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         /*
  44          * If meta_bdev is non-NULL, it means that a separate device is
  45          * being used to store the metadata (superblock/bitmap) which
  46          * would otherwise be contained on the same device as the data (bdev).
  47          */
  48         struct block_device *meta_bdev;
  49         struct block_device *bdev;      /* block device handle */
  50
  51         struct page     *sb_page;
  52         int             sb_loaded;
  53         __u64           sb_events;
  54         sector_t        data_offset;    /* start of data in array */
  55         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
  56         int             sb_size;        /* bytes in the superblock */
  57         int             preferred_minor;        /* autorun support */
  58
  59         struct kobject  kobj;
  60
  61         /* A device can be in one of three states based on two flags:
  62          * Not working:   faulty==1 in_sync==0
  63          * Fully working: faulty==0 in_sync==1
  64          * Working, but not
  65          * in sync with array
  66          *                faulty==0 in_sync==0
  67          *
  68          * It can never have faulty==1, in_sync==1
  69          * This reduces the burden of testing multiple flags in many cases
  70          */
  71
  72         unsigned long   flags;
  73 #define Faulty          1               /* device is known to have a fault */
  74 #define In_sync         2               /* device is in_sync with rest of array */
  75 #define WriteMostly     4               /* Avoid reading if at all possible */
  76 #define AutoDetected    7               /* added by auto-detect */
  77 #define Blocked         8               /* An error occurred on an externally
  78                                          * managed array, don't allow writes
  79                                          * until it is cleared */
  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 new_raid_disk;              /* role that the device will have in
  85                                          * the array after a level-change completes.
  86                                          */
  87         int saved_raid_disk;            /* role that device used to have in the
  88                                          * array and could again if we did a partial
  89                                          * resync from the bitmap
  90                                          */
  91         sector_t        recovery_offset;/* If this device has been partially
  92                                          * recovered, this is where we were
  93                                          * up to.
  94                                          */
  95
  96         atomic_t        nr_pending;     /* number of pending requests.
  97                                          * only maintained for arrays that
  98                                          * support hot removal
  99                                          */
 100         atomic_t        read_errors;    /* number of consecutive read errors that
 101                                          * we have tried to ignore.
 102                                          */
 103         struct timespec last_read_error;        /* monotonic time since our
 104                                                  * last read error
 105                                                  */
 106         atomic_t        corrected_errors; /* number of corrected read errors,
 107                                            * for reporting to userspace and storing
 108                                            * in superblock.
 109                                            */
 110         struct work_struct del_work;    /* used for delayed sysfs removal */
 111
 112         struct sysfs_dirent *sysfs_state; /* handle for 'state'
 113                                            * sysfs entry */
 114 };
 115
 116 struct mddev_s
 117 {
 118         void                            *private;
 119         struct mdk_personality          *pers;
 120         dev_t                           unit;
 121         int                             md_minor;
 122         struct list_head                disks;
 123         unsigned long                   flags;
 124 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
 125 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 126 #define MD_CHANGE_PENDING 2     /* switch from 'clean' to 'active' in progress */
 127
 128         int                             suspended;
 129         atomic_t                        active_io;
 130         int                             ro;
 131         int                             sysfs_active; /* set when sysfs deletes
 132                                                        * are happening, so run/
 133                                                        * takeover/stop are not safe
 134                                                        */
 135         int                             ready; /* See when safe to pass
 136                                                 * IO requests down */
 137         struct gendisk                  *gendisk;
 138
 139         struct kobject                  kobj;
 140         int                             hold_active;
 141 #define UNTIL_IOCTL     1
 142 #define UNTIL_STOP      2
 143
 144         /* Superblock information */
 145         int                             major_version,
 146                                         minor_version,
 147                                         patch_version;
 148         int                             persistent;
 149         int                             external;       /* metadata is
 150                                                          * managed externally */
 151         char                            metadata_type[17]; /* externally set*/
 152         int                             chunk_sectors;
 153         time_t                          ctime, utime;
 154         int                             level, layout;
 155         char                            clevel[16];
 156         int                             raid_disks;
 157         int                             max_disks;
 158         sector_t                        dev_sectors;    /* used size of
 159                                                          * component devices */
 160         sector_t                        array_sectors; /* exported array size */
 161         int                             external_size; /* size managed
 162                                                         * externally */
 163         __u64                           events;
 164         /* If the last 'event' was simply a clean->dirty transition, and
 165          * we didn't write it to the spares, then it is safe and simple
 166          * to just decrement the event count on a dirty->clean transition.
