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linux/drivers/md/raid6main.c
NeilBrown 3d310eb7b3 [PATCH] md: fix deadlock due to md thread processing delayed requests. 
Before completing a 'write' the md superblock might need to be updated.
This is best done by the md_thread.

The current code schedules this up and queues the write request for later
handling by the md_thread.

However some personalities (Raid5/raid6) will deadlock if the md_thread
tries to submit requests to its own array.

So this patch changes things so the processes submitting the request waits
for the superblock to be written and then submits the request itself.

This fixes a recently-created deadlock in raid5/raid6

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:46 -07:00

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/*
* raid6main.c : Multiple Devices driver for Linux
* Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
* Copyright (C) 1999, 2000 Ingo Molnar
* Copyright (C) 2002, 2003 H. Peter Anvin
*
* RAID-6 management functions. This code is derived from raid5.c.
* Last merge from raid5.c bkcvs version 1.79 (kernel 2.6.1).
*
* Thanks to Penguin Computing for making the RAID-6 development possible
* by donating a test server!
*
* 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/highmem.h>
#include <linux/bitops.h>
#include <asm/atomic.h>
#include "raid6.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 RAID6_DEBUG 0 /* Extremely verbose printk */
#define RAID6_PARANOIA 1 /* Check spinlocks */
#define RAID6_DUMPSTATE 0 /* Include stripe cache state in /proc/mdstat */
#if RAID6_PARANOIA && defined(CONFIG_SMP)
# define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
#else
# define CHECK_DEVLOCK()
#endif
#define PRINTK(x...) ((void)(RAID6_DEBUG && printk(KERN_DEBUG x)))
#if RAID6_DEBUG
#undef inline
#undef __inline__
#define inline
#define __inline__
#endif
#if !RAID6_USE_EMPTY_ZERO_PAGE
/* In .bss so it's zeroed */
const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
#endif
static inline int raid6_next_disk(int disk, int raid_disks)
{
disk++;
return (disk < raid_disks) ? disk : 0;
}
static void print_raid6_conf (raid6_conf_t *conf);
static inline void __release_stripe(raid6_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)
{
raid6_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(raid6_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(raid6_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 raid6_build_block (struct stripe_head *sh, int i);
static inline void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx)
{
raid6_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;
raid6_build_block(sh, i);
}
insert_hash(conf, sh);
}
static struct stripe_head *__find_stripe(raid6_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 struct stripe_head *get_active_stripe(raid6_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(raid6_conf_t *conf, int num)
{
struct stripe_head *sh;
kmem_cache_t *sc;
int devs = conf->raid_disks;
sprintf(conf->cache_name, "raid6/%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(raid6_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 raid6_end_read_request (struct bio * bi, unsigned int bytes_done,
int error)
{
struct stripe_head *sh = bi->bi_private;
raid6_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 raid6_end_write_request (struct bio *bi, unsigned int bytes_done,
int error)
{
struct stripe_head *sh = bi->bi_private;
raid6_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 raid6_build_block (struct stripe_head *sh, int i)
{
struct r5dev *dev = &sh->dev[i];
int pd_idx = sh->pd_idx;
int qd_idx = raid6_next_disk(pd_idx, sh->raid_conf->raid_disks);
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 != pd_idx && i != qd_idx)
dev->sector = compute_blocknr(sh, i);
}
static void error(mddev_t *mddev, mdk_rdev_t *rdev)
{
char b[BDEVNAME_SIZE];
raid6_conf_t *conf = (raid6_conf_t *) mddev->private;
PRINTK("raid6: 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
"raid6: 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 raid6_compute_sector(sector_t r_sector, unsigned int raid_disks,
unsigned int data_disks, unsigned int * dd_idx,
unsigned int * pd_idx, raid6_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;
if ( r_sector != chunk_number ) {
printk(KERN_CRIT "raid6: ERROR: r_sector = %llu, chunk_number = %lu\n",
(unsigned long long)r_sector, (unsigned long)chunk_number);
BUG();
}
/*
* 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.
