linux/mm.h>
  24#include <linux/mutex.h>
  25#include <linux/timer.h>
  26#include <linux/wait.h>
  27#include <linux/workqueue.h>
  28#include "md-cluster.h"
  29
  30#define MaxSector (~(sector_t)0)
  31
  32/*
  33 * MD's 'extended' device
  34 */
  35struct md_rdev {
  36        struct list_head same_set;      /* RAID devices within the same set */
  37
  38        sector_t sectors;               /* Device size (in 512bytes sectors) */
  39        struct mddev *mddev;            /* RAID array if running */
  40        int last_events;                /* IO event timestamp */
  41
  42        /*
  43         * If meta_bdev is non-NULL, it means that a separate device is
  44         * being used to store the metadata (superblock/bitmap) which
  45         * would otherwise be contained on the same device as the data (bdev).
  46         */
  47        struct block_device *meta_bdev;
  48        struct block_device *bdev;      /* block device handle */
  49
  50        struct page     *sb_page, *bb_page;
  51        int             sb_loaded;
  52        __u64           sb_events;
  53        sector_t        data_offset;    /* start of data in array */
  54        sector_t        new_data_offset;/* only relevant while reshaping */
  55        sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  56        int             sb_size;        /* bytes in the superblock */
  57        int             preferred_minor;        /* autorun support */
  58
  59        struct kobject  kobj;
  60
  61        /* A device can be in one of three states based on two flags:
  62         * Not working:   faulty==1 in_sync==0
  63         * Fully working: faulty==0 in_sync==1
  64         * Working, but not
  65         * in sync with array
  66         *                faulty==0 in_sync==0
  67         *
  68         * It can never have faulty==1, in_sync==1
  69         * This reduces the burden of testing multiple flags in many cases
  70         */
  71
  72        unsigned long   flags;  /* bit set of 'enum flag_bits' bits. */
  73        wait_queue_head_t blocked_wait;
  74
  75        int desc_nr;                    /* descriptor index in the superblock */
  76        int raid_disk;                  /* role of device in array */
  77        int new_raid_disk;              /* role that the device will have in
  78                                         * the array after a level-change completes.
  79                                         */
  80        int saved_raid_disk;            /* role that device used to have in the
  81                                         * array and could again if we did a partial
  82                                         * resync from the bitmap
  83                                         */
  84        union {
  85                sector_t recovery_offset;/* If this device has been partially
  86                                         * recovered, this is where we were
  87                                         * up to.
  88                                         */
  89                sector_t journal_tail;  /* If this device is a journal device,
  90                                         * this is the journal tail (journal
  91                                         * recovery start point)
  92                                         */
  93        };
  94
  95        atomic_t        nr_pending;     /* number of pending requests.
  96                                         * only maintained for arrays that
  97                                         * support hot removal
  98                                         */
  99        atomic_t        read_errors;    /* number of consecutive read errors that
 100                                         * we have tried to ignore.
 101                                         */
 102        time64_t        last_read_error;        /* monotonic time since our
 103                                                 * last read error
 104                                                 */
 105        atomic_t        corrected_errors; /* number of corrected read errors,
 106                                           * for reporting to userspace and storing
 107                                           * in superblock.
 108                                           */
 109        struct work_struct del_work;    /* used for delayed sysfs removal */
 110
 111        struct kernfs_node *sysfs_state; /* handle for 'state'
 112                                           * sysfs entry */
 113
 114        struct badblocks badblocks;
 115};
 116enum flag_bits {
 117        Faulty,                 /* device is known to have a fault */
 118        In_sync,                /* device is in_sync with rest of array */
 119        Bitmap_sync,            /* ..actually, not quite In_sync.  Need a
 120                                 * bitmap-based recovery to get fully in sync
 121                                 */
 122        WriteMostly,            /* Avoid reading if at all possible */
 123        AutoDetected,           /* added by auto-detect */
 124        Blocked,                /* An error occurred but has not yet
 125                                 * been acknowledged by the metadata
 126                                 * handler, so don't allow writes
 127                                 * until it is cleared */
 128        WriteErrorSeen,         /* A write error has been seen on this
 129                                 * device
 130                                 */
 131        FaultRecorded,          /* Intermediate state for clearing
 132                                 * Blocked.  The Fault is/will-be
 133                                 * recorded in the metadata, but that
 134                                 * metadata hasn't been stored safely
 135                                 * on disk yet.
