linux/drivers/md/dm.c
Alan D. Brunelle c7149d6bce Fix remap handling by blktrace
This patch provides more information concerning REMAP operations on block
IOs. The additional information provides clearer details at the user level,
and supports post-processing analysis in btt.

o  Adds in partition remaps on the same device.
o  Fixed up the remap information in DM to be in the right order
o  Sent up mapped-from and mapped-to device information

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-08-11 22:34:48 +02:00

1571 lines
32 KiB
C

/*
* Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-bio-list.h"
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/moduleparam.h>
#include <linux/blkpg.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/hdreg.h>
#include <linux/blktrace_api.h>
#include <linux/smp_lock.h>
#define DM_MSG_PREFIX "core"
static const char *_name = DM_NAME;
static unsigned int major = 0;
static unsigned int _major = 0;
static DEFINE_SPINLOCK(_minor_lock);
/*
* One of these is allocated per bio.
*/
struct dm_io {
struct mapped_device *md;
int error;
struct bio *bio;
atomic_t io_count;
unsigned long start_time;
};
/*
* One of these is allocated per target within a bio. Hopefully
* this will be simplified out one day.
*/
struct dm_target_io {
struct dm_io *io;
struct dm_target *ti;
union map_info info;
};
union map_info *dm_get_mapinfo(struct bio *bio)
{
if (bio && bio->bi_private)
return &((struct dm_target_io *)bio->bi_private)->info;
return NULL;
}
#define MINOR_ALLOCED ((void *)-1)
/*
* Bits for the md->flags field.
*/
#define DMF_BLOCK_IO 0
#define DMF_SUSPENDED 1
#define DMF_FROZEN 2
#define DMF_FREEING 3
#define DMF_DELETING 4
#define DMF_NOFLUSH_SUSPENDING 5
struct mapped_device {
struct rw_semaphore io_lock;
struct semaphore suspend_lock;
spinlock_t pushback_lock;
rwlock_t map_lock;
atomic_t holders;
atomic_t open_count;
unsigned long flags;
struct request_queue *queue;
struct gendisk *disk;
char name[16];
void *interface_ptr;
/*
* A list of ios that arrived while we were suspended.
*/
atomic_t pending;
wait_queue_head_t wait;
struct bio_list deferred;
struct bio_list pushback;
/*
* The current mapping.
*/
struct dm_table *map;
/*
* io objects are allocated from here.
*/
mempool_t *io_pool;
mempool_t *tio_pool;
struct bio_set *bs;
/*
* Event handling.
*/
atomic_t event_nr;
wait_queue_head_t eventq;
/*
* freeze/thaw support require holding onto a super block
*/
struct super_block *frozen_sb;
struct block_device *suspended_bdev;
/* forced geometry settings */
struct hd_geometry geometry;
};
#define MIN_IOS 256
static struct kmem_cache *_io_cache;
static struct kmem_cache *_tio_cache;
static int __init local_init(void)
{
int r;
/* allocate a slab for the dm_ios */
_io_cache = KMEM_CACHE(dm_io, 0);
if (!_io_cache)
return -ENOMEM;
/* allocate a slab for the target ios */
_tio_cache = KMEM_CACHE(dm_target_io, 0);
if (!_tio_cache) {
kmem_cache_destroy(_io_cache);
return -ENOMEM;
}
_major = major;
r = register_blkdev(_major, _name);
if (r < 0) {
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
return r;
}
if (!_major)
_major = r;
return 0;
}
static void local_exit(void)
{
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
unregister_blkdev(_major, _name);
_major = 0;
DMINFO("cleaned up");
}
int (*_inits[])(void) __initdata = {
local_init,
dm_target_init,
dm_linear_init,
dm_stripe_init,
dm_interface_init,
};
void (*_exits[])(void) = {
local_exit,
dm_target_exit,
dm_linear_exit,
dm_stripe_exit,
dm_interface_exit,
};
static int __init dm_init(void)
{
const int count = ARRAY_SIZE(_inits);
int r, i;
for (i = 0; i < count; i++) {
r = _inits[i]();
if (r)
goto bad;
}
return 0;
bad:
while (i--)
_exits[i]();
return r;
}
static void __exit dm_exit(void)
{
int i = ARRAY_SIZE(_exits);
while (i--)
_exits[i]();
}
/*
* Block device functions
*/
static int dm_blk_open(struct inode *inode, struct file *file)
{
struct mapped_device *md;
spin_lock(&_minor_lock);
md = inode->i_bdev->bd_disk->private_data;
if (!md)
goto out;
if (test_bit(DMF_FREEING, &md->flags) ||
test_bit(DMF_DELETING, &md->flags)) {
md = NULL;
goto out;
}
dm_get(md);
atomic_inc(&md->open_count);
out:
spin_unlock(&_minor_lock);
return md ? 0 : -ENXIO;
}
static int dm_blk_close(struct inode *inode, struct file *file)
{
struct mapped_device *md;
md = inode->i_bdev->bd_disk->private_data;
atomic_dec(&md->open_count);
dm_put(md);
return 0;
}
int dm_open_count(struct mapped_device *md)
{
return atomic_read(&md->open_count);
}
/*
* Guarantees nothing is using the device before it's deleted.