*/
/**** FIX THIS ****/
switch (conf->algorithm) {
case ALGORITHM_LEFT_ASYMMETRIC:
*pd_idx = raid_disks - 1 - (stripe % raid_disks);
if (*pd_idx == raid_disks-1)
(*dd_idx)++; /* Q D D D P */
else if (*dd_idx >= *pd_idx)
(*dd_idx) += 2; /* D D P Q D */
break;
case ALGORITHM_RIGHT_ASYMMETRIC:
*pd_idx = stripe % raid_disks;
if (*pd_idx == raid_disks-1)
(*dd_idx)++; /* Q D D D P */
else if (*dd_idx >= *pd_idx)
(*dd_idx) += 2; /* D D P Q D */
break;
case ALGORITHM_LEFT_SYMMETRIC:
*pd_idx = raid_disks - 1 - (stripe % raid_disks);
*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
break;
case ALGORITHM_RIGHT_SYMMETRIC:
*pd_idx = stripe % raid_disks;
*dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
break;
default:
printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
conf->algorithm);
}
PRINTK("raid6: chunk_number = %lu, pd_idx = %u, dd_idx = %u\n",
chunk_number, *pd_idx, *dd_idx);
/*
* 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)
{
raid6_conf_t *conf = sh->raid_conf;
int raid_disks = conf->raid_disks, data_disks = raid_disks - 2;
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;
int i0 = i;
chunk_offset = sector_div(new_sector, sectors_per_chunk);
stripe = new_sector;
if ( new_sector != stripe ) {
printk(KERN_CRIT "raid6: ERROR: new_sector = %llu, stripe = %lu\n",
(unsigned long long)new_sector, (unsigned long)stripe);
BUG();
}
switch (conf->algorithm) {
case ALGORITHM_LEFT_ASYMMETRIC:
case ALGORITHM_RIGHT_ASYMMETRIC:
if (sh->pd_idx == raid_disks-1)
i--; /* Q D D D P */
else if (i > sh->pd_idx)
i -= 2; /* D D P Q D */
break;
case ALGORITHM_LEFT_SYMMETRIC:
case ALGORITHM_RIGHT_SYMMETRIC:
if (sh->pd_idx == raid_disks-1)
i--; /* Q D D D P */
else {
/* D D P Q D */
if (i < sh->pd_idx)
i += raid_disks;
i -= (sh->pd_idx + 2);
}
break;
default:
printk (KERN_CRIT "raid6: unsupported algorithm %d\n",
conf->algorithm);
}
PRINTK("raid6: compute_blocknr: pd_idx = %u, i0 = %u, i = %u\n", sh->pd_idx, i0, i);
chunk_number = stripe * data_disks + i;
r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
check = raid6_compute_sector (r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
printk(KERN_CRIT "raid6: compute_blocknr: map not correct\n");
return 0;
}
return r_sector;
}
/*
* Copy data between a page in the stripe cache, and one or more bion
* The page could align with the middle of the bio, or there could be
* several bion, each with several bio_vecs, which cover part of the page
* Multiple bion are linked together on bi_next. There may be extras
* at the end of this list. We ignore them.
