1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003
4  *
5  * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
6  */
7 #ifndef BITMAP_H
8 #define BITMAP_H 1
9 
10 #define BITMAP_MAJOR_LO 3
11 /* version 4 insists the bitmap is in little-endian order
12  * with version 3, it is host-endian which is non-portable
13  * Version 5 is currently set only for clustered devices
14  */
15 #define BITMAP_MAJOR_HI 4
16 #define BITMAP_MAJOR_CLUSTERED 5
17 #define	BITMAP_MAJOR_HOSTENDIAN 3
18 
19 /*
20  * in-memory bitmap:
21  *
22  * Use 16 bit block counters to track pending writes to each "chunk".
23  * The 2 high order bits are special-purpose, the first is a flag indicating
24  * whether a resync is needed.  The second is a flag indicating whether a
25  * resync is active.
26  * This means that the counter is actually 14 bits:
27  *
28  * +--------+--------+------------------------------------------------+
29  * | resync | resync |               counter                          |
30  * | needed | active |                                                |
31  * |  (0-1) |  (0-1) |              (0-16383)                         |
32  * +--------+--------+------------------------------------------------+
33  *
34  * The "resync needed" bit is set when:
35  *    a '1' bit is read from storage at startup.
36  *    a write request fails on some drives
37  *    a resync is aborted on a chunk with 'resync active' set
38  * It is cleared (and resync-active set) when a resync starts across all drives
39  * of the chunk.
40  *
41  *
42  * The "resync active" bit is set when:
43  *    a resync is started on all drives, and resync_needed is set.
44  *       resync_needed will be cleared (as long as resync_active wasn't already set).
45  * It is cleared when a resync completes.
46  *
47  * The counter counts pending write requests, plus the on-disk bit.
48  * When the counter is '1' and the resync bits are clear, the on-disk
49  * bit can be cleared as well, thus setting the counter to 0.
50  * When we set a bit, or in the counter (to start a write), if the fields is
51  * 0, we first set the disk bit and set the counter to 1.
52  *
53  * If the counter is 0, the on-disk bit is clear and the stripe is clean
54  * Anything that dirties the stripe pushes the counter to 2 (at least)
55  * and sets the on-disk bit (lazily).
56  * If a periodic sweep find the counter at 2, it is decremented to 1.
57  * If the sweep find the counter at 1, the on-disk bit is cleared and the
58  * counter goes to zero.
59  *
60  * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
61  * counters as a fallback when "page" memory cannot be allocated:
62  *
63  * Normal case (page memory allocated):
64  *
65  *     page pointer (32-bit)
66  *
67  *     [ ] ------+
68  *               |
69  *               +-------> [   ][   ]..[   ] (4096 byte page == 2048 counters)
70  *                          c1   c2    c2048
71  *
72  * Hijacked case (page memory allocation failed):
73  *
74  *     hijacked page pointer (32-bit)
75  *
76  *     [		  ][		  ] (no page memory allocated)
77  *      counter #1 (16-bit) counter #2 (16-bit)
78  *
79  */
80 
81 #ifdef __KERNEL__
82 
83 #define PAGE_BITS (PAGE_SIZE << 3)
84 #define PAGE_BIT_SHIFT (PAGE_SHIFT + 3)
85 
86 typedef __u16 bitmap_counter_t;
87 #define COUNTER_BITS 16
88 #define COUNTER_BIT_SHIFT 4
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_SHIFT 9
106 
107 #endif
108 
109 /*
110  * bitmap structures:
111  */
112 
113 #define BITMAP_MAGIC 0x6d746962
114 
115 /* use these for bitmap->flags and bitmap->sb->state bit-fields */
116 enum bitmap_state {
117 	BITMAP_STALE	   = 1,  /* the bitmap file is out of date or had -EIO */
118 	BITMAP_WRITE_ERROR = 2, /* A write error has occurred */
119 	BITMAP_HOSTENDIAN  =15,
120 };
121 
122 /* the superblock at the front of the bitmap file -- little endian */
123 typedef struct bitmap_super_s {
124 	__le32 magic;        /*  0  BITMAP_MAGIC */
125 	__le32 version;      /*  4  the bitmap major for now, could change... */
126 	__u8  uuid[16];      /*  8  128 bit uuid - must match md device uuid */
127 	__le64 events;       /* 24  event counter for the bitmap (1)*/
128 	__le64 events_cleared;/*32  event counter when last bit cleared (2) */
129 	__le64 sync_size;    /* 40  the size of the md device's sync range(3) */
130 	__le32 state;        /* 48  bitmap state information */
131 	__le32 chunksize;    /* 52  the bitmap chunk size in bytes */
132 	__le32 daemon_sleep; /* 56  seconds between disk flushes */
133 	__le32 write_behind; /* 60  number of outstanding write-behind writes */
134 	__le32 sectors_reserved; /* 64 number of 512-byte sectors that are
135 				  * reserved for the bitmap. */
136 	__le32 nodes;        /* 68 the maximum number of nodes in cluster. */
137 	__u8 cluster_name[64]; /* 72 cluster name to which this md belongs */
138 	__u8  pad[256 - 136]; /* set to zero */
139 } bitmap_super_t;
140 
141 /* notes:
142  * (1) This event counter is updated before the eventcounter in the md superblock
143  *    When a bitmap is loaded, it is only accepted if this event counter is equal
144  *    to, or one greater than, the event counter in the superblock.
