diff options
Diffstat (limited to 'drivers/md/raid5.c')
| -rw-r--r-- | drivers/md/raid5.c | 1965 |
1 files changed, 1965 insertions, 0 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c new file mode 100644 index 000000000000..52c3a81c4aa7 --- /dev/null +++ b/drivers/md/raid5.c @@ -0,0 +1,1965 @@ +/* + * raid5.c : Multiple Devices driver for Linux + * Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman + * Copyright (C) 1999, 2000 Ingo Molnar + * + * RAID-5 management functions. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * You should have received a copy of the GNU General Public License + * (for example /usr/src/linux/COPYING); if not, write to the Free + * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/raid/raid5.h> +#include <linux/highmem.h> +#include <linux/bitops.h> +#include <asm/atomic.h> + +/* + * Stripe cache + */ + +#define NR_STRIPES 256 +#define STRIPE_SIZE PAGE_SIZE +#define STRIPE_SHIFT (PAGE_SHIFT - 9) +#define STRIPE_SECTORS (STRIPE_SIZE>>9) +#define IO_THRESHOLD 1 +#define HASH_PAGES 1 +#define HASH_PAGES_ORDER 0 +#define NR_HASH (HASH_PAGES * PAGE_SIZE / sizeof(struct stripe_head *)) +#define HASH_MASK (NR_HASH - 1) + +#define stripe_hash(conf, sect) ((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]) + +/* bio's attached to a stripe+device for I/O are linked together in bi_sector + * order without overlap. There may be several bio's per stripe+device, and + * a bio could span several devices. + * When walking this list for a particular stripe+device, we must never proceed + * beyond a bio that extends past this device, as the next bio might no longer + * be valid. + * This macro is used to determine the 'next' bio in the list, given the sector + * of the current stripe+device + */ +#define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL) +/* + * The following can be used to debug the driver + */ +#define RAID5_DEBUG 0 +#define RAID5_PARANOIA 1 +#if RAID5_PARANOIA && defined(CONFIG_SMP) +# define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock) +#else +# define CHECK_DEVLOCK() +#endif + +#define PRINTK(x...) ((void)(RAID5_DEBUG && printk(x))) +#if RAID5_DEBUG +#define inline +#define __inline__ +#endif + +static void print_raid5_conf (raid5_conf_t *conf); + +static inline void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh) +{ + if (atomic_dec_and_test(&sh->count)) { + if (!list_empty(&sh->lru)) + BUG(); + if (atomic_read(&conf->active_stripes)==0) + BUG(); + if (test_bit(STRIPE_HANDLE, &sh->state)) { + if (test_bit(STRIPE_DELAYED, &sh->state)) + list_add_tail(&sh->lru, &conf->delayed_list); + else + list_add_tail(&sh->lru, &conf->handle_list); + md_wakeup_thread(conf->mddev->thread); + } else { + if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) { + atomic_dec(&conf->preread_active_stripes); + if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) + md_wakeup_thread(conf->mddev->thread); + } + list_add_tail(&sh->lru, &conf->inactive_list); + atomic_dec(&conf->active_stripes); + if (!conf->inactive_blocked || + atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4)) + wake_up(&conf->wait_for_stripe); + } + } +} +static void release_stripe(struct stripe_head *sh) +{ + raid5_conf_t *conf = sh->raid_conf; + unsigned long flags; + + spin_lock_irqsave(&conf->device_lock, flags); + __release_stripe(conf, sh); + spin_unlock_irqrestore(&conf->device_lock, flags); +} + +static void remove_hash(struct stripe_head *sh) +{ + PRINTK("remove_hash(), stripe %llu\n", (unsigned long long)sh->sector); + + if (sh->hash_pprev) { + if (sh->hash_next) + sh->hash_next->hash_pprev = sh->hash_pprev; + *sh->hash_pprev = sh->hash_next; + sh->hash_pprev = NULL; + } +} + +static __inline__ void insert_hash(raid5_conf_t *conf, struct stripe_head *sh) +{ + struct stripe_head **shp = &stripe_hash(conf, sh->sector); + + PRINTK("insert_hash(), stripe %llu\n", (unsigned long long)sh->sector); + + CHECK_DEVLOCK(); + if ((sh->hash_next = *shp) != NULL) + (*shp)->hash_pprev = &sh->hash_next; + *shp = sh; + sh->hash_pprev = shp; +} + + +/* find an idle stripe, make sure it is unhashed, and return it. */ +static struct stripe_head *get_free_stripe(raid5_conf_t *conf) +{ + struct stripe_head *sh = NULL; + struct list_head *first; + + CHECK_DEVLOCK(); + if (list_empty(&conf->inactive_list)) + goto out; + first = conf->inactive_list.next; + sh = list_entry(first, struct stripe_head, lru); + list_del_init(first); + remove_hash(sh); + atomic_inc(&conf->active_stripes); +out: + return sh; +} + +static void shrink_buffers(struct stripe_head *sh, int num) +{ + struct page *p; + int i; + + for (i=0; i<num ; i++) { + p = sh->dev[i].page; + if (!p) + continue; + sh->dev[i].page = NULL; + page_cache_release(p); + } +} + +static int grow_buffers(struct stripe_head *sh, int num) +{ + int i; + + for (i=0; i<num; i++) { + struct page *page; + + if (!(page = alloc_page(GFP_KERNEL))) { + return 1; + } + sh->dev[i].page = page; + } + return 0; +} + +static void raid5_build_block (struct stripe_head *sh, int i); + +static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx) +{ + raid5_conf_t *conf = sh->raid_conf; + int disks = conf->raid_disks, i; + + if (atomic_read(&sh->count) != 0) + BUG(); + if (test_bit(STRIPE_HANDLE, &sh->state)) + BUG(); + + CHECK_DEVLOCK(); + PRINTK("init_stripe called, stripe %llu\n", + (unsigned long long)sh->sector); + + remove_hash(sh); + + sh->sector = sector; + sh->pd_idx = pd_idx; + sh->state = 0; + + for (i=disks; i--; ) { + struct r5dev *dev = &sh->dev[i]; + + if (dev->toread || dev->towrite || dev->written || + test_bit(R5_LOCKED, &dev->flags)) { + printk("sector=%llx i=%d %p %p %p %d\n", + (unsigned long long)sh->sector, i, dev->toread, + dev->towrite, dev->written, + test_bit(R5_LOCKED, &dev->flags)); + BUG(); + } + dev->flags = 0; + raid5_build_block(sh, i); + } + insert_hash(conf, sh); +} + +static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector) +{ + struct stripe_head *sh; + + CHECK_DEVLOCK(); + PRINTK("__find_stripe, sector %llu\n", (unsigned long long)sector); + for (sh = stripe_hash(conf, sector); sh; sh = sh->hash_next) + if (sh->sector == sector) + return sh; + PRINTK("__stripe %llu not in cache\n", (unsigned long long)sector); + return NULL; +} + +static void unplug_slaves(mddev_t *mddev); +static void raid5_unplug_device(request_queue_t *q); + +static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, + int pd_idx, int noblock) +{ + struct stripe_head *sh; + + PRINTK("get_stripe, sector %llu\n", (unsigned long long)sector); + + spin_lock_irq(&conf->device_lock); + + do { + sh = __find_stripe(conf, sector); + if (!sh) { + if (!conf->inactive_blocked) + sh = get_free_stripe(conf); + if (noblock && sh == NULL) + break; + if (!sh) { + conf->inactive_blocked = 1; + wait_event_lock_irq(conf->wait_for_stripe, + !list_empty(&conf->inactive_list) && + (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4) + || !conf->inactive_blocked), + conf->device_lock, + unplug_slaves(conf->mddev); + ); + conf->inactive_blocked = 0; + } else + init_stripe(sh, sector, pd_idx); + } else { + if (atomic_read(&sh->count)) { + if (!list_empty(&sh->lru)) + BUG(); + } else { + if (!test_bit(STRIPE_HANDLE, &sh->state)) + atomic_inc(&conf->active_stripes); + if (list_empty(&sh->lru)) + BUG(); + list_del_init(&sh->lru); + } + } + } while (sh == NULL); + + if (sh) + atomic_inc(&sh->count); + + spin_unlock_irq(&conf->device_lock); + return sh; +} + +static int grow_stripes(raid5_conf_t *conf, int num) +{ + struct stripe_head *sh; + kmem_cache_t *sc; + int devs = conf->raid_disks; + + sprintf(conf->cache_name, "raid5/%s", mdname(conf->mddev)); + + sc = kmem_cache_create(conf->cache_name, + sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev), + 0, 0, NULL, NULL); + if (!sc) + return 1; + conf->slab_cache = sc; + while (num--) { + sh = kmem_cache_alloc(sc, GFP_KERNEL); + if (!sh) + return 1; + memset(sh, 0, sizeof(*sh) + (devs-1)*sizeof(struct r5dev)); + sh->raid_conf = conf; + spin_lock_init(&sh->lock); + + if (grow_buffers(sh, conf->raid_disks)) { + shrink_buffers(sh, conf->raid_disks); + kmem_cache_free(sc, sh); + return 1; + } + /* we just created an active stripe so... */ + atomic_set(&sh->count, 1); + atomic_inc(&conf->active_stripes); + INIT_LIST_HEAD(&sh->lru); + release_stripe(sh); + } + return 0; +} + +static void shrink_stripes(raid5_conf_t *conf) +{ + struct stripe_head *sh; + + while (1) { + spin_lock_irq(&conf->device_lock); + sh = get_free_stripe(conf); + spin_unlock_irq(&conf->device_lock); + if (!sh) + break; + if (atomic_read(&sh->count)) + BUG(); + shrink_buffers(sh, conf->raid_disks); + kmem_cache_free(conf->slab_cache, sh); + atomic_dec(&conf->active_stripes); + } + kmem_cache_destroy(conf->slab_cache); + conf->slab_cache = NULL; +} + +static int raid5_end_read_request (struct bio * bi, unsigned int bytes_done, + int error) +{ + struct stripe_head *sh = bi->bi_private; + raid5_conf_t *conf = sh->raid_conf; + int disks = conf->raid_disks, i; + int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags); + + if (bi->bi_size) + return 1; + + for (i=0 ; i<disks; i++) + if (bi == &sh->dev[i].req) + break; + + PRINTK("end_read_request %llu/%d, count: %d, uptodate %d.\n", + (unsigned long long)sh->sector, i, atomic_read(&sh->count), + uptodate); + if (i == disks) { + BUG(); + return 0; + } + + if (uptodate) { +#if 0 + struct bio *bio; + unsigned long flags; + spin_lock_irqsave(&conf->device_lock, flags); + /* we can return a buffer if we bypassed the cache or + * if the top buffer is not in highmem. If there are + * multiple buffers, leave the extra work to + * handle_stripe + */ + buffer = sh->bh_read[i]; + if (buffer && + (!PageHighMem(buffer->b_page) + || buffer->b_page == bh->b_page ) + ) { + sh->bh_read[i] = buffer->b_reqnext; + buffer->b_reqnext = NULL; + } else + buffer = NULL; + spin_unlock_irqrestore(&conf->device_lock, flags); + if (sh->bh_page[i]==bh->b_page) + set_buffer_uptodate(bh); + if (buffer) { + if (buffer->b_page != bh->b_page) + memcpy(buffer->b_data, bh->b_data, bh->b_size); + buffer->b_end_io(buffer, 1); + } +#else + set_bit(R5_UPTODATE, &sh->dev[i].flags); +#endif + } else { + md_error(conf->mddev, conf->disks[i].rdev); + clear_bit(R5_UPTODATE, &sh->dev[i].flags); + } + rdev_dec_pending(conf->disks[i].rdev, conf->mddev); +#if 0 + /* must restore b_page before unlocking buffer... */ + if (sh->bh_page[i] != bh->b_page) { + bh->b_page = sh->bh_page[i]; + bh->b_data = page_address(bh->b_page); + clear_buffer_uptodate(bh); + } +#endif + clear_bit(R5_LOCKED, &sh->dev[i].flags); + set_bit(STRIPE_HANDLE, &sh->state); + release_stripe(sh); + return 0; +} + +static int raid5_end_write_request (struct bio *bi, unsigned int bytes_done, + int error) +{ + struct stripe_head *sh = bi->bi_private; + raid5_conf_t *conf = sh->raid_conf; + int disks = conf->raid_disks, i; + unsigned long flags; + int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags); + + if (bi->bi_size) + return 1; + + for (i=0 ; i<disks; i++) + if (bi == &sh->dev[i].req) + break; + + PRINTK("end_write_request %llu/%d, count %d, uptodate: %d.\n", + (unsigned long long)sh->sector, i, atomic_read(&sh->count), + uptodate); + if (i == disks) { + BUG(); + return 0; + } + + spin_lock_irqsave(&conf->device_lock, flags); + if (!uptodate) + md_error(conf->mddev, conf->disks[i].rdev); + + rdev_dec_pending(conf->disks[i].rdev, conf->mddev); + + clear_bit(R5_LOCKED, &sh->dev[i].flags); + set_bit(STRIPE_HANDLE, &sh->state); + __release_stripe(conf, sh); + spin_unlock_irqrestore(&conf->device_lock, flags); + return 0; +} + + +static sector_t compute_blocknr(struct stripe_head *sh, int i); + +static void raid5_build_block (struct stripe_head *sh, int i) +{ + struct r5dev *dev = &sh->dev[i]; + + bio_init(&dev->req); + dev->req.bi_io_vec = &dev->vec; + dev->req.bi_vcnt++; + dev->req.bi_max_vecs++; + dev->vec.bv_page = dev->page; + dev->vec.bv_len = STRIPE_SIZE; + dev->vec.bv_offset = 0; + + dev->req.bi_sector = sh->sector; + dev->req.bi_private = sh; + + dev->flags = 0; + if (i != sh->pd_idx) + dev->sector = compute_blocknr(sh, i); +} + +static void error(mddev_t *mddev, mdk_rdev_t *rdev) +{ + char b[BDEVNAME_SIZE]; + raid5_conf_t *conf = (raid5_conf_t *) mddev->private; + PRINTK("raid5: error called\n"); + + if (!rdev->faulty) { + mddev->sb_dirty = 1; + if (rdev->in_sync) { + conf->working_disks--; + mddev->degraded++; + conf->failed_disks++; + rdev->in_sync = 0; + /* + * if recovery was running, make sure it aborts. + */ + set_bit(MD_RECOVERY_ERR, &mddev->recovery); + } + rdev->faulty = 1; + printk (KERN_ALERT + "raid5: Disk failure on %s, disabling device." + " Operation continuing on %d devices\n", + bdevname(rdev->bdev,b), conf->working_disks); + } +} + +/* + * Input: a 'big' sector number, + * Output: index of the data and parity disk, and the sector # in them. + */ +static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks, + unsigned int data_disks, unsigned int * dd_idx, + unsigned int * pd_idx, raid5_conf_t *conf) +{ + long stripe; + unsigned long chunk_number; + unsigned int chunk_offset; + sector_t new_sector; + int