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raid1.c
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/*
* raid1.c : Multiple Devices driver for Linux
*
* Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
*
* Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
*
* RAID-1 management functions.
*
* Better read-balancing code written by Mika Kuoppala <[email protected]>, 2000
*
* Fixes to reconstruction by Jakob Østergaard" <[email protected]>
* Various fixes by Neil Brown <[email protected]>
*
* Changes by Peter T. Breuer <[email protected]> 31/1/2003 to support
* bitmapped intelligence in resync:
*
* - bitmap marked during normal i/o
* - bitmap used to skip nondirty blocks during sync
*
* Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
* - persistent bitmap code
*
* 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/slab.h>
#include <linux/delay.h>
#include <linux/blkdev.h>
#include <linux/seq_file.h>
#include "md.h"
#include "raid1.h"
#include "bitmap.h"
#define DEBUG 0
#if DEBUG
#define PRINTK(x...) printk(x)
#else
#define PRINTK(x...)
#endif
/*
* Number of guaranteed r1bios in case of extreme VM load:
*/
#define NR_RAID1_BIOS 256
static void allow_barrier(conf_t *conf);
static void lower_barrier(conf_t *conf);
static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
{
struct pool_info *pi = data;
int size = offsetof(r1bio_t, bios[pi->raid_disks]);
/* allocate a r1bio with room for raid_disks entries in the bios array */
return kzalloc(size, gfp_flags);
}
static void r1bio_pool_free(void *r1_bio, void *data)
{
kfree(r1_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)
static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
{
struct pool_info *pi = data;
struct page *page;
r1bio_t *r1_bio;
struct bio *bio;
int i, j;
r1_bio = r1bio_pool_alloc(gfp_flags, pi);
if (!r1_bio)
return NULL;
/*
* Allocate bios : 1 for reading, n-1 for writing
*/
for (j = pi->raid_disks ; j-- ; ) {
bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
if (!bio)
goto out_free_bio;
r1_bio->bios[j] = bio;
}
/*
* Allocate RESYNC_PAGES data pages and attach them to
* the first bio.
* If this is a user-requested check/repair, allocate
* RESYNC_PAGES for each bio.
*/
if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
j = pi->raid_disks;
else
j = 1;
while(j--) {
bio = r1_bio->bios[j];
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;
bio->bi_vcnt = i+1;
}
}
/* If not user-requests, copy the page pointers to all bios */
if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
for (i=0; i<RESYNC_PAGES ; i++)
for (j=1; j<pi->raid_disks; j++)
r1_bio->bios[j]->bi_io_vec[i].bv_page =
r1_bio->bios[0]->bi_io_vec[i].bv_page;
}
r1_bio->master_bio = NULL;
return r1_bio;
out_free_pages:
for (j=0 ; j < pi->raid_disks; j++)
for (i=0; i < r1_bio->bios[j]->bi_vcnt ; i++)
put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
j = -1;
out_free_bio:
while ( ++j < pi->raid_disks )
bio_put(r1_bio->bios[j]);
r1bio_pool_free(r1_bio, data);
return NULL;
}
static void r1buf_pool_free(void *__r1_bio, void *data)
{
struct pool_info *pi = data;
int i,j;
r1bio_t *r1bio = __r1_bio;
for (i = 0; i < RESYNC_PAGES; i++)
for (j = pi->raid_disks; j-- ;) {
if (j == 0 ||
r1bio->bios[j]->bi_io_vec[i].bv_page !=
r1bio->bios[0]->bi_io_vec[i].bv_page)
safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
}
for (i=0 ; i < pi->raid_disks; i++)
bio_put(r1bio->bios[i]);
r1bio_pool_free(r1bio, data);
}
static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
{
int i;
for (i = 0; i < conf->raid_disks; i++) {
struct bio **bio = r1_bio->bios + i;
if (*bio && *bio != IO_BLOCKED)
bio_put(*bio);
*bio = NULL;
}
}
static void free_r1bio(r1bio_t *r1_bio)
{
conf_t *conf = r1_bio->mddev->private;
/*
* Wake up any possible resync thread that waits for the device
* to go idle.
