xref: /linux/drivers/md/md.h (revision cc04a46f11ea046ed53e2c832ae29e4790f7e35f)
1 /*
2    md.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/backing-dev.h>
20 #include <linux/kobject.h>
21 #include <linux/list.h>
22 #include <linux/mm.h>
23 #include <linux/mutex.h>
24 #include <linux/timer.h>
25 #include <linux/wait.h>
26 #include <linux/workqueue.h>
27 #include "md-cluster.h"
28 
29 #define MaxSector (~(sector_t)0)
30 
31 /* Bad block numbers are stored sorted in a single page.
32  * 64bits is used for each block or extent.
33  * 54 bits are sector number, 9 bits are extent size,
34  * 1 bit is an 'acknowledged' flag.
35  */
36 #define MD_MAX_BADBLOCKS	(PAGE_SIZE/8)
37 
38 /*
39  * MD's 'extended' device
40  */
41 struct md_rdev {
42 	struct list_head same_set;	/* RAID devices within the same set */
43 
44 	sector_t sectors;		/* Device size (in 512bytes sectors) */
45 	struct mddev *mddev;		/* RAID array if running */
46 	int last_events;		/* IO event timestamp */
47 
48 	/*
49 	 * If meta_bdev is non-NULL, it means that a separate device is
50 	 * being used to store the metadata (superblock/bitmap) which
51 	 * would otherwise be contained on the same device as the data (bdev).
52 	 */
53 	struct block_device *meta_bdev;
54 	struct block_device *bdev;	/* block device handle */
55 
56 	struct page	*sb_page, *bb_page;
57 	int		sb_loaded;
58 	__u64		sb_events;
59 	sector_t	data_offset;	/* start of data in array */
60 	sector_t	new_data_offset;/* only relevant while reshaping */
61 	sector_t	sb_start;	/* offset of the super block (in 512byte sectors) */
62 	int		sb_size;	/* bytes in the superblock */
63 	int		preferred_minor;	/* autorun support */
64 
65 	struct kobject	kobj;
66 
67 	/* A device can be in one of three states based on two flags:
68 	 * Not working:   faulty==1 in_sync==0
69 	 * Fully working: faulty==0 in_sync==1
70 	 * Working, but not
71 	 * in sync with array
72 	 *                faulty==0 in_sync==0
73 	 *
74 	 * It can never have faulty==1, in_sync==1
75 	 * This reduces the burden of testing multiple flags in many cases
76 	 */
77 
78 	unsigned long	flags;	/* bit set of 'enum flag_bits' bits. */
79 	wait_queue_head_t blocked_wait;
80 
81 	int desc_nr;			/* descriptor index in the superblock */
82 	int raid_disk;			/* role of device in array */
83 	int new_raid_disk;		/* role that the device will have in
84 					 * the array after a level-change completes.
85 					 */
86 	int saved_raid_disk;		/* role that device used to have in the
87 					 * array and could again if we did a partial
88 					 * resync from the bitmap
89 					 */
90 	sector_t	recovery_offset;/* If this device has been partially
91 					 * recovered, this is where we were
92 					 * up to.
93 					 */
94 
95 	atomic_t	nr_pending;	/* number of pending requests.
96 					 * only maintained for arrays that
97 					 * support hot removal
98 					 */
99 	atomic_t	read_errors;	/* number of consecutive read errors that
100 					 * we have tried to ignore.
101 					 */
102 	struct timespec last_read_error;	/* monotonic time since our
103 						 * last read error
104 						 */
105 	atomic_t	corrected_errors; /* number of corrected read errors,
106 					   * for reporting to userspace and storing
107 					   * in superblock.
