2 md.h : kernel internal structure of the Linux MD driver
3 Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
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)
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.
18 #include <linux/blkdev.h>
19 #include <linux/kobject.h>
20 #include <linux/list.h>
22 #include <linux/mutex.h>
23 #include <linux/timer.h>
24 #include <linux/wait.h>
25 #include <linux/workqueue.h>
27 #define MaxSector (~(sector_t)0)
29 /* Bad block numbers are stored sorted in a single page.
30 * 64bits is used for each block or extent.
31 * 54 bits are sector number, 9 bits are extent size,
32 * 1 bit is an 'acknowledged' flag.
34 #define MD_MAX_BADBLOCKS (PAGE_SIZE/8)
37 * MD's 'extended' device
40 struct list_head same_set; /* RAID devices within the same set */
42 sector_t sectors; /* Device size (in 512bytes sectors) */
43 struct mddev *mddev; /* RAID array if running */
44 int last_events; /* IO event timestamp */
47 * If meta_bdev is non-NULL, it means that a separate device is
48 * being used to store the metadata (superblock/bitmap) which
49 * would otherwise be contained on the same device as the data (bdev).
51 struct block_device *meta_bdev;
52 struct block_device *bdev; /* block device handle */
54 struct page *sb_page, *bb_page;
57 sector_t data_offset; /* start of data in array */
58 sector_t new_data_offset;/* only relevant while reshaping */
59 sector_t sb_start; /* offset of the super block (in 512byte sectors) */
60 int sb_size; /* bytes in the superblock */
61 int preferred_minor; /* autorun support */
65 /* A device can be in one of three states based on two flags:
66 * Not working: faulty==1 in_sync==0
67 * Fully working: faulty==0 in_sync==1
70 * faulty==0 in_sync==0
72 * It can never have faulty==1, in_sync==1
73 * This reduces the burden of testing multiple flags in many cases
76 unsigned long flags; /* bit set of 'enum flag_bits' bits. */
77 wait_queue_head_t blocked_wait;
79 int desc_nr; /* descriptor index in the superblock */
80 int raid_disk; /* role of device in array */
81 int new_raid_disk; /* role that the device will have in
82 * the array after a level-change completes.
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
88 sector_t recovery_offset;/* If this device has been partially
89 * recovered, this is where we were
93 atomic_t nr_pending; /* number of pending requests.
94 * only maintained for arrays that
97 atomic_t read_errors; /* number of consecutive read errors that
98 * we have tried to ignore.
100 struct timespec last_read_error; /* monotonic time since our
103 atomic_t corrected_errors; /* number of corrected read errors,
104 * for reporting to userspace and storing
107 struct work_struct del_work; /* used for delayed sysfs removal */
109 struct sysfs_dirent *sysfs_state; /* handle for 'state'
113 int count; /* count of bad blocks */
114 int unacked_exist; /* there probably are unacknowledged
115 * bad blocks. This is only cleared
116 * when a read discovers none
118 int shift; /* shift from sectors to block size
119 * a -ve shift means badblocks are
121 u64 *page; /* badblock list */
126 sector_t size; /* in sectors */
130 Faulty, /* device is known to have a fault */
131 In_sync, /* device is in_sync with rest of array */
132 Bitmap_sync, /* ..actually, not quite In_sync. Need a
133 * bitmap-based recovery to get fully in sync
135 Unmerged, /* device is being added to array and should
136 * be considerred for bvec_merge_fn but not
139 WriteMostly, /* Avoid reading if at all possible */
140 AutoDetected, /* added by auto-detect */
141 Blocked, /* An error occurred but has not yet
142 * been acknowledged by the metadata
143 * handler, so don't allow writes
144 * until it is cleared */
145 WriteErrorSeen, /* A write error has been seen on this
148 FaultRecorded, /* Intermediate state for clearing
149 * Blocked. The Fault is/will-be
150 * recorded in the metadata, but that
151 * metadata hasn't been stored safely
154 BlockedBadBlocks, /* A writer is blocked because they
155 * found an unacknowledged bad-block.
156 * This can safely be cleared at any
157 * time, and the writer will re-check.
158 * It may be set at any time, and at
159 * worst the writer will timeout and
160 * re-check. So setting it as
161 * accurately as possible is good, but
162 * not absolutely critical.
164 WantReplacement, /* This device is a candidate to be
165 * hot-replaced, either because it has
166 * reported some faults, or because
167 * of explicit request.
