Root/drivers/md/md.h

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

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