drivers/md/md.h

   1 /*
   2    md_k.h : kernel internal structure of the Linux MD driver
   3           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    You should have received a copy of the GNU General Public License
  11    (for example /usr/src/linux/COPYING); if not, write to the Free
  12    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  13 */
  14
  15 #ifndef _MD_MD_H
  16 #define _MD_MD_H
  17
  18 #include <linux/blkdev.h>
  19 #include <linux/kobject.h>
  20 #include <linux/list.h>
  21 #include <linux/mm.h>
  22 #include <linux/mutex.h>
  23 #include <linux/timer.h>
  24 #include <linux/wait.h>
  25 #include <linux/workqueue.h>
  26
  27 #define MaxSector (~(sector_t)0)
  28
  29 typedef struct mddev_s mddev_t;
  30 typedef struct mdk_rdev_s mdk_rdev_t;
  31
  32 /*
  33  * MD's 'extended' device
  34  */
  35 struct mdk_rdev_s
  36 {
  37         struct list_head same_set;      /* RAID devices within the same set */
  38
  39         sector_t sectors;               /* Device size (in 512bytes sectors) */
  40         mddev_t *mddev;                 /* RAID array if running */
  41         int last_events;                /* IO event timestamp */
  42
  43         struct block_device *bdev;      /* block device handle */
  44
  45         struct page     *sb_page;
  46         int             sb_loaded;
  47         __u64           sb_events;
  48         sector_t        data_offset;    /* start of data in array */
  49         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  50         int             sb_size;        /* bytes in the superblock */
  51         int             preferred_minor;        /* autorun support */
  52
  53         struct kobject  kobj;
  54
  55         /* A device can be in one of three states based on two flags:
  56          * Not working:   faulty==1 in_sync==0
  57          * Fully working: faulty==0 in_sync==1
  58          * Working, but not
  59          * in sync with array
  60          *                faulty==0 in_sync==0
  61          *
  62          * It can never have faulty==1, in_sync==1
  63          * This reduces the burden of testing multiple flags in many cases
  64          */
  65
  66         unsigned long   flags;
  67 #define Faulty          1               /* device is known to have a fault */
  68 #define In_sync         2               /* device is in_sync with rest of array */
  69 #define WriteMostly     4               /* Avoid reading if at all possible */
  70 #define BarriersNotsupp 5               /* BIO_RW_BARRIER is not supported */
  71 #define AllReserved     6               /* If whole device is reserved for
  72                                          * one array */
  73 #define AutoDetected    7               /* added by auto-detect */
  74 #define Blocked         8               /* An error occured on an externally
  75                                          * managed array, don't allow writes
  76                                          * until it is cleared */
  77         wait_queue_head_t blocked_wait;
  78
  79         int desc_nr;                    /* descriptor index in the superblock */
  80         int raid_disk;                  /* role of device in array */
  81         int new_raid_disk;              /* role that the device will have in
  82                                          * the array after a level-change completes.
  83                                          */
  84         int saved_raid_disk;            /* role that device used to have in the
  85                                          * array and could again if we did a partial
  86                                          * resync from the bitmap
  87                                          */
  88         sector_t        recovery_offset;/* If this device has been partially
  89                                          * recovered, this is where we were
  90                                          * up to.
  91                                          */
  92
  93         atomic_t        nr_pending;     /* number of pending requests.
  94                                          * only maintained for arrays that
  95                                          * support hot removal
  96                                          */
  97         atomic_t        read_errors;    /* number of consecutive read errors that
  98                                          * we have tried to ignore.
  99                                          */
 100         struct timespec last_read_error;        /* monotonic time since our
 101                                                  * last read error
 102                                                  */
 103         atomic_t        corrected_errors; /* number of corrected read errors,
 104                                            * for reporting to userspace and storing
 105                                            * in superblock.
