1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _RAID1_H
#define _RAID1_H
/*
* each barrier unit size is 64MB fow now
* note: it must be larger than RESYNC_DEPTH
*/
#define BARRIER_UNIT_SECTOR_BITS 17
#define BARRIER_UNIT_SECTOR_SIZE (1<<17)
/*
* In struct r1conf, the following members are related to I/O barrier
* buckets,
* atomic_t *nr_pending;
* atomic_t *nr_waiting;
* atomic_t *nr_queued;
* atomic_t *barrier;
* Each of them points to array of atomic_t variables, each array is
* designed to have BARRIER_BUCKETS_NR elements and occupy a single
* memory page. The data width of atomic_t variables is 4 bytes, equal
* to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
* as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
* atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
* occupies a single memory page.
*/
#define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
#define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS)
/* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
* There are three safe ways to access raid1_info.rdev.
* 1/ when holding mddev->reconfig_mutex
* 2/ when resync/recovery is known to be happening - i.e. in code that is
* called as part of performing resync/recovery.
* 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
* and if it is non-NULL, increment rdev->nr_pending before dropping the
* RCU lock.
* When .rdev is set to NULL, the nr_pending count checked again and if it has
* been incremented, the pointer is put back in .rdev.
*/
struct raid1_info {
struct md_rdev *rdev;
sector_t head_position;
/* When choose the best device for a read (read_balance())
* we try to keep sequential reads one the same device
*/
sector_t next_seq_sect;
sector_t seq_start;
};
/*
* memory pools need a pointer to the mddev, so they can force an unplug
* when memory is tight, and a count of the number of drives that the
* pool was allocated for, so they know how much to allocate and free.
* mddev->raid_disks cannot be used, as it can change while a pool is active
* These two datums are stored in a kmalloced struct.
* The 'raid_disks' here is twice the raid_disks in r1conf.
* This allows space for each 'real' device can have a replacement in the
* second half of the array.
*/
struct pool_info {
struct mddev *mddev;
int raid_disks;
};
struct r1conf {
struct mddev *mddev;
struct raid1_info *mirrors; /* twice 'raid_disks' to
* allow for replacements.
*/
int raid_disks;
spinlock_t device_lock;
/* list of 'struct r1bio' that need to be processed by raid1d,
* whether to retry a read, writeout a resync or recovery
* block, or anything else.
*/
struct list_head retry_list;
/* A separate list of r1bio which just need raid_end_bio_io called.
* This mustn't happen for writes which had any errors if the superblock
* needs to be written.
*/
struct list_head bio_end_io_list;
/* queue pending writes to be submitted on unplug */
struct bio_list pending_bio_list;
int pending_count;
/* for use when syncing mirrors:
* We don't allow both normal IO and resync/recovery IO at
* the same time - resync/recovery can only happen when there
* is no other IO. So when either is active, the other has to wait.
* See more details description in raid1.c near raise_barrier().
*/
wait_queue_head_t wait_barrier;
spinlock_t resync_lock;
atomic_t nr_sync_pending;
atomic_t *nr_pending;
atomic_t *nr_waiting;
atomic_t *nr_queued;
atomic_t *barrier;
int array_frozen;
/* Set to 1 if a full sync is needed, (fresh device added).
* Cleared when a sync completes.
*/
int fullsync;
/* When the same as mddev->recovery_disabled we don't allow
* recovery to be attempted as we expect a read error.
*/
int recovery_disabled;
/* poolinfo contains information about the content of the
* mempools - it changes when the array grows or shrinks
*/
struct pool_info *poolinfo;
mempool_t r1bio_pool;
mempool_t r1buf_pool;
struct bio_set bio_split;
/* temporary buffer to synchronous IO when attempting to repair
* a read error.
*/
struct page *tmppage;
/* When taking over an array from a different personality, we store
* the new thread here until we fully activate the array.
*/
struct md_thread *thread;
/* Keep track of cluster resync window to send to other
* nodes.
*/
sector_t cluster_sync_low;
sector_t cluster_sync_high;
};
/*
* this is our 'private' RAID1 bio.
*
* it contains information about what kind of IO operations were started
* for this RAID1 operation, and about their status:
*/
struct r1bio {
atomic_t remaining; /* 'have we finished' count,
* used from IRQ handlers
*/
atomic_t behind_remaining; /* number of write-behind ios remaining
* in this BehindIO request
*/
sector_t sector;
int sectors;
unsigned long state;
unsigned long start_time;
struct mddev *mddev;
/*
* original bio going to /dev/mdx
*/
struct bio *master_bio;
/*
* if the IO is in READ direction, then this is where we read
*/
int read_disk;
struct list_head retry_list;
/*
* When R1BIO_BehindIO is set, we store pages for write behind
* in behind_master_bio.
*/
struct bio *behind_master_bio;
/*
* if the IO is in WRITE direction, then multiple bios are used.
* We choose the number when they are allocated.
*/
struct bio *bios[];
/* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
};
/* bits for r1bio.state */
enum r1bio_state {
R1BIO_Uptodate,
R1BIO_IsSync,
R1BIO_Degraded,
R1BIO_BehindIO,
/* Set ReadError on bios that experience a readerror so that
* raid1d knows what to do with them.
*/
R1BIO_ReadError,
/* For write-behind requests, we call bi_end_io when
* the last non-write-behind device completes, providing
* any write was successful. Otherwise we call when
* any write-behind write succeeds, otherwise we call
* with failure when last write completes (and all failed).
* Record that bi_end_io was called with this flag...
*/
R1BIO_Returned,
/* If a write for this request means we can clear some
* known-bad-block records, we set this flag
*/
R1BIO_MadeGood,
R1BIO_WriteError,
R1BIO_FailFast,
};
static inline int sector_to_idx(sector_t sector)
{
return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
BARRIER_BUCKETS_NR_BITS);
}
#endif
|
