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md.c
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/*
md.c : Multiple Devices driver for Linux
Copyright (C) 1998, 1999, 2000 Ingo Molnar
completely rewritten, based on the MD driver code from Marc Zyngier
Changes:
- RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
- RAID-6 extensions by H. Peter Anvin <[email protected]>
- boot support for linear and striped mode by Harald Hoyer <[email protected]>
- kerneld support by Boris Tobotras <[email protected]>
- kmod support by: Cyrus Durgin
- RAID0 bugfixes: Mark Anthony Lisher <[email protected]>
- Devfs support by Richard Gooch <[email protected]>
- lots of fixes and improvements to the RAID1/RAID5 and generic
RAID code (such as request based resynchronization):
Neil Brown <[email protected]>.
- persistent bitmap code
Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
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/kthread.h>
#include <linux/blkdev.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/buffer_head.h> /* for invalidate_bdev */
#include <linux/poll.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/hdreg.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include <linux/reboot.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/delay.h>
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include <linux/slab.h>
#include "md.h"
#include "bitmap.h"
#define DEBUG 0
#define dprintk(x...) ((void)(DEBUG && printk(x)))
#ifndef MODULE
static void autostart_arrays(int part);
#endif
static LIST_HEAD(pers_list);
static DEFINE_SPINLOCK(pers_lock);
static void md_print_devices(void);
static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }
/*
* Default number of read corrections we'll attempt on an rdev
* before ejecting it from the array. We divide the read error
* count by 2 for every hour elapsed between read errors.
*/
#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
/*
* Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
* is 1000 KB/sec, so the extra system load does not show up that much.
* Increase it if you want to have more _guaranteed_ speed. Note that
* the RAID driver will use the maximum available bandwidth if the IO
* subsystem is idle. There is also an 'absolute maximum' reconstruction
* speed limit - in case reconstruction slows down your system despite
* idle IO detection.
*
* you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
* or /sys/block/mdX/md/sync_speed_{min,max}
*/
static int sysctl_speed_limit_min = 1000;
static int sysctl_speed_limit_max = 200000;
static inline int speed_min(mddev_t *mddev)
{
return mddev->sync_speed_min ?
mddev->sync_speed_min : sysctl_speed_limit_min;
}
static inline int speed_max(mddev_t *mddev)
{
return mddev->sync_speed_max ?
mddev->sync_speed_max : sysctl_speed_limit_max;
}
static struct ctl_table_header *raid_table_header;
static ctl_table raid_table[] = {
{
.procname = "speed_limit_min",
.data = &sysctl_speed_limit_min,
.maxlen = sizeof(int),
.mode = S_IRUGO|S_IWUSR,
.proc_handler = proc_dointvec,
},
{
.procname = "speed_limit_max",
.data = &sysctl_speed_limit_max,
.maxlen = sizeof(int),
.mode = S_IRUGO|S_IWUSR,
.proc_handler = proc_dointvec,
},
{ }
};
static ctl_table raid_dir_table[] = {
{
.procname = "raid",
.maxlen = 0,
.mode = S_IRUGO|S_IXUGO,
.child = raid_table,
},
{ }
};
static ctl_table raid_root_table[] = {
{
.procname = "dev",
.maxlen = 0,
.mode = 0555,
.child = raid_dir_table,
},
{ }
};
static const struct block_device_operations md_fops;
static int start_readonly;
/*
* We have a system wide 'event count' that is incremented
* on any 'interesting' event, and readers of /proc/mdstat
* can use 'poll' or 'select' to find out when the event
* count increases.
*
* Events are:
* start array, stop array, error, add device, remove device,
* start build, activate spare
*/
static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
static atomic_t md_event_count;
void md_new_event(mddev_t *mddev)
{
atomic_inc(&md_event_count);
wake_up(&md_event_waiters);
}
EXPORT_SYMBOL_GPL(md_new_event);
/* Alternate version that can be called from interrupts
* when calling sysfs_notify isn't needed.
