Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
raid1.h
Go to the documentation of this file.
1 #ifndef _RAID1_H
2 #define _RAID1_H
3 
4 struct 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 
26 struct pool_info {
27  struct mddev *mddev;
28  int raid_disks;
29 };
30 
31 struct 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 
106 struct 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 
161 extern int md_raid1_congested(struct mddev *mddev, int bits);
162 
163 #endif
Generated on Thu Jan 10 2013 13:44:19 for Linux Kernel by   doxygen 1.8.2