176 lines
5.1 KiB
C
176 lines
5.1 KiB
C
#ifndef _RAID1_H
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#define _RAID1_H
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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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/* During resync, read_balancing is only allowed on the part
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* of the array that has been resynced. 'next_resync' tells us
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* where that is.
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*/
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sector_t next_resync;
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/* When raid1 starts resync, we divide array into four partitions
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* |---------|--------------|---------------------|-------------|
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* next_resync start_next_window end_window
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* start_next_window = next_resync + NEXT_NORMALIO_DISTANCE
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* end_window = start_next_window + NEXT_NORMALIO_DISTANCE
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* current_window_requests means the count of normalIO between
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* start_next_window and end_window.
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* next_window_requests means the count of normalIO after end_window.
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* */
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sector_t start_next_window;
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int current_window_requests;
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int next_window_requests;
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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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/* 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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int nr_pending;
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int nr_waiting;
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int nr_queued;
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int 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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/* 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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};
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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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sector_t start_next_window;
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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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/* Next two are only valid when R1BIO_BehindIO is set */
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struct bio_vec *behind_bvecs;
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int behind_page_count;
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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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#define R1BIO_Uptodate 0
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#define R1BIO_IsSync 1
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#define R1BIO_Degraded 2
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#define R1BIO_BehindIO 3
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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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#define R1BIO_ReadError 4
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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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#define R1BIO_Returned 6
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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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#define R1BIO_MadeGood 7
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#define R1BIO_WriteError 8
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extern int md_raid1_congested(struct mddev *mddev, int bits);
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#endif
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