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linux/drivers/md/raid10.c
K.Tanaka a07e6ab41b md: the md RAID10 resync thread could cause a md RAID10 array deadlock 
This message describes another issue about md RAID10 found by testing the
2.6.24 md RAID10 using new scsi fault injection framework.

Abstract:

When a scsi error results in disabling a disk during RAID10 recovery, the
resync threads of md RAID10 could stall.

This case, the raid array has already been broken and it may not matter.  But
I think stall is not preferable.  If it occurs, even shutdown or reboot will
fail because of resource busy.

The deadlock mechanism:

The r10bio_s structure has a "remaining" member to keep track of BIOs yet to
be handled when recovering.  The "remaining" counter is incremented when
building a BIO in sync_request() and is decremented when finish a BIO in
end_sync_write().

If building a BIO fails for some reasons in sync_request(), the "remaining"
should be decremented if it has already been incremented.  I found a case
where this decrement is forgotten.  This causes a md_do_sync() deadlock
because md_do_sync() waits for md_done_sync() called by end_sync_write(), but
end_sync_write() never calls md_done_sync() because of the "remaining" counter
mismatch.

For example, this problem would be reproduced in the following case:

Personalities : [raid10]
md0 : active raid10 sdf1[4] sde1[5](F) sdd1[2] sdc1[1] sdb1[6](F)
      3919616 blocks 64K chunks 2 near-copies [4/2] [_UU_]
      [>....................]  recovery =  2.2% (45376/1959808) finish=0.7min speed=45376K/sec

This case, sdf1 is recovering, sdb1 and sde1 are disabled.
An additional error with detaching sdd will cause a deadlock.

md0 : active raid10 sdf1[4] sde1[5](F) sdd1[6](F) sdc1[1] sdb1[7](F)
      3919616 blocks 64K chunks 2 near-copies [4/1] [_U__]
      [=>...................]  recovery =  5.0% (99520/1959808) finish=5.9min speed=5237K/sec

 2739 ?        S<     0:17 [md0_raid10]
28608 ?        D<     0:00 [md0_resync]
28629 pts/1    Ss     0:00 bash
28830 pts/1    R+     0:00 ps ax
31819 ?        D<     0:00 [kjournald]

The resync thread keeps working, but actually it is deadlocked.

Patch:
By this patch, the remaining counter will be decremented if needed.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-04 16:35:18 -08:00

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/*
* raid10.c : Multiple Devices driver for Linux
*
* Copyright (C) 2000-2004 Neil Brown
*
* RAID-10 support for md.
*
* Base on code in raid1.c. See raid1.c for futher copyright information.
*
*
* 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 "dm-bio-list.h"
#include <linux/raid/raid10.h>
#include <linux/raid/bitmap.h>
/*
* RAID10 provides a combination of RAID0 and RAID1 functionality.
* The layout of data is defined by
* chunk_size
* raid_disks
* near_copies (stored in low byte of layout)
* far_copies (stored in second byte of layout)
* far_offset (stored in bit 16 of layout )
*
* The data to be stored is divided into chunks using chunksize.
* Each device is divided into far_copies sections.
* In each section, chunks are laid out in a style similar to raid0, but
* near_copies copies of each chunk is stored (each on a different drive).
* The starting device for each section is offset near_copies from the starting
* device of the previous section.
* Thus they are (near_copies*far_copies) of each chunk, and each is on a different
* drive.
* near_copies and far_copies must be at least one, and their product is at most
* raid_disks.
*
* If far_offset is true, then the far_copies are handled a bit differently.
* The copies are still in different stripes, but instead of be very far apart
* on disk, there are adjacent stripes.
*/
/*
* Number of guaranteed r10bios in case of extreme VM load:
*/
#define NR_RAID10_BIOS 256
static void unplug_slaves(mddev_t *mddev);
static void allow_barrier(conf_t *conf);
static void lower_barrier(conf_t *conf);
static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
{
conf_t *conf = data;
r10bio_t *r10_bio;
int size = offsetof(struct r10bio_s, devs[conf->copies]);
/* allocate a r10bio with room for raid_disks entries in the bios array */
r10_bio = kzalloc(size, gfp_flags);
if (!r10_bio)
unplug_slaves(conf->mddev);
return r10_bio;
}
static void r10bio_pool_free(void *r10_bio, void *data)
{
kfree(r10_bio);
}
#define RESYNC_BLOCK_SIZE (64*1024)
//#define RESYNC_BLOCK_SIZE PAGE_SIZE
#define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
#define RESYNC_WINDOW (2048*1024)
/*
* When performing a resync, we need to read and compare, so
* we need as many pages are there are copies.
* When performing a recovery, we need 2 bios, one for read,
* one for write (we recover only one drive per r10buf)
*
*/
static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
{
conf_t *conf = data;
struct page *page;
r10bio_t *r10_bio;
struct bio *bio;
int i, j;
int nalloc;
r10_bio = r10bio_pool_alloc(gfp_flags, conf);
if (!r10_bio) {
unplug_slaves(conf->mddev);
return NULL;
}
if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
nalloc = conf->copies; /* resync */
else
nalloc = 2; /* recovery */
/*
* Allocate bios.
*/
for (j = nalloc ; j-- ; ) {
bio = bio_alloc(gfp_flags, RESYNC_PAGES);
if (!bio)
goto out_free_bio;
r10_bio->devs[j].bio = bio;
}
/*
* Allocate RESYNC_PAGES data pages and attach them
* where needed.
*/
for (j = 0 ; j < nalloc; j++) {
bio = r10_bio->devs[j].bio;
for (i = 0; i < RESYNC_PAGES; i++) {
page = alloc_page(gfp_flags);
if (unlikely(!page))
goto out_free_pages;
bio->bi_io_vec[i].bv_page = page;
}
}
return r10_bio;
out_free_pages:
for ( ; i > 0 ; i--)
safe_put_page(bio->bi_io_vec[i-1].bv_page);
while (j--)
for (i = 0; i < RESYNC_PAGES ; i++)
safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
j = -1;
out_free_bio:
while ( ++j < nalloc )
bio_put(r10_bio->devs[j].bio);
r10bio_pool_free(r10_bio, conf);
return NULL;
}
static void r10buf_pool_free(void *__r10_bio, void *data)
{
int i;
conf_t *conf = data;
r10bio_t *r10bio = __r10_bio;
int j;
for (j=0; j < conf->copies; j++) {
struct bio *bio = r10bio->devs[j].bio;
if (bio) {
for (i = 0; i < RESYNC_PAGES; i++) {
safe_put_page(bio->bi_io_vec[i].bv_page);
bio->bi_io_vec[i].bv_page = NULL;
}
bio_put(bio);
}
}
r10bio_pool_free(r10bio, conf);
}
static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
{
int i;
for (i = 0; i < conf->copies; i++) {
struct bio **bio = & r10_bio->devs[i].bio;
if (*bio && *bio != IO_BLOCKED)
bio_put(*bio);
*bio = NULL;
}
}
static void free_r10bio(r10bio_t *r10_bio)
{
conf_t *conf = mddev_to_conf(r10_bio->mddev);
/*
* Wake up any possible resync thread that waits for the device
* to go idle.
*/
allow_barrier(conf);
put_all_bios(conf, r10_bio);
mempool_free(r10_bio, conf->r10bio_pool);
}
static void put_buf(r10bio_t *r10_bio)
{
conf_t *conf = mddev_to_conf(r10_bio->mddev);
mempool_free(r10_bio, conf->r10buf_pool);
lower_barrier(conf);
}
static void reschedule_retry(r10bio_t *r10_bio)
{
unsigned long flags;
mddev_t *mddev = r10_bio->mddev;
conf_t *conf = mddev_to_conf(mddev);
spin_lock_irqsave(&conf->device_lock, flags);
list_add(&r10_bio->retry_list, &conf->retry_list);
conf->nr_queued ++;
spin_unlock_irqrestore(&conf->device_lock, flags);
md_wakeup_thread(mddev->thread);
}
/*
* raid_end_bio_io() is called when we have finished servicing a mirrored
* operation and are ready to return a success/failure code to the buffer
* cache layer.