*/
allow_barrier(conf);
put_all_bios(conf, r1_bio);
mempool_free(r1_bio, conf->r1bio_pool);
}
static void put_buf(r1bio_t *r1_bio)
{
conf_t *conf = r1_bio->mddev->private;
int i;
for (i=0; i<conf->raid_disks; i++) {
struct bio *bio = r1_bio->bios[i];
if (bio->bi_end_io)
rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
}
mempool_free(r1_bio, conf->r1buf_pool);
lower_barrier(conf);
}
static void reschedule_retry(r1bio_t *r1_bio)
{
unsigned long flags;
mddev_t *mddev = r1_bio->mddev;
conf_t *conf = mddev->private;
spin_lock_irqsave(&conf->device_lock, flags);
list_add(&r1_bio->retry_list, &conf->retry_list);
conf->nr_queued ++;
spin_unlock_irqrestore(&conf->device_lock, flags);
wake_up(&conf->wait_barrier);
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(r1bio_t *r1_bio)
{
struct bio *bio = r1_bio->master_bio;
/* if nobody has done the final endio yet, do it now */
if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
PRINTK(KERN_DEBUG "raid1: sync end %s on sectors %llu-%llu\n",
(bio_data_dir(bio) == WRITE) ? "write" : "read",
(unsigned long long) bio->bi_sector,
(unsigned long long) bio->bi_sector +
(bio->bi_size >> 9) - 1);
bio_endio(bio,
test_bit(R1BIO_Uptodate, &r1_bio->state) ? 0 : -EIO);
}
free_r1bio(r1_bio);
}
/*
* Update disk head position estimator based on IRQ completion info.
*/
static inline void update_head_pos(int disk, r1bio_t *r1_bio)
{
conf_t *conf = r1_bio->mddev->private;
conf->mirrors[disk].head_position =
r1_bio->sector + (r1_bio->sectors);
}
static void raid1_end_read_request(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r1bio_t *r1_bio = bio->bi_private;
int mirror;
conf_t *conf = r1_bio->mddev->private;
mirror = r1_bio->read_disk;
/*
* this branch is our 'one mirror IO has finished' event handler:
*/
update_head_pos(mirror, r1_bio);
if (uptodate)
set_bit(R1BIO_Uptodate, &r1_bio->state);
else {
/* If all other devices have failed, we want to return
* the error upwards rather than fail the last device.
* Here we redefine "uptodate" to mean "Don't want to retry"
*/
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
if (r1_bio->mddev->degraded == conf->raid_disks ||
(r1_bio->mddev->degraded == conf->raid_disks-1 &&
!test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
uptodate = 1;
spin_unlock_irqrestore(&conf->device_lock, flags);
}
if (uptodate)
raid_end_bio_io(r1_bio);
else {
/*
* oops, read error:
*/
char b[BDEVNAME_SIZE];
if (printk_ratelimit())
printk(KERN_ERR "md/raid1:%s: %s: rescheduling sector %llu\n",
mdname(conf->mddev),
bdevname(conf->mirrors[mirror].rdev->bdev,b), (unsigned long long)r1_bio->sector);
reschedule_retry(r1_bio);
}
rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
}
static void r1_bio_write_done(r1bio_t *r1_bio, int vcnt, struct bio_vec *bv,
int behind)
{
if (atomic_dec_and_test(&r1_bio->remaining))
{
/* it really is the end of this request */
if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
/* free extra copy of the data pages */
int i = vcnt;
while (i--)
safe_put_page(bv[i].bv_page);
}
/* clear the bitmap if all writes complete successfully */
bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
r1_bio->sectors,
!test_bit(R1BIO_Degraded, &r1_bio->state),
behind);
md_write_end(r1_bio->mddev);
raid_end_bio_io(r1_bio);
}
}
static void raid1_end_write_request(struct bio *bio, int error)
{
int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r1bio_t *r1_bio = bio->bi_private;
int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
conf_t *conf = r1_bio->mddev->private;
struct bio *to_put = NULL;
for (mirror = 0; mirror < conf->raid_disks; mirror++)
if (r1_bio->bios[mirror] == bio)
break;
/*
* 'one mirror IO has finished' event handler:
*/
r1_bio->bios[mirror] = NULL;
to_put = bio;
if (!uptodate) {
md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
/* an I/O failed, we can't clear the bitmap */
set_bit(R1BIO_Degraded, &r1_bio->state);
} else
/*
* Set R1BIO_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(R1BIO_Uptodate, &r1_bio->state);
update_head_pos(mirror, r1_bio);
if (behind) {
if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
atomic_dec(&r1_bio->behind_remaining);
/*
* In behind mode, we ACK the master bio once the I/O
* has safely reached all non-writemostly
* disks. Setting the Returned bit ensures that this
* gets done only once -- we don't ever want to return
* -EIO here, instead we'll wait
*/
if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
test_bit(R1BIO_Uptodate, &r1_bio->state)) {
/* Maybe we can return now */
if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
struct bio *mbio = r1_bio->master_bio;
PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
(unsigned long long) mbio->bi_sector,
(unsigned long long) mbio->bi_sector +
(mbio->bi_size >> 9) - 1);
bio_endio(mbio, 0);
}
}
}
rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
/*
* Let's see if all mirrored write operations have finished
* already.