*/
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)
/* Compute P and Q syndromes */
static void compute_parity(struct stripe_head *sh, int method)
{
raid6_conf_t *conf = sh->raid_conf;
int i, pd_idx = sh->pd_idx, qd_idx, d0_idx, disks = conf->raid_disks, count;
struct bio *chosen;
/**** FIX THIS: This could be very bad if disks is close to 256 ****/
void *ptrs[disks];
qd_idx = raid6_next_disk(pd_idx, disks);
d0_idx = raid6_next_disk(qd_idx, disks);
PRINTK("compute_parity, stripe %llu, method %d\n",
(unsigned long long)sh->sector, method);
switch(method) {
case READ_MODIFY_WRITE:
BUG(); /* READ_MODIFY_WRITE N/A for RAID-6 */
case RECONSTRUCT_WRITE:
for (i= disks; i-- ;)
if ( i != pd_idx && i != qd_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:
BUG(); /* Not implemented yet */
}
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:
// case UPDATE_PARITY:
/* Note that unlike RAID-5, the ordering of the disks matters greatly. */
/* FIX: Is this ordering of drives even remotely optimal? */
count = 0;
i = d0_idx;
do {
ptrs[count++] = page_address(sh->dev[i].page);
if (count <= disks-2 && !test_bit(R5_UPTODATE, &sh->dev[i].flags))
printk("block %d/%d not uptodate on parity calc\n", i,count);
i = raid6_next_disk(i, disks);
} while ( i != d0_idx );
// break;
// }
raid6_call.gen_syndrome(disks, STRIPE_SIZE, ptrs);
switch(method) {
case RECONSTRUCT_WRITE:
set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
set_bit(R5_LOCKED, &sh->dev[qd_idx].flags);
break;
case UPDATE_PARITY:
set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
set_bit(R5_UPTODATE, &sh->dev[qd_idx].flags);
break;
}
}
/* Compute one missing block */
static void compute_block_1(struct stripe_head *sh, int dd_idx)
{
raid6_conf_t *conf = sh->raid_conf;
int i, count, disks = conf->raid_disks;
void *ptr[MAX_XOR_BLOCKS], *p;
int pd_idx = sh->pd_idx;
int qd_idx = raid6_next_disk(pd_idx, disks);
PRINTK("compute_block_1, stripe %llu, idx %d\n",
(unsigned long long)sh->sector, dd_idx);
if ( dd_idx == qd_idx ) {
/* We're actually computing the Q drive */
compute_parity(sh, UPDATE_PARITY);
} else {
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 || i == qd_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);
}
}
/* Compute two missing blocks */
static void compute_block_2(struct stripe_head *sh, int dd_idx1, int dd_idx2)
{
raid6_conf_t *conf = sh->raid_conf;
int i, count, disks = conf->raid_disks;
int pd_idx = sh->pd_idx;
int qd_idx = raid6_next_disk(pd_idx, disks);
int d0_idx = raid6_next_disk(qd_idx, disks);
int faila, failb;
/* faila and failb are disk numbers relative to d0_idx */
/* pd_idx become disks-2 and qd_idx become disks-1 */
faila = (dd_idx1 < d0_idx) ? dd_idx1+(disks-d0_idx) : dd_idx1-d0_idx;
failb = (dd_idx2 < d0_idx) ? dd_idx2+(disks-d0_idx) : dd_idx2-d0_idx;
BUG_ON(faila == failb);
if ( failb < faila ) { int tmp = faila; faila = failb; failb = tmp; }
PRINTK("compute_block_2, stripe %llu, idx %d,%d (%d,%d)\n",
(unsigned long long)sh->sector, dd_idx1, dd_idx2, faila, failb);
if ( failb == disks-1 ) {
/* Q disk is one of the missing disks */
if ( faila == disks-2 ) {
/* Missing P+Q, just recompute */
compute_parity(sh, UPDATE_PARITY);
return;
} else {
/* We're missing D+Q; recompute D from P */
compute_block_1(sh, (dd_idx1 == qd_idx) ? dd_idx2 : dd_idx1);
compute_parity(sh, UPDATE_PARITY); /* Is this necessary? */
return;
}
}
/* We're missing D+P or D+D; build pointer table */
{
/**** FIX THIS: This could be very bad if disks is close to 256 ****/
void *ptrs[disks];
count = 0;
i = d0_idx;
do {
ptrs[count++] = page_address(sh->dev[i].page);
i = raid6_next_disk(i, disks);
