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1/*
2 * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
3 *
4 * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
5 */
6#ifndef BITMAP_H
7#define BITMAP_H 1
8
9#define BITMAP_MAJOR_LO 3
10/* version 4 insists the bitmap is in little-endian order
11 * with version 3, it is host-endian which is non-portable
12 */
13#define BITMAP_MAJOR_HI 4
14#define BITMAP_MAJOR_HOSTENDIAN 3
15
16#define BITMAP_MINOR 39
17
18/*
19 * in-memory bitmap:
20 *
21 * Use 16 bit block counters to track pending writes to each "chunk".
22 * The 2 high order bits are special-purpose, the first is a flag indicating
23 * whether a resync is needed. The second is a flag indicating whether a
24 * resync is active.
25 * This means that the counter is actually 14 bits:
26 *
27 * +--------+--------+------------------------------------------------+
28 * | resync | resync | counter |
29 * | needed | active | |
30 * | (0-1) | (0-1) | (0-16383) |
31 * +--------+--------+------------------------------------------------+
32 *
33 * The "resync needed" bit is set when:
34 * a '1' bit is read from storage at startup.
35 * a write request fails on some drives
36 * a resync is aborted on a chunk with 'resync active' set
37 * It is cleared (and resync-active set) when a resync starts across all drives
38 * of the chunk.
39 *
40 *
41 * The "resync active" bit is set when:
42 * a resync is started on all drives, and resync_needed is set.
43 * resync_needed will be cleared (as long as resync_active wasn't already set).
44 * It is cleared when a resync completes.
45 *
46 * The counter counts pending write requests, plus the on-disk bit.
47 * When the counter is '1' and the resync bits are clear, the on-disk
48 * bit can be cleared as well, thus setting the counter to 0.
49 * When we set a bit, or in the counter (to start a write), if the fields is
50 * 0, we first set the disk bit and set the counter to 1.
51 *
52 * If the counter is 0, the on-disk bit is clear and the stipe is clean
53 * Anything that dirties the stipe pushes the counter to 2 (at least)
54 * and sets the on-disk bit (lazily).
55 * If a periodic sweep find the counter at 2, it is decremented to 1.
56 * If the sweep find the counter at 1, the on-disk bit is cleared and the
57 * counter goes to zero.
58 *
59 * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
60 * counters as a fallback when "page" memory cannot be allocated:
61 *
62 * Normal case (page memory allocated):
63 *
64 * page pointer (32-bit)
65 *
66 * [ ] ------+
67 * |
68 * +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters)
69 * c1 c2 c2048
70 *
71 * Hijacked case (page memory allocation failed):
72 *
73 * hijacked page pointer (32-bit)
74 *
75 * [ ][ ] (no page memory allocated)
76 * counter #1 (16-bit) counter #2 (16-bit)
77 *
78 */
79
80#ifdef __KERNEL__
81
82#define PAGE_BITS (PAGE_SIZE << 3)
83#define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)
84
85typedef __u16 bitmap_counter_t;
86#define COUNTER_BITS 16
87#define COUNTER_BIT_SHIFT 4
88#define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3)
89
90#define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1)))
91#define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2)))
92#define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1)
93#define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK)
94#define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK)
95#define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX)
96
97/* how many counters per page? */
98#define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS)
99/* same, except a shift value for more efficient bitops */
100#define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT)
101/* same, except a mask value for more efficient bitops */
102#define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1)
103
104#define BITMAP_BLOCK_SIZE 512
105#define BITMAP_BLOCK_SHIFT 9
106
107/* how many blocks per chunk? (this is variable) */
108#define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->mddev->bitmap_info.chunksize >> BITMAP_BLOCK_SHIFT)
109#define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT)
110#define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1)
111
112/* when hijacked, the counters and bits represent even larger "chunks" */
113/* there will be 1024 chunks represented by each counter in the page pointers */
114#define PAGEPTR_BLOCK_RATIO(bitmap) \
115 (CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1)
116#define PAGEPTR_BLOCK_SHIFT(bitmap) \
117 (CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
118#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)
119
120#endif
121
122/*
123 * bitmap structures:
124 */
125
126#define BITMAP_MAGIC 0x6d746962
127
128/* use these for bitmap->flags and bitmap->sb->state bit-fields */
129enum bitmap_state {
130 BITMAP_STALE = 0x002, /* the bitmap file is out of date or had -EIO */
131 BITMAP_WRITE_ERROR = 0x004, /* A write error has occurred */
132 BITMAP_HOSTENDIAN = 0x8000,
133};
134
135/* the superblock at the front of the bitmap file -- little endian */
136typedef struct bitmap_super_s {
137 __le32 magic; /* 0 BITMAP_MAGIC */
138 __le32 version; /* 4 the bitmap major for now, could change... */
139 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */
140 __le64 events; /* 24 event counter for the bitmap (1)*/
141 __le64 events_cleared;/*32 event counter when last bit cleared (2) */
142 __le64 sync_size; /* 40 the size of the md device's sync range(3) */
143 __le32 state; /* 48 bitmap state information */
144 __le32 chunksize; /* 52 the bitmap chunk size in bytes */
145 __le32 daemon_sleep; /* 56 seconds between disk flushes */
146 __le32 write_behind; /* 60 number of outstanding write-behind writes */
147
148 __u8 pad[256 - 64]; /* set to zero */
149} bitmap_super_t;
150
151/* notes:
152 * (1) This event counter is updated before the eventcounter in the md superblock
153 * When a bitmap is loaded, it is only accepted if this event counter is equal
154 * to, or one greater than, the event counter in the superblock.