 106                                            */
 107         struct work_struct del_work;    /* used for delayed sysfs removal */
 108
 109         struct sysfs_dirent *sysfs_state; /* handle for 'state'
 110                                            * sysfs entry */
 111 };
 112
 113 struct mddev_s
 114 {
 115         void                            *private;
 116         struct mdk_personality          *pers;
 117         dev_t                           unit;
 118         int                             md_minor;
 119         struct list_head                disks;
 120         unsigned long                   flags;
 121 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
 122 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 123 #define MD_CHANGE_PENDING 2     /* superblock update in progress */
 124
 125         int                             suspended;
 126         atomic_t                        active_io;
 127         int                             ro;
 128
 129         struct gendisk                  *gendisk;
 130
 131         struct kobject                  kobj;
 132         int                             hold_active;
 133 #define UNTIL_IOCTL     1
 134 #define UNTIL_STOP      2
 135
 136         /* Superblock information */
 137         int                             major_version,
 138                                         minor_version,
 139                                         patch_version;
 140         int                             persistent;
 141         int                             external;       /* metadata is
 142                                                          * managed externally */
 143         char                            metadata_type[17]; /* externally set*/
 144         int                             chunk_sectors;
 145         time_t                          ctime, utime;
 146         int                             level, layout;
 147         char                            clevel[16];
 148         int                             raid_disks;
 149         int                             max_disks;
 150         sector_t                        dev_sectors;    /* used size of
 151                                                          * component devices */
 152         sector_t                        array_sectors; /* exported array size */
 153         int                             external_size; /* size managed
 154                                                         * externally */
 155         __u64                           events;
 156         /* If the last 'event' was simply a clean->dirty transition, and
 157          * we didn't write it to the spares, then it is safe and simple
 158          * to just decrement the event count on a dirty->clean transition.
 159          * So we record that possibility here.
 160          */
 161         int                             can_decrease_events;
 162
 163         char                            uuid[16];
 164
 165         /* If the array is being reshaped, we need to record the
 166          * new shape and an indication of where we are up to.
 167          * This is written to the superblock.
 168          * If reshape_position is MaxSector, then no reshape is happening (yet).
 169          */
 170         sector_t                        reshape_position;
 171         int                             delta_disks, new_level, new_layout;
 172         int                             new_chunk_sectors;
 173
 174         struct mdk_thread_s             *thread;        /* management thread */
 175         struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
 176         sector_t                        curr_resync;    /* last block scheduled */
 177         /* As resync requests can complete out of order, we cannot easily track
 178          * how much resync has been completed.  So we occasionally pause until
 179          * everything completes, then set curr_resync_completed to curr_resync.
 180          * As such it may be well behind the real resync mark, but it is a value
 181          * we are certain of.
 182          */
 183         sector_t                        curr_resync_completed;
 184         unsigned long                   resync_mark;    /* a recent timestamp */
 185         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 186         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 187
 188         sector_t                        resync_max_sectors; /* may be set by personality */
 189
 190         sector_t                        resync_mismatches; /* count of sectors where
 191                                                             * parity/replica mismatch found
 192                                                             */
 193
 194         /* allow user-space to request suspension of IO to regions of the array */
 195         sector_t                        suspend_lo;
 196         sector_t                        suspend_hi;
 197         /* if zero, use the system-wide default */
 198         int                             sync_speed_min;
 199         int                             sync_speed_max;
 200
 201         /* resync even though the same disks are shared among md-devices */
 202         int                             parallel_resync;
 203
 204         int                             ok_start_degraded;
 205         /* recovery/resync flags
 206          * NEEDED:   we might need to start a resync/recover
 207          * RUNNING:  a thread is running, or about to be started
 208          * SYNC:     actually doing a resync, not a recovery
 209          * RECOVER:  doing recovery, or need to try it.
 210          * INTR:     resync needs to be aborted for some reason
 211          * DONE:     thread is done and is waiting to be reaped
 212          * REQUEST:  user-space has requested a sync (used with SYNC)
 213          * CHECK:    user-space request for check-only, no repair
 214          * RESHAPE:  A reshape is happening
 215          *
 216          * If neither SYNC or RESHAPE are set, then it is a recovery.
 217          */
 218 #define MD_RECOVERY_RUNNING     0
 219 #define MD_RECOVERY_SYNC        1
 220 #define MD_RECOVERY_RECOVER     2
 221 #define MD_RECOVERY_INTR        3
 222 #define MD_RECOVERY_DONE        4
 223 #define MD_RECOVERY_NEEDED      5
 224 #define MD_RECOVERY_REQUESTED   6
 225 #define MD_RECOVERY_CHECK       7
 226 #define MD_RECOVERY_RESHAPE     8
 227 #define MD_RECOVERY_FROZEN      9
 228
 229         unsigned long                   recovery;
 230         int                             recovery_disabled; /* if we detect that recovery
 231                                                             * will always fail, set this
 232                                                             * so we don't loop trying */
 233
 234         int                             in_sync;        /* know to not need resync */
 235         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 236          * that we are never stopping an array while it is open.
 237          * 'reconfig_mutex' protects all other reconfiguration.
 238          * These locks are separate due to conflicting interactions
 239          * with bdev->bd_mutex.