if (i != dd_idx1 && i != dd_idx2 &&
!test_bit(R5_UPTODATE, &sh->dev[i].flags))
printk("compute_2 with missing block %d/%d\n", count, i);
} while ( i != d0_idx );
if ( failb == disks-2 ) {
/* We're missing D+P. */
raid6_datap_recov(disks, STRIPE_SIZE, faila, ptrs);
} else {
/* We're missing D+D. */
raid6_2data_recov(disks, STRIPE_SIZE, faila, failb, ptrs);
}
/* Both the above update both missing blocks */
set_bit(R5_UPTODATE, &sh->dev[dd_idx1].flags);
set_bit(R5_UPTODATE, &sh->dev[dd_idx2].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;
raid6_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)
{
raid6_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[2] = {0, 0};
struct r5dev *dev, *pdev, *qdev;
int pd_idx = sh->pd_idx;
int qd_idx = raid6_next_disk(pd_idx, disks);
int p_failed, q_failed;
PRINTK("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d, qd_idx=%d\n",
(unsigned long long)sh->sector, sh->state, atomic_read(&sh->count),
pd_idx, qd_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) {
if ( failed < 2 )
failed_num[failed] = i;
failed++;
} else
set_bit(R5_Insync, &dev->flags);
}
PRINTK("locked=%d uptodate=%d to_read=%d"
" to_write=%d failed=%d failed_num=%d,%d\n",
locked, uptodate, to_read, to_write, failed,
failed_num[0], failed_num[1]);
/* check if the array has lost >2 devices and, if so, some requests might
* need to be failed
*/
if (failed > 2 && 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 > 2 && 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 blocks
* are safe, or on a failed drive
*/
pdev = &sh->dev[pd_idx];
p_failed = (failed >= 1 && failed_num[0] == pd_idx)
|| (failed >= 2 && failed_num[1] == pd_idx);
qdev = &sh->dev[qd_idx];
q_failed = (failed >= 1 && failed_num[0] == qd_idx)
|| (failed >= 2 && failed_num[1] == qd_idx);
if ( written &&
( p_failed || ((test_bit(R5_Insync, &pdev->flags)
&& !test_bit(R5_LOCKED, &pdev->flags)
&& test_bit(R5_UPTODATE, &pdev->flags))) ) &&
( q_failed || ((test_bit(R5_Insync, &qdev->flags)
&& !test_bit(R5_LOCKED, &qdev->flags)
&& test_bit(R5_UPTODATE, &qdev->flags))) ) ) {
/* 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 stripe %llu disc %d\n",
(unsigned long long)sh->sector, 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 || (to_write && failed) || (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 >= 1 && (sh->dev[failed_num[0]].toread || to_write)) ||
(failed >= 2 && (sh->dev[failed_num[1]].toread || to_write))
)
) {
/* we would like to get this block, possibly
* by computing it, but we might not be able to
*/
if (uptodate == disks-1) {
PRINTK("Computing stripe %llu block %d\n",
(unsigned long long)sh->sector, i);
compute_block_1(sh, i);
uptodate++;
} else if ( uptodate == disks-2 && failed >= 2 ) {
/* Computing 2-failure is *very* expensive; only do it if failed >= 2 */
int other;
for (other=disks; other--;) {
if ( other == i )
continue;
if ( !test_bit(R5_UPTODATE, &sh->dev[other].flags) )
break;
}
BUG_ON(other < 0);
PRINTK("Computing stripe %llu blocks %d,%d\n",
(unsigned long long)sh->sector, i, other);
compute_block_2(sh, i, other);
uptodate += 2;
} 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 rcw=0, must_compute=0;
for (i=disks ; i--;) {
dev = &sh->dev[i];
/* Would I have to read this buffer for reconstruct_write */
if (!test_bit(R5_OVERWRITE, &dev->flags)
&& i != pd_idx && i != qd_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 {
PRINTK("raid6: must_compute: disk %d flags=%#lx\n", i, dev->flags);
must_compute++;
}
}
}
PRINTK("for sector %llu, rcw=%d, must_compute=%d\n",
(unsigned long long)sh->sector, rcw, must_compute);
set_bit(STRIPE_HANDLE, &sh->state);
