Merge branch 'for-linus' of git://neil.brown.name/md
[sfrench/cifs-2.6.git] / drivers / md / md.h
1 /*
2    md_k.h : kernel internal structure of the Linux MD driver
3           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
4           
5    This program is free software; you can redistribute it and/or modify
6    it under the terms of the GNU General Public License as published by
7    the Free Software Foundation; either version 2, or (at your option)
8    any later version.
9    
10    You should have received a copy of the GNU General Public License
11    (for example /usr/src/linux/COPYING); if not, write to the Free
12    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
13 */
14
15 #ifndef _MD_MD_H
16 #define _MD_MD_H
17
18 #include <linux/blkdev.h>
19 #include <linux/kobject.h>
20 #include <linux/list.h>
21 #include <linux/mm.h>
22 #include <linux/mutex.h>
23 #include <linux/timer.h>
24 #include <linux/wait.h>
25 #include <linux/workqueue.h>
26
27 #define MaxSector (~(sector_t)0)
28
29 typedef struct mddev_s mddev_t;
30 typedef struct mdk_rdev_s mdk_rdev_t;
31
32 /* generic plugging support - like that provided with request_queue,
33  * but does not require a request_queue
34  */
35 struct plug_handle {
36         void                    (*unplug_fn)(struct plug_handle *);
37         struct timer_list       unplug_timer;
38         struct work_struct      unplug_work;
39         unsigned long           unplug_flag;
40 };
41 #define PLUGGED_FLAG 1
42 void plugger_init(struct plug_handle *plug,
43                   void (*unplug_fn)(struct plug_handle *));
44 void plugger_set_plug(struct plug_handle *plug);
45 int plugger_remove_plug(struct plug_handle *plug);
46 static inline void plugger_flush(struct plug_handle *plug)
47 {
48         del_timer_sync(&plug->unplug_timer);
49         cancel_work_sync(&plug->unplug_work);
50 }
51
52 /*
53  * MD's 'extended' device
54  */
55 struct mdk_rdev_s
56 {
57         struct list_head same_set;      /* RAID devices within the same set */
58
59         sector_t sectors;               /* Device size (in 512bytes sectors) */
60         mddev_t *mddev;                 /* RAID array if running */
61         int last_events;                /* IO event timestamp */
62
63         struct block_device *bdev;      /* block device handle */
64
65         struct page     *sb_page;
66         int             sb_loaded;
67         __u64           sb_events;
68         sector_t        data_offset;    /* start of data in array */
69         sector_t        sb_start;       /* offset of the super block (in 512byte sectors) */
70         int             sb_size;        /* bytes in the superblock */
71         int             preferred_minor;        /* autorun support */
72
73         struct kobject  kobj;
74
75         /* A device can be in one of three states based on two flags:
76          * Not working:   faulty==1 in_sync==0
77          * Fully working: faulty==0 in_sync==1
78          * Working, but not
79          * in sync with array
80          *                faulty==0 in_sync==0
81          *
82          * It can never have faulty==1, in_sync==1
83          * This reduces the burden of testing multiple flags in many cases
84          */
85
86         unsigned long   flags;
87 #define Faulty          1               /* device is known to have a fault */
88 #define In_sync         2               /* device is in_sync with rest of array */
89 #define WriteMostly     4               /* Avoid reading if at all possible */
90 #define BarriersNotsupp 5               /* REQ_HARDBARRIER is not supported */
91 #define AllReserved     6               /* If whole device is reserved for
92                                          * one array */
93 #define AutoDetected    7               /* added by auto-detect */
94 #define Blocked         8               /* An error occured on an externally
95                                          * managed array, don't allow writes
96                                          * until it is cleared */
97         wait_queue_head_t blocked_wait;
98
99         int desc_nr;                    /* descriptor index in the superblock */
100         int raid_disk;                  /* role of device in array */
101         int new_raid_disk;              /* role that the device will have in
102                                          * the array after a level-change completes.