*/
static void raid_end_bio_io(r10bio_t *r10_bio)
{
struct bio *bio = r10_bio->master_bio;
bio_endio(bio,
test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
free_r10bio(r10_bio);
}
/*
* Update disk head position estimator based on IRQ completion info.
*/
static inline void update_head_pos(int slot, r10bio_t *r10_bio)
{
conf_t *conf = mddev_to_conf(r10_bio->mddev);
conf->mirrors[r10_bio->devs[slot].devnum].head_position =
r10_bio->devs[slot].addr + (r10_bio->sectors);
}
static void raid10_end_read_request(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
int slot, dev;
conf_t *conf = mddev_to_conf(r10_bio->mddev);
slot = r10_bio->read_slot;
dev = r10_bio->devs[slot].devnum;
/*
* this branch is our 'one mirror IO has finished' event handler:
*/
update_head_pos(slot, r10_bio);
if (uptodate) {
/*
* Set R10BIO_Uptodate in our master bio, so that
* we will return a good error code to the higher
* levels even if IO on some other mirrored buffer fails.
*
* The 'master' represents the composite IO operation to
* user-side. So if something waits for IO, then it will
* wait for the 'master' bio.
*/
set_bit(R10BIO_Uptodate, &r10_bio->state);
raid_end_bio_io(r10_bio);
} else {
/*
* oops, read error:
*/
char b[BDEVNAME_SIZE];
if (printk_ratelimit())
printk(KERN_ERR "raid10: %s: rescheduling sector %llu\n",
bdevname(conf->mirrors[dev].rdev->bdev,b), (unsigned long long)r10_bio->sector);
reschedule_retry(r10_bio);
}
rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
}
static void raid10_end_write_request(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
int slot, dev;
conf_t *conf = mddev_to_conf(r10_bio->mddev);
for (slot = 0; slot < conf->copies; slot++)
if (r10_bio->devs[slot].bio == bio)
break;
dev = r10_bio->devs[slot].devnum;
/*
* this branch is our 'one mirror IO has finished' event handler:
*/
if (!uptodate) {
md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
/* an I/O failed, we can't clear the bitmap */
set_bit(R10BIO_Degraded, &r10_bio->state);
} else
/*
* Set R10BIO_Uptodate in our master bio, so that
* we will return a good error code for to the higher
* levels even if IO on some other mirrored buffer fails.
*
* The 'master' represents the composite IO operation to
* user-side. So if something waits for IO, then it will
* wait for the 'master' bio.
*/
set_bit(R10BIO_Uptodate, &r10_bio->state);
update_head_pos(slot, r10_bio);
/*
*
* Let's see if all mirrored write operations have finished
* already.
*/
if (atomic_dec_and_test(&r10_bio->remaining)) {
/* clear the bitmap if all writes complete successfully */
bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
r10_bio->sectors,
!test_bit(R10BIO_Degraded, &r10_bio->state),
0);
md_write_end(r10_bio->mddev);
raid_end_bio_io(r10_bio);
}
rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
}
/*
* RAID10 layout manager
* Aswell as the chunksize and raid_disks count, there are two
* parameters: near_copies and far_copies.
* near_copies * far_copies must be <= raid_disks.
* Normally one of these will be 1.
* If both are 1, we get raid0.
* If near_copies == raid_disks, we get raid1.
*
* Chunks are layed out in raid0 style with near_copies copies of the
* first chunk, followed by near_copies copies of the next chunk and
* so on.
* If far_copies > 1, then after 1/far_copies of the array has been assigned
* as described above, we start again with a device offset of near_copies.
* So we effectively have another copy of the whole array further down all
* the drives, but with blocks on different drives.
* With this layout, and block is never stored twice on the one device.
*
* raid10_find_phys finds the sector offset of a given virtual sector
* on each device that it is on.
*
* raid10_find_virt does the reverse mapping, from a device and a
* sector offset to a virtual address
*/
static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
{
int n,f;
sector_t sector;
sector_t chunk;
sector_t stripe;
int dev;
int slot = 0;
/* now calculate first sector/dev */
chunk = r10bio->sector >> conf->chunk_shift;
sector = r10bio->sector & conf->chunk_mask;
chunk *= conf->near_copies;
stripe = chunk;
dev = sector_div(stripe, conf->raid_disks);
if (conf->far_offset)
stripe *= conf->far_copies;
sector += stripe << conf->chunk_shift;
/* and calculate all the others */
for (n=0; n < conf->near_copies; n++) {
int d = dev;
sector_t s = sector;
r10bio->devs[slot].addr = sector;
r10bio->devs[slot].devnum = d;
slot++;
for (f = 1; f < conf->far_copies; f++) {
d += conf->near_copies;
if (d >= conf->raid_disks)
d -= conf->raid_disks;
s += conf->stride;
r10bio->devs[slot].devnum = d;
r10bio->devs[slot].addr = s;
slot++;
}
dev++;
if (dev >= conf->raid_disks) {
dev = 0;
sector += (conf->chunk_mask + 1);
}
}
BUG_ON(slot != conf->copies);
}
static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
{
sector_t offset, chunk, vchunk;
offset = sector & conf->chunk_mask;
if (conf->far_offset) {
int fc;
chunk = sector >> conf->chunk_shift;
fc = sector_div(chunk, conf->far_copies);
dev -= fc * conf->near_copies;
if (dev < 0)
dev += conf->raid_disks;
} else {
while (sector >= conf->stride) {
sector -= conf->stride;
if (dev < conf->near_copies)
dev += conf->raid_disks - conf->near_copies;
else
dev -= conf->near_copies;
}
chunk = sector >> conf->chunk_shift;
}
vchunk = chunk * conf->raid_disks + dev;
sector_div(vchunk, conf->near_copies);
return (vchunk << conf->chunk_shift) + offset;
}
/**
* raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
* @q: request queue
* @bio: the buffer head that's been built up so far
* @biovec: the request that could be merged to it.
*
* Return amount of bytes we can accept at this offset
* If near_copies == raid_disk, there are no striping issues,
* but in that case, the function isn't called at all.
*/
static int raid10_mergeable_bvec(struct request_queue *q, struct bio *bio,
struct bio_vec *bio_vec)
{
mddev_t *mddev = q->queuedata;
sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
int max;
unsigned int chunk_sectors = mddev->chunk_size >> 9;
unsigned int bio_sectors = bio->bi_size >> 9;
max = (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
if (max < 0) max = 0; /* bio_add cannot handle a negative return */
if (max <= bio_vec->bv_len && bio_sectors == 0)
return bio_vec->bv_len;
else
return max;
}
/*
* This routine returns the disk from which the requested read should
* be done. There is a per-array 'next expected sequential IO' sector
* number - if this matches on the next IO then we use the last disk.
* There is also a per-disk 'last know head position' sector that is
* maintained from IRQ contexts, both the normal and the resync IO
* completion handlers update this position correctly. If there is no
* perfect sequential match then we pick the disk whose head is closest.
*
* If there are 2 mirrors in the same 2 devices, performance degrades
* because position is mirror, not device based.
*
* The rdev for the device selected will have nr_pending incremented.
*/
/*
* FIXME: possibly should rethink readbalancing and do it differently
* depending on near_copies / far_copies geometry.
*/
static int read_balance(conf_t *conf, r10bio_t *r10_bio)
{
const unsigned long this_sector = r10_bio->sector;
int disk, slot, nslot;
const int sectors = r10_bio->sectors;
sector_t new_distance, current_distance;
mdk_rdev_t *rdev;
raid10_find_phys(conf, r10_bio);
rcu_read_lock();
/*
* Check if we can balance. We can balance on the whole
* device if no resync is going on (recovery is ok), or below
* the resync window. We take the first readable disk when
* above the resync window.
