6 sector_t head_position;
8 /* When choose the best device for a read (read_balance())
9 * we try to keep sequential reads one the same device
11 sector_t next_seq_sect;
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.
33 struct raid1_info *mirrors; /* twice 'raid_disks' to
34 * allow for replacements.
38 /* During resync, read_balancing is only allowed on the part
39 * of the array that has been resynced. 'next_resync' tells us
44 spinlock_t device_lock;
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.
50 struct list_head retry_list;
52 /* queue pending writes to be submitted on unplug */
53 struct bio_list pending_bio_list;
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().
62 wait_queue_head_t wait_barrier;
63 spinlock_t resync_lock;
70 /* Set to 1 if a full sync is needed, (fresh device added).
71 * Cleared when a sync completes.
75 /* When the same as mddev->recovery_disabled we don't allow
76 * recovery to be attempted as we expect a read error.
78 int recovery_disabled;
81 /* poolinfo contains information about the content of the
82 * mempools - it changes when the array grows or shrinks
84 struct pool_info *poolinfo;
85 mempool_t *r1bio_pool;
86 mempool_t *r1buf_pool;
88 /* temporary buffer to synchronous IO when attempting to repair
94 /* When taking over an array from a different personality, we store
95 * the new thread here until we fully activate the array.
97 struct md_thread *thread;
101 * this is our 'private' RAID1 bio.
103 * it contains information about what kind of IO operations were started
104 * for this RAID1 operation, and about their status:
108 atomic_t remaining; /* 'have we finished' count,
109 * used from IRQ handlers
111 atomic_t behind_remaining; /* number of write-behind ios remaining
112 * in this BehindIO request
119 * original bio going to /dev/mdx
121 struct bio *master_bio;
123 * if the IO is in READ direction, then this is where we read
127 struct list_head retry_list;
128 /* Next two are only valid when R1BIO_BehindIO is set */
129 struct bio_vec *behind_bvecs;
130 int behind_page_count;
132 * if the IO is in WRITE direction, then multiple bios are used.
133 * We choose the number when they are allocated.
136 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
139 /* bits for r1bio.state */
140 #define R1BIO_Uptodate 0
141 #define R1BIO_IsSync 1
142 #define R1BIO_Degraded 2
143 #define R1BIO_BehindIO 3
144 /* Set ReadError on bios that experience a readerror so that
145 * raid1d knows what to do with them.
147 #define R1BIO_ReadError 4
148 /* For write-behind requests, we call bi_end_io when
149 * the last non-write-behind device completes, providing
150 * any write was successful. Otherwise we call when
151 * any write-behind write succeeds, otherwise we call
152 * with failure when last write completes (and all failed).
153 * Record that bi_end_io was called with this flag...
155 #define R1BIO_Returned 6
156 /* If a write for this request means we can clear some
157 * known-bad-block records, we set this flag
159 #define R1BIO_MadeGood 7
160 #define R1BIO_WriteError 8
162 extern int md_raid1_congested(struct mddev *mddev, int bits);