xref: /linux/drivers/md/md.h (revision f83d9396d1f63048c423efa00e4e244da10a35fd)
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3    md.h : kernel internal structure of the Linux MD driver
4           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
5 
6 */
7 
8 #ifndef _MD_MD_H
9 #define _MD_MD_H
10 
11 #include <linux/blkdev.h>
12 #include <linux/backing-dev.h>
13 #include <linux/badblocks.h>
14 #include <linux/kobject.h>
15 #include <linux/list.h>
16 #include <linux/mm.h>
17 #include <linux/mutex.h>
18 #include <linux/timer.h>
19 #include <linux/wait.h>
20 #include <linux/workqueue.h>
21 #include "md-cluster.h"
22 
23 #define MaxSector (~(sector_t)0)
24 
25 /*
26  * These flags should really be called "NO_RETRY" rather than
27  * "FAILFAST" because they don't make any promise about time lapse,
28  * only about the number of retries, which will be zero.
29  * REQ_FAILFAST_DRIVER is not included because
30  * Commit: 4a27446f3e39 ("[SCSI] modify scsi to handle new fail fast flags.")
31  * seems to suggest that the errors it avoids retrying should usually
32  * be retried.
33  */
34 #define	MD_FAILFAST	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)
35 
36 /*
37  * The struct embedded in rdev is used to serialize IO.
38  */
39 struct serial_in_rdev {
40 	struct rb_root_cached serial_rb;
41 	spinlock_t serial_lock;
42 	wait_queue_head_t serial_io_wait;
43 };
44 
45 /*
46  * MD's 'extended' device
47  */
48 struct md_rdev {
49 	struct list_head same_set;	/* RAID devices within the same set */
50 
51 	sector_t sectors;		/* Device size (in 512bytes sectors) */
52 	struct mddev *mddev;		/* RAID array if running */
53 	int last_events;		/* IO event timestamp */
54 
55 	/*
56 	 * If meta_bdev is non-NULL, it means that a separate device is
57 	 * being used to store the metadata (superblock/bitmap) which
58 	 * would otherwise be contained on the same device as the data (bdev).
59 	 */
60 	struct block_device *meta_bdev;
61 	struct block_device *bdev;	/* block device handle */
62 
63 	struct page	*sb_page, *bb_page;
64 	int		sb_loaded;
65 	__u64		sb_events;
66 	sector_t	data_offset;	/* start of data in array */
67 	sector_t	new_data_offset;/* only relevant while reshaping */
68 	sector_t	sb_start;	/* offset of the super block (in 512byte sectors) */
69 	int		sb_size;	/* bytes in the superblock */
70 	int		preferred_minor;	/* autorun support */
71 
72 	struct kobject	kobj;
73 
74 	/* A device can be in one of three states based on two flags:
75 	 * Not working:   faulty==1 in_sync==0
76 	 * Fully working: faulty==0 in_sync==1
77 	 * Working, but not
78 	 * in sync with array
79 	 *                faulty==0 in_sync==0
80 	 *
81 	 * It can never have faulty==1, in_sync==1
82 	 * This reduces the burden of testing multiple flags in many cases
83 	 */
84 
85 	unsigned long	flags;	/* bit set of 'enum flag_bits' bits. */
86 	wait_queue_head_t blocked_wait;
87 
88 	int desc_nr;			/* descriptor index in the superblock */
89 	int raid_disk;			/* role of device in array */
90 	int new_raid_disk;		/* role that the device will have in
91 					 * the array after a level-change completes.
92 					 */
93 	int saved_raid_disk;		/* role that device used to have in the
94 					 * array and could again if we did a partial
95 					 * resync from the bitmap
96 					 */
97 	union {
98 		sector_t recovery_offset;/* If this device has been partially
99 					 * recovered, this is where we were
100 					 * up to.
101 					 */
102 		sector_t journal_tail;	/* If this device is a journal device,
103 					 * this is the journal tail (journal
104 					 * recovery start point)
105 					 */
106 	};
107 
108 	atomic_t	nr_pending;	/* number of pending requests.