169 Replacement, /* This device is a replacement for
170 * a want_replacement device with same
175 #define BB_LEN_MASK (0x00000000000001FFULL)
176 #define BB_OFFSET_MASK (0x7FFFFFFFFFFFFE00ULL)
177 #define BB_ACK_MASK (0x8000000000000000ULL)
178 #define BB_MAX_LEN 512
179 #define BB_OFFSET(x) (((x) & BB_OFFSET_MASK) >> 9)
180 #define BB_LEN(x) (((x) & BB_LEN_MASK) + 1)
181 #define BB_ACK(x) (!!((x) & BB_ACK_MASK))
182 #define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
184 extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
185 sector_t *first_bad, int *bad_sectors);
186 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
187 sector_t *first_bad, int *bad_sectors)
189 if (unlikely(rdev->badblocks.count)) {
190 int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
192 first_bad, bad_sectors);
194 *first_bad -= rdev->data_offset;
199 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
201 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
203 extern void md_ack_all_badblocks(struct badblocks *bb);
207 struct md_personality *pers;
210 struct list_head disks;
212 #define MD_CHANGE_DEVS 0 /* Some device status has changed */
213 #define MD_CHANGE_CLEAN 1 /* transition to or from 'clean' */
214 #define MD_CHANGE_PENDING 2 /* switch from 'clean' to 'active' in progress */
215 #define MD_ARRAY_FIRST_USE 3 /* First use of array, needs initialization */
220 int sysfs_active; /* set when sysfs deletes
221 * are happening, so run/
222 * takeover/stop are not safe
224 int ready; /* See when safe to pass
225 * IO requests down */
226 struct gendisk *gendisk;
230 #define UNTIL_IOCTL 1
233 /* Superblock information */
238 int external; /* metadata is
239 * managed externally */
240 char metadata_type[17]; /* externally set*/
247 sector_t dev_sectors; /* used size of
248 * component devices */
249 sector_t array_sectors; /* exported array size */
250 int external_size; /* size managed
253 /* If the last 'event' was simply a clean->dirty transition, and
254 * we didn't write it to the spares, then it is safe and simple
255 * to just decrement the event count on a dirty->clean transition.
256 * So we record that possibility here.
258 int can_decrease_events;
262 /* If the array is being reshaped, we need to record the
263 * new shape and an indication of where we are up to.
264 * This is written to the superblock.
265 * If reshape_position is MaxSector, then no reshape is happening (yet).
267 sector_t reshape_position;
268 int delta_disks, new_level, new_layout;
269 int new_chunk_sectors;
270 int reshape_backwards;
272 struct md_thread *thread; /* management thread */
273 struct md_thread *sync_thread; /* doing resync or reconstruct */
274 sector_t curr_resync; /* last block scheduled */
275 /* As resync requests can complete out of order, we cannot easily track
276 * how much resync has been completed. So we occasionally pause until
277 * everything completes, then set curr_resync_completed to curr_resync.
278 * As such it may be well behind the real resync mark, but it is a value
281 sector_t curr_resync_completed;
282 unsigned long resync_mark; /* a recent timestamp */
283 sector_t resync_mark_cnt;/* blocks written at resync_mark */
284 sector_t curr_mark_cnt; /* blocks scheduled now */
286 sector_t resync_max_sectors; /* may be set by personality */
288 atomic64_t resync_mismatches; /* count of sectors where
289 * parity/replica mismatch found
292 /* allow user-space to request suspension of IO to regions of the array */
295 /* if zero, use the system-wide default */
299 /* resync even though the same disks are shared among md-devices */
302 int ok_start_degraded;
303 /* recovery/resync flags
304 * NEEDED: we might need to start a resync/recover
305 * RUNNING: a thread is running, or about to be started
306 * SYNC: actually doing a resync, not a recovery
307 * RECOVER: doing recovery, or need to try it.
308 * INTR: resync needs to be aborted for some reason
309 * DONE: thread is done and is waiting to be reaped
310 * REQUEST: user-space has requested a sync (used with SYNC)
311 * CHECK: user-space request for check-only, no repair
312 * RESHAPE: A reshape is happening
313 * ERROR: sync-action interrupted because io-error
315 * If neither SYNC or RESHAPE are set, then it is a recovery.
