34db0cd60f
RAID1 and RAID10 handle write requests by queuing them for handling by a separate thread. This is because when a write-intent-bitmap is active we might need to update the bitmap first, so it is good to queue a lot of writes, then do one big bitmap update for them all. However writeback request devices to appear to be congested after a while so it can make some guesstimate of throughput. The infinite queue defeats that (note that RAID5 has already has a finite queue so it doesn't suffer from this problem). So impose a limit on the number of pending write requests. By default it is 1024 which seems to be generally suitable. Make it configurable via module option just in case someone finds a regression. Signed-off-by: NeilBrown <neilb@suse.de>
138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
#ifndef _RAID10_H
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#define _RAID10_H
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struct mirror_info {
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struct md_rdev *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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struct r10conf {
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struct mddev *mddev;
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struct mirror_info *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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int pending_count;
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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 md_thread *thread;
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};
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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 {
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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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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_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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/* When we successfully write to a known bad-block, we need to remove the
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* bad-block marking which must be done from process context. So we record
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* the success by setting devs[n].bio to IO_MADE_GOOD
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*/
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#define IO_MADE_GOOD ((struct bio *)2)
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#define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
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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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/* 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 R10BIO_MadeGood 5
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#define R10BIO_WriteError 6
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#endif
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