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 #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
 110 struct 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 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
 297 static 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
 304 static 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
 309 struct 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
 351 struct 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
 358 static 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
 379 typedef 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)                 \
 391 do {                                                                    \
 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)                   \
 410 do {                                                                    \
 411         if (condition)                                                  \
 412                 break;                                                  \
 413         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 414 } while (0)
 415
 416 static inline void safe_put_page(struct page *p)
 417 {
 418         if (p) put_page(p);
 419 }
 420
 421 extern int register_md_personality(struct mdk_personality *p);
 422 extern int unregister_md_personality(struct mdk_personality *p);
 423 extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
 424                                 mddev_t *mddev, const char *name);
 425 extern void md_unregister_thread(mdk_thread_t *thread);
 426 extern void md_wakeup_thread(mdk_thread_t *thread);
 427 extern void md_check_recovery(mddev_t *mddev);
 428 extern void md_write_start(mddev_t *mddev, struct bio *bi);
 429 extern void md_write_end(mddev_t *mddev);
 430 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 431 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 432
 433 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 434                            sector_t sector, int size, struct page *page);
 435 extern void md_super_wait(mddev_t *mddev);
 436 extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
 437                         struct page *page, int rw);
 438 extern void md_do_sync(mddev_t *mddev);
 439 extern void md_new_event(mddev_t *mddev);
 440 extern int md_allow_write(mddev_t *mddev);
 441 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 442 extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
 443 extern int md_check_no_bitmap(mddev_t *mddev);
 444 extern int md_integrity_register(mddev_t *mddev);
 445 void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 446
 447 #endif /* _MD_MD_H */