Linux-2.6.33.2/drivers/md/dm.c
/*
* Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-uevent.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 <trace/events/block.h>
#define DM_MSG_PREFIX "core"
/*
* Cookies are numeric values sent with CHANGE and REMOVE
* uevents while resuming, removing or renaming the device.
*/
#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
#define DM_COOKIE_LENGTH 24
static const char *_name = DM_NAME;
static unsigned int major = 0;
static unsigned int _major = 0;
static DEFINE_SPINLOCK(_minor_lock);
/*
* For bio-based dm.
* One of these is allocated per bio.
*/
struct dm_io {
struct mapped_device *md;
int error;
atomic_t io_count;
struct bio *bio;
unsigned long start_time;
spinlock_t endio_lock;
};
/*
* For bio-based dm.
* 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;
};
/*
* For request-based dm.
* One of these is allocated per request.
*/
struct dm_rq_target_io {
struct mapped_device *md;
struct dm_target *ti;
struct request *orig, clone;
int error;
union map_info info;
};
/*
* For request-based dm.
* One of these is allocated per bio.
*/
struct dm_rq_clone_bio_info {
struct bio *orig;
struct dm_rq_target_io *tio;
};
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;
}
union map_info *dm_get_rq_mapinfo(struct request *rq)
{
if (rq && rq->end_io_data)
return &((struct dm_rq_target_io *)rq->end_io_data)->info;
return NULL;
}
EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
#define MINOR_ALLOCED ((void *)-1)
/*
* Bits for the md->flags field.
*/
#define DMF_BLOCK_IO_FOR_SUSPEND 0
#define DMF_SUSPENDED 1
#define DMF_FROZEN 2
#define DMF_FREEING 3
#define DMF_DELETING 4
#define DMF_NOFLUSH_SUSPENDING 5
#define DMF_QUEUE_IO_TO_THREAD 6
/*
* Work processed by per-device workqueue.
*/
struct mapped_device {
struct rw_semaphore io_lock;
struct mutex suspend_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[2];
wait_queue_head_t wait;
struct work_struct work;
struct bio_list deferred;
spinlock_t deferred_lock;
/*
* An error from the barrier request currently being processed.
*/
int barrier_error;
/*
* Protect barrier_error from concurrent endio processing
* in request-based dm.
*/
spinlock_t barrier_error_lock;
/*
* Processing queue (flush/barriers)
*/
struct workqueue_struct *wq;
struct work_struct barrier_work;
/* A pointer to the currently processing pre/post flush request */
struct request *flush_request;
/*
* 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;
atomic_t uevent_seq;
struct list_head uevent_list;
spinlock_t uevent_lock; /* Protect access to uevent_list */
/*
* freeze/thaw support require holding onto a super block
*/
struct super_block *frozen_sb;
struct block_device *bdev;
/* forced geometry settings */
struct hd_geometry geometry;
/* For saving the address of __make_request for request based dm */
make_request_fn *saved_make_request_fn;
/* sysfs handle */
struct kobject kobj;
/* zero-length barrier that will be cloned and submitted to targets */
struct bio barrier_bio;
};
/*
* For mempools pre-allocation at the table loading time.
*/
struct dm_md_mempools {
mempool_t *io_pool;
mempool_t *tio_pool;
struct bio_set *bs;
};
#define MIN_IOS 256
static struct kmem_cache *_io_cache;
static struct kmem_cache *_tio_cache;
static struct kmem_cache *_rq_tio_cache;
static struct kmem_cache *_rq_bio_info_cache;
static int __init local_init(void)
{
int r = -ENOMEM;
/* allocate a slab for the dm_ios */
_io_cache = KMEM_CACHE(dm_io, 0);
if (!_io_cache)
return r;
/* allocate a slab for the target ios */
_tio_cache = KMEM_CACHE(dm_target_io, 0);
if (!_tio_cache)
goto out_free_io_cache;
_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
if (!_rq_tio_cache)
goto out_free_tio_cache;
_rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0);
if (!_rq_bio_info_cache)
goto out_free_rq_tio_cache;
r = dm_uevent_init();
if (r)
goto out_free_rq_bio_info_cache;
_major = major;
r = register_blkdev(_major, _name);
if (r < 0)
goto out_uevent_exit;
if (!_major)
_major = r;
return 0;
out_uevent_exit:
dm_uevent_exit();
out_free_rq_bio_info_cache:
kmem_cache_destroy(_rq_bio_info_cache);
out_free_rq_tio_cache:
kmem_cache_destroy(_rq_tio_cache);
out_free_tio_cache:
kmem_cache_destroy(_tio_cache);
out_free_io_cache:
kmem_cache_destroy(_io_cache);
return r;
}
static void local_exit(void)
{
kmem_cache_destroy(_rq_bio_info_cache);
kmem_cache_destroy(_rq_tio_cache);
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
unregister_blkdev(_major, _name);
dm_uevent_exit();
_major = 0;
DMINFO("cleaned up");
}
static int (*_inits[])(void) __initdata = {
local_init,
dm_target_init,
dm_linear_init,
dm_stripe_init,
dm_io_init,
dm_kcopyd_init,
dm_interface_init,
};
static void (*_exits[])(void) = {
local_exit,
dm_target_exit,
dm_linear_exit,
dm_stripe_exit,
dm_io_exit,
dm_kcopyd_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
*/
int dm_deleting_md(struct mapped_device *md)
{
return test_bit(DMF_DELETING, &md->flags);
}
static int dm_blk_open(struct block_device *bdev, fmode_t mode)
{
struct mapped_device *md;
spin_lock(&_minor_lock);
md = bdev->bd_disk->private_data;
if (!md)
goto out;
if (test_bit(DMF_FREEING, &md->flags) ||
dm_deleting_md(md)) {
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 gendisk *disk, fmode_t mode)
{
struct mapped_device *md = 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 block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct mapped_device *md = bdev->bd_disk->private_data;
struct dm_table *map = dm_get_live_table(md);
struct dm_target *tgt;
int r = -ENOTTY;
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(md)) {
r = -EAGAIN;
goto out;
}
if (tgt->type->ioctl)
r = tgt->type->ioctl(tgt, cmd, arg);
out:
dm_table_put(map);
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 void free_tio(struct mapped_device *md, struct dm_target_io *tio)
{
mempool_free(tio, md->tio_pool);
}
static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
gfp_t gfp_mask)
{
return mempool_alloc(md->tio_pool, gfp_mask);
}
static void free_rq_tio(struct dm_rq_target_io *tio)
{
mempool_free(tio, tio->md->tio_pool);
}
static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)
{
return mempool_alloc(md->io_pool, GFP_ATOMIC);
}
static void free_bio_info(struct dm_rq_clone_bio_info *info)
{
mempool_free(info, info->tio->md->io_pool);
}
static int md_in_flight(struct mapped_device *md)
{
return atomic_read(&md->pending[READ]) +
atomic_read(&md->pending[WRITE]);
}
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
int cpu;
int rw = bio_data_dir(io->bio);
io->start_time = jiffies;
cpu = part_stat_lock();
part_round_stats(cpu, &dm_disk(md)->part0);
part_stat_unlock();
dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]);
}
static void 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, cpu;
int rw = bio_data_dir(bio);
cpu = part_stat_lock();
part_round_stats(cpu, &dm_disk(md)->part0);
part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
part_stat_unlock();
/*
* After this is decremented the bio must not be touched if it is
* a barrier.
*/
dm_disk(md)->part0.in_flight[rw] = pending =
atomic_dec_return(&md->pending[rw]);
pending += atomic_read(&md->pending[rw^0x1]);
/* nudge anyone waiting on suspend queue */
if (!pending)
wake_up(&md->wait);
}
/*
* Add the bio to the list of deferred io.
*/
static void queue_io(struct mapped_device *md, struct bio *bio)
{
down_write(&md->io_lock);
spin_lock_irq(&md->deferred_lock);
bio_list_add(&md->deferred, bio);
spin_unlock_irq(&md->deferred_lock);
if (!test_and_set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags))
queue_work(md->wq, &md->work);
up_write(&md->io_lock);
}
/*
* 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_live_table(struct mapped_device *md)
{
struct dm_table *t;
unsigned long flags;
read_lock_irqsave(&md->map_lock, flags);
t = md->map;
if (t)
dm_table_get(t);
read_unlock_irqrestore(&md->map_lock, flags);
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;
int io_error;
struct bio *bio;
struct mapped_device *md = io->md;
/* Push-back supersedes any I/O errors */
if (unlikely(error)) {
spin_lock_irqsave(&io->endio_lock, flags);
if (!(io->error > 0 && __noflush_suspending(md)))
io->error = error;
spin_unlock_irqrestore(&io->endio_lock, flags);
}
if (atomic_dec_and_test(&io->io_count)) {
if (io->error == DM_ENDIO_REQUEUE) {
/*
* Target requested pushing back the I/O.
