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/backing-dev.h>
  20 #include <linux/kobject.h>
  21 #include <linux/list.h>
  22 #include <linux/mm.h>
  23 #include <linux/mutex.h>
  24 #include <linux/timer.h>
  25 #include <linux/wait.h>
  26 #include <linux/workqueue.h>
  27 #include "md-cluster.h"
  28
  29 #define MaxSector (~(sector_t)0)
  30
  31 /* Bad block numbers are stored sorted in a single page.
  32  * 64bits is used for each block or extent.
  33  * 54 bits are sector number, 9 bits are extent size,
  34  * 1 bit is an 'acknowledged' flag.
  35  */
  36 #define MD_MAX_BADBLOCKS        (PAGE_SIZE/8)
  37
  38 /*
  39  * MD's 'extended' device
  40  */
  41 struct md_rdev {
  42         struct list_head same_set;      /* RAID devices within the same set */
  43
  44         sector_t sectors;               /* Device size (in 512bytes sectors) */
  45         struct mddev *mddev;            /* RAID array if running */
  46         int last_events;                /* IO event timestamp */
  47
  48         /*
  49          * If meta_bdev is non-NULL, it means that a separate device is
  50          * being used to store the metadata (superblock/bitmap) which
  51          * would otherwise be contained on the same device as the data (bdev).
  52          */
  53         struct block_device *meta_bdev;
  54         struct block_device *bdev;      /* block device handle */
  55
  56         struct page     *sb_page, *bb_page;
  57         int             sb_loaded;
  58         __u64           sb_events;
  59         sector_t        data_offset;    /* start of data in array */
  60         sector_t        new_data_offset;/* only relevant while reshaping */
  61         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  62         int             sb_size;        /* bytes in the superblock */
  63         int             preferred_minor;        /* autorun support */
  64
  65         struct kobject  kobj;
  66
  67         /* A device can be in one of three states based on two flags:
  68          * Not working:   faulty==1 in_sync==0
  69          * Fully working: faulty==0 in_sync==1
  70          * Working, but not
  71          * in sync with array
  72          *                faulty==0 in_sync==0
  73          *
  74          * It can never have faulty==1, in_sync==1
  75          * This reduces the burden of testing multiple flags in many cases
  76          */
  77
  78         unsigned long   flags;  /* bit set of 'enum flag_bits' bits. */
  79         wait_queue_head_t blocked_wait;
  80
  81         int desc_nr;                    /* descriptor index in the superblock */
  82         int raid_disk;                  /* role of device in array */
  83         int new_raid_disk;              /* role that the device will have in
  84                                          * the array after a level-change completes.
  85                                          */
  86         int saved_raid_disk;            /* role that device used to have in the
  87                                          * array and could again if we did a partial
  88                                          * resync from the bitmap
  89                                          */
  90         sector_t        recovery_offset;/* If this device has been partially
  91                                          * recovered, this is where we were
  92                                          * up to.
  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         struct timespec 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 {
 115                 int     count;          /* count of bad blocks */
 116                 int     unacked_exist;  /* there probably are unacknowledged
 117                                          * bad blocks.  This is only cleared
 118                                          * when a read discovers none
 119                                          */
 120                 int     shift;          /* shift from sectors to block size
 121                                          * a -ve shift means badblocks are
 122                                          * disabled.*/
 123                 u64     *page;          /* badblock list */
 124                 int     changed;
 125                 seqlock_t lock;
 126
 127                 sector_t sector;
 128                 sector_t size;          /* in sectors */
 129         } badblocks;
 130 };
 131 enum flag_bits {
 132         Faulty,                 /* device is known to have a fault */
 133         In_sync,                /* device is in_sync with rest of array */
 134         Bitmap_sync,            /* ..actually, not quite In_sync.  Need a
 135                                  * bitmap-based recovery to get fully in sync
 136                                  */
 137         Unmerged,               /* device is being added to array and should
 138                                  * be considerred for bvec_merge_fn but not
 139                                  * yet for actual IO
 140                                  */
 141         WriteMostly,            /* Avoid reading if at all possible */
 142         AutoDetected,           /* added by auto-detect */
 143         Blocked,                /* An error occurred but has not yet
 144                                  * been acknowledged by the metadata
 145                                  * handler, so don't allow writes
 146                                  * until it is cleared */
 147         WriteErrorSeen,         /* A write error has been seen on this
 148                                  * device
 149                                  */
 150         FaultRecorded,          /* Intermediate state for clearing
 151                                  * Blocked.  The Fault is/will-be
 152                                  * recorded in the metadata, but that
 153                                  * metadata hasn't been stored safely
 154                                  * on disk yet.
