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 struct r1conf {
53 struct mddev *mddev;
54 struct raid1_info *mirrors; /* twice 'raid_disks' to
55 * allow for replacements.
56 */
57 int raid_disks;
58 int nonrot_disks;
59
60 spinlock_t device_lock;
61
62 /* list of 'struct r1bio' that need to be processed by raid1d,
63 * whether to retry a read, writeout a resync or recovery
64 * block, or anything else.
65 */
66 struct list_head retry_list;
67 /* A separate list of r1bio which just need raid_end_bio_io called.
68 * This mustn't happen for writes which had any errors if the superblock
69 * needs to be written.
70 */
71 struct list_head bio_end_io_list;
72
73 /* queue pending writes to be submitted on unplug */
74 struct bio_list pending_bio_list;
75
76 /* for use when syncing mirrors:
77 * We don't allow both normal IO and resync/recovery IO at
78 * the same time - resync/recovery can only happen when there
79 * is no other IO. So when either is active, the other has to wait.
80 * See more details description in raid1.c near raise_barrier().
81 */
82 wait_queue_head_t wait_barrier;
83 spinlock_t resync_lock;
84 atomic_t nr_sync_pending;
85 atomic_t *nr_pending;
86 atomic_t *nr_waiting;
87 atomic_t *nr_queued;
88 atomic_t *barrier;
89 int array_frozen;
90
91 /* Set to 1 if a full sync is needed, (fresh device added).
92 * Cleared when a sync completes.
93 */
94 int fullsync;
95
96 /* When the same as mddev->recovery_disabled we don't allow
97 * recovery to be attempted as we expect a read error.
98 */
99 int recovery_disabled;
100
101 mempool_t *r1bio_pool;
102 mempool_t r1buf_pool;
103
104 struct bio_set bio_split;
105
106 /* temporary buffer to synchronous IO when attempting to repair
107 * a read error.
108 */
109 struct page *tmppage;
110
111 /* When taking over an array from a different personality, we store
112 * the new thread here until we fully activate the array.
113 */
114 struct md_thread __rcu *thread;
115
116 /* Keep track of cluster resync window to send to other
117 * nodes.
118 */
119 sector_t cluster_sync_low;
120 sector_t cluster_sync_high;
121
122 };
123
124 /*
125 * this is our 'private' RAID1 bio.
126 *
127 * it contains information about what kind of IO operations were started
128 * for this RAID1 operation, and about their status:
129 */
130
131 struct r1bio {
132 atomic_t remaining; /* 'have we finished' count,
133 * used from IRQ handlers
134 */
135 atomic_t behind_remaining; /* number of write-behind ios remaining
136 * in this BehindIO request
137 */
138 sector_t sector;
139 int sectors;
140 unsigned long state;
141 struct mddev *mddev;
142 /*
143 * original bio going to /dev/mdx
144 */
145 struct bio *master_bio;
146 /*
147 * if the IO is in READ direction, then this is where we read
148 */
149 int read_disk;
150
151 struct list_head retry_list;
152
153 /*
154 * When R1BIO_BehindIO is set, we store pages for write behind
155 * in behind_master_bio.
156 */
157 struct bio *behind_master_bio;
158
159 /*
160 * if the IO is in WRITE direction, then multiple bios are used.
161 * We choose the number when they are allocated.
162 */
163 struct bio *bios[];
164 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
165 };
166
167 /* bits for r1bio.state */
168 enum r1bio_state {
169 R1BIO_Uptodate,
170 R1BIO_IsSync,
171 R1BIO_BehindIO,
172 /* Set ReadError on bios that experience a readerror so that
173 * raid1d knows what to do with them.
174 */
175 R1BIO_ReadError,
176 /* For write-behind requests, we call bi_end_io when
177 * the last non-write-behind device completes, providing
178 * any write was successful. Otherwise we call when
179 * any write-behind write succeeds, otherwise we call
180 * with failure when last write completes (and all failed).
181 * Record that bi_end_io was called with this flag...
182 */
183 R1BIO_Returned,
184 /* If a write for this request means we can clear some
185 * known-bad-block records, we set this flag
186 */
187 R1BIO_MadeGood,
188 R1BIO_WriteError,
189 R1BIO_FailFast,
190 };
191
sector_to_idx(sector_t sector)192 static inline int sector_to_idx(sector_t sector)
193 {
194 return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
195 BARRIER_BUCKETS_NR_BITS);
196 }
197 #endif
198