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 struct r1conf { 53 struct mddev *mddev; 54 struct raid1_info *mirrors; /* twice 'raid_disks' to 55 * allow for replacements. 56 */ 57 int raid_disks; 58 int nonrot_disks; 59 60 spinlock_t device_lock; 61 62 /* list of 'struct r1bio' that need to be processed by raid1d, 63 * whether to retry a read, writeout a resync or recovery 64 * block, or anything else. 65 */ 66 struct list_head retry_list; 67 /* A separate list of r1bio which just need raid_end_bio_io called. 68 * This mustn't happen for writes which had any errors if the superblock 69 * needs to be written. 70 */ 71 struct list_head bio_end_io_list; 72 73 /* queue pending writes to be submitted on unplug */ 74 struct bio_list pending_bio_list; 75 76 /* for use when syncing mirrors: 77 * We don't allow both normal IO and resync/recovery IO at 78 * the same time - resync/recovery can only happen when there 79 * is no other IO. So when either is active, the other has to wait. 80 * See more details description in raid1.c near raise_barrier(). 81 */ 82 wait_queue_head_t wait_barrier; 83 spinlock_t resync_lock; 84 atomic_t nr_sync_pending; 85 atomic_t *nr_pending; 86 atomic_t *nr_waiting; 87 atomic_t *nr_queued; 88 atomic_t *barrier; 89 int array_frozen; 90 91 /* Set to 1 if a full sync is needed, (fresh device added). 92 * Cleared when a sync completes. 93 */ 94 int fullsync; 95 96 mempool_t *r1bio_pool; 97 mempool_t r1buf_pool; 98 99 struct bio_set bio_split; 100 101 /* temporary buffer to synchronous IO when attempting to repair 102 * a read error. 103 */ 104 struct page *tmppage; 105 106 /* When taking over an array from a different personality, we store 107 * the new thread here until we fully activate the array. 108 */ 109 struct md_thread __rcu *thread; 110 111 /* Keep track of cluster resync window to send to other 112 * nodes. 113 */ 114 sector_t cluster_sync_low; 115 sector_t cluster_sync_high; 116 117 }; 118 119 /* 120 * this is our 'private' RAID1 bio. 121 * 122 * it contains information about what kind of IO operations were started 123 * for this RAID1 operation, and about their status: 124 */ 125 126 struct r1bio { 127 atomic_t remaining; /* 'have we finished' count, 128 * used from IRQ handlers 129 */ 130 atomic_t behind_remaining; /* number of write-behind ios remaining 131 * in this BehindIO request 132 */ 133 sector_t sector; 134 int sectors; 135 unsigned long state; 136 struct mddev *mddev; 137 /* 138 * original bio going to /dev/mdx 139 */ 140 struct bio *master_bio; 141 /* 142 * if the IO is in READ direction, then this is where we read 143 */ 144 int read_disk; 145 146 struct list_head retry_list; 147 148 /* 149 * When R1BIO_BehindIO is set, we store pages for write behind 150 * in behind_master_bio. 151 */ 152 struct bio *behind_master_bio; 153 154 /* 155 * if the IO is in WRITE direction, then multiple bios are used. 156 * We choose the number when they are allocated. 157 */ 158 struct bio *bios[]; 159 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/ 160 }; 161 162 /* bits for r1bio.state */ 163 enum r1bio_state { 164 R1BIO_Uptodate, 165 R1BIO_IsSync, 166 R1BIO_BehindIO, 167 /* Set ReadError on bios that experience a readerror so that 168 * raid1d knows what to do with them. 169 */ 170 R1BIO_ReadError, 171 /* For write-behind requests, we call bi_end_io when 172 * the last non-write-behind device completes, providing 173 * any write was successful. Otherwise we call when 174 * any write-behind write succeeds, otherwise we call 175 * with failure when last write completes (and all failed). 176 * 177 * And for bio_split errors, record that bi_end_io was called 178 * with this flag... 179 */ 180 R1BIO_Returned, 181 /* If a write for this request means we can clear some 182 * known-bad-block records, we set this flag 183 */ 184 R1BIO_MadeGood, 185 R1BIO_WriteError, 186 R1BIO_FailFast, 187 }; 188 189 static inline int sector_to_idx(sector_t sector) 190 { 191 return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS, 192 BARRIER_BUCKETS_NR_BITS); 193 } 194 #endif 195