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/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  * These flags should really be called "NO_RETRY" rather than
  34  * "FAILFAST" because they don't make any promise about time lapse,
  35  * only about the number of retries, which will be zero.
  36  * REQ_FAILFAST_DRIVER is not included because
  37  * Commit: 4a27446f3e39 ("[SCSI] modify scsi to handle new fail fast flags.")
  38  * seems to suggest that the errors it avoids retrying should usually
  39  * be retried.
  40  */
  41 #define MD_FAILFAST     (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)
  42 /*
  43  * MD's 'extended' device
  44  */
  45 struct md_rdev {
  46         struct list_head same_set;      /* RAID devices within the same set */
  47
  48         sector_t sectors;               /* Device size (in 512bytes sectors) */
  49         struct mddev *mddev;            /* RAID array if running */
  50         int last_events;                /* IO event timestamp */
  51
  52         /*
  53          * If meta_bdev is non-NULL, it means that a separate device is
  54          * being used to store the metadata (superblock/bitmap) which
  55          * would otherwise be contained on the same device as the data (bdev).
  56          */
  57         struct block_device *meta_bdev;
  58         struct block_device *bdev;      /* block device handle */
  59
  60         struct page     *sb_page, *bb_page;
  61         int             sb_loaded;
  62         __u64           sb_events;
  63         sector_t        data_offset;    /* start of data in array */
  64         sector_t        new_data_offset;/* only relevant while reshaping */
  65         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  66         int             sb_size;        /* bytes in the superblock */
  67         int             preferred_minor;        /* autorun support */
  68
  69         struct kobject  kobj;
  70
  71         /* A device can be in one of three states based on two flags:
  72          * Not working:   faulty==1 in_sync==0
  73          * Fully working: faulty==0 in_sync==1
  74          * Working, but not
  75          * in sync with array
  76          *                faulty==0 in_sync==0
  77          *
  78          * It can never have faulty==1, in_sync==1
  79          * This reduces the burden of testing multiple flags in many cases
  80          */
  81
  82         unsigned long   flags;  /* bit set of 'enum flag_bits' bits. */
  83         wait_queue_head_t blocked_wait;
  84
  85         int desc_nr;                    /* descriptor index in the superblock */
  86         int raid_disk;                  /* role of device in array */
  87         int new_raid_disk;              /* role that the device will have in
  88                                          * the array after a level-change completes.
  89                                          */
  90         int saved_raid_disk;            /* role that device used to have in the
  91                                          * array and could again if we did a partial
  92                                          * resync from the bitmap
  93                                          */
  94         union {
  95                 sector_t recovery_offset;/* If this device has been partially
  96                                          * recovered, this is where we were
  97                                          * up to.
  98                                          */
  99                 sector_t journal_tail;  /* If this device is a journal device,
 100                                          * this is the journal tail (journal
 101                                          * recovery start point)
 102                                          */
 103         };
 104
 105         atomic_t        nr_pending;     /* number of pending requests.
 106                                          * only maintained for arrays that
 107                                          * support hot removal
 108                                          */
 109         atomic_t        read_errors;    /* number of consecutive read errors that
 110                                          * we have tried to ignore.
 111                                          */
 112         time64_t        last_read_error;        /* monotonic time since our
 113                                                  * last read error
 114                                                  */
 115         atomic_t        corrected_errors; /* number of corrected read errors,
 116                                            * for reporting to userspace and storing
 117                                            * in superblock.
 118                                            */
 119         struct work_struct del_work;    /* used for delayed sysfs removal */
 120
 121         struct kernfs_node *sysfs_state; /* handle for 'state'
 122                                            * sysfs entry */
 123
 124         struct badblocks badblocks;
 125 };
 126 enum flag_bits {
 127         Faulty,                 /* device is known to have a fault */
 128         In_sync,                /* device is in_sync with rest of array */
 129         Bitmap_sync,            /* ..actually, not quite In_sync.  Need a
 130                                  * bitmap-based recovery to get fully in sync
 131                                  */
 132         WriteMostly,            /* Avoid reading if at all possible */
 133         AutoDetected,           /* added by auto-detect */
 134         Blocked,                /* An error occurred but has not yet
 135                                  * been acknowledged by the metadata
 136                                  * handler, so don't allow writes
 137                                  * until it is cleared */
 138         WriteErrorSeen,         /* A write error has been seen on this
 139                                  * device
 140                                  */
 141         FaultRecorded,          /* Intermediate state for clearing
 142                                  * Blocked.  The Fault is/will-be
 143                                  * recorded in the metadata, but that
 144                                  * metadata hasn't been stored safely
 145                                  * on disk yet.