*/
r1_bio_write_done(r1_bio, bio->bi_vcnt, bio->bi_io_vec, behind);
if (to_put)
bio_put(to_put);
}
/*
* 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.
*/
static int read_balance(conf_t *conf, r1bio_t *r1_bio)
{
const sector_t this_sector = r1_bio->sector;
const int sectors = r1_bio->sectors;
int new_disk = -1;
int start_disk;
int i;
sector_t new_distance, current_distance;
mdk_rdev_t *rdev;
int choose_first;
rcu_read_lock();
/*
* Check if we can balance. We can balance on the whole
* device if no resync is going on, or below the resync window.
* We take the first readable disk when above the resync window.
*/
retry:
if (conf->mddev->recovery_cp < MaxSector &&
(this_sector + sectors >= conf->next_resync)) {
choose_first = 1;
start_disk = 0;
} else {
choose_first = 0;
start_disk = conf->last_used;
}
/* make sure the disk is operational */
for (i = 0 ; i < conf->raid_disks ; i++) {
int disk = start_disk + i;
if (disk >= conf->raid_disks)
disk -= conf->raid_disks;
rdev = rcu_dereference(conf->mirrors[disk].rdev);
if (r1_bio->bios[disk] == IO_BLOCKED
|| rdev == NULL
|| !test_bit(In_sync, &rdev->flags))
continue;
new_disk = disk;
if (!test_bit(WriteMostly, &rdev->flags))
break;
}
if (new_disk < 0 || choose_first)
goto rb_out;
/*
* Don't change to another disk for sequential reads:
*/
if (conf->next_seq_sect == this_sector)
goto rb_out;
if (this_sector == conf->mirrors[new_disk].head_position)
goto rb_out;
current_distance = abs(this_sector
- conf->mirrors[new_disk].head_position);
/* look for a better disk - i.e. head is closer */
start_disk = new_disk;
for (i = 1; i < conf->raid_disks; i++) {
int disk = start_disk + 1;
if (disk >= conf->raid_disks)
disk -= conf->raid_disks;
rdev = rcu_dereference(conf->mirrors[disk].rdev);
if (r1_bio->bios[disk] == IO_BLOCKED
|| rdev == NULL
|| !test_bit(In_sync, &rdev->flags)
|| test_bit(WriteMostly, &rdev->flags))
continue;
if (!atomic_read(&rdev->nr_pending)) {
new_disk = disk;
break;
}
new_distance = abs(this_sector - conf->mirrors[disk].head_position);
if (new_distance < current_distance) {
current_distance = new_distance;
new_disk = disk;
}
}
rb_out:
if (new_disk >= 0) {
rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
if (!rdev)
goto retry;
atomic_inc(&rdev->nr_pending);
if (!test_bit(In_sync, &rdev->flags)) {
/* cannot risk returning a device that failed
* before we inc'ed nr_pending
*/
rdev_dec_pending(rdev, conf->mddev);
goto retry;
}
conf->next_seq_sect = this_sector + sectors;
conf->last_used = new_disk;
}
rcu_read_unlock();
return new_disk;
}
static int raid1_congested(void *data, int bits)
{
mddev_t *mddev = data;
conf_t *conf = mddev->private;
int i, ret = 0;
if (mddev_congested(mddev, bits))
return 1;
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)) {
struct request_queue *q = bdev_get_queue(rdev->bdev);
/* Note the '|| 1' - when read_balance prefers
* non-congested targets, it can be removed
*/
if ((bits & (1<<BDI_async_congested)) || 1)
ret |= bdi_congested(&q->backing_dev_info, bits);
else
ret &= bdi_congested(&q->backing_dev_info, bits);
}
}
rcu_read_unlock();
return ret;
}
static void flush_pending_writes(conf_t *conf)
{
/* Any writes that have been queued but are awaiting
* bitmap updates get flushed here.