145  * (2) This event counter is updated when the other one is *if*and*only*if* the
146  *    array is not degraded.  As bits are not cleared when the array is degraded,
147  *    this represents the last time that any bits were cleared.
148  *    If a device is being added that has an event count with this value or
149  *    higher, it is accepted as conforming to the bitmap.
150  * (3)This is the number of sectors represented by the bitmap, and is the range that
151  *    resync happens across.  For raid1 and raid5/6 it is the size of individual
152  *    devices.  For raid10 it is the size of the array.
153  */
154 
155 #ifdef __KERNEL__
156 
157 /* the in-memory bitmap is represented by bitmap_pages */
158 struct bitmap_page {
159 	/*
160 	 * map points to the actual memory page
161 	 */
162 	char *map;
163 	/*
164 	 * in emergencies (when map cannot be alloced), hijack the map
165 	 * pointer and use it as two counters itself
166 	 */
167 	unsigned int hijacked:1;
168 	/*
169 	 * If any counter in this page is '1' or '2' - and so could be
170 	 * cleared then that page is marked as 'pending'
171 	 */
172 	unsigned int pending:1;
173 	/*
174 	 * count of dirty bits on the page
175 	 */
176 	unsigned int  count:30;
177 };
178 
179 /* the main bitmap structure - one per mddev */
180 struct bitmap {
181 
182 	struct bitmap_counts {
183 		spinlock_t lock;
184 		struct bitmap_page *bp;
185 		unsigned long pages;		/* total number of pages
186 						 * in the bitmap */
187 		unsigned long missing_pages;	/* number of pages
188 						 * not yet allocated */
189 		unsigned long chunkshift;	/* chunksize = 2^chunkshift
190 						 * (for bitops) */
191 		unsigned long chunks;		/* Total number of data
192 						 * chunks for the array */
193 	} counts;
194 
195 	struct mddev *mddev; /* the md device that the bitmap is for */
196 
197 	__u64	events_cleared;
198 	int need_sync;
199 
200 	struct bitmap_storage {
201 		struct file *file;		/* backing disk file */
202 		struct page *sb_page;		/* cached copy of the bitmap
203 						 * file superblock */
204 		struct page **filemap;		/* list of cache pages for
205 						 * the file */
206 		unsigned long *filemap_attr;	/* attributes associated
207 						 * w/ filemap pages */
208 		unsigned long file_pages;	/* number of pages in the file*/
209 		unsigned long bytes;		/* total bytes in the bitmap */
210 	} storage;
211 
212 	unsigned long flags;
213 
214 	int allclean;
215 
216 	atomic_t behind_writes;
217 	unsigned long behind_writes_used; /* highest actual value at runtime */
218 
219 	/*
220 	 * the bitmap daemon - periodically wakes up and sweeps the bitmap
221 	 * file, cleaning up bits and flushing out pages to disk as necessary
222 	 */
223 	unsigned long daemon_lastrun; /* jiffies of last run */
224 	unsigned long last_end_sync; /* when we lasted called end_sync to
225 				      * update bitmap with resync progress */
226 
227 	atomic_t pending_writes; /* pending writes to the bitmap file */
228 	wait_queue_head_t write_wait;
229 	wait_queue_head_t overflow_wait;
230 	wait_queue_head_t behind_wait;
231 
232 	struct kernfs_node *sysfs_can_clear;
233 	int cluster_slot;		/* Slot offset for clustered env */
234 };
235 
236 /* the bitmap API */
237 
238 /* these are used only by md/bitmap */
239 struct bitmap *md_bitmap_create(struct mddev *mddev, int slot);
240 int md_bitmap_load(struct mddev *mddev);
241 void md_bitmap_flush(struct mddev *mddev);
242 void md_bitmap_destroy(struct mddev *mddev);
243 
244 void md_bitmap_print_sb(struct bitmap *bitmap);
245 void md_bitmap_update_sb(struct bitmap *bitmap);
246 void md_bitmap_status(struct seq_file *seq, struct bitmap *bitmap);
247 
248 int  md_bitmap_setallbits(struct bitmap *bitmap);
249 void md_bitmap_write_all(struct bitmap *bitmap);
250 
251 void md_bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
252 
253 /* these are exported */
254 int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
255 			 unsigned long sectors, int behind);
256 void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
257 			unsigned long sectors, int success, int behind);
258 int md_bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
259 void md_bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
260 void md_bitmap_close_sync(struct bitmap *bitmap);
261 void md_bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force);
262 void md_bitmap_sync_with_cluster(struct mddev *mddev,
263 				 sector_t old_lo, sector_t old_hi,
264 				 sector_t new_lo, sector_t new_hi);
265 
266 void md_bitmap_unplug(struct bitmap *bitmap);
267 void md_bitmap_daemon_work(struct mddev *mddev);
268 
269 int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks,
270 		     int chunksize, int init);
271 struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot);
272 int md_bitmap_copy_from_slot(struct mddev *mddev, int slot,
273 			     sector_t *lo, sector_t *hi, bool clear_bits);
274 void md_bitmap_free(struct bitmap *bitmap);
275 void md_bitmap_wait_behind_writes(struct mddev *mddev);
276 #endif
277 
278 #endif
279