*/
int dm_lock_for_deletion(struct mapped_device *md)
{
int r = 0;
spin_lock(&_minor_lock);
if (dm_open_count(md))
r = -EBUSY;
else
set_bit(DMF_DELETING, &md->flags);
spin_unlock(&_minor_lock);
return r;
}
static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct mapped_device *md = bdev->bd_disk->private_data;
return dm_get_geometry(md, geo);
}
static int dm_blk_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct mapped_device *md;
struct dm_table *map;
struct dm_target *tgt;
int r = -ENOTTY;
/* We don't really need this lock, but we do need 'inode'. */
unlock_kernel();
md = inode->i_bdev->bd_disk->private_data;
map = dm_get_table(md);
if (!map || !dm_table_get_size(map))
goto out;
/* We only support devices that have a single target */
if (dm_table_get_num_targets(map) != 1)
goto out;
tgt = dm_table_get_target(map, 0);
if (dm_suspended(md)) {
r = -EAGAIN;
goto out;
}
if (tgt->type->ioctl)
r = tgt->type->ioctl(tgt, inode, file, cmd, arg);
out:
dm_table_put(map);
lock_kernel();
return r;
}
static struct dm_io *alloc_io(struct mapped_device *md)
{
return mempool_alloc(md->io_pool, GFP_NOIO);
}
static void free_io(struct mapped_device *md, struct dm_io *io)
{
mempool_free(io, md->io_pool);
}
static struct dm_target_io *alloc_tio(struct mapped_device *md)
{
return mempool_alloc(md->tio_pool, GFP_NOIO);
}
static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
{
mempool_free(tio, md->tio_pool);
}
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
io->start_time = jiffies;
preempt_disable();
disk_round_stats(dm_disk(md));
preempt_enable();
dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
}
static int end_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
struct bio *bio = io->bio;
unsigned long duration = jiffies - io->start_time;
int pending;
int rw = bio_data_dir(bio);
preempt_disable();
disk_round_stats(dm_disk(md));
preempt_enable();
dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);
disk_stat_add(dm_disk(md), ticks[rw], duration);
return !pending;
}
/*
* Add the bio to the list of deferred io.
*/
static int queue_io(struct mapped_device *md, struct bio *bio)
{
down_write(&md->io_lock);
if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
up_write(&md->io_lock);
return 1;
}
bio_list_add(&md->deferred, bio);
up_write(&md->io_lock);
return 0; /* deferred successfully */
}
/*
* Everyone (including functions in this file), should use this
* function to access the md->map field, and make sure they call
* dm_table_put() when finished.
*/
struct dm_table *dm_get_table(struct mapped_device *md)
{
struct dm_table *t;
read_lock(&md->map_lock);
t = md->map;
if (t)
dm_table_get(t);
read_unlock(&md->map_lock);
return t;
}
/*
* Get the geometry associated with a dm device
*/
int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
{
*geo = md->geometry;
return 0;
}
/*
* Set the geometry of a device.
*/
int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
{
sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
if (geo->start > sz) {
DMWARN("Start sector is beyond the geometry limits.");
return -EINVAL;
}
md->geometry = *geo;
return 0;
}
/*-----------------------------------------------------------------
* CRUD START:
* A more elegant soln is in the works that uses the queue
* merge fn, unfortunately there are a couple of changes to
* the block layer that I want to make for this. So in the
* interests of getting something for people to use I give
* you this clearly demarcated crap.
