LXR linux/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
  29typedef struct mddev_s mddev_t;
  30typedef struct mdk_rdev_s mdk_rdev_t;
  31
  32/*
  33 * MD's 'extended' device
  34 */
  35struct 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#define StateChanged    9               /* Faulty or Blocked has changed during
  78                                         * interrupt, so it needs to be
  79                                         * notified by the thread */
  80        wait_queue_head_t blocked_wait;
  81
  82        int desc_nr;                    /* descriptor index in the superblock */
  83        int raid_disk;                  /* role of device in array */
  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        atomic_t        corrected_errors; /* number of corrected read errors,
 101                                           * for reporting to userspace and storing
 102                                           * in superblock.
 103                                           */
 104        struct work_struct del_work;    /* used for delayed sysfs removal */
 105
 106        struct sysfs_dirent *sysfs_state; /* handle for 'state'
 107                                           * sysfs entry */
 108};
 109
 110struct mddev_s
 111{
 112        void                            *private;
 113        struct mdk_personality          *pers;
 114        dev_t                           unit;
 115        int                             md_minor;
 116        struct list_head                disks;
 117        unsigned long                   flags;
 118#define MD_CHANGE_DEVS  0       /* Some device status has changed */
 119#define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 120#define MD_CHANGE_PENDING 2     /* superblock update in progress */
 121
 122        int                             suspended;
 123        atomic_t                        active_io;
 124        int                             ro;
 125
 126        struct gendisk                  *gendisk;
 127
 128        struct kobject                  kobj;
 129        int                             hold_active;
 130#define UNTIL_IOCTL     1
 131#define UNTIL_STOP      2
 132
 133        /* Superblock information */
 134        int                             major_version,
 135                                        minor_version,
 136                                        patch_version;
 137        int                             persistent;
 138        int                             external;       /* metadata is
 139                                                         * managed externally */
 140        char                            metadata_type[17]; /* externally set*/
 141        int                             chunk_sectors;
 142        time_t                          ctime, utime;
 143        int                             level, layout;
 144        char                            clevel[16];
 145        int                             raid_disks;
 146        int                             max_disks;
 147        sector_t                        dev_sectors;    /* used size of
 148                                                         * component devices */
 149        sector_t                        array_sectors; /* exported array size */
 150        int                             external_size; /* size managed
 151                                                        * externally */
 152        __u64                           events;
 153
 154        char                            uuid[16];
 155
 156        /* If the array is being reshaped, we need to record the
 157         * new shape and an indication of where we are up to.
 158         * This is written to the superblock.
 159         * If reshape_position is MaxSector, then no reshape is happening (yet).
 160         */
 161        sector_t                        reshape_position;
 162        int                             delta_disks, new_level, new_layout;
 163        int                             new_chunk_sectors;
 164
 165        struct mdk_thread_s             *thread;        /* management thread */
 166        struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
 167        sector_t                        curr_resync;    /* last block scheduled */
 168        /* As resync requests can complete out of order, we cannot easily track
 169         * how much resync has been completed.  So we occasionally pause until
 170         * everything completes, then set curr_resync_completed to curr_resync.
 171         * As such it may be well behind the real resync mark, but it is a value
 172         * we are certain of.
 173         */
 174        sector_t                        curr_resync_completed;
 175        unsigned long                   resync_mark;    /* a recent timestamp */
 176        sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 177        sector_t                        curr_mark_cnt; /* blocks scheduled now */
 178
 179        sector_t                        resync_max_sectors; /* may be set by personality */
 180
 181        sector_t                        resync_mismatches; /* count of sectors where
 182                                                            * parity/replica mismatch found
 183                                                            */
 184
 185        /* allow user-space to request suspension of IO to regions of the array */
 186        sector_t                        suspend_lo;
 187        sector_t                        suspend_hi;
 188        /* if zero, use the system-wide default */
 189        int                             sync_speed_min;
 190        int                             sync_speed_max;
 191
 192        /* resync even though the same disks are shared among md-devices */
 193        int                             parallel_resync;
 194
 195        int                             ok_start_degraded;
 196        /* recovery/resync flags 
 197         * NEEDED:   we might need to start a resync/recover
 198         * RUNNING:  a thread is running, or about to be started
 199         * SYNC:     actually doing a resync, not a recovery
 200         * RECOVER:  doing recovery, or need to try it.
 201         * INTR:     resync needs to be aborted for some reason
 202         * DONE:     thread is done and is waiting to be reaped
 203         * REQUEST:  user-space has requested a sync (used with SYNC)
 204         * CHECK:    user-space request for check-only, no repair
 205         * RESHAPE:  A reshape is happening
 206         *
 207         * If neither SYNC or RESHAPE are set, then it is a recovery.