109 					 * only maintained for arrays that
110 					 * support hot removal
111 					 */
112 	atomic_t	read_errors;	/* number of consecutive read errors that
113 					 * we have tried to ignore.
114 					 */
115 	time64_t	last_read_error;	/* monotonic time since our
116 						 * last read error
117 						 */
118 	atomic_t	corrected_errors; /* number of corrected read errors,
119 					   * for reporting to userspace and storing
120 					   * in superblock.
121 					   */
122 
123 	struct serial_in_rdev *serial;  /* used for raid1 io serialization */
124 
125 	struct work_struct del_work;	/* used for delayed sysfs removal */
126 
127 	struct kernfs_node *sysfs_state; /* handle for 'state'
128 					   * sysfs entry */
129 	/* handle for 'unacknowledged_bad_blocks' sysfs dentry */
130 	struct kernfs_node *sysfs_unack_badblocks;
131 	/* handle for 'bad_blocks' sysfs dentry */
132 	struct kernfs_node *sysfs_badblocks;
133 	struct badblocks badblocks;
134 
135 	struct {
136 		short offset;	/* Offset from superblock to start of PPL.
137 				 * Not used by external metadata. */
138 		unsigned int size;	/* Size in sectors of the PPL space */
139 		sector_t sector;	/* First sector of the PPL space */
140 	} ppl;
141 };
142 enum flag_bits {
143 	Faulty,			/* device is known to have a fault */
144 	In_sync,		/* device is in_sync with rest of array */
145 	Bitmap_sync,		/* ..actually, not quite In_sync.  Need a
146 				 * bitmap-based recovery to get fully in sync.
147 				 * The bit is only meaningful before device
148 				 * has been passed to pers->hot_add_disk.
149 				 */
150 	WriteMostly,		/* Avoid reading if at all possible */
151 	AutoDetected,		/* added by auto-detect */
152 	Blocked,		/* An error occurred but has not yet
153 				 * been acknowledged by the metadata
154 				 * handler, so don't allow writes
155 				 * until it is cleared */
156 	WriteErrorSeen,		/* A write error has been seen on this
157 				 * device
158 				 */
159 	FaultRecorded,		/* Intermediate state for clearing
160 				 * Blocked.  The Fault is/will-be
161 				 * recorded in the metadata, but that
162 				 * metadata hasn't been stored safely
163 				 * on disk yet.
164 				 */
165 	BlockedBadBlocks,	/* A writer is blocked because they
166 				 * found an unacknowledged bad-block.
167 				 * This can safely be cleared at any
168 				 * time, and the writer will re-check.
169 				 * It may be set at any time, and at
170 				 * worst the writer will timeout and
171 				 * re-check.  So setting it as
172 				 * accurately as possible is good, but
173 				 * not absolutely critical.
174 				 */
175 	WantReplacement,	/* This device is a candidate to be
176 				 * hot-replaced, either because it has
177 				 * reported some faults, or because
178 				 * of explicit request.
179 				 */
180 	Replacement,		/* This device is a replacement for
181 				 * a want_replacement device with same
182 				 * raid_disk number.
183 				 */
184 	Candidate,		/* For clustered environments only:
185 				 * This device is seen locally but not
186 				 * by the whole cluster
187 				 */
188 	Journal,		/* This device is used as journal for
189 				 * raid-5/6.
190 				 * Usually, this device should be faster
191 				 * than other devices in the array
192 				 */
193 	ClusterRemove,
194 	RemoveSynchronized,	/* synchronize_rcu() was called after
195 				 * this device was known to be faulty,
196 				 * so it is safe to remove without
197 				 * another synchronize_rcu() call.
198 				 */
199 	ExternalBbl,            /* External metadata provides bad
200 				 * block management for a disk
201 				 */
202 	FailFast,		/* Minimal retries should be attempted on
203 				 * this device, so use REQ_FAILFAST_DEV.
204 				 * Also don't try to repair failed reads.
205 				 * It is expects that no bad block log
206 				 * is present.
