drivers/md/md.h

   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/kobject.h>
  20 #include <linux/list.h>
  21 #include <linux/mm.h>
  22 #include <linux/mutex.h>
  23 #include <linux/timer.h>
  24 #include <linux/wait.h>
  25 #include <linux/workqueue.h>
  26
  27 #define MaxSector (~(sector_t)0)
  28
  29 /* Bad block numbers are stored sorted in a single page.
  30  * 64bits is used for each block or extent.
  31  * 54 bits are sector number, 9 bits are extent size,
  32  * 1 bit is an 'acknowledged' flag.
  33  */
  34 #define MD_MAX_BADBLOCKS        (PAGE_SIZE/8)
  35
  36 /*
  37  * MD's 'extended' device
  38  */
  39 struct md_rdev {
  40         struct list_head same_set;      /* RAID devices within the same set */
  41
  42         sector_t sectors;               /* Device size (in 512bytes sectors) */
  43         struct mddev *mddev;            /* RAID array if running */
  44         int last_events;                /* IO event timestamp */
  45
  46         /*
  47          * If meta_bdev is non-NULL, it means that a separate device is
  48          * being used to store the metadata (superblock/bitmap) which
  49          * would otherwise be contained on the same device as the data (bdev).
  50          */
  51         struct block_device *meta_bdev;
  52         struct block_device *bdev;      /* block device handle */
  53
  54         struct page     *sb_page, *bb_page;
  55         int             sb_loaded;
  56         __u64           sb_events;
  57         sector_t        data_offset;    /* start of data in array */
  58         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  59         int             sb_size;        /* bytes in the superblock */
  60         int             preferred_minor;        /* autorun support */
  61
  62         struct kobject  kobj;
  63
  64         /* A device can be in one of three states based on two flags:
  65          * Not working:   faulty==1 in_sync==0
  66          * Fully working: faulty==0 in_sync==1
  67          * Working, but not
  68          * in sync with array
  69          *                faulty==0 in_sync==0
  70          *
  71          * It can never have faulty==1, in_sync==1
  72          * This reduces the burden of testing multiple flags in many cases
  73          */
  74
  75         unsigned long   flags;
  76 #define Faulty          1               /* device is known to have a fault */
  77 #define In_sync         2               /* device is in_sync with rest of array */
  78 #define WriteMostly     4               /* Avoid reading if at all possible */
  79 #define AutoDetected    7               /* added by auto-detect */
  80 #define Blocked         8               /* An error occurred but has not yet
  81                                          * been acknowledged by the metadata
  82                                          * handler, so don't allow writes
  83                                          * until it is cleared */
  84 #define WriteErrorSeen  9               /* A write error has been seen on this
  85                                          * device
  86                                          */
  87 #define FaultRecorded   10              /* Intermediate state for clearing
  88                                          * Blocked.  The Fault is/will-be
  89                                          * recorded in the metadata, but that
  90                                          * metadata hasn't been stored safely
  91                                          * on disk yet.
  92                                          */
  93 #define BlockedBadBlocks 11             /* A writer is blocked because they
  94                                          * found an unacknowledged bad-block.
  95                                          * This can safely be cleared at any
  96                                          * time, and the writer will re-check.
  97                                          * It may be set at any time, and at
  98                                          * worst the writer will timeout and
  99                                          * re-check.  So setting it as
 100                                          * accurately as possible is good, but
 101                                          * not absolutely critical.
 102                                          */
 103         wait_queue_head_t blocked_wait;
 104
 105         int desc_nr;                    /* descriptor index in the superblock */
 106         int raid_disk;                  /* role of device in array */
 107         int new_raid_disk;              /* role that the device will have in
 108                                          * the array after a level-change completes.
 109                                          */
 110         int saved_raid_disk;            /* role that device used to have in the
 111                                          * array and could again if we did a partial
 112                                          * resync from the bitmap
 113                                          */
 114         sector_t        recovery_offset;/* If this device has been partially
 115                                          * recovered, this is where we were
 116                                          * up to.
 117                                          */
 118
 119         atomic_t        nr_pending;     /* number of pending requests.
 120                                          * only maintained for arrays that
 121                                          * support hot removal
 122                                          */
 123         atomic_t        read_errors;    /* number of consecutive read errors that
 124                                          * we have tried to ignore.