 208         */
 209#define MD_RECOVERY_RUNNING     0
 210#define MD_RECOVERY_SYNC        1
 211#define MD_RECOVERY_RECOVER     2
 212#define MD_RECOVERY_INTR        3
 213#define MD_RECOVERY_DONE        4
 214#define MD_RECOVERY_NEEDED      5
 215#define MD_RECOVERY_REQUESTED   6
 216#define MD_RECOVERY_CHECK       7
 217#define MD_RECOVERY_RESHAPE     8
 218#define MD_RECOVERY_FROZEN      9
 219
 220        unsigned long                   recovery;
 221        int                             recovery_disabled; /* if we detect that recovery
 222                                                            * will always fail, set this
 223                                                            * so we don't loop trying */
 224
 225        int                             in_sync;        /* know to not need resync */
 226        /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 227         * that we are never stopping an array while it is open.
 228         * 'reconfig_mutex' protects all other reconfiguration.
 229         * These locks are separate due to conflicting interactions
 230         * with bdev->bd_mutex.
 231         * Lock ordering is:
 232         *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 233         *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 234         */
 235        struct mutex                    open_mutex;
 236        struct mutex                    reconfig_mutex;
 237        atomic_t                        active;         /* general refcount */
 238        atomic_t                        openers;        /* number of active opens */
 239
 240        int                             changed;        /* true if we might need to reread partition info */
 241        int                             degraded;       /* whether md should consider
 242                                                         * adding a spare
 243                                                         */
 244        int                             barriers_work;  /* initialised to true, cleared as soon
 245                                                         * as a barrier request to slave
 246                                                         * fails.  Only supported
 247                                                         */
 248        struct bio                      *biolist;       /* bios that need to be retried
 249                                                         * because BIO_RW_BARRIER is not supported
 250                                                         */
 251
 252        atomic_t                        recovery_active; /* blocks scheduled, but not written */
 253        wait_queue_head_t               recovery_wait;
 254        sector_t                        recovery_cp;
 255        sector_t                        resync_min;     /* user requested sync
 256                                                         * starts here */
 257        sector_t                        resync_max;     /* resync should pause
 258                                                         * when it gets here */
 259
 260        struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
 261                                                         * file in sysfs.
 262                                                         */
 263        struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
 264
 265        struct work_struct del_work;    /* used for delayed sysfs removal */
 266
 267        spinlock_t                      write_lock;
 268        wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 269        atomic_t                        pending_writes; /* number of active superblock writes */
 270
 271        unsigned int                    safemode;       /* if set, update "clean" superblock
 272                                                         * when no writes pending.
 273                                                         */ 
 274        unsigned int                    safemode_delay;
 275        struct timer_list               safemode_timer;
 276        atomic_t                        writes_pending; 
 277        struct request_queue            *queue; /* for plugging ... */
 278
 279        atomic_t                        write_behind; /* outstanding async IO */
 280        unsigned int                    max_write_behind; /* 0 = sync */
 281
 282        struct bitmap                   *bitmap; /* the bitmap for the device */
 283        struct file                     *bitmap_file; /* the bitmap file */
 284        long                            bitmap_offset; /* offset from superblock of
 285                                                        * start of bitmap. May be
 286                                                        * negative, but not '0'
 287                                                        */
 288        long                            default_bitmap_offset; /* this is the offset to use when
 289                                                                * hot-adding a bitmap.  It should
 290                                                                * eventually be settable by sysfs.
 291                                                                */
 292
 293        struct list_head                all_mddevs;
 294};
 295
 296
 297static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
 298{
 299        int faulty = test_bit(Faulty, &rdev->flags);
 300        if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
 301                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 302}
 303
 304static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 305{
 306        atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 307}
 308
 309struct mdk_personality
 310{
 311        char *name;
 312        int level;
 313        struct list_head list;
 314        struct module *owner;
 315        int (*make_request)(struct request_queue *q, struct bio *bio);
 316        int (*run)(mddev_t *mddev);
 317        int (*stop)(mddev_t *mddev);
 318        void (*status)(struct seq_file *seq, mddev_t *mddev);
 319        /* error_handler must set ->faulty and clear ->in_sync
 320         * if appropriate, and should abort recovery if needed 
 321         */
 322        void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
 323        int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
 324        int (*hot_remove_disk) (mddev_t *mddev, int number);
 325        int (*spare_active) (mddev_t *mddev);
 326        sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
 327        int (*resize) (mddev_t *mddev, sector_t sectors);
 328        sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
 329        int (*check_reshape) (mddev_t *mddev);
 330        int (*start_reshape) (mddev_t *mddev);
 331        void (*finish_reshape) (mddev_t *mddev);
 332        /* quiesce moves between quiescence states
 333         * 0 - fully active
 334         * 1 - no new requests allowed
 335         * others - reserved
 336         */
 337        void (*quiesce) (mddev_t *mddev, int state);
 338        /* takeover is used to transition an array from one
 339         * personality to another.  The new personality must be able
 340         * to handle the data in the current layout.