*/
static void md_new_event_inintr(mddev_t *mddev)
{
atomic_inc(&md_event_count);
wake_up(&md_event_waiters);
}
/*
* Enables to iterate over all existing md arrays
* all_mddevs_lock protects this list.
*/
static LIST_HEAD(all_mddevs);
static DEFINE_SPINLOCK(all_mddevs_lock);
/*
* iterates through all used mddevs in the system.
* We take care to grab the all_mddevs_lock whenever navigating
* the list, and to always hold a refcount when unlocked.
* Any code which breaks out of this loop while own
* a reference to the current mddev and must mddev_put it.
*/
#define for_each_mddev(mddev,tmp) \
\
for (({ spin_lock(&all_mddevs_lock); \
tmp = all_mddevs.next; \
mddev = NULL;}); \
({ if (tmp != &all_mddevs) \
mddev_get(list_entry(tmp, mddev_t, all_mddevs));\
spin_unlock(&all_mddevs_lock); \
if (mddev) mddev_put(mddev); \
mddev = list_entry(tmp, mddev_t, all_mddevs); \
tmp != &all_mddevs;}); \
({ spin_lock(&all_mddevs_lock); \
tmp = tmp->next;}) \
)
/* Rather than calling directly into the personality make_request function,
* IO requests come here first so that we can check if the device is
* being suspended pending a reconfiguration.
* We hold a refcount over the call to ->make_request. By the time that
* call has finished, the bio has been linked into some internal structure
* and so is visible to ->quiesce(), so we don't need the refcount any more.
*/
static int md_make_request(struct request_queue *q, struct bio *bio)
{
const int rw = bio_data_dir(bio);
mddev_t *mddev = q->queuedata;
int rv;
int cpu;
if (mddev == NULL || mddev->pers == NULL) {
bio_io_error(bio);
return 0;
}
rcu_read_lock();
if (mddev->suspended || mddev->barrier) {
DEFINE_WAIT(__wait);
for (;;) {
prepare_to_wait(&mddev->sb_wait, &__wait,
TASK_UNINTERRUPTIBLE);
if (!mddev->suspended && !mddev->barrier)
break;
rcu_read_unlock();
schedule();
rcu_read_lock();
}
finish_wait(&mddev->sb_wait, &__wait);
}
atomic_inc(&mddev->active_io);
rcu_read_unlock();
rv = mddev->pers->make_request(mddev, bio);
cpu = part_stat_lock();
part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
bio_sectors(bio));
part_stat_unlock();
if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
wake_up(&mddev->sb_wait);
return rv;
}
/* mddev_suspend makes sure no new requests are submitted
* to the device, and that any requests that have been submitted
* are completely handled.
* Once ->stop is called and completes, the module will be completely
* unused.
*/
static void mddev_suspend(mddev_t *mddev)
{
BUG_ON(mddev->suspended);
mddev->suspended = 1;
synchronize_rcu();
wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
mddev->pers->quiesce(mddev, 1);
}
static void mddev_resume(mddev_t *mddev)
{
mddev->suspended = 0;
wake_up(&mddev->sb_wait);
mddev->pers->quiesce(mddev, 0);
}
int mddev_congested(mddev_t *mddev, int bits)
{
if (mddev->barrier)
return 1;
return mddev->suspended;
}
EXPORT_SYMBOL(mddev_congested);
/*
* Generic barrier handling for md
*/
#define POST_REQUEST_BARRIER ((void*)1)