 136                                 */
 137        BlockedBadBlocks,       /* A writer is blocked because they
 138                                 * found an unacknowledged bad-block.
 139                                 * This can safely be cleared at any
 140                                 * time, and the writer will re-check.
 141                                 * It may be set at any time, and at
 142                                 * worst the writer will timeout and
 143                                 * re-check.  So setting it as
 144                                 * accurately as possible is good, but
 145                                 * not absolutely critical.
 146                                 */
 147        WantReplacement,        /* This device is a candidate to be
 148                                 * hot-replaced, either because it has
 149                                 * reported some faults, or because
 150                                 * of explicit request.
 151                                 */
 152        Replacement,            /* This device is a replacement for
 153                                 * a want_replacement device with same
 154                                 * raid_disk number.
 155                                 */
 156        Candidate,              /* For clustered environments only:
 157                                 * This device is seen locally but not
 158                                 * by the whole cluster
 159                                 */
 160        Journal,                /* This device is used as journal for
 161                                 * raid-5/6.
 162                                 * Usually, this device should be faster
 163                                 * than other devices in the array
 164                                 */
 165        ClusterRemove,
 166        RemoveSynchronized,     /* synchronize_rcu() was called after
 167                                 * this device was known to be faulty,
 168                                 * so it is safe to remove without
 169                                 * another synchronize_rcu() call.
 170                                 */
 171};
 172
 173static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
 174                              sector_t *first_bad, int *bad_sectors)
 175{
 176        if (unlikely(rdev->badblocks.count)) {
 177                int rv = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
 178                                        sectors,
 179                                        first_bad, bad_sectors);
 180                if (rv)
 181                        *first_bad -= rdev->data_offset;
 182                return rv;
 183        }
 184        return 0;
 185}
 186extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 187                              int is_new);
 188extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 189                                int is_new);
 190struct md_cluster_info;
 191
 192struct mddev {
 193        void                            *private;
 194        struct md_personality           *pers;
 195        dev_t                           unit;
 196        int                             md_minor;
 197        struct list_head                disks;
 198        unsigned long                   flags;
 199#define MD_CHANGE_DEVS  0       /* Some device status has changed */
 200#define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 201#define MD_CHANGE_PENDING 2     /* switch from 'clean' to 'active' in progress */
 202#define MD_UPDATE_SB_FLAGS (1 | 2 | 4)  /* If these are set, md_update_sb needed */
 203#define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
 204#define MD_STILL_CLOSED 4       /* If set, then array has not been opened since
 205                                 * md_ioctl checked on it.
 206                                 */
 207#define MD_JOURNAL_CLEAN 5      /* A raid with journal is already clean */
 208#define MD_HAS_JOURNAL  6       /* The raid array has journal feature set */
 209#define MD_RELOAD_SB    7       /* Reload the superblock because another node
 210                                 * updated it.
 211                                 */
 212#define MD_CLUSTER_RESYNC_LOCKED 8 /* cluster raid only, which means node
 213                                    * already took resync lock, need to
 214                                    * release the lock */
 215
 216        int                             suspended;
 217        atomic_t                        active_io;
 218        int                             ro;
 219        int                             sysfs_active; /* set when sysfs deletes
 220                                                       * are happening, so run/
 221                                                       * takeover/stop are not safe
 222                                                       */
 223        struct gendisk                  *gendisk;
 224
 225        struct kobject                  kobj;
 226        int                             hold_active;
 227#define UNTIL_IOCTL     1
 228#define UNTIL_STOP      2
 229
 230        /* Superblock information */
 231        int                             major_version,
 232                                        minor_version,
 233                                        patch_version;
 234        int                             persistent;
 235        int                             external;       /* metadata is
 236                                                         * managed externally */
 237        char                            metadata_type[17]; /* externally set*/
 238        int                             chunk_sectors;
 239        time64_t                        ctime, utime;
 240        int                             level, layout;
 241        char                            clevel[16];
 242        int                             raid_disks;
 243        int                             max_disks;
 244        sector_t                        dev_sectors;    /* used size of
 245                                                         * component devices */
 246        sector_t                        array_sectors; /* exported array size */
 247        int                             external_size; /* size managed
 248                                                        * externally */
 249        __u64                           events;
 250        /* If the last 'event' was simply a clean->dirty transition, and
 251         * we didn't write it to the spares, then it is safe and simple
 252         * to just decrement the event count on a dirty->clean transition.
