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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
bd926c63
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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
3c462c88 12 * Version 5 is currently set only for clustered devices
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13 */
14#define BITMAP_MAJOR_HI 4
3c462c88 15#define BITMAP_MAJOR_CLUSTERED 5
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16#define BITMAP_MAJOR_HOSTENDIAN 3
17
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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
25985edc 48 * bit can be cleared as well, thus setting the counter to 0.
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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 *
d85326cf
GJ
52 * If the counter is 0, the on-disk bit is clear and the stripe is clean
53 * Anything that dirties the stripe pushes the counter to 2 (at least)
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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
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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
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104#define BITMAP_BLOCK_SHIFT 9
105
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106#endif
107
108/*
109 * bitmap structures:
110 */
111
112#define BITMAP_MAGIC 0x6d746962
113
114/* use these for bitmap->flags and bitmap->sb->state bit-fields */
115enum bitmap_state {
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116 BITMAP_STALE = 1, /* the bitmap file is out of date or had -EIO */
117 BITMAP_WRITE_ERROR = 2, /* A write error has occurred */
118 BITMAP_HOSTENDIAN =15,
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119};
120
121/* the superblock at the front of the bitmap file -- little endian */
122typedef struct bitmap_super_s {
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123 __le32 magic; /* 0 BITMAP_MAGIC */
124 __le32 version; /* 4 the bitmap major for now, could change... */
125 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */
126 __le64 events; /* 24 event counter for the bitmap (1)*/
127 __le64 events_cleared;/*32 event counter when last bit cleared (2) */
128 __le64 sync_size; /* 40 the size of the md device's sync range(3) */
129 __le32 state; /* 48 bitmap state information */
130 __le32 chunksize; /* 52 the bitmap chunk size in bytes */
131 __le32 daemon_sleep; /* 56 seconds between disk flushes */
132 __le32 write_behind; /* 60 number of outstanding write-behind writes */
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133 __le32 sectors_reserved; /* 64 number of 512-byte sectors that are
134 * reserved for the bitmap. */
183bdf51 135 __le32 nodes; /* 68 the maximum number of nodes in cluster. */
cf921cc1
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136 __u8 cluster_name[64]; /* 72 cluster name to which this md belongs */
137 __u8 pad[256 - 136]; /* set to zero */
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138} bitmap_super_t;
139
140/* notes:
141 * (1) This event counter is updated before the eventcounter in the md superblock
142 * When a bitmap is loaded, it is only accepted if this event counter is equal
143 * to, or one greater than, the event counter in the superblock.
144 * (2) This event counter is updated when the other one is *if*and*only*if* the
145 * array is not degraded. As bits are not cleared when the array is degraded,
146 * this represents the last time that any bits were cleared.
147 * If a device is being added that has an event count with this value or
148 * higher, it is accepted as conforming to the bitmap.
149 * (3)This is the number of sectors represented by the bitmap, and is the range that
150 * resync happens across. For raid1 and raid5/6 it is the size of individual
151 * devices. For raid10 it is the size of the array.