103                                          */
104         int saved_raid_disk;            /* role that device used to have in the
105                                          * array and could again if we did a partial
106                                          * resync from the bitmap
107                                          */
108         sector_t        recovery_offset;/* If this device has been partially
109                                          * recovered, this is where we were
110                                          * up to.
111                                          */
112
113         atomic_t        nr_pending;     /* number of pending requests.
114                                          * only maintained for arrays that
115                                          * support hot removal
116                                          */
117         atomic_t        read_errors;    /* number of consecutive read errors that
118                                          * we have tried to ignore.
119                                          */
120         struct timespec last_read_error;        /* monotonic time since our
121                                                  * last read error
122                                                  */
123         atomic_t        corrected_errors; /* number of corrected read errors,
124                                            * for reporting to userspace and storing
125                                            * in superblock.
126                                            */
127         struct work_struct del_work;    /* used for delayed sysfs removal */
128
129         struct sysfs_dirent *sysfs_state; /* handle for 'state'
130                                            * sysfs entry */
131 };
132
133 struct mddev_s
134 {
135         void                            *private;
136         struct mdk_personality          *pers;
137         dev_t                           unit;
138         int                             md_minor;
139         struct list_head                disks;
140         unsigned long                   flags;
141 #define MD_CHANGE_DEVS  0       /* Some device status has changed */
142 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
143 #define MD_CHANGE_PENDING 2     /* superblock update in progress */
144
145         int                             suspended;
146         atomic_t                        active_io;
147         int                             ro;
148         int                             sysfs_active; /* set when sysfs deletes
149                                                        * are happening, so run/
150                                                        * takeover/stop are not safe
151                                                        */
152
153         struct gendisk                  *gendisk;
154
155         struct kobject                  kobj;
156         int                             hold_active;
157 #define UNTIL_IOCTL     1
158 #define UNTIL_STOP      2
159
160         /* Superblock information */
161         int                             major_version,
162                                         minor_version,
163                                         patch_version;
164         int                             persistent;
165         int                             external;       /* metadata is
166                                                          * managed externally */
167         char                            metadata_type[17]; /* externally set*/
168         int                             chunk_sectors;
169         time_t                          ctime, utime;
170         int                             level, layout;
171         char                            clevel[16];
172         int                             raid_disks;
173         int                             max_disks;
174         sector_t                        dev_sectors;    /* used size of
175                                                          * component devices */
176         sector_t                        array_sectors; /* exported array size */
177         int                             external_size; /* size managed
178                                                         * externally */
179         __u64                           events;
180         /* If the last 'event' was simply a clean->dirty transition, and
181          * we didn't write it to the spares, then it is safe and simple
182          * to just decrement the event count on a dirty->clean transition.
183          * So we record that possibility here.
184          */
185         int                             can_decrease_events;
186
187         char                            uuid[16];
188
189         /* If the array is being reshaped, we need to record the
190          * new shape and an indication of where we are up to.
191          * This is written to the superblock.
192          * If reshape_position is MaxSector, then no reshape is happening (yet).
193          */
194         sector_t                        reshape_position;
195         int                             delta_disks, new_level, new_layout;
196         int                             new_chunk_sectors;
197
198         struct mdk_thread_s             *thread;        /* management thread */
199         struct mdk_thread_s             *sync_thread;   /* doing resync or reconstruct */
200         sector_t                        curr_resync;    /* last block scheduled */
201         /* As resync requests can complete out of order, we cannot easily track
202          * how much resync has been completed.  So we occasionally pause until
203          * everything completes, then set curr_resync_completed to curr_resync.
204          * As such it may be well behind the real resync mark, but it is a value
205          * we are certain of.