if (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)
&& !(failed == 0 && (i == pd_idx || i == qd_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 stripe %llu block %d for Reconstruct\n",
(unsigned long long)sh->sector, i);
set_bit(R5_LOCKED, &dev->flags);
set_bit(R5_Wantread, &dev->flags);
locked++;
} else {
PRINTK("Request delayed stripe %llu block %d for Reconstruct\n",
(unsigned long long)sh->sector, i);
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) {
if ( must_compute > 0 ) {
/* We have failed blocks and need to compute them */
switch ( failed ) {
case 0: BUG();
case 1: compute_block_1(sh, failed_num[0]); break;
case 2: compute_block_2(sh, failed_num[0], failed_num[1]); break;
default: BUG(); /* This request should have been failed? */
}
}
PRINTK("Computing parity for stripe %llu\n", (unsigned long long)sh->sector);
compute_parity(sh, RECONSTRUCT_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 stripe %llu block %d\n",
(unsigned long long)sh->sector, i);
locked++;
set_bit(R5_Wantwrite, &sh->dev[i].flags);
#if 0 /**** FIX: I don't understand the logic here... ****/
if (!test_bit(R5_Insync, &sh->dev[i].flags)
|| ((i==pd_idx || i==qd_idx) && failed == 0)) /* FIX? */
set_bit(STRIPE_INSYNC, &sh->state);
#endif
}
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 <= 2) {
set_bit(STRIPE_HANDLE, &sh->state);
#if 0 /* RAID-6: Don't support CHECK PARITY yet */
if (failed == 0) {
char *pagea;
if (uptodate != disks)
BUG();
compute_parity(sh, CHECK_PARITY);
uptodate--;
pagea = page_address(sh->dev[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);
}
}
#endif
if (!test_bit(STRIPE_INSYNC, &sh->state)) {
int failed_needupdate[2];
struct r5dev *adev, *bdev;
if ( failed < 1 )
failed_num[0] = pd_idx;
if ( failed < 2 )
failed_num[1] = (failed_num[0] == qd_idx) ? pd_idx : qd_idx;
failed_needupdate[0] = !test_bit(R5_UPTODATE, &sh->dev[failed_num[0]].flags);
failed_needupdate[1] = !test_bit(R5_UPTODATE, &sh->dev[failed_num[1]].flags);
PRINTK("sync: failed=%d num=%d,%d fnu=%u%u\n",
failed, failed_num[0], failed_num[1], failed_needupdate[0], failed_needupdate[1]);
#if 0 /* RAID-6: This code seems to require that CHECK_PARITY destroys the uptodateness of the parity */
/* should be able to compute the missing block(s) and write to spare */
if ( failed_needupdate[0] ^ failed_needupdate[1] ) {
if (uptodate+1 != disks)
BUG();
compute_block_1(sh, failed_needupdate[0] ? failed_num[0] : failed_num[1]);
uptodate++;
} else if ( failed_needupdate[0] & failed_needupdate[1] ) {
if (uptodate+2 != disks)
BUG();
compute_block_2(sh, failed_num[0], failed_num[1]);
uptodate += 2;
}
#else
compute_block_2(sh, failed_num[0], failed_num[1]);
uptodate += failed_needupdate[0] + failed_needupdate[1];
#endif
if (uptodate != disks)
BUG();
PRINTK("Marking for sync stripe %llu blocks %d,%d\n",
(unsigned long long)sh->sector, failed_num[0], failed_num[1]);
/**** FIX: Should we really do both of these unconditionally? ****/
adev = &sh->dev[failed_num[0]];
locked += !test_bit(R5_LOCKED, &adev->flags);
set_bit(R5_LOCKED, &adev->flags);
set_bit(R5_Wantwrite, &adev->flags);
bdev = &sh->dev[failed_num[1]];
locked += !test_bit(R5_LOCKED, &bdev->flags);
set_bit(R5_LOCKED, &bdev->flags);
set_bit(R5_Wantwrite, &bdev->flags);
set_bit(STRIPE_INSYNC, &sh->state);
set_bit(R5_Syncio, &adev->flags);
set_bit(R5_Syncio, &bdev->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 = raid6_end_write_request;
else
bi->bi_end_io = raid6_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 raid6_activate_delayed(raid6_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)
{