*/
if (conf->mddev->recovery_cp < MaxSector
&& (this_sector + sectors >= conf->next_resync)) {
/* make sure that disk is operational */
slot = 0;
disk = r10_bio->devs[slot].devnum;
while ((rdev = rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
r10_bio->devs[slot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags)) {
slot++;
if (slot == conf->copies) {
slot = 0;
disk = -1;
break;
}
disk = r10_bio->devs[slot].devnum;
}
goto rb_out;
}
/* make sure the disk is operational */
slot = 0;
disk = r10_bio->devs[slot].devnum;
while ((rdev=rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
r10_bio->devs[slot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags)) {
slot ++;
if (slot == conf->copies) {
disk = -1;
goto rb_out;
}
disk = r10_bio->devs[slot].devnum;
}
current_distance = abs(r10_bio->devs[slot].addr -
conf->mirrors[disk].head_position);
/* Find the disk whose head is closest,
* or - for far > 1 - find the closest to partition beginning */
for (nslot = slot; nslot < conf->copies; nslot++) {
int ndisk = r10_bio->devs[nslot].devnum;
if ((rdev=rcu_dereference(conf->mirrors[ndisk].rdev)) == NULL ||
r10_bio->devs[nslot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags))
continue;
/* This optimisation is debatable, and completely destroys
* sequential read speed for 'far copies' arrays. So only
* keep it for 'near' arrays, and review those later.
*/
if (conf->near_copies > 1 && !atomic_read(&rdev->nr_pending)) {
disk = ndisk;
slot = nslot;
break;
}
/* for far > 1 always use the lowest address */
if (conf->far_copies > 1)
new_distance = r10_bio->devs[nslot].addr;
else
new_distance = abs(r10_bio->devs[nslot].addr -
conf->mirrors[ndisk].head_position);
if (new_distance < current_distance) {
current_distance = new_distance;
disk = ndisk;
slot = nslot;
}
}
rb_out:
r10_bio->read_slot = slot;
/* conf->next_seq_sect = this_sector + sectors;*/
if (disk >= 0 && (rdev=rcu_dereference(conf->mirrors[disk].rdev))!= NULL)
atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
else
disk = -1;
rcu_read_unlock();
return disk;
}
static void unplug_slaves(mddev_t *mddev)
{
conf_t *conf = mddev_to_conf(mddev);
int i;
rcu_read_lock();
for (i=0; i<mddev->raid_disks; i++) {
mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
blk_unplug(r_queue);
rdev_dec_pending(rdev, mddev);
rcu_read_lock();
}
}
rcu_read_unlock();
}
static void raid10_unplug(struct request_queue *q)
{
mddev_t *mddev = q->queuedata;
unplug_slaves(q->queuedata);
md_wakeup_thread(mddev->thread);
}
static int raid10_congested(void *data, int bits)
{
mddev_t *mddev = data;
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 = rcu_dereference(conf->mirrors[i].rdev);
if (rdev && !test_bit(Faulty, &rdev->flags)) {
struct request_queue *q = bdev_get_queue(rdev->bdev);
ret |= bdi_congested(&q->backing_dev_info, bits);
}
}
rcu_read_unlock();
return ret;
}
static int flush_pending_writes(conf_t *conf)
{
/* Any writes that have been queued but are awaiting
* bitmap updates get flushed here.
* We return 1 if any requests were actually submitted.
*/
int rv = 0;
spin_lock_irq(&conf->device_lock);
if (conf->pending_bio_list.head) {
struct bio *bio;
bio = bio_list_get(&conf->pending_bio_list);
blk_remove_plug(conf->mddev->queue);
spin_unlock_irq(&conf->device_lock);
/* flush any pending bitmap writes to disk
* before proceeding w/ I/O */
bitmap_unplug(conf->mddev->bitmap);
while (bio) { /* submit pending writes */
struct bio *next = bio->bi_next;
bio->bi_next = NULL;
generic_make_request(bio);
bio = next;
}
rv = 1;
} else
spin_unlock_irq(&conf->device_lock);
return rv;
}
/* Barriers....
* Sometimes we need to suspend IO while we do something else,
* either some resync/recovery, or reconfigure the array.
* To do this we raise a 'barrier'.
* The 'barrier' is a counter that can be raised multiple times
* to count how many activities are happening which preclude
* normal IO.
* We can only raise the barrier if there is no pending IO.
* i.e. if nr_pending == 0.
* We choose only to raise the barrier if no-one is waiting for the
* barrier to go down. This means that as soon as an IO request
* is ready, no other operations which require a barrier will start
* until the IO request has had a chance.
*
* So: regular IO calls 'wait_barrier'. When that returns there
* is no backgroup IO happening, It must arrange to call
* allow_barrier when it has finished its IO.
* backgroup IO calls must call raise_barrier. Once that returns
* there is no normal IO happeing. It must arrange to call
* lower_barrier when the particular background IO completes.
*/
#define RESYNC_DEPTH 32
static void raise_barrier(conf_t *conf, int force)
{
BUG_ON(force && !conf->barrier);
spin_lock_irq(&conf->resync_lock);
/* Wait until no block IO is waiting (unless 'force') */
wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
conf->resync_lock,
raid10_unplug(conf->mddev->queue));
/* block any new IO from starting */
conf->barrier++;
/* No wait for all pending IO to complete */
wait_event_lock_irq(conf->wait_barrier,
!conf->nr_pending && conf->barrier < RESYNC_DEPTH,
conf->resync_lock,
raid10_unplug(conf->mddev->queue));
spin_unlock_irq(&conf->resync_lock);
}
static void lower_barrier(conf_t *conf)
{
unsigned long flags;
spin_lock_irqsave(&conf->resync_lock, flags);
conf->barrier--;
spin_unlock_irqrestore(&conf->resync_lock, flags);
wake_up(&conf->wait_barrier);
}
static void wait_barrier(conf_t *conf)
{
spin_lock_irq(&conf->resync_lock);
if (conf->barrier) {
conf->nr_waiting++;
wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
conf->resync_lock,
raid10_unplug(conf->mddev->queue));
conf->nr_waiting--;
}
conf->nr_pending++;
spin_unlock_irq(&conf->resync_lock);
}
static void allow_barrier(conf_t *conf)
{
unsigned long flags;
spin_lock_irqsave(&conf->resync_lock, flags);
conf->nr_pending--;
spin_unlock_irqrestore(&conf->resync_lock, flags);
wake_up(&conf->wait_barrier);
}
static void freeze_array(conf_t *conf)
{
/* stop syncio and normal IO and wait for everything to
* go quiet.
* We increment barrier and nr_waiting, and then
* wait until nr_pending match nr_queued+1
* This is called in the context of one normal IO request
* that has failed. Thus any sync request that might be pending
* will be blocked by nr_pending, and we need to wait for
* pending IO requests to complete or be queued for re-try.
* Thus the number queued (nr_queued) plus this request (1)
* must match the number of pending IOs (nr_pending) before
* we continue.
*/
spin_lock_irq(&conf->resync_lock);
conf->barrier++;
conf->nr_waiting++;
wait_event_lock_irq(conf->wait_barrier,
conf->nr_pending == conf->nr_queued+1,
conf->resync_lock,
({ flush_pending_writes(conf);
raid10_unplug(conf->mddev->queue); }));
spin_unlock_irq(&conf->resync_lock);
}
static void unfreeze_array(conf_t *conf)
{
/* reverse the effect of the freeze */
spin_lock_irq(&conf->resync_lock);
conf->barrier--;
conf->nr_waiting--;
wake_up(&conf->wait_barrier);
spin_unlock_irq(&conf->resync_lock);
}
static int make_request(struct request_queue *q, struct bio * bio)
{
mddev_t *mddev = q->queuedata;
conf_t *conf = mddev_to_conf(mddev);
mirror_info_t *mirror;
r10bio_t *r10_bio;
struct bio *read_bio;
int i;
int chunk_sects = conf->chunk_mask + 1;
const int rw = bio_data_dir(bio);
const int do_sync = bio_sync(bio);
struct bio_list bl;
unsigned long flags;
if (unlikely(bio_barrier(bio))) {
bio_endio(bio, -EOPNOTSUPP);
return 0;
}
/* If this request crosses a chunk boundary, we need to
* split it. This will only happen for 1 PAGE (or less) requests.
