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c82f047c NB |
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 | ||
dcec9ee5 NB |
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 | ||
dfd4d8ee | 16 | #define BITMAP_MINOR 39 |
c82f047c NB |
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 aswell, 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 | * | |
dfd4d8ee NB |
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 | * | |
c82f047c NB |
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 | ||
85 | typedef __u16 bitmap_counter_t; | |
86 | #define COUNTER_BITS 16 | |
87 | #define COUNTER_BIT_SHIFT 4 | |
88 | #define COUNTER_BYTE_RATIO (COUNTER_BITS / 8) | |
89 | #define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3) | |
90 | ||
91 | #define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1))) | |
92 | #define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2))) | |
93 | #define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1) | |
94 | #define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK) | |
95 | #define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK) | |
96 | #define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX) | |
97 | ||
98 | /* how many counters per page? */ | |
99 | #define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS) | |
100 | /* same, except a shift value for more efficient bitops */ | |
101 | #define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT) | |
102 | /* same, except a mask value for more efficient bitops */ | |
103 | #define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1) | |
104 | ||
105 | #define BITMAP_BLOCK_SIZE 512 | |
106 | #define BITMAP_BLOCK_SHIFT 9 | |
107 | ||
108 | /* how many blocks per chunk? (this is variable) */ | |
109 | #define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->chunksize >> BITMAP_BLOCK_SHIFT) | |
110 | #define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT) | |
111 | #define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1) | |
112 | ||
113 | /* when hijacked, the counters and bits represent even larger "chunks" */ | |
114 | /* there will be 1024 chunks represented by each counter in the page pointers */ | |
115 | #define PAGEPTR_BLOCK_RATIO(bitmap) \ | |
116 | (CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1) | |
117 | #define PAGEPTR_BLOCK_SHIFT(bitmap) \ | |
118 | (CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1) | |
119 | #define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1) | |
120 | ||
121 | /* | |
122 | * on-disk bitmap: | |
123 | * | |
124 | * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap | |
125 | * file a page at a time. There's a superblock at the start of the file. | |
126 | */ | |
127 | ||
128 | /* map chunks (bits) to file pages - offset by the size of the superblock */ | |
129 | #define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3)) | |
130 | ||
131 | #endif | |
132 | ||
133 | /* | |
134 | * bitmap structures: | |
135 | */ | |
136 | ||
137 | #define BITMAP_MAGIC 0x6d746962 | |
138 | ||
139 | /* use these for bitmap->flags and bitmap->sb->state bit-fields */ | |
140 | enum bitmap_state { | |
141 | BITMAP_ACTIVE = 0x001, /* the bitmap is in use */ | |
142 | BITMAP_STALE = 0x002 /* the bitmap file is out of date or had -EIO */ | |
143 | }; | |
144 | ||
145 | /* the superblock at the front of the bitmap file -- little endian */ | |
146 | typedef struct bitmap_super_s { | |
147 | __u32 magic; /* 0 BITMAP_MAGIC */ | |
148 | __u32 version; /* 4 the bitmap major for now, could change... */ | |
149 | __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */ | |
150 | __u64 events; /* 24 event counter for the bitmap (1)*/ | |
151 | __u64 events_cleared;/*32 event counter when last bit cleared (2) */ | |
152 | __u64 sync_size; /* 40 the size of the md device's sync range(3) */ | |
153 | __u32 state; /* 48 bitmap state information */ | |
154 | __u32 chunksize; /* 52 the bitmap chunk size in bytes */ | |
155 | __u32 daemon_sleep; /* 56 seconds between disk flushes */ | |
dfd4d8ee | 156 | __u32 write_behind; /* 60 number of outstanding write-behind writes */ |
c82f047c | 157 | |
dfd4d8ee | 158 | __u8 pad[256 - 64]; /* set to zero */ |
c82f047c NB |
159 | } bitmap_super_t; |
160 | ||
161 | /* notes: | |
162 | * (1) This event counter is updated before the eventcounter in the md superblock | |
163 | * When a bitmap is loaded, it is only accepted if this event counter is equal | |
164 | * to, or one greater than, the event counter in the superblock. | |
aba69144 | 165 | * (2) This event counter is updated when the other one is *if*and*only*if* the |
c82f047c NB |
166 | * array is not degraded. As bits are not cleared when the array is degraded, |
167 | * this represents the last time that any bits were cleared. | |
168 | * If a device is being added that has an event count with this value or | |