207 				 */
208 	LastDev,		/* Seems to be the last working dev as
209 				 * it didn't fail, so don't use FailFast
210 				 * any more for metadata
211 				 */
212 	CollisionCheck,		/*
213 				 * check if there is collision between raid1
214 				 * serial bios.
215 				 */
216 };
217 
218 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
219 			      sector_t *first_bad, int *bad_sectors)
220 {
221 	if (unlikely(rdev->badblocks.count)) {
222 		int rv = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
223 					sectors,
224 					first_bad, bad_sectors);
225 		if (rv)
226 			*first_bad -= rdev->data_offset;
227 		return rv;
228 	}
229 	return 0;
230 }
231 extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
232 			      int is_new);
233 extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
234 				int is_new);
235 struct md_cluster_info;
236 
237 /**
238  * enum mddev_flags - md device flags.
239  * @MD_ARRAY_FIRST_USE: First use of array, needs initialization.
240  * @MD_CLOSING: If set, we are closing the array, do not open it then.
241  * @MD_JOURNAL_CLEAN: A raid with journal is already clean.
242  * @MD_HAS_JOURNAL: The raid array has journal feature set.
243  * @MD_CLUSTER_RESYNC_LOCKED: cluster raid only, which means node, already took
244  *			       resync lock, need to release the lock.
245  * @MD_FAILFAST_SUPPORTED: Using MD_FAILFAST on metadata writes is supported as
246  *			    calls to md_error() will never cause the array to
247  *			    become failed.
248  * @MD_HAS_PPL:  The raid array has PPL feature set.
249  * @MD_HAS_MULTIPLE_PPLS: The raid array has multiple PPLs feature set.
250  * @MD_ALLOW_SB_UPDATE: md_check_recovery is allowed to update the metadata
251  *			 without taking reconfig_mutex.
252  * @MD_UPDATING_SB: md_check_recovery is updating the metadata without
253  *		     explicitly holding reconfig_mutex.
254  * @MD_NOT_READY: do_md_run() is active, so 'array_state', ust not report that
255  *		   array is ready yet.
256  * @MD_BROKEN: This is used to stop writes and mark array as failed.
257  *
258  * change UNSUPPORTED_MDDEV_FLAGS for each array type if new flag is added
259  */
260 enum mddev_flags {
261 	MD_ARRAY_FIRST_USE,
262 	MD_CLOSING,
263 	MD_JOURNAL_CLEAN,
264 	MD_HAS_JOURNAL,
265 	MD_CLUSTER_RESYNC_LOCKED,
266 	MD_FAILFAST_SUPPORTED,
267 	MD_HAS_PPL,
268 	MD_HAS_MULTIPLE_PPLS,
269 	MD_ALLOW_SB_UPDATE,
270 	MD_UPDATING_SB,
271 	MD_NOT_READY,
272 	MD_BROKEN,
273 };
274 
275 enum mddev_sb_flags {
276 	MD_SB_CHANGE_DEVS,		/* Some device status has changed */
277 	MD_SB_CHANGE_CLEAN,	/* transition to or from 'clean' */
278 	MD_SB_CHANGE_PENDING,	/* switch from 'clean' to 'active' in progress */
279 	MD_SB_NEED_REWRITE,	/* metadata write needs to be repeated */
280 };
281 
282 #define NR_SERIAL_INFOS		8
283 /* record current range of serialize IOs */
284 struct serial_info {
285 	struct rb_node node;
286 	sector_t start;		/* start sector of rb node */
287 	sector_t last;		/* end sector of rb node */
288 	sector_t _subtree_last; /* highest sector in subtree of rb node */
289 };
290 
291 struct mddev {
292 	void				*private;
293 	struct md_personality		*pers;
294 	dev_t				unit;
295 	int				md_minor;
296 	struct list_head		disks;
297 	unsigned long			flags;
298 	unsigned long			sb_flags;
299 
300 	int				suspended;
301 	atomic_t			active_io;
302 	int				ro;
303 	int				sysfs_active; /* set when sysfs deletes
304 						       * are happening, so run/
305 						       * takeover/stop are not safe
306 						       */
307 	struct gendisk			*gendisk;
308 
309 	struct kobject			kobj;
310 	int				hold_active;
311 #define	UNTIL_IOCTL	1
312 #define	UNTIL_STOP	2
313 
314 	/* Superblock information */
315 	int				major_version,
316 					minor_version,
317 					patch_version;
318 	int				persistent;
319 	int				external;	/* metadata is
320 							 * managed externally */
321 	char				metadata_type[17]; /* externally set*/
322 	int				chunk_sectors;
323 	time64_t			ctime, utime;
324 	int				level, layout;
325 	char				clevel[16];
326 	int				raid_disks;
327 	int				max_disks;
328 	sector_t			dev_sectors;	/* used size of
329 							 * component devices */
330 	sector_t			array_sectors; /* exported array size */
331 	int				external_size; /* size managed
332 							* externally */
333 	__u64				events;
334 	/* If the last 'event' was simply a clean->dirty transition, and
335 	 * we didn't write it to the spares, then it is safe and simple
336 	 * to just decrement the event count on a dirty->clean transition.