*---------------------------------------------------------------*/
static int __noflush_suspending(struct mapped_device *md)
{
return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
}
/*
* Decrements the number of outstanding ios that a bio has been
* cloned into, completing the original io if necc.
*/
static void dec_pending(struct dm_io *io, int error)
{
unsigned long flags;
/* Push-back supersedes any I/O errors */
if (error && !(io->error > 0 && __noflush_suspending(io->md)))
io->error = error;
if (atomic_dec_and_test(&io->io_count)) {
if (io->error == DM_ENDIO_REQUEUE) {
/*
* Target requested pushing back the I/O.
* This must be handled before the sleeper on
* suspend queue merges the pushback list.
*/
spin_lock_irqsave(&io->md->pushback_lock, flags);
if (__noflush_suspending(io->md))
bio_list_add(&io->md->pushback, io->bio);
else
/* noflush suspend was interrupted. */
io->error = -EIO;
spin_unlock_irqrestore(&io->md->pushback_lock, flags);
}
if (end_io_acct(io))
/* nudge anyone waiting on suspend queue */
wake_up(&io->md->wait);
if (io->error != DM_ENDIO_REQUEUE) {
blk_add_trace_bio(io->md->queue, io->bio,
BLK_TA_COMPLETE);
bio_endio(io->bio, io->bio->bi_size, io->error);
}
free_io(io->md, io);
}
}
static int clone_endio(struct bio *bio, unsigned int done, int error)
{
int r = 0;
struct dm_target_io *tio = bio->bi_private;
struct mapped_device *md = tio->io->md;
dm_endio_fn endio = tio->ti->type->end_io;
if (bio->bi_size)
return 1;
if (!bio_flagged(bio, BIO_UPTODATE) && !error)
error = -EIO;
if (endio) {
r = endio(tio->ti, bio, error, &tio->info);
if (r < 0 || r == DM_ENDIO_REQUEUE)
/*
* error and requeue request are handled
* in dec_pending().
*/
error = r;
else if (r == DM_ENDIO_INCOMPLETE)
/* The target will handle the io */
return 1;
else if (r) {
DMWARN("unimplemented target endio return value: %d", r);
BUG();
}
}
dec_pending(tio->io, error);
/*
* Store md for cleanup instead of tio which is about to get freed.
*/
bio->bi_private = md->bs;
bio_put(bio);
free_tio(md, tio);
return r;
}
static sector_t max_io_len(struct mapped_device *md,
sector_t sector, struct dm_target *ti)
{
sector_t offset = sector - ti->begin;
sector_t len = ti->len - offset;
/*
* Does the target need to split even further ?
*/
if (ti->split_io) {
sector_t boundary;
boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
- offset;
if (len > boundary)
len = boundary;
}
return len;
}
static void __map_bio(struct dm_target *ti, struct bio *clone,
struct dm_target_io *tio)
{
int r;
sector_t sector;
struct mapped_device *md;
/*
* Sanity checks.
*/
BUG_ON(!clone->bi_size);
clone->bi_end_io = clone_endio;
clone->bi_private = tio;
/*
* Map the clone. If r == 0 we don't need to do
* anything, the target has assumed ownership of
* this io.
*/
atomic_inc(&tio->io->io_count);
sector = clone->bi_sector;
r = ti->type->map(ti, clone, &tio->info);
if (r == DM_MAPIO_REMAPPED) {
/* the bio has been remapped so dispatch it */
blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
tio->io->bio->bi_bdev->bd_dev,
clone->bi_sector, sector);
generic_make_request(clone);
} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
/* error the io and bail out, or requeue it if needed */
md = tio->io->md;
dec_pending(tio->io, r);
/*
* Store bio_set for cleanup.
*/
clone->bi_private = md->bs;
bio_put(clone);
free_tio(md, tio);
} else if (r) {
DMWARN("unimplemented target map return value: %d", r);
BUG();
}
}
struct clone_info {
struct mapped_device *md;
struct dm_table *map;
struct bio *bio;
struct dm_io *io;
sector_t sector;
sector_t sector_count;
unsigned short idx;
};
static void dm_bio_destructor(struct bio *bio)
{
struct bio_set *bs = bio->bi_private;
bio_free(bio, bs);
}
/*
* Creates a little bio that is just does part of a bvec.