169 | * higher, it is accepted as conforming to the bitmap. | |
170 | * (3)This is the number of sectors represented by the bitmap, and is the range that | |
171 | * resync happens across. For raid1 and raid5/6 it is the size of individual | |
172 | * devices. For raid10 it is the size of the array. | |
173 | */ | |
174 | ||
175 | #ifdef __KERNEL__ | |
176 | ||
177 | /* the in-memory bitmap is represented by bitmap_pages */ | |
178 | struct bitmap_page { | |
179 | /* | |
180 | * map points to the actual memory page | |
181 | */ | |
182 | char *map; | |
183 | /* | |
184 | * in emergencies (when map cannot be alloced), hijack the map | |
185 | * pointer and use it as two counters itself | |
186 | */ | |
187 | unsigned int hijacked; | |
188 | /* | |
189 | * count of dirty bits on the page | |
aba69144 | 190 | */ |
c82f047c NB |
191 | int count; |
192 | }; | |
193 | ||
194 | /* keep track of bitmap file pages that have pending writes on them */ | |
195 | struct page_list { | |
196 | struct list_head list; | |
197 | struct page *page; | |
198 | }; | |
199 | ||
200 | /* the main bitmap structure - one per mddev */ | |
201 | struct bitmap { | |
202 | struct bitmap_page *bp; | |
203 | unsigned long pages; /* total number of pages in the bitmap */ | |
204 | unsigned long missing_pages; /* number of pages not yet allocated */ | |
205 | ||
206 | mddev_t *mddev; /* the md device that the bitmap is for */ | |
207 | ||
208 | int counter_bits; /* how many bits per block counter */ | |
209 | ||
210 | /* bitmap chunksize -- how much data does each bit represent? */ | |
211 | unsigned long chunksize; | |
212 | unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */ | |
213 | unsigned long chunks; /* total number of data chunks for the array */ | |
214 | ||
215 | /* We hold a count on the chunk currently being synced, and drop | |
216 | * it when the last block is started. If the resync is aborted | |
217 | * midway, we need to be able to drop that count, so we remember | |
218 | * the counted chunk.. | |
219 | */ | |
220 | unsigned long syncchunk; | |
221 | ||
222 | __u64 events_cleared; | |
223 | ||
224 | /* bitmap spinlock */ | |
225 | spinlock_t lock; | |
226 | ||
227 | struct file *file; /* backing disk file */ | |
228 | struct page *sb_page; /* cached copy of the bitmap file superblock */ | |
229 | struct page **filemap; /* list of cache pages for the file */ | |
230 | unsigned long *filemap_attr; /* attributes associated w/ filemap pages */ | |
231 | unsigned long file_pages; /* number of pages in the file */ | |
232 | ||
233 | unsigned long flags; | |
234 | ||
235 | /* | |
236 | * the bitmap daemon - periodically wakes up and sweeps the bitmap | |
237 | * file, cleaning up bits and flushing out pages to disk as necessary | |
238 | */ | |
239 | mdk_thread_t *daemon; | |
240 | unsigned long daemon_sleep; /* how many seconds between updates? */ | |
241 | ||
242 | /* | |
243 | * bitmap write daemon - this daemon performs writes to the bitmap file | |
244 | * this thread is only needed because of a limitation in ext3 (jbd) | |
245 | * that does not allow a task to have two journal transactions ongoing | |
246 | * simultaneously (even if the transactions are for two different | |
247 | * filesystems) -- in the case of bitmap, that would be the filesystem | |
248 | * that the bitmap file resides on and the filesystem that is mounted | |
249 | * on the md device -- see current->journal_info in jbd/transaction.c | |
250 | */ | |
251 | mdk_thread_t *write_daemon; | |
252 | mdk_thread_t *writeback_daemon; | |
253 | spinlock_t write_lock; | |
254 | struct semaphore write_ready; | |
255 | struct semaphore write_done; | |
256 | unsigned long writes_pending; | |
257 | wait_queue_head_t write_wait; | |
258 | struct list_head write_pages; | |
259 | struct list_head complete_pages; | |
260 | mempool_t *write_pool; | |
261 | }; | |
262 | ||
263 | /* the bitmap API */ | |
264 | ||
265 | /* these are used only by md/bitmap */ | |
266 | int bitmap_create(mddev_t *mddev); | |
267 | void bitmap_destroy(mddev_t *mddev); | |
268 | int bitmap_active(struct bitmap *bitmap); | |
269 | ||
270 | char *file_path(struct file *file, char *buf, int count); | |
271 | void bitmap_print_sb(struct bitmap *bitmap); | |
272 | int bitmap_update_sb(struct bitmap *bitmap); | |
273 | ||
274 | int bitmap_setallbits(struct bitmap *bitmap); | |
275 | ||
276 | /* these are exported */ | |
277 | void bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors); | |
278 | void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, | |
279 | int success); | |
280 | int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks); | |
281 | void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted); | |
282 | void bitmap_close_sync(struct bitmap *bitmap); | |
283 | ||
284 | int bitmap_unplug(struct bitmap *bitmap); | |
285 | #endif | |
286 | ||
287 | #endif |