static void md_end_barrier(struct bio *bio, int err)
{
mdk_rdev_t *rdev = bio->bi_private;
mddev_t *mddev = rdev->mddev;
if (err == -EOPNOTSUPP && mddev->barrier != POST_REQUEST_BARRIER)
set_bit(BIO_EOPNOTSUPP, &mddev->barrier->bi_flags);
rdev_dec_pending(rdev, mddev);
if (atomic_dec_and_test(&mddev->flush_pending)) {
if (mddev->barrier == POST_REQUEST_BARRIER) {
/* This was a post-request barrier */
mddev->barrier = NULL;
wake_up(&mddev->sb_wait);
} else
/* The pre-request barrier has finished */
schedule_work(&mddev->barrier_work);
}
bio_put(bio);
}
static void submit_barriers(mddev_t *mddev)
{
mdk_rdev_t *rdev;
rcu_read_lock();
list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
if (rdev->raid_disk >= 0 &&
!test_bit(Faulty, &rdev->flags)) {
/* Take two references, one is dropped
* when request finishes, one after
* we reclaim rcu_read_lock
*/
struct bio *bi;
atomic_inc(&rdev->nr_pending);
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
bi = bio_alloc(GFP_KERNEL, 0);
bi->bi_end_io = md_end_barrier;
bi->bi_private = rdev;
bi->bi_bdev = rdev->bdev;
atomic_inc(&mddev->flush_pending);
submit_bio(WRITE_BARRIER, bi);
rcu_read_lock();
rdev_dec_pending(rdev, mddev);
}
rcu_read_unlock();
}
static void md_submit_barrier(struct work_struct *ws)
{
mddev_t *mddev = container_of(ws, mddev_t, barrier_work);
struct bio *bio = mddev->barrier;
atomic_set(&mddev->flush_pending, 1);
if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
bio_endio(bio, -EOPNOTSUPP);
else if (bio->bi_size == 0)
/* an empty barrier - all done */
bio_endio(bio, 0);
else {
bio->bi_rw &= ~(1<<BIO_RW_BARRIER);
if (mddev->pers->make_request(mddev, bio))
generic_make_request(bio);
mddev->barrier = POST_REQUEST_BARRIER;
submit_barriers(mddev);
}
if (atomic_dec_and_test(&mddev->flush_pending)) {
mddev->barrier = NULL;
wake_up(&mddev->sb_wait);
}
}
void md_barrier_request(mddev_t *mddev, struct bio *bio)
{
spin_lock_irq(&mddev->write_lock);
wait_event_lock_irq(mddev->sb_wait,
!mddev->barrier,
mddev->write_lock, /*nothing*/);
mddev->barrier = bio;
spin_unlock_irq(&mddev->write_lock);
atomic_set(&mddev->flush_pending, 1);
INIT_WORK(&mddev->barrier_work, md_submit_barrier);
submit_barriers(mddev);
if (atomic_dec_and_test(&mddev->flush_pending))
schedule_work(&mddev->barrier_work);
}
EXPORT_SYMBOL(md_barrier_request);
static inline mddev_t *mddev_get(mddev_t *mddev)
{
atomic_inc(&mddev->active);
return mddev;
}
static void mddev_delayed_delete(struct work_struct *ws);
static void mddev_put(mddev_t *mddev)
{
if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
return;
if (!mddev->raid_disks && list_empty(&mddev->disks) &&
mddev->ctime == 0 && !mddev->hold_active) {
/* Array is not configured at all, and not held active,
* so destroy it */
list_del(&mddev->all_mddevs);
if (mddev->gendisk) {
/* we did a probe so need to clean up.
* Call schedule_work inside the spinlock
* so that flush_scheduled_work() after
* mddev_find will succeed in waiting for the
* work to be done.