 167          * So we record that possibility here.
 168          */
 169         int                             can_decrease_events;
 170
 171         char                            uuid[16];
 172
 173         /* If the array is being reshaped, we need to record the
 174          * new shape and an indication of where we are up to.
 175          * This is written to the superblock.
 176          * If reshape_position is MaxSector, then no reshape is happening (yet).
 177          */
 178         sector_t                        reshape_position;
 179         int                             delta_disks, new_level, new_layout;
 180         int                             new_chunk_sectors;
 181
 182         struct mdk_thread_s             *thread;        /* management thread */
 183         struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
 184         sector_t                        curr_resync;    /* last block scheduled */
 185         /* As resync requests can complete out of order, we cannot easily track
 186          * how much resync has been completed.  So we occasionally pause until
 187          * everything completes, then set curr_resync_completed to curr_resync.
 188          * As such it may be well behind the real resync mark, but it is a value
 189          * we are certain of.
 190          */
 191         sector_t                        curr_resync_completed;
 192         unsigned long                   resync_mark;    /* a recent timestamp */
 193         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
 194         sector_t                        curr_mark_cnt; /* blocks scheduled now */
 195
 196         sector_t                        resync_max_sectors; /* may be set by personality */
 197
 198         sector_t                        resync_mismatches; /* count of sectors where
 199                                                             * parity/replica mismatch found
 200                                                             */
 201
 202         /* allow user-space to request suspension of IO to regions of the array */
 203         sector_t                        suspend_lo;
 204         sector_t                        suspend_hi;
 205         /* if zero, use the system-wide default */
 206         int                             sync_speed_min;
 207         int                             sync_speed_max;
 208
 209         /* resync even though the same disks are shared among md-devices */
 210         int                             parallel_resync;
 211
 212         int                             ok_start_degraded;
 213         /* recovery/resync flags
 214          * NEEDED:   we might need to start a resync/recover
 215          * RUNNING:  a thread is running, or about to be started
 216          * SYNC:     actually doing a resync, not a recovery
 217          * RECOVER:  doing recovery, or need to try it.
 218          * INTR:     resync needs to be aborted for some reason
 219          * DONE:     thread is done and is waiting to be reaped
 220          * REQUEST:  user-space has requested a sync (used with SYNC)
 221          * CHECK:    user-space request for check-only, no repair
 222          * RESHAPE:  A reshape is happening
 223          *
 224          * If neither SYNC or RESHAPE are set, then it is a recovery.
 225          */
 226 #define MD_RECOVERY_RUNNING     0
 227 #define MD_RECOVERY_SYNC        1
 228 #define MD_RECOVERY_RECOVER     2
 229 #define MD_RECOVERY_INTR        3
 230 #define MD_RECOVERY_DONE        4
 231 #define MD_RECOVERY_NEEDED      5
 232 #define MD_RECOVERY_REQUESTED   6
 233 #define MD_RECOVERY_CHECK       7
 234 #define MD_RECOVERY_RESHAPE     8
 235 #define MD_RECOVERY_FROZEN      9
 236
 237         unsigned long                   recovery;
 238         int                             recovery_disabled; /* if we detect that recovery
 239                                                             * will always fail, set this
 240                                                             * so we don't loop trying */
 241
 242         int                             in_sync;        /* know to not need resync */
 243         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
 244          * that we are never stopping an array while it is open.
 245          * 'reconfig_mutex' protects all other reconfiguration.
 246          * These locks are separate due to conflicting interactions
 247          * with bdev->bd_mutex.
 248          * Lock ordering is:
 249          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
 250          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
 251          */
 252         struct mutex                    open_mutex;
 253         struct mutex                    reconfig_mutex;
 254         atomic_t                        active;         /* general refcount */
 255         atomic_t                        openers;        /* number of active opens */
 256
 257         int                             changed;        /* True if we might need to
 258                                                          * reread partition info */
 259         int                             degraded;       /* whether md should consider
 260                                                          * adding a spare
 261                                                          */
 262
 263         atomic_t                        recovery_active; /* blocks scheduled, but not written */
 264         wait_queue_head_t               recovery_wait;
 265         sector_t                        recovery_cp;
 266         sector_t                        resync_min;     /* user requested sync
 267                                                          * starts here */
 268         sector_t                        resync_max;     /* resync should pause
 269                                                          * when it gets here */
 270
 271         struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
 272                                                          * file in sysfs.
