1 /* SPDX-License-Identifier: GPL-2.0 */
6 * each barrier unit size is 64MB fow now
7 * note: it must be larger than RESYNC_DEPTH
9 #define BARRIER_UNIT_SECTOR_BITS 17
10 #define BARRIER_UNIT_SECTOR_SIZE (1<<17)
12 * In struct r1conf, the following members are related to I/O barrier
14 * atomic_t *nr_pending;
15 * atomic_t *nr_waiting;
16 * atomic_t *nr_queued;
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.
26 #define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
27 #define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS)
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
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.
43 sector_t head_position;
45 /* When choose the best device for a read (read_balance())
46 * we try to keep sequential reads one the same device
48 sector_t next_seq_sect;
53 * memory pools need a pointer to the mddev, so they can force an unplug
54 * when memory is tight, and a count of the number of drives that the
55 * pool was allocated for, so they know how much to allocate and free.
56 * mddev->raid_disks cannot be used, as it can change while a pool is active
57 * These two datums are stored in a kmalloced struct.
58 * The 'raid_disks' here is twice the raid_disks in r1conf.
59 * This allows space for each 'real' device can have a replacement in the
60 * second half of the array.
70 struct raid1_info *mirrors; /* twice 'raid_disks' to
71 * allow for replacements.
75 spinlock_t device_lock;
77 /* list of 'struct r1bio' that need to be processed by raid1d,
78 * whether to retry a read, writeout a resync or recovery
79 * block, or anything else.
81 struct list_head retry_list;
82 /* A separate list of r1bio which just need raid_end_bio_io called.
83 * This mustn't happen for writes which had any errors if the superblock
84 * needs to be written.
86 struct list_head bio_end_io_list;
88 /* queue pending writes to be submitted on unplug */
89 struct bio_list pending_bio_list;
92 /* for use when syncing mirrors:
93 * We don't allow both normal IO and resync/recovery IO at
94 * the same time - resync/recovery can only happen when there
95 * is no other IO. So when either is active, the other has to wait.
96 * See more details description in raid1.c near raise_barrier().
98 wait_queue_head_t wait_barrier;
99 spinlock_t resync_lock;
100 atomic_t nr_sync_pending;
101 atomic_t *nr_pending;
102 atomic_t *nr_waiting;
107 /* Set to 1 if a full sync is needed, (fresh device added).
108 * Cleared when a sync completes.
112 /* When the same as mddev->recovery_disabled we don't allow
113 * recovery to be attempted as we expect a read error.
115 int recovery_disabled;
117 /* poolinfo contains information about the content of the
118 * mempools - it changes when the array grows or shrinks
120 struct pool_info *poolinfo;
121 mempool_t r1bio_pool;
122 mempool_t r1buf_pool;
124 struct bio_set bio_split;
126 /* temporary buffer to synchronous IO when attempting to repair
129 struct page *tmppage;
131 /* When taking over an array from a different personality, we store
132 * the new thread here until we fully activate the array.
134 struct md_thread *thread;
136 /* Keep track of cluster resync window to send to other
139 sector_t cluster_sync_low;
140 sector_t cluster_sync_high;
145 * this is our 'private' RAID1 bio.
147 * it contains information about what kind of IO operations were started
148 * for this RAID1 operation, and about their status:
152 atomic_t remaining; /* 'have we finished' count,
153 * used from IRQ handlers
155 atomic_t behind_remaining; /* number of write-behind ios remaining
156 * in this BehindIO request
161 unsigned long start_time;
164 * original bio going to /dev/mdx
166 struct bio *master_bio;
168 * if the IO is in READ direction, then this is where we read
172 struct list_head retry_list;
175 * When R1BIO_BehindIO is set, we store pages for write behind
176 * in behind_master_bio.
178 struct bio *behind_master_bio;
181 * if the IO is in WRITE direction, then multiple bios are used.
182 * We choose the number when they are allocated.
185 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
188 /* bits for r1bio.state */
194 /* Set ReadError on bios that experience a readerror so that
195 * raid1d knows what to do with them.
198 /* For write-behind requests, we call bi_end_io when
199 * the last non-write-behind device completes, providing
200 * any write was successful. Otherwise we call when
201 * any write-behind write succeeds, otherwise we call
202 * with failure when last write completes (and all failed).
203 * Record that bi_end_io was called with this flag...
206 /* If a write for this request means we can clear some
207 * known-bad-block records, we set this flag
214 static inline int sector_to_idx(sector_t sector)
216 return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
217 BARRIER_BUCKETS_NR_BITS);