 155                                  */
 156         BlockedBadBlocks,       /* A writer is blocked because they
 157                                  * found an unacknowledged bad-block.
 158                                  * This can safely be cleared at any
 159                                  * time, and the writer will re-check.
 160                                  * It may be set at any time, and at
 161                                  * worst the writer will timeout and
 162                                  * re-check.  So setting it as
 163                                  * accurately as possible is good, but
 164                                  * not absolutely critical.
 165                                  */
 166         WantReplacement,        /* This device is a candidate to be
 167                                  * hot-replaced, either because it has
 168                                  * reported some faults, or because
 169                                  * of explicit request.
 170                                  */
 171         Replacement,            /* This device is a replacement for
 172                                  * a want_replacement device with same
 173                                  * raid_disk number.
 174                                  */
 175         Candidate,              /* For clustered environments only:
 176                                  * This device is seen locally but not
 177                                  * by the whole cluster
 178                                  */
 179 };
 180
 181 #define BB_LEN_MASK     (0x00000000000001FFULL)
 182 #define BB_OFFSET_MASK  (0x7FFFFFFFFFFFFE00ULL)
 183 #define BB_ACK_MASK     (0x8000000000000000ULL)
 184 #define BB_MAX_LEN      512
 185 #define BB_OFFSET(x)    (((x) & BB_OFFSET_MASK) >> 9)
 186 #define BB_LEN(x)       (((x) & BB_LEN_MASK) + 1)
 187 #define BB_ACK(x)       (!!((x) & BB_ACK_MASK))
 188 #define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
 189
 190 extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
 191                           sector_t *first_bad, int *bad_sectors);
 192 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
 193                               sector_t *first_bad, int *bad_sectors)
 194 {
 195         if (unlikely(rdev->badblocks.count)) {
 196                 int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
 197                                         sectors,
 198                                         first_bad, bad_sectors);
 199                 if (rv)
 200                         *first_bad -= rdev->data_offset;
 201                 return rv;
 202         }
 203         return 0;
 204 }
 205 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 206                               int is_new);
 207 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 208                                 int is_new);
 209 extern void md_ack_all_badblocks(struct badblocks *bb);
 210
 211 struct md_cluster_info;
 212
 213 struct mddev {
 214         void                            *private;
 215         struct md_personality           *pers;
 216         dev_t                           unit;
 217         int                             md_minor;
 218         struct list_head                disks;
 219         unsigned long                   flags;
 220 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
 221 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 222 #define MD_CHANGE_PENDING 2     /* switch from 'clean' to 'active' in progress */
 223 #define MD_UPDATE_SB_FLAGS (1 | 2 | 4)  /* If these are set, md_update_sb needed */
 224 #define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
 225 #define MD_STILL_CLOSED 4       /* If set, then array has not been opened since
 226                                  * md_ioctl checked on it.
 227                                  */
 228
 229         int                             suspended;
 230         atomic_t                        active_io;
 231         int                             ro;
 232         int                             sysfs_active; /* set when sysfs deletes
 233                                                        * are happening, so run/
 234                                                        * takeover/stop are not safe
 235                                                        */
 236         int                             ready; /* See when safe to pass
 237                                                 * IO requests down */
 238         struct gendisk                  *gendisk;
 239
 240         struct kobject                  kobj;
 241         int                             hold_active;
 242 #define UNTIL_IOCTL     1
 243 #define UNTIL_STOP      2
 244
 245         /* Superblock information */
 246         int                             major_version,
 247                                         minor_version,
 248                                         patch_version;
 249         int                             persistent;
 250         int                             external;       /* metadata is
 251                                                          * managed externally */
 252         char                            metadata_type[17]; /* externally set*/
 253         int                             chunk_sectors;
 254         time_t                          ctime, utime;
 255         int                             level, layout;
 256         char                            clevel[16];
 257         int                             raid_disks;
 258         int                             max_disks;
 259         sector_t                        dev_sectors;    /* used size of
 260                                                          * component devices */
 261         sector_t                        array_sectors; /* exported array size */
 262         int                             external_size; /* size managed
 263                                                         * externally */
 264         __u64                           events;
 265         /* If the last 'event' was simply a clean->dirty transition, and
 266          * we didn't write it to the spares, then it is safe and simple
 267          * to just decrement the event count on a dirty->clean transition.