*/
INIT_WORK(&mddev->del_work, mddev_delayed_delete);
schedule_work(&mddev->del_work);
} else
kfree(mddev);
}
spin_unlock(&all_mddevs_lock);
}
static void mddev_init(mddev_t *mddev)
{
mutex_init(&mddev->open_mutex);
mutex_init(&mddev->reconfig_mutex);
mutex_init(&mddev->bitmap_info.mutex);
INIT_LIST_HEAD(&mddev->disks);
INIT_LIST_HEAD(&mddev->all_mddevs);
init_timer(&mddev->safemode_timer);
atomic_set(&mddev->active, 1);
atomic_set(&mddev->openers, 0);
atomic_set(&mddev->active_io, 0);
spin_lock_init(&mddev->write_lock);
atomic_set(&mddev->flush_pending, 0);
init_waitqueue_head(&mddev->sb_wait);
init_waitqueue_head(&mddev->recovery_wait);
mddev->reshape_position = MaxSector;
mddev->resync_min = 0;
mddev->resync_max = MaxSector;
mddev->level = LEVEL_NONE;
}
static mddev_t * mddev_find(dev_t unit)
{
mddev_t *mddev, *new = NULL;
retry:
spin_lock(&all_mddevs_lock);
if (unit) {
list_for_each_entry(mddev, &all_mddevs, all_mddevs)
if (mddev->unit == unit) {
mddev_get(mddev);
spin_unlock(&all_mddevs_lock);
kfree(new);
return mddev;
}
if (new) {
list_add(&new->all_mddevs, &all_mddevs);
spin_unlock(&all_mddevs_lock);
new->hold_active = UNTIL_IOCTL;
return new;
}
} else if (new) {
/* find an unused unit number */
static int next_minor = 512;
int start = next_minor;
int is_free = 0;
int dev = 0;
while (!is_free) {
dev = MKDEV(MD_MAJOR, next_minor);
next_minor++;
if (next_minor > MINORMASK)
next_minor = 0;
if (next_minor == start) {
/* Oh dear, all in use. */
spin_unlock(&all_mddevs_lock);
kfree(new);
return NULL;
}
is_free = 1;
list_for_each_entry(mddev, &all_mddevs, all_mddevs)
if (mddev->unit == dev) {
is_free = 0;
break;
}
}
new->unit = dev;
new->md_minor = MINOR(dev);
new->hold_active = UNTIL_STOP;
list_add(&new->all_mddevs, &all_mddevs);
spin_unlock(&all_mddevs_lock);
return new;
}
spin_unlock(&all_mddevs_lock);
new = kzalloc(sizeof(*new), GFP_KERNEL);
if (!new)
return NULL;
new->unit = unit;
if (MAJOR(unit) == MD_MAJOR)
new->md_minor = MINOR(unit);
else
new->md_minor = MINOR(unit) >> MdpMinorShift;
mddev_init(new);
goto retry;
}
static inline int mddev_lock(mddev_t * mddev)
{
return mutex_lock_interruptible(&mddev->reconfig_mutex);
}
static inline int mddev_is_locked(mddev_t *mddev)
{
return mutex_is_locked(&mddev->reconfig_mutex);
}
static inline int mddev_trylock(mddev_t * mddev)
{
return mutex_trylock(&mddev->reconfig_mutex);
}
static struct attribute_group md_redundancy_group;
static void mddev_unlock(mddev_t * mddev)
{
if (mddev->to_remove) {
/* These cannot be removed under reconfig_mutex as
* an access to the files will try to take reconfig_mutex
* while holding the file unremovable, which leads to
* a deadlock.
* So hold open_mutex instead - we are allowed to take
* it while holding reconfig_mutex, and md_run can
* use it to wait for the remove to complete.