 146                                  */
 147         BlockedBadBlocks,       /* A writer is blocked because they
 148                                  * found an unacknowledged bad-block.
 149                                  * This can safely be cleared at any
 150                                  * time, and the writer will re-check.
 151                                  * It may be set at any time, and at
 152                                  * worst the writer will timeout and
 153                                  * re-check.  So setting it as
 154                                  * accurately as possible is good, but
 155                                  * not absolutely critical.
 156                                  */
 157         WantReplacement,        /* This device is a candidate to be
 158                                  * hot-replaced, either because it has
 159                                  * reported some faults, or because
 160                                  * of explicit request.
 161                                  */
 162         Replacement,            /* This device is a replacement for
 163                                  * a want_replacement device with same
 164                                  * raid_disk number.
 165                                  */
 166         Candidate,              /* For clustered environments only:
 167                                  * This device is seen locally but not
 168                                  * by the whole cluster
 169                                  */
 170         Journal,                /* This device is used as journal for
 171                                  * raid-5/6.
 172                                  * Usually, this device should be faster
 173                                  * than other devices in the array
 174                                  */
 175         ClusterRemove,
 176         RemoveSynchronized,     /* synchronize_rcu() was called after
 177                                  * this device was known to be faulty,
 178                                  * so it is safe to remove without
 179                                  * another synchronize_rcu() call.
 180                                  */
 181         ExternalBbl,            /* External metadata provides bad
 182                                  * block management for a disk
 183                                  */
 184         FailFast,               /* Minimal retries should be attempted on
 185                                  * this device, so use REQ_FAILFAST_DEV.
 186                                  * Also don't try to repair failed reads.
 187                                  * It is expects that no bad block log
 188                                  * is present.
 189                                  */
 190         LastDev,                /* Seems to be the last working dev as
 191                                  * it didn't fail, so don't use FailFast
 192                                  * any more for metadata
 193                                  */
 194 };
 195
 196 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
 197                               sector_t *first_bad, int *bad_sectors)
 198 {
 199         if (unlikely(rdev->badblocks.count)) {
 200                 int rv = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
 201                                         sectors,
 202                                         first_bad, bad_sectors);
 203                 if (rv)
 204                         *first_bad -= rdev->data_offset;
 205                 return rv;
 206         }
 207         return 0;
 208 }
 209 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 210                               int is_new);
 211 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 212                                 int is_new);
 213 struct md_cluster_info;
 214
 215 enum mddev_flags {
 216         MD_ARRAY_FIRST_USE,     /* First use of array, needs initialization */
 217         MD_CLOSING,             /* If set, we are closing the array, do not open
 218                                  * it then */
 219         MD_JOURNAL_CLEAN,       /* A raid with journal is already clean */
 220         MD_HAS_JOURNAL,         /* The raid array has journal feature set */
 221         MD_RELOAD_SB,           /* Reload the superblock because another node
 222                                  * updated it.
 223                                  */
 224         MD_CLUSTER_RESYNC_LOCKED, /* cluster raid only, which means node
 225                                    * already took resync lock, need to
 226                                    * release the lock */
 227         MD_FAILFAST_SUPPORTED,  /* Using MD_FAILFAST on metadata writes is
 228                                  * supported as calls to md_error() will
 229                                  * never cause the array to become failed.