*/
spin_lock_irqsave(&md->deferred_lock, flags);
if (__noflush_suspending(md)) {
if (!bio_rw_flagged(io->bio, BIO_RW_BARRIER))
bio_list_add_head(&md->deferred,
io->bio);
} else
/* noflush suspend was interrupted. */
io->error = -EIO;
spin_unlock_irqrestore(&md->deferred_lock, flags);
}
io_error = io->error;
bio = io->bio;
if (bio_rw_flagged(bio, BIO_RW_BARRIER)) {
/*
* There can be just one barrier request so we use
* a per-device variable for error reporting.
* Note that you can't touch the bio after end_io_acct
*/
if (!md->barrier_error && io_error != -EOPNOTSUPP)
md->barrier_error = io_error;
end_io_acct(io);
free_io(md, io);
} else {
end_io_acct(io);
free_io(md, io);
if (io_error != DM_ENDIO_REQUEUE) {
trace_block_bio_complete(md->queue, bio);
bio_endio(bio, io_error);
}
}
}
}
static void clone_endio(struct bio *bio, int error)
{
int r = 0;
struct dm_target_io *tio = bio->bi_private;
struct dm_io *io = tio->io;
struct mapped_device *md = tio->io->md;
dm_endio_fn endio = tio->ti->type->end_io;
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;
else if (r) {
DMWARN("unimplemented target endio return value: %d", r);
BUG();
}
}
/*
* Store md for cleanup instead of tio which is about to get freed.
*/
bio->bi_private = md->bs;
free_tio(md, tio);
bio_put(bio);
dec_pending(io, error);
}
/*
* Partial completion handling for request-based dm
*/
static void end_clone_bio(struct bio *clone, int error)
{
struct dm_rq_clone_bio_info *info = clone->bi_private;
struct dm_rq_target_io *tio = info->tio;
struct bio *bio = info->orig;
unsigned int nr_bytes = info->orig->bi_size;
bio_put(clone);
if (tio->error)
/*
* An error has already been detected on the request.
* Once error occurred, just let clone->end_io() handle
* the remainder.
*/
return;
else if (error) {
/*
* Don't notice the error to the upper layer yet.
* The error handling decision is made by the target driver,
* when the request is completed.
*/
tio->error = error;
return;
}
/*
* I/O for the bio successfully completed.
* Notice the data completion to the upper layer.
*/
/*
* bios are processed from the head of the list.
* So the completing bio should always be rq->bio.
* If it's not, something wrong is happening.
*/
if (tio->orig->bio != bio)
DMERR("bio completion is going in the middle of the request");
/*
* Update the original request.
* Do not use blk_end_request() here, because it may complete
* the original request before the clone, and break the ordering.
*/
blk_update_request(tio->orig, 0, nr_bytes);
}
static void store_barrier_error(struct mapped_device *md, int error)
{
unsigned long flags;
spin_lock_irqsave(&md->barrier_error_lock, flags);
/*
* Basically, the first error is taken, but:
* -EOPNOTSUPP supersedes any I/O error.
* Requeue request supersedes any I/O error but -EOPNOTSUPP.
*/
if (!md->barrier_error || error == -EOPNOTSUPP ||
(md->barrier_error != -EOPNOTSUPP &&
error == DM_ENDIO_REQUEUE))
md->barrier_error = error;
spin_unlock_irqrestore(&md->barrier_error_lock, flags);
}
/*
* Don't touch any member of the md after calling this function because
* the md may be freed in dm_put() at the end of this function.
* Or do dm_get() before calling this function and dm_put() later.
*/
static void rq_completed(struct mapped_device *md, int rw, int run_queue)
{
atomic_dec(&md->pending[rw]);
/* nudge anyone waiting on suspend queue */
if (!md_in_flight(md))
wake_up(&md->wait);
if (run_queue)
blk_run_queue(md->queue);
/*
* dm_put() must be at the end of this function. See the comment above
*/
dm_put(md);
}
static void free_rq_clone(struct request *clone)
{
struct dm_rq_target_io *tio = clone->end_io_data;
blk_rq_unprep_clone(clone);
free_rq_tio(tio);
}
/*
* Complete the clone and the original request.
* Must be called without queue lock.
*/
static void dm_end_request(struct request *clone, int error)
{
int rw = rq_data_dir(clone);
int run_queue = 1;
bool is_barrier = blk_barrier_rq(clone);
struct dm_rq_target_io *tio = clone->end_io_data;
struct mapped_device *md = tio->md;
struct request *rq = tio->orig;
if (blk_pc_request(rq) && !is_barrier) {
rq->errors = clone->errors;
rq->resid_len = clone->resid_len;
if (rq->sense)
/*
* We are using the sense buffer of the original
* request.
