1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _RAID1_H 3 #define _RAID1_H 4 5 /* 6 * each barrier unit size is 64MB fow now 7 * note: it must be larger than RESYNC_DEPTH 8 */ 9 #define BARRIER_UNIT_SECTOR_BITS 17 10 #define BARRIER_UNIT_SECTOR_SIZE (1<<17) 11 /* 12 * In struct r1conf, the following members are related to I/O barrier 13 * buckets, 14 * atomic_t *nr_pending; 15 * atomic_t *nr_waiting; 16 * atomic_t *nr_queued; 17 * atomic_t *barrier; 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. 25 */ 26 #define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t))) 27 #define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS) 28 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 36 * RCU lock. 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. 39 */ 40 41 struct raid1_info { 42 struct md_rdev *rdev; 43 sector_t head_position; 44 45 /* When choose the best device for a read (read_balance()) 46 * we try to keep sequential reads one the same device 47 */ 48 sector_t next_seq_sect; 49 sector_t seq_start; 50 }; 51 52 /* 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. 61 */ 62 63 struct pool_info { 64 struct mddev *mddev; 65 int raid_disks; 66 }; 67 68 struct r1conf { 69 struct mddev *mddev; 70 struct raid1_info *mirrors; /* twice 'raid_disks' to 71 * allow for replacements. 72 */ 73 int raid_disks; 74 75 spinlock_t device_lock; 76 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. 80 */ 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. 85 */ 86 struct list_head bio_end_io_list; 87 88 /* queue pending writes to be submitted on unplug */ 89 struct bio_list pending_bio_list; 90 int pending_count; 91 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(). 97 */ 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; 103 atomic_t *nr_queued; 104 atomic_t *barrier; 105 int array_frozen; 106 107 /* Set to 1 if a full sync is needed, (fresh device added). 108 * Cleared when a sync completes. 109 */ 110 int fullsync; 111 112 /* When the same as mddev->recovery_disabled we don't allow 113 * recovery to be attempted as we expect a read error. 114 */ 115 int recovery_disabled; 116 117 /* poolinfo contains information about the content of the 118 * mempools - it changes when the array grows or shrinks 119 */ 120 struct pool_info *poolinfo; 121 mempool_t r1bio_pool; 122 mempool_t r1buf_pool; 123 124 struct bio_set bio_split; 125 126 /* temporary buffer to synchronous IO when attempting to repair 127 * a read error. 128 */ 129 struct page *tmppage; 130 131 /* When taking over an array from a different personality, we store 132 * the new thread here until we fully activate the array. 133 */ 134 struct md_thread *thread; 135 136 /* Keep track of cluster resync window to send to other 137 * nodes. 138 */ 139 sector_t cluster_sync_low; 140 sector_t cluster_sync_high; 141 142 }; 143 144 /* 145 * this is our 'private' RAID1 bio. 146 * 147 * it contains information about what kind of IO operations were started 148 * for this RAID1 operation, and about their status: 149 */ 150 151 struct r1bio { 152 atomic_t remaining; /* 'have we finished' count, 153 * used from IRQ handlers 154 */ 155 atomic_t behind_remaining; /* number of write-behind ios remaining 156 * in this BehindIO request 157 */ 158 sector_t sector; 159 int sectors; 160 unsigned long state; 161 struct mddev *mddev; 162 /* 163 * original bio going to /dev/mdx 164 */ 165 struct bio *master_bio; 166 /* 167 * if the IO is in READ direction, then this is where we read 168 */ 169 int read_disk; 170 171 struct list_head retry_list; 172 173 /* 174 * When R1BIO_BehindIO is set, we store pages for write behind 175 * in behind_master_bio. 176 */ 177 struct bio *behind_master_bio; 178 179 /* 180 * if the IO is in WRITE direction, then multiple bios are used. 181 * We choose the number when they are allocated. 182 */ 183 struct bio *bios[0]; 184 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/ 185 }; 186 187 /* bits for r1bio.state */ 188 enum r1bio_state { 189 R1BIO_Uptodate, 190 R1BIO_IsSync, 191 R1BIO_Degraded, 192 R1BIO_BehindIO, 193 /* Set ReadError on bios that experience a readerror so that 194 * raid1d knows what to do with them. 195 */ 196 R1BIO_ReadError, 197 /* For write-behind requests, we call bi_end_io when 198 * the last non-write-behind device completes, providing 199 * any write was successful. Otherwise we call when 200 * any write-behind write succeeds, otherwise we call 201 * with failure when last write completes (and all failed). 202 * Record that bi_end_io was called with this flag... 203 */ 204 R1BIO_Returned, 205 /* If a write for this request means we can clear some 206 * known-bad-block records, we set this flag 207 */ 208 R1BIO_MadeGood, 209 R1BIO_WriteError, 210 R1BIO_FailFast, 211 }; 212 213 static inline int sector_to_idx(sector_t sector) 214 { 215 return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS, 216 BARRIER_BUCKETS_NR_BITS); 217 } 218 #endif 219