| /* |
| * 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 (md_write_start(mddev, bi)==0) |
| return 0; |
| |
| 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 */ |
| |
| 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 sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, 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)) { |
| sector_t rv = (mddev->size << 1) - sector_nr; |
| *skipped = 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); |
| |
| 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); |
| |
| 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->queue->unplug_fn = raid5_unplug_device; |
| mddev->queue->issue_flush_fn = raid5_issue_flush; |
| |
| 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_rcu(); |
| 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 */ |