 240          * Lock ordering is:
 241          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 242          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 243          */
 244         struct mutex                    open_mutex;
 245         struct mutex                    reconfig_mutex;
 246         atomic_t                        active;         /* general refcount */
 247         atomic_t                        openers;        /* number of active opens */
 248
 249         int                             degraded;       /* whether md should consider
 250                                                          * adding a spare
 251                                                          */
 252         int                             barriers_work;  /* initialised to true, cleared as soon
 253                                                          * as a barrier request to slave
 254                                                          * fails.  Only supported
 255                                                          */
 256         struct bio                      *biolist;       /* bios that need to be retried
 257                                                          * because BIO_RW_BARRIER is not supported
 258                                                          */
 259
 260         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 261         wait_queue_head_t               recovery_wait;
 262         sector_t                        recovery_cp;
 263         sector_t                        resync_min;     /* user requested sync
 264                                                          * starts here */
 265         sector_t                        resync_max;     /* resync should pause
 266                                                          * when it gets here */
 267
 268         struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
 269                                                          * file in sysfs.
 270                                                          */
 271         struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
 272
 273         struct work_struct del_work;    /* used for delayed sysfs removal */
 274
 275         spinlock_t                      write_lock;
 276         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 277         atomic_t                        pending_writes; /* number of active superblock writes */
 278
 279         unsigned int                    safemode;       /* if set, update "clean" superblock
 280                                                          * when no writes pending.
 281                                                          */
 282         unsigned int                    safemode_delay;
 283         struct timer_list               safemode_timer;
 284         atomic_t                        writes_pending;
 285         struct request_queue            *queue; /* for plugging ... */
 286
 287         struct bitmap                   *bitmap; /* the bitmap for the device */
 288         struct {
 289                 struct file             *file; /* the bitmap file */
 290                 loff_t                  offset; /* offset from superblock of
 291                                                  * start of bitmap. May be
 292                                                  * negative, but not '0'
 293                                                  * For external metadata, offset
 294                                                  * from start of device.
 295                                                  */
 296                 loff_t                  default_offset; /* this is the offset to use when
 297                                                          * hot-adding a bitmap.  It should
 298                                                          * eventually be settable by sysfs.
 299                                                          */
 300                 struct mutex            mutex;
 301                 unsigned long           chunksize;
 302                 unsigned long           daemon_sleep; /* how many seconds between updates? */
 303                 unsigned long           max_write_behind; /* write-behind mode */
 304                 int                     external;
 305         } bitmap_info;
 306
 307         atomic_t                        max_corr_read_errors; /* max read retries */
 308         struct list_head                all_mddevs;
 309
 310         struct attribute_group          *to_remove;
 311         /* Generic barrier handling.
 312          * If there is a pending barrier request, all other
 313          * writes are blocked while the devices are flushed.
 314          * The last to finish a flush schedules a worker to
 315          * submit the barrier request (without the barrier flag),
 316          * then submit more flush requests.
 317          */
 318         struct bio *barrier;
 319         atomic_t flush_pending;
 320         struct work_struct barrier_work;
 321         struct work_struct event_work;  /* used by dm to report failure event */
 322 };
 323
 324
 325 static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
 326 {
 327         int faulty = test_bit(Faulty, &rdev->flags);
 328         if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
 329                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 330 }
 331
 332 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 333 {
 334         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 335 }
 336
 337 struct mdk_personality
 338 {
 339         char *name;
 340         int level;
 341         struct list_head list;
 342         struct module *owner;
 343         int (*make_request)(mddev_t *mddev, struct bio *bio);
 344         int (*run)(mddev_t *mddev);
 345         int (*stop)(mddev_t *mddev);
 346         void (*status)(struct seq_file *seq, mddev_t *mddev);
 347         /* error_handler must set ->faulty and clear ->in_sync
 348          * if appropriate, and should abort recovery if needed
 349          */
 350         void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
 351         int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
 352         int (*hot_remove_disk) (mddev_t *mddev, int number);
 353         int (*spare_active) (mddev_t *mddev);
 354         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
 355         int (*resize) (mddev_t *mddev, sector_t sectors);
 356         sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
 357         int (*check_reshape) (mddev_t *mddev);
 358         int (*start_reshape) (mddev_t *mddev);
 359         void (*finish_reshape) (mddev_t *mddev);
 360         /* quiesce moves between quiescence states
 361          * 0 - fully active
 362          * 1 - no new requests allowed
 363          * others - reserved
 364          */
 365         void (*quiesce) (mddev_t *mddev, int state);
 366         /* takeover is used to transition an array from one
 367          * personality to another.  The new personality must be able
 368          * to handle the data in the current layout.
 369          * e.g. 2drive raid1 -> 2drive raid5
 370          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 371          * If the takeover succeeds, a new 'private' structure is returned.
 372          * This needs to be installed and then ->run used to activate the
 373          * array.
