drivers/md/md.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3    md.h : kernel internal structure of the Linux MD driver
   4           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
   5
   6 */
   7
   8 #ifndef _MD_MD_H
   9 #define _MD_MD_H
  10
  11 #include <linux/blkdev.h>
  12 #include <linux/backing-dev.h>
  13 #include <linux/badblocks.h>
  14 #include <linux/kobject.h>
  15 #include <linux/list.h>
  16 #include <linux/mm.h>
  17 #include <linux/mutex.h>
  18 #include <linux/timer.h>
  19 #include <linux/wait.h>
  20 #include <linux/workqueue.h>
  21 #include "md-cluster.h"
  22
  23 #define MaxSector (~(sector_t)0)
  24
  25 /*
  26  * These flags should really be called "NO_RETRY" rather than
  27  * "FAILFAST" because they don't make any promise about time lapse,
  28  * only about the number of retries, which will be zero.
  29  * REQ_FAILFAST_DRIVER is not included because
  30  * Commit: 4a27446f3e39 ("[SCSI] modify scsi to handle new fail fast flags.")
  31  * seems to suggest that the errors it avoids retrying should usually
  32  * be retried.
  33  */
  34 #define MD_FAILFAST     (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)
  35 /*
  36  * MD's 'extended' device
  37  */
  38 struct md_rdev {
  39         struct list_head same_set;      /* RAID devices within the same set */
  40
  41         sector_t sectors;               /* Device size (in 512bytes sectors) */
  42         struct mddev *mddev;            /* RAID array if running */
  43         int last_events;                /* IO event timestamp */
  44
  45         /*
  46          * If meta_bdev is non-NULL, it means that a separate device is
  47          * being used to store the metadata (superblock/bitmap) which
  48          * would otherwise be contained on the same device as the data (bdev).
  49          */
  50         struct block_device *meta_bdev;
  51         struct block_device *bdev;      /* block device handle */
  52
  53         struct page     *sb_page, *bb_page;
  54         int             sb_loaded;
  55         __u64           sb_events;
  56         sector_t        data_offset;    /* start of data in array */
  57         sector_t        new_data_offset;/* only relevant while reshaping */
  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;  /* bit set of 'enum flag_bits' bits. */
  76         wait_queue_head_t blocked_wait;
  77
  78         int desc_nr;                    /* descriptor index in the superblock */
  79         int raid_disk;                  /* role of device in array */
  80         int new_raid_disk;              /* role that the device will have in
  81                                          * the array after a level-change completes.
  82                                          */
  83         int saved_raid_disk;            /* role that device used to have in the
  84                                          * array and could again if we did a partial
  85                                          * resync from the bitmap
  86                                          */
  87         union {
  88                 sector_t recovery_offset;/* If this device has been partially
  89                                          * recovered, this is where we were
  90                                          * up to.
  91                                          */
  92                 sector_t journal_tail;  /* If this device is a journal device,
  93                                          * this is the journal tail (journal
  94                                          * recovery start point)
  95                                          */
  96         };
  97
  98         atomic_t        nr_pending;     /* number of pending requests.
  99                                          * only maintained for arrays that
 100                                          * support hot removal
 101                                          */
 102         atomic_t        read_errors;    /* number of consecutive read errors that
 103                                          * we have tried to ignore.
 104                                          */
 105         time64_t        last_read_error;        /* monotonic time since our
 106                                                  * last read error
 107                                                  */
 108         atomic_t        corrected_errors; /* number of corrected read errors,
 109                                            * for reporting to userspace and storing
 110                                            * in superblock.
 111                                            */
 112
 113         /*
 114          * The members for check collision of write behind IOs.
 115          */
 116         struct list_head wb_list;
 117         spinlock_t wb_list_lock;
 118         wait_queue_head_t wb_io_wait;
 119
 120         struct work_struct del_work;    /* used for delayed sysfs removal */
 121
 122         struct kernfs_node *sysfs_state; /* handle for 'state'
 123                                            * sysfs entry */
 124
 125         struct badblocks badblocks;
 126
 127         struct {
 128                 short offset;   /* Offset from superblock to start of PPL.
 129                                  * Not used by external metadata. */
 130                 unsigned int size;      /* Size in sectors of the PPL space */
 131                 sector_t sector;        /* First sector of the PPL space */
 132         } ppl;
 133 };
 134 enum flag_bits {
 135         Faulty,                 /* device is known to have a fault */
 136         In_sync,                /* device is in_sync with rest of array */
 137         Bitmap_sync,            /* ..actually, not quite In_sync.  Need a
 138                                  * bitmap-based recovery to get fully in sync.