317 #define MD_RECOVERY_RUNNING 0
318 #define MD_RECOVERY_SYNC 1
319 #define MD_RECOVERY_RECOVER 2
320 #define MD_RECOVERY_INTR 3
321 #define MD_RECOVERY_DONE 4
322 #define MD_RECOVERY_NEEDED 5
323 #define MD_RECOVERY_REQUESTED 6
324 #define MD_RECOVERY_CHECK 7
325 #define MD_RECOVERY_RESHAPE 8
326 #define MD_RECOVERY_FROZEN 9
327 #define MD_RECOVERY_ERROR 10
329 unsigned long recovery;
330 /* If a RAID personality determines that recovery (of a particular
331 * device) will fail due to a read error on the source device, it
332 * takes a copy of this number and does not attempt recovery again
333 * until this number changes.
335 int recovery_disabled;
337 int in_sync; /* know to not need resync */
338 /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
339 * that we are never stopping an array while it is open.
340 * 'reconfig_mutex' protects all other reconfiguration.
341 * These locks are separate due to conflicting interactions
342 * with bdev->bd_mutex.
344 * reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
345 * bd_mutex -> open_mutex: e.g. __blkdev_get -> md_open
347 struct mutex open_mutex;
348 struct mutex reconfig_mutex;
349 atomic_t active; /* general refcount */
350 atomic_t openers; /* number of active opens */
352 int changed; /* True if we might need to
353 * reread partition info */
354 int degraded; /* whether md should consider
357 int merge_check_needed; /* at least one
362 atomic_t recovery_active; /* blocks scheduled, but not written */
363 wait_queue_head_t recovery_wait;
364 sector_t recovery_cp;
365 sector_t resync_min; /* user requested sync
367 sector_t resync_max; /* resync should pause
368 * when it gets here */
370 struct sysfs_dirent *sysfs_state; /* handle for 'array_state'
373 struct sysfs_dirent *sysfs_action; /* handle for 'sync_action' */
375 struct work_struct del_work; /* used for delayed sysfs removal */
377 spinlock_t write_lock;
378 wait_queue_head_t sb_wait; /* for waiting on superblock updates */
379 atomic_t pending_writes; /* number of active superblock writes */
381 unsigned int safemode; /* if set, update "clean" superblock
382 * when no writes pending.
384 unsigned int safemode_delay;
385 struct timer_list safemode_timer;
386 atomic_t writes_pending;
387 struct request_queue *queue; /* for plugging ... */
389 struct bitmap *bitmap; /* the bitmap for the device */
391 struct file *file; /* the bitmap file */
392 loff_t offset; /* offset from superblock of
393 * start of bitmap. May be
394 * negative, but not '0'
395 * For external metadata, offset
396 * from start of device.
398 unsigned long space; /* space available at this offset */
399 loff_t default_offset; /* this is the offset to use when
400 * hot-adding a bitmap. It should
401 * eventually be settable by sysfs.
403 unsigned long default_space; /* space available at
406 unsigned long chunksize;
407 unsigned long daemon_sleep; /* how many jiffies between updates? */
408 unsigned long max_write_behind; /* write-behind mode */
412 atomic_t max_corr_read_errors; /* max read retries */
413 struct list_head all_mddevs;
415 struct attribute_group *to_remove;
417 struct bio_set *bio_set;
419 /* Generic flush handling.
420 * The last to finish preflush schedules a worker to submit
421 * the rest of the request (without the REQ_FLUSH flag).
423 struct bio *flush_bio;
424 atomic_t flush_pending;
425 struct work_struct flush_work;
426 struct work_struct event_work; /* used by dm to report failure event */
427 void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
431 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
433 int faulty = test_bit(Faulty, &rdev->flags);
434 if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
435 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
438 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
440 atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
443 struct md_personality
447 struct list_head list;
448 struct module *owner;
449 void (*make_request)(struct mddev *mddev, struct bio *bio);
450 int (*run)(struct mddev *mddev);
451 int (*stop)(struct mddev *mddev);
452 void (*status)(struct seq_file *seq, struct mddev *mddev);
453 /* error_handler must set ->faulty and clear ->in_sync
454 * if appropriate, and should abort recovery if needed
456 void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
457 int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
458 int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
459 int (*spare_active) (struct mddev *mddev);
460 sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster);
461 int (*resize) (struct mddev *mddev, sector_t sectors);
462 sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
463 int (*check_reshape) (struct mddev *mddev);
464 int (*start_reshape) (struct mddev *mddev);
465 void (*finish_reshape) (struct mddev *mddev);
466 /* quiesce moves between quiescence states
468 * 1 - no new requests allowed
471 void (*quiesce) (struct mddev *mddev, int state);
472 /* takeover is used to transition an array from one
473 * personality to another. The new personality must be able
474 * to handle the data in the current layout.