*/
static struct bio *split_bvec(struct bio *bio, sector_t sector,
unsigned short idx, unsigned int offset,
unsigned int len, struct bio_set *bs)
{
struct bio *clone;
struct bio_vec *bv = bio->bi_io_vec + idx;
clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
clone->bi_destructor = dm_bio_destructor;
*clone->bi_io_vec = *bv;
clone->bi_sector = sector;
clone->bi_bdev = bio->bi_bdev;
clone->bi_rw = bio->bi_rw;
clone->bi_vcnt = 1;
clone->bi_size = to_bytes(len);
clone->bi_io_vec->bv_offset = offset;
clone->bi_io_vec->bv_len = clone->bi_size;
return clone;
}
/*
* Creates a bio that consists of range of complete bvecs.
*/
static struct bio *clone_bio(struct bio *bio, sector_t sector,
unsigned short idx, unsigned short bv_count,
unsigned int len, struct bio_set *bs)
{
struct bio *clone;
clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
__bio_clone(clone, bio);
clone->bi_destructor = dm_bio_destructor;
clone->bi_sector = sector;
clone->bi_idx = idx;
clone->bi_vcnt = idx + bv_count;
clone->bi_size = to_bytes(len);
clone->bi_flags &= ~(1 << BIO_SEG_VALID);
return clone;
}
static void __clone_and_map(struct clone_info *ci)
{
struct bio *clone, *bio = ci->bio;
struct dm_target *ti = dm_table_find_target(ci->map, ci->sector);
sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti);
struct dm_target_io *tio;
/*
* Allocate a target io object.
*/
tio = alloc_tio(ci->md);
tio->io = ci->io;
tio->ti = ti;
memset(&tio->info, 0, sizeof(tio->info));
if (ci->sector_count <= max) {
/*
* Optimise for the simple case where we can do all of
* the remaining io with a single clone.
*/
clone = clone_bio(bio, ci->sector, ci->idx,
bio->bi_vcnt - ci->idx, ci->sector_count,
ci->md->bs);
__map_bio(ti, clone, tio);
ci->sector_count = 0;
} else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
/*
* There are some bvecs that don't span targets.
* Do as many of these as possible.
*/
int i;
sector_t remaining = max;
sector_t bv_len;
for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
bv_len = to_sector(bio->bi_io_vec[i].bv_len);
if (bv_len > remaining)
break;
remaining -= bv_len;
len += bv_len;
}
clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
ci->md->bs);
__map_bio(ti, clone, tio);
ci->sector += len;
ci->sector_count -= len;
ci->idx = i;
} else {
/*
* Handle a bvec that must be split between two or more targets.
*/
struct bio_vec *bv = bio->bi_io_vec + ci->idx;
sector_t remaining = to_sector(bv->bv_len);
unsigned int offset = 0;
do {
if (offset) {
ti = dm_table_find_target(ci->map, ci->sector);
max = max_io_len(ci->md, ci->sector, ti);
tio = alloc_tio(ci->md);
tio->io = ci->io;
tio->ti = ti;
memset(&tio->info, 0, sizeof(tio->info));
}
len = min(remaining, max);
clone = split_bvec(bio, ci->sector, ci->idx,
bv->bv_offset + offset, len,
ci->md->bs);
__map_bio(ti, clone, tio);
ci->sector += len;
ci->sector_count -= len;
offset += to_bytes(len);
} while (remaining -= len);
ci->idx++;
}
}
/*
* Split the bio into several clones.
*/
static void __split_bio(struct mapped_device *md, struct bio *bio)
{
struct clone_info ci;
ci.map = dm_get_table(md);
if (!ci.map) {
bio_io_error(bio, bio->bi_size);
return;
}
ci.md = md;
ci.bio = bio;
ci.io = alloc_io(md);
ci.io->error = 0;
atomic_set(&ci.io->io_count, 1);
ci.io->bio = bio;
ci.io->md = md;
ci.sector = bio->bi_sector;
ci.sector_count = bio_sectors(bio);
ci.idx = bio->bi_idx;
start_io_acct(ci.io);
while (ci.sector_count)
__clone_and_map(&ci);
/* drop the extra reference count */
dec_pending(ci.io, 0);
dm_table_put(ci.map);
}
/*-----------------------------------------------------------------
* CRUD END
*---------------------------------------------------------------*/
/*
* The request function that just remaps the bio built up by
* dm_merge_bvec.
