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