*/
if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
> chunk_sects &&
conf->near_copies < conf->raid_disks)) {
struct bio_pair *bp;
/* Sanity check -- queue functions should prevent this happening */
if (bio->bi_vcnt != 1 ||
bio->bi_idx != 0)
goto bad_map;
/* This is a one page bio that upper layers
* refuse to split for us, so we need to split it.
*/
bp = bio_split(bio, bio_split_pool,
chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
if (make_request(q, &bp->bio1))
generic_make_request(&bp->bio1);
if (make_request(q, &bp->bio2))
generic_make_request(&bp->bio2);
bio_pair_release(bp);
return 0;
bad_map:
printk("raid10_make_request bug: can't convert block across chunks"
" or bigger than %dk %llu %d\n", chunk_sects/2,
(unsigned long long)bio->bi_sector, bio->bi_size >> 10);
bio_io_error(bio);
return 0;
}
md_write_start(mddev, bio);
/*
* Register the new request and wait if the reconstruction
* thread has put up a bar for new requests.
* Continue immediately if no resync is active currently.
*/
wait_barrier(conf);
disk_stat_inc(mddev->gendisk, ios[rw]);
disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
r10_bio->master_bio = bio;
r10_bio->sectors = bio->bi_size >> 9;
r10_bio->mddev = mddev;
r10_bio->sector = bio->bi_sector;
r10_bio->state = 0;
if (rw == READ) {
/*
* read balancing logic:
*/
int disk = read_balance(conf, r10_bio);
int slot = r10_bio->read_slot;
if (disk < 0) {
raid_end_bio_io(r10_bio);
return 0;
}
mirror = conf->mirrors + disk;
read_bio = bio_clone(bio, GFP_NOIO);
r10_bio->devs[slot].bio = read_bio;
read_bio->bi_sector = r10_bio->devs[slot].addr +
mirror->rdev->data_offset;
read_bio->bi_bdev = mirror->rdev->bdev;
read_bio->bi_end_io = raid10_end_read_request;
read_bio->bi_rw = READ | do_sync;
read_bio->bi_private = r10_bio;
generic_make_request(read_bio);
return 0;
}
/*
* WRITE:
*/
/* first select target devices under spinlock and
* inc refcount on their rdev. Record them by setting
* bios[x] to bio
*/
raid10_find_phys(conf, r10_bio);
rcu_read_lock();
for (i = 0; i < conf->copies; i++) {
int d = r10_bio->devs[i].devnum;
mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
!test_bit(Faulty, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
r10_bio->devs[i].bio = bio;
} else {
r10_bio->devs[i].bio = NULL;
set_bit(R10BIO_Degraded, &r10_bio->state);
}
}
rcu_read_unlock();
atomic_set(&r10_bio->remaining, 0);
bio_list_init(&bl);
for (i = 0; i < conf->copies; i++) {
struct bio *mbio;
int d = r10_bio->devs[i].devnum;
if (!r10_bio->devs[i].bio)
continue;
mbio = bio_clone(bio, GFP_NOIO);
r10_bio->devs[i].bio = mbio;
mbio->bi_sector = r10_bio->devs[i].addr+
conf->mirrors[d].rdev->data_offset;
mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
mbio->bi_end_io = raid10_end_write_request;
mbio->bi_rw = WRITE | do_sync;
mbio->bi_private = r10_bio;
atomic_inc(&r10_bio->remaining);
bio_list_add(&bl, mbio);
}
if (unlikely(!atomic_read(&r10_bio->remaining))) {
/* the array is dead */
md_write_end(mddev);
raid_end_bio_io(r10_bio);
return 0;
}
bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
spin_lock_irqsave(&conf->device_lock, flags);
bio_list_merge(&conf->pending_bio_list, &bl);
blk_plug_device(mddev->queue);
spin_unlock_irqrestore(&conf->device_lock, flags);
/* In case raid10d snuck in to freeze_array */
wake_up(&conf->wait_barrier);
if (do_sync)
md_wakeup_thread(mddev->thread);
return 0;
}
static void status(struct seq_file *seq, mddev_t *mddev)
{
conf_t *conf = mddev_to_conf(mddev);
int i;
if (conf->near_copies < conf->raid_disks)
seq_printf(seq, " %dK chunks", mddev->chunk_size/1024);
if (conf->near_copies > 1)
seq_printf(seq, " %d near-copies", conf->near_copies);
if (conf->far_copies > 1) {
if (conf->far_offset)
seq_printf(seq, " %d offset-copies", conf->far_copies);
else
seq_printf(seq, " %d far-copies", conf->far_copies);
}
seq_printf(seq, " [%d/%d] [", conf->raid_disks,
conf->raid_disks - mddev->degraded);
for (i = 0; i < conf->raid_disks; i++)
seq_printf(seq, "%s",
conf->mirrors[i].rdev &&
test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
seq_printf(seq, "]");
}
static void error(mddev_t *mddev, mdk_rdev_t *rdev)
{
char b[BDEVNAME_SIZE];
conf_t *conf = mddev_to_conf(mddev);
/*
* If it is not operational, then we have already marked it as dead
* else if it is the last working disks, ignore the error, let the
* next level up know.
* else mark the drive as failed
*/
if (test_bit(In_sync, &rdev->flags)
&& conf->raid_disks-mddev->degraded == 1)
/*
* Don't fail the drive, just return an IO error.
* The test should really be more sophisticated than
* "working_disks == 1", but it isn't critical, and
* can wait until we do more sophisticated "is the drive
* really dead" tests...
*/
return;
if (test_and_clear_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
set_bit(MD_RECOVERY_ERR, &mddev->recovery);
}
set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
" Operation continuing on %d devices\n",
bdevname(rdev->bdev,b), conf->raid_disks - mddev->degraded);
}
static void print_conf(conf_t *conf)
{
int i;
mirror_info_t *tmp;
printk("RAID10 conf printout:\n");
if (!conf) {
printk("(!conf)\n");
return;
}
printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
conf->raid_disks);
for (i = 0; i < conf->raid_disks; i++) {
char b[BDEVNAME_SIZE];
tmp = conf->mirrors + i;
if (tmp->rdev)
printk(" disk %d, wo:%d, o:%d, dev:%s\n",
i, !test_bit(In_sync, &tmp->rdev->flags),
!test_bit(Faulty, &tmp->rdev->flags),
bdevname(tmp->rdev->bdev,b));
}
}
static void close_sync(conf_t *conf)
{
wait_barrier(conf);
allow_barrier(conf);
mempool_destroy(conf->r10buf_pool);
conf->r10buf_pool = NULL;
}
/* check if there are enough drives for
* every block to appear on atleast one
*/
static int enough(conf_t *conf)
{
int first = 0;
do {
int n = conf->copies;
int cnt = 0;
while (n--) {
if (conf->mirrors[first].rdev)
cnt++;
first = (first+1) % conf->raid_disks;
}
if (cnt == 0)
return 0;
} while (first != 0);
return 1;
}
static int raid10_spare_active(mddev_t *mddev)
{
int i;
conf_t *conf = mddev->private;
mirror_info_t *tmp;
/*
* Find all non-in_sync disks within the RAID10 configuration
* and mark them in_sync
*/
for (i = 0; i < conf->raid_disks; i++) {
tmp = conf->mirrors + i;
if (tmp->rdev
&& !test_bit(Faulty, &tmp->rdev->flags)
&& !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded--;
spin_unlock_irqrestore(&conf->device_lock, flags);
}
}
print_conf(conf);
return 0;
}
static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
{
conf_t *conf = mddev->private;
int found = 0;
int mirror;
mirror_info_t *p;
if (mddev->recovery_cp < MaxSector)
/* only hot-add to in-sync arrays, as recovery is
* very different from resync
*/
return 0;
if (!enough(conf))
return 0;
if (rdev->saved_raid_disk >= 0 &&
conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
mirror = rdev->saved_raid_disk;
else
mirror = 0;
for ( ; mirror < mddev->raid_disks; mirror++)
if ( !(p=conf->mirrors+mirror)->rdev) {
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
/* as we don't honour merge_bvec_fn, we must never risk
* violating it, so limit ->max_sector to one PAGE, as
* a one page request is never in violation.