337 	 * So we record that possibility here.
338 	 */
339 	int				can_decrease_events;
340 
341 	char				uuid[16];
342 
343 	/* If the array is being reshaped, we need to record the
344 	 * new shape and an indication of where we are up to.
345 	 * This is written to the superblock.
346 	 * If reshape_position is MaxSector, then no reshape is happening (yet).
347 	 */
348 	sector_t			reshape_position;
349 	int				delta_disks, new_level, new_layout;
350 	int				new_chunk_sectors;
351 	int				reshape_backwards;
352 
353 	struct md_thread		*thread;	/* management thread */
354 	struct md_thread		*sync_thread;	/* doing resync or reconstruct */
355 
356 	/* 'last_sync_action' is initialized to "none".  It is set when a
357 	 * sync operation (i.e "data-check", "requested-resync", "resync",
358 	 * "recovery", or "reshape") is started.  It holds this value even
359 	 * when the sync thread is "frozen" (interrupted) or "idle" (stopped
360 	 * or finished).  It is overwritten when a new sync operation is begun.
361 	 */
362 	char				*last_sync_action;
363 	sector_t			curr_resync;	/* last block scheduled */
364 	/* As resync requests can complete out of order, we cannot easily track
365 	 * how much resync has been completed.  So we occasionally pause until
366 	 * everything completes, then set curr_resync_completed to curr_resync.
367 	 * As such it may be well behind the real resync mark, but it is a value
368 	 * we are certain of.
369 	 */
370 	sector_t			curr_resync_completed;
371 	unsigned long			resync_mark;	/* a recent timestamp */
372 	sector_t			resync_mark_cnt;/* blocks written at resync_mark */
373 	sector_t			curr_mark_cnt; /* blocks scheduled now */
374 
375 	sector_t			resync_max_sectors; /* may be set by personality */
376 
377 	atomic64_t			resync_mismatches; /* count of sectors where
378 							    * parity/replica mismatch found
379 							    */
380 
381 	/* allow user-space to request suspension of IO to regions of the array */
382 	sector_t			suspend_lo;
383 	sector_t			suspend_hi;
384 	/* if zero, use the system-wide default */
385 	int				sync_speed_min;
386 	int				sync_speed_max;
387 
388 	/* resync even though the same disks are shared among md-devices */
389 	int				parallel_resync;
390 
391 	int				ok_start_degraded;
392 
393 	unsigned long			recovery;
394 	/* If a RAID personality determines that recovery (of a particular
395 	 * device) will fail due to a read error on the source device, it
396 	 * takes a copy of this number and does not attempt recovery again
397 	 * until this number changes.
398 	 */
399 	int				recovery_disabled;
400 
401 	int				in_sync;	/* know to not need resync */
402 	/* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
403 	 * that we are never stopping an array while it is open.
404 	 * 'reconfig_mutex' protects all other reconfiguration.
405 	 * These locks are separate due to conflicting interactions
406 	 * with disk->open_mutex.