*/
static int dm_request(struct request_queue *q, struct bio *bio)
{
int r;
int rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata;
/*
* There is no use in forwarding any barrier request since we can't
* guarantee it is (or can be) handled by the targets correctly.
*/
if (unlikely(bio_barrier(bio))) {
bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
return 0;
}
down_read(&md->io_lock);
disk_stat_inc(dm_disk(md), ios[rw]);
disk_stat_add(dm_disk(md), sectors[rw], bio_sectors(bio));
/*
* If we're suspended we have to queue
* this io for later.
*/
while (test_bit(DMF_BLOCK_IO, &md->flags)) {
up_read(&md->io_lock);
if (bio_rw(bio) == READA) {
bio_io_error(bio, bio->bi_size);
return 0;
}
r = queue_io(md, bio);
if (r < 0) {
bio_io_error(bio, bio->bi_size);
return 0;
} else if (r == 0)
return 0; /* deferred successfully */
/*
* We're in a while loop, because someone could suspend
* before we get to the following read lock.
*/
down_read(&md->io_lock);
}
__split_bio(md, bio);
up_read(&md->io_lock);
return 0;
}
static int dm_flush_all(struct request_queue *q, struct gendisk *disk,
sector_t *error_sector)
{
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_table(md);
int ret = -ENXIO;
if (map) {
ret = dm_table_flush_all(map);
dm_table_put(map);
}
return ret;
}
static void dm_unplug_all(struct request_queue *q)
{
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_table(md);
if (map) {
dm_table_unplug_all(map);
dm_table_put(map);
}
}
static int dm_any_congested(void *congested_data, int bdi_bits)
{
int r;
struct mapped_device *md = (struct mapped_device *) congested_data;
struct dm_table *map = dm_get_table(md);
if (!map || test_bit(DMF_BLOCK_IO, &md->flags))
r = bdi_bits;
else
r = dm_table_any_congested(map, bdi_bits);
dm_table_put(map);
return r;
}
/*-----------------------------------------------------------------
* An IDR is used to keep track of allocated minor numbers.
*---------------------------------------------------------------*/
static DEFINE_IDR(_minor_idr);
static void free_minor(int minor)
{
spin_lock(&_minor_lock);
idr_remove(&_minor_idr, minor);
spin_unlock(&_minor_lock);
}
/*
* See if the device with a specific minor # is free.
*/
static int specific_minor(struct mapped_device *md, int minor)
{
int r, m;
if (minor >= (1 << MINORBITS))
return -EINVAL;
r = idr_pre_get(&_minor_idr, GFP_KERNEL);
if (!r)
return -ENOMEM;
spin_lock(&_minor_lock);
if (idr_find(&_minor_idr, minor)) {
r = -EBUSY;
goto out;
}
r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
if (r)
goto out;
if (m != minor) {
idr_remove(&_minor_idr, m);
r = -EBUSY;
goto out;
}
out:
spin_unlock(&_minor_lock);
return r;
}
static int next_free_minor(struct mapped_device *md, int *minor)
{
int r, m;
r = idr_pre_get(&_minor_idr, GFP_KERNEL);
if (!r)
return -ENOMEM;
spin_lock(&_minor_lock);
r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
if (r) {
goto out;
}
if (m >= (1 << MINORBITS)) {
idr_remove(&_minor_idr, m);
r = -ENOSPC;
goto out;
}
*minor = m;
out:
spin_unlock(&_minor_lock);
return r;
}
static struct block_device_operations dm_blk_dops;
/*
* Allocate and initialise a blank device with a given minor.