 139                                  * The bit is only meaningful before device
 140                                  * has been passed to pers->hot_add_disk.
 141                                  */
 142         WriteMostly,            /* Avoid reading if at all possible */
 143         AutoDetected,           /* added by auto-detect */
 144         Blocked,                /* An error occurred but has not yet
 145                                  * been acknowledged by the metadata
 146                                  * handler, so don't allow writes
 147                                  * until it is cleared */
 148         WriteErrorSeen,         /* A write error has been seen on this
 149                                  * device
 150                                  */
 151         FaultRecorded,          /* Intermediate state for clearing
 152                                  * Blocked.  The Fault is/will-be
 153                                  * recorded in the metadata, but that
 154                                  * metadata hasn't been stored safely
 155                                  * on disk yet.
 156                                  */
 157         BlockedBadBlocks,       /* A writer is blocked because they
 158                                  * found an unacknowledged bad-block.
 159                                  * This can safely be cleared at any
 160                                  * time, and the writer will re-check.
 161                                  * It may be set at any time, and at
 162                                  * worst the writer will timeout and
 163                                  * re-check.  So setting it as
 164                                  * accurately as possible is good, but
 165                                  * not absolutely critical.
 166                                  */
 167         WantReplacement,        /* This device is a candidate to be
 168                                  * hot-replaced, either because it has
 169                                  * reported some faults, or because
 170                                  * of explicit request.
 171                                  */
 172         Replacement,            /* This device is a replacement for
 173                                  * a want_replacement device with same
 174                                  * raid_disk number.
 175                                  */
 176         Candidate,              /* For clustered environments only:
 177                                  * This device is seen locally but not
 178                                  * by the whole cluster
 179                                  */
 180         Journal,                /* This device is used as journal for
 181                                  * raid-5/6.
 182                                  * Usually, this device should be faster
 183                                  * than other devices in the array
 184                                  */
 185         ClusterRemove,
 186         RemoveSynchronized,     /* synchronize_rcu() was called after
 187                                  * this device was known to be faulty,
 188                                  * so it is safe to remove without
 189                                  * another synchronize_rcu() call.
 190                                  */
 191         ExternalBbl,            /* External metadata provides bad
 192                                  * block management for a disk
 193                                  */
 194         FailFast,               /* Minimal retries should be attempted on
 195                                  * this device, so use REQ_FAILFAST_DEV.
 196                                  * Also don't try to repair failed reads.
 197                                  * It is expects that no bad block log
 198                                  * is present.
 199                                  */
 200         LastDev,                /* Seems to be the last working dev as
 201                                  * it didn't fail, so don't use FailFast
 202                                  * any more for metadata
 203                                  */
 204         WBCollisionCheck,       /*
 205                                  * multiqueue device should check if there
 206                                  * is collision between write behind bios.
 207                                  */
 208 };
 209
 210 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
 211                               sector_t *first_bad, int *bad_sectors)
 212 {
 213         if (unlikely(rdev->badblocks.count)) {
 214                 int rv = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
 215                                         sectors,
 216                                         first_bad, bad_sectors);
 217                 if (rv)
 218                         *first_bad -= rdev->data_offset;
 219                 return rv;
 220         }
 221         return 0;
 222 }
 223 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 224                               int is_new);
 225 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
 226                                 int is_new);
 227 struct md_cluster_info;
 228
 229 /* change UNSUPPORTED_MDDEV_FLAGS for each array type if new flag is added */
 230 enum mddev_flags {
 231         MD_ARRAY_FIRST_USE,     /* First use of array, needs initialization */
 232         MD_CLOSING,             /* If set, we are closing the array, do not open
 233                                  * it then */
 234         MD_JOURNAL_CLEAN,       /* A raid with journal is already clean */
 235         MD_HAS_JOURNAL,         /* The raid array has journal feature set */
 236         MD_CLUSTER_RESYNC_LOCKED, /* cluster raid only, which means node
 237                                    * already took resync lock, need to
 238                                    * release the lock */
 239         MD_FAILFAST_SUPPORTED,  /* Using MD_FAILFAST on metadata writes is
 240                                  * supported as calls to md_error() will
 241                                  * never cause the array to become failed.