407 	 * Lock ordering is:
408 	 *  reconfig_mutex -> disk->open_mutex
409 	 *  disk->open_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
410 	 */
411 	struct mutex			open_mutex;
412 	struct mutex			reconfig_mutex;
413 	atomic_t			active;		/* general refcount */
414 	atomic_t			openers;	/* number of active opens */
415 
416 	int				changed;	/* True if we might need to
417 							 * reread partition info */
418 	int				degraded;	/* whether md should consider
419 							 * adding a spare
420 							 */
421 
422 	atomic_t			recovery_active; /* blocks scheduled, but not written */
423 	wait_queue_head_t		recovery_wait;
424 	sector_t			recovery_cp;
425 	sector_t			resync_min;	/* user requested sync
426 							 * starts here */
427 	sector_t			resync_max;	/* resync should pause
428 							 * when it gets here */
429 
430 	struct kernfs_node		*sysfs_state;	/* handle for 'array_state'
431 							 * file in sysfs.
432 							 */
433 	struct kernfs_node		*sysfs_action;  /* handle for 'sync_action' */
434 	struct kernfs_node		*sysfs_completed;	/*handle for 'sync_completed' */
435 	struct kernfs_node		*sysfs_degraded;	/*handle for 'degraded' */
436 	struct kernfs_node		*sysfs_level;		/*handle for 'level' */
437 
438 	struct work_struct del_work;	/* used for delayed sysfs removal */
439 
440 	/* "lock" protects:
441 	 *   flush_bio transition from NULL to !NULL
442 	 *   rdev superblocks, events
443 	 *   clearing MD_CHANGE_*
444 	 *   in_sync - and related safemode and MD_CHANGE changes
445 	 *   pers (also protected by reconfig_mutex and pending IO).
446 	 *   clearing ->bitmap
447 	 *   clearing ->bitmap_info.file
448 	 *   changing ->resync_{min,max}
449 	 *   setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
450 	 */
451 	spinlock_t			lock;
452 	wait_queue_head_t		sb_wait;	/* for waiting on superblock updates */
453 	atomic_t			pending_writes;	/* number of active superblock writes */
454 
455 	unsigned int			safemode;	/* if set, update "clean" superblock
456 							 * when no writes pending.
457 							 */
458 	unsigned int			safemode_delay;
459 	struct timer_list		safemode_timer;
460 	struct percpu_ref		writes_pending;
461 	int				sync_checkers;	/* # of threads checking writes_pending */
462 	struct request_queue		*queue;	/* for plugging ... */
463 
464 	struct bitmap			*bitmap; /* the bitmap for the device */
465 	struct {
466 		struct file		*file; /* the bitmap file */
467 		loff_t			offset; /* offset from superblock of
468 						 * start of bitmap. May be
469 						 * negative, but not '0'
470 						 * For external metadata, offset
471 						 * from start of device.
472 						 */
473 		unsigned long		space; /* space available at this offset */
474 		loff_t			default_offset; /* this is the offset to use when
475 							 * hot-adding a bitmap.  It should
476 							 * eventually be settable by sysfs.
477 							 */
478 		unsigned long		default_space; /* space available at
479 							* default offset */
480 		struct mutex		mutex;
481 		unsigned long		chunksize;
482 		unsigned long		daemon_sleep; /* how many jiffies between updates? */
483 		unsigned long		max_write_behind; /* write-behind mode */
484 		int			external;
485 		int			nodes; /* Maximum number of nodes in the cluster */
486 		char                    cluster_name[64]; /* Name of the cluster */
487 	} bitmap_info;
488 
489 	atomic_t			max_corr_read_errors; /* max read retries */
490 	struct list_head		all_mddevs;
491 
492 	const struct attribute_group	*to_remove;
493 
494 	struct bio_set			bio_set;
495 	struct bio_set			sync_set; /* for sync operations like
496 						   * metadata and bitmap writes
497 						   */
498 	struct bio_set			io_acct_set; /* for raid0 and raid5 io accounting */
499 
500 	/* Generic flush handling.
501 	 * The last to finish preflush schedules a worker to submit
502 	 * the rest of the request (without the REQ_PREFLUSH flag).