 253         * So we record that possibility here.
 254         */
 255        int                             can_decrease_events;
 256
 257        char                            uuid[16];
 258
 259        /* If the array is being reshaped, we need to record the
 260         * new shape and an indication of where we are up to.
 261         * This is written to the superblock.
 262         * If reshape_position is MaxSector, then no reshape is happening (yet).
 263         */
 264        sector_t                        reshape_position;
 265        int                             delta_disks, new_level, new_layout;
 266        int                             new_chunk_sectors;
 267        int                             reshape_backwards;
 268
 269        struct md_thread                *thread;        /* management thread */
 270        struct md_thread                *sync_thread;   /* doing resync or reconstruct */
 271
 272        /* 'last_sync_action' is initialized to "none".  It is set when a
 273         * sync operation (i.e "data-check", "requested-resync", "resync",
 274         * "recovery", or "reshape") is started.  It holds this value even
 275         * when the sync thread is "frozen" (interrupted) or "idle" (stopped
 276         * or finished).  It is overwritten when a new sync operation is begun.
 277         */
 278        char                            *last_sync_action;
 279        sector_t                        curr_resync;    /* last block scheduled */
 280        /* As resync requests can complete out of order, we cannot easily track
 281         * how much resync has been completed.  So we occasionally pause until
 282         * everything completes, then set curr_resync_completed to curr_resync.
 283         * As such it may be well behind the real resync mark, but it is a value
 284         * we are certain of.
 285         */
 286        sector_t                        curr_resync_completed;
 287        unsigned long                   resync_mark;    /* a recent timestamp */
 288        sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 289        sector_t                        curr_mark_cnt; /* blocks scheduled now */
 290
 291        sector_t                        resync_max_sectors; /* may be set by personality */
 292
 293        atomic64_t                      resync_mismatches; /* count of sectors where
 294                                                            * parity/replica mismatch found
 295                                                            */
 296
 297        /* allow user-space to request suspension of IO to regions of the array */
 298        sector_t                        suspend_lo;
 299        sector_t                        suspend_hi;
 300        /* if zero, use the system-wide default */
 301        int                             sync_speed_min;
 302        int                             sync_speed_max;
 303
 304        /* resync even though the same disks are shared among md-devices */
 305        int                             parallel_resync;
 306
 307        int                             ok_start_degraded;
 308        /* recovery/resync flags
 309         * NEEDED:   we might need to start a resync/recover
 310         * RUNNING:  a thread is running, or about to be started
 311         * SYNC:     actually doing a resync, not a recovery
 312         * RECOVER:  doing recovery, or need to try it.
 313         * INTR:     resync needs to be aborted for some reason
 314         * DONE:     thread is done and is waiting to be reaped
 315         * REQUEST:  user-space has requested a sync (used with SYNC)
 316         * CHECK:    user-space request for check-only, no repair
 317         * RESHAPE:  A reshape is happening
 318         * ERROR:    sync-action interrupted because io-error
 319         *
 320         * If neither SYNC or RESHAPE are set, then it is a recovery.
 321         */
 322#define MD_RECOVERY_RUNNING     0
 323#define MD_RECOVERY_SYNC        1
 324#define MD_RECOVERY_RECOVER     2
 325#define MD_RECOVERY_INTR        3
 326#define MD_RECOVERY_DONE        4
 327#define MD_RECOVERY_NEEDED      5
 328#define MD_RECOVERY_REQUESTED   6
 329#define MD_RECOVERY_CHECK       7
 330#define MD_RECOVERY_RESHAPE     8
 331#define MD_RECOVERY_FROZEN      9
 332#define MD_RECOVERY_ERROR       10
 333
 334        unsigned long                   recovery;
 335        /* If a RAID personality determines that recovery (of a particular
 336         * device) will fail due to a read error on the source device, it
 337         * takes a copy of this number and does not attempt recovery again
 338         * until this number changes.