 268          * So we record that possibility here.
 269          */
 270         int                             can_decrease_events;
 271
 272         char                            uuid[16];
 273
 274         /* If the array is being reshaped, we need to record the
 275          * new shape and an indication of where we are up to.
 276          * This is written to the superblock.
 277          * If reshape_position is MaxSector, then no reshape is happening (yet).
 278          */
 279         sector_t                        reshape_position;
 280         int                             delta_disks, new_level, new_layout;
 281         int                             new_chunk_sectors;
 282         int                             reshape_backwards;
 283
 284         struct md_thread                *thread;        /* management thread */
 285         struct md_thread                *sync_thread;   /* doing resync or reconstruct */
 286
 287         /* 'last_sync_action' is initialized to "none".  It is set when a
 288          * sync operation (i.e "data-check", "requested-resync", "resync",
 289          * "recovery", or "reshape") is started.  It holds this value even
 290          * when the sync thread is "frozen" (interrupted) or "idle" (stopped
 291          * or finished).  It is overwritten when a new sync operation is begun.
 292          */
 293         char                            *last_sync_action;
 294         sector_t                        curr_resync;    /* last block scheduled */
 295         /* As resync requests can complete out of order, we cannot easily track
 296          * how much resync has been completed.  So we occasionally pause until
 297          * everything completes, then set curr_resync_completed to curr_resync.
 298          * As such it may be well behind the real resync mark, but it is a value
 299          * we are certain of.
 300          */
 301         sector_t                        curr_resync_completed;
 302         unsigned long                   resync_mark;    /* a recent timestamp */
 303         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 304         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 305
 306         sector_t                        resync_max_sectors; /* may be set by personality */
 307
 308         atomic64_t                      resync_mismatches; /* count of sectors where
 309                                                             * parity/replica mismatch found
 310                                                             */
 311
 312         /* allow user-space to request suspension of IO to regions of the array */
 313         sector_t                        suspend_lo;
 314         sector_t                        suspend_hi;
 315         /* if zero, use the system-wide default */
 316         int                             sync_speed_min;
 317         int                             sync_speed_max;
 318
 319         /* resync even though the same disks are shared among md-devices */
 320         int                             parallel_resync;
 321
 322         int                             ok_start_degraded;
 323         /* recovery/resync flags
 324          * NEEDED:   we might need to start a resync/recover
 325          * RUNNING:  a thread is running, or about to be started
 326          * SYNC:     actually doing a resync, not a recovery
 327          * RECOVER:  doing recovery, or need to try it.
 328          * INTR:     resync needs to be aborted for some reason
 329          * DONE:     thread is done and is waiting to be reaped
 330          * REQUEST:  user-space has requested a sync (used with SYNC)
 331          * CHECK:    user-space request for check-only, no repair
 332          * RESHAPE:  A reshape is happening
 333          * ERROR:    sync-action interrupted because io-error
 334          *
 335          * If neither SYNC or RESHAPE are set, then it is a recovery.
 336          */
 337 #define MD_RECOVERY_RUNNING     0
 338 #define MD_RECOVERY_SYNC        1
 339 #define MD_RECOVERY_RECOVER     2
 340 #define MD_RECOVERY_INTR        3
 341 #define MD_RECOVERY_DONE        4
 342 #define MD_RECOVERY_NEEDED      5
 343 #define MD_RECOVERY_REQUESTED   6
 344 #define MD_RECOVERY_CHECK       7
 345 #define MD_RECOVERY_RESHAPE     8
 346 #define MD_RECOVERY_FROZEN      9
 347 #define MD_RECOVERY_ERROR       10
 348
 349         unsigned long                   recovery;
 350         /* If a RAID personality determines that recovery (of a particular
 351          * device) will fail due to a read error on the source device, it
 352          * takes a copy of this number and does not attempt recovery again
 353          * until this number changes.