 242                                  */
 243         MD_HAS_PPL,             /* The raid array has PPL feature set */
 244         MD_HAS_MULTIPLE_PPLS,   /* The raid array has multiple PPLs feature set */
 245         MD_ALLOW_SB_UPDATE,     /* md_check_recovery is allowed to update
 246                                  * the metadata without taking reconfig_mutex.
 247                                  */
 248         MD_UPDATING_SB,         /* md_check_recovery is updating the metadata
 249                                  * without explicitly holding reconfig_mutex.
 250                                  */
 251         MD_NOT_READY,           /* do_md_run() is active, so 'array_state'
 252                                  * must not report that array is ready yet
 253                                  */
 254         MD_BROKEN,              /* This is used in RAID-0/LINEAR only, to stop
 255                                  * I/O in case an array member is gone/failed.
 256                                  */
 257 };
 258
 259 enum mddev_sb_flags {
 260         MD_SB_CHANGE_DEVS,              /* Some device status has changed */
 261         MD_SB_CHANGE_CLEAN,     /* transition to or from 'clean' */
 262         MD_SB_CHANGE_PENDING,   /* switch from 'clean' to 'active' in progress */
 263         MD_SB_NEED_REWRITE,     /* metadata write needs to be repeated */
 264 };
 265
 266 #define NR_WB_INFOS     8
 267 /* record current range of write behind IOs */
 268 struct wb_info {
 269         sector_t lo;
 270         sector_t hi;
 271         struct list_head list;
 272 };
 273
 274 struct mddev {
 275         void                            *private;
 276         struct md_personality           *pers;
 277         dev_t                           unit;
 278         int                             md_minor;
 279         struct list_head                disks;
 280         unsigned long                   flags;
 281         unsigned long                   sb_flags;
 282
 283         int                             suspended;
 284         atomic_t                        active_io;
 285         int                             ro;
 286         int                             sysfs_active; /* set when sysfs deletes
 287                                                        * are happening, so run/
 288                                                        * takeover/stop are not safe
 289                                                        */
 290         struct gendisk                  *gendisk;
 291
 292         struct kobject                  kobj;
 293         int                             hold_active;
 294 #define UNTIL_IOCTL     1
 295 #define UNTIL_STOP      2
 296
 297         /* Superblock information */
 298         int                             major_version,
 299                                         minor_version,
 300                                         patch_version;
 301         int                             persistent;
 302         int                             external;       /* metadata is
 303                                                          * managed externally */
 304         char                            metadata_type[17]; /* externally set*/
 305         int                             chunk_sectors;
 306         time64_t                        ctime, utime;
 307         int                             level, layout;
 308         char                            clevel[16];
 309         int                             raid_disks;
 310         int                             max_disks;
 311         sector_t                        dev_sectors;    /* used size of
 312                                                          * component devices */
 313         sector_t                        array_sectors; /* exported array size */
 314         int                             external_size; /* size managed
 315                                                         * externally */
 316         __u64                           events;
 317         /* If the last 'event' was simply a clean->dirty transition, and
 318          * we didn't write it to the spares, then it is safe and simple
 319          * to just decrement the event count on a dirty->clean transition.
 320          * So we record that possibility here.
 321          */
 322         int                             can_decrease_events;
 323
 324         char                            uuid[16];
 325
 326         /* If the array is being reshaped, we need to record the
 327          * new shape and an indication of where we are up to.
 328          * This is written to the superblock.
 329          * If reshape_position is MaxSector, then no reshape is happening (yet).
 330          */
 331         sector_t                        reshape_position;
 332         int                             delta_disks, new_level, new_layout;
 333         int                             new_chunk_sectors;
 334         int                             reshape_backwards;
 335
 336         struct md_thread                *thread;        /* management thread */
 337         struct md_thread                *sync_thread;   /* doing resync or reconstruct */
 338
 339         /* 'last_sync_action' is initialized to "none".  It is set when a
 340          * sync operation (i.e "data-check", "requested-resync", "resync",
 341          * "recovery", or "reshape") is started.  It holds this value even
 342          * when the sync thread is "frozen" (interrupted) or "idle" (stopped
 343          * or finished).  It is overwritten when a new sync operation is begun.