 339         */
 340        int                             recovery_disabled;
 341
 342        int                             in_sync;        /* know to not need resync */
 343        /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 344         * that we are never stopping an array while it is open.
 345         * 'reconfig_mutex' protects all other reconfiguration.
 346         * These locks are separate due to conflicting interactions
 347         * with bdev->bd_mutex.
 348         * Lock ordering is:
 349         *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 350         *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 351         */
 352        struct mutex                    open_mutex;
 353        struct mutex                    reconfig_mutex;
 354        atomic_t                        active;         /* general refcount */
 355        atomic_t                        openers;        /* number of active opens */
 356
 357        int                             changed;        /* True if we might need to
 358                                                         * reread partition info */
 359        int                             degraded;       /* whether md should consider
 360                                                         * adding a spare
 361                                                         */
 362
 363        atomic_t                        recovery_active; /* blocks scheduled, but not written */
 364        wait_queue_head_t               recovery_wait;
 365        sector_t                        recovery_cp;
 366        sector_t                        resync_min;     /* user requested sync
 367                                                         * starts here */
 368        sector_t                        resync_max;     /* resync should pause
 369                                                         * when it gets here */
 370
 371        struct kernfs_node              *sysfs_state;   /* handle for 'array_state'
 372                                                         * file in sysfs.
 373                                                         */
 374        struct kernfs_node              *sysfs_action;  /* handle for 'sync_action' */
 375
 376        struct work_struct del_work;    /* used for delayed sysfs removal */
 377
 378        /* "lock" protects:
 379         *   flush_bio transition from NULL to !NULL
 380         *   rdev superblocks, events
 381         *   clearing MD_CHANGE_*
 382         *   in_sync - and related safemode and MD_CHANGE changes
 383         *   pers (also protected by reconfig_mutex and pending IO).
 384         *   clearing ->bitmap
 385         *   clearing ->bitmap_info.file
 386         *   changing ->resync_{min,max}
 387         *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
 388         */
 389        spinlock_t                      lock;
 390        wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 391        atomic_t                        pending_writes; /* number of active superblock writes */
 392
 393        unsigned int                    safemode;       /* if set, update "clean" superblock
 394                                                         * when no writes pending.
 395                                                         */
 396        unsigned int                    safemode_delay;
 397        struct timer_list               safemode_timer;
 398        atomic_t                        writes_pending;
 399        struct request_queue            *queue; /* for plugging ... */
 400
 401        struct bitmap                   *bitmap; /* the bitmap for the device */
 402        struct {
 403                struct file             *file; /* the bitmap file */
 404                loff_t                  offset; /* offset from superblock of
 405                                                 * start of bitmap. May be
 406                                                 * negative, but not '0'
 407                                                 * For external metadata, offset
 408                                                 * from start of device.
 409                                                 */
 410                unsigned long           space; /* space available at this offset */
 411                loff_t                  default_offset; /* this is the offset to use when
 412                                                         * hot-adding a bitmap.  It should
 413                                                         * eventually be settable by sysfs.
 414                                                         */
 415                unsigned long           default_space; /* space available at
 416                                                        * default offset */
 417                struct mutex            mutex;
 418                unsigned long           chunksize;
 419                unsigned long           daemon_sleep; /* how many jiffies between updates? */
 420                unsigned long           max_write_behind; /* write-behind mode */
 421                int                     external;
 422                int                     nodes; /* Maximum number of nodes in the cluster */
 423                char                    cluster_name[64]; /* Name of the cluster */
 424        } bitmap_info;
 425
 426        atomic_t                        max_corr_read_errors; /* max read retries */
 427        struct list_head                all_mddevs;
 428
 429        struct attribute_group          *to_remove;
 430
 431        struct bio_set                  *bio_set;
 432
 433        /* Generic flush handling.
 434         * The last to finish preflush schedules a worker to submit
 435         * the rest of the request (without the REQ_PREFLUSH flag).
