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856e08e237
This patch just covers the basic read path:
1/ read_balance needs to check for badblocks, and return not only
the chosen slot, but also how many good blocks are available
there.
2/ read submission must be ready to issue multiple reads to
different devices as different bad blocks on different devices
could mean that a single large read cannot be served by any one
device, but can still be served by the array.
This requires keeping count of the number of outstanding requests
per bio. This count is stored in 'bi_phys_segments'
On read error we currently just fail the request if another target
cannot handle the whole request. Next patch refines that a bit.
Signed-off-by: NeilBrown <neilb@suse.de>
132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
#ifndef _RAID10_H
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#define _RAID10_H
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typedef struct mirror_info mirror_info_t;
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struct mirror_info {
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mdk_rdev_t *rdev;
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sector_t head_position;
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int recovery_disabled; /* matches
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* mddev->recovery_disabled
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* when we shouldn't try
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* recovering this device.
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*/
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};
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typedef struct r10bio_s r10bio_t;
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struct r10_private_data_s {
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mddev_t *mddev;
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mirror_info_t *mirrors;
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int raid_disks;
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spinlock_t device_lock;
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/* geometry */
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int near_copies; /* number of copies laid out raid0 style */
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int far_copies; /* number of copies laid out
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* at large strides across drives
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*/
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int far_offset; /* far_copies are offset by 1 stripe
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* instead of many
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*/
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int copies; /* near_copies * far_copies.
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* must be <= raid_disks
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*/
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sector_t stride; /* distance between far copies.
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* This is size / far_copies unless
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* far_offset, in which case it is
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* 1 stripe.
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*/
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sector_t dev_sectors; /* temp copy of mddev->dev_sectors */
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int chunk_shift; /* shift from chunks to sectors */
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sector_t chunk_mask;
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struct list_head retry_list;
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/* queue pending writes and submit them on unplug */
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struct bio_list pending_bio_list;
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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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sector_t next_resync;
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int fullsync; /* set to 1 if a full sync is needed,
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* (fresh device added).
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* Cleared when a sync completes.
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*/
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wait_queue_head_t wait_barrier;
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mempool_t *r10bio_pool;
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mempool_t *r10buf_pool;
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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 mdk_thread_s *thread;
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};
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typedef struct r10_private_data_s conf_t;
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/*
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* this is our 'private' RAID10 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 RAID10 operation, and about their status:
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*/
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struct r10bio_s {
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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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sector_t sector; /* virtual sector number */
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int sectors;
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unsigned long state;
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mddev_t *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_slot;
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struct list_head retry_list;
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/*
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* if the IO is in WRITE direction, then multiple bios are used,
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* one for each copy.
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* When resyncing we also use one for each copy.
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* When reconstructing, we use 2 bios, one for read, one for write.
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* We choose the number when they are allocated.
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*/
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struct {
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struct bio *bio;
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sector_t addr;
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int devnum;
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} devs[0];
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};
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/* when we get a read error on a read-only array, we redirect to another
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* device without failing the first device, or trying to over-write to
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* correct the read error. To keep track of bad blocks on a per-bio
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* level, we store IO_BLOCKED in the appropriate 'bios' pointer
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*/
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#define IO_BLOCKED ((struct bio*)1)
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/* bits for r10bio.state */
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#define R10BIO_Uptodate 0
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#define R10BIO_IsSync 1
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#define R10BIO_IsRecover 2
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#define R10BIO_Degraded 3
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/* Set ReadError on bios that experience a read error
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* so that raid10d knows what to do with them.
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*/
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#define R10BIO_ReadError 4
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#endif
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