206          */
207         sector_t                        curr_resync_completed;
208         unsigned long                   resync_mark;    /* a recent timestamp */
209         sector_t                        resync_mark_cnt;/* blocks written at resync_mark */
210         sector_t                        curr_mark_cnt; /* blocks scheduled now */
211
212         sector_t                        resync_max_sectors; /* may be set by personality */
213
214         sector_t                        resync_mismatches; /* count of sectors where
215                                                             * parity/replica mismatch found
216                                                             */
217
218         /* allow user-space to request suspension of IO to regions of the array */
219         sector_t                        suspend_lo;
220         sector_t                        suspend_hi;
221         /* if zero, use the system-wide default */
222         int                             sync_speed_min;
223         int                             sync_speed_max;
224
225         /* resync even though the same disks are shared among md-devices */
226         int                             parallel_resync;
227
228         int                             ok_start_degraded;
229         /* recovery/resync flags 
230          * NEEDED:   we might need to start a resync/recover
231          * RUNNING:  a thread is running, or about to be started
232          * SYNC:     actually doing a resync, not a recovery
233          * RECOVER:  doing recovery, or need to try it.
234          * INTR:     resync needs to be aborted for some reason
235          * DONE:     thread is done and is waiting to be reaped
236          * REQUEST:  user-space has requested a sync (used with SYNC)
237          * CHECK:    user-space request for check-only, no repair
238          * RESHAPE:  A reshape is happening
239          *
240          * If neither SYNC or RESHAPE are set, then it is a recovery.
241          */
242 #define MD_RECOVERY_RUNNING     0
243 #define MD_RECOVERY_SYNC        1
244 #define MD_RECOVERY_RECOVER     2
245 #define MD_RECOVERY_INTR        3
246 #define MD_RECOVERY_DONE        4
247 #define MD_RECOVERY_NEEDED      5
248 #define MD_RECOVERY_REQUESTED   6
249 #define MD_RECOVERY_CHECK       7
250 #define MD_RECOVERY_RESHAPE     8
251 #define MD_RECOVERY_FROZEN      9
252
253         unsigned long                   recovery;
254         int                             recovery_disabled; /* if we detect that recovery
255                                                             * will always fail, set this
256                                                             * so we don't loop trying */
257
258         int                             in_sync;        /* know to not need resync */
259         /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
260          * that we are never stopping an array while it is open.
261          * 'reconfig_mutex' protects all other reconfiguration.
262          * These locks are separate due to conflicting interactions
263          * with bdev->bd_mutex.
264          * Lock ordering is:
265          *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
266          *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
267          */
268         struct mutex                    open_mutex;
269         struct mutex                    reconfig_mutex;
270         atomic_t                        active;         /* general refcount */
271         atomic_t                        openers;        /* number of active opens */
272
273         int                             degraded;       /* whether md should consider
274                                                          * adding a spare
275                                                          */
276         int                             barriers_work;  /* initialised to true, cleared as soon
277                                                          * as a barrier request to slave
278                                                          * fails.  Only supported
279                                                          */
280         struct bio                      *biolist;       /* bios that need to be retried
281                                                          * because REQ_HARDBARRIER is not supported
282                                                          */
283
284         atomic_t                        recovery_active; /* blocks scheduled, but not written */
285         wait_queue_head_t               recovery_wait;
286         sector_t                        recovery_cp;
287         sector_t                        resync_min;     /* user requested sync
288                                                          * starts here */
289         sector_t                        resync_max;     /* resync should pause
290                                                          * when it gets here */
291
292         struct sysfs_dirent             *sysfs_state;   /* handle for 'array_state'
293                                                          * file in sysfs.
294                                                          */
295         struct sysfs_dirent             *sysfs_action;  /* handle for 'sync_action' */
296
297         struct work_struct del_work;    /* used for delayed sysfs removal */
298
299         spinlock_t                      write_lock;
300         wait_queue_head_t               sb_wait;        /* for waiting on superblock updates */
301         atomic_t                        pending_writes; /* number of active superblock writes */
302
303         unsigned int                    safemode;       /* if set, update "clean" superblock
304                                                          * when no writes pending.