*/
static struct mapped_device *alloc_dev(int minor)
{
int r;
struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
void *old_md;
if (!md) {
DMWARN("unable to allocate device, out of memory.");
return NULL;
}
if (!try_module_get(THIS_MODULE))
goto bad0;
/* get a minor number for the dev */
if (minor == DM_ANY_MINOR)
r = next_free_minor(md, &minor);
else
r = specific_minor(md, minor);
if (r < 0)
goto bad1;
memset(md, 0, sizeof(*md));
init_rwsem(&md->io_lock);
init_MUTEX(&md->suspend_lock);
spin_lock_init(&md->pushback_lock);
rwlock_init(&md->map_lock);
atomic_set(&md->holders, 1);
atomic_set(&md->open_count, 0);
atomic_set(&md->event_nr, 0);
md->queue = blk_alloc_queue(GFP_KERNEL);
if (!md->queue)
goto bad1_free_minor;
md->queue->queuedata = md;
md->queue->backing_dev_info.congested_fn = dm_any_congested;
md->queue->backing_dev_info.congested_data = md;
blk_queue_make_request(md->queue, dm_request);
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
md->queue->unplug_fn = dm_unplug_all;
md->queue->issue_flush_fn = dm_flush_all;
md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
if (!md->io_pool)
goto bad2;
md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
if (!md->tio_pool)
goto bad3;
md->bs = bioset_create(16, 16);
if (!md->bs)
goto bad_no_bioset;
md->disk = alloc_disk(1);
if (!md->disk)
goto bad4;
atomic_set(&md->pending, 0);
init_waitqueue_head(&md->wait);
init_waitqueue_head(&md->eventq);
md->disk->major = _major;
md->disk->first_minor = minor;
md->disk->fops = &dm_blk_dops;
md->disk->queue = md->queue;
md->disk->private_data = md;
sprintf(md->disk->disk_name, "dm-%d", minor);
add_disk(md->disk);
format_dev_t(md->name, MKDEV(_major, minor));
/* Populate the mapping, nobody knows we exist yet */
spin_lock(&_minor_lock);
old_md = idr_replace(&_minor_idr, md, minor);
spin_unlock(&_minor_lock);
BUG_ON(old_md != MINOR_ALLOCED);
return md;
bad4:
bioset_free(md->bs);
bad_no_bioset:
mempool_destroy(md->tio_pool);
bad3:
mempool_destroy(md->io_pool);
bad2:
blk_cleanup_queue(md->queue);
bad1_free_minor:
free_minor(minor);
bad1:
module_put(THIS_MODULE);
bad0:
kfree(md);
return NULL;
}
static void free_dev(struct mapped_device *md)
{
int minor = md->disk->first_minor;
if (md->suspended_bdev) {
thaw_bdev(md->suspended_bdev, NULL);
bdput(md->suspended_bdev);
}
mempool_destroy(md->tio_pool);
mempool_destroy(md->io_pool);
bioset_free(md->bs);
del_gendisk(md->disk);
free_minor(minor);
spin_lock(&_minor_lock);
md->disk->private_data = NULL;
spin_unlock(&_minor_lock);
put_disk(md->disk);
blk_cleanup_queue(md->queue);
module_put(THIS_MODULE);
kfree(md);
}
/*
* Bind a table to the device.
*/
static void event_callback(void *context)
{
struct mapped_device *md = (struct mapped_device *) context;
atomic_inc(&md->event_nr);
wake_up(&md->eventq);
}
static void __set_size(struct mapped_device *md, sector_t size)
{
set_capacity(md->disk, size);
mutex_lock(&md->suspended_bdev->bd_inode->i_mutex);
i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex);
}
static int __bind(struct mapped_device *md, struct dm_table *t)
{
struct request_queue *q = md->queue;
sector_t size;
size = dm_table_get_size(t);
/*
* Wipe any geometry if the size of the table changed.
*/
if (size != get_capacity(md->disk))
memset(&md->geometry, 0, sizeof(md->geometry));
if (md->suspended_bdev)
__set_size(md, size);
if (size == 0)
return 0;
dm_table_get(t);
dm_table_event_callback(t, event_callback, md);
write_lock(&md->map_lock);
md->map = t;
dm_table_set_restrictions(t, q);
write_unlock(&md->map_lock);
return 0;
}
static void __unbind(struct mapped_device *md)
{
struct dm_table *map = md->map;
if (!map)
return;
dm_table_event_callback(map, NULL, NULL);
write_lock(&md->map_lock);
md->map = NULL;
write_unlock(&md->map_lock);
dm_table_put(map);
}
/*
* Constructor for a new device.