 273                                                          */
 274         struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
 275
 276         struct work_struct del_work;    /* used for delayed sysfs removal */
 277
 278         spinlock_t                      write_lock;
 279         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
 280         atomic_t                        pending_writes; /* number of active superblock writes */
 281
 282         unsigned int                    safemode;       /* if set, update "clean" superblock
 283                                                          * when no writes pending.
 284                                                          */
 285         unsigned int                    safemode_delay;
 286         struct timer_list               safemode_timer;
 287         atomic_t                        writes_pending;
 288         struct request_queue            *queue; /* for plugging ... */
 289
 290         struct bitmap                   *bitmap; /* the bitmap for the device */
 291         struct {
 292                 struct file             *file; /* the bitmap file */
 293                 loff_t                  offset; /* offset from superblock of
 294                                                  * start of bitmap. May be
 295                                                  * negative, but not '0'
 296                                                  * For external metadata, offset
 297                                                  * from start of device.
 298                                                  */
 299                 loff_t                  default_offset; /* this is the offset to use when
 300                                                          * hot-adding a bitmap.  It should
 301                                                          * eventually be settable by sysfs.
 302                                                          */
 303                 /* When md is serving under dm, it might use a
 304                  * dirty_log to store the bits.
 305                  */
 306                 struct dm_dirty_log *log;
 307
 308                 struct mutex            mutex;
 309                 unsigned long           chunksize;
 310                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
 311                 unsigned long           max_write_behind; /* write-behind mode */
 312                 int                     external;
 313         } bitmap_info;
 314
 315         atomic_t                        max_corr_read_errors; /* max read retries */
 316         struct list_head                all_mddevs;
 317
 318         struct attribute_group          *to_remove;
 319
 320         struct bio_set                  *bio_set;
 321
 322         /* Generic flush handling.
 323          * The last to finish preflush schedules a worker to submit
 324          * the rest of the request (without the REQ_FLUSH flag).
 325          */
 326         struct bio *flush_bio;
 327         atomic_t flush_pending;
 328         struct work_struct flush_work;
 329         struct work_struct event_work;  /* used by dm to report failure event */
 330 };
 331
 332
 333 static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
 334 {
 335         int faulty = test_bit(Faulty, &rdev->flags);
 336         if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
 337                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 338 }
 339
 340 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 341 {
 342         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
 343 }
 344
 345 struct mdk_personality
 346 {
 347         char *name;
 348         int level;
 349         struct list_head list;
 350         struct module *owner;
 351         int (*make_request)(mddev_t *mddev, struct bio *bio);
 352         int (*run)(mddev_t *mddev);
 353         int (*stop)(mddev_t *mddev);
 354         void (*status)(struct seq_file *seq, mddev_t *mddev);
 355         /* error_handler must set ->faulty and clear ->in_sync
 356          * if appropriate, and should abort recovery if needed
 357          */
 358         void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
 359         int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
 360         int (*hot_remove_disk) (mddev_t *mddev, int number);
 361         int (*spare_active) (mddev_t *mddev);
 362         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
 363         int (*resize) (mddev_t *mddev, sector_t sectors);
 364         sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
 365         int (*check_reshape) (mddev_t *mddev);
 366         int (*start_reshape) (mddev_t *mddev);
 367         void (*finish_reshape) (mddev_t *mddev);
 368         /* quiesce moves between quiescence states
 369          * 0 - fully active
 370          * 1 - no new requests allowed
 371          * others - reserved
 372          */
 373         void (*quiesce) (mddev_t *mddev, int state);
 374         /* takeover is used to transition an array from one
 375          * personality to another.  The new personality must be able
 376          * to handle the data in the current layout.
 377          * e.g. 2drive raid1 -> 2drive raid5
 378          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
 379          * If the takeover succeeds, a new 'private' structure is returned.
 380          * This needs to be installed and then ->run used to activate the
 381          * array.
 382          */
 383         void *(*takeover) (mddev_t *mddev);
 384 };
 385
 386
 387 struct md_sysfs_entry {
 388         struct attribute attr;
 389         ssize_t (*show)(mddev_t *, char *);
 390         ssize_t (*store)(mddev_t *, const char *, size_t);
 391 };
 392 extern struct attribute_group md_bitmap_group;
 393
 394 static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
 395 {
 396         if (sd)
 397                 return sysfs_get_dirent(sd, NULL, name);
 398         return sd;
 399 }
 400 static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
 401 {
 402         if (sd)
 403                 sysfs_notify_dirent(sd);
 404 }
 405
 406 static inline char * mdname (mddev_t * mddev)
 407 {
 408         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
 409 }
 410
 411 /*
 412  * iterates through some rdev ringlist. It's safe to remove the
 413  * current 'rdev'. Dont touch 'tmp' though.