305                                                          */ 
306         unsigned int                    safemode_delay;
307         struct timer_list               safemode_timer;
308         atomic_t                        writes_pending; 
309         struct request_queue            *queue; /* for plugging ... */
310
311         struct bitmap                   *bitmap; /* the bitmap for the device */
312         struct {
313                 struct file             *file; /* the bitmap file */
314                 loff_t                  offset; /* offset from superblock of
315                                                  * start of bitmap. May be
316                                                  * negative, but not '0'
317                                                  * For external metadata, offset
318                                                  * from start of device. 
319                                                  */
320                 loff_t                  default_offset; /* this is the offset to use when
321                                                          * hot-adding a bitmap.  It should
322                                                          * eventually be settable by sysfs.
323                                                          */
324                 /* When md is serving under dm, it might use a
325                  * dirty_log to store the bits.
326                  */
327                 struct dm_dirty_log *log;
328
329                 struct mutex            mutex;
330                 unsigned long           chunksize;
331                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
332                 unsigned long           max_write_behind; /* write-behind mode */
333                 int                     external;
334         } bitmap_info;
335
336         atomic_t                        max_corr_read_errors; /* max read retries */
337         struct list_head                all_mddevs;
338
339         struct attribute_group          *to_remove;
340         struct plug_handle              *plug; /* if used by personality */
341
342         /* Generic barrier handling.
343          * If there is a pending barrier request, all other
344          * writes are blocked while the devices are flushed.
345          * The last to finish a flush schedules a worker to
346          * submit the barrier request (without the barrier flag),
347          * then submit more flush requests.
348          */
349         struct bio *barrier;
350         atomic_t flush_pending;
351         struct work_struct barrier_work;
352         struct work_struct event_work;  /* used by dm to report failure event */
353 };
354
355
356 static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
357 {
358         int faulty = test_bit(Faulty, &rdev->flags);
359         if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
360                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
361 }
362
363 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
364 {
365         atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
366 }
367
368 struct mdk_personality
369 {
370         char *name;
371         int level;
372         struct list_head list;
373         struct module *owner;
374         int (*make_request)(mddev_t *mddev, struct bio *bio);
375         int (*run)(mddev_t *mddev);
376         int (*stop)(mddev_t *mddev);
377         void (*status)(struct seq_file *seq, mddev_t *mddev);
378         /* error_handler must set ->faulty and clear ->in_sync
379          * if appropriate, and should abort recovery if needed 
380          */
381         void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
382         int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
383         int (*hot_remove_disk) (mddev_t *mddev, int number);
384         int (*spare_active) (mddev_t *mddev);
385         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
386         int (*resize) (mddev_t *mddev, sector_t sectors);
387         sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
388         int (*check_reshape) (mddev_t *mddev);
389         int (*start_reshape) (mddev_t *mddev);
390         void (*finish_reshape) (mddev_t *mddev);
391         /* quiesce moves between quiescence states
392          * 0 - fully active
393          * 1 - no new requests allowed
394          * others - reserved
395          */
396         void (*quiesce) (mddev_t *mddev, int state);
397         /* takeover is used to transition an array from one
398          * personality to another.  The new personality must be able
399          * to handle the data in the current layout.
400          * e.g. 2drive raid1 -> 2drive raid5
401          *      ndrive raid5 -> degraded n+1drive raid6 with special layout
402          * If the takeover succeeds, a new 'private' structure is returned.
403          * This needs to be installed and then ->run used to activate the
404          * array.
405          */
406         void *(*takeover) (mddev_t *mddev);
407 };
408
409
410 struct md_sysfs_entry {
411         struct attribute attr;
412         ssize_t (*show)(mddev_t *, char *);
413         ssize_t (*store)(mddev_t *, const char *, size_t);
414 };
415 extern struct attribute_group md_bitmap_group;
416
417 static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
418 {
419         if (sd)
420                 return sysfs_get_dirent(sd, NULL, name);
421         return sd;
422 }
423 static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
424 {
425         if (sd)
426                 sysfs_notify_dirent(sd);
427 }
428
429 static inline char * mdname (mddev_t * mddev)
430 {
431         return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
432 }
433
434 /*
435  * iterates through some rdev ringlist. It's safe to remove the
436  * current 'rdev'. Dont touch 'tmp' though.