 230                                  */
 231 };
 232
 233 enum mddev_sb_flags {
 234         MD_SB_CHANGE_DEVS,              /* Some device status has changed */
 235         MD_SB_CHANGE_CLEAN,     /* transition to or from 'clean' */
 236         MD_SB_CHANGE_PENDING,   /* switch from 'clean' to 'active' in progress */
 237         MD_SB_NEED_REWRITE,     /* metadata write needs to be repeated */
 238 };
 239
 240 struct mddev {
 241         void                            *private;
 242         struct md_personality           *pers;
 243         dev_t                           unit;
 244         int                             md_minor;
 245         struct list_head                disks;
 246         unsigned long                   flags;
 247         unsigned long                   sb_flags;
 248
 249         int                             suspended;
 250         atomic_t                        active_io;
 251         int                             ro;
 252         int                             sysfs_active; /* set when sysfs deletes
 253                                                        * are happening, so run/
 254                                                        * takeover/stop are not safe
 255                                                        */
 256         struct gendisk                  *gendisk;
 257
 258         struct kobject                  kobj;
 259         int                             hold_active;
 260 #define UNTIL_IOCTL     1
 261 #define UNTIL_STOP      2
 262
 263         /* Superblock information */
 264         int                             major_version,
 265                                         minor_version,
 266                                         patch_version;
 267         int                             persistent;
 268         int                             external;       /* metadata is
 269                                                          * managed externally */
 270         char                            metadata_type[17]; /* externally set*/
 271         int                             chunk_sectors;
 272         time64_t                        ctime, utime;
 273         int                             level, layout;
 274         char                            clevel[16];
 275         int                             raid_disks;
 276         int                             max_disks;
 277         sector_t                        dev_sectors;    /* used size of
 278                                                          * component devices */
 279         sector_t                        array_sectors; /* exported array size */
 280         int                             external_size; /* size managed
 281                                                         * externally */
 282         __u64                           events;
 283         /* If the last 'event' was simply a clean->dirty transition, and
 284          * we didn't write it to the spares, then it is safe and simple
 285          * to just decrement the event count on a dirty->clean transition.
 286          * So we record that possibility here.
 287          */
 288         int                             can_decrease_events;
 289
 290         char                            uuid[16];
 291
 292         /* If the array is being reshaped, we need to record the
 293          * new shape and an indication of where we are up to.
 294          * This is written to the superblock.
 295          * If reshape_position is MaxSector, then no reshape is happening (yet).
 296          */
 297         sector_t                        reshape_position;
 298         int                             delta_disks, new_level, new_layout;
 299         int                             new_chunk_sectors;
 300         int                             reshape_backwards;
 301
 302         struct md_thread                *thread;        /* management thread */
 303         struct md_thread                *sync_thread;   /* doing resync or reconstruct */
 304
 305         /* 'last_sync_action' is initialized to "none".  It is set when a
 306          * sync operation (i.e "data-check", "requested-resync", "resync",
 307          * "recovery", or "reshape") is started.  It holds this value even
 308          * when the sync thread is "frozen" (interrupted) or "idle" (stopped
 309          * or finished).  It is overwritten when a new sync operation is begun.
 310          */
 311         char                            *last_sync_action;
 312         sector_t                        curr_resync;    /* last block scheduled */
 313         /* As resync requests can complete out of order, we cannot easily track
 314          * how much resync has been completed.  So we occasionally pause until
 315          * everything completes, then set curr_resync_completed to curr_resync.
 316          * As such it may be well behind the real resync mark, but it is a value
 317          * we are certain of.
 318          */
 319         sector_t                        curr_resync_completed;
 320         unsigned long                   resync_mark;    /* a recent timestamp */
 321         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 322         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 323
 324         sector_t                        resync_max_sectors; /* may be set by personality */
 325
 326         atomic64_t                      resync_mismatches; /* count of sectors where
 327                                                             * parity/replica mismatch found
 328                                                             */
 329
 330         /* allow user-space to request suspension of IO to regions of the array */
 331         sector_t                        suspend_lo;
 332         sector_t                        suspend_hi;
 333         /* if zero, use the system-wide default */
 334         int                             sync_speed_min;
 335         int                             sync_speed_max;
 336
 337         /* resync even though the same disks are shared among md-devices */
 338         int                             parallel_resync;
 339
 340         int                             ok_start_degraded;
 341
 342         unsigned long                   recovery;
 343         /* If a RAID personality determines that recovery (of a particular
 344          * device) will fail due to a read error on the source device, it
 345          * takes a copy of this number and does not attempt recovery again
 346          * until this number changes.
 347          */
 348         int                             recovery_disabled;
 349
 350         int                             in_sync;        /* know to not need resync */
 351         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 352          * that we are never stopping an array while it is open.
 353          * 'reconfig_mutex' protects all other reconfiguration.
 354          * These locks are separate due to conflicting interactions
 355          * with bdev->bd_mutex.