 354          */
 355         int                             recovery_disabled;
 356
 357         int                             in_sync;        /* know to not need resync */
 358         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 359          * that we are never stopping an array while it is open.
 360          * 'reconfig_mutex' protects all other reconfiguration.
 361          * These locks are separate due to conflicting interactions
 362          * with bdev->bd_mutex.
 363          * Lock ordering is:
 364          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 365          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 366          */
 367         struct mutex                    open_mutex;
 368         struct mutex                    reconfig_mutex;
 369         atomic_t                        active;         /* general refcount */
 370         atomic_t                        openers;        /* number of active opens */
 371
 372         int                             changed;        /* True if we might need to
 373                                                          * reread partition info */
 374         int                             degraded;       /* whether md should consider
 375                                                          * adding a spare
 376                                                          */
 377         int                             merge_check_needed; /* at least one
 378                                                              * member device
 379                                                              * has a
 380                                                              * merge_bvec_fn */
 381
 382         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 383         wait_queue_head_t               recovery_wait;
 384         sector_t                        recovery_cp;
 385         sector_t                        resync_min;     /* user requested sync
 386                                                          * starts here */
 387         sector_t                        resync_max;     /* resync should pause
 388                                                          * when it gets here */
 389
 390         struct kernfs_node              *sysfs_state;   /* handle for 'array_state'
 391                                                          * file in sysfs.
 392                                                          */
 393         struct kernfs_node              *sysfs_action;  /* handle for 'sync_action' */
 394
 395         struct work_struct del_work;    /* used for delayed sysfs removal */
 396
 397         /* "lock" protects:
 398          *   flush_bio transition from NULL to !NULL
 399          *   rdev superblocks, events
 400          *   clearing MD_CHANGE_*
 401          *   in_sync - and related safemode and MD_CHANGE changes
 402          *   pers (also protected by reconfig_mutex and pending IO).
 403          *   clearing ->bitmap
 404          *   clearing ->bitmap_info.file
 405          *   changing ->resync_{min,max}
 406          *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
 407          */
 408         spinlock_t                      lock;
 409         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 410         atomic_t                        pending_writes; /* number of active superblock writes */
 411
 412         unsigned int                    safemode;       /* if set, update "clean" superblock
 413                                                          * when no writes pending.
 414                                                          */
 415         unsigned int                    safemode_delay;
 416         struct timer_list               safemode_timer;
 417         atomic_t                        writes_pending;
 418         struct request_queue            *queue; /* for plugging ... */
 419
 420         struct bitmap                   *bitmap; /* the bitmap for the device */
 421         struct {
 422                 struct file             *file; /* the bitmap file */
 423                 loff_t                  offset; /* offset from superblock of
 424                                                  * start of bitmap. May be
 425                                                  * negative, but not '0'
 426                                                  * For external metadata, offset
 427                                                  * from start of device.
 428                                                  */
 429                 unsigned long           space; /* space available at this offset */
 430                 loff_t                  default_offset; /* this is the offset to use when
 431                                                          * hot-adding a bitmap.  It should
 432                                                          * eventually be settable by sysfs.
 433                                                          */
 434                 unsigned long           default_space; /* space available at
 435                                                         * default offset */
 436                 struct mutex            mutex;
 437                 unsigned long           chunksize;
 438                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
 439                 unsigned long           max_write_behind; /* write-behind mode */
 440                 int                     external;
 441                 int                     nodes; /* Maximum number of nodes in the cluster */
 442                 char                    cluster_name[64]; /* Name of the cluster */
 443         } bitmap_info;
 444
 445         atomic_t                        max_corr_read_errors; /* max read retries */
 446         struct list_head                all_mddevs;
 447
 448         struct attribute_group          *to_remove;
 449
 450         struct bio_set                  *bio_set;
 451
 452         /* Generic flush handling.
 453          * The last to finish preflush schedules a worker to submit
 454          * the rest of the request (without the REQ_FLUSH flag).