 341         * e.g. 2drive raid1 -> 2drive raid5
 342         *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 343         * If the takeover succeeds, a new 'private' structure is returned.
 344         * This needs to be installed and then ->run used to activate the
 345         * array.
 346         */
 347        void *(*takeover) (mddev_t *mddev);
 348};
 349
 350
 351struct md_sysfs_entry {
 352        struct attribute attr;
 353        ssize_t (*show)(mddev_t *, char *);
 354        ssize_t (*store)(mddev_t *, const char *, size_t);
 355};
 356
 357
 358static inline char * mdname (mddev_t * mddev)
 359{
 360        return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 361}
 362
 363/*
 364 * iterates through some rdev ringlist. It's safe to remove the
 365 * current 'rdev'. Dont touch 'tmp' though.
 366 */
 367#define rdev_for_each_list(rdev, tmp, head)                             \
 368        list_for_each_entry_safe(rdev, tmp, head, same_set)
 369
 370/*
 371 * iterates through the 'same array disks' ringlist
 372 */
 373#define rdev_for_each(rdev, tmp, mddev)                         \
 374        list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 375
 376#define rdev_for_each_rcu(rdev, mddev)                          \
 377        list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 378
 379typedef struct mdk_thread_s {
 380        void                    (*run) (mddev_t *mddev);
 381        mddev_t                 *mddev;
 382        wait_queue_head_t       wqueue;
 383        unsigned long           flags;
 384        struct task_struct      *tsk;
 385        unsigned long           timeout;
 386} mdk_thread_t;
 387
 388#define THREAD_WAKEUP  0
 389
 390#define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 391do {                                                                    \
 392        wait_queue_t __wait;                                            \
 393        init_waitqueue_entry(&__wait, current);                         \
 394                                                                        \
 395        add_wait_queue(&wq, &__wait);                                   \
 396        for (;;) {                                                      \
 397                set_current_state(TASK_UNINTERRUPTIBLE);                \
 398                if (condition)                                          \
 399                        break;                                          \
 400                spin_unlock_irq(&lock);                                 \
 401                cmd;                                                    \
 402                schedule();                                             \
 403                spin_lock_irq(&lock);                                   \
 404        }                                                               \
 405        current->state = TASK_RUNNING;                                  \
 406        remove_wait_queue(&wq, &__wait);                                \
 407} while (0)
 408
 409#define wait_event_lock_irq(wq, condition, lock, cmd)                   \
 410do {                                                                    \
 411        if (condition)                                                  \
 412                break;                                                  \
 413        __wait_event_lock_irq(wq, condition, lock, cmd);                \
 414} while (0)
 415
 416static inline void safe_put_page(struct page *p)
 417{
 418        if (p) put_page(p);
 419}
 420
 421extern int register_md_personality(struct mdk_personality *p);
 422extern int unregister_md_personality(struct mdk_personality *p);
 423extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
 424                                mddev_t *mddev, const char *name);
 425extern void md_unregister_thread(mdk_thread_t *thread);
 426extern void md_wakeup_thread(mdk_thread_t *thread);
 427extern void md_check_recovery(mddev_t *mddev);
 428extern void md_write_start(mddev_t *mddev, struct bio *bi);
 429extern void md_write_end(mddev_t *mddev);
 430extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 431extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 432
 433extern int mddev_congested(mddev_t *mddev, int bits);
 434extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 435                           sector_t sector, int size, struct page *page);
 436extern void md_super_wait(mddev_t *mddev);
 437extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
 438                        struct page *page, int rw);
 439extern void md_do_sync(mddev_t *mddev);
 440extern void md_new_event(mddev_t *mddev);
 441extern int md_allow_write(mddev_t *mddev);
 442extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 443extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
 444extern int md_check_no_bitmap(mddev_t *mddev);
 445extern int md_integrity_register(mddev_t *mddev);
 446void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 447
 448#endif /* _MD_MD_H */
 449