 344          */
 345         char                            *last_sync_action;
 346         sector_t                        curr_resync;    /* last block scheduled */
 347         /* As resync requests can complete out of order, we cannot easily track
 348          * how much resync has been completed.  So we occasionally pause until
 349          * everything completes, then set curr_resync_completed to curr_resync.
 350          * As such it may be well behind the real resync mark, but it is a value
 351          * we are certain of.
 352          */
 353         sector_t                        curr_resync_completed;
 354         unsigned long                   resync_mark;    /* a recent timestamp */
 355         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 356         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 357
 358         sector_t                        resync_max_sectors; /* may be set by personality */
 359
 360         atomic64_t                      resync_mismatches; /* count of sectors where
 361                                                             * parity/replica mismatch found
 362                                                             */
 363
 364         /* allow user-space to request suspension of IO to regions of the array */
 365         sector_t                        suspend_lo;
 366         sector_t                        suspend_hi;
 367         /* if zero, use the system-wide default */
 368         int                             sync_speed_min;
 369         int                             sync_speed_max;
 370
 371         /* resync even though the same disks are shared among md-devices */
 372         int                             parallel_resync;
 373
 374         int                             ok_start_degraded;
 375
 376         unsigned long                   recovery;
 377         /* If a RAID personality determines that recovery (of a particular
 378          * device) will fail due to a read error on the source device, it
 379          * takes a copy of this number and does not attempt recovery again
 380          * until this number changes.
 381          */
 382         int                             recovery_disabled;
 383
 384         int                             in_sync;        /* know to not need resync */
 385         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 386          * that we are never stopping an array while it is open.
 387          * 'reconfig_mutex' protects all other reconfiguration.
 388          * These locks are separate due to conflicting interactions
 389          * with bdev->bd_mutex.
 390          * Lock ordering is:
 391          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 392          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 393          */
 394         struct mutex                    open_mutex;
 395         struct mutex                    reconfig_mutex;
 396         atomic_t                        active;         /* general refcount */
 397         atomic_t                        openers;        /* number of active opens */
 398
 399         int                             changed;        /* True if we might need to
 400                                                          * reread partition info */
 401         int                             degraded;       /* whether md should consider
 402                                                          * adding a spare
 403                                                          */
 404
 405         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 406         wait_queue_head_t               recovery_wait;
 407         sector_t                        recovery_cp;
 408         sector_t                        resync_min;     /* user requested sync
 409                                                          * starts here */
 410         sector_t                        resync_max;     /* resync should pause
 411                                                          * when it gets here */
 412
 413         struct kernfs_node              *sysfs_state;   /* handle for 'array_state'
 414                                                          * file in sysfs.
 415                                                          */
 416         struct kernfs_node              *sysfs_action;  /* handle for 'sync_action' */
 417
 418         struct work_struct del_work;    /* used for delayed sysfs removal */
 419
 420         /* "lock" protects:
 421          *   flush_bio transition from NULL to !NULL
 422          *   rdev superblocks, events
 423          *   clearing MD_CHANGE_*
 424          *   in_sync - and related safemode and MD_CHANGE changes
 425          *   pers (also protected by reconfig_mutex and pending IO).
 426          *   clearing ->bitmap
 427          *   clearing ->bitmap_info.file
 428          *   changing ->resync_{min,max}
 429          *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
 430          */
 431         spinlock_t                      lock;
 432         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 433         atomic_t                        pending_writes; /* number of active superblock writes */
 434
 435         unsigned int                    safemode;       /* if set, update "clean" superblock
 436                                                          * when no writes pending.
 437                                                          */
 438         unsigned int                    safemode_delay;
 439         struct timer_list               safemode_timer;
 440         struct percpu_ref               writes_pending;
 441         int                             sync_checkers;  /* # of threads checking writes_pending */
 442         struct request_queue            *queue; /* for plugging ... */
 443
 444         struct bitmap                   *bitmap; /* the bitmap for the device */
 445         struct {
 446                 struct file             *file; /* the bitmap file */
 447                 loff_t                  offset; /* offset from superblock of
 448                                                  * start of bitmap. May be
 449                                                  * negative, but not '0'
 450                                                  * For external metadata, offset
 451                                                  * from start of device.
 452                                                  */
 453                 unsigned long           space; /* space available at this offset */
 454                 loff_t                  default_offset; /* this is the offset to use when
 455                                                          * hot-adding a bitmap.  It should
 456                                                          * eventually be settable by sysfs.