108 					   */
109 	struct work_struct del_work;	/* used for delayed sysfs removal */
110 
111 	struct kernfs_node *sysfs_state; /* handle for 'state'
112 					   * sysfs entry */
113 
114 	struct badblocks {
115 		int	count;		/* count of bad blocks */
116 		int	unacked_exist;	/* there probably are unacknowledged
117 					 * bad blocks.  This is only cleared
118 					 * when a read discovers none
119 					 */
120 		int	shift;		/* shift from sectors to block size
121 					 * a -ve shift means badblocks are
122 					 * disabled.*/
123 		u64	*page;		/* badblock list */
124 		int	changed;
125 		seqlock_t lock;
126 
127 		sector_t sector;
128 		sector_t size;		/* in sectors */
129 	} badblocks;
130 };
131 enum flag_bits {
132 	Faulty,			/* device is known to have a fault */
133 	In_sync,		/* device is in_sync with rest of array */
134 	Bitmap_sync,		/* ..actually, not quite In_sync.  Need a
135 				 * bitmap-based recovery to get fully in sync
136 				 */
137 	WriteMostly,		/* Avoid reading if at all possible */
138 	AutoDetected,		/* added by auto-detect */
139 	Blocked,		/* An error occurred but has not yet
140 				 * been acknowledged by the metadata
141 				 * handler, so don't allow writes
142 				 * until it is cleared */
143 	WriteErrorSeen,		/* A write error has been seen on this
144 				 * device
145 				 */
146 	FaultRecorded,		/* Intermediate state for clearing
147 				 * Blocked.  The Fault is/will-be
148 				 * recorded in the metadata, but that
149 				 * metadata hasn't been stored safely
150 				 * on disk yet.
151 				 */
152 	BlockedBadBlocks,	/* A writer is blocked because they
153 				 * found an unacknowledged bad-block.
154 				 * This can safely be cleared at any
155 				 * time, and the writer will re-check.
156 				 * It may be set at any time, and at
157 				 * worst the writer will timeout and
158 				 * re-check.  So setting it as
159 				 * accurately as possible is good, but
160 				 * not absolutely critical.
161 				 */
162 	WantReplacement,	/* This device is a candidate to be
163 				 * hot-replaced, either because it has
164 				 * reported some faults, or because
165 				 * of explicit request.
166 				 */
167 	Replacement,		/* This device is a replacement for
168 				 * a want_replacement device with same
169 				 * raid_disk number.
170 				 */
171 	Candidate,		/* For clustered environments only:
172 				 * This device is seen locally but not
173 				 * by the whole cluster
174 				 */
175 };
176 
177 #define BB_LEN_MASK	(0x00000000000001FFULL)
178 #define BB_OFFSET_MASK	(0x7FFFFFFFFFFFFE00ULL)
179 #define BB_ACK_MASK	(0x8000000000000000ULL)
180 #define BB_MAX_LEN	512
181 #define BB_OFFSET(x)	(((x) & BB_OFFSET_MASK) >> 9)
182 #define BB_LEN(x)	(((x) & BB_LEN_MASK) + 1)
183 #define BB_ACK(x)	(!!((x) & BB_ACK_MASK))
184 #define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
185 
186 extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
187 			  sector_t *first_bad, int *bad_sectors);
188 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
189 			      sector_t *first_bad, int *bad_sectors)
190 {
191 	if (unlikely(rdev->badblocks.count)) {
192 		int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
193 					sectors,
194 					first_bad, bad_sectors);
195 		if (rv)
196 			*first_bad -= rdev->data_offset;
197 		return rv;
198 	}
199 	return 0;
200 }
201 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
202 			      int is_new);
203 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
204 				int is_new);
205 extern void md_ack_all_badblocks(struct badblocks *bb);
206 
207 struct md_cluster_info;
208 
209 struct mddev {
210 	void				*private;
211 	struct md_personality		*pers;
212 	dev_t				unit;
213 	int				md_minor;
214 	struct list_head		disks;
215 	unsigned long			flags;
216 #define MD_CHANGE_DEVS	0	/* Some device status has changed */
217 #define MD_CHANGE_CLEAN 1	/* transition to or from 'clean' */
218 #define MD_CHANGE_PENDING 2	/* switch from 'clean' to 'active' in progress */
219 #define MD_UPDATE_SB_FLAGS (1 | 2 | 4)	/* If these are set, md_update_sb needed */
220 #define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
221 #define MD_STILL_CLOSED	4	/* If set, then array has not been opened since
222 				 * md_ioctl checked on it.