 356          * Lock ordering is:
 357          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 358          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 359          */
 360         struct mutex                    open_mutex;
 361         struct mutex                    reconfig_mutex;
 362         atomic_t                        active;         /* general refcount */
 363         atomic_t                        openers;        /* number of active opens */
 364
 365         int                             changed;        /* True if we might need to
 366                                                          * reread partition info */
 367         int                             degraded;       /* whether md should consider
 368                                                          * adding a spare
 369                                                          */
 370
 371         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 372         wait_queue_head_t               recovery_wait;
 373         sector_t                        recovery_cp;
 374         sector_t                        resync_min;     /* user requested sync
 375                                                          * starts here */
 376         sector_t                        resync_max;     /* resync should pause
 377                                                          * when it gets here */
 378
 379         struct kernfs_node              *sysfs_state;   /* handle for 'array_state'
 380                                                          * file in sysfs.
 381                                                          */
 382         struct kernfs_node              *sysfs_action;  /* handle for 'sync_action' */
 383
 384         struct work_struct del_work;    /* used for delayed sysfs removal */
 385
 386         /* "lock" protects:
 387          *   flush_bio transition from NULL to !NULL
 388          *   rdev superblocks, events
 389          *   clearing MD_CHANGE_*
 390          *   in_sync - and related safemode and MD_CHANGE changes
 391          *   pers (also protected by reconfig_mutex and pending IO).
 392          *   clearing ->bitmap
 393          *   clearing ->bitmap_info.file
 394          *   changing ->resync_{min,max}
 395          *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
 396          */
 397         spinlock_t                      lock;
 398         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 399         atomic_t                        pending_writes; /* number of active superblock writes */
 400
 401         unsigned int                    safemode;       /* if set, update "clean" superblock
 402                                                          * when no writes pending.
 403                                                          */
 404         unsigned int                    safemode_delay;
 405         struct timer_list               safemode_timer;
 406         atomic_t                        writes_pending;
 407         struct request_queue            *queue; /* for plugging ... */
 408
 409         struct bitmap                   *bitmap; /* the bitmap for the device */
 410         struct {
 411                 struct file             *file; /* the bitmap file */
 412                 loff_t                  offset; /* offset from superblock of
 413                                                  * start of bitmap. May be
 414                                                  * negative, but not '0'
 415                                                  * For external metadata, offset
 416                                                  * from start of device.
 417                                                  */
 418                 unsigned long           space; /* space available at this offset */
 419                 loff_t                  default_offset; /* this is the offset to use when
 420                                                          * hot-adding a bitmap.  It should
 421                                                          * eventually be settable by sysfs.
 422                                                          */
 423                 unsigned long           default_space; /* space available at
 424                                                         * default offset */
 425                 struct mutex            mutex;
 426                 unsigned long           chunksize;
 427                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
 428                 unsigned long           max_write_behind; /* write-behind mode */
 429                 int                     external;
 430                 int                     nodes; /* Maximum number of nodes in the cluster */
 431                 char                    cluster_name[64]; /* Name of the cluster */
 432         } bitmap_info;
 433
 434         atomic_t                        max_corr_read_errors; /* max read retries */
 435         struct list_head                all_mddevs;
 436
 437         struct attribute_group          *to_remove;
 438
 439         struct bio_set                  *bio_set;
 440
 441         /* Generic flush handling.
 442          * The last to finish preflush schedules a worker to submit
 443          * the rest of the request (without the REQ_PREFLUSH flag).
 444          */
 445         struct bio *flush_bio;
 446         atomic_t flush_pending;
 447         struct work_struct flush_work;
 448         struct work_struct event_work;  /* used by dm to report failure event */
 449         void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 450         struct md_cluster_info          *cluster_info;
 451         unsigned int                    good_device_nr; /* good device num within cluster raid */
 452 };
 453
 454 enum recovery_flags {
 455         /*
 456          * If neither SYNC or RESHAPE are set, then it is a recovery.
 457          */
 458         MD_RECOVERY_RUNNING,    /* a thread is running, or about to be started */
 459         MD_RECOVERY_SYNC,       /* actually doing a resync, not a recovery */
 460         MD_RECOVERY_RECOVER,    /* doing recovery, or need to try it. */
 461         MD_RECOVERY_INTR,       /* resync needs to be aborted for some reason */
 462         MD_RECOVERY_DONE,       /* thread is done and is waiting to be reaped */
 463         MD_RECOVERY_NEEDED,     /* we might need to start a resync/recover */
 464         MD_RECOVERY_REQUESTED,  /* user-space has requested a sync (used with SYNC) */
 465         MD_RECOVERY_CHECK,      /* user-space request for check-only, no repair */
 466         MD_RECOVERY_RESHAPE,    /* A reshape is happening */
 467         MD_RECOVERY_FROZEN,     /* User request to abort, and not restart, any action */
 468         MD_RECOVERY_ERROR,      /* sync-action interrupted because io-error */
 469 };
 470
 471 static inline int __must_check mddev_lock(struct mddev *mddev)
 472 {
 473         return mutex_lock_interruptible(&mddev->reconfig_mutex);
 474 }
 475
 476 /* Sometimes we need to take the lock in a situation where
 477  * failure due to interrupts is not acceptable.