sectors_per_chunk = conf->chunk_size >> 9; + + /* First compute the information on this sector */ + + /* + * Compute the chunk number and the sector offset inside the chunk + */ + chunk_offset = sector_div(r_sector, sectors_per_chunk); + chunk_number = r_sector; + BUG_ON(r_sector != chunk_number); + + /* + * Compute the stripe number + */ + stripe = chunk_number / data_disks; + + /* + * Compute the data disk and parity disk indexes inside the stripe + */ + *dd_idx = chunk_number % data_disks; + + /* + * Select the parity disk based on the user selected algorithm. + */ + if (conf->level == 4) + *pd_idx = data_disks; + else switch (conf->algorithm) { + case ALGORITHM_LEFT_ASYMMETRIC: + *pd_idx = data_disks - stripe % raid_disks; + if (*dd_idx >= *pd_idx) + (*dd_idx)++; + break; + case ALGORITHM_RIGHT_ASYMMETRIC: + *pd_idx = stripe % raid_disks; + if (*dd_idx >= *pd_idx) + (*dd_idx)++; + break; + case ALGORITHM_LEFT_SYMMETRIC: + *pd_idx = data_disks - stripe % raid_disks; + *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks; + break; + case ALGORITHM_RIGHT_SYMMETRIC: + *pd_idx = stripe % raid_disks; + *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks; + break; + default: + printk("raid5: unsupported algorithm %d\n", + conf->algorithm); + } + + /* + * Finally, compute the new sector number + */ + new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset; + return new_sector; +} + + +static sector_t compute_blocknr(struct stripe_head *sh, int i) +{ + raid5_conf_t *conf = sh->raid_conf; + int raid_disks = conf->raid_disks, data_disks = raid_disks - 1; + sector_t new_sector = sh->sector, check; + int sectors_per_chunk = conf->chunk_size >> 9; + sector_t stripe; + int chunk_offset; + int chunk_number, dummy1, dummy2, dd_idx = i; + sector_t r_sector; + + chunk_offset = sector_div(new_sector, sectors_per_chunk); + stripe = new_sector; + BUG_ON(new_sector != stripe); + + + switch (conf->algorithm) { + case ALGORITHM_LEFT_ASYMMETRIC: + case ALGORITHM_RIGHT_ASYMMETRIC: + if (i > sh->pd_idx) + i--; + break; + case ALGORITHM_LEFT_SYMMETRIC: + case ALGORITHM_RIGHT_SYMMETRIC: + if (i < sh->pd_idx) + i += raid_disks; + i -= (sh->pd_idx + 1); + break; + default: + printk("raid5: unsupported algorithm %d\n", + conf->algorithm); + } + + chunk_number = stripe * data_disks + i; + r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset; + + check = raid5_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf); + if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) { + printk("compute_blocknr: map not correct\n"); + return 0; + } + return r_sector; +} + + + +/* + * Copy data between a page in the stripe cache, and a bio. + * There are no alignment or size guarantees between the page or the + * bio except that there is some overlap. + * All iovecs in the bio must be considered. + */ +static void copy_data(int frombio, struct bio *bio, + struct page *page, + sector_t sector) +{ + char *pa = page_address(page); + struct bio_vec *bvl; + int i; + int page_offset; + + if (bio->bi_sector >= sector) + page_offset = (signed)(bio->bi_sector - sector) * 512; + else + page_offset = (signed)(sector - bio->bi_sector) * -512; + bio_for_each_segment(bvl, bio, i) { + int len = bio_iovec_idx(bio,i)->bv_len; + int clen; + int b_offset = 0; + + if (page_offset < 0) { + b_offset = -page_offset; + page_offset += b_offset; + len -= b_offset; + } + + if (len > 0 && page_offset + len > STRIPE_SIZE) + clen = STRIPE_SIZE - page_offset; + else clen = len; + + if (clen > 0) { + char *ba = __bio_kmap_atomic(bio, i, KM_USER0); + if (frombio) + memcpy(pa+page_offset, ba+b_offset, clen); + else + memcpy(ba+b_offset, pa+page_offset, clen); + __bio_kunmap_atomic(ba, KM_USER0); + } + if (clen < len) /* hit end of page */ + break; + page_offset += len; + } +} + +#define check_xor() do { \ + if (count == MAX_XOR_BLOCKS) { \ + xor_block(count, STRIPE_SIZE, ptr); \ + count = 1; \ + } \ + } while(0) + + +static void compute_block(struct stripe_head *sh, int dd_idx) +{ + raid5_conf_t *conf = sh->raid_conf; + int i, count, disks = conf->raid_disks; + void *ptr[MAX_XOR_BLOCKS], *p; + + PRINTK("compute_block, stripe %llu, idx %d\n", + (unsigned long long)sh->sector, dd_idx); + + ptr[0] = page_address(sh->dev[dd_idx].page); + memset(ptr[0], 0, STRIPE_SIZE); + count = 1; + for (i = disks ; i--; ) { + if (i == dd_idx) + continue; + p = page_address(sh->dev[i].page); + if (test_bit(R5_UPTODATE, &sh->dev[i].flags)) + ptr[count++] = p; + else + printk("compute_block() %d, stripe %llu, %d" + " not present\n", dd_idx, + (unsigned long long)sh->sector, i); + + check_xor(); + } + if (count != 1) + xor_block(count, STRIPE_SIZE, ptr); + set_bit(R5_UPTODATE, &sh->dev[dd_idx].flags); +} + +static void compute_parity(struct stripe_head *sh, int method) +{ + raid5_conf_t *conf = sh->raid_conf; + int i, pd_idx = sh->pd_idx, disks = conf->raid_disks, count; + void *ptr[MAX_XOR_BLOCKS]; + struct bio *chosen; + + PRINTK("compute_parity, stripe %llu, method %d\n", + (unsigned long long)sh->sector, method); + + count = 1; + ptr[0] = page_address(sh->dev[pd_idx].page); + switch(method) { + case READ_MODIFY_WRITE: + if (!test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags)) + BUG(); + for (i=disks ; i-- ;) { + if (i==pd_idx) + continue; + if (sh->dev[i].towrite && + test_bit(R5_UPTODATE, &sh->dev[i].flags)) { + ptr[count++] = page_address(sh->dev[i].page); + chosen = sh->dev[i].towrite; + sh->dev[i].towrite = NULL; + + if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags)) + wake_up(&conf->wait_for_overlap); + + if (sh->dev[i].written) BUG(); + sh->dev[i].written = chosen; + check_xor(); + } + } + break; + case RECONSTRUCT_WRITE: + memset(ptr[0], 0, STRIPE_SIZE); + for (i= disks; i-- ;) + if (i!