 125                                          */
 126         struct timespec last_read_error;        /* monotonic time since our
 127                                                  * last read error
 128                                                  */
 129         atomic_t        corrected_errors; /* number of corrected read errors,
 130                                            * for reporting to userspace and storing
 131                                            * in superblock.
 132                                            */
 133         struct work_struct del_work;    /* used for delayed sysfs removal */
 134
 135         struct sysfs_dirent *sysfs_state; /* handle for 'state'
 136                                            * sysfs entry */
 137
 138         struct badblocks {
 139                 int     count;          /* count of bad blocks */
 140                 int     unacked_exist;  /* there probably are unacknowledged
 141                                          * bad blocks.  This is only cleared
 142                                          * when a read discovers none
 143                                          */
 144                 int     shift;          /* shift from sectors to block size
 145                                          * a -ve shift means badblocks are
 146                                          * disabled.*/
 147                 u64     *page;          /* badblock list */
 148                 int     changed;
 149                 seqlock_t lock;
 150
 151                 sector_t sector;
 152                 sector_t size;          /* in sectors */
 153         } badblocks;
 154 };
 155
 156 #define BB_LEN_MASK     (0x00000000000001FFULL)
 157 #define BB_OFFSET_MASK  (0x7FFFFFFFFFFFFE00ULL)
 158 #define BB_ACK_MASK     (0x8000000000000000ULL)
 159 #define BB_MAX_LEN      512
 160 #define BB_OFFSET(x)    (((x) & BB_OFFSET_MASK) >> 9)
 161 #define BB_LEN(x)       (((x) & BB_LEN_MASK) + 1)
 162 #define BB_ACK(x)       (!!((x) & BB_ACK_MASK))
 163 #define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
 164
 165 extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
 166                           sector_t *first_bad, int *bad_sectors);
 167 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
 168                               sector_t *first_bad, int *bad_sectors)
 169 {
 170         if (unlikely(rdev->badblocks.count)) {
 171                 int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
 172                                         sectors,
 173                                         first_bad, bad_sectors);
 174                 if (rv)
 175                         *first_bad -= rdev->data_offset;
 176                 return rv;
 177         }
 178         return 0;
 179 }
 180 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 181                               int acknowledged);
 182 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors);
 183 extern void md_ack_all_badblocks(struct badblocks *bb);
 184
 185 struct mddev {
 186         void                            *private;
 187         struct md_personality           *pers;
 188         dev_t                           unit;
 189         int                             md_minor;
 190         struct list_head                disks;
 191         unsigned long                   flags;
 192 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
 193 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 194 #define MD_CHANGE_PENDING 2     /* switch from 'clean' to 'active' in progress */
 195 #define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
 196
 197         int                             suspended;
 198         atomic_t                        active_io;
 199         int                             ro;
 200         int                             sysfs_active; /* set when sysfs deletes
 201                                                        * are happening, so run/
 202                                                        * takeover/stop are not safe
 203                                                        */
 204         int                             ready; /* See when safe to pass
 205                                                 * IO requests down */
 206         struct gendisk                  *gendisk;
 207
 208         struct kobject                  kobj;
 209         int                             hold_active;
 210 #define UNTIL_IOCTL     1
 211 #define UNTIL_STOP      2
 212
 213         /* Superblock information */
 214         int                             major_version,
 215                                         minor_version,
 216                                         patch_version;
 217         int                             persistent;
 218         int                             external;       /* metadata is
 219                                                          * managed externally */
 220         char                            metadata_type[17]; /* externally set*/
 221         int                             chunk_sectors;
 222         time_t                          ctime, utime;
 223         int                             level, layout;
 224         char                            clevel[16];
 225         int                             raid_disks;
 226         int                             max_disks;
 227         sector_t                        dev_sectors;    /* used size of
 228                                                          * component devices */
 229         sector_t                        array_sectors; /* exported array size */
 230         int                             external_size; /* size managed
 231                                                         * externally */
 232         __u64                           events;
 233         /* If the last 'event' was simply a clean->dirty transition, and
 234          * we didn't write it to the spares, then it is safe and simple
 235          * to just decrement the event count on a dirty->clean transition.
 236          * So we record that possibility here.
 237          */
 238         int                             can_decrease_events;
 239
 240         char                            uuid[16];
 241
 242         /* If the array is being reshaped, we need to record the
 243          * new shape and an indication of where we are up to.
 244          * This is written to the superblock.
 245          * If reshape_position is MaxSector, then no reshape is happening (yet).