437  */
438 #define rdev_for_each_list(rdev, tmp, head)                             \
439         list_for_each_entry_safe(rdev, tmp, head, same_set)
440
441 /*
442  * iterates through the 'same array disks' ringlist
443  */
444 #define rdev_for_each(rdev, tmp, mddev)                         \
445         list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
446
447 #define rdev_for_each_rcu(rdev, mddev)                          \
448         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
449
450 typedef struct mdk_thread_s {
451         void                    (*run) (mddev_t *mddev);
452         mddev_t                 *mddev;
453         wait_queue_head_t       wqueue;
454         unsigned long           flags;
455         struct task_struct      *tsk;
456         unsigned long           timeout;
457 } mdk_thread_t;
458
459 #define THREAD_WAKEUP  0
460
461 #define __wait_event_lock_irq(wq, condition, lock, cmd)                 \
462 do {                                                                    \
463         wait_queue_t __wait;                                            \
464         init_waitqueue_entry(&__wait, current);                         \
465                                                                         \
466         add_wait_queue(&wq, &__wait);                                   \
467         for (;;) {                                                      \
468                 set_current_state(TASK_UNINTERRUPTIBLE);                \
469                 if (condition)                                          \
470                         break;                                          \
471                 spin_unlock_irq(&lock);                                 \
472                 cmd;                                                    \
473                 schedule();                                             \
474                 spin_lock_irq(&lock);                                   \
475         }                                                               \
476         current->state = TASK_RUNNING;                                  \
477         remove_wait_queue(&wq, &__wait);                                \
478 } while (0)
479
480 #define wait_event_lock_irq(wq, condition, lock, cmd)                   \
481 do {                                                                    \
482         if (condition)                                                  \
483                 break;                                                  \
484         __wait_event_lock_irq(wq, condition, lock, cmd);                \
485 } while (0)
486
487 static inline void safe_put_page(struct page *p)
488 {
489         if (p) put_page(p);
490 }
491
492 extern int register_md_personality(struct mdk_personality *p);
493 extern int unregister_md_personality(struct mdk_personality *p);
494 extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
495                                 mddev_t *mddev, const char *name);
496 extern void md_unregister_thread(mdk_thread_t *thread);
497 extern void md_wakeup_thread(mdk_thread_t *thread);
498 extern void md_check_recovery(mddev_t *mddev);
499 extern void md_write_start(mddev_t *mddev, struct bio *bi);
500 extern void md_write_end(mddev_t *mddev);
501 extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
502 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
503
504 extern int mddev_congested(mddev_t *mddev, int bits);
505 extern void md_barrier_request(mddev_t *mddev, struct bio *bio);
506 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
507                            sector_t sector, int size, struct page *page);
508 extern void md_super_wait(mddev_t *mddev);
509 extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
510                         struct page *page, int rw);
511 extern void md_do_sync(mddev_t *mddev);
512 extern void md_new_event(mddev_t *mddev);
513 extern int md_allow_write(mddev_t *mddev);
514 extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
515 extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
516 extern int md_check_no_bitmap(mddev_t *mddev);
517 extern int md_integrity_register(mddev_t *mddev);
518 extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
519 extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
520 extern void restore_bitmap_write_access(struct file *file);
521 extern void md_unplug(mddev_t *mddev);
522
523 extern void mddev_init(mddev_t *mddev);
524 extern int md_run(mddev_t *mddev);
525 extern void md_stop(mddev_t *mddev);
526 extern void md_stop_writes(mddev_t *mddev);
527 extern void md_rdev_init(mdk_rdev_t *rdev);
528
529 extern void mddev_suspend(mddev_t *mddev);
530 extern void mddev_resume(mddev_t *mddev);
531 #endif /* _MD_MD_H */