raid6_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 raid6_unplug_device(request_queue_t *q)
{
mddev_t *mddev = q->queuedata;
raid6_conf_t *conf = mddev_to_conf(mddev);
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
if (blk_remove_plug(q))
raid6_activate_delayed(conf);
md_wakeup_thread(mddev->thread);
spin_unlock_irqrestore(&conf->device_lock, flags);
unplug_slaves(mddev);
}
static int raid6_issue_flush(request_queue_t *q, struct gendisk *disk,
sector_t *error_sector)
{
mddev_t *mddev = q->queuedata;
raid6_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 raid6_plug_device(raid6_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;
raid6_conf_t *conf = mddev_to_conf(mddev);
const unsigned int raid_disks = conf->raid_disks;
const unsigned int data_disks = raid_disks - 2;
unsigned int dd_idx, pd_idx;
sector_t new_sector;
sector_t logical_sector, last_sector;
struct stripe_head *sh;
md_write_start(mddev, bi);
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 = raid6_compute_sector(logical_sector,
raid_disks, data_disks, &dd_idx, &pd_idx, conf);
PRINTK("raid6: 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
*/
raid6_unplug_device(mddev->queue);
release_stripe(sh);
schedule();
goto retry;
}
finish_wait(&conf->wait_for_overlap, &w);
raid6_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)
{
raid6_conf_t *conf = (raid6_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 - 2;
if (sector_nr >= mddev->size <<1) {
/* just being told to finish up .. nothing much to do */
unplug_slaves(mddev);
return 0;
}
/* if there are 2 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 >= 2 && 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 = raid6_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 raid6 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 raid6d (mddev_t *mddev)
{
struct stripe_head *sh;
raid6_conf_t *conf = mddev_to_conf(mddev);
int handled;
PRINTK("+++ raid6d 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))
raid6_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("--- raid6d inactive\n");
}
static int run (mddev_t *mddev)
{
raid6_conf_t *conf;
int raid_disk, memory;
mdk_rdev_t *rdev;
struct disk_info *disk;
struct list_head *tmp;
if (mddev->level != 6) {
PRINTK("raid6: %s: raid level not set to 6 (%d)\n", mdname(mddev), mddev->level);
return -EIO;
}
mddev->private = kmalloc (sizeof (raid6_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("raid6: 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 "raid6: 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 or 2 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->raid_disks < 4) {
printk(KERN_ERR "raid6: not enough configured devices for %s (%d, minimum 4)\n",
mdname(mddev), conf->raid_disks);
goto abort;
}
if (!conf->chunk_size || conf->chunk_size % 4) {
printk(KERN_ERR "raid6: invalid chunk size %d for %s\n",
conf->chunk_size, mdname(mddev));
goto abort;
}
if (conf->algorithm > ALGORITHM_RIGHT_SYMMETRIC) {
printk(KERN_ERR
"raid6: unsupported parity algorithm %d for %s\n",
conf->algorithm, mdname(mddev));
goto abort;
}
if (mddev->degraded > 2) {
printk(KERN_ERR "raid6: not enough operational devices for %s"
" (%d/%d failed)\n",
mdname(mddev), conf->failed_disks, conf->raid_disks);
goto abort;
}
#if 0 /* FIX: For now */
if (mddev->degraded > 0 &&
mddev->recovery_cp != MaxSector) {
printk(KERN_ERR "raid6: cannot start dirty degraded array for %s\n", mdname(mddev));
goto abort;
}
#endif
{
mddev->thread = md_register_thread(raid6d, mddev, "%s_raid6");
if (!mddev->thread) {
printk(KERN_ERR
"raid6: 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
"raid6: couldn't allocate %dkB for buffers\n", memory);