475 * e.g. 2drive raid1 -> 2drive raid5
476 * ndrive raid5 -> degraded n+1drive raid6 with special layout
477 * If the takeover succeeds, a new 'private' structure is returned.
478 * This needs to be installed and then ->run used to activate the
481 void *(*takeover) (struct mddev *mddev);
485 struct md_sysfs_entry {
486 struct attribute attr;
487 ssize_t (*show)(struct mddev *, char *);
488 ssize_t (*store)(struct mddev *, const char *, size_t);
490 extern struct attribute_group md_bitmap_group;
492 static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
495 return sysfs_get_dirent(sd, NULL, name);
498 static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
501 sysfs_notify_dirent(sd);
504 static inline char * mdname (struct mddev * mddev)
506 return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
509 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
512 if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
513 sprintf(nm, "rd%d", rdev->raid_disk);
514 return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
519 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
522 if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
523 sprintf(nm, "rd%d", rdev->raid_disk);
524 sysfs_remove_link(&mddev->kobj, nm);
529 * iterates through some rdev ringlist. It's safe to remove the
530 * current 'rdev'. Dont touch 'tmp' though.
532 #define rdev_for_each_list(rdev, tmp, head) \
533 list_for_each_entry_safe(rdev, tmp, head, same_set)
536 * iterates through the 'same array disks' ringlist
538 #define rdev_for_each(rdev, mddev) \
539 list_for_each_entry(rdev, &((mddev)->disks), same_set)
541 #define rdev_for_each_safe(rdev, tmp, mddev) \
542 list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
544 #define rdev_for_each_rcu(rdev, mddev) \
545 list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
548 void (*run) (struct md_thread *thread);
550 wait_queue_head_t wqueue;
552 struct task_struct *tsk;
553 unsigned long timeout;
557 #define THREAD_WAKEUP 0
559 static inline void safe_put_page(struct page *p)
564 extern int register_md_personality(struct md_personality *p);
565 extern int unregister_md_personality(struct md_personality *p);
566 extern struct md_thread *md_register_thread(
567 void (*run)(struct md_thread *thread),
570 extern void md_unregister_thread(struct md_thread **threadp);
571 extern void md_wakeup_thread(struct md_thread *thread);
572 extern void md_check_recovery(struct mddev *mddev);
573 extern void md_reap_sync_thread(struct mddev *mddev);
574 extern void md_write_start(struct mddev *mddev, struct bio *bi);
575 extern void md_write_end(struct mddev *mddev);
576 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
577 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
578 extern void md_finish_reshape(struct mddev *mddev);
580 extern int mddev_congested(struct mddev *mddev, int bits);
581 extern void md_flush_request(struct mddev *mddev, struct bio *bio);
582 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
583 sector_t sector, int size, struct page *page);
584 extern void md_super_wait(struct mddev *mddev);
585 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
586 struct page *page, int rw, bool metadata_op);
587 extern void md_do_sync(struct md_thread *thread);
588 extern void md_new_event(struct mddev *mddev);
589 extern int md_allow_write(struct mddev *mddev);
590 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
591 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
592 extern int md_check_no_bitmap(struct mddev *mddev);
593 extern int md_integrity_register(struct mddev *mddev);
594 extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
595 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
596 extern void restore_bitmap_write_access(struct file *file);
598 extern void mddev_init(struct mddev *mddev);
599 extern int md_run(struct mddev *mddev);
600 extern void md_stop(struct mddev *mddev);
601 extern void md_stop_writes(struct mddev *mddev);
602 extern int md_rdev_init(struct md_rdev *rdev);
603 extern void md_rdev_clear(struct md_rdev *rdev);
605 extern void mddev_suspend(struct mddev *mddev);
606 extern void mddev_resume(struct mddev *mddev);
607 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
608 struct mddev *mddev);
609 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
610 struct mddev *mddev);
611 extern void md_trim_bio(struct bio *bio, int offset, int size);
613 extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
614 static inline int mddev_check_plugged(struct mddev *mddev)
616 return !!blk_check_plugged(md_unplug, mddev,
617 sizeof(struct blk_plug_cb));
619 #endif /* _MD_MD_H */