*/
if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
mddev->queue->max_sectors > (PAGE_SIZE>>9))
mddev->queue->max_sectors = (PAGE_SIZE>>9);
p->head_position = 0;
rdev->raid_disk = mirror;
found = 1;
if (rdev->saved_raid_disk != mirror)
conf->fullsync = 1;
rcu_assign_pointer(p->rdev, rdev);
break;
}
print_conf(conf);
return found;
}
static int raid10_remove_disk(mddev_t *mddev, int number)
{
conf_t *conf = mddev->private;
int err = 0;
mdk_rdev_t *rdev;
mirror_info_t *p = conf->mirrors+ number;
print_conf(conf);
rdev = p->rdev;
if (rdev) {
if (test_bit(In_sync, &rdev->flags) ||
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_conf(conf);
return err;
}
static void end_sync_read(struct bio *bio, int error)
{
r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
conf_t *conf = mddev_to_conf(r10_bio->mddev);
int i,d;
for (i=0; i<conf->copies; i++)
if (r10_bio->devs[i].bio == bio)
break;
BUG_ON(i == conf->copies);
update_head_pos(i, r10_bio);
d = r10_bio->devs[i].devnum;
if (test_bit(BIO_UPTODATE, &bio->bi_flags))
set_bit(R10BIO_Uptodate, &r10_bio->state);
else {
atomic_add(r10_bio->sectors,
&conf->mirrors[d].rdev->corrected_errors);
if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
md_error(r10_bio->mddev,
conf->mirrors[d].rdev);
}
/* for reconstruct, we always reschedule after a read.
* for resync, only after all reads
*/
if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
atomic_dec_and_test(&r10_bio->remaining)) {
/* we have read all the blocks,
* do the comparison in process context in raid10d
*/
reschedule_retry(r10_bio);
}
rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
}
static void end_sync_write(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
mddev_t *mddev = r10_bio->mddev;
conf_t *conf = mddev_to_conf(mddev);
int i,d;
for (i = 0; i < conf->copies; i++)
if (r10_bio->devs[i].bio == bio)
break;
d = r10_bio->devs[i].devnum;
if (!uptodate)
md_error(mddev, conf->mirrors[d].rdev);
update_head_pos(i, r10_bio);
while (atomic_dec_and_test(&r10_bio->remaining)) {
if (r10_bio->master_bio == NULL) {
/* the primary of several recovery bios */
md_done_sync(mddev, r10_bio->sectors, 1);
put_buf(r10_bio);
break;
} else {
r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
put_buf(r10_bio);
r10_bio = r10_bio2;
}
}
rdev_dec_pending(conf->mirrors[d].rdev, mddev);
}
/*
* Note: sync and recover and handled very differently for raid10
* This code is for resync.
* For resync, we read through virtual addresses and read all blocks.
* If there is any error, we schedule a write. The lowest numbered
* drive is authoritative.
* However requests come for physical address, so we need to map.
* For every physical address there are raid_disks/copies virtual addresses,
* which is always are least one, but is not necessarly an integer.
* This means that a physical address can span multiple chunks, so we may
* have to submit multiple io requests for a single sync request.
*/
/*
* We check if all blocks are in-sync and only write to blocks that
* aren't in sync
*/
static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
{
conf_t *conf = mddev_to_conf(mddev);
int i, first;
struct bio *tbio, *fbio;
atomic_set(&r10_bio->remaining, 1);
/* find the first device with a block */
for (i=0; i<conf->copies; i++)
if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
break;
if (i == conf->copies)
goto done;
first = i;
fbio = r10_bio->devs[i].bio;
/* now find blocks with errors */
for (i=0 ; i < conf->copies ; i++) {
int j, d;
int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
tbio = r10_bio->devs[i].bio;
if (tbio->bi_end_io != end_sync_read)
continue;
if (i == first)
continue;
if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
/* We know that the bi_io_vec layout is the same for
* both 'first' and 'i', so we just compare them.
* All vec entries are PAGE_SIZE;
*/
for (j = 0; j < vcnt; j++)
if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
page_address(tbio->bi_io_vec[j].bv_page),
PAGE_SIZE))
break;
if (j == vcnt)
continue;
mddev->resync_mismatches += r10_bio->sectors;
}
if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
/* Don't fix anything. */
continue;
/* Ok, we need to write this bio
* First we need to fixup bv_offset, bv_len and
* bi_vecs, as the read request might have corrupted these
*/
tbio->bi_vcnt = vcnt;
tbio->bi_size = r10_bio->sectors << 9;
tbio->bi_idx = 0;
tbio->bi_phys_segments = 0;
tbio->bi_hw_segments = 0;
tbio->bi_hw_front_size = 0;
tbio->bi_hw_back_size = 0;
tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
tbio->bi_flags |= 1 << BIO_UPTODATE;
tbio->bi_next = NULL;
tbio->bi_rw = WRITE;
tbio->bi_private = r10_bio;
tbio->bi_sector = r10_bio->devs[i].addr;
for (j=0; j < vcnt ; j++) {
tbio->bi_io_vec[j].bv_offset = 0;
tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
memcpy(page_address(tbio->bi_io_vec[j].bv_page),
page_address(fbio->bi_io_vec[j].bv_page),
PAGE_SIZE);
}
tbio->bi_end_io = end_sync_write;
d = r10_bio->devs[i].devnum;
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
atomic_inc(&r10_bio->remaining);
md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
generic_make_request(tbio);
}
done:
if (atomic_dec_and_test(&r10_bio->remaining)) {
md_done_sync(mddev, r10_bio->sectors, 1);
put_buf(r10_bio);
}
}
/*
* Now for the recovery code.
* Recovery happens across physical sectors.
* We recover all non-is_sync drives by finding the virtual address of
* each, and then choose a working drive that also has that virt address.
* There is a separate r10_bio for each non-in_sync drive.
* Only the first two slots are in use. The first for reading,
* The second for writing.
*
*/
static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
{
conf_t *conf = mddev_to_conf(mddev);
int i, d;
struct bio *bio, *wbio;
/* move the pages across to the second bio
* and submit the write request
*/
bio = r10_bio->devs[0].bio;
wbio = r10_bio->devs[1].bio;
for (i=0; i < wbio->bi_vcnt; i++) {
struct page *p = bio->bi_io_vec[i].bv_page;
bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
wbio->bi_io_vec[i].bv_page = p;
}
d = r10_bio->devs[1].devnum;
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
if (test_bit(R10BIO_Uptodate, &r10_bio->state))
generic_make_request(wbio);
else
bio_endio(wbio, -EIO);
}
/*
* This is a kernel thread which:
*
* 1. Retries failed read operations on working mirrors.
* 2. Updates the raid superblock when problems encounter.
* 3. Performs writes following reads for array synchronising.