shrink_stripes(conf);
md_unregister_thread(mddev->thread);
goto abort;
} else
printk(KERN_INFO "raid6: allocated %dkB for %s\n",
memory, mdname(mddev));
if (mddev->degraded == 0)
printk(KERN_INFO "raid6: 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 "raid6: 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_raid6_conf(conf);
/* read-ahead size must cover two whole stripes, which is
* 2 * (n-2) * chunksize where 'n' is the number of raid devices
*/
{
int stripe = (mddev->raid_disks-2) * 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 - 2);
mddev->queue->unplug_fn = raid6_unplug_device;
mddev->queue->issue_flush_fn = raid6_issue_flush;
return 0;
abort:
if (conf) {
print_raid6_conf(conf);
if (conf->stripe_hashtbl)
free_pages((unsigned long) conf->stripe_hashtbl,
HASH_PAGES_ORDER);
kfree(conf);
}
mddev->private = NULL;
printk(KERN_ALERT "raid6: failed to run raid set %s\n", mdname(mddev));
return -EIO;
}
static int stop (mddev_t *mddev)
{
raid6_conf_t *conf = (raid6_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 RAID6_DUMPSTATE
static void print_sh (struct seq_file *seq, struct stripe_head *sh)
{
int i;
seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
(unsigned long long)sh->sector, sh->pd_idx, sh->state);
seq_printf(seq, "sh %llu, count %d.\n",
(unsigned long long)sh->sector, atomic_read(&sh->count));
seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
for (i = 0; i < sh->raid_conf->raid_disks; i++) {
seq_printf(seq, "(cache%d: %p %ld) ",
i, sh->dev[i].page, sh->dev[i].flags);
}
seq_printf(seq, "\n");
}
static void printall (struct seq_file *seq, raid6_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(seq, sh);
}
}
spin_unlock_irq(&conf->device_lock);
}
#endif
static void status (struct seq_file *seq, mddev_t *mddev)
{
raid6_conf_t *conf = (raid6_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 RAID6_DUMPSTATE
seq_printf (seq, "\n");
printall(seq, conf);
#endif
}
static void print_raid6_conf (raid6_conf_t *conf)
{
int i;
struct disk_info *tmp;
printk("RAID6 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 raid6_spare_active(mddev_t *mddev)
{
int i;
raid6_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_raid6_conf(conf);
return 0;
}
static int raid6_remove_disk(mddev_t *mddev, int number)
{
raid6_conf_t *conf = mddev->private;
int err = 0;
mdk_rdev_t *rdev;
struct disk_info *p = conf->disks + number;
print_raid6_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_raid6_conf(conf);
return err;
}
static int raid6_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
{
raid6_conf_t *conf = mddev->private;
int found = 0;
int disk;
struct disk_info *p;
if (mddev->degraded > 2)
/* 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_raid6_conf(conf);
return found;
}
static int raid6_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-2))>>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 raid6_personality=
{
.name = "raid6",
.owner = THIS_MODULE,
.make_request = make_request,
.run = run,
.stop = stop,
.status = status,
.error_handler = error,
.hot_add_disk = raid6_add_disk,
.hot_remove_disk= raid6_remove_disk,
.spare_active = raid6_spare_active,
.sync_request = sync_request,
.resize = raid6_resize,
};
static int __init raid6_init (void)
{
int e;
e = raid6_select_algo();
if ( e )
return e;
return register_md_personality (RAID6, &raid6_personality);
}
static void raid6_exit (void)
{
unregister_md_personality (RAID6);
}
module_init(raid6_init);
module_exit(raid6_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("md-personality-8"); /* RAID6 */
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