diff options
Diffstat (limited to 'drivers/md/raid1.h')
| -rw-r--r-- | drivers/md/raid1.h | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h new file mode 100644 index 000000000..b7eb09e8c --- /dev/null +++ b/drivers/md/raid1.h @@ -0,0 +1,218 @@ +/* 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; +}; + +/* + * memory pools need a pointer to the mddev, so they can force an unplug + * when memory is tight, and a count of the number of drives that the + * pool was allocated for, so they know how much to allocate and free. + * mddev->raid_disks cannot be used, as it can change while a pool is active + * These two datums are stored in a kmalloced struct. + * The 'raid_disks' here is twice the raid_disks in r1conf. + * This allows space for each 'real' device can have a replacement in the + * second half of the array. + */ + +struct pool_info { + struct mddev *mddev; + int raid_disks; +}; + +struct r1conf { + struct mddev *mddev; + struct raid1_info *mirrors; /* twice 'raid_disks' to + * allow for replacements. + */ + int raid_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; + int pending_count; + + /* 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; + + /* When the same as mddev->recovery_disabled we don't allow + * recovery to be attempted as we expect a read error. + */ + int recovery_disabled; + + /* poolinfo contains information about the content of the + * mempools - it changes when the array grows or shrinks + */ + struct pool_info *poolinfo; + 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 *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_Degraded, + 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). + * 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 |