 455          */
 456         struct bio *flush_bio;
 457         atomic_t flush_pending;
 458         struct work_struct flush_work;
 459         struct work_struct event_work;  /* used by dm to report failure event */
 460         void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 461         struct md_cluster_info          *cluster_info;
 462 };
 463
 464 static inline int __must_check mddev_lock(struct mddev *mddev)
 465 {
 466         return mutex_lock_interruptible(&mddev->reconfig_mutex);
 467 }
 468
 469 /* Sometimes we need to take the lock in a situation where
 470  * failure due to interrupts is not acceptable.
 471  */
 472 static inline void mddev_lock_nointr(struct mddev *mddev)
 473 {
 474         mutex_lock(&mddev->reconfig_mutex);
 475 }
 476
 477 static inline int mddev_is_locked(struct mddev *mddev)
 478 {
 479         return mutex_is_locked(&mddev->reconfig_mutex);
 480 }
 481
 482 static inline int mddev_trylock(struct mddev *mddev)
 483 {
 484         return mutex_trylock(&mddev->reconfig_mutex);
 485 }
 486 extern void mddev_unlock(struct mddev *mddev);
 487
 488 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 489 {
 490         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 491 }
 492
 493 struct md_personality
 494 {
 495         char *name;
 496         int level;
 497         struct list_head list;
 498         struct module *owner;
 499         void (*make_request)(struct mddev *mddev, struct bio *bio);
 500         int (*run)(struct mddev *mddev);
 501         void (*free)(struct mddev *mddev, void *priv);
 502         void (*status)(struct seq_file *seq, struct mddev *mddev);
 503         /* error_handler must set ->faulty and clear ->in_sync
 504          * if appropriate, and should abort recovery if needed
 505          */
 506         void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
 507         int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
 508         int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
 509         int (*spare_active) (struct mddev *mddev);
 510         sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
 511         int (*resize) (struct mddev *mddev, sector_t sectors);
 512         sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
 513         int (*check_reshape) (struct mddev *mddev);
 514         int (*start_reshape) (struct mddev *mddev);
 515         void (*finish_reshape) (struct mddev *mddev);
 516         /* quiesce moves between quiescence states
 517          * 0 - fully active
 518          * 1 - no new requests allowed
 519          * others - reserved
 520          */
 521         void (*quiesce) (struct mddev *mddev, int state);
 522         /* takeover is used to transition an array from one
 523          * personality to another.  The new personality must be able
 524          * to handle the data in the current layout.
 525          * e.g. 2drive raid1 -> 2drive raid5
 526          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 527          * If the takeover succeeds, a new 'private' structure is returned.
 528          * This needs to be installed and then ->run used to activate the
 529          * array.
 530          */
 531         void *(*takeover) (struct mddev *mddev);
 532         /* congested implements bdi.congested_fn().
 533          * Will not be called while array is 'suspended' */
 534         int (*congested)(struct mddev *mddev, int bits);
 535         /* mergeable_bvec is use to implement ->merge_bvec_fn */
 536         int (*mergeable_bvec)(struct mddev *mddev,
 537                               struct bvec_merge_data *bvm,
 538                               struct bio_vec *biovec);
 539 };
 540
 541 struct md_sysfs_entry {
 542         struct attribute attr;
 543         ssize_t (*show)(struct mddev *, char *);
 544         ssize_t (*store)(struct mddev *, const char *, size_t);
 545 };
 546 extern struct attribute_group md_bitmap_group;
 547
 548 static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
 549 {
 550         if (sd)
 551                 return sysfs_get_dirent(sd, name);
 552         return sd;
 553 }
 554 static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
 555 {
 556         if (sd)
 557                 sysfs_notify_dirent(sd);
 558 }
 559
 560 static inline char * mdname (struct mddev * mddev)
 561 {
 562         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 563 }
 564
 565 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 566 {
 567         char nm[20];
 568         if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
 569                 sprintf(nm, "rd%d", rdev->raid_disk);
 570                 return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 571         } else
 572                 return 0;
 573 }
 574
 575 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 576 {
 577         char nm[20];
 578         if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
 579                 sprintf(nm, "rd%d", rdev->raid_disk);
 580                 sysfs_remove_link(&mddev->kobj, nm);
 581         }
 582 }
 583
 584 /*
 585  * iterates through some rdev ringlist. It's safe to remove the
 586  * current 'rdev'. Dont touch 'tmp' though.
