/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _RAID1_H #define _RAID1_H /* * each barrier unit size is 64MB fow now * note: it must be larger than RESYNC_DEPTH */ #define BARRIER_UNIT_SECTOR_BITS 17 #define BARRIER_UNIT_SECTOR_SIZE (1<<17) /* * In struct r1conf, the following members are related to I/O barrier * buckets, * atomic_t *nr_pending; * atomic_t *nr_waiting; * atomic_t *nr_queued; * atomic_t *barrier; * Each of them points to array of atomic_t variables, each array is * designed to have BARRIER_BUCKETS_NR elements and occupy a single * memory page. The data width of atomic_t variables is 4 bytes, equal * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly * occupies a single memory page. */ #define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t))) #define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS) /* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk. * There are three safe ways to access raid1_info.rdev. * 1/ when holding mddev->reconfig_mutex * 2/ when resync/recovery is known to be happening - i.e. in code that is * called as part of performing resync/recovery. * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer * and if it is non-NULL, increment rdev->nr_pending before dropping the * RCU lock. * When .rdev is set to NULL, the nr_pending count checked again and if it has * been incremented, the pointer is put back in .rdev. */ struct raid1_info { struct md_rdev *rdev; sector_t head_position; /* When choose the best device for a read (read_balance()) * we try to keep sequential reads one the same device */ sector_t next_seq_sect; sector_t seq_start; }; struct r1conf { struct mddev *mddev; struct raid1_info *mirrors; /* twice 'raid_disks' to * allow for replacements. */ int raid_disks; int nonrot_disks; spinlock_t device_lock; /* list of 'struct r1bio' that need to be processed by raid1d, * whether to retry a read, writeout a resync or recovery * block, or anything else. */ struct list_head retry_list; /* A separate list of r1bio which just need raid_end_bio_io called. * This mustn't happen for writes which had any errors if the superblock * needs to be written. */ struct list_head bio_end_io_list; /* queue pending writes to be submitted on unplug */ struct bio_list pending_bio_list; /* for use when syncing mirrors: * We don't allow both normal IO and resync/recovery IO at * the same time - resync/recovery can only happen when there * is no other IO. So when either is active, the other has to wait. * See more details description in raid1.c near raise_barrier(). */ wait_queue_head_t wait_barrier; spinlock_t resync_lock; atomic_t nr_sync_pending; atomic_t *nr_pending; atomic_t *nr_waiting; atomic_t *nr_queued; atomic_t *barrier; int array_frozen; /* Set to 1 if a full sync is needed, (fresh device added). * Cleared when a sync completes. */ int fullsync; mempool_t *r1bio_pool; mempool_t r1buf_pool; struct bio_set bio_split; /* temporary buffer to synchronous IO when attempting to repair * a read error. */ struct page *tmppage; /* When taking over an array from a different personality, we store * the new thread here until we fully activate the array. */ struct md_thread __rcu *thread; /* Keep track of cluster resync window to send to other * nodes. */ sector_t cluster_sync_low; sector_t cluster_sync_high; }; /* * this is our 'private' RAID1 bio. * * it contains information about what kind of IO operations were started * for this RAID1 operation, and about their status: */ struct r1bio { atomic_t remaining; /* 'have we finished' count, * used from IRQ handlers */ atomic_t behind_remaining; /* number of write-behind ios remaining * in this BehindIO request */ sector_t sector; int sectors; unsigned long state; struct mddev *mddev; /* * original bio going to /dev/mdx */ struct bio *master_bio; /* * if the IO is in READ direction, then this is where we read */ int read_disk; struct list_head retry_list; /* * When R1BIO_BehindIO is set, we store pages for write behind * in behind_master_bio. */ struct bio *behind_master_bio; /* * if the IO is in WRITE direction, then multiple bios are used. * We choose the number when they are allocated. */ struct bio *bios[]; /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/ }; /* bits for r1bio.state */ enum r1bio_state { R1BIO_Uptodate, R1BIO_IsSync, R1BIO_BehindIO, /* Set ReadError on bios that experience a readerror so that * raid1d knows what to do with them. */ R1BIO_ReadError, /* For write-behind requests, we call bi_end_io when * the last non-write-behind device completes, providing * any write was successful. Otherwise we call when * any write-behind write succeeds, otherwise we call * with failure when last write completes (and all failed). * * And for bio_split errors, record that bi_end_io was called * with this flag... */ R1BIO_Returned, /* If a write for this request means we can clear some * known-bad-block records, we set this flag */ R1BIO_MadeGood, R1BIO_WriteError, R1BIO_FailFast, }; static inline int sector_to_idx(sector_t sector) { return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS, BARRIER_BUCKETS_NR_BITS); } #endif