 457                                                          */
 458                 unsigned long           default_space; /* space available at
 459                                                         * default offset */
 460                 struct mutex            mutex;
 461                 unsigned long           chunksize;
 462                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
 463                 unsigned long           max_write_behind; /* write-behind mode */
 464                 int                     external;
 465                 int                     nodes; /* Maximum number of nodes in the cluster */
 466                 char                    cluster_name[64]; /* Name of the cluster */
 467         } bitmap_info;
 468
 469         atomic_t                        max_corr_read_errors; /* max read retries */
 470         struct list_head                all_mddevs;
 471
 472         struct attribute_group          *to_remove;
 473
 474         struct bio_set                  bio_set;
 475         struct bio_set                  sync_set; /* for sync operations like
 476                                                    * metadata and bitmap writes
 477                                                    */
 478
 479         /* Generic flush handling.
 480          * The last to finish preflush schedules a worker to submit
 481          * the rest of the request (without the REQ_PREFLUSH flag).
 482          */
 483         struct bio *flush_bio;
 484         atomic_t flush_pending;
 485         ktime_t start_flush, last_flush; /* last_flush is when the last completed
 486                                           * flush was started.
 487                                           */
 488         struct work_struct flush_work;
 489         struct work_struct event_work;  /* used by dm to report failure event */
 490         mempool_t *wb_info_pool;
 491         void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 492         struct md_cluster_info          *cluster_info;
 493         unsigned int                    good_device_nr; /* good device num within cluster raid */
 494
 495         bool    has_superblocks:1;
 496         bool    fail_last_dev:1;
 497 };
 498
 499 enum recovery_flags {
 500         /*
 501          * If neither SYNC or RESHAPE are set, then it is a recovery.
 502          */
 503         MD_RECOVERY_RUNNING,    /* a thread is running, or about to be started */
 504         MD_RECOVERY_SYNC,       /* actually doing a resync, not a recovery */
 505         MD_RECOVERY_RECOVER,    /* doing recovery, or need to try it. */
 506         MD_RECOVERY_INTR,       /* resync needs to be aborted for some reason */
 507         MD_RECOVERY_DONE,       /* thread is done and is waiting to be reaped */
 508         MD_RECOVERY_NEEDED,     /* we might need to start a resync/recover */
 509         MD_RECOVERY_REQUESTED,  /* user-space has requested a sync (used with SYNC) */
 510         MD_RECOVERY_CHECK,      /* user-space request for check-only, no repair */
 511         MD_RECOVERY_RESHAPE,    /* A reshape is happening */
 512         MD_RECOVERY_FROZEN,     /* User request to abort, and not restart, any action */
 513         MD_RECOVERY_ERROR,      /* sync-action interrupted because io-error */
 514         MD_RECOVERY_WAIT,       /* waiting for pers->start() to finish */
 515         MD_RESYNCING_REMOTE,    /* remote node is running resync thread */
 516 };
 517
 518 static inline int __must_check mddev_lock(struct mddev *mddev)
 519 {
 520         return mutex_lock_interruptible(&mddev->reconfig_mutex);
 521 }
 522
 523 /* Sometimes we need to take the lock in a situation where
 524  * failure due to interrupts is not acceptable.
 525  */
 526 static inline void mddev_lock_nointr(struct mddev *mddev)
 527 {
 528         mutex_lock(&mddev->reconfig_mutex);
 529 }
 530
 531 static inline int mddev_trylock(struct mddev *mddev)
 532 {
 533         return mutex_trylock(&mddev->reconfig_mutex);
 534 }
 535 extern void mddev_unlock(struct mddev *mddev);
 536
 537 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 538 {
 539         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 540 }
 541
 542 static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
 543 {
 544         atomic_add(nr_sectors, &bio->bi_disk->sync_io);
 545 }
 546
 547 struct md_personality
 548 {
 549         char *name;
 550         int level;
 551         struct list_head list;
 552         struct module *owner;
 553         bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);
 554         /*
 555          * start up works that do NOT require md_thread. tasks that
 556          * requires md_thread should go into start()
 557          */
 558         int (*run)(struct mddev *mddev);
 559         /* start up works that require md threads */
 560         int (*start)(struct mddev *mddev);
 561         void (*free)(struct mddev *mddev, void *priv);
 562         void (*status)(struct seq_file *seq, struct mddev *mddev);
 563         /* error_handler must set ->faulty and clear ->in_sync
 564          * if appropriate, and should abort recovery if needed
 565          */
 566         void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
 567         int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
 568         int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
 569         int (*spare_active) (struct mddev *mddev);
 570         sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
 571         int (*resize) (struct mddev *mddev, sector_t sectors);
 572         sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
 573         int (*check_reshape) (struct mddev *mddev);
 574         int (*start_reshape) (struct mddev *mddev);
 575         void (*finish_reshape) (struct mddev *mddev);
 576         void (*update_reshape_pos) (struct mddev *mddev);
 577         /* quiesce suspends or resumes internal processing.