 246          */
 247         sector_t                        reshape_position;
 248         int                             delta_disks, new_level, new_layout;
 249         int                             new_chunk_sectors;
 250
 251         atomic_t                        plug_cnt;       /* If device is expecting
 252                                                          * more bios soon.
 253                                                          */
 254         struct md_thread                *thread;        /* management thread */
 255         struct md_thread                *sync_thread;   /* doing resync or reconstruct */
 256         sector_t                        curr_resync;    /* last block scheduled */
 257         /* As resync requests can complete out of order, we cannot easily track
 258          * how much resync has been completed.  So we occasionally pause until
 259          * everything completes, then set curr_resync_completed to curr_resync.
 260          * As such it may be well behind the real resync mark, but it is a value
 261          * we are certain of.
 262          */
 263         sector_t                        curr_resync_completed;
 264         unsigned long                   resync_mark;    /* a recent timestamp */
 265         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 266         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 267
 268         sector_t                        resync_max_sectors; /* may be set by personality */
 269
 270         sector_t                        resync_mismatches; /* count of sectors where
 271                                                             * parity/replica mismatch found
 272                                                             */
 273
 274         /* allow user-space to request suspension of IO to regions of the array */
 275         sector_t                        suspend_lo;
 276         sector_t                        suspend_hi;
 277         /* if zero, use the system-wide default */
 278         int                             sync_speed_min;
 279         int                             sync_speed_max;
 280
 281         /* resync even though the same disks are shared among md-devices */
 282         int                             parallel_resync;
 283
 284         int                             ok_start_degraded;
 285         /* recovery/resync flags
 286          * NEEDED:   we might need to start a resync/recover
 287          * RUNNING:  a thread is running, or about to be started
 288          * SYNC:     actually doing a resync, not a recovery
 289          * RECOVER:  doing recovery, or need to try it.
 290          * INTR:     resync needs to be aborted for some reason
 291          * DONE:     thread is done and is waiting to be reaped
 292          * REQUEST:  user-space has requested a sync (used with SYNC)
 293          * CHECK:    user-space request for check-only, no repair
 294          * RESHAPE:  A reshape is happening
 295          *
 296          * If neither SYNC or RESHAPE are set, then it is a recovery.
 297          */
 298 #define MD_RECOVERY_RUNNING     0
 299 #define MD_RECOVERY_SYNC        1
 300 #define MD_RECOVERY_RECOVER     2
 301 #define MD_RECOVERY_INTR        3
 302 #define MD_RECOVERY_DONE        4
 303 #define MD_RECOVERY_NEEDED      5
 304 #define MD_RECOVERY_REQUESTED   6
 305 #define MD_RECOVERY_CHECK       7
 306 #define MD_RECOVERY_RESHAPE     8
 307 #define MD_RECOVERY_FROZEN      9
 308
 309         unsigned long                   recovery;
 310         /* If a RAID personality determines that recovery (of a particular
 311          * device) will fail due to a read error on the source device, it
 312          * takes a copy of this number and does not attempt recovery again
 313          * until this number changes.
 314          */
 315         int                             recovery_disabled;
 316
 317         int                             in_sync;        /* know to not need resync */
 318         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 319          * that we are never stopping an array while it is open.
 320          * 'reconfig_mutex' protects all other reconfiguration.
 321          * These locks are separate due to conflicting interactions
 322          * with bdev->bd_mutex.
 323          * Lock ordering is:
 324          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 325          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 326          */
 327         struct mutex                    open_mutex;
 328         struct mutex                    reconfig_mutex;
 329         atomic_t                        active;         /* general refcount */
 330         atomic_t                        openers;        /* number of active opens */
 331
 332         int                             changed;        /* True if we might need to
 333                                                          * reread partition info */
 334         int                             degraded;       /* whether md should consider
 335                                                          * adding a spare
 336                                                          */
 337
 338         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 339         wait_queue_head_t               recovery_wait;
 340         sector_t                        recovery_cp;
 341         sector_t                        resync_min;     /* user requested sync
 342                                                          * starts here */
 343         sector_t                        resync_max;     /* resync should pause
 344                                                          * when it gets here */
 345
 346         struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
 347                                                          * file in sysfs.
 348                                                          */
 349         struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
 350
 351         struct work_struct del_work;    /* used for delayed sysfs removal */
 352
 353         spinlock_t                      write_lock;
 354         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 355         atomic_t                        pending_writes; /* number of active superblock writes */
 356
 357         unsigned int                    safemode;       /* if set, update "clean" superblock
 358                                                          * when no writes pending.