 587  */
 588 #define rdev_for_each_list(rdev, tmp, head)                             \
 589         list_for_each_entry_safe(rdev, tmp, head, same_set)
 590
 591 /*
 592  * iterates through the 'same array disks' ringlist
 593  */
 594 #define rdev_for_each(rdev, mddev)                              \
 595         list_for_each_entry(rdev, &((mddev)->disks), same_set)
 596
 597 #define rdev_for_each_safe(rdev, tmp, mddev)                            \
 598         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 599
 600 #define rdev_for_each_rcu(rdev, mddev)                          \
 601         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 602
 603 struct md_thread {
 604         void                    (*run) (struct md_thread *thread);
 605         struct mddev            *mddev;
 606         wait_queue_head_t       wqueue;
 607         unsigned long           flags;
 608         struct task_struct      *tsk;
 609         unsigned long           timeout;
 610         void                    *private;
 611 };
 612
 613 #define THREAD_WAKEUP  0
 614
 615 static inline void safe_put_page(struct page *p)
 616 {
 617         if (p) put_page(p);
 618 }
 619
 620 extern int register_md_personality(struct md_personality *p);
 621 extern int unregister_md_personality(struct md_personality *p);
 622 extern int register_md_cluster_operations(struct md_cluster_operations *ops,
 623                 struct module *module);
 624 extern int unregister_md_cluster_operations(void);
 625 extern int md_setup_cluster(struct mddev *mddev, int nodes);
 626 extern void md_cluster_stop(struct mddev *mddev);
 627 extern struct md_thread *md_register_thread(
 628         void (*run)(struct md_thread *thread),
 629         struct mddev *mddev,
 630         const char *name);
 631 extern void md_unregister_thread(struct md_thread **threadp);
 632 extern void md_wakeup_thread(struct md_thread *thread);
 633 extern void md_check_recovery(struct mddev *mddev);
 634 extern void md_reap_sync_thread(struct mddev *mddev);
 635 extern void md_write_start(struct mddev *mddev, struct bio *bi);
 636 extern void md_write_end(struct mddev *mddev);
 637 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 638 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 639 extern void md_finish_reshape(struct mddev *mddev);
 640
 641 extern int mddev_congested(struct mddev *mddev, int bits);
 642 extern void md_flush_request(struct mddev *mddev, struct bio *bio);
 643 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 644                            sector_t sector, int size, struct page *page);
 645 extern void md_super_wait(struct mddev *mddev);
 646 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 647                         struct page *page, int rw, bool metadata_op);
 648 extern void md_do_sync(struct md_thread *thread);
 649 extern void md_new_event(struct mddev *mddev);
 650 extern int md_allow_write(struct mddev *mddev);
 651 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
 652 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
 653 extern int md_check_no_bitmap(struct mddev *mddev);
 654 extern int md_integrity_register(struct mddev *mddev);
 655 extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
 656 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 657
 658 extern void mddev_init(struct mddev *mddev);
 659 extern int md_run(struct mddev *mddev);
 660 extern void md_stop(struct mddev *mddev);
 661 extern void md_stop_writes(struct mddev *mddev);
 662 extern int md_rdev_init(struct md_rdev *rdev);
 663 extern void md_rdev_clear(struct md_rdev *rdev);
 664
 665 extern void mddev_suspend(struct mddev *mddev);
 666 extern void mddev_resume(struct mddev *mddev);
 667 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 668                                    struct mddev *mddev);
 669 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 670                                    struct mddev *mddev);
 671
 672 extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
 673 extern void md_reload_sb(struct mddev *mddev);
 674 extern void md_update_sb(struct mddev *mddev, int force);
 675 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
 676 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
 677 static inline int mddev_check_plugged(struct mddev *mddev)
 678 {
 679         return !!blk_check_plugged(md_unplug, mddev,
 680                                    sizeof(struct blk_plug_cb));
 681 }
 682
 683 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 684 {
 685         int faulty = test_bit(Faulty, &rdev->flags);
 686         if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
 687                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 688                 md_wakeup_thread(mddev->thread);
 689         }
 690 }
 691
 692 extern struct md_cluster_operations *md_cluster_ops;
 693 static inline int mddev_is_clustered(struct mddev *mddev)
 694 {
 695         return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
 696 }
 697 #endif /* _MD_MD_H */