=pd_idx && sh->dev[i].towrite) { + chosen = sh->dev[i].towrite; + sh->dev[i].towrite = NULL; + + if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags)) + wake_up(&conf->wait_for_overlap); + + if (sh->dev[i].written) BUG(); + sh->dev[i].written = chosen; + } + break; + case CHECK_PARITY: + break; + } + if (count>1) { + xor_block(count, STRIPE_SIZE, ptr); + count = 1; + } + + for (i = disks; i--;) + if (sh->dev[i].written) { + sector_t sector = sh->dev[i].sector; + struct bio *wbi = sh->dev[i].written; + while (wbi && wbi->bi_sector < sector + STRIPE_SECTORS) { + copy_data(1, wbi, sh->dev[i].page, sector); + wbi = r5_next_bio(wbi, sector); + } + + set_bit(R5_LOCKED, &sh->dev[i].flags); + set_bit(R5_UPTODATE, &sh->dev[i].flags); + } + + switch(method) { + case RECONSTRUCT_WRITE: + case CHECK_PARITY: + for (i=disks; i--;) + if (i != pd_idx) { + ptr[count++] = page_address(sh->dev[i].page); + check_xor(); + } + break; + case READ_MODIFY_WRITE: + for (i = disks; i--;) + if (sh->dev[i].written) { + ptr[count++] = page_address(sh->dev[i].page); + check_xor(); + } + } + if (count != 1) + xor_block(count, STRIPE_SIZE, ptr); + + if (method != CHECK_PARITY) { + set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags); + set_bit(R5_LOCKED, &sh->dev[pd_idx].flags); + } else + clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags); +} + +/* + * Each stripe/dev can have one or more bion attached. + * toread/towrite point to the first in a chain. + * The bi_next chain must be in order. + */ +static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite) +{ + struct bio **bip; + raid5_conf_t *conf = sh->raid_conf; + + PRINTK("adding bh b#%llu to stripe s#%llu\n", + (unsigned long long)bi->bi_sector, + (unsigned long long)sh->sector); + + + spin_lock(&sh->lock); + spin_lock_irq(&conf->device_lock); + if (forwrite) + bip = &sh->dev[dd_idx].towrite; + else + bip = &sh->dev[dd_idx].toread; + while (*bip && (*bip)->bi_sector < bi->bi_sector) { + if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector) + goto overlap; + bip = & (*bip)->bi_next; + } + if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9)) + goto overlap; + + if (*bip && bi->bi_next && (*bip) != bi->bi_next) + BUG(); + if (*bip) + bi->bi_next = *bip; + *bip = bi; + bi->bi_phys_segments ++; + spin_unlock_irq(&conf->device_lock); + spin_unlock(&sh->lock); + + PRINTK("added bi b#%llu to stripe s#%llu, disk %d.\n", + (unsigned long long)bi->bi_sector, + (unsigned long long)sh->sector, dd_idx); + + if (forwrite) { + /* check if page is covered */ + sector_t sector = sh->dev[dd_idx].sector; + for (bi=sh->dev[dd_idx].towrite; + sector < sh->dev[dd_idx].sector + STRIPE_SECTORS && + bi && bi->bi_sector <= sector; + bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) { + if (bi->bi_sector + (bi->bi_size>>9) >= sector) + sector = bi->bi_sector + (bi->bi_size>>9); + } + if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS) + set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags); + } + return 1; + + overlap: + set_bit(R5_Overlap, &sh->dev[dd_idx].flags); + spin_unlock_irq(&conf->device_lock); + spin_unlock(&sh->lock); + return 0; +} + + +/* + * handle_stripe - do things to a stripe. + * + * We lock the stripe and then examine the state of various bits + * to see what needs to be done. + * Possible results: + * return some read request which now have data + * return some write requests which are safely on disc + * schedule a read on some buffers + * schedule a write of some buffers + * return confirmation of parity correctness + * + * Parity calculations are done inside the stripe lock + * buffers are taken off read_list or write_list, and bh_cache buffers + * get BH_Lock set before the stripe lock is released. + * + */ + +static void handle_stripe(struct stripe_head *sh) +{ + raid5_conf_t *conf = sh->raid_conf; + int disks = conf->raid_disks; + struct bio *return_bi= NULL; + struct bio *bi; + int i; + int syncing; + int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0; + int non_overwrite = 0; + int failed_num=0; + struct r5dev *dev; + + PRINTK("handling stripe %llu, cnt=%d, pd_idx=%d\n", + (unsigned long long)sh->sector, atomic_read(&sh->count), + sh->pd_idx); + + spin_lock(&sh->lock); + clear_bit(STRIPE_HANDLE, &sh->state); + clear_bit(STRIPE_DELAYED, &sh->state); + + syncing = test_bit(STRIPE_SYNCING, &sh->state); + /* Now to look around and see what can be done */ + + for (i=disks; i--; ) { + mdk_rdev_t *rdev; + dev = &sh->dev[i]; + clear_bit(R5_Insync, &dev->flags); + clear_bit(R5_Syncio, &dev->flags); + + PRINTK("check %d: state 0x%lx read %p write %p written %p\n", + i, dev->flags, dev->toread, dev->towrite, dev->written); + /* maybe we can reply to a read */ + if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) { + struct bio *rbi, *rbi2; + PRINTK("Return read for disc %d\n", i); + spin_lock_irq(&conf->device_lock); + rbi = dev->toread; + dev->toread = NULL; + if (test_and_clear_bit(R5_Overlap, &dev->flags)) + wake_up(&conf->wait_for_overlap); + spin_unlock_irq(&conf->device_lock); + while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) { + copy_data(0, rbi, dev->page, dev->sector); + rbi2 = r5_next_bio(rbi, dev->sector); + spin_lock_irq(&conf->device_lock); + if (--rbi->bi_phys_segments == 0) { + rbi->bi_next = return_bi; + return_bi = rbi; + } + spin_unlock_irq(&conf->device_lock); + rbi = rbi2; + } + } + + /* now count some things */ + if (test_bit(R5_LOCKED, &dev->flags)) locked++; + if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++; + + + if (dev->toread) to_read++; + if (dev->towrite) { + to_write++; + if (!test_bit(R5_OVERWRITE, &dev->flags)) + non_overwrite++; + } + if (dev->written) written++; + rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */ + if (!rdev || !rdev->in_sync) { + failed++; + failed_num = i; + } else + set_bit(R5_Insync, &dev->flags); + } + PRINTK("locked=%d uptodate=%d to_read=%d" + " to_write=%d failed=%d failed_num=%d\n", + locked, uptodate, to_read, to_write, failed, failed_num); + /* check if the array has lost two devices and, if so, some requests might + * need to be failed + */ + if (failed > 1 && to_read+to_write+written) { + spin_lock_irq(&conf->device_lock); + for (i=disks; i--; ) { + /* fail all writes first */ + bi = sh->dev[i].towrite; + sh->dev[i].towrite = NULL; + if (bi) to_write--; + + if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags)) + wake_up(&conf->wait_for_overlap); + + while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){ + struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector); + clear_bit(BIO_UPTODATE, &bi->bi_flags); + if (--bi->bi_phys_segments == 0) { + md_write_end(conf->mddev); + bi->bi_next = return_bi; + return_bi = bi; + } + bi = nextbi; + } + /* and fail all 'written' */ + bi = sh->dev[i].written; + sh->dev[i].written = NULL; + while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS) { + struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector); + clear_bit(BIO_UPTODATE, &bi->bi_flags); + if (--bi->bi_phys_segments == 0) { + md_write_end(conf->mddev); + bi->bi_next = return_bi; + return_bi = bi; + } + bi = bi2; + } + + /* fail any reads if this device is non-operational */ + if (!test_bit(R5_Insync, &sh->dev[i].flags)) { + bi = sh->dev[i].toread; + sh->dev[i].toread = NULL; + if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags)) + wake_up(&conf->wait_for_overlap); + if (bi) to_read--; + while (bi && bi->bi_sector < sh->dev[i].sector + STRIPE_SECTORS){ + struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector); + clear_bit(BIO_UPTODATE, &bi->bi_flags); + if (--bi->bi_phys_segments == 0) { + bi->bi_next = return_bi; + return_bi = bi; + } + bi = nextbi; + } + } + } + spin_unlock_irq(&conf->device_lock); + } + if (failed > 1 && syncing) { + md_done_sync(conf->mddev, STRIPE_SECTORS,0); + clear_bit(STRIPE_SYNCING, &sh->state); + syncing = 0; + } + + /* might be able to return some write requests if the parity block + * is safe, or on a failed drive + */ + dev = &sh->dev[sh->pd_idx]; + if ( written && + ( (test_bit(R5_Insync, &dev->flags) && !test_bit(R5_LOCKED, &dev->flags) && + test_bit(R5_UPTODATE, &dev->flags)) + || (failed == 1 && failed_num == sh->pd_idx)) + ) { + /* any written block on an uptodate or failed drive can be returned. + * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but + * never LOCKED, so we don't need to test 'failed' directly. + */ + for (i=disks; i--; ) + if (sh->dev[i].written) { + dev = &sh->dev[i]; + if (!test_bit(R5_LOCKED, &dev->flags) && + test_bit(R5_UPTODATE, &dev->flags) ) { + /* We can return any write requests */ + struct bio *wbi, *wbi2; + PRINTK("Return write for disc %d\n", i); + spin_lock_irq(&conf->device_lock); + wbi = dev->written; + dev->written = NULL; + while (wbi && wbi->bi_sector < dev->sector + STRIPE_SECTORS) { + wbi2 = r5_next_bio(wbi, dev->sector); + if (--wbi->bi_phys_segments == 0) { + md_write_end(conf->mddev); + wbi->bi_next = return_bi; + return_bi = wbi; + } + wbi = wbi2; + } + spin_unlock_irq(&conf->device_lock); + } + } + } + + /* Now we might consider reading some blocks, either to check/generate + * parity, or to satisfy requests + * or to load a block that is being partially written. + */ + if (to_read || non_overwrite || (syncing && (uptodate < disks))) { + for (i=disks; i--;) { + dev = &sh->dev[i]; + if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) && + (dev->toread || + (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) || + syncing || + (failed && (sh->dev[failed_num].toread || + (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags)))) + ) + ) { + /* we would like to get this block, possibly + * by computing it, but we might not be able to + */ + if (uptodate == disks-1) { + PRINTK("Computing block %d\n", i); + compute_block(sh, i); + uptodate++; + } else if (test_bit(R5_Insync, &dev->flags)) { + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantread, &dev->flags); +#if 0 + /* if I am just reading this block and we don't have + a failed drive, or any pending writes then sidestep the cache */ + if (sh->bh_read[i] && !sh->bh_read[i]->b_reqnext && + ! syncing && !failed && !to_write) { + sh->bh_cache[i]->b_page = sh->bh_read[i]->b_page; + sh->bh_cache[i]->b_data = sh->bh_read[i]->b_data; + } +#endif + locked++; + PRINTK("Reading block %d (sync=%d)\n", + i, syncing); + if (syncing) + md_sync_acct(conf->disks[i].rdev->bdev, + STRIPE_SECTORS); + } + } + } + set_bit(STRIPE_HANDLE, &sh->state); + } + + /* now to consider writing and what else, if anything should be read */ + if (to_write) { + int rmw=0, rcw=0; + for (i=disks ; i--;) { + /* would I have to read this buffer for read_modify_write */ + dev = &sh->dev[i]; + if ((dev->towrite || i == sh->pd_idx) && + (!test_bit(R5_LOCKED, &dev->flags) +#if 0 +|| sh->bh_page[i]!=bh->b_page +#endif + ) && + !test_bit(R5_UPTODATE, &dev->flags)) { + if (test_bit(R5_Insync, &dev->flags) +/* && !(!mddev->insync && i == sh->pd_idx) */ + ) + rmw++; + else rmw += 2*disks; /* cannot read it */ + } + /* Would I have to read this buffer for reconstruct_write */ + if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx && + (!test_bit(R5_LOCKED, &dev->flags) +#if 0 +|| sh->bh_page[i] != bh->b_page +#endif + ) && + !test_bit(R5_UPTODATE, &dev->flags)) { + if (test_bit(R5_Insync, &dev->flags)) rcw++; + else rcw += 2*disks; + } + } + PRINTK("for sector %llu, rmw=%d rcw=%d\n", + (unsigned long long)sh->sector, rmw, rcw); + set_bit(STRIPE_HANDLE, &sh->state); + if (rmw < rcw && rmw > 0) + /* prefer read-modify-write, but need to get some data */ + for (i=disks; i--;) { + dev = &sh->dev[i]; + if ((dev->towrite || i == sh->pd_idx) && + !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) && + test_bit(R5_Insync, &dev->flags)) { + if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) + { + PRINTK("Read_old block %d for r-m-w\n", i); + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantread, &dev->flags); + locked++; + } else { + set_bit(STRIPE_DELAYED, &sh->state); + set_bit(STRIPE_HANDLE, &sh->state); + } + } + } + if (rcw <= rmw && rcw > 0) + /* want reconstruct write, but need to get some data */ + for (i=disks; i--;) { + dev = &sh->dev[i]; + if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx && + !test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) && + test_bit(R5_Insync, &dev->flags)) { + if (test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) + { + PRINTK("Read_old block %d for Reconstruct\n", i); + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantread, &dev->flags); + locked++; + } else { + set_bit(STRIPE_DELAYED, &sh->state); + set_bit(STRIPE_HANDLE, &sh->state); + } + } + } + /* now if nothing is locked, and if we have enough data, we can start a write request */ + if (locked == 0 && (rcw == 0 ||rmw == 0)) { + PRINTK("Computing parity...\n"); + compute_parity(sh, rcw==0 ? RECONSTRUCT_WRITE : READ_MODIFY_WRITE); + /* now every locked buffer is ready to be written */ + for (i=disks; i--;) + if (test_bit(R5_LOCKED, &sh->dev[i].flags)) { + PRINTK("Writing block %d\n", i); + locked++; + set_bit(R5_Wantwrite, &sh->dev[i].flags); + if (!test_bit(R5_Insync, &sh->dev[i].flags) + || (i==sh->pd_idx && failed == 0)) + set_bit(STRIPE_INSYNC, &sh->state); + } + if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) { + atomic_dec(&conf->preread_active_stripes); + if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) + md_wakeup_thread(conf->mddev->thread); + } + } + } + + /* maybe we need to check and possibly fix the parity for this stripe + * Any reads will already have been scheduled, so we just see if enough data + * is available + */ + if (syncing && locked == 0 && + !test_bit(STRIPE_INSYNC, &sh->state) && failed <= 1) { + set_bit(STRIPE_HANDLE, &sh->state); + if (failed == 0) { + char *pagea; + if (uptodate != disks) + BUG(); + compute_parity(sh, CHECK_PARITY); + uptodate--; + pagea = page_address(sh->dev[sh->pd_idx].page); + if ((*(u32*)pagea) == 0 && + !memcmp(pagea, pagea+4, STRIPE_SIZE-4)) { + /* parity is correct (on disc, not in buffer any more) */ + set_bit(STRIPE_INSYNC, &sh->state); + } + } + if (!test_bit(STRIPE_INSYNC, &sh->state)) { + if (failed==0) + failed_num = sh->pd_idx; + /* should be able to compute the missing block and write it to spare */ + if (!test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)) { + if (uptodate+1 != disks) + BUG(); + compute_block(sh, failed_num); + uptodate++; + } + if (uptodate != disks) + BUG(); + dev = &sh->dev[failed_num]; + set_bit(R5_LOCKED, &dev->flags); + set_bit(R5_Wantwrite, &dev->flags); + locked++; + set_bit(STRIPE_INSYNC, &sh->state); + set_bit(R5_Syncio, &dev->flags); + } + } + if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) { + md_done_sync(conf->mddev, STRIPE_SECTORS,1); + clear_bit(STRIPE_SYNCING, &sh->state); + } + + spin_unlock(&sh->lock); + + while ((bi=return_bi)) { + int bytes = bi->bi_size; + + return_bi = bi->bi_next; + bi->bi_next = NULL; + bi->bi_size = 0; + bi->bi_end_io(bi, bytes, 0); + } + for (i=disks; i-- ;) { + int rw; + struct bio *bi; + mdk_rdev_t *rdev; + if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) + rw = 1; + else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags)) + rw = 0; + else + continue; + + bi = &sh->dev[i].req; + + bi->bi_rw = rw; + if (rw) + bi->bi_end_io = raid5_end_write_request; + else + bi->bi_end_io = raid5_end_read_request; + + rcu_read_lock(); + rdev = conf->disks[i].rdev; + if (rdev && rdev->faulty) + rdev = NULL; + if (rdev) + atomic_inc(&rdev->nr_pending); + rcu_read_unlock(); + + if (rdev) { + if (test_bit(R5_Syncio, &sh->dev[i].flags)) + md_sync_acct(rdev->bdev, STRIPE_SECTORS); + + bi->bi_bdev = rdev->bdev; + PRINTK("for %llu schedule op %ld on disc %d\n", + (unsigned long long)sh->sector, bi->bi_rw, i); + atomic_inc(&sh->count); + bi->bi_sector = sh->sector + rdev->data_offset; + bi->bi_flags = 1 << BIO_UPTODATE; + bi->bi_vcnt = 1; + bi->bi_max_vecs = 1; + bi->bi_idx = 0; + bi->bi_io_vec = &sh->dev[i].vec; + bi->bi_io_vec[0].bv_len = STRIPE_SIZE; + bi->bi_io_vec[0].bv_offset = 0; + bi->bi_size = STRIPE_SIZE; + bi->bi_next = NULL; + generic_make_request(bi); + } else { + PRINTK("skip op %ld on disc %d for sector %llu\n", + bi->bi_rw, i, (unsigned long long)sh->sector); + clear_bit(R5_LOCKED, &sh->dev[i].flags); + set_bit(STRIPE_HANDLE, &sh->state); + } + } +} + +static inline void raid5_activate_delayed(raid5_conf_t *conf) +{ + if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) { + while (!list_empty(&conf->delayed_list)) { + struct list_head *l = conf->delayed_list.next; + struct stripe_head *sh; + sh = list_entry(l, struct stripe_head, lru); + list_del_init(l); + clear_bit(STRIPE_DELAYED, &sh->state); + if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) + atomic_inc(&conf->preread_active_stripes); + list_add_tail(&sh->lru, &conf->handle_list); + } + } +} + +static void unplug_slaves(mddev_t *mddev) +{ + raid5_conf_t *conf = mddev_to_conf(mddev); + int i; + + rcu_read_lock(); + for (i=0; i<mddev->raid_disks; i++) { + mdk_rdev_t *rdev = conf->disks[i].rdev; + if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) { + request_queue_t *r_queue = bdev_get_queue(rdev->bdev); + + atomic_inc(&rdev->nr_pending); + rcu_read_unlock(); + + if (r_queue->unplug_fn) + r_queue->unplug_fn(r_queue); + + rdev_dec_pending(rdev, mddev); + rcu_read_lock(); + } + } + rcu_read_unlock(); +} + +static void raid5_unplug_device(request_queue_t *q) +{ + mddev_t *mddev = q->queuedata; + raid5_conf_t *conf = mddev_to_conf(mddev); + unsigned long flags; + + spin_lock_irqsave(&conf->device_lock, flags); + + if (blk_remove_plug(q)) + raid5_activate_delayed(conf); + md_wakeup_thread(mddev->thread); + + spin_unlock_irqrestore(&conf->device_lock, flags); + + unplug_slaves(mddev); +} + +static int raid5_issue_flush(request_queue_t *q, struct gendisk *disk, + sector_t *error_sector) +{ + mddev_t *mddev = q->queuedata; + raid5_conf_t *conf = mddev_to_conf(mddev); + int i, ret = 0; + + rcu_read_lock(); + for (i=0; i<mddev->raid_disks && ret == 0; i++) { + mdk_rdev_t *rdev = conf->disks[i].rdev; + if (rdev && !rdev->faulty) { + struct block_device *bdev = rdev->bdev; + request_queue_t *r_queue = bdev_get_queue(bdev); + + if (!r_queue->issue_flush_fn) + ret = -EOPNOTSUPP; + else { + atomic_inc(&rdev->nr_pending); + rcu_read_unlock(); + ret = r_queue->issue_flush_fn(r_queue, bdev->bd_disk, + error_sector); + rdev_dec_pending(rdev, mddev); + rcu_read_lock(); + } + } + } + rcu_read_unlock(); + return ret; +} + +static inline void raid5_plug_device(raid5_conf_t *conf) +{ + spin_lock_irq(&conf->device_lock); + blk_plug_device(conf->mddev->queue); + spin_unlock_irq(&conf->device_lock); +} + +static int make_request (request_queue_t *q, struct bio * bi) +{ + mddev_t *mddev = q->queuedata; + raid5_conf_t *conf = mddev_to_conf(mddev); + const unsigned int raid_disks = conf->raid_disks; + const unsigned int data_disks = raid_disks - 1; + unsigned int dd_idx, pd_idx; + sector_t new_sector; + sector_t logical_sector, last_sector; + struct stripe_head *sh; + + if (bio_data_dir(bi)==WRITE) { + disk_stat_inc(mddev->gendisk, writes); + disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bi)); + } else { + disk_stat_inc(mddev->gendisk, reads); + disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi)); + } + + logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1); + last_sector = bi->bi_sector + (bi->bi_size>>9); + bi->bi_next = NULL; + bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ + if ( bio_data_dir(bi) == WRITE ) + md_write_start(mddev); + for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { + DEFINE_WAIT(w); + + new_sector = raid5_compute_sector(logical_sector, + raid_disks, data_disks, &dd_idx, &pd_idx, conf); + + PRINTK("raid5: make_request, sector %llu logical %llu\n", + (unsigned long long)new_sector, + (unsigned long long)logical_sector); + + retry: + prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); + sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK)); + if (sh) { + if (!add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) { + /* Add failed due to overlap. Flush everything + * and wait a while + */ + raid5_unplug_device(mddev->queue); + release_stripe(sh); + schedule(); + goto retry; + } + finish_wait(&conf->wait_for_overlap, &w); + raid5_plug_device(conf); + handle_stripe(sh); + release_stripe(sh); + + } else { + /* cannot get stripe for read-ahead, just give-up */ + clear_bit(BIO_UPTODATE, &bi->bi_flags); + finish_wait(&conf->wait_for_overlap, &w); + break; + } + + } + spin_lock_irq(&conf->device_lock); + if (--bi->bi_phys_segments == 0) { + int bytes = bi->bi_size; + + if ( bio_data_dir(bi) == WRITE ) + md_write_end(mddev); + bi->bi_size = 0; + bi->bi_end_io(bi, bytes, 0); + } + spin_unlock_irq(&conf->device_lock); + return 0; +} + +/* FIXME go_faster isn't used */ +static int sync_request (mddev_t *mddev, sector_t sector_nr, int go_faster) +{ + raid5_conf_t *conf = (raid5_conf_t *) mddev->private; + struct stripe_head *sh; + int sectors_per_chunk = conf->chunk_size >> 9; + sector_t x; + unsigned long stripe; + int chunk_offset; + int dd_idx, pd_idx; + sector_t first_sector; + int raid_disks = conf->raid_disks; + int data_disks = raid_disks-1; + + if (sector_nr >= mddev->size <<1) { + /* just being told to finish up .. nothing much to do */ + unplug_slaves(mddev); + return 0; + } + /* if there is 1 or more failed drives and we are trying + * to resync, then assert that we are finished, because there is + * nothing we can do. + */ + if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) { + int rv = (mddev->size << 1) - sector_nr; + md_done_sync(mddev, rv, 1); + return rv; + } + + x = sector_nr; + chunk_offset = sector_div(x, sectors_per_chunk); + stripe = x; + BUG_ON(x != stripe); + + first_sector = raid5_compute_sector((sector_t)stripe*data_disks*sectors_per_chunk + + chunk_offset, raid_disks, data_disks, &dd_idx, &pd_idx, conf); + sh = get_active_stripe(conf, sector_nr, pd_idx, 1); + if (sh == NULL) { + sh = get_active_stripe(conf, sector_nr, pd_idx, 0); + /* make sure we don't swamp the stripe cache if someone else + * is trying to get access + */ + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_timeout(1); + } + spin_lock(&sh->lock); + set_bit(STRIPE_SYNCING, &sh->state); + clear_bit(STRIPE_INSYNC, &sh->state); + spin_unlock(&sh->lock); + + handle_stripe(sh); + release_stripe(sh); + + return STRIPE_SECTORS; +} + +/* + * This is our raid5 kernel thread. + * + * We scan the hash table for stripes which can be handled now. + * During the scan, completed stripes are saved for us by the interrupt + * handler, so that they will not have to wait for our next wakeup. + */ +static void raid5d (mddev_t *mddev) +{ + struct stripe_head *sh; + raid5_conf_t *conf = mddev_to_conf(mddev); + int handled; + + PRINTK("+++ raid5d active\n"); + + md_check_recovery(mddev); + md_handle_safemode(mddev); + + handled = 0; + spin_lock_irq(&conf->device_lock); + while (1) { + struct list_head *first; + + if (list_empty(&conf->handle_list) && + atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD && + !blk_queue_plugged(mddev->queue) && + !list_empty(&conf->delayed_list)) + raid5_activate_delayed(conf); + + if (list_empty(&conf->handle_list)) + break; + + first = conf->handle_list.next; + sh = list_entry(first, struct stripe_head, lru); + + list_del_init(first); + atomic_inc(&sh->count); + if (atomic_read(&sh->count)!= 1) + BUG(); + spin_unlock_irq(&conf->device_lock); + + handled++; + handle_stripe(sh); + release_stripe(sh); + + spin_lock_irq(&conf->device_lock); + } + PRINTK("%d stripes handled\n", handled); + + spin_unlock_irq(&conf->device_lock); + + unplug_slaves(mddev); + + PRINTK("--- raid5d inactive\n"); +} + +static int run (mddev_t *mddev) +{ + raid5_conf_t *conf; + int raid_disk, memory; + mdk_rdev_t *rdev; + struct disk_info *disk; + struct list_head *tmp; + + if (mddev->level != 5 && mddev->level != 4) { + printk("raid5: %s: raid level not set to 4/5 (%d)\n", mdname(mddev), mddev->level); + return -EIO; + } + + mddev->private = kmalloc (sizeof (raid5_conf_t) + + mddev->raid_disks * sizeof(struct disk_info), + GFP_KERNEL); + if ((conf = mddev->private) == NULL) + goto abort; + memset (conf, 0, sizeof (*conf) + mddev->raid_disks * sizeof(struct disk_info) ); + conf->mddev = mddev; + + if ((conf->stripe_hashtbl = (struct stripe_head **) __get_free_pages(GFP_ATOMIC, HASH_PAGES_ORDER)) == NULL) + goto abort; + memset(conf->stripe_hashtbl, 0, HASH_PAGES * PAGE_SIZE); + + spin_lock_init(&conf->device_lock); + init_waitqueue_head(&conf->wait_for_stripe); + init_waitqueue_head(&conf->wait_for_overlap); + INIT_LIST_HEAD(&conf->handle_list); + INIT_LIST_HEAD(&conf->delayed_list); + INIT_LIST_HEAD(&conf->inactive_list); + atomic_set(&conf->active_stripes, 0); + atomic_set(&conf->preread_active_stripes, 0); + + mddev->queue->unplug_fn = raid5_unplug_device; + mddev->queue->issue_flush_fn = raid5_issue_flush; + + PRINTK("raid5: run(%s) called.\n", mdname(mddev)); + + ITERATE_RDEV(mddev,rdev,tmp) { + raid_disk = rdev->raid_disk; + if (raid_disk >= mddev->raid_disks + || raid_disk < 0) + continue; + disk = conf->disks + raid_disk; + + disk->rdev = rdev; + + if (rdev->in_sync) { + char b[BDEVNAME_SIZE]; + printk(KERN_INFO "raid5: device %s operational as raid" + " disk %d\n", bdevname(rdev->bdev,b), + raid_disk); + conf->working_disks++; + } + } + + conf->raid_disks = mddev->raid_disks; + /* + * 0 for a fully functional array, 1 for a degraded array. + */ + mddev->degraded = conf->failed_disks = conf->raid_disks - conf->working_disks; + conf->mddev = mddev; + conf->chunk_size = mddev->chunk_size; + conf->level = mddev->level; + conf->algorithm = mddev->layout; + conf->max_nr_stripes = NR_STRIPES; + + /* device size must be a multiple of chunk size */ + mddev->size &= ~(mddev->chunk_size/1024 -1); + + if (!conf->chunk_size || conf->chunk_size % 4) { + printk(KERN_ERR "raid5: invalid chunk size %d for %s\n", + conf->chunk_size, mdname(mddev)); + goto abort; + } + if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) { + printk(KERN_ERR + "raid5: unsupported parity algorithm %d for %s\n", + conf->algorithm, mdname(mddev)); + goto abort; + } + if (mddev->degraded > 1) { + printk(KERN_ERR "raid5: not enough operational devices for %s" + " (%d/%d failed)\n", + mdname(mddev), conf->failed_disks, conf->raid_disks); + goto abort; + } + + if (mddev->degraded == 1 && + mddev->recovery_cp != MaxSector) { + printk(KERN_ERR + "raid5: cannot start dirty degraded array for %s\n", + mdname(mddev)); + goto abort; + } + + { + mddev->thread = md_register_thread(raid5d, mddev, "%s_raid5"); + if (!mddev->thread) { + printk(KERN_ERR + "raid5: couldn't allocate thread for %s\n", + mdname(mddev)); + goto abort; + } + } +memory = conf->max_nr_stripes * (sizeof(struct stripe_head) + + conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024; + if (grow_stripes(conf, conf->max_nr_stripes)) { + printk(KERN_ERR + "raid5: couldn't