*/
struct attribute_group *to_remove = mddev->to_remove;
mddev->to_remove = NULL;
mutex_lock(&mddev->open_mutex);
mutex_unlock(&mddev->reconfig_mutex);
if (to_remove != &md_redundancy_group)
sysfs_remove_group(&mddev->kobj, to_remove);
if (mddev->pers == NULL ||
mddev->pers->sync_request == NULL) {
sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
if (mddev->sysfs_action)
sysfs_put(mddev->sysfs_action);
mddev->sysfs_action = NULL;
}
mutex_unlock(&mddev->open_mutex);
} else
mutex_unlock(&mddev->reconfig_mutex);
md_wakeup_thread(mddev->thread);
}
static mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
{
mdk_rdev_t *rdev;
list_for_each_entry(rdev, &mddev->disks, same_set)
if (rdev->desc_nr == nr)
return rdev;
return NULL;
}
static mdk_rdev_t * find_rdev(mddev_t * mddev, dev_t dev)
{
mdk_rdev_t *rdev;
list_for_each_entry(rdev, &mddev->disks, same_set)
if (rdev->bdev->bd_dev == dev)
return rdev;
return NULL;
}
static struct mdk_personality *find_pers(int level, char *clevel)
{
struct mdk_personality *pers;
list_for_each_entry(pers, &pers_list, list) {
if (level != LEVEL_NONE && pers->level == level)
return pers;
if (strcmp(pers->name, clevel)==0)
return pers;
}
return NULL;
}
/* return the offset of the super block in 512byte sectors */
static inline sector_t calc_dev_sboffset(struct block_device *bdev)
{
sector_t num_sectors = bdev->bd_inode->i_size / 512;
return MD_NEW_SIZE_SECTORS(num_sectors);
}
static int alloc_disk_sb(mdk_rdev_t * rdev)
{
if (rdev->sb_page)
MD_BUG();
rdev->sb_page = alloc_page(GFP_KERNEL);
if (!rdev->sb_page) {
printk(KERN_ALERT "md: out of memory.\n");
return -ENOMEM;
}
return 0;
}
static void free_disk_sb(mdk_rdev_t * rdev)
{
if (rdev->sb_page) {
put_page(rdev->sb_page);
rdev->sb_loaded = 0;
rdev->sb_page = NULL;
rdev->sb_start = 0;
rdev->sectors = 0;
}
}
static void super_written(struct bio *bio, int error)
{
mdk_rdev_t *rdev = bio->bi_private;
mddev_t *mddev = rdev->mddev;
if (error || !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
printk("md: super_written gets error=%d, uptodate=%d\n",
error, test_bit(BIO_UPTODATE, &bio->bi_flags));
WARN_ON(test_bit(BIO_UPTODATE, &bio->bi_flags));
md_error(mddev, rdev);
}
if (atomic_dec_and_test(&mddev->pending_writes))
wake_up(&mddev->sb_wait);
bio_put(bio);
}
static void super_written_barrier(struct bio *bio, int error)
{
struct bio *bio2 = bio->bi_private;
mdk_rdev_t *rdev = bio2->bi_private;
mddev_t *mddev = rdev->mddev;
if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
error == -EOPNOTSUPP) {
unsigned long flags;
/* barriers don't appear to be supported :-( */
set_bit(BarriersNotsupp, &rdev->flags);
mddev->barriers_work = 0;
spin_lock_irqsave(&mddev->write_lock, flags);
bio2->bi_next = mddev->biolist;
mddev->biolist = bio2;
spin_unlock_irqrestore(&mddev->write_lock, flags);
wake_up(&mddev->sb_wait);
bio_put(bio);
} else {
bio_put(bio2);
bio->bi_private = rdev;
super_written(bio, error);
}
}
void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
sector_t sector, int size, struct page *page)
{
/* write first size bytes of page to sector of rdev
* Increment mddev->pending_writes before returning
* and decrement it on completion, waking up sb_wait
* if zero is reached.
* If an error occurred, call md_error
*
* As we might need to resubmit the request if BIO_RW_BARRIER
* causes ENOTSUPP, we allocate a spare bio...
*/
struct bio *bio = bio_alloc(GFP_NOIO, 1);
int rw = (1<<BIO_RW) | (1<<BIO_RW_SYNCIO) | (1<<BIO_RW_UNPLUG);
bio->bi_bdev = rdev->bdev;
bio->bi_sector = sector;
bio_add_page(bio, page, size, 0);
bio->bi_private = rdev;
bio->bi_end_io = super_written;
bio->bi_rw = rw;
atomic_inc(&mddev->pending_writes);
if (!test_bit(BarriersNotsupp, &rdev->flags)) {
struct bio *rbio;
rw |= (1<<BIO_RW_BARRIER);
rbio = bio_clone(bio, GFP_NOIO);
rbio->bi_private = bio;
rbio->bi_end_io = super_written_barrier;
submit_bio(rw, rbio);
} else
submit_bio(rw, bio);
}
void md_super_wait(mddev_t *mddev)
{
/* wait for all superblock writes that were scheduled to complete.
