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  * options passed in raidrun:
  34  */
  35
  36 /* Currently this must fit in an 'int' */
  37 #define MAX_CHUNK_SIZE (1<<30)
  38
  39 /*
  40  * MD's 'extended' device
  41  */
  42 struct mdk_rdev_s
  43 {
  44         struct list_head same_set;      /* RAID devices within the same set */
  45
  46         sector_t sectors;               /* Device size (in 512bytes sectors) */
  47         mddev_t *mddev;                 /* RAID array if running */
  48         int last_events;                /* IO event timestamp */
  49
  50         struct block_device *bdev;      /* block device handle */
  51
  52         struct page     *sb_page;
  53         int             sb_loaded;
  54         __u64           sb_events;
  55         sector_t        data_offset;    /* start of data in array */
  56         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  57         int             sb_size;        /* bytes in the superblock */
  58         int             preferred_minor;        /* autorun support */
  59
  60         struct kobject  kobj;
  61
  62         /* A device can be in one of three states based on two flags:
  63          * Not working:   faulty==1 in_sync==0
  64          * Fully working: faulty==0 in_sync==1
  65          * Working, but not
  66          * in sync with array
  67          *                faulty==0 in_sync==0
  68          *
  69          * It can never have faulty==1, in_sync==1
  70          * This reduces the burden of testing multiple flags in many cases
  71          */
  72
  73         unsigned long   flags;
  74 #define Faulty          1               /* device is known to have a fault */
  75 #define In_sync         2               /* device is in_sync with rest of array */
  76 #define WriteMostly     4               /* Avoid reading if at all possible */
  77 #define BarriersNotsupp 5               /* BIO_RW_BARRIER is not supported */
  78 #define AllReserved     6               /* If whole device is reserved for
  79                                          * one array */
  80 #define AutoDetected    7               /* added by auto-detect */
  81 #define Blocked         8               /* An error occured on an externally
  82                                          * managed array, don't allow writes
  83                                          * until it is cleared */
  84 #define StateChanged    9               /* Faulty or Blocked has changed during
  85                                          * interrupt, so it needs to be
  86                                          * notified by the thread */
  87         wait_queue_head_t blocked_wait;
  88
  89         int desc_nr;                    /* descriptor index in the superblock */
  90         int raid_disk;                  /* role of device in array */
  91         int saved_raid_disk;            /* role that device used to have in the
  92                                          * array and could again if we did a partial
  93                                          * resync from the bitmap
  94                                          */
  95         sector_t        recovery_offset;/* If this device has been partially
  96                                          * recovered, this is where we were
  97                                          * up to.
  98                                          */
  99
 100         atomic_t        nr_pending;     /* number of pending requests.
 101                                          * only maintained for arrays that
 102                                          * support hot removal
 103                                          */
 104         atomic_t        read_errors;    /* number of consecutive read errors that
 105                                          * we have tried to ignore.
 106                                          */
 107         atomic_t        corrected_errors; /* number of corrected read errors,
 108                                            * for reporting to userspace and storing
 109                                            * in superblock.
 110                                            */
 111         struct work_struct del_work;    /* used for delayed sysfs removal */
 112
 113         struct sysfs_dirent *sysfs_state; /* handle for 'state'
 114                                            * sysfs entry */
 115 };
 116
 117 struct mddev_s
 118 {
 119         void                            *private;
 120         struct mdk_personality          *pers;
 121         dev_t                           unit;
 122         int                             md_minor;
 123         struct list_head                disks;
 124         unsigned long                   flags;
 125 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
 126 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 127 #define MD_CHANGE_PENDING 2     /* superblock update in progress */
 128
 129         int                             suspended;
 130         atomic_t                        active_io;
 131         int                             ro;
 132
 133         struct gendisk                  *gendisk;
 134
 135         struct kobject                  kobj;
 136         int                             hold_active;
 137 #define UNTIL_IOCTL     1
 138 #define UNTIL_STOP      2
 139
 140         /* Superblock information */
 141         int                             major_version,
 142                                         minor_version,
 143                                         patch_version;
 144         int                             persistent;
 145         int                             external;       /* metadata is
 146                                                          * managed externally */
 147         char                            metadata_type[17]; /* externally set*/
 148         int                             chunk_size;
 149         time_t                          ctime, utime;
 150         int                             level, layout;
 151         char                            clevel[16];
 152         int                             raid_disks;
 153         int                             max_disks;
 154         sector_t                        dev_sectors;    /* used size of
 155                                                          * component devices */
 156         sector_t                        array_sectors; /* exported array size */
 157         int                             external_size; /* size managed
 158                                                         * externally */
 159         __u64                           events;
 160
 161         char                            uuid[16];
 162
 163         /* If the array is being reshaped, we need to record the
 164          * new shape and an indication of where we are up to.
 165          * This is written to the superblock.
 166          * If reshape_position is MaxSector, then no reshape is happening (yet).