 374          */
 375         void *(*takeover) (mddev_t *mddev);
 376 };
 377
 378
 379 struct md_sysfs_entry {
 380         struct attribute attr;
 381         ssize_t (*show)(mddev_t *, char *);
 382         ssize_t (*store)(mddev_t *, const char *, size_t);
 383 };
 384 extern struct attribute_group md_bitmap_group;
 385
 386 static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
 387 {
 388         if (sd)
 389                 return sysfs_get_dirent(sd, NULL, name);
 390         return sd;
 391 }
 392 static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
 393 {
 394         if (sd)
 395                 sysfs_notify_dirent(sd);
 396 }
 397
 398 static inline char * mdname (mddev_t * mddev)
 399 {
 400         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 401 }
 402
 403 /*
 404  * iterates through some rdev ringlist. It's safe to remove the
 405  * current 'rdev'. Dont touch 'tmp' though.
 406  */
 407 #define rdev_for_each_list(rdev, tmp, head)                             \
 408         list_for_each_entry_safe(rdev, tmp, head, same_set)
 409
 410 /*
 411  * iterates through the 'same array disks' ringlist
 412  */
 413 #define rdev_for_each(rdev, tmp, mddev)                         \
 414         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 415
 416 #define rdev_for_each_rcu(rdev, mddev)                          \
 417         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 418
 419 typedef struct mdk_thread_s {
 420         void                    (*run) (mddev_t *mddev);
 421         mddev_t                 *mddev;
 422         wait_queue_head_t       wqueue;
 423         unsigned long           flags;
 424         struct task_struct      *tsk;
 425         unsigned long           timeout;
 426 } mdk_thread_t;
 427
 428 #define THREAD_WAKEUP  0
 429
 430 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 431 do {                                                                    \
 432         wait_queue_t __wait;                                            \
 433         init_waitqueue_entry(&__wait, current);                         \
 434                                                                         \
 435         add_wait_queue(&wq, &__wait);                                   \
 436         for (;;) {                                                      \
 437                 set_current_state(TASK_UNINTERRUPTIBLE);                \
 438                 if (condition)                                          \
 439                         break;                                          \
 440                 spin_unlock_irq(&lock);                                 \
 441                 cmd;                                                    \
 442                 schedule();                                             \
 443                 spin_lock_irq(&lock);                                   \
 444         }                                                               \
 445         current->state = TASK_RUNNING;                                  \
 446         remove_wait_queue(&wq, &__wait);                                \
 447 } while (0)
 448
 449 #define wait_event_lock_irq(wq, condition, lock, cmd)                   \
 450 do {                                                                    \
 451         if (condition)                                                  \
 452                 break;                                                  \
 453         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 454 } while (0)
 455
 456 static inline void safe_put_page(struct page *p)
 457 {
 458         if (p) put_page(p);
 459 }
 460
 461 extern int register_md_personality(struct mdk_personality *p);
 462 extern int unregister_md_personality(struct mdk_personality *p);
 463 extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
 464                                 mddev_t *mddev, const char *name);
 465 extern void md_unregister_thread(mdk_thread_t *thread);
 466 extern void md_wakeup_thread(mdk_thread_t *thread);
 467 extern void md_check_recovery(mddev_t *mddev);
 468 extern void md_write_start(mddev_t *mddev, struct bio *bi);
 469 extern void md_write_end(mddev_t *mddev);
 470 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 471 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 472
 473 extern int mddev_congested(mddev_t *mddev, int bits);
 474 extern void md_barrier_request(mddev_t *mddev, struct bio *bio);
 475 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 476                            sector_t sector, int size, struct page *page);
 477 extern void md_super_wait(mddev_t *mddev);
 478 extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
 479                         struct page *page, int rw);
 480 extern void md_do_sync(mddev_t *mddev);
 481 extern void md_new_event(mddev_t *mddev);
 482 extern int md_allow_write(mddev_t *mddev);
 483 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 484 extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
 485 extern int md_check_no_bitmap(mddev_t *mddev);
 486 extern int md_integrity_register(mddev_t *mddev);
 487 extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 488 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 489 extern void restore_bitmap_write_access(struct file *file);
 490
 491 extern void mddev_init(mddev_t *mddev);
 492 extern int md_run(mddev_t *mddev);
 493 extern void md_stop(mddev_t *mddev);
 494 extern void md_stop_writes(mddev_t *mddev);
 495 extern void md_rdev_init(mdk_rdev_t *rdev);
 496
 497 extern void mddev_suspend(mddev_t *mddev);
 498 extern void mddev_resume(mddev_t *mddev);
 499 #endif /* _MD_MD_H */