* if any had to be retried (due to BARRIER problems), retry them
*/
DEFINE_WAIT(wq);
for(;;) {
prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
if (atomic_read(&mddev->pending_writes)==0)
break;
while (mddev->biolist) {
struct bio *bio;
spin_lock_irq(&mddev->write_lock);
bio = mddev->biolist;
mddev->biolist = bio->bi_next ;
bio->bi_next = NULL;
spin_unlock_irq(&mddev->write_lock);
submit_bio(bio->bi_rw, bio);
}
schedule();
}
finish_wait(&mddev->sb_wait, &wq);
}
static void bi_complete(struct bio *bio, int error)
{
complete((struct completion*)bio->bi_private);
}
int sync_page_io(struct block_device *bdev, sector_t sector, int size,
struct page *page, int rw)
{
struct bio *bio = bio_alloc(GFP_NOIO, 1);
struct completion event;
int ret;
rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
bio->bi_bdev = bdev;
bio->bi_sector = sector;
bio_add_page(bio, page, size, 0);
init_completion(&event);
bio->bi_private = &event;
bio->bi_end_io = bi_complete;
submit_bio(rw, bio);
wait_for_completion(&event);
ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
bio_put(bio);
return ret;
}
EXPORT_SYMBOL_GPL(sync_page_io);
static int read_disk_sb(mdk_rdev_t * rdev, int size)
{
char b[BDEVNAME_SIZE];
if (!rdev->sb_page) {
MD_BUG();
return -EINVAL;
}
if (rdev->sb_loaded)
return 0;
if (!sync_page_io(rdev->bdev, rdev->sb_start, size, rdev->sb_page, READ))
goto fail;
rdev->sb_loaded = 1;
return 0;
fail:
printk(KERN_WARNING "md: disabled device %s, could not read superblock.\n",
bdevname(rdev->bdev,b));
return -EINVAL;
}
static int uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
return sb1->set_uuid0 == sb2->set_uuid0 &&
sb1->set_uuid1 == sb2->set_uuid1 &&
sb1->set_uuid2 == sb2->set_uuid2 &&
sb1->set_uuid3 == sb2->set_uuid3;
}
static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
{
int ret;
mdp_super_t *tmp1, *tmp2;
tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);
if (!tmp1 || !tmp2) {
ret = 0;
printk(KERN_INFO "md.c sb_equal(): failed to allocate memory!\n");
goto abort;
}
*tmp1 = *sb1;
*tmp2 = *sb2;
/*
* nr_disks is not constant
*/
tmp1->nr_disks = 0;
tmp2->nr_disks = 0;
ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
abort:
kfree(tmp1);
kfree(tmp2);
return ret;
}
static u32 md_csum_fold(u32 csum)
{
csum = (csum & 0xffff) + (csum >> 16);
return (csum & 0xffff) + (csum >> 16);
}
static unsigned int calc_sb_csum(mdp_super_t * sb)
{
u64 newcsum = 0;
u32 *sb32 = (u32*)sb;
int i;
unsigned int disk_csum, csum;
disk_csum = sb->sb_csum;
sb->sb_csum = 0;
for (i = 0; i < MD_SB_BYTES/4 ; i++)
newcsum += sb32[i];
csum = (newcsum & 0xffffffff) + (newcsum>>32);
#ifdef CONFIG_ALPHA
/* This used to use csum_partial, which was wrong for several
* reasons including that different results are returned on
* different architectures. It isn't critical that we get exactly
* the same return value as before (we always csum_fold before
* testing, and that removes any differences). However as we
* know that csum_partial always returned a 16bit value on
* alphas, do a fold to maximise conformity to previous behaviour.
*/
sb->sb_csum = md_csum_fold(disk_csum);
#else
sb->sb_csum = disk_csum;
#endif
return csum;
}
/*
* Handle superblock details.
* We want to be able to handle multiple superblock formats
* so we have a common interface to them all, and an array of
* different handlers.
* We rely on user-space to write the initial superblock, and support
* reading and updating of superblocks.
* Interface methods are:
* int load_super(mdk_rdev_t *dev, mdk_rdev_t *refdev, int minor_version)
* loads and validates a superblock on dev.