*/
static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
{
int sect = 0; /* Offset from r10_bio->sector */
int sectors = r10_bio->sectors;
mdk_rdev_t*rdev;
while(sectors) {
int s = sectors;
int sl = r10_bio->read_slot;
int success = 0;
int start;
if (s > (PAGE_SIZE>>9))
s = PAGE_SIZE >> 9;
rcu_read_lock();
do {
int d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
test_bit(In_sync, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
success = sync_page_io(rdev->bdev,
r10_bio->devs[sl].addr +
sect + rdev->data_offset,
s<<9,
conf->tmppage, READ);
rdev_dec_pending(rdev, mddev);
rcu_read_lock();
if (success)
break;
}
sl++;
if (sl == conf->copies)
sl = 0;
} while (!success && sl != r10_bio->read_slot);
rcu_read_unlock();
if (!success) {
/* Cannot read from anywhere -- bye bye array */
int dn = r10_bio->devs[r10_bio->read_slot].devnum;
md_error(mddev, conf->mirrors[dn].rdev);
break;
}
start = sl;
/* write it back and re-read */
rcu_read_lock();
while (sl != r10_bio->read_slot) {
int d;
if (sl==0)
sl = conf->copies;
sl--;
d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
test_bit(In_sync, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
atomic_add(s, &rdev->corrected_errors);
if (sync_page_io(rdev->bdev,
r10_bio->devs[sl].addr +
sect + rdev->data_offset,
s<<9, conf->tmppage, WRITE)
== 0)
/* Well, this device is dead */
md_error(mddev, rdev);
rdev_dec_pending(rdev, mddev);
rcu_read_lock();
}
}
sl = start;
while (sl != r10_bio->read_slot) {
int d;
if (sl==0)
sl = conf->copies;
sl--;
d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
test_bit(In_sync, &rdev->flags)) {
char b[BDEVNAME_SIZE];
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
if (sync_page_io(rdev->bdev,
r10_bio->devs[sl].addr +
sect + rdev->data_offset,
s<<9, conf->tmppage, READ) == 0)
/* Well, this device is dead */
md_error(mddev, rdev);
else
printk(KERN_INFO
"raid10:%s: read error corrected"
" (%d sectors at %llu on %s)\n",
mdname(mddev), s,
(unsigned long long)(sect+
rdev->data_offset),
bdevname(rdev->bdev, b));
rdev_dec_pending(rdev, mddev);
rcu_read_lock();
}
}
rcu_read_unlock();
sectors -= s;
sect += s;
}
}
static void raid10d(mddev_t *mddev)
{
r10bio_t *r10_bio;
struct bio *bio;
unsigned long flags;
conf_t *conf = mddev_to_conf(mddev);
struct list_head *head = &conf->retry_list;
int unplug=0;
mdk_rdev_t *rdev;
md_check_recovery(mddev);
for (;;) {
char b[BDEVNAME_SIZE];
unplug += flush_pending_writes(conf);
spin_lock_irqsave(&conf->device_lock, flags);
if (list_empty(head)) {
spin_unlock_irqrestore(&conf->device_lock, flags);
break;
}
r10_bio = list_entry(head->prev, r10bio_t, retry_list);
list_del(head->prev);
conf->nr_queued--;
spin_unlock_irqrestore(&conf->device_lock, flags);
mddev = r10_bio->mddev;
conf = mddev_to_conf(mddev);
if (test_bit(R10BIO_IsSync, &r10_bio->state)) {
sync_request_write(mddev, r10_bio);
unplug = 1;
} else if (test_bit(R10BIO_IsRecover, &r10_bio->state)) {
recovery_request_write(mddev, r10_bio);
unplug = 1;
} else {
int mirror;
/* we got a read error. Maybe the drive is bad. Maybe just
* the block and we can fix it.
* We freeze all other IO, and try reading the block from
* other devices. When we find one, we re-write
* and check it that fixes the read error.
* This is all done synchronously while the array is
* frozen.
*/
if (mddev->ro == 0) {
freeze_array(conf);
fix_read_error(conf, mddev, r10_bio);
unfreeze_array(conf);
}
bio = r10_bio->devs[r10_bio->read_slot].bio;
r10_bio->devs[r10_bio->read_slot].bio =
mddev->ro ? IO_BLOCKED : NULL;
mirror = read_balance(conf, r10_bio);
if (mirror == -1) {
printk(KERN_ALERT "raid10: %s: unrecoverable I/O"
" read error for block %llu\n",
bdevname(bio->bi_bdev,b),
(unsigned long long)r10_bio->sector);
raid_end_bio_io(r10_bio);
bio_put(bio);
} else {
const int do_sync = bio_sync(r10_bio->master_bio);
bio_put(bio);
rdev = conf->mirrors[mirror].rdev;
if (printk_ratelimit())
printk(KERN_ERR "raid10: %s: redirecting sector %llu to"
" another mirror\n",
bdevname(rdev->bdev,b),
(unsigned long long)r10_bio->sector);
bio = bio_clone(r10_bio->master_bio, GFP_NOIO);
r10_bio->devs[r10_bio->read_slot].bio = bio;
bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
+ rdev->data_offset;
bio->bi_bdev = rdev->bdev;
bio->bi_rw = READ | do_sync;
bio->bi_private = r10_bio;
bio->bi_end_io = raid10_end_read_request;
unplug = 1;
generic_make_request(bio);
}
}
}
if (unplug)
unplug_slaves(mddev);
}
static int init_resync(conf_t *conf)
{
int buffs;
buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
BUG_ON(conf->r10buf_pool);
conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
if (!conf->r10buf_pool)
return -ENOMEM;
conf->next_resync = 0;
return 0;
}
/*
* perform a "sync" on one "block"
*
* We need to make sure that no normal I/O request - particularly write
* requests - conflict with active sync requests.
*
* This is achieved by tracking pending requests and a 'barrier' concept
* that can be installed to exclude normal IO requests.
*
* Resync and recovery are handled very differently.
* We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
*
* For resync, we iterate over virtual addresses, read all copies,
* and update if there are differences. If only one copy is live,
* skip it.
* For recovery, we iterate over physical addresses, read a good
* value for each non-in_sync drive, and over-write.
*
* So, for recovery we may have several outstanding complex requests for a
* given address, one for each out-of-sync device. We model this by allocating
* a number of r10_bio structures, one for each out-of-sync device.
* As we setup these structures, we collect all bio's together into a list
* which we then process collectively to add pages, and then process again
* to pass to generic_make_request.
*
* The r10_bio structures are linked using a borrowed master_bio pointer.
* This link is counted in ->remaining. When the r10_bio that points to NULL
* has its remaining count decremented to 0, the whole complex operation
* is complete.
*
*/
static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
{
conf_t *conf = mddev_to_conf(mddev);
r10bio_t *r10_bio;
struct bio *biolist = NULL, *bio;
sector_t max_sector, nr_sectors;
int disk;
int i;
int max_sync;
int sync_blocks;
sector_t sectors_skipped = 0;
int chunks_skipped = 0;
if (!conf->r10buf_pool)
if (init_resync(conf))
return 0;
skipped:
max_sector = mddev->size << 1;
if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
max_sector = mddev->resync_max_sectors;
if (sector_nr >= max_sector) {
/* If we aborted, we need to abort the
* sync on the 'current' bitmap chucks (there can
* be several when recovering multiple devices).
* as we may have started syncing it but not finished.
* We can find the current address in
* mddev->curr_resync, but for recovery,
* we need to convert that to several
* virtual addresses.
*/
if (mddev->curr_resync < max_sector) { /* aborted */
if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
&sync_blocks, 1);
else for (i=0; i<conf->raid_disks; i++) {
sector_t sect =
raid10_find_virt(conf, mddev->curr_resync, i);
bitmap_end_sync(mddev->bitmap, sect,
&sync_blocks, 1);
}
} else /* completed sync */
conf->fullsync = 0;
bitmap_close_sync(mddev->bitmap);
close_sync(conf);
*skipped = 1;
return sectors_skipped;
}
if (chunks_skipped >= conf->raid_disks) {
/* if there has been nothing to do on any drive,
* then there is nothing to do at all..