152 */
153
154#ifdef __KERNEL__
155
156/* the in-memory bitmap is represented by bitmap_pages */
157struct bitmap_page {
158 /*
159 * map points to the actual memory page
160 */
161 char *map;
162 /*
163 * in emergencies (when map cannot be alloced), hijack the map
164 * pointer and use it as two counters itself
165 */
166 unsigned int hijacked:1;
bf07bb7d
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167 /*
168 * If any counter in this page is '1' or '2' - and so could be
169 * cleared then that page is marked as 'pending'
170 */
171 unsigned int pending:1;
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172 /*
173 * count of dirty bits on the page
174 */
bf07bb7d 175 unsigned int count:30;
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176};
177
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178/* the main bitmap structure - one per mddev */
179struct bitmap {
32a7627c 180
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181 struct bitmap_counts {
182 spinlock_t lock;
183 struct bitmap_page *bp;
184 unsigned long pages; /* total number of pages
185 * in the bitmap */
186 unsigned long missing_pages; /* number of pages
187 * not yet allocated */
188 unsigned long chunkshift; /* chunksize = 2^chunkshift
189 * (for bitops) */
190 unsigned long chunks; /* Total number of data
191 * chunks for the array */
192 } counts;
32a7627c 193
40cffcc0 194 struct mddev *mddev; /* the md device that the bitmap is for */
32a7627c 195
32a7627c 196 __u64 events_cleared;
a0da84f3 197 int need_sync;
32a7627c 198
1ec885cd
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199 struct bitmap_storage {
200 struct file *file; /* backing disk file */
201 struct page *sb_page; /* cached copy of the bitmap
202 * file superblock */
203 struct page **filemap; /* list of cache pages for
204 * the file */
205 unsigned long *filemap_attr; /* attributes associated
206 * w/ filemap pages */
207 unsigned long file_pages; /* number of pages in the file*/
9b1215c1 208 unsigned long bytes; /* total bytes in the bitmap */
1ec885cd 209 } storage;
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210
211 unsigned long flags;
212
8311c29d
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213 int allclean;
214
4b6d287f 215 atomic_t behind_writes;
696fcd53 216 unsigned long behind_writes_used; /* highest actual value at runtime */
4b6d287f 217
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218 /*
219 * the bitmap daemon - periodically wakes up and sweeps the bitmap
220 * file, cleaning up bits and flushing out pages to disk as necessary
221 */
222 unsigned long daemon_lastrun; /* jiffies of last run */
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223 unsigned long last_end_sync; /* when we lasted called end_sync to
224 * update bitmap with resync progress */
32a7627c 225
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226 atomic_t pending_writes; /* pending writes to the bitmap file */
227 wait_queue_head_t write_wait;
da6e1a32 228 wait_queue_head_t overflow_wait;
e555190d 229 wait_queue_head_t behind_wait;
d785a06a 230
324a56e1 231 struct kernfs_node *sysfs_can_clear;
b97e9257 232 int cluster_slot; /* Slot offset for clustered env */
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233};
234
235/* the bitmap API */
236
237/* these are used only by md/bitmap */
f9209a32 238struct bitmap *bitmap_create(struct mddev *mddev, int slot);
fd01b88c
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239int bitmap_load(struct mddev *mddev);
240void bitmap_flush(struct mddev *mddev);
241void bitmap_destroy(struct mddev *mddev);
32a7627c 242
32a7627c 243void bitmap_print_sb(struct bitmap *bitmap);
4ad13663 244void bitmap_update_sb(struct bitmap *bitmap);
57148964 245void bitmap_status(struct seq_file *seq, struct bitmap *bitmap);
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246
247int bitmap_setallbits(struct bitmap *bitmap);
a654b9d8 248void bitmap_write_all(struct bitmap *bitmap);
32a7627c 249
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250void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
251
32a7627c 252/* these are exported */
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253int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
254 unsigned long sectors, int behind);
255void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
256 unsigned long sectors, int success, int behind);
57dab0bd
N
257int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
258void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
32a7627c 259void bitmap_close_sync(struct bitmap *bitmap);
c40f341f 260void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force);
18c9ff7f
GJ
261void bitmap_sync_with_cluster(struct mddev *mddev,
262 sector_t old_lo, sector_t old_hi,
263 sector_t new_lo, sector_t new_hi);
32a7627c 264
4ad13663 265void bitmap_unplug(struct bitmap *bitmap);
fd01b88c 266void bitmap_daemon_work(struct mddev *mddev);
d60b479d
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267
268int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
269 int chunksize, int init);
11dd35da 270int bitmap_copy_from_slot(struct mddev *mddev, int slot,
97f6cd39 271 sector_t *lo, sector_t *hi, bool clear_bits);
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272#endif
273
274#endif