 359                                                          */
 360         unsigned int                    safemode_delay;
 361         struct timer_list               safemode_timer;
 362         atomic_t                        writes_pending;
 363         struct request_queue            *queue; /* for plugging ... */
 364
 365         struct bitmap                   *bitmap; /* the bitmap for the device */
 366         struct {
 367                 struct file             *file; /* the bitmap file */
 368                 loff_t                  offset; /* offset from superblock of
 369                                                  * start of bitmap. May be
 370                                                  * negative, but not '0'
 371                                                  * For external metadata, offset
 372                                                  * from start of device.
 373                                                  */
 374                 loff_t                  default_offset; /* this is the offset to use when
 375                                                          * hot-adding a bitmap.  It should
 376                                                          * eventually be settable by sysfs.
 377                                                          */
 378                 struct mutex            mutex;
 379                 unsigned long           chunksize;
 380                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
 381                 unsigned long           max_write_behind; /* write-behind mode */
 382                 int                     external;
 383         } bitmap_info;
 384
 385         atomic_t                        max_corr_read_errors; /* max read retries */
 386         struct list_head                all_mddevs;
 387
 388         struct attribute_group          *to_remove;
 389
 390         struct bio_set                  *bio_set;
 391
 392         /* Generic flush handling.
 393          * The last to finish preflush schedules a worker to submit
 394          * the rest of the request (without the REQ_FLUSH flag).
 395          */
 396         struct bio *flush_bio;
 397         atomic_t flush_pending;
 398         struct work_struct flush_work;
 399         struct work_struct event_work;  /* used by dm to report failure event */
 400         void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 401 };
 402
 403
 404 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 405 {
 406         int faulty = test_bit(Faulty, &rdev->flags);
 407         if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
 408                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 409 }
 410
 411 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 412 {
 413         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 414 }
 415
 416 struct md_personality
 417 {
 418         char *name;
 419         int level;
 420         struct list_head list;
 421         struct module *owner;
 422         void (*make_request)(struct mddev *mddev, struct bio *bio);
 423         int (*run)(struct mddev *mddev);
 424         int (*stop)(struct mddev *mddev);
 425         void (*status)(struct seq_file *seq, struct mddev *mddev);
 426         /* error_handler must set ->faulty and clear ->in_sync
 427          * if appropriate, and should abort recovery if needed
 428          */
 429         void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
 430         int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
 431         int (*hot_remove_disk) (struct mddev *mddev, int number);
 432         int (*spare_active) (struct mddev *mddev);
 433         sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster);
 434         int (*resize) (struct mddev *mddev, sector_t sectors);
 435         sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
 436         int (*check_reshape) (struct mddev *mddev);
 437         int (*start_reshape) (struct mddev *mddev);
 438         void (*finish_reshape) (struct mddev *mddev);
 439         /* quiesce moves between quiescence states
 440          * 0 - fully active
 441          * 1 - no new requests allowed
 442          * others - reserved
 443          */
 444         void (*quiesce) (struct mddev *mddev, int state);
 445         /* takeover is used to transition an array from one
 446          * personality to another.  The new personality must be able
 447          * to handle the data in the current layout.
 448          * e.g. 2drive raid1 -> 2drive raid5
 449          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 450          * If the takeover succeeds, a new 'private' structure is returned.
 451          * This needs to be installed and then ->run used to activate the
 452          * array.
 453          */
 454         void *(*takeover) (struct mddev *mddev);
 455 };
 456
 457
 458 struct md_sysfs_entry {
 459         struct attribute attr;
 460         ssize_t (*show)(struct mddev *, char *);
 461         ssize_t (*store)(struct mddev *, const char *, size_t);
 462 };
 463 extern struct attribute_group md_bitmap_group;
 464
 465 static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
 466 {
 467         if (sd)
 468                 return sysfs_get_dirent(sd, NULL, name);
 469         return sd;
 470 }
 471 static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
 472 {
 473         if (sd)
 474                 sysfs_notify_dirent(sd);
 475 }
 476
 477 static inline char * mdname (struct mddev * mddev)
 478 {
 479         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 480 }
 481
 482 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 483 {
 484         char nm[20];
 485         sprintf(nm, "rd%d", rdev->raid_disk);
 486         return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 487 }
 488
 489 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 490 {
 491         char nm[20];
 492         sprintf(nm, "rd%d", rdev->raid_disk);
 493         sysfs_remove_link(&mddev->kobj, nm);
 494 }
 495
 496 /*
 497  * iterates through some rdev ringlist. It's safe to remove the
 498  * current 'rdev'. Dont touch 'tmp' though.