503 	 */
504 	struct bio *flush_bio;
505 	atomic_t flush_pending;
506 	ktime_t start_flush, prev_flush_start; /* prev_flush_start is when the previous completed
507 						* flush was started.
508 						*/
509 	struct work_struct flush_work;
510 	struct work_struct event_work;	/* used by dm to report failure event */
511 	mempool_t *serial_info_pool;
512 	void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
513 	struct md_cluster_info		*cluster_info;
514 	unsigned int			good_device_nr;	/* good device num within cluster raid */
515 	unsigned int			noio_flag; /* for memalloc scope API */
516 
517 	bool	has_superblocks:1;
518 	bool	fail_last_dev:1;
519 	bool	serialize_policy:1;
520 };
521 
522 enum recovery_flags {
523 	/*
524 	 * If neither SYNC or RESHAPE are set, then it is a recovery.
525 	 */
526 	MD_RECOVERY_RUNNING,	/* a thread is running, or about to be started */
527 	MD_RECOVERY_SYNC,	/* actually doing a resync, not a recovery */
528 	MD_RECOVERY_RECOVER,	/* doing recovery, or need to try it. */
529 	MD_RECOVERY_INTR,	/* resync needs to be aborted for some reason */
530 	MD_RECOVERY_DONE,	/* thread is done and is waiting to be reaped */
531 	MD_RECOVERY_NEEDED,	/* we might need to start a resync/recover */
532 	MD_RECOVERY_REQUESTED,	/* user-space has requested a sync (used with SYNC) */
533 	MD_RECOVERY_CHECK,	/* user-space request for check-only, no repair */
534 	MD_RECOVERY_RESHAPE,	/* A reshape is happening */
535 	MD_RECOVERY_FROZEN,	/* User request to abort, and not restart, any action */
536 	MD_RECOVERY_ERROR,	/* sync-action interrupted because io-error */
537 	MD_RECOVERY_WAIT,	/* waiting for pers->start() to finish */
538 	MD_RESYNCING_REMOTE,	/* remote node is running resync thread */
539 };
540 
541 static inline int __must_check mddev_lock(struct mddev *mddev)
542 {
543 	return mutex_lock_interruptible(&mddev->reconfig_mutex);
544 }
545 
546 /* Sometimes we need to take the lock in a situation where
547  * failure due to interrupts is not acceptable.
548  */
549 static inline void mddev_lock_nointr(struct mddev *mddev)
550 {
551 	mutex_lock(&mddev->reconfig_mutex);
552 }
553 
554 static inline int mddev_trylock(struct mddev *mddev)
555 {
556 	return mutex_trylock(&mddev->reconfig_mutex);
557 }
558 extern void mddev_unlock(struct mddev *mddev);
559 
560 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
561 {
562 	atomic_add(nr_sectors, &bdev->bd_disk->sync_io);
563 }
564 
565 static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
566 {
567 	md_sync_acct(bio->bi_bdev, nr_sectors);
568 }
569 
570 struct md_personality
571 {
572 	char *name;
573 	int level;
574 	struct list_head list;
575 	struct module *owner;
576 	bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);
577 	/*
578 	 * start up works that do NOT require md_thread. tasks that
579 	 * requires md_thread should go into start()
580 	 */
581 	int (*run)(struct mddev *mddev);
582 	/* start up works that require md threads */
583 	int (*start)(struct mddev *mddev);
584 	void (*free)(struct mddev *mddev, void *priv);
585 	void (*status)(struct seq_file *seq, struct mddev *mddev);
586 	/* error_handler must set ->faulty and clear ->in_sync
587 	 * if appropriate, and should abort recovery if needed
588 	 */
589 	void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
590 	int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
591 	int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
592 	int (*spare_active) (struct mddev *mddev);
593 	sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
594 	int (*resize) (struct mddev *mddev, sector_t sectors);
595 	sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
596 	int (*check_reshape) (struct mddev *mddev);
597 	int (*start_reshape) (struct mddev *mddev);
598 	void (*finish_reshape) (struct mddev *mddev);
599 	void (*update_reshape_pos) (struct mddev *mddev);
600 	/* quiesce suspends or resumes internal processing.
