1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _RAID1_H
3 #define _RAID1_H
4
5 /*
6 * each barrier unit size is 64MB fow now
7 * note: it must be larger than RESYNC_DEPTH
8 */
9 #define BARRIER_UNIT_SECTOR_BITS 17
10 #define BARRIER_UNIT_SECTOR_SIZE (1<<17)
11 /*
12 * In struct r1conf, the following members are related to I/O barrier
13 * buckets,
14 * atomic_t *nr_pending;
15 * atomic_t *nr_waiting;
16 * atomic_t *nr_queued;
17 * atomic_t *barrier;
18 * Each of them points to array of atomic_t variables, each array is
19 * designed to have BARRIER_BUCKETS_NR elements and occupy a single
20 * memory page. The data width of atomic_t variables is 4 bytes, equal
21 * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
22 * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
23 * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
24 * occupies a single memory page.
25 */
26 #define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
27 #define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS)
28
29 /* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
30 * There are three safe ways to access raid1_info.rdev.
31 * 1/ when holding mddev->reconfig_mutex
32 * 2/ when resync/recovery is known to be happening - i.e. in code that is
33 * called as part of performing resync/recovery.
34 * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
35 * and if it is non-NULL, increment rdev->nr_pending before dropping the
36 * RCU lock.
37 * When .rdev is set to NULL, the nr_pending count checked again and if it has
38 * been incremented, the pointer is put back in .rdev.
39 */
40
41 struct raid1_info {
42 struct md_rdev *rdev;
43 sector_t head_position;
44
45 /* When choose the best device for a read (read_balance())
46 * we try to keep sequential reads one the same device
47 */
48 sector_t next_seq_sect;
49 sector_t seq_start;
50 };
51
52 /*
53 * memory pools need a pointer to the mddev, so they can force an unplug
54 * when memory is tight, and a count of the number of drives that the
55 * pool was allocated for, so they know how much to allocate and free.
56 * mddev->raid_disks cannot be used, as it can change while a pool is active
57 * These two datums are stored in a kmalloced struct.
58 * The 'raid_disks' here is twice the raid_disks in r1conf.
59 * This allows space for each 'real' device can have a replacement in the
60 * second half of the array.
61 */
62
63 struct pool_info {
64 struct mddev *mddev;
65 int raid_disks;
66 };
67
68 struct r1conf {
69 struct mddev *mddev;
70 struct raid1_info *mirrors; /* twice 'raid_disks' to
71 * allow for replacements.
72 */
73 int raid_disks;
74
75 spinlock_t device_lock;
76
77 /* list of 'struct r1bio' that need to be processed by raid1d,
78 * whether to retry a read, writeout a resync or recovery
79 * block, or anything else.
80 */
81 struct list_head retry_list;
82 /* A separate list of r1bio which just need raid_end_bio_io called.
83 * This mustn't happen for writes which had any errors if the superblock
84 * needs to be written.
85 */
86 struct list_head bio_end_io_list;
87
88 /* queue pending writes to be submitted on unplug */
89 struct bio_list pending_bio_list;
90 int pending_count;
91
92 /* for use when syncing mirrors:
93 * We don't allow both normal IO and resync/recovery IO at
94 * the same time - resync/recovery can only happen when there
95 * is no other IO. So when either is active, the other has to wait.
96 * See more details description in raid1.c near raise_barrier().
97 */
98 wait_queue_head_t wait_barrier;
99 spinlock_t resync_lock;
100 atomic_t nr_sync_pending;
101 atomic_t *nr_pending;
102 atomic_t *nr_waiting;
103 atomic_t *nr_queued;
104 atomic_t *barrier;
105 int array_frozen;
106
107 /* Set to 1 if a full sync is needed, (fresh device added).
108 * Cleared when a sync completes.
109 */
110 int fullsync;
111
112 /* When the same as mddev->recovery_disabled we don't allow
113 * recovery to be attempted as we expect a read error.
114 */
115 int recovery_disabled;
116
117 /* poolinfo contains information about the content of the
118 * mempools - it changes when the array grows or shrinks
119 */
120 struct pool_info *poolinfo;
121 mempool_t r1bio_pool;
122 mempool_t r1buf_pool;
123
124 struct bio_set bio_split;
125
126 /* temporary buffer to synchronous IO when attempting to repair
127 * a read error.
128 */
129 struct page *tmppage;
130
131 /* When taking over an array from a different personality, we store
132 * the new thread here until we fully activate the array.
133 */
134 struct md_thread *thread;
135
136 /* Keep track of cluster resync window to send to other
137 * nodes.
138 */
139 sector_t cluster_sync_low;
140 sector_t cluster_sync_high;
141
142 };
143
144 /*
145 * this is our 'private' RAID1 bio.
146 *
147 * it contains information about what kind of IO operations were started
148 * for this RAID1 operation, and about their status:
149 */
150
151 struct r1bio {
152 atomic_t remaining; /* 'have we finished' count,
153 * used from IRQ handlers
154 */
155 atomic_t behind_remaining; /* number of write-behind ios remaining
156 * in this BehindIO request
157 */
158 sector_t sector;
159 int sectors;
160 unsigned long state;
161 struct mddev *mddev;
162 /*
163 * original bio going to /dev/mdx
164 */
165 struct bio *master_bio;
166 /*
167 * if the IO is in READ direction, then this is where we read
168 */
169 int read_disk;
170
171 struct list_head retry_list;
172
173 /*
174 * When R1BIO_BehindIO is set, we store pages for write behind
175 * in behind_master_bio.
176 */
177 struct bio *behind_master_bio;
178
179 /*
180 * if the IO is in WRITE direction, then multiple bios are used.
181 * We choose the number when they are allocated.
182 */
183 struct bio *bios[0];
184 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
185 };
186
187 /* bits for r1bio.state */
188 enum r1bio_state {
189 R1BIO_Uptodate,
190 R1BIO_IsSync,
191 R1BIO_Degraded,
192 R1BIO_BehindIO,
193 /* Set ReadError on bios that experience a readerror so that
194 * raid1d knows what to do with them.
195 */
196 R1BIO_ReadError,
197 /* For write-behind requests, we call bi_end_io when
198 * the last non-write-behind device completes, providing
199 * any write was successful. Otherwise we call when
200 * any write-behind write succeeds, otherwise we call
201 * with failure when last write completes (and all failed).
202 * Record that bi_end_io was called with this flag...
203 */
204 R1BIO_Returned,
205 /* If a write for this request means we can clear some
206 * known-bad-block records, we set this flag
207 */
208 R1BIO_MadeGood,
209 R1BIO_WriteError,
210 R1BIO_FailFast,
211 };
212
213 static inline int sector_to_idx(sector_t sector)
214 {
215 return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
216 BARRIER_BUCKETS_NR_BITS);
217 }
218 #endif