 499  */
 500 #define rdev_for_each_list(rdev, tmp, head)                             \
 501         list_for_each_entry_safe(rdev, tmp, head, same_set)
 502
 503 /*
 504  * iterates through the 'same array disks' ringlist
 505  */
 506 #define rdev_for_each(rdev, tmp, mddev)                         \
 507         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 508
 509 #define rdev_for_each_rcu(rdev, mddev)                          \
 510         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 511
 512 struct md_thread {
 513         void                    (*run) (struct mddev *mddev);
 514         struct mddev            *mddev;
 515         wait_queue_head_t       wqueue;
 516         unsigned long           flags;
 517         struct task_struct      *tsk;
 518         unsigned long           timeout;
 519 };
 520
 521 #define THREAD_WAKEUP  0
 522
 523 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 524 do {                                                                    \
 525         wait_queue_t __wait;                                            \
 526         init_waitqueue_entry(&__wait, current);                         \
 527                                                                         \
 528         add_wait_queue(&wq, &__wait);                                   \
 529         for (;;) {                                                      \
 530                 set_current_state(TASK_UNINTERRUPTIBLE);                \
 531                 if (condition)                                          \
 532                         break;                                          \
 533                 spin_unlock_irq(&lock);                                 \
 534                 cmd;                                                    \
 535                 schedule();                                             \
 536                 spin_lock_irq(&lock);                                   \
 537         }                                                               \
 538         current->state = TASK_RUNNING;                                  \
 539         remove_wait_queue(&wq, &__wait);                                \
 540 } while (0)
 541
 542 #define wait_event_lock_irq(wq, condition, lock, cmd)                   \
 543 do {                                                                    \
 544         if (condition)                                                  \
 545                 break;                                                  \
 546         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 547 } while (0)
 548
 549 static inline void safe_put_page(struct page *p)
 550 {
 551         if (p) put_page(p);
 552 }
 553
 554 extern int register_md_personality(struct md_personality *p);
 555 extern int unregister_md_personality(struct md_personality *p);
 556 extern struct md_thread *md_register_thread(
 557         void (*run)(struct mddev *mddev),
 558         struct mddev *mddev,
 559         const char *name);
 560 extern void md_unregister_thread(struct md_thread **threadp);
 561 extern void md_wakeup_thread(struct md_thread *thread);
 562 extern void md_check_recovery(struct mddev *mddev);
 563 extern void md_write_start(struct mddev *mddev, struct bio *bi);
 564 extern void md_write_end(struct mddev *mddev);
 565 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 566 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 567
 568 extern int mddev_congested(struct mddev *mddev, int bits);
 569 extern void md_flush_request(struct mddev *mddev, struct bio *bio);
 570 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 571                            sector_t sector, int size, struct page *page);
 572 extern void md_super_wait(struct mddev *mddev);
 573 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 574                         struct page *page, int rw, bool metadata_op);
 575 extern void md_do_sync(struct mddev *mddev);
 576 extern void md_new_event(struct mddev *mddev);
 577 extern int md_allow_write(struct mddev *mddev);
 578 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
 579 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
 580 extern int md_check_no_bitmap(struct mddev *mddev);
 581 extern int md_integrity_register(struct mddev *mddev);
 582 extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
 583 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 584 extern void restore_bitmap_write_access(struct file *file);
 585
 586 extern void mddev_init(struct mddev *mddev);
 587 extern int md_run(struct mddev *mddev);
 588 extern void md_stop(struct mddev *mddev);
 589 extern void md_stop_writes(struct mddev *mddev);
 590 extern int md_rdev_init(struct md_rdev *rdev);
 591
 592 extern void mddev_suspend(struct mddev *mddev);
 593 extern void mddev_resume(struct mddev *mddev);
 594 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 595                                    struct mddev *mddev);
 596 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 597                                    struct mddev *mddev);
 598 extern int mddev_check_plugged(struct mddev *mddev);
 599 extern void md_trim_bio(struct bio *bio, int offset, int size);
 600 #endif /* _MD_MD_H */