 478  */
 479 static inline void mddev_lock_nointr(struct mddev *mddev)
 480 {
 481         mutex_lock(&mddev->reconfig_mutex);
 482 }
 483
 484 static inline int mddev_is_locked(struct mddev *mddev)
 485 {
 486         return mutex_is_locked(&mddev->reconfig_mutex);
 487 }
 488
 489 static inline int mddev_trylock(struct mddev *mddev)
 490 {
 491         return mutex_trylock(&mddev->reconfig_mutex);
 492 }
 493 extern void mddev_unlock(struct mddev *mddev);
 494
 495 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 496 {
 497         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 498 }
 499
 500 struct md_personality
 501 {
 502         char *name;
 503         int level;
 504         struct list_head list;
 505         struct module *owner;
 506         void (*make_request)(struct mddev *mddev, struct bio *bio);
 507         int (*run)(struct mddev *mddev);
 508         void (*free)(struct mddev *mddev, void *priv);
 509         void (*status)(struct seq_file *seq, struct mddev *mddev);
 510         /* error_handler must set ->faulty and clear ->in_sync
 511          * if appropriate, and should abort recovery if needed
 512          */
 513         void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
 514         int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
 515         int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
 516         int (*spare_active) (struct mddev *mddev);
 517         sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
 518         int (*resize) (struct mddev *mddev, sector_t sectors);
 519         sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
 520         int (*check_reshape) (struct mddev *mddev);
 521         int (*start_reshape) (struct mddev *mddev);
 522         void (*finish_reshape) (struct mddev *mddev);
 523         /* quiesce moves between quiescence states
 524          * 0 - fully active
 525          * 1 - no new requests allowed
 526          * others - reserved
 527          */
 528         void (*quiesce) (struct mddev *mddev, int state);
 529         /* takeover is used to transition an array from one
 530          * personality to another.  The new personality must be able
 531          * to handle the data in the current layout.
 532          * e.g. 2drive raid1 -> 2drive raid5
 533          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 534          * If the takeover succeeds, a new 'private' structure is returned.
 535          * This needs to be installed and then ->run used to activate the
 536          * array.
 537          */
 538         void *(*takeover) (struct mddev *mddev);
 539         /* congested implements bdi.congested_fn().
 540          * Will not be called while array is 'suspended' */
 541         int (*congested)(struct mddev *mddev, int bits);
 542 };
 543
 544 struct md_sysfs_entry {
 545         struct attribute attr;
 546         ssize_t (*show)(struct mddev *, char *);
 547         ssize_t (*store)(struct mddev *, const char *, size_t);
 548 };
 549 extern struct attribute_group md_bitmap_group;
 550
 551 static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
 552 {
 553         if (sd)
 554                 return sysfs_get_dirent(sd, name);
 555         return sd;
 556 }
 557 static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
 558 {
 559         if (sd)
 560                 sysfs_notify_dirent(sd);
 561 }
 562
 563 static inline char * mdname (struct mddev * mddev)
 564 {
 565         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 566 }
 567
 568 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 569 {
 570         char nm[20];
 571         if (!test_bit(Replacement, &rdev->flags) &&
 572             !test_bit(Journal, &rdev->flags) &&
 573             mddev->kobj.sd) {
 574                 sprintf(nm, "rd%d", rdev->raid_disk);
 575                 return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 576         } else
 577                 return 0;
 578 }
 579
 580 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 581 {
 582         char nm[20];
 583         if (!test_bit(Replacement, &rdev->flags) &&
 584             !test_bit(Journal, &rdev->flags) &&
 585             mddev->kobj.sd) {
 586                 sprintf(nm, "rd%d", rdev->raid_disk);
 587                 sysfs_remove_link(&mddev->kobj, nm);
 588         }
 589 }
 590
 591 /*
 592  * iterates through some rdev ringlist. It's safe to remove the
 593  * current 'rdev'. Dont touch 'tmp' though.