223 				 */
224 
225 	int				suspended;
226 	atomic_t			active_io;
227 	int				ro;
228 	int				sysfs_active; /* set when sysfs deletes
229 						       * are happening, so run/
230 						       * takeover/stop are not safe
231 						       */
232 	int				ready; /* See when safe to pass
233 						* IO requests down */
234 	struct gendisk			*gendisk;
235 
236 	struct kobject			kobj;
237 	int				hold_active;
238 #define	UNTIL_IOCTL	1
239 #define	UNTIL_STOP	2
240 
241 	/* Superblock information */
242 	int				major_version,
243 					minor_version,
244 					patch_version;
245 	int				persistent;
246 	int				external;	/* metadata is
247 							 * managed externally */
248 	char				metadata_type[17]; /* externally set*/
249 	int				chunk_sectors;
250 	time_t				ctime, utime;
251 	int				level, layout;
252 	char				clevel[16];
253 	int				raid_disks;
254 	int				max_disks;
255 	sector_t			dev_sectors;	/* used size of
256 							 * component devices */
257 	sector_t			array_sectors; /* exported array size */
258 	int				external_size; /* size managed
259 							* externally */
260 	__u64				events;
261 	/* If the last 'event' was simply a clean->dirty transition, and
262 	 * we didn't write it to the spares, then it is safe and simple
263 	 * to just decrement the event count on a dirty->clean transition.
264 	 * So we record that possibility here.
265 	 */
266 	int				can_decrease_events;
267 
268 	char				uuid[16];
269 
270 	/* If the array is being reshaped, we need to record the
271 	 * new shape and an indication of where we are up to.
272 	 * This is written to the superblock.
273 	 * If reshape_position is MaxSector, then no reshape is happening (yet).
274 	 */
275 	sector_t			reshape_position;
276 	int				delta_disks, new_level, new_layout;
277 	int				new_chunk_sectors;
278 	int				reshape_backwards;
279 
280 	struct md_thread		*thread;	/* management thread */
281 	struct md_thread		*sync_thread;	/* doing resync or reconstruct */
282 
283 	/* 'last_sync_action' is initialized to "none".  It is set when a
284 	 * sync operation (i.e "data-check", "requested-resync", "resync",
285 	 * "recovery", or "reshape") is started.  It holds this value even
286 	 * when the sync thread is "frozen" (interrupted) or "idle" (stopped
287 	 * or finished).  It is overwritten when a new sync operation is begun.
288 	 */
289 	char				*last_sync_action;
290 	sector_t			curr_resync;	/* last block scheduled */
291 	/* As resync requests can complete out of order, we cannot easily track
292 	 * how much resync has been completed.  So we occasionally pause until
293 	 * everything completes, then set curr_resync_completed to curr_resync.
294 	 * As such it may be well behind the real resync mark, but it is a value
295 	 * we are certain of.
296 	 */
297 	sector_t			curr_resync_completed;
298 	unsigned long			resync_mark;	/* a recent timestamp */
299 	sector_t			resync_mark_cnt;/* blocks written at resync_mark */
300 	sector_t			curr_mark_cnt; /* blocks scheduled now */
301 
302 	sector_t			resync_max_sectors; /* may be set by personality */
303 
304 	atomic64_t			resync_mismatches; /* count of sectors where
305 							    * parity/replica mismatch found
306 							    */
307 
308 	/* allow user-space to request suspension of IO to regions of the array */
309 	sector_t			suspend_lo;
310 	sector_t			suspend_hi;
311 	/* if zero, use the system-wide default */
312 	int				sync_speed_min;
313 	int				sync_speed_max;
314 
315 	/* resync even though the same disks are shared among md-devices */
316 	int				parallel_resync;
317 
318 	int				ok_start_degraded;
319 	/* recovery/resync flags
320 	 * NEEDED:   we might need to start a resync/recover
321 	 * RUNNING:  a thread is running, or about to be started
322 	 * SYNC:     actually doing a resync, not a recovery
323 	 * RECOVER:  doing recovery, or need to try it.
324 	 * INTR:     resync needs to be aborted for some reason
325 	 * DONE:     thread is done and is waiting to be reaped
326 	 * REQUEST:  user-space has requested a sync (used with SYNC)
327 	 * CHECK:    user-space request for check-only, no repair
328 	 * RESHAPE:  A reshape is happening
329 	 * ERROR:    sync-action interrupted because io-error
330 	 *
331 	 * If neither SYNC or RESHAPE are set, then it is a recovery.