allocate %dkB for buffers\n", memory); + shrink_stripes(conf); + md_unregister_thread(mddev->thread); + goto abort; + } else + printk(KERN_INFO "raid5: allocated %dkB for %s\n", + memory, mdname(mddev)); + + if (mddev->degraded == 0) + printk("raid5: raid level %d set %s active with %d out of %d" + " devices, algorithm %d\n", conf->level, mdname(mddev), + mddev->raid_disks-mddev->degraded, mddev->raid_disks, + conf->algorithm); + else + printk(KERN_ALERT "raid5: raid level %d set %s active with %d" + " out of %d devices, algorithm %d\n", conf->level, + mdname(mddev), mddev->raid_disks - mddev->degraded, + mddev->raid_disks, conf->algorithm); + + print_raid5_conf(conf); + + /* read-ahead size must cover two whole stripes, which is + * 2 * (n-1) * chunksize where 'n' is the number of raid devices + */ + { + int stripe = (mddev->raid_disks-1) * mddev->chunk_size + / PAGE_CACHE_SIZE; + if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe) + mddev->queue->backing_dev_info.ra_pages = 2 * stripe; + } + + /* Ok, everything is just fine now */ + mddev->array_size = mddev->size * (mddev->raid_disks - 1); + return 0; +abort: + if (conf) { + print_raid5_conf(conf); + if (conf->stripe_hashtbl) + free_pages((unsigned long) conf->stripe_hashtbl, + HASH_PAGES_ORDER); + kfree(conf); + } + mddev->private = NULL; + printk(KERN_ALERT "raid5: failed to run raid set %s\n", mdname(mddev)); + return -EIO; +} + + + +static int stop (mddev_t *mddev) +{ + raid5_conf_t *conf = (raid5_conf_t *) mddev->private; + + md_unregister_thread(mddev->thread); + mddev->thread = NULL; + shrink_stripes(conf); + free_pages((unsigned long) conf->stripe_hashtbl, HASH_PAGES_ORDER); + blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ + kfree(conf); + mddev->private = NULL; + return 0; +} + +#if RAID5_DEBUG +static void print_sh (struct stripe_head *sh) +{ + int i; + + printk("sh %llu, pd_idx %d, state %ld.\n", + (unsigned long long)sh->sector, sh->pd_idx, sh->state); + printk("sh %llu, count %d.\n", + (unsigned long long)sh->sector, atomic_read(&sh->count)); + printk("sh %llu, ", (unsigned long long)sh->sector); + for (i = 0; i < sh->raid_conf->raid_disks; i++) { + printk("(cache%d: %p %ld) ", + i, sh->dev[i].page, sh->dev[i].flags); + } + printk("\n"); +} + +static void printall (raid5_conf_t *conf) +{ + struct stripe_head *sh; + int i; + + spin_lock_irq(&conf->device_lock); + for (i = 0; i < NR_HASH; i++) { + sh = conf->stripe_hashtbl[i]; + for (; sh; sh = sh->hash_next) { + if (sh->raid_conf != conf) + continue; + print_sh(sh); + } + } + spin_unlock_irq(&conf->device_lock); +} +#endif + +static void status (struct seq_file *seq, mddev_t *mddev) +{ + raid5_conf_t *conf = (raid5_conf_t *) mddev->private; + int i; + + seq_printf (seq, " level %d, %dk chunk, algorithm %d", mddev->level, mddev->chunk_size >> 10, mddev->layout); + seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->working_disks); + for (i = 0; i < conf->raid_disks; i++) + seq_printf (seq, "%s", + conf->disks[i].rdev && + conf->disks[i].rdev->in_sync ? "U" : "_"); + seq_printf (seq, "]"); +#if RAID5_DEBUG +#define D(x) \ + seq_printf (seq, "<"#x":%d>", atomic_read(&conf->x)) + printall(conf); +#endif +} + +static void print_raid5_conf (raid5_conf_t *conf) +{ + int i; + struct disk_info *tmp; + + printk("RAID5 conf printout:\n"); + if (!conf) { + printk("(conf==NULL)\n"); + return; + } + printk(" --- rd:%d wd:%d fd:%d\n", conf->raid_disks, + conf->working_disks, conf->failed_disks); + + for (i = 0; i < conf->raid_disks; i++) { + char b[BDEVNAME_SIZE]; + tmp = conf->disks + i; + if (tmp->rdev) + printk(" disk %d, o:%d, dev:%s\n", + i, !tmp->rdev->faulty, + bdevname(tmp->rdev->bdev,b)); + } +} + +static int raid5_spare_active(mddev_t *mddev) +{ + int i; + raid5_conf_t *conf = mddev->private; + struct disk_info *tmp; + + for (i = 0; i < conf->raid_disks; i++) { + tmp = conf->disks + i; + if (tmp->rdev + && !tmp->rdev->faulty + && !tmp->rdev->in_sync) { + mddev->degraded--; + conf->failed_disks--; + conf->working_disks++; + tmp->rdev->in_sync = 1; + } + } + print_raid5_conf(conf); + return 0; +} + +static int raid5_remove_disk(mddev_t *mddev, int number) +{ + raid5_conf_t *conf = mddev->private; + int err = 0; + mdk_rdev_t *rdev; + struct disk_info *p = conf->disks + number; + + print_raid5_conf(conf); + rdev = p->rdev; + if (rdev) { + if (rdev->in_sync || + atomic_read(&rdev->nr_pending)) { + err = -EBUSY; + goto abort; + } + p->rdev = NULL; + synchronize_kernel(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + p->rdev = rdev; + } + } +abort: + + print_raid5_conf(conf); + return err; +} + +static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) +{ + raid5_conf_t *conf = mddev->private; + int found = 0; + int disk; + struct disk_info *p; + + if (mddev->degraded > 1) + /* no point adding a device */ + return 0; + + /* + * find the disk ... + */ + for (disk=0; disk < mddev->raid_disks; disk++) + if ((p=conf->disks + disk)->rdev == NULL) { + rdev->in_sync = 0; + rdev->raid_disk = disk; + found = 1; + p->rdev = rdev; + break; + } + print_raid5_conf(conf); + return found; +} + +static int raid5_resize(mddev_t *mddev, sector_t sectors) +{ + /* no resync is happening, and there is enough space + * on all devices, so we can resize. + * We need to make sure resync covers any new space. + * If the array is shrinking we should possibly wait until + * any io in the removed space completes, but it hardly seems + * worth it. + */ + sectors &= ~((sector_t)mddev->chunk_size/512 - 1); + mddev->array_size = (sectors * (mddev->raid_disks-1))>>1; + set_capacity(mddev->gendisk, mddev->array_size << 1); + mddev->changed = 1; + if (sectors/2 > mddev->size && mddev->recovery_cp == MaxSector) { + mddev->recovery_cp = mddev->size << 1; + set_bit(MD_RECOVERY_NEEDED, &mddev->recovery); + } + mddev->size = sectors /2; + return 0; +} + +static mdk_personality_t raid5_personality= +{ + .name = "raid5", + .owner = THIS_MODULE, + .make_request = make_request, + .run = run, + .stop = stop, + .status = status, + .error_handler = error, + .hot_add_disk = raid5_add_disk, + .hot_remove_disk= raid5_remove_disk, + .spare_active = raid5_spare_active, + .sync_request = sync_request, + .resize = raid5_resize, +}; + +static int __init raid5_init (void) +{ + return register_md_personality (RAID5, &raid5_personality); +} + +static void raid5_exit (void) +{ + unregister_md_personality (RAID5); +} + +module_init(raid5_init); +module_exit(raid5_exit); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("md-personality-4"); /* RAID5 */ |