 167          */
 168         sector_t                        reshape_position;
 169         int                             delta_disks, new_level, new_layout, new_chunk;
 170
 171         struct mdk_thread_s             *thread;        /* management thread */
 172         struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
 173         sector_t                        curr_resync;    /* last block scheduled */
 174         /* As resync requests can complete out of order, we cannot easily track
 175          * how much resync has been completed.  So we occasionally pause until
 176          * everything completes, then set curr_resync_completed to curr_resync.
 177          * As such it may be well behind the real resync mark, but it is a value
 178          * we are certain of.
 179          */
 180         sector_t                        curr_resync_completed;
 181         unsigned long                   resync_mark;    /* a recent timestamp */
 182         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 183         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 184
 185         sector_t                        resync_max_sectors; /* may be set by personality */
 186
 187         sector_t                        resync_mismatches; /* count of sectors where
 188                                                             * parity/replica mismatch found
 189                                                             */
 190
 191         /* allow user-space to request suspension of IO to regions of the array */
 192         sector_t                        suspend_lo;
 193         sector_t                        suspend_hi;
 194         /* if zero, use the system-wide default */
 195         int                             sync_speed_min;
 196         int                             sync_speed_max;
 197
 198         /* resync even though the same disks are shared among md-devices */
 199         int                             parallel_resync;
 200
 201         int                             ok_start_degraded;
 202         /* recovery/resync flags
 203          * NEEDED:   we might need to start a resync/recover
 204          * RUNNING:  a thread is running, or about to be started
 205          * SYNC:     actually doing a resync, not a recovery
 206          * RECOVER:  doing recovery, or need to try it.
 207          * INTR:     resync needs to be aborted for some reason
 208          * DONE:     thread is done and is waiting to be reaped
 209          * REQUEST:  user-space has requested a sync (used with SYNC)
 210          * CHECK:    user-space request for for check-only, no repair
 211          * RESHAPE:  A reshape is happening
 212          *
 213          * If neither SYNC or RESHAPE are set, then it is a recovery.
 214          */
 215 #define MD_RECOVERY_RUNNING     0
 216 #define MD_RECOVERY_SYNC        1
 217 #define MD_RECOVERY_RECOVER     2
 218 #define MD_RECOVERY_INTR        3
 219 #define MD_RECOVERY_DONE        4
 220 #define MD_RECOVERY_NEEDED      5
 221 #define MD_RECOVERY_REQUESTED   6
 222 #define MD_RECOVERY_CHECK       7
 223 #define MD_RECOVERY_RESHAPE     8
 224 #define MD_RECOVERY_FROZEN      9
 225
 226         unsigned long                   recovery;
 227         int                             recovery_disabled; /* if we detect that recovery
 228                                                             * will always fail, set this
 229                                                             * so we don't loop trying */
 230
 231         int                             in_sync;        /* know to not need resync */
 232         struct mutex                    reconfig_mutex;
 233         atomic_t                        active;         /* general refcount */
 234         atomic_t                        openers;        /* number of active opens */
 235
 236         int                             changed;        /* true if we might need to reread partition info */
 237         int                             degraded;       /* whether md should consider
 238                                                          * adding a spare
 239                                                          */
 240         int                             barriers_work;  /* initialised to true, cleared as soon
 241                                                          * as a barrier request to slave
 242                                                          * fails.  Only supported
 243                                                          */
 244         struct bio                      *biolist;       /* bios that need to be retried
 245                                                          * because BIO_RW_BARRIER is not supported
 246                                                          */
 247
 248         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 249         wait_queue_head_t               recovery_wait;
 250         sector_t                        recovery_cp;
 251         sector_t                        resync_min;     /* user requested sync
 252                                                          * starts here */
 253         sector_t                        resync_max;     /* resync should pause
 254                                                          * when it gets here */
 255
 256         struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
 257                                                          * file in sysfs.
 258                                                          */
 259         struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
 260
 261         struct work_struct del_work;    /* used for delayed sysfs removal */
 262
 263         spinlock_t                      write_lock;
 264         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 265         atomic_t                        pending_writes; /* number of active superblock writes */
 266
 267         unsigned int                    safemode;       /* if set, update "clean" superblock
 268                                                          * when no writes pending.
 269                                                          */
 270         unsigned int                    safemode_delay;
 271         struct timer_list               safemode_timer;
 272         atomic_t                        writes_pending;
 273         struct request_queue            *queue; /* for plugging ... */
 274
 275         atomic_t                        write_behind; /* outstanding async IO */
 276         unsigned int                    max_write_behind; /* 0 = sync */
 277
 278         struct bitmap                   *bitmap; /* the bitmap for the device */
 279         struct file                     *bitmap_file; /* the bitmap file */
 280         long                            bitmap_offset; /* offset from superblock of
 281                                                         * start of bitmap. May be
 282                                                         * negative, but not '0'
 283                                                         */
 284         long                            default_bitmap_offset; /* this is the offset to use when
 285                                                                 * hot-adding a bitmap.  It should
 286                                                                 * eventually be settable by sysfs.