601 	 * 1 - stop new actions and wait for action io to complete
602 	 * 0 - return to normal behaviour
603 	 */
604 	void (*quiesce) (struct mddev *mddev, int quiesce);
605 	/* takeover is used to transition an array from one
606 	 * personality to another.  The new personality must be able
607 	 * to handle the data in the current layout.
608 	 * e.g. 2drive raid1 -> 2drive raid5
609 	 *      ndrive raid5 -> degraded n+1drive raid6 with special layout
610 	 * If the takeover succeeds, a new 'private' structure is returned.
611 	 * This needs to be installed and then ->run used to activate the
612 	 * array.
613 	 */
614 	void *(*takeover) (struct mddev *mddev);
615 	/* Changes the consistency policy of an active array. */
616 	int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
617 };
618 
619 struct md_sysfs_entry {
620 	struct attribute attr;
621 	ssize_t (*show)(struct mddev *, char *);
622 	ssize_t (*store)(struct mddev *, const char *, size_t);
623 };
624 extern const struct attribute_group md_bitmap_group;
625 
626 static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
627 {
628 	if (sd)
629 		return sysfs_get_dirent(sd, name);
630 	return sd;
631 }
632 static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
633 {
634 	if (sd)
635 		sysfs_notify_dirent(sd);
636 }
637 
638 static inline char * mdname (struct mddev * mddev)
639 {
640 	return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
641 }
642 
643 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
644 {
645 	char nm[20];
646 	if (!test_bit(Replacement, &rdev->flags) &&
647 	    !test_bit(Journal, &rdev->flags) &&
648 	    mddev->kobj.sd) {
649 		sprintf(nm, "rd%d", rdev->raid_disk);
650 		return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
651 	} else
652 		return 0;
653 }
654 
655 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
656 {
657 	char nm[20];
658 	if (!test_bit(Replacement, &rdev->flags) &&
659 	    !test_bit(Journal, &rdev->flags) &&
660 	    mddev->kobj.sd) {
661 		sprintf(nm, "rd%d", rdev->raid_disk);
662 		sysfs_remove_link(&mddev->kobj, nm);
663 	}
664 }
665 
666 /*
667  * iterates through some rdev ringlist. It's safe to remove the
668  * current 'rdev'. Dont touch 'tmp' though.
669  */
670 #define rdev_for_each_list(rdev, tmp, head)				\
671 	list_for_each_entry_safe(rdev, tmp, head, same_set)
672 
673 /*
674  * iterates through the 'same array disks' ringlist
675  */
676 #define rdev_for_each(rdev, mddev)				\
677 	list_for_each_entry(rdev, &((mddev)->disks), same_set)
678 
679 #define rdev_for_each_safe(rdev, tmp, mddev)				\
680 	list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
681 
682 #define rdev_for_each_rcu(rdev, mddev)				\
683 	list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
684 
685 struct md_thread {
686 	void			(*run) (struct md_thread *thread);
687 	struct mddev		*mddev;
688 	wait_queue_head_t	wqueue;
689 	unsigned long		flags;
690 	struct task_struct	*tsk;
691 	unsigned long		timeout;
692 	void			*private;
693 };
694 
695 struct md_io_acct {
696 	struct bio *orig_bio;
697 	unsigned long start_time;
698 	struct bio bio_clone;
699 };
700 
701 #define THREAD_WAKEUP  0
702 
703 static inline void safe_put_page(struct page *p)
704 {
705 	if (p) put_page(p);
706 }
707 
708 extern int register_md_personality(struct md_personality *p);
709 extern int unregister_md_personality(struct md_personality *p);
710 extern int register_md_cluster_operations(struct md_cluster_operations *ops,
711 		struct module *module);
712 extern int unregister_md_cluster_operations(void);
713 extern int md_setup_cluster(struct mddev *mddev, int nodes);
714 extern void md_cluster_stop(struct mddev *mddev);
715 extern struct md_thread *md_register_thread(
716 	void (*run)(struct md_thread *thread),
717 	struct mddev *mddev,
718 	const char *name);
719 extern void md_unregister_thread(struct md_thread **threadp);
720 extern void md_wakeup_thread(struct md_thread *thread);
721 extern void md_check_recovery(struct mddev *mddev);
722 extern void md_reap_sync_thread(struct mddev *mddev);
723 extern int mddev_init_writes_pending(struct mddev *mddev);
724 extern bool md_write_start(struct mddev *mddev, struct bio *bi);
