ACPI: pci_root: simplify list traversals
[linux-2.6/linux-acpi-2.6.git] / drivers / md / bitmap.h
blobe98900671ca91d7a4f76ae91ac7393f6613bd5ee
1 /*
2 * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
4 * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
5 */
6 #ifndef BITMAP_H
7 #define BITMAP_H 1
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
13 #define BITMAP_MAJOR_HI 4
14 #define BITMAP_MAJOR_HOSTENDIAN 3
16 #define BITMAP_MINOR 39
19 * in-memory bitmap:
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:
27 * +--------+--------+------------------------------------------------+
28 * | resync | resync | counter |
29 * | needed | active | |
30 * | (0-1) | (0-1) | (0-16383) |
31 * +--------+--------+------------------------------------------------+
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.
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.
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.
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.
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:
62 * Normal case (page memory allocated):
64 * page pointer (32-bit)
66 * [ ] ------+
67 * |
68 * +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters)
69 * c1 c2 c2048
71 * Hijacked case (page memory allocation failed):
73 * hijacked page pointer (32-bit)
75 * [ ][ ] (no page memory allocated)
76 * counter #1 (16-bit) counter #2 (16-bit)
80 #ifdef __KERNEL__
82 #define PAGE_BITS (PAGE_SIZE << 3)
83 #define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)
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)
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)
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)
105 #define BITMAP_BLOCK_SIZE 512
106 #define BITMAP_BLOCK_SHIFT 9
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)
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)
122 * on-disk bitmap:
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.
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))
131 #endif
134 * bitmap structures:
137 #define BITMAP_MAGIC 0x6d746962
139 /* use these for bitmap->flags and bitmap->sb->state bit-fields */
140 enum bitmap_state {
141 BITMAP_STALE = 0x002, /* the bitmap file is out of date or had -EIO */
142 BITMAP_WRITE_ERROR = 0x004, /* A write error has occurred */
143 BITMAP_HOSTENDIAN = 0x8000,
146 /* the superblock at the front of the bitmap file -- little endian */
147 typedef struct bitmap_super_s {
148 __le32 magic; /* 0 BITMAP_MAGIC */
149 __le32 version; /* 4 the bitmap major for now, could change... */
150 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */
151 __le64 events; /* 24 event counter for the bitmap (1)*/
152 __le64 events_cleared;/*32 event counter when last bit cleared (2) */
153 __le64 sync_size; /* 40 the size of the md device's sync range(3) */
154 __le32 state; /* 48 bitmap state information */
155 __le32 chunksize; /* 52 the bitmap chunk size in bytes */
156 __le32 daemon_sleep; /* 56 seconds between disk flushes */
157 __le32 write_behind; /* 60 number of outstanding write-behind writes */
159 __u8 pad[256 - 64]; /* set to zero */
160 } bitmap_super_t;
162 /* notes:
163 * (1) This event counter is updated before the eventcounter in the md superblock
164 * When a bitmap is loaded, it is only accepted if this event counter is equal
165 * to, or one greater than, the event counter in the superblock.
166 * (2) This event counter is updated when the other one is *if*and*only*if* the
167 * array is not degraded. As bits are not cleared when the array is degraded,
168 * this represents the last time that any bits were cleared.
169 * If a device is being added that has an event count with this value or
170 * higher, it is accepted as conforming to the bitmap.
171 * (3)This is the number of sectors represented by the bitmap, and is the range that
172 * resync happens across. For raid1 and raid5/6 it is the size of individual
173 * devices. For raid10 it is the size of the array.
176 #ifdef __KERNEL__
178 /* the in-memory bitmap is represented by bitmap_pages */
179 struct bitmap_page {
181 * map points to the actual memory page
183 char *map;
185 * in emergencies (when map cannot be alloced), hijack the map
186 * pointer and use it as two counters itself
188 unsigned int hijacked:1;
190 * count of dirty bits on the page
192 unsigned int count:31;
195 /* keep track of bitmap file pages that have pending writes on them */
196 struct page_list {
197 struct list_head list;
198 struct page *page;
201 /* the main bitmap structure - one per mddev */
202 struct bitmap {
203 struct bitmap_page *bp;
204 unsigned long pages; /* total number of pages in the bitmap */
205 unsigned long missing_pages; /* number of pages not yet allocated */
207 mddev_t *mddev; /* the md device that the bitmap is for */
209 int counter_bits; /* how many bits per block counter */
211 /* bitmap chunksize -- how much data does each bit represent? */
212 unsigned long chunksize;
213 unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */
214 unsigned long chunks; /* total number of data chunks for the array */
216 /* We hold a count on the chunk currently being synced, and drop
217 * it when the last block is started. If the resync is aborted
218 * midway, we need to be able to drop that count, so we remember
219 * the counted chunk..
221 unsigned long syncchunk;
223 __u64 events_cleared;
224 int need_sync;
226 /* bitmap spinlock */
227 spinlock_t lock;
229 long offset; /* offset from superblock if file is NULL */
230 struct file *file; /* backing disk file */
231 struct page *sb_page; /* cached copy of the bitmap file superblock */
232 struct page **filemap; /* list of cache pages for the file */
233 unsigned long *filemap_attr; /* attributes associated w/ filemap pages */
234 unsigned long file_pages; /* number of pages in the file */
235 int last_page_size; /* bytes in the last page */
237 unsigned long flags;
239 int allclean;
241 unsigned long max_write_behind; /* write-behind mode */
242 atomic_t behind_writes;
245 * the bitmap daemon - periodically wakes up and sweeps the bitmap
246 * file, cleaning up bits and flushing out pages to disk as necessary
248 unsigned long daemon_lastrun; /* jiffies of last run */
249 unsigned long daemon_sleep; /* how many seconds between updates? */
250 unsigned long last_end_sync; /* when we lasted called end_sync to
251 * update bitmap with resync progress */
253 atomic_t pending_writes; /* pending writes to the bitmap file */
254 wait_queue_head_t write_wait;
255 wait_queue_head_t overflow_wait;
259 /* the bitmap API */
261 /* these are used only by md/bitmap */
262 int bitmap_create(mddev_t *mddev);
263 void bitmap_flush(mddev_t *mddev);
264 void bitmap_destroy(mddev_t *mddev);
266 void bitmap_print_sb(struct bitmap *bitmap);
267 void bitmap_update_sb(struct bitmap *bitmap);
269 int bitmap_setallbits(struct bitmap *bitmap);
270 void bitmap_write_all(struct bitmap *bitmap);
272 void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
274 /* these are exported */
275 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
276 unsigned long sectors, int behind);
277 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
278 unsigned long sectors, int success, int behind);
279 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int degraded);
280 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted);
281 void bitmap_close_sync(struct bitmap *bitmap);
282 void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector);
284 void bitmap_unplug(struct bitmap *bitmap);
285 void bitmap_daemon_work(struct bitmap *bitmap);
286 #endif
288 #endif