 578          * 1 - stop new actions and wait for action io to complete
 579          * 0 - return to normal behaviour
 580          */
 581         void (*quiesce) (struct mddev *mddev, int quiesce);
 582         /* takeover is used to transition an array from one
 583          * personality to another.  The new personality must be able
 584          * to handle the data in the current layout.
 585          * e.g. 2drive raid1 -> 2drive raid5
 586          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 587          * If the takeover succeeds, a new 'private' structure is returned.
 588          * This needs to be installed and then ->run used to activate the
 589          * array.
 590          */
 591         void *(*takeover) (struct mddev *mddev);
 592         /* congested implements bdi.congested_fn().
 593          * Will not be called while array is 'suspended' */
 594         int (*congested)(struct mddev *mddev, int bits);
 595         /* Changes the consistency policy of an active array. */
 596         int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
 597 };
 598
 599 struct md_sysfs_entry {
 600         struct attribute attr;
 601         ssize_t (*show)(struct mddev *, char *);
 602         ssize_t (*store)(struct mddev *, const char *, size_t);
 603 };
 604 extern struct attribute_group md_bitmap_group;
 605
 606 static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
 607 {
 608         if (sd)
 609                 return sysfs_get_dirent(sd, name);
 610         return sd;
 611 }
 612 static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
 613 {
 614         if (sd)
 615                 sysfs_notify_dirent(sd);
 616 }
 617
 618 static inline char * mdname (struct mddev * mddev)
 619 {
 620         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 621 }
 622
 623 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 624 {
 625         char nm[20];
 626         if (!test_bit(Replacement, &rdev->flags) &&
 627             !test_bit(Journal, &rdev->flags) &&
 628             mddev->kobj.sd) {
 629                 sprintf(nm, "rd%d", rdev->raid_disk);
 630                 return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 631         } else
 632                 return 0;
 633 }
 634
 635 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 636 {
 637         char nm[20];
 638         if (!test_bit(Replacement, &rdev->flags) &&
 639             !test_bit(Journal, &rdev->flags) &&
 640             mddev->kobj.sd) {
 641                 sprintf(nm, "rd%d", rdev->raid_disk);
 642                 sysfs_remove_link(&mddev->kobj, nm);
 643         }
 644 }
 645
 646 /*
 647  * iterates through some rdev ringlist. It's safe to remove the
 648  * current 'rdev'. Dont touch 'tmp' though.
 649  */
 650 #define rdev_for_each_list(rdev, tmp, head)                             \
 651         list_for_each_entry_safe(rdev, tmp, head, same_set)
 652
 653 /*
 654  * iterates through the 'same array disks' ringlist
 655  */
 656 #define rdev_for_each(rdev, mddev)                              \
 657         list_for_each_entry(rdev, &((mddev)->disks), same_set)
 658
 659 #define rdev_for_each_safe(rdev, tmp, mddev)                            \
 660         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 661
 662 #define rdev_for_each_rcu(rdev, mddev)                          \
 663         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 664
 665 struct md_thread {
 666         void                    (*run) (struct md_thread *thread);
 667         struct mddev            *mddev;
 668         wait_queue_head_t       wqueue;
 669         unsigned long           flags;
 670         struct task_struct      *tsk;
 671         unsigned long           timeout;
 672         void                    *private;
 673 };
 674
 675 #define THREAD_WAKEUP  0
 676
 677 static inline void safe_put_page(struct page *p)
 678 {
 679         if (p) put_page(p);
 680 }
 681
 682 extern int register_md_personality(struct md_personality *p);
 683 extern int unregister_md_personality(struct md_personality *p);
 684 extern int register_md_cluster_operations(struct md_cluster_operations *ops,
 685                 struct module *module);
 686 extern int unregister_md_cluster_operations(void);
 687 extern int md_setup_cluster(struct mddev *mddev, int nodes);
 688 extern void md_cluster_stop(struct mddev *mddev);
 689 extern struct md_thread *md_register_thread(
 690         void (*run)(struct md_thread *thread),
 691         struct mddev *mddev,
 692         const char *name);
 693 extern void md_unregister_thread(struct md_thread **threadp);