* if refdev != NULL, compare superblocks on both devices
* Return:
* 0 - dev has a superblock that is compatible with refdev
* 1 - dev has a superblock that is compatible and newer than refdev
* so dev should be used as the refdev in future
* -EINVAL superblock incompatible or invalid
* -othererror e.g. -EIO
*
* int validate_super(mddev_t *mddev, mdk_rdev_t *dev)
* Verify that dev is acceptable into mddev.
* The first time, mddev->raid_disks will be 0, and data from
* dev should be merged in. Subsequent calls check that dev
* is new enough. Return 0 or -EINVAL
*
* void sync_super(mddev_t *mddev, mdk_rdev_t *dev)
* Update the superblock for rdev with data in mddev
* This does not write to disc.
*
*/
struct super_type {
char *name;
struct module *owner;
int (*load_super)(mdk_rdev_t *rdev, mdk_rdev_t *refdev,
int minor_version);
int (*validate_super)(mddev_t *mddev, mdk_rdev_t *rdev);
void (*sync_super)(mddev_t *mddev, mdk_rdev_t *rdev);
unsigned long long (*rdev_size_change)(mdk_rdev_t *rdev,
sector_t num_sectors);
};
/*
* Check that the given mddev has no bitmap.
*
* This function is called from the run method of all personalities that do not
* support bitmaps. It prints an error message and returns non-zero if mddev
* has a bitmap. Otherwise, it returns 0.
*
*/
int md_check_no_bitmap(mddev_t *mddev)
{
if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
return 0;
printk(KERN_ERR "%s: bitmaps are not supported for %s\n",
mdname(mddev), mddev->pers->name);
return 1;
}
EXPORT_SYMBOL(md_check_no_bitmap);
/*
* load_super for 0.90.0
*/
static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
{
char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
mdp_super_t *sb;
int ret;
/*
* Calculate the position of the superblock (512byte sectors),
* it's at the end of the disk.
*
* It also happens to be a multiple of 4Kb.
*/
rdev->sb_start = calc_dev_sboffset(rdev->bdev);
ret = read_disk_sb(rdev, MD_SB_BYTES);
if (ret) return ret;
ret = -EINVAL;
bdevname(rdev->bdev, b);
sb = (mdp_super_t*)page_address(rdev->sb_page);
if (sb->md_magic != MD_SB_MAGIC) {
printk(KERN_ERR "md: invalid raid superblock magic on %s\n",
b);
goto abort;
}
if (sb->major_version != 0 ||
sb->minor_version < 90 ||
sb->minor_version > 91) {
printk(KERN_WARNING "Bad version number %d.%d on %s\n",
sb->major_version, sb->minor_version,
b);
goto abort;
}
if (sb->raid_disks <= 0)
goto abort;
if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
b);
goto abort;
}
rdev->preferred_minor = sb->md_minor;
rdev->data_offset = 0;
rdev->sb_size = MD_SB_BYTES;
if (sb->level == LEVEL_MULTIPATH)
rdev->desc_nr = -1;
else
rdev->desc_nr = sb->this_disk.number;
if (!refdev) {
ret = 1;
} else {
__u64 ev1, ev2;
mdp_super_t *refsb = (mdp_super_t*)page_address(refdev->sb_page);
if (!uuid_equal(refsb, sb)) {
printk(KERN_WARNING "md: %s has different UUID to %s\n",
b, bdevname(refdev->bdev,b2));
goto abort;
}
if (!sb_equal(refsb, sb)) {
printk(KERN_WARNING "md: %s has same UUID"
" but different superblock to %s\n",
b, bdevname(refdev->bdev, b2));
goto abort;
}
ev1 = md_event(sb);
ev2 = md_event(refsb);
if (ev1 > ev2)
ret = 1;
else
ret = 0;
}
rdev->sectors = rdev->sb_start;
if (rdev->sectors < sb->size * 2 && sb->level > 1)
/* "this cannot possibly happen" ... */
ret = -EINVAL;