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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _RAID1_H3#define _RAID1_H4 5/*6 * each barrier unit size is 64MB fow now7 * note: it must be larger than RESYNC_DEPTH8 */9#define BARRIER_UNIT_SECTOR_BITS 1710#define BARRIER_UNIT_SECTOR_SIZE (1<<17)11/*12 * In struct r1conf, the following members are related to I/O barrier13 * 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 is19 * designed to have BARRIER_BUCKETS_NR elements and occupy a single20 * memory page. The data width of atomic_t variables is 4 bytes, equal21 * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined22 * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of23 * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly24 * 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_mutex32 * 2/ when resync/recovery is known to be happening - i.e. in code that is33 * called as part of performing resync/recovery.34 * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer35 * and if it is non-NULL, increment rdev->nr_pending before dropping the36 * RCU lock.37 * When .rdev is set to NULL, the nr_pending count checked again and if it has38 * been incremented, the pointer is put back in .rdev.39 */40 41struct 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 device47 */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 unplug54 * when memory is tight, and a count of the number of drives that the55 * 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 active57 * 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 the60 * second half of the array.61 */62 63struct pool_info {64 struct mddev *mddev;65 int raid_disks;66};67 68struct r1conf {69 struct mddev *mddev;70 struct raid1_info *mirrors; /* twice 'raid_disks' to71 * allow for replacements.72 */73 int raid_disks;74 int nonrot_disks;75 76 spinlock_t device_lock;77 78 /* list of 'struct r1bio' that need to be processed by raid1d,79 * whether to retry a read, writeout a resync or recovery80 * block, or anything else.81 */82 struct list_head retry_list;83 /* A separate list of r1bio which just need raid_end_bio_io called.84 * This mustn't happen for writes which had any errors if the superblock85 * needs to be written.86 */87 struct list_head bio_end_io_list;88 89 /* queue pending writes to be submitted on unplug */90 struct bio_list pending_bio_list;91 92 /* for use when syncing mirrors:93 * We don't allow both normal IO and resync/recovery IO at94 * the same time - resync/recovery can only happen when there95 * 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 allow113 * recovery to be attempted as we expect a read error.114 */115 int recovery_disabled;116 117 /* poolinfo contains information about the content of the118 * mempools - it changes when the array grows or shrinks119 */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 repair127 * a read error.128 */129 struct page *tmppage;130 131 /* When taking over an array from a different personality, we store132 * the new thread here until we fully activate the array.133 */134 struct md_thread __rcu *thread;135 136 /* Keep track of cluster resync window to send to other137 * 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 started148 * for this RAID1 operation, and about their status:149 */150 151struct r1bio {152 atomic_t remaining; /* 'have we finished' count,153 * used from IRQ handlers154 */155 atomic_t behind_remaining; /* number of write-behind ios remaining156 * in this BehindIO request157 */158 sector_t sector;159 int sectors;160 unsigned long state;161 struct mddev *mddev;162 /*163 * original bio going to /dev/mdx164 */165 struct bio *master_bio;166 /*167 * if the IO is in READ direction, then this is where we read168 */169 int read_disk;170 171 struct list_head retry_list;172 173 /*174 * When R1BIO_BehindIO is set, we store pages for write behind175 * 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[];184 /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/185};186 187/* bits for r1bio.state */188enum r1bio_state {189 R1BIO_Uptodate,190 R1BIO_IsSync,191 R1BIO_Degraded,192 R1BIO_BehindIO,193/* Set ReadError on bios that experience a readerror so that194 * raid1d knows what to do with them.195 */196 R1BIO_ReadError,197/* For write-behind requests, we call bi_end_io when198 * the last non-write-behind device completes, providing199 * any write was successful. Otherwise we call when200 * any write-behind write succeeds, otherwise we call201 * 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 some206 * known-bad-block records, we set this flag207 */208 R1BIO_MadeGood,209 R1BIO_WriteError,210 R1BIO_FailFast,211};212 213static 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#endif219