 436         */
 437        struct bio *flush_bio;
 438        atomic_t flush_pending;
 439        struct work_struct flush_work;
 440        struct work_struct event_work;  /* used by dm to report failure event */
 441        void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 442        struct md_cluster_info          *cluster_info;
 443        unsigned int                    good_device_nr; /* good device num within cluster raid */
 444};
 445
 446static inline int __must_check mddev_lock(struct mddev *mddev)
 447{
 448        return mutex_lock_interruptible(&mddev->reconfig_mutex);
 449}
 450
 451/* Sometimes we need to take the lock in a situation where
 452 * failure due to interrupts is not acceptable.
 453 */
 454static inline void mddev_lock_nointr(struct mddev *mddev)
 455{
 456        mutex_lock(&mddev->reconfig_mutex);
 457}
 458
 459static inline int mddev_is_locked(struct mddev *mddev)
 460{
 461        return mutex_is_locked(&mddev->reconfig_mutex);
 462}
 463
 464static inline int mddev_trylock(struct mddev *mddev)
 465{
 466        return mutex_trylock(&mddev->reconfig_mutex);
 467}
 468extern void mddev_unlock(struct mddev *mddev);
 469
 470static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 471{
 472        atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 473}
 474
 475struct md_personality
 476{
 477        char *name;
 478        int level;
 479        struct list_head list;
 480        struct module *owner;
 481        void (*make_request)(struct mddev *mddev, struct bio *bio);
 482        int (*run)(struct mddev *mddev);
 483        void (*free)(struct mddev *mddev, void *priv);
 484        void (*status)(struct seq_file *seq, struct mddev *mddev);
 485        /* error_handler must set ->faulty and clear ->in_sync
 486         * if appropriate, and should abort recovery if needed
 487         */
 488        void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
 489        int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
 490        int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
 491        int (*spare_active) (struct mddev *mddev);
 492        sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
 493        int (*resize) (struct mddev *mddev, sector_t sectors);
 494        sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
 495        int (*check_reshape) (struct mddev *mddev);
 496        int (*start_reshape) (struct mddev *mddev);
 497        void (*finish_reshape) (struct mddev *mddev);
 498        /* quiesce moves between quiescence states
 499         * 0 - fully active
 500         * 1 - no new requests allowed
 501         * others - reserved
 502         */
 503        void (*quiesce) (struct mddev *mddev, int state);
 504        /* takeover is used to transition an array from one
 505         * personality to another.  The new personality must be able
 506         * to handle the data in the current layout.
 507         * e.g. 2drive raid1 -> 2drive raid5
 508         *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 509         * If the takeover succeeds, a new 'private' structure is returned.
 510         * This needs to be installed and then ->run used to activate the
 511         * array.
 512         */
 513        void *(*takeover) (struct mddev *mddev);
 514        /* congested implements bdi.congested_fn().
 515         * Will not be called while array is 'suspended' */
 516        int (*congested)(struct mddev *mddev, int bits);
 517};
 518
 519struct md_sysfs_entry {
 520        struct attribute attr;
 521        ssize_t (*show)(struct mddev *, char *);
 522        ssize_t (*store)(struct mddev *, const char *, size_t);
 523};
 524extern struct attribute_group md_bitmap_group;
 525
 526static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
 527{
 528        if (sd)
 529                return sysfs_get_dirent(sd, name);
 530        return sd;
 531}
 532static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
 533{
 534        if (sd)
 535                sysfs_notify_dirent(sd);
 536}
 537
 538static inline char * mdname (struct mddev * mddev)
 539{
 540        return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 541}
 542
 543static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 544{
 545        char nm[20];
 546        if (!test_bit(Replacement, &rdev->flags) &&
 547            !test_bit(Journal, &rdev->flags) &&
 548            mddev->kobj.sd) {
 549                sprintf(nm, "rd%d", rdev->raid_disk);
 550                return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 551        } else
 552                return 0;
 553}
 554
 555static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 556{
 557        char nm[20];
 558        if (!test_bit(Replacement, &rdev->flags) &&
 559            !test_bit(Journal, &rdev->flags) &&
 560            mddev->kobj.sd) {
 561                sprintf(nm, "rd%d", rdev->raid_disk);
 562                sysfs_remove_link(&mddev->kobj, nm);
 563        }
 564}
 565
 566/*
 567 * iterates through some rdev ringlist. It's safe to remove the
 568 * current 'rdev'. Dont touch 'tmp' though.