*/
*skipped = 1;
return (max_sector - sector_nr) + sectors_skipped;
}
if (max_sector > mddev->resync_max)
max_sector = mddev->resync_max; /* Don't do IO beyond here */
/* make sure whole request will fit in a chunk - if chunks
* are meaningful
*/
if (conf->near_copies < conf->raid_disks &&
max_sector > (sector_nr | conf->chunk_mask))
max_sector = (sector_nr | conf->chunk_mask) + 1;
/*
* If there is non-resync activity waiting for us then
* put in a delay to throttle resync.
*/
if (!go_faster && conf->nr_waiting)
msleep_interruptible(1000);
bitmap_cond_end_sync(mddev->bitmap, sector_nr);
/* Again, very different code for resync and recovery.
* Both must result in an r10bio with a list of bios that
* have bi_end_io, bi_sector, bi_bdev set,
* and bi_private set to the r10bio.
* For recovery, we may actually create several r10bios
* with 2 bios in each, that correspond to the bios in the main one.
* In this case, the subordinate r10bios link back through a
* borrowed master_bio pointer, and the counter in the master
* includes a ref from each subordinate.
*/
/* First, we decide what to do and set ->bi_end_io
* To end_sync_read if we want to read, and
* end_sync_write if we will want to write.
*/
max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
/* recovery... the complicated one */
int i, j, k;
r10_bio = NULL;
for (i=0 ; i<conf->raid_disks; i++)
if (conf->mirrors[i].rdev &&
!test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
int still_degraded = 0;
/* want to reconstruct this device */
r10bio_t *rb2 = r10_bio;
sector_t sect = raid10_find_virt(conf, sector_nr, i);
int must_sync;
/* Unless we are doing a full sync, we only need
* to recover the block if it is set in the bitmap
*/
must_sync = bitmap_start_sync(mddev->bitmap, sect,
&sync_blocks, 1);
if (sync_blocks < max_sync)
max_sync = sync_blocks;
if (!must_sync &&
!conf->fullsync) {
/* yep, skip the sync_blocks here, but don't assume
* that there will never be anything to do here
*/
chunks_skipped = -1;
continue;
}
r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
raise_barrier(conf, rb2 != NULL);
atomic_set(&r10_bio->remaining, 0);
r10_bio->master_bio = (struct bio*)rb2;
if (rb2)
atomic_inc(&rb2->remaining);
r10_bio->mddev = mddev;
set_bit(R10BIO_IsRecover, &r10_bio->state);
r10_bio->sector = sect;
raid10_find_phys(conf, r10_bio);
/* Need to check if this section will still be
* degraded
*/
for (j=0; j<conf->copies;j++) {
int d = r10_bio->devs[j].devnum;
if (conf->mirrors[d].rdev == NULL ||
test_bit(Faulty, &conf->mirrors[d].rdev->flags)) {
still_degraded = 1;
break;
}
}
must_sync = bitmap_start_sync(mddev->bitmap, sect,
&sync_blocks, still_degraded);
for (j=0; j<conf->copies;j++) {
int d = r10_bio->devs[j].devnum;
if (conf->mirrors[d].rdev &&
test_bit(In_sync, &conf->mirrors[d].rdev->flags)) {
/* This is where we read from */
bio = r10_bio->devs[0].bio;
bio->bi_next = biolist;
biolist = bio;
bio->bi_private = r10_bio;
bio->bi_end_io = end_sync_read;
bio->bi_rw = READ;
bio->bi_sector = r10_bio->devs[j].addr +
conf->mirrors[d].rdev->data_offset;
bio->bi_bdev = conf->mirrors[d].rdev->bdev;
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
atomic_inc(&r10_bio->remaining);
/* and we write to 'i' */
for (k=0; k<conf->copies; k++)
if (r10_bio->devs[k].devnum == i)
break;
BUG_ON(k == conf->copies);
bio = r10_bio->devs[1].bio;
bio->bi_next = biolist;
biolist = bio;
bio->bi_private = r10_bio;
bio->bi_end_io = end_sync_write;
bio->bi_rw = WRITE;
bio->bi_sector = r10_bio->devs[k].addr +
conf->mirrors[i].rdev->data_offset;
bio->bi_bdev = conf->mirrors[i].rdev->bdev;
r10_bio->devs[0].devnum = d;
r10_bio->devs[1].devnum = i;
break;
}
}
if (j == conf->copies) {
/* Cannot recover, so abort the recovery */
put_buf(r10_bio);
if (rb2)
atomic_dec(&rb2->remaining);
r10_bio = rb2;
if (!test_and_set_bit(MD_RECOVERY_ERR, &mddev->recovery))
printk(KERN_INFO "raid10: %s: insufficient working devices for recovery.\n",
mdname(mddev));
break;
}
}
if (biolist == NULL) {
while (r10_bio) {
r10bio_t *rb2 = r10_bio;
r10_bio = (r10bio_t*) rb2->master_bio;
rb2->master_bio = NULL;
put_buf(rb2);
}
goto giveup;
}
} else {
/* resync. Schedule a read for every block at this virt offset */
int count = 0;
if (!bitmap_start_sync(mddev->bitmap, sector_nr,
&sync_blocks, mddev->degraded) &&
!conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
/* We can skip this block */
*skipped = 1;
return sync_blocks + sectors_skipped;
}
if (sync_blocks < max_sync)
max_sync = sync_blocks;
r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
r10_bio->mddev = mddev;
atomic_set(&r10_bio->remaining, 0);
raise_barrier(conf, 0);
conf->next_resync = sector_nr;
r10_bio->master_bio = NULL;
r10_bio->sector = sector_nr;
set_bit(R10BIO_IsSync, &r10_bio->state);
raid10_find_phys(conf, r10_bio);
r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
for (i=0; i<conf->copies; i++) {
int d = r10_bio->devs[i].devnum;
bio = r10_bio->devs[i].bio;
bio->bi_end_io = NULL;
clear_bit(BIO_UPTODATE, &bio->bi_flags);
if (conf->mirrors[d].rdev == NULL ||
test_bit(Faulty, &conf->mirrors[d].rdev->flags))
continue;
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
atomic_inc(&r10_bio->remaining);
bio->bi_next = biolist;
biolist = bio;
bio->bi_private = r10_bio;
bio->bi_end_io = end_sync_read;
bio->bi_rw = READ;
bio->bi_sector = r10_bio->devs[i].addr +
conf->mirrors[d].rdev->data_offset;
bio->bi_bdev = conf->mirrors[d].rdev->bdev;
count++;
}
if (count < 2) {
for (i=0; i<conf->copies; i++) {
int d = r10_bio->devs[i].devnum;
if (r10_bio->devs[i].bio->bi_end_io)
rdev_dec_pending(conf->mirrors[d].rdev, mddev);
}
put_buf(r10_bio);
biolist = NULL;
goto giveup;
}
}
for (bio = biolist; bio ; bio=bio->bi_next) {
bio->bi_flags &= ~(BIO_POOL_MASK - 1);
if (bio->bi_end_io)
bio->bi_flags |= 1 << BIO_UPTODATE;
bio->bi_vcnt = 0;
bio->bi_idx = 0;
bio->bi_phys_segments = 0;
bio->bi_hw_segments = 0;
bio->bi_size = 0;
}
nr_sectors = 0;
if (sector_nr + max_sync < max_sector)
max_sector = sector_nr + max_sync;
do {
struct page *page;
int len = PAGE_SIZE;
disk = 0;
if (sector_nr + (len>>9) > max_sector)
len = (max_sector - sector_nr) << 9;
if (len == 0)
break;
for (bio= biolist ; bio ; bio=bio->bi_next) {
page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
if (bio_add_page(bio, page, len, 0) == 0) {
/* stop here */
struct bio *bio2;
bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
for (bio2 = biolist; bio2 && bio2 != bio; bio2 = bio2->bi_next) {
/* remove last page from this bio */
bio2->bi_vcnt--;
bio2->bi_size -= len;
bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
}
goto bio_full;
}
disk = i;
}
nr_sectors += len>>9;
sector_nr += len>>9;
} while (biolist->bi_vcnt < RESYNC_PAGES);
bio_full:
r10_bio->sectors = nr_sectors;
while (biolist) {
bio = biolist;
biolist = biolist->bi_next;
bio->bi_next = NULL;
r10_bio = bio->bi_private;
r10_bio->sectors = nr_sectors;
if (bio->bi_end_io == end_sync_read) {
md_sync_acct(bio->bi_bdev, nr_sectors);
generic_make_request(bio);
}
}
if (sectors_skipped)
/* pretend they weren't skipped, it makes
* no important difference in this case
*/
md_done_sync(mddev, sectors_skipped, 1);
return sectors_skipped + nr_sectors;
giveup:
/* There is nowhere to write, so all non-sync
* drives must be failed, so try the next chunk...