* So setting the length of the sense data is enough.
*/
rq->sense_len = clone->sense_len;
}
free_rq_clone(clone);
if (unlikely(is_barrier)) {
if (unlikely(error))
store_barrier_error(md, error);
run_queue = 0;
} else
blk_end_request_all(rq, error);
rq_completed(md, rw, run_queue);
}
static void dm_unprep_request(struct request *rq)
{
struct request *clone = rq->special;
rq->special = NULL;
rq->cmd_flags &= ~REQ_DONTPREP;
free_rq_clone(clone);
}
/*
* Requeue the original request of a clone.
*/
void dm_requeue_unmapped_request(struct request *clone)
{
int rw = rq_data_dir(clone);
struct dm_rq_target_io *tio = clone->end_io_data;
struct mapped_device *md = tio->md;
struct request *rq = tio->orig;
struct request_queue *q = rq->q;
unsigned long flags;
if (unlikely(blk_barrier_rq(clone))) {
/*
* Barrier clones share an original request.
* Leave it to dm_end_request(), which handles this special
* case.
*/
dm_end_request(clone, DM_ENDIO_REQUEUE);
return;
}
dm_unprep_request(rq);
spin_lock_irqsave(q->queue_lock, flags);
if (elv_queue_empty(q))
blk_plug_device(q);
blk_requeue_request(q, rq);
spin_unlock_irqrestore(q->queue_lock, flags);
rq_completed(md, rw, 0);
}
EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
static void __stop_queue(struct request_queue *q)
{
blk_stop_queue(q);
}
static void stop_queue(struct request_queue *q)
{
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
__stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
static void __start_queue(struct request_queue *q)
{
if (blk_queue_stopped(q))
blk_start_queue(q);
}
static void start_queue(struct request_queue *q)
{
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
__start_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
static void dm_done(struct request *clone, int error, bool mapped)
{
int r = error;
struct dm_rq_target_io *tio = clone->end_io_data;
dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;
if (mapped && rq_end_io)
r = rq_end_io(tio->ti, clone, error, &tio->info);
if (r <= 0)
/* The target wants to complete the I/O */
dm_end_request(clone, r);
else if (r == DM_ENDIO_INCOMPLETE)
/* The target will handle the I/O */
return;
else if (r == DM_ENDIO_REQUEUE)
/* The target wants to requeue the I/O */
dm_requeue_unmapped_request(clone);
else {
DMWARN("unimplemented target endio return value: %d", r);
BUG();
}
}
/*
* Request completion handler for request-based dm
*/
static void dm_softirq_done(struct request *rq)
{
bool mapped = true;
struct request *clone = rq->completion_data;
struct dm_rq_target_io *tio = clone->end_io_data;
if (rq->cmd_flags & REQ_FAILED)
mapped = false;
dm_done(clone, tio->error, mapped);
}
/*
* Complete the clone and the original request with the error status
* through softirq context.
*/
static void dm_complete_request(struct request *clone, int error)
{
struct dm_rq_target_io *tio = clone->end_io_data;
struct request *rq = tio->orig;
if (unlikely(blk_barrier_rq(clone))) {
/*
* Barrier clones share an original request. So can't use
* softirq_done with the original.
* Pass the clone to dm_done() directly in this special case.
* It is safe (even if clone->q->queue_lock is held here)
* because there is no I/O dispatching during the completion
* of barrier clone.
*/
dm_done(clone, error, true);
return;
}
tio->error = error;
rq->completion_data = clone;
blk_complete_request(rq);
}
/*
* Complete the not-mapped clone and the original request with the error status
* through softirq context.
* Target's rq_end_io() function isn't called.
* This may be used when the target's map_rq() function fails.
*/
void dm_kill_unmapped_request(struct request *clone, int error)
{
struct dm_rq_target_io *tio = clone->end_io_data;
struct request *rq = tio->orig;
if (unlikely(blk_barrier_rq(clone))) {
/*
* Barrier clones share an original request.
* Leave it to dm_end_request(), which handles this special
* case.
*/
BUG_ON(error > 0);
dm_end_request(clone, error);
return;
}
rq->cmd_flags |= REQ_FAILED;
dm_complete_request(clone, error);
}
EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
/*
* Called with the queue lock held
*/
static void end_clone_request(struct request *clone, int error)
{
/*
* For just cleaning up the information of the queue in which
* the clone was dispatched.