332 	 */
333 #define	MD_RECOVERY_RUNNING	0
334 #define	MD_RECOVERY_SYNC	1
335 #define	MD_RECOVERY_RECOVER	2
336 #define	MD_RECOVERY_INTR	3
337 #define	MD_RECOVERY_DONE	4
338 #define	MD_RECOVERY_NEEDED	5
339 #define	MD_RECOVERY_REQUESTED	6
340 #define	MD_RECOVERY_CHECK	7
341 #define MD_RECOVERY_RESHAPE	8
342 #define	MD_RECOVERY_FROZEN	9
343 #define	MD_RECOVERY_ERROR	10
344 
345 	unsigned long			recovery;
346 	/* If a RAID personality determines that recovery (of a particular
347 	 * device) will fail due to a read error on the source device, it
348 	 * takes a copy of this number and does not attempt recovery again
349 	 * until this number changes.
350 	 */
351 	int				recovery_disabled;
352 
353 	int				in_sync;	/* know to not need resync */
354 	/* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
355 	 * that we are never stopping an array while it is open.
356 	 * 'reconfig_mutex' protects all other reconfiguration.
357 	 * These locks are separate due to conflicting interactions
358 	 * with bdev->bd_mutex.
359 	 * Lock ordering is:
360 	 *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
361 	 *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
362 	 */
363 	struct mutex			open_mutex;
364 	struct mutex			reconfig_mutex;
365 	atomic_t			active;		/* general refcount */
366 	atomic_t			openers;	/* number of active opens */
367 
368 	int				changed;	/* True if we might need to
369 							 * reread partition info */
370 	int				degraded;	/* whether md should consider
371 							 * adding a spare
372 							 */
373 
374 	atomic_t			recovery_active; /* blocks scheduled, but not written */
375 	wait_queue_head_t		recovery_wait;
376 	sector_t			recovery_cp;
377 	sector_t			resync_min;	/* user requested sync
378 							 * starts here */
379 	sector_t			resync_max;	/* resync should pause
380 							 * when it gets here */
381 
382 	struct kernfs_node		*sysfs_state;	/* handle for 'array_state'
383 							 * file in sysfs.
384 							 */
385 	struct kernfs_node		*sysfs_action;  /* handle for 'sync_action' */
386 
387 	struct work_struct del_work;	/* used for delayed sysfs removal */
388 
389 	/* "lock" protects:
390 	 *   flush_bio transition from NULL to !NULL
391 	 *   rdev superblocks, events
392 	 *   clearing MD_CHANGE_*
393 	 *   in_sync - and related safemode and MD_CHANGE changes
394 	 *   pers (also protected by reconfig_mutex and pending IO).
395 	 *   clearing ->bitmap
396 	 *   clearing ->bitmap_info.file
397 	 *   changing ->resync_{min,max}
398 	 *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
399 	 */
400 	spinlock_t			lock;
401 	wait_queue_head_t		sb_wait;	/* for waiting on superblock updates */
402 	atomic_t			pending_writes;	/* number of active superblock writes */
403 
404 	unsigned int			safemode;	/* if set, update "clean" superblock
405 							 * when no writes pending.
406 							 */
407 	unsigned int			safemode_delay;
408 	struct timer_list		safemode_timer;
409 	atomic_t			writes_pending;
410 	struct request_queue		*queue;	/* for plugging ... */
411 
412 	struct bitmap			*bitmap; /* the bitmap for the device */
413 	struct {
414 		struct file		*file; /* the bitmap file */
415 		loff_t			offset; /* offset from superblock of
416 						 * start of bitmap. May be
417 						 * negative, but not '0'
418 						 * For external metadata, offset
419 						 * from start of device.
420 						 */
421 		unsigned long		space; /* space available at this offset */
422 		loff_t			default_offset; /* this is the offset to use when
423 							 * hot-adding a bitmap.  It should
424 							 * eventually be settable by sysfs.
425 							 */
426 		unsigned long		default_space; /* space available at
427 							* default offset */
428 		struct mutex		mutex;
429 		unsigned long		chunksize;
430 		unsigned long		daemon_sleep; /* how many jiffies between updates? */
431 		unsigned long		max_write_behind; /* write-behind mode */
432 		int			external;
433 		int			nodes; /* Maximum number of nodes in the cluster */
434 		char                    cluster_name[64]; /* Name of the cluster */
435 	} bitmap_info;
436 
437 	atomic_t			max_corr_read_errors; /* max read retries */
438 	struct list_head		all_mddevs;
439 
440 	struct attribute_group		*to_remove;
441 
442 	struct bio_set			*bio_set;
443 
444 	/* Generic flush handling.