 414  */
 415 #define rdev_for_each_list(rdev, tmp, head)                             \
 416         list_for_each_entry_safe(rdev, tmp, head, same_set)
 417
 418 /*
 419  * iterates through the 'same array disks' ringlist
 420  */
 421 #define rdev_for_each(rdev, tmp, mddev)                         \
 422         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 423
 424 #define rdev_for_each_rcu(rdev, mddev)                          \
 425         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
 426
 427 typedef struct mdk_thread_s {
 428         void                    (*run) (mddev_t *mddev);
 429         mddev_t                 *mddev;
 430         wait_queue_head_t       wqueue;
 431         unsigned long           flags;
 432         struct task_struct      *tsk;
 433         unsigned long           timeout;
 434 } mdk_thread_t;
 435
 436 #define THREAD_WAKEUP  0
 437
 438 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
 439 do {                                                                    \
 440         wait_queue_t __wait;                                            \
 441         init_waitqueue_entry(&__wait, current);                         \
 442                                                                         \
 443         add_wait_queue(&wq, &__wait);                                   \
 444         for (;;) {                                                      \
 445                 set_current_state(TASK_UNINTERRUPTIBLE);                \
 446                 if (condition)                                          \
 447                         break;                                          \
 448                 spin_unlock_irq(&lock);                                 \
 449                 cmd;                                                    \
 450                 schedule();                                             \
 451                 spin_lock_irq(&lock);                                   \
 452         }                                                               \
 453         current->state = TASK_RUNNING;                                  \
 454         remove_wait_queue(&wq, &__wait);                                \
 455 } while (0)
 456
 457 #define wait_event_lock_irq(wq, condition, lock, cmd)                   \
 458 do {                                                                    \
 459         if (condition)                                                  \
 460                 break;                                                  \
 461         __wait_event_lock_irq(wq, condition, lock, cmd);                \
 462 } while (0)
 463
 464 static inline void safe_put_page(struct page *p)
 465 {
 466         if (p) put_page(p);
 467 }
 468
 469 extern int register_md_personality(struct mdk_personality *p);
 470 extern int unregister_md_personality(struct mdk_personality *p);
 471 extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
 472                                 mddev_t *mddev, const char *name);
 473 extern void md_unregister_thread(mdk_thread_t *thread);
 474 extern void md_wakeup_thread(mdk_thread_t *thread);
 475 extern void md_check_recovery(mddev_t *mddev);
 476 extern void md_write_start(mddev_t *mddev, struct bio *bi);
 477 extern void md_write_end(mddev_t *mddev);
 478 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 479 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 480
 481 extern int mddev_congested(mddev_t *mddev, int bits);
 482 extern void md_flush_request(mddev_t *mddev, struct bio *bio);
 483 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 484                            sector_t sector, int size, struct page *page);
 485 extern void md_super_wait(mddev_t *mddev);
 486 extern int sync_page_io(mdk_rdev_t *rdev, sector_t sector, int size,
 487                         struct page *page, int rw, bool metadata_op);
 488 extern void md_do_sync(mddev_t *mddev);
 489 extern void md_new_event(mddev_t *mddev);
 490 extern int md_allow_write(mddev_t *mddev);
 491 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 492 extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
 493 extern int md_check_no_bitmap(mddev_t *mddev);
 494 extern int md_integrity_register(mddev_t *mddev);
 495 extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
 496 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
 497 extern void restore_bitmap_write_access(struct file *file);
 498
 499 extern void mddev_init(mddev_t *mddev);
 500 extern int md_run(mddev_t *mddev);
 501 extern void md_stop(mddev_t *mddev);
 502 extern void md_stop_writes(mddev_t *mddev);
 503 extern void md_rdev_init(mdk_rdev_t *rdev);
 504
 505 extern void mddev_suspend(mddev_t *mddev);
 506 extern void mddev_resume(mddev_t *mddev);
 507 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
 508                                    mddev_t *mddev);
 509 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
 510                                    mddev_t *mddev);
 511 #endif /* _MD_MD_H */