*/
{
sector_t sec = max_sector - sector_nr;
sectors_skipped += sec;
chunks_skipped ++;
sector_nr = max_sector;
goto skipped;
}
}
static int run(mddev_t *mddev)
{
conf_t *conf;
int i, disk_idx;
mirror_info_t *disk;
mdk_rdev_t *rdev;
struct list_head *tmp;
int nc, fc, fo;
sector_t stride, size;
if (mddev->chunk_size == 0) {
printk(KERN_ERR "md/raid10: non-zero chunk size required.\n");
return -EINVAL;
}
nc = mddev->layout & 255;
fc = (mddev->layout >> 8) & 255;
fo = mddev->layout & (1<<16);
if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
(mddev->layout >> 17)) {
printk(KERN_ERR "raid10: %s: unsupported raid10 layout: 0x%8x\n",
mdname(mddev), mddev->layout);
goto out;
}
/*
* copy the already verified devices into our private RAID10
* bookkeeping area. [whatever we allocate in run(),
* should be freed in stop()]
*/
conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
mddev->private = conf;
if (!conf) {
printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
mdname(mddev));
goto out;
}
conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
GFP_KERNEL);
if (!conf->mirrors) {
printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
mdname(mddev));
goto out_free_conf;
}
conf->tmppage = alloc_page(GFP_KERNEL);
if (!conf->tmppage)
goto out_free_conf;
conf->mddev = mddev;
conf->raid_disks = mddev->raid_disks;
conf->near_copies = nc;
conf->far_copies = fc;
conf->copies = nc*fc;
conf->far_offset = fo;
conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;
conf->chunk_shift = ffz(~mddev->chunk_size) - 9;
size = mddev->size >> (conf->chunk_shift-1);
sector_div(size, fc);
size = size * conf->raid_disks;
sector_div(size, nc);
/* 'size' is now the number of chunks in the array */
/* calculate "used chunks per device" in 'stride' */
stride = size * conf->copies;
/* We need to round up when dividing by raid_disks to
* get the stride size.
*/
stride += conf->raid_disks - 1;
sector_div(stride, conf->raid_disks);
mddev->size = stride << (conf->chunk_shift-1);
if (fo)
stride = 1;
else
sector_div(stride, fc);
conf->stride = stride << conf->chunk_shift;
conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
r10bio_pool_free, conf);
if (!conf->r10bio_pool) {
printk(KERN_ERR "raid10: couldn't allocate memory for %s\n",
mdname(mddev));
goto out_free_conf;
}
rdev_for_each(rdev, tmp, mddev) {
disk_idx = rdev->raid_disk;
if (disk_idx >= mddev->raid_disks
|| disk_idx < 0)
continue;
disk = conf->mirrors + disk_idx;
disk->rdev = rdev;
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
/* as we don't honour merge_bvec_fn, we must never risk
* violating it, so limit ->max_sector to one PAGE, as
* a one page request is never in violation.
*/
if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
mddev->queue->max_sectors > (PAGE_SIZE>>9))
mddev->queue->max_sectors = (PAGE_SIZE>>9);
disk->head_position = 0;
}
spin_lock_init(&conf->device_lock);
INIT_LIST_HEAD(&conf->retry_list);
spin_lock_init(&conf->resync_lock);
init_waitqueue_head(&conf->wait_barrier);
/* need to check that every block has at least one working mirror */
if (!enough(conf)) {
printk(KERN_ERR "raid10: not enough operational mirrors for %s\n",
mdname(mddev));
goto out_free_conf;
}
mddev->degraded = 0;
for (i = 0; i < conf->raid_disks; i++) {
disk = conf->mirrors + i;
if (!disk->rdev ||
!test_bit(In_sync, &disk->rdev->flags)) {
disk->head_position = 0;
mddev->degraded++;
}
}
mddev->thread = md_register_thread(raid10d, mddev, "%s_raid10");
if (!mddev->thread) {
printk(KERN_ERR
"raid10: couldn't allocate thread for %s\n",
mdname(mddev));
goto out_free_conf;
}
printk(KERN_INFO
"raid10: raid set %s active with %d out of %d devices\n",
mdname(mddev), mddev->raid_disks - mddev->degraded,
mddev->raid_disks);
/*
* Ok, everything is just fine now
*/
mddev->array_size = size << (conf->chunk_shift-1);
mddev->resync_max_sectors = size << conf->chunk_shift;
mddev->queue->unplug_fn = raid10_unplug;
mddev->queue->backing_dev_info.congested_fn = raid10_congested;
mddev->queue->backing_dev_info.congested_data = mddev;
/* Calculate max read-ahead size.
* We need to readahead at least twice a whole stripe....
* maybe...
*/
{
int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
stripe /= conf->near_copies;
if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
mddev->queue->backing_dev_info.ra_pages = 2* stripe;
}
if (conf->near_copies < mddev->raid_disks)
blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
return 0;
out_free_conf:
if (conf->r10bio_pool)
mempool_destroy(conf->r10bio_pool);
safe_put_page(conf->tmppage);
kfree(conf->mirrors);
kfree(conf);
mddev->private = NULL;
out:
return -EIO;
}
static int stop(mddev_t *mddev)
{
conf_t *conf = mddev_to_conf(mddev);
md_unregister_thread(mddev->thread);
mddev->thread = NULL;
blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
if (conf->r10bio_pool)
mempool_destroy(conf->r10bio_pool);
kfree(conf->mirrors);
kfree(conf);
mddev->private = NULL;
return 0;
}
static void raid10_quiesce(mddev_t *mddev, int state)
{
conf_t *conf = mddev_to_conf(mddev);
switch(state) {
case 1:
raise_barrier(conf, 0);
break;
case 0:
lower_barrier(conf);
break;
}
if (mddev->thread) {
if (mddev->bitmap)
mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
else
mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
md_wakeup_thread(mddev->thread);
}
}
static struct mdk_personality raid10_personality =
{
.name = "raid10",
.level = 10,
.owner = THIS_MODULE,
.make_request = make_request,
.run = run,
.stop = stop,
.status = status,
.error_handler = error,
.hot_add_disk = raid10_add_disk,
.hot_remove_disk= raid10_remove_disk,
.spare_active = raid10_spare_active,
.sync_request = sync_request,
.quiesce = raid10_quiesce,
};
static int __init raid_init(void)
{
return register_md_personality(&raid10_personality);
}
static void raid_exit(void)
{
unregister_md_personality(&raid10_personality);
}
module_init(raid_init);
module_exit(raid_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("md-personality-9"); /* RAID10 */
MODULE_ALIAS("md-raid10");
MODULE_ALIAS("md-level-10");
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