 594  */
 595 #define rdev_for_each_list(rdev, tmp, head)                             \
 596         list_for_each_entry_safe(rdev, tmp, head, same_set)
 597
 598 /*
 599  * iterates through the 'same array disks' ringlist
 600  */
 601 #define rdev_for_each(rdev, mddev)                              \
 602         list_for_each_entry(rdev, &((mddev)->disks), same_set)
 603
 604 #define rdev_for_each_safe(rdev, tmp, mddev)                            \
 605         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 606
 607 #define rdev_for_each_rcu(rdev, mddev)                          \
 608         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 609
 610 struct md_thread {
 611         void                    (*run) (struct md_thread *thread);
 612         struct mddev            *mddev;
 613         wait_queue_head_t       wqueue;
 614         unsigned long           flags;
 615         struct task_struct      *tsk;
 616         unsigned long           timeout;
 617         void                    *private;
 618 };
 619
 620 #define THREAD_WAKEUP  0
 621
 622 static inline void safe_put_page(struct page *p)
 623 {
 624         if (p) put_page(p);
 625 }
 626
 627 extern int register_md_personality(struct md_personality *p);
 628 extern int unregister_md_personality(struct md_personality *p);
 629 extern int register_md_cluster_operations(struct md_cluster_operations *ops,
 630                 struct module *module);
 631 extern int unregister_md_cluster_operations(void);
 632 extern int md_setup_cluster(struct mddev *mddev, int nodes);
 633 extern void md_cluster_stop(struct mddev *mddev);
 634 extern struct md_thread *md_register_thread(
 635         void (*run)(struct md_thread *thread),
 636         struct mddev *mddev,
 637         const char *name);
 638 extern void md_unregister_thread(struct md_thread **threadp);
 639 extern void md_wakeup_thread(struct md_thread *thread);
 640 extern void md_check_recovery(struct mddev *mddev);
 641 extern void md_reap_sync_thread(struct mddev *mddev);
 642 extern void md_write_start(struct mddev *mddev, struct bio *bi);
 643 extern void md_write_end(struct mddev *mddev);
 644 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 645 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 646 extern void md_finish_reshape(struct mddev *mddev);
 647
 648 extern int mddev_congested(struct mddev *mddev, int bits);
 649 extern void md_flush_request(struct mddev *mddev, struct bio *bio);
 650 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 651                            sector_t sector, int size, struct page *page);
 652 extern int md_super_wait(struct mddev *mddev);
 653 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 654                         struct page *page, int op, int op_flags,
 655                         bool metadata_op);
 656 extern void md_do_sync(struct md_thread *thread);
 657 extern void md_new_event(struct mddev *mddev);
 658 extern int md_allow_write(struct mddev *mddev);
 659 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
 660 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
 661 extern int md_check_no_bitmap(struct mddev *mddev);
 662 extern int md_integrity_register(struct mddev *mddev);
 663 extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
 664 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 665
 666 extern void mddev_init(struct mddev *mddev);
 667 extern int md_run(struct mddev *mddev);
 668 extern void md_stop(struct mddev *mddev);
 669 extern void md_stop_writes(struct mddev *mddev);
 670 extern int md_rdev_init(struct md_rdev *rdev);
 671 extern void md_rdev_clear(struct md_rdev *rdev);
 672
 673 extern void mddev_suspend(struct mddev *mddev);
 674 extern void mddev_resume(struct mddev *mddev);
 675 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 676                                    struct mddev *mddev);
 677 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 678                                    struct mddev *mddev);
 679
 680 extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
 681 extern void md_reload_sb(struct mddev *mddev, int raid_disk);
 682 extern void md_update_sb(struct mddev *mddev, int force);
 683 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
 684 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
 685 static inline int mddev_check_plugged(struct mddev *mddev)
 686 {
 687         return !!blk_check_plugged(md_unplug, mddev,
 688                                    sizeof(struct blk_plug_cb));
 689 }
 690
 691 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 692 {
 693         int faulty = test_bit(Faulty, &rdev->flags);
 694         if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
 695                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 696                 md_wakeup_thread(mddev->thread);
 697         }
 698 }
 699
 700 extern struct md_cluster_operations *md_cluster_ops;
 701 static inline int mddev_is_clustered(struct mddev *mddev)
 702 {
 703         return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
 704 }
 705 #endif /* _MD_MD_H */