Root/drivers/md/raid1.h

1#ifndef _RAID1_H
2#define _RAID1_H
3
4struct raid1_info {
5    struct md_rdev *rdev;
6    sector_t head_position;
7
8    /* When choose the best device for a read (read_balance())
9     * we try to keep sequential reads one the same device
10     */
11    sector_t next_seq_sect;
12    sector_t seq_start;
13};
14
15/*
16 * memory pools need a pointer to the mddev, so they can force an unplug
17 * when memory is tight, and a count of the number of drives that the
18 * pool was allocated for, so they know how much to allocate and free.
19 * mddev->raid_disks cannot be used, as it can change while a pool is active
20 * These two datums are stored in a kmalloced struct.
21 * The 'raid_disks' here is twice the raid_disks in r1conf.
22 * This allows space for each 'real' device can have a replacement in the
23 * second half of the array.
24 */
25
26struct pool_info {
27    struct mddev *mddev;
28    int raid_disks;
29};
30
31struct r1conf {
32    struct mddev *mddev;
33    struct raid1_info *mirrors; /* twice 'raid_disks' to
34                         * allow for replacements.
35                         */
36    int raid_disks;
37
38    /* During resync, read_balancing is only allowed on the part
39     * of the array that has been resynced. 'next_resync' tells us
40     * where that is.
41     */
42    sector_t next_resync;
43
44    spinlock_t device_lock;
45
46    /* list of 'struct r1bio' that need to be processed by raid1d,
47     * whether to retry a read, writeout a resync or recovery
48     * block, or anything else.
49     */
50    struct list_head retry_list;
51
52    /* queue pending writes to be submitted on unplug */
53    struct bio_list pending_bio_list;
54    int pending_count;
55
56    /* for use when syncing mirrors:
57     * We don't allow both normal IO and resync/recovery IO at
58     * the same time - resync/recovery can only happen when there
59     * is no other IO. So when either is active, the other has to wait.
60     * See more details description in raid1.c near raise_barrier().
61     */
62    wait_queue_head_t wait_barrier;
63    spinlock_t resync_lock;
64    int nr_pending;
65    int nr_waiting;
66    int nr_queued;
67    int barrier;
68
69    /* Set to 1 if a full sync is needed, (fresh device added).
70     * Cleared when a sync completes.
71     */
72    int fullsync;
73
74    /* When the same as mddev->recovery_disabled we don't allow
75     * recovery to be attempted as we expect a read error.
76     */
77    int recovery_disabled;
78
79
80    /* poolinfo contains information about the content of the
81     * mempools - it changes when the array grows or shrinks
82     */
83    struct pool_info *poolinfo;
84    mempool_t *r1bio_pool;
85    mempool_t *r1buf_pool;
86
87    /* temporary buffer to synchronous IO when attempting to repair
88     * a read error.
89     */
90    struct page *tmppage;
91
92
93    /* When taking over an array from a different personality, we store
94     * the new thread here until we fully activate the array.
95     */
96    struct md_thread *thread;
97};
98
99/*
100 * this is our 'private' RAID1 bio.
101 *
102 * it contains information about what kind of IO operations were started
103 * for this RAID1 operation, and about their status:
104 */
105
106struct r1bio {
107    atomic_t remaining; /* 'have we finished' count,
108                        * used from IRQ handlers
109                        */
110    atomic_t behind_remaining; /* number of write-behind ios remaining
111                         * in this BehindIO request
112                         */
113    sector_t sector;
114    int sectors;
115    unsigned long state;
116    struct mddev *mddev;
117    /*
118     * original bio going to /dev/mdx
119     */
120    struct bio *master_bio;
121    /*
122     * if the IO is in READ direction, then this is where we read
123     */
124    int read_disk;
125
126    struct list_head retry_list;
127    /* Next two are only valid when R1BIO_BehindIO is set */
128    struct bio_vec *behind_bvecs;
129    int behind_page_count;
130    /*
131     * if the IO is in WRITE direction, then multiple bios are used.
132     * We choose the number when they are allocated.
133     */
134    struct bio *bios[0];
135    /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
136};
137
138/* bits for r1bio.state */
139#define R1BIO_Uptodate 0
140#define R1BIO_IsSync 1
141#define R1BIO_Degraded 2
142#define R1BIO_BehindIO 3
143/* Set ReadError on bios that experience a readerror so that
144 * raid1d knows what to do with them.
145 */
146#define R1BIO_ReadError 4
147/* For write-behind requests, we call bi_end_io when
148 * the last non-write-behind device completes, providing
149 * any write was successful. Otherwise we call when
150 * any write-behind write succeeds, otherwise we call
151 * with failure when last write completes (and all failed).
152 * Record that bi_end_io was called with this flag...
153 */
154#define R1BIO_Returned 6
155/* If a write for this request means we can clear some
156 * known-bad-block records, we set this flag
157 */
158#define R1BIO_MadeGood 7
159#define R1BIO_WriteError 8
160
161extern int md_raid1_congested(struct mddev *mddev, int bits);
162
163#endif
164

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