 287                                                                 */
 288
 289         struct list_head                all_mddevs;
 290 };
 291
 292
 293 static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
 294 {
 295         int faulty = test_bit(Faulty, &rdev->flags);
 296         if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
 297                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 298 }
 299
 300 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 301 {
 302         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 303 }
 304
 305 struct mdk_personality
 306 {
 307         char *name;
 308         int level;
 309         struct list_head list;
 310         struct module *owner;
 311         int (*make_request)(struct request_queue *q, struct bio *bio);
 312         int (*run)(mddev_t *mddev);
 313         int (*stop)(mddev_t *mddev);
 314         void (*status)(struct seq_file *seq, mddev_t *mddev);
 315         /* error_handler must set ->faulty and clear ->in_sync
 316          * if appropriate, and should abort recovery if needed
 317          */
 318         void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
 319         int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
 320         int (*hot_remove_disk) (mddev_t *mddev, int number);
 321         int (*spare_active) (mddev_t *mddev);
 322         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
 323         int (*resize) (mddev_t *mddev, sector_t sectors);
 324         sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
 325         int (*check_reshape) (mddev_t *mddev);
 326         int (*start_reshape) (mddev_t *mddev);
 327         void (*finish_reshape) (mddev_t *mddev);
 328         int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);
 329         /* quiesce moves between quiescence states
 330          * 0 - fully active
 331          * 1 - no new requests allowed
 332          * others - reserved
 333          */
 334         void (*quiesce) (mddev_t *mddev, int state);
 335         /* takeover is used to transition an array from one
 336          * personality to another.  The new personality must be able
 337          * to handle the data in the current layout.
 338          * e.g. 2drive raid1 -> 2drive raid5
 339          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 340          * If the takeover succeeds, a new 'private' structure is returned.
 341          * This needs to be installed and then ->run used to activate the
 342          * array.
 343          */
 344         void *(*takeover) (mddev_t *mddev);
 345 };
 346
 347
 348 struct md_sysfs_entry {
 349         struct attribute attr;
 350         ssize_t (*show)(mddev_t *, char *);
 351         ssize_t (*store)(mddev_t *, const char *, size_t);
 352 };
 353
 354
 355 static inline char * mdname (mddev_t * mddev)
 356 {
 357         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 358 }
 359
 360 /*
 361  * iterates through some rdev ringlist. It's safe to remove the
 362  * current 'rdev'. Dont touch 'tmp' though.
 363  */
 364 #define rdev_for_each_list(rdev, tmp, head)                             \
 365         list_for_each_entry_safe(rdev, tmp, head, same_set)
 366
 367 /*
 368  * iterates through the 'same array disks' ringlist
 369  */
 370 #define rdev_for_each(rdev, tmp, mddev)                         \
 371         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 372
 373 #define rdev_for_each_rcu(rdev, mddev)                          \
 374         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 375
 376 typedef struct mdk_thread_s {
 377         void                    (*run) (mddev_t *mddev);
 378         mddev_t                 *mddev;
 379         wait_queue_head_t       wqueue;
 380         unsigned long           flags;
 381         struct task_struct      *tsk;
 382         unsigned long           timeout;
 383 } mdk_thread_t;
 384
 385 #define THREAD_WAKEUP  0
 386
 387 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 388 do {                                                                    \
 389         wait_queue_t __wait;                                            \
 390         init_waitqueue_entry(&__wait, current);                         \
 391                                                                         \
 392         add_wait_queue(&wq, &__wait);                                   \
 393         for (;;) {                                                      \
 394                 set_current_state(TASK_UNINTERRUPTIBLE);                \
 395                 if (condition)                                          \
 396                         break;                                          \
 397                 spin_unlock_irq(&lock);                                 \
 398                 cmd;                                                    \
 399                 schedule();                                             \
 400                 spin_lock_irq(&lock);                                   \
 401         }                                                               \
 402         current->state = TASK_RUNNING;                                  \
 403         remove_wait_queue(&wq, &__wait);                                \
 404 } while (0)
 405
 406 #define wait_event_lock_irq(wq, condition, lock, cmd)                   \
 407 do {                                                                    \
 408         if (condition)                                                  \
 409                 break;                                                  \
 410         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 411 } while (0)
 412
 413 static inline void safe_put_page(struct page *p)
 414 {
 415         if (p) put_page(p);
 416 }
 417
 418 extern int register_md_personality(struct mdk_personality *p);
 419 extern int unregister_md_personality(struct mdk_personality *p);
 420 extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
 421                                 mddev_t *mddev, const char *name);
 422 extern void md_unregister_thread(mdk_thread_t *thread);
 423 extern void md_wakeup_thread(mdk_thread_t *thread);
 424 extern void md_check_recovery(mddev_t *mddev);
 425 extern void md_write_start(mddev_t *mddev, struct bio *bi);
 426 extern void md_write_end(mddev_t *mddev);
 427 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 428 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 429
 430 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 431                            sector_t sector, int size, struct page *page);
 432 extern void md_super_wait(mddev_t *mddev);
 433 extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
 434                         struct page *page, int rw);
 435 extern void md_do_sync(mddev_t *mddev);
 436 extern void md_new_event(mddev_t *mddev);
 437 extern int md_allow_write(mddev_t *mddev);
 438 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 439 extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
 440
 441 #endif /* _MD_MD_H */