*/
spin_lock_irq(&conf->device_lock);
if (conf->pending_bio_list.head) {
struct bio *bio;
bio = bio_list_get(&conf->pending_bio_list);
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;
}
} else
spin_unlock_irq(&conf->device_lock);
}
static void md_kick_device(mddev_t *mddev)
{
blk_flush_plug(current);
md_wakeup_thread(mddev->thread);
}
/* 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)
{
spin_lock_irq(&conf->resync_lock);
/* Wait until no block IO is waiting */
wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
conf->resync_lock, md_kick_device(conf->mddev));
/* block any new IO from starting */
conf->barrier++;
/* Now wait for all pending IO to complete */
wait_event_lock_irq(conf->wait_barrier,
!conf->nr_pending && conf->barrier < RESYNC_DEPTH,
conf->resync_lock, md_kick_device(conf->mddev));
spin_unlock_irq(&conf->resync_lock);
}
static void lower_barrier(conf_t *conf)
{
unsigned long flags;
BUG_ON(conf->barrier <= 0);
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,
md_kick_device(conf->mddev));
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 quite.
* 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);
md_kick_device(conf->mddev); }));
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);
}
/* duplicate the data pages for behind I/O
* We return a list of bio_vec rather than just page pointers
* as it makes freeing easier
*/
static struct bio_vec *alloc_behind_pages(struct bio *bio)
{
int i;
struct bio_vec *bvec;
struct bio_vec *pages = kzalloc(bio->bi_vcnt * sizeof(struct bio_vec),
GFP_NOIO);
if (unlikely(!pages))
goto do_sync_io;
bio_for_each_segment(bvec, bio, i) {
pages[i].bv_page = alloc_page(GFP_NOIO);
if (unlikely(!pages[i].bv_page))
goto do_sync_io;
memcpy(kmap(pages[i].bv_page) + bvec->bv_offset,
kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len);
kunmap(pages[i].bv_page);
kunmap(bvec->bv_page);
}
return pages;
do_sync_io:
if (pages)
for (i = 0; i < bio->bi_vcnt && pages[i].bv_page; i++)
put_page(pages[i].bv_page);
kfree(pages);
PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
return NULL;
}
static int make_request(mddev_t *mddev, struct bio * bio)
{
conf_t *conf = mddev->private;
mirror_info_t *mirror;
r1bio_t *r1_bio;
struct bio *read_bio;
int i, targets = 0, disks;
struct bitmap *bitmap;
unsigned long flags;
struct bio_vec *behind_pages = NULL;
const int rw = bio_data_dir(bio);
const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
mdk_rdev_t *blocked_rdev;
/*
* 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.
*/
md_write_start(mddev, bio); /* wait on superblock update early */
if (bio_data_dir(bio) == WRITE &&
bio->bi_sector + bio->bi_size/512 > mddev->suspend_lo &&
bio->bi_sector < mddev->suspend_hi) {
/* As the suspend_* range is controlled by
* userspace, we want an interruptible
* wait.
*/
DEFINE_WAIT(w);
for (;;) {
flush_signals(current);
prepare_to_wait(&conf->wait_barrier,
&w, TASK_INTERRUPTIBLE);
if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
bio->bi_sector >= mddev->suspend_hi)
break;
schedule();
}
finish_wait(&conf->wait_barrier, &w);
}
wait_barrier(conf);
bitmap = mddev->bitmap;
/*
* make_request() can abort the operation when READA is being
* used and no empty request is available.
*
*/
r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
r1_bio->master_bio = bio;
r1_bio->sectors = bio->bi_size >> 9;
r1_bio->state = 0;
r1_bio->mddev = mddev;
r1_bio->sector = bio->bi_sector;
if (rw == READ) {
/*
* read balancing logic:
*/
int rdisk = read_balance(conf, r1_bio);
if (rdisk < 0) {
/* couldn't find anywhere to read from */
raid_end_bio_io(r1_bio);
return 0;
}
mirror = conf->mirrors + rdisk;
if (test_bit(WriteMostly, &mirror->rdev->flags) &&
bitmap) {
/* Reading from a write-mostly device must
* take care not to over-take any writes
* that are 'behind'
*/
wait_event(bitmap->behind_wait,
atomic_read(&bitmap->behind_writes) == 0);
}
r1_bio->read_disk = rdisk;
read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
r1_bio->bios[rdisk] = read_bio;
read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
read_bio->bi_bdev = mirror->rdev->bdev;
read_bio->bi_end_io = raid1_end_read_request;
read_bio->bi_rw = READ | do_sync;
read_bio->bi_private = r1_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
*/
disks = conf->raid_disks;
retry_write:
blocked_rdev = NULL;
rcu_read_lock();
for (i = 0; i < disks; i++) {
mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
atomic_inc(&rdev->nr_pending);
blocked_rdev = rdev;
break;
}
if (rdev && !test_bit(Faulty, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
if (test_bit(Faulty, &rdev->flags)) {
rdev_dec_pending(rdev, mddev);
r1_bio->bios[i] = NULL;
} else {
r1_bio->bios[i] = bio;
targets++;
}
} else
r1_bio->bios[i] = NULL;
}
rcu_read_unlock();
if (unlikely(blocked_rdev)) {
/* Wait for this device to become unblocked */
int j;
for (j = 0; j < i; j++)
if (r1_bio->bios[j])
rdev_dec_pending(conf->mirrors[j].rdev, mddev);
allow_barrier(conf);
md_wait_for_blocked_rdev(blocked_rdev, mddev);
wait_barrier(conf);
goto retry_write;
}
BUG_ON(targets == 0); /* we never fail the last device */
if (targets < conf->raid_disks) {
/* array is degraded, we will not clear the bitmap
* on I/O completion (see raid1_end_write_request) */
set_bit(R1BIO_Degraded, &r1_bio->state);
}
/* do behind I/O ?