445 	 * The last to finish preflush schedules a worker to submit
446 	 * the rest of the request (without the REQ_FLUSH flag).
447 	 */
448 	struct bio *flush_bio;
449 	atomic_t flush_pending;
450 	struct work_struct flush_work;
451 	struct work_struct event_work;	/* used by dm to report failure event */
452 	void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
453 	struct md_cluster_info		*cluster_info;
454 };
455 
456 static inline int __must_check mddev_lock(struct mddev *mddev)
457 {
458 	return mutex_lock_interruptible(&mddev->reconfig_mutex);
459 }
460 
461 /* Sometimes we need to take the lock in a situation where
462  * failure due to interrupts is not acceptable.
463  */
464 static inline void mddev_lock_nointr(struct mddev *mddev)
465 {
466 	mutex_lock(&mddev->reconfig_mutex);
467 }
468 
469 static inline int mddev_is_locked(struct mddev *mddev)
470 {
471 	return mutex_is_locked(&mddev->reconfig_mutex);
472 }
473 
474 static inline int mddev_trylock(struct mddev *mddev)
475 {
476 	return mutex_trylock(&mddev->reconfig_mutex);
477 }
478 extern void mddev_unlock(struct mddev *mddev);
479 
480 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
481 {
482 	atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
483 }
484 
485 struct md_personality
486 {
487 	char *name;
488 	int level;
489 	struct list_head list;
490 	struct module *owner;
491 	void (*make_request)(struct mddev *mddev, struct bio *bio);
492 	int (*run)(struct mddev *mddev);
493 	void (*free)(struct mddev *mddev, void *priv);
494 	void (*status)(struct seq_file *seq, struct mddev *mddev);
495 	/* error_handler must set ->faulty and clear ->in_sync
496 	 * if appropriate, and should abort recovery if needed
497 	 */
498 	void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
499 	int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
500 	int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
501 	int (*spare_active) (struct mddev *mddev);
502 	sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
503 	int (*resize) (struct mddev *mddev, sector_t sectors);
504 	sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
505 	int (*check_reshape) (struct mddev *mddev);
506 	int (*start_reshape) (struct mddev *mddev);
507 	void (*finish_reshape) (struct mddev *mddev);
508 	/* quiesce moves between quiescence states
509 	 * 0 - fully active
510 	 * 1 - no new requests allowed
511 	 * others - reserved
512 	 */
513 	void (*quiesce) (struct mddev *mddev, int state);
514 	/* takeover is used to transition an array from one
515 	 * personality to another.  The new personality must be able
516 	 * to handle the data in the current layout.
517 	 * e.g. 2drive raid1 -> 2drive raid5
518 	 *      ndrive raid5 -> degraded n+1drive raid6 with special layout
519 	 * If the takeover succeeds, a new 'private' structure is returned.
520 	 * This needs to be installed and then ->run used to activate the
521 	 * array.
522 	 */
523 	void *(*takeover) (struct mddev *mddev);
524 	/* congested implements bdi.congested_fn().
525 	 * Will not be called while array is 'suspended' */
526 	int (*congested)(struct mddev *mddev, int bits);
527 };
528 
529 struct md_sysfs_entry {
530 	struct attribute attr;
531 	ssize_t (*show)(struct mddev *, char *);
532 	ssize_t (*store)(struct mddev *, const char *, size_t);
533 };
534 extern struct attribute_group md_bitmap_group;
535 
536 static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
537 {
538 	if (sd)
539 		return sysfs_get_dirent(sd, name);
540 	return sd;
541 }
542 static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
543 {
544 	if (sd)
545 		sysfs_notify_dirent(sd);
546 }
547 
548 static inline char * mdname (struct mddev * mddev)
549 {
550 	return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
551 }
552 
553 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
554 {
555 	char nm[20];
556 	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
557 		sprintf(nm, "rd%d", rdev->raid_disk);
558 		return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
559 	} else
560 		return 0;
561 }
562 
563 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
564 {
565 	char nm[20];
566 	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
567 		sprintf(nm, "rd%d", rdev->raid_disk);
568 		sysfs_remove_link(&mddev->kobj, nm);
569 	}
570 }
571 
572 /*
573  * iterates through some rdev ringlist. It's safe to remove the
574  * current 'rdev'. Dont touch 'tmp' though.