725 extern void md_write_inc(struct mddev *mddev, struct bio *bi);
726 extern void md_write_end(struct mddev *mddev);
727 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
728 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
729 extern void md_finish_reshape(struct mddev *mddev);
730 void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
731 			struct bio *bio, sector_t start, sector_t size);
732 int acct_bioset_init(struct mddev *mddev);
733 void acct_bioset_exit(struct mddev *mddev);
734 void md_account_bio(struct mddev *mddev, struct bio **bio);
735 
736 extern bool __must_check md_flush_request(struct mddev *mddev, struct bio *bio);
737 extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
738 			   sector_t sector, int size, struct page *page);
739 extern int md_super_wait(struct mddev *mddev);
740 extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
741 			struct page *page, int op, int op_flags,
742 			bool metadata_op);
743 extern void md_do_sync(struct md_thread *thread);
744 extern void md_new_event(void);
745 extern void md_allow_write(struct mddev *mddev);
746 extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
747 extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
748 extern int md_check_no_bitmap(struct mddev *mddev);
749 extern int md_integrity_register(struct mddev *mddev);
750 extern int md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
751 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
752 
753 extern void mddev_init(struct mddev *mddev);
754 extern int md_run(struct mddev *mddev);
755 extern int md_start(struct mddev *mddev);
756 extern void md_stop(struct mddev *mddev);
757 extern void md_stop_writes(struct mddev *mddev);
758 extern int md_rdev_init(struct md_rdev *rdev);
759 extern void md_rdev_clear(struct md_rdev *rdev);
760 
761 extern void md_handle_request(struct mddev *mddev, struct bio *bio);
762 extern void mddev_suspend(struct mddev *mddev);
763 extern void mddev_resume(struct mddev *mddev);
764 
765 extern void md_reload_sb(struct mddev *mddev, int raid_disk);
766 extern void md_update_sb(struct mddev *mddev, int force);
767 extern void md_kick_rdev_from_array(struct md_rdev * rdev);
768 extern void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
769 				     bool is_suspend);
770 extern void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
771 				      bool is_suspend);
772 struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
773 struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev);
774 
775 static inline bool is_mddev_broken(struct md_rdev *rdev, const char *md_type)
776 {
777 	if (!disk_live(rdev->bdev->bd_disk)) {
778 		if (!test_and_set_bit(MD_BROKEN, &rdev->mddev->flags))
779 			pr_warn("md: %s: %s array has a missing/failed member\n",
780 				mdname(rdev->mddev), md_type);
781 		return true;
782 	}
783 	return false;
784 }
785 
786 static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
787 {
788 	int faulty = test_bit(Faulty, &rdev->flags);
789 	if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
790 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
791 		md_wakeup_thread(mddev->thread);
792 	}
793 }
794 
795 extern struct md_cluster_operations *md_cluster_ops;
796 static inline int mddev_is_clustered(struct mddev *mddev)
797 {
798 	return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
799 }
800 
801 /* clear unsupported mddev_flags */
802 static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
803 	unsigned long unsupported_flags)
804 {
805 	mddev->flags &= ~unsupported_flags;
806 }
807 
808 static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
809 {
810 	if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
811 	    !bio->bi_bdev->bd_disk->queue->limits.max_write_zeroes_sectors)
812 		mddev->queue->limits.max_write_zeroes_sectors = 0;
813 }
814 
815 struct mdu_array_info_s;
816 struct mdu_disk_info_s;
817 
818 extern int mdp_major;
819 void md_autostart_arrays(int part);
820 int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info);
821 int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info);
822 int do_md_run(struct mddev *mddev);
823 
824 extern const struct block_device_operations md_fops;
825 
826 #endif /* _MD_MD_H */
827