*/
int dm_create(int minor, struct mapped_device **result)
{
struct mapped_device *md;
md = alloc_dev(minor);
if (!md)
return -ENXIO;
*result = md;
return 0;
}
static struct mapped_device *dm_find_md(dev_t dev)
{
struct mapped_device *md;
unsigned minor = MINOR(dev);
if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
return NULL;
spin_lock(&_minor_lock);
md = idr_find(&_minor_idr, minor);
if (md && (md == MINOR_ALLOCED ||
(dm_disk(md)->first_minor != minor) ||
test_bit(DMF_FREEING, &md->flags))) {
md = NULL;
goto out;
}
out:
spin_unlock(&_minor_lock);
return md;
}
struct mapped_device *dm_get_md(dev_t dev)
{
struct mapped_device *md = dm_find_md(dev);
if (md)
dm_get(md);
return md;
}
void *dm_get_mdptr(struct mapped_device *md)
{
return md->interface_ptr;
}
void dm_set_mdptr(struct mapped_device *md, void *ptr)
{
md->interface_ptr = ptr;
}
void dm_get(struct mapped_device *md)
{
atomic_inc(&md->holders);
}
const char *dm_device_name(struct mapped_device *md)
{
return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);
void dm_put(struct mapped_device *md)
{
struct dm_table *map;
BUG_ON(test_bit(DMF_FREEING, &md->flags));
if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
map = dm_get_table(md);
idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);
if (!dm_suspended(md)) {
dm_table_presuspend_targets(map);
dm_table_postsuspend_targets(map);
}
__unbind(md);
dm_table_put(map);
free_dev(md);
}
}
EXPORT_SYMBOL_GPL(dm_put);
/*
* Process the deferred bios
*/
static void __flush_deferred_io(struct mapped_device *md, struct bio *c)
{
struct bio *n;
while (c) {
n = c->bi_next;
c->bi_next = NULL;
__split_bio(md, c);
c = n;
}
}
/*
* Swap in a new table (destroying old one).
*/
int dm_swap_table(struct mapped_device *md, struct dm_table *table)
{
int r = -EINVAL;
down(&md->suspend_lock);
/* device must be suspended */
if (!dm_suspended(md))
goto out;
/* without bdev, the device size cannot be changed */
if (!md->suspended_bdev)
if (get_capacity(md->disk) != dm_table_get_size(table))
goto out;
__unbind(md);
r = __bind(md, table);
out:
up(&md->suspend_lock);
return r;
}
/*
* Functions to lock and unlock any filesystem running on the
* device.
*/
static int lock_fs(struct mapped_device *md)
{
int r;
WARN_ON(md->frozen_sb);
md->frozen_sb = freeze_bdev(md->suspended_bdev);
if (IS_ERR(md->frozen_sb)) {
r = PTR_ERR(md->frozen_sb);
md->frozen_sb = NULL;
return r;
}
set_bit(DMF_FROZEN, &md->flags);
/* don't bdput right now, we don't want the bdev
* to go away while it is locked.
*/
return 0;
}
static void unlock_fs(struct mapped_device *md)
{
if (!test_bit(DMF_FROZEN, &md->flags))
return;
thaw_bdev(md->suspended_bdev, md->frozen_sb);
md->frozen_sb = NULL;
clear_bit(DMF_FROZEN, &md->flags);
}
/*
* We need to be able to change a mapping table under a mounted
* filesystem. For example we might want to move some data in
* the background. Before the table can be swapped with
* dm_bind_table, dm_suspend must be called to flush any in
* flight bios and ensure that any further io gets deferred.
*/
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
{
struct dm_table *map = NULL;
unsigned long flags;
DECLARE_WAITQUEUE(wait, current);
struct bio *def;
int r = -EINVAL;
int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
down(&md->suspend_lock);
if (dm_suspended(md))
goto out_unlock;
map = dm_get_table(md);
/*
* DMF_NOFLUSH_SUSPENDING must be set before presuspend.
* This flag is cleared before dm_suspend returns.
*/
if (noflush)
set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
/* This does not get reverted if there's an error later. */
dm_table_presuspend_targets(map);
/* bdget() can stall if the pending I/Os are not flushed */
if (!noflush) {
md->suspended_bdev = bdget_disk(md->disk, 0);
if (!md->suspended_bdev) {
DMWARN("bdget failed in dm_suspend");
r = -ENOMEM;
goto flush_and_out;
}
}
/*
* Flush I/O to the device.
* noflush supersedes do_lockfs, because lock_fs() needs to flush I/Os.
*/
if (do_lockfs && !noflush) {
r = lock_fs(md);
if (r)
goto out;
}
/*
* First we set the BLOCK_IO flag so no more ios will be mapped.