575  */
576 #define rdev_for_each_list(rdev, tmp, head)				\
577 	list_for_each_entry_safe(rdev, tmp, head, same_set)
578 
579 /*
580  * iterates through the 'same array disks' ringlist
581  */
582 #define rdev_for_each(rdev, mddev)				\
583 	list_for_each_entry(rdev, &((mddev)->disks), same_set)
584 
585 #define rdev_for_each_safe(rdev, tmp, mddev)				\
586 	list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
587 
588 #define rdev_for_each_rcu(rdev, mddev)				\
589 	list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
590 
591 struct md_thread {
592 	void			(*run) (struct md_thread *thread);
593 	struct mddev		*mddev;
594 	wait_queue_head_t	wqueue;
595 	unsigned long		flags;
596 	struct task_struct	*tsk;
597 	unsigned long		timeout;
598 	void			*private;
599 };
600 
601 #define THREAD_WAKEUP  0
602 
603 static inline void safe_put_page(struct page *p)
604 {
605 	if (p) put_page(p);
606 }
607 
608 extern int register_md_personality(struct md_personality *p);
609 extern int unregister_md_personality(struct md_personality *p);
610 extern int register_md_cluster_operations(struct md_cluster_operations *ops,
611 		struct module *module);
612 extern int unregister_md_cluster_operations(void);
613 extern int md_setup_cluster(struct mddev *mddev, int nodes);
614 extern void md_cluster_stop(struct mddev *mddev);
615 extern struct md_thread *md_register_thread(
616 	void (*run)(struct md_thread *thread),
617 	struct mddev *mddev,
618 	const char *name);
619 extern void md_unregister_thread(struct md_thread **threadp);
620 extern void md_wakeup_thread(struct md_thread *thread);
621 extern void md_check_recovery(struct mddev *mddev);
622 extern void md_reap_sync_thread(struct mddev *mddev);
623 extern void md_write_start(struct mddev *mddev, struct bio *bi);
624 extern void md_write_end(struct mddev *mddev);
625 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
626 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
627 extern void md_finish_reshape(struct mddev *mddev);
628 
629 extern int mddev_congested(struct mddev *mddev, int bits);
630 extern void md_flush_request(struct mddev *mddev, struct bio *bio);
631 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
632 			   sector_t sector, int size, struct page *page);
633 extern void md_super_wait(struct mddev *mddev);
634 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
635 			struct page *page, int rw, bool metadata_op);
636 extern void md_do_sync(struct md_thread *thread);
637 extern void md_new_event(struct mddev *mddev);
638 extern int md_allow_write(struct mddev *mddev);
639 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
640 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
641 extern int md_check_no_bitmap(struct mddev *mddev);
642 extern int md_integrity_register(struct mddev *mddev);
643 extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
644 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
645 
646 extern void mddev_init(struct mddev *mddev);
647 extern int md_run(struct mddev *mddev);
648 extern void md_stop(struct mddev *mddev);
649 extern void md_stop_writes(struct mddev *mddev);
650 extern int md_rdev_init(struct md_rdev *rdev);
651 extern void md_rdev_clear(struct md_rdev *rdev);
652 
653 extern void mddev_suspend(struct mddev *mddev);
654 extern void mddev_resume(struct mddev *mddev);
655 extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
656 				   struct mddev *mddev);
657 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
658 				   struct mddev *mddev);
659 
660 extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
661 extern void md_reload_sb(struct mddev *mddev);
662 extern void md_update_sb(struct mddev *mddev, int force);
663 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
664 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
665 static inline int mddev_check_plugged(struct mddev *mddev)
666 {
667 	return !!blk_check_plugged(md_unplug, mddev,
668 				   sizeof(struct blk_plug_cb));
669 }
670 
671 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
672 {
673 	int faulty = test_bit(Faulty, &rdev->flags);
674 	if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
675 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
676 		md_wakeup_thread(mddev->thread);
677 	}
678 }
679 
680 extern struct md_cluster_operations *md_cluster_ops;
681 static inline int mddev_is_clustered(struct mddev *mddev)
682 {
683 	return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
684 }
685 #endif /* _MD_MD_H */
686