* Not if there are too many, or cannot allocate memory,
* or a reader on WriteMostly is waiting for behind writes
* to flush */
if (bitmap &&
(atomic_read(&bitmap->behind_writes)
< mddev->bitmap_info.max_write_behind) &&
!waitqueue_active(&bitmap->behind_wait) &&
(behind_pages = alloc_behind_pages(bio)) != NULL)
set_bit(R1BIO_BehindIO, &r1_bio->state);
atomic_set(&r1_bio->remaining, 1);
atomic_set(&r1_bio->behind_remaining, 0);
bitmap_startwrite(bitmap, bio->bi_sector, r1_bio->sectors,
test_bit(R1BIO_BehindIO, &r1_bio->state));
for (i = 0; i < disks; i++) {
struct bio *mbio;
if (!r1_bio->bios[i])
continue;
mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
r1_bio->bios[i] = mbio;
mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
mbio->bi_end_io = raid1_end_write_request;
mbio->bi_rw = WRITE | do_flush_fua | do_sync;
mbio->bi_private = r1_bio;
if (behind_pages) {
struct bio_vec *bvec;
int j;
/* Yes, I really want the '__' version so that
* we clear any unused pointer in the io_vec, rather
* than leave them unchanged. This is important
* because when we come to free the pages, we won't
* know the original bi_idx, so we just free
* them all
*/
__bio_for_each_segment(bvec, mbio, j, 0)
bvec->bv_page = behind_pages[j].bv_page;
if (test_bit(WriteMostly, &conf->mirrors[i].rdev->flags))
atomic_inc(&r1_bio->behind_remaining);
}
atomic_inc(&r1_bio->remaining);
spin_lock_irqsave(&conf->device_lock, flags);
bio_list_add(&conf->pending_bio_list, mbio);
spin_unlock_irqrestore(&conf->device_lock, flags);
}
r1_bio_write_done(r1_bio, bio->bi_vcnt, behind_pages, behind_pages != NULL);
kfree(behind_pages); /* the behind pages are attached to the bios now */
/* In case raid1d snuck in to freeze_array */
wake_up(&conf->wait_barrier);
if (do_sync || !bitmap)
md_wakeup_thread(mddev->thread);
return 0;
}
static void status(struct seq_file *seq, mddev_t *mddev)
{
conf_t *conf = mddev->private;
int i;
seq_printf(seq, " [%d/%d] [", conf->raid_disks,
conf->raid_disks - mddev->degraded);
rcu_read_lock();
for (i = 0; i < conf->raid_disks; i++) {
mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
seq_printf(seq, "%s",
rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
}
rcu_read_unlock();
seq_printf(seq, "]");
}
static void error(mddev_t *mddev, mdk_rdev_t *rdev)
{
char b[BDEVNAME_SIZE];
conf_t *conf = mddev->private;
/*
* 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, act as though we were just a
* normal single drive.
* However don't try a recovery from this drive as
* it is very likely to fail.
*/
mddev->recovery_disabled = 1;
return;
}
if (test_and_clear_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
set_bit(Faulty, &rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
} else
set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
printk(KERN_ALERT
"md/raid1:%s: Disk failure on %s, disabling device.\n"
"md/raid1:%s: Operation continuing on %d devices.\n",
mdname(mddev), bdevname(rdev->bdev, b),
mdname(mddev), conf->raid_disks - mddev->degraded);
}
static void print_conf(conf_t *conf)
{
int i;
printk(KERN_DEBUG "RAID1 conf printout:\n");
if (!conf) {
printk(KERN_DEBUG "(!conf)\n");