 694 extern void md_wakeup_thread(struct md_thread *thread);
 695 extern void md_check_recovery(struct mddev *mddev);
 696 extern void md_reap_sync_thread(struct mddev *mddev);
 697 extern int mddev_init_writes_pending(struct mddev *mddev);
 698 extern bool md_write_start(struct mddev *mddev, struct bio *bi);
 699 extern void md_write_inc(struct mddev *mddev, struct bio *bi);
 700 extern void md_write_end(struct mddev *mddev);
 701 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 702 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 703 extern void md_finish_reshape(struct mddev *mddev);
 704
 705 extern int mddev_congested(struct mddev *mddev, int bits);
 706 extern bool __must_check md_flush_request(struct mddev *mddev, struct bio *bio);
 707 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 708                            sector_t sector, int size, struct page *page);
 709 extern int md_super_wait(struct mddev *mddev);
 710 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
 711                         struct page *page, int op, int op_flags,
 712                         bool metadata_op);
 713 extern void md_do_sync(struct md_thread *thread);
 714 extern void md_new_event(struct mddev *mddev);
 715 extern void md_allow_write(struct mddev *mddev);
 716 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
 717 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
 718 extern int md_check_no_bitmap(struct mddev *mddev);
 719 extern int md_integrity_register(struct mddev *mddev);
 720 extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
 721 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 722
 723 extern void mddev_init(struct mddev *mddev);
 724 extern int md_run(struct mddev *mddev);
 725 extern int md_start(struct mddev *mddev);
 726 extern void md_stop(struct mddev *mddev);
 727 extern void md_stop_writes(struct mddev *mddev);
 728 extern int md_rdev_init(struct md_rdev *rdev);
 729 extern void md_rdev_clear(struct md_rdev *rdev);
 730
 731 extern void md_handle_request(struct mddev *mddev, struct bio *bio);
 732 extern void mddev_suspend(struct mddev *mddev);
 733 extern void mddev_resume(struct mddev *mddev);
 734 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 735                                    struct mddev *mddev);
 736
 737 extern void md_reload_sb(struct mddev *mddev, int raid_disk);
 738 extern void md_update_sb(struct mddev *mddev, int force);
 739 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
 740 extern void mddev_create_wb_pool(struct mddev *mddev, struct md_rdev *rdev,
 741                                  bool is_suspend);
 742 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
 743 struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev);
 744
 745 static inline bool is_mddev_broken(struct md_rdev *rdev, const char *md_type)
 746 {
 747         int flags = rdev->bdev->bd_disk->flags;
 748
 749         if (!(flags & GENHD_FL_UP)) {
 750                 if (!test_and_set_bit(MD_BROKEN, &rdev->mddev->flags))
 751                         pr_warn("md: %s: %s array has a missing/failed member\n",
 752                                 mdname(rdev->mddev), md_type);
 753                 return true;
 754         }
 755         return false;
 756 }
 757
 758 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 759 {
 760         int faulty = test_bit(Faulty, &rdev->flags);
 761         if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
 762                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 763                 md_wakeup_thread(mddev->thread);
 764         }
 765 }
 766
 767 extern struct md_cluster_operations *md_cluster_ops;
 768 static inline int mddev_is_clustered(struct mddev *mddev)
 769 {
 770         return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
 771 }
 772
 773 /* clear unsupported mddev_flags */
 774 static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
 775         unsigned long unsupported_flags)
 776 {
 777         mddev->flags &= ~unsupported_flags;
 778 }
 779
 780 static inline void mddev_check_writesame(struct mddev *mddev, struct bio *bio)
 781 {
 782         if (bio_op(bio) == REQ_OP_WRITE_SAME &&
 783             !bio->bi_disk->queue->limits.max_write_same_sectors)
 784                 mddev->queue->limits.max_write_same_sectors = 0;
 785 }
 786
 787 static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
 788 {
 789         if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
 790             !bio->bi_disk->queue->limits.max_write_zeroes_sectors)
 791                 mddev->queue->limits.max_write_zeroes_sectors = 0;
 792 }
 793 #endif /* _MD_MD_H */