155 * (2) This event counter is updated when the other one is *if*and*only*if* the
156 * array is not degraded. As bits are not cleared when the array is degraded,
157 * this represents the last time that any bits were cleared.
158 * If a device is being added that has an event count with this value or
159 * higher, it is accepted as conforming to the bitmap.
160 * (3)This is the number of sectors represented by the bitmap, and is the range that
161 * resync happens across. For raid1 and raid5/6 it is the size of individual
162 * devices. For raid10 it is the size of the array.
163 */
164
165#ifdef __KERNEL__
166
167/* the in-memory bitmap is represented by bitmap_pages */
168struct bitmap_page {
169 /*
170 * map points to the actual memory page
171 */
172 char *map;
173 /*
174 * in emergencies (when map cannot be alloced), hijack the map
175 * pointer and use it as two counters itself
176 */
177 unsigned int hijacked:1;
178 /*
179 * count of dirty bits on the page
180 */
181 unsigned int count:31;
182};
183
184/* keep track of bitmap file pages that have pending writes on them */
185struct page_list {
186 struct list_head list;
187 struct page *page;
188};
189
190/* the main bitmap structure - one per mddev */
191struct bitmap {
192 struct bitmap_page *bp;
193 unsigned long pages; /* total number of pages in the bitmap */
194 unsigned long missing_pages; /* number of pages not yet allocated */
195
196 mddev_t *mddev; /* the md device that the bitmap is for */
197
198 /* bitmap chunksize -- how much data does each bit represent? */
199 unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */
200 unsigned long chunks; /* total number of data chunks for the array */
201
202 __u64 events_cleared;
203 int need_sync;
204
205 /* bitmap spinlock */
206 spinlock_t lock;
207
208 struct file *file; /* backing disk file */
209 struct page *sb_page; /* cached copy of the bitmap file superblock */
210 struct page **filemap; /* list of cache pages for the file */
211 unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
212 unsigned long file_pages; /* number of pages in the file */
213 int last_page_size; /* bytes in the last page */
214
215 unsigned long flags;
216
217 int allclean;
218
219 atomic_t behind_writes;
220 unsigned long behind_writes_used; /* highest actual value at runtime */
221
222 /*
223 * the bitmap daemon - periodically wakes up and sweeps the bitmap
224 * file, cleaning up bits and flushing out pages to disk as necessary
225 */
226 unsigned long daemon_lastrun; /* jiffies of last run */
227 unsigned long last_end_sync; /* when we lasted called end_sync to
228 * update bitmap with resync progress */
229
230 atomic_t pending_writes; /* pending writes to the bitmap file */
231 wait_queue_head_t write_wait;
232 wait_queue_head_t overflow_wait;
233 wait_queue_head_t behind_wait;
234
235 struct sysfs_dirent *sysfs_can_clear;
236};
237
238/* the bitmap API */
239
240/* these are used only by md/bitmap */
241int bitmap_create(mddev_t *mddev);
242int bitmap_load(mddev_t *mddev);
243void bitmap_flush(mddev_t *mddev);
244void bitmap_destroy(mddev_t *mddev);
245
246void bitmap_print_sb(struct bitmap *bitmap);
247void bitmap_update_sb(struct bitmap *bitmap);
248
249int bitmap_setallbits(struct bitmap *bitmap);
250void bitmap_write_all(struct bitmap *bitmap);
251
252void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
253
254/* these are exported */
255int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
256 unsigned long sectors, int behind);
257void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
258 unsigned long sectors, int success, int behind);
259int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
260void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
261void bitmap_close_sync(struct bitmap *bitmap);
262void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector);
263
264void bitmap_unplug(struct bitmap *bitmap);
265void bitmap_daemon_work(mddev_t *mddev);
266#endif
267
268#endif