219 lines
6.3 KiB
C
Executable file
219 lines
6.3 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _RAID1_H
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#define _RAID1_H
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/*
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* each barrier unit size is 64MB fow now
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* note: it must be larger than RESYNC_DEPTH
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*/
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#define BARRIER_UNIT_SECTOR_BITS 17
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#define BARRIER_UNIT_SECTOR_SIZE (1<<17)
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/*
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* In struct r1conf, the following members are related to I/O barrier
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* buckets,
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* atomic_t *nr_pending;
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* atomic_t *nr_waiting;
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* atomic_t *nr_queued;
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* atomic_t *barrier;
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* Each of them points to array of atomic_t variables, each array is
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* designed to have BARRIER_BUCKETS_NR elements and occupy a single
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* memory page. The data width of atomic_t variables is 4 bytes, equal
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* to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
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* as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
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* atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
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* occupies a single memory page.
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*/
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#define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
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#define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS)
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/* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
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* There are three safe ways to access raid1_info.rdev.
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* 1/ when holding mddev->reconfig_mutex
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* 2/ when resync/recovery is known to be happening - i.e. in code that is
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* called as part of performing resync/recovery.
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* 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
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* and if it is non-NULL, increment rdev->nr_pending before dropping the
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* RCU lock.
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* When .rdev is set to NULL, the nr_pending count checked again and if it has
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* been incremented, the pointer is put back in .rdev.
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*/
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struct raid1_info {
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struct md_rdev *rdev;
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sector_t head_position;
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/* When choose the best device for a read (read_balance())
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* we try to keep sequential reads one the same device
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*/
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sector_t next_seq_sect;
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sector_t seq_start;
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};
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/*
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* memory pools need a pointer to the mddev, so they can force an unplug
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* when memory is tight, and a count of the number of drives that the
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* pool was allocated for, so they know how much to allocate and free.
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* mddev->raid_disks cannot be used, as it can change while a pool is active
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* These two datums are stored in a kmalloced struct.
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* The 'raid_disks' here is twice the raid_disks in r1conf.
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* This allows space for each 'real' device can have a replacement in the
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* second half of the array.
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*/
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struct pool_info {
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struct mddev *mddev;
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int raid_disks;
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};
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struct r1conf {
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struct mddev *mddev;
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struct raid1_info *mirrors; /* twice 'raid_disks' to
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* allow for replacements.
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*/
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int raid_disks;
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spinlock_t device_lock;
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/* list of 'struct r1bio' that need to be processed by raid1d,
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* whether to retry a read, writeout a resync or recovery
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* block, or anything else.
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*/
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struct list_head retry_list;
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/* A separate list of r1bio which just need raid_end_bio_io called.
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* This mustn't happen for writes which had any errors if the superblock
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* needs to be written.
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*/
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struct list_head bio_end_io_list;
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/* queue pending writes to be submitted on unplug */
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struct bio_list pending_bio_list;
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int pending_count;
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/* for use when syncing mirrors:
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* We don't allow both normal IO and resync/recovery IO at
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* the same time - resync/recovery can only happen when there
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* is no other IO. So when either is active, the other has to wait.
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* See more details description in raid1.c near raise_barrier().
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*/
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wait_queue_head_t wait_barrier;
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spinlock_t resync_lock;
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atomic_t nr_sync_pending;
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atomic_t *nr_pending;
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atomic_t *nr_waiting;
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atomic_t *nr_queued;
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atomic_t *barrier;
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int array_frozen;
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/* Set to 1 if a full sync is needed, (fresh device added).
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* Cleared when a sync completes.
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*/
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int fullsync;
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/* When the same as mddev->recovery_disabled we don't allow
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* recovery to be attempted as we expect a read error.
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*/
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int recovery_disabled;
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/* poolinfo contains information about the content of the
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* mempools - it changes when the array grows or shrinks
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*/
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struct pool_info *poolinfo;
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mempool_t r1bio_pool;
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mempool_t r1buf_pool;
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struct bio_set bio_split;
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/* temporary buffer to synchronous IO when attempting to repair
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* a read error.
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*/
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struct page *tmppage;
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/* When taking over an array from a different personality, we store
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* the new thread here until we fully activate the array.
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*/
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struct md_thread *thread;
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/* Keep track of cluster resync window to send to other
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* nodes.
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*/
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sector_t cluster_sync_low;
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sector_t cluster_sync_high;
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};
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/*
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* this is our 'private' RAID1 bio.
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*
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* it contains information about what kind of IO operations were started
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* for this RAID1 operation, and about their status:
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*/
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struct r1bio {
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atomic_t remaining; /* 'have we finished' count,
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* used from IRQ handlers
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*/
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atomic_t behind_remaining; /* number of write-behind ios remaining
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* in this BehindIO request
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*/
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sector_t sector;
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int sectors;
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unsigned long state;
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struct mddev *mddev;
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/*
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* original bio going to /dev/mdx
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*/
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struct bio *master_bio;
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/*
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* if the IO is in READ direction, then this is where we read
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*/
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int read_disk;
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struct list_head retry_list;
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/*
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* When R1BIO_BehindIO is set, we store pages for write behind
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* in behind_master_bio.
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*/
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struct bio *behind_master_bio;
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/*
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* if the IO is in WRITE direction, then multiple bios are used.
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* We choose the number when they are allocated.
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*/
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struct bio *bios[0];
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/* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
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};
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/* bits for r1bio.state */
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enum r1bio_state {
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R1BIO_Uptodate,
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R1BIO_IsSync,
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R1BIO_Degraded,
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R1BIO_BehindIO,
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/* Set ReadError on bios that experience a readerror so that
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* raid1d knows what to do with them.
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*/
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R1BIO_ReadError,
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/* For write-behind requests, we call bi_end_io when
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* the last non-write-behind device completes, providing
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* any write was successful. Otherwise we call when
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* any write-behind write succeeds, otherwise we call
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* with failure when last write completes (and all failed).
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* Record that bi_end_io was called with this flag...
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*/
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R1BIO_Returned,
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/* If a write for this request means we can clear some
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* known-bad-block records, we set this flag
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*/
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R1BIO_MadeGood,
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R1BIO_WriteError,
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R1BIO_FailFast,
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};
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static inline int sector_to_idx(sector_t sector)
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{
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return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
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BARRIER_BUCKETS_NR_BITS);
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}
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#endif
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