 569 */
 570#define rdev_for_each_list(rdev, tmp, head)                             \
 571        list_for_each_entry_safe(rdev, tmp, head, same_set)
 572
 573/*
 574 * iterates through the 'same array disks' ringlist
 575 */
 576#define rdev_for_each(rdev, mddev)                              \
 577        list_for_each_entry(rdev, &((mddev)->disks), same_set)
 578
 579#define rdev_for_each_safe(rdev, tmp, mddev)                            \
 580        list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 581
 582#define rdev_for_each_rcu(rdev, mddev)                          \
 583        list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 584
 585struct md_thread {
 586        void                    (*run) (struct md_thread *thread);
 587        struct mddev            *mddev;
 588        wait_queue_head_t       wqueue;
 589        unsigned long           flags;
 590        struct task_struct      *tsk;
 591        unsigned long           timeout;
 592        void                    *private;
 593};
 594
 595#define THREAD_WAKEUP  0
 596
 597static inline void safe_put_page(struct page *p)
 598{
 599        if (p) put_page(p);
 600}
 601
 602extern int register_md_personality(struct md_personality *p);
 603extern int unregister_md_personality(struct md_personality *p);
 604extern int register_md_cluster_operations(struct md_cluster_operations *ops,
 605                struct module *module);
 606extern int unregister_md_cluster_operations(void);
 607extern int md_setup_cluster(struct mddev *mddev, int nodes);
 608extern void md_cluster_stop(struct mddev *mddev);
 609extern struct md_thread *md_register_thread(
 610        void (*run)(struct md_thread *thread),
 611        struct mddev *mddev,
 612        const char *name);
 613extern void md_unregister_thread(struct md_thread **threadp);
 614extern void md_wakeup_thread(struct md_thread *thread);
 615extern void md_check_recovery(struct mddev *mddev);
 616extern void md_reap_sync_thread(struct mddev *mddev);
 617extern void md_write_start(struct mddev *mddev, struct bio *bi);
 618extern void md_write_end(struct mddev *mddev);
 619extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 620extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 621extern void md_finish_reshape(struct mddev *mddev);
 622
 623extern int mddev_congested(struct mddev *mddev, int bits);
 624extern void md_flush_request(struct mddev *mddev, struct bio *bio);
 625extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 626                           sector_t sector, int size, struct page *page);
 627extern void md_super_wait(struct mddev *mddev);
 628extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 629                        struct page *page, int op, int op_flags,
 630                        bool metadata_op);
 631extern void md_do_sync(struct md_thread *thread);
 632extern void md_new_event(struct mddev *mddev);
 633extern int md_allow_write(struct mddev *mddev);
 634extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
 635extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
 636extern int md_check_no_bitmap(struct mddev *mddev);
 637extern int md_integrity_register(struct mddev *mddev);
 638extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
 639extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 640
 641extern void mddev_init(struct mddev *mddev);
 642extern int md_run(struct mddev *mddev);
 643extern void md_stop(struct mddev *mddev);
 644extern void md_stop_writes(struct mddev *mddev);
 645extern int md_rdev_init(struct md_rdev *rdev);
 646extern void md_rdev_clear(struct md_rdev *rdev);
 647
 648extern void mddev_suspend(struct mddev *mddev);
 649extern void mddev_resume(struct mddev *mddev);
 650extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 651                                   struct mddev *mddev);
 652extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 653                                   struct mddev *mddev);
 654
 655extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
 656extern void md_reload_sb(struct mddev *mddev, int raid_disk);
 657extern void md_update_sb(struct mddev *mddev, int force);
 658extern void md_kick_rdev_from_array(struct md_rdev * rdev);
 659struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
 660static inline int mddev_check_plugged(struct mddev *mddev)
 661{
 662        return !!blk_check_plugged(md_unplug, mddev,
 663                                   sizeof(struct blk_plug_cb));
 664}
 665
 666static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 667{
 668        int faulty = test_bit(Faulty, &rdev->flags);
 669        if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
 670                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 671                md_wakeup_thread(mddev->thread);
 672        }
 673}
 674
 675extern struct md_cluster_operations *md_cluster_ops;
 676static inline int mddev_is_clustered(struct mddev *mddev)
 677{
 678        return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
 679}
 680#endif /* _MD_MD_H */
 681