*/
down_write(&md->io_lock);
set_bit(DMF_BLOCK_IO, &md->flags);
add_wait_queue(&md->wait, &wait);
up_write(&md->io_lock);
/* unplug */
if (map)
dm_table_unplug_all(map);
/*
* Then we wait for the already mapped ios to
* complete.
*/
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
if (!atomic_read(&md->pending) || signal_pending(current))
break;
io_schedule();
}
set_current_state(TASK_RUNNING);
down_write(&md->io_lock);
remove_wait_queue(&md->wait, &wait);
if (noflush) {
spin_lock_irqsave(&md->pushback_lock, flags);
clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
bio_list_merge_head(&md->deferred, &md->pushback);
bio_list_init(&md->pushback);
spin_unlock_irqrestore(&md->pushback_lock, flags);
}
/* were we interrupted ? */
r = -EINTR;
if (atomic_read(&md->pending)) {
clear_bit(DMF_BLOCK_IO, &md->flags);
def = bio_list_get(&md->deferred);
__flush_deferred_io(md, def);
up_write(&md->io_lock);
unlock_fs(md);
goto out; /* pushback list is already flushed, so skip flush */
}
up_write(&md->io_lock);
dm_table_postsuspend_targets(map);
set_bit(DMF_SUSPENDED, &md->flags);
r = 0;
flush_and_out:
if (r && noflush) {
/*
* Because there may be already I/Os in the pushback list,
* flush them before return.
*/
down_write(&md->io_lock);
spin_lock_irqsave(&md->pushback_lock, flags);
clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
bio_list_merge_head(&md->deferred, &md->pushback);
bio_list_init(&md->pushback);
spin_unlock_irqrestore(&md->pushback_lock, flags);
def = bio_list_get(&md->deferred);
__flush_deferred_io(md, def);
up_write(&md->io_lock);
}
out:
if (r && md->suspended_bdev) {
bdput(md->suspended_bdev);
md->suspended_bdev = NULL;
}
dm_table_put(map);
out_unlock:
up(&md->suspend_lock);
return r;
}
int dm_resume(struct mapped_device *md)
{
int r = -EINVAL;
struct bio *def;
struct dm_table *map = NULL;
down(&md->suspend_lock);
if (!dm_suspended(md))
goto out;
map = dm_get_table(md);
if (!map || !dm_table_get_size(map))
goto out;
r = dm_table_resume_targets(map);
if (r)
goto out;
down_write(&md->io_lock);
clear_bit(DMF_BLOCK_IO, &md->flags);
def = bio_list_get(&md->deferred);
__flush_deferred_io(md, def);
up_write(&md->io_lock);
unlock_fs(md);
if (md->suspended_bdev) {
bdput(md->suspended_bdev);
md->suspended_bdev = NULL;
}
clear_bit(DMF_SUSPENDED, &md->flags);
dm_table_unplug_all(map);
kobject_uevent(&md->disk->kobj, KOBJ_CHANGE);
r = 0;
out:
dm_table_put(map);
up(&md->suspend_lock);
return r;
}
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/
uint32_t dm_get_event_nr(struct mapped_device *md)
{
return atomic_read(&md->event_nr);
}
int dm_wait_event(struct mapped_device *md, int event_nr)
{
return wait_event_interruptible(md->eventq,
(event_nr != atomic_read(&md->event_nr)));
}
/*
* The gendisk is only valid as long as you have a reference
* count on 'md'.
*/
struct gendisk *dm_disk(struct mapped_device *md)
{
return md->disk;
}
int dm_suspended(struct mapped_device *md)
{
return test_bit(DMF_SUSPENDED, &md->flags);
}
int dm_noflush_suspending(struct dm_target *ti)
{
struct mapped_device *md = dm_table_get_md(ti->table);
int r = __noflush_suspending(md);
dm_put(md);
return r;
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);
static struct block_device_operations dm_blk_dops = {
.open = dm_blk_open,
.release = dm_blk_close,
.ioctl = dm_blk_ioctl,
.getgeo = dm_blk_getgeo,
.owner = THIS_MODULE
};
EXPORT_SYMBOL(dm_get_mapinfo);
/*
* module hooks
*/
module_init(dm_init);
module_exit(dm_exit);
module_param(major, uint, 0);
MODULE_PARM_DESC(major, "The major number of the device mapper");
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");