* The clone is *NOT* freed actually here because it is alloced from
* dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
*/
__blk_put_request(clone->q, clone);
/*
* Actual request completion is done in a softirq context which doesn't
* hold the queue lock. Otherwise, deadlock could occur because:
* - another request may be submitted by the upper level driver
* of the stacking during the completion
* - the submission which requires queue lock may be done
* against this queue
*/
dm_complete_request(clone, error);
}
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;
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 */
trace_block_remap(bdev_get_queue(clone->bi_bdev), clone,
tio->io->bio->bi_bdev->bd_dev, 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 & ~(1 << BIO_RW_BARRIER);
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;
clone->bi_flags |= 1 << BIO_CLONED;
if (bio_integrity(bio)) {
bio_integrity_clone(clone, bio, GFP_NOIO, bs);
bio_integrity_trim(clone,
bio_sector_offset(bio, idx, offset), len);
}
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_rw &= ~(1 << BIO_RW_BARRIER);
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);
if (bio_integrity(bio)) {
bio_integrity_clone(clone, bio, GFP_NOIO, bs);
if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
bio_integrity_trim(clone,
bio_sector_offset(bio, idx, 0), len);
}
return clone;
}
static struct dm_target_io *alloc_tio(struct clone_info *ci,
struct dm_target *ti)
{
struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO);
tio->io = ci->io;
tio->ti = ti;
memset(&tio->info, 0, sizeof(tio->info));
return tio;
}
static void __flush_target(struct clone_info *ci, struct dm_target *ti,
unsigned flush_nr)
{
struct dm_target_io *tio = alloc_tio(ci, ti);
struct bio *clone;
tio->info.flush_request = flush_nr;
clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);
__bio_clone(clone, ci->bio);
clone->bi_destructor = dm_bio_destructor;
__map_bio(ti, clone, tio);
}
static int __clone_and_map_empty_barrier(struct clone_info *ci)
{
unsigned target_nr = 0, flush_nr;
struct dm_target *ti;
while ((ti = dm_table_get_target(ci->map, target_nr++)))
for (flush_nr = 0; flush_nr < ti->num_flush_requests;
flush_nr++)
__flush_target(ci, ti, flush_nr);
ci->sector_count = 0;
return 0;
}
static int __clone_and_map(struct clone_info *ci)
{
struct bio *clone, *bio = ci->bio;
struct dm_target *ti;
sector_t len = 0, max;
struct dm_target_io *tio;
if (unlikely(bio_empty_barrier(bio)))
return __clone_and_map_empty_barrier(ci);
ti = dm_table_find_target(ci->map, ci->sector);
if (!dm_target_is_valid(ti))
return -EIO;
max = max_io_len(ci->md, ci->sector, ti);
/*
* Allocate a target io object.
*/
tio = alloc_tio(ci, ti);
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);
if (!dm_target_is_valid(ti))
return -EIO;
max = max_io_len(ci->md, ci->sector, ti);
tio = alloc_tio(ci, ti);
}
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++;
}
return 0;
}
/*
* Split the bio into several clones and submit it to targets.
*/
static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
{
struct clone_info ci;
int error = 0;
ci.map = dm_get_live_table(md);
if (unlikely(!ci.map)) {
if (!bio_rw_flagged(bio, BIO_RW_BARRIER))
bio_io_error(bio);
else
if (!md->barrier_error)
md->barrier_error = -EIO;
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;
spin_lock_init(&ci.io->endio_lock);
ci.sector = bio->bi_sector;
ci.sector_count = bio_sectors(bio);
if (unlikely(bio_empty_barrier(bio)))
ci.sector_count = 1;
ci.idx = bio->bi_idx;
start_io_acct(ci.io);
while (ci.sector_count && !error)
error = __clone_and_map(&ci);
/* drop the extra reference count */
dec_pending(ci.io, error);
dm_table_put(ci.map);
}
/*-----------------------------------------------------------------
* CRUD END
*---------------------------------------------------------------*/
static int dm_merge_bvec(struct request_queue *q,
struct bvec_merge_data *bvm,
struct bio_vec *biovec)
{
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_live_table(md);
struct dm_target *ti;
sector_t max_sectors;
int max_size = 0;
if (unlikely(!map))
goto out;
ti = dm_table_find_target(map, bvm->bi_sector);
if (!dm_target_is_valid(ti))
goto out_table;
/*
* Find maximum amount of I/O that won't need splitting
*/
max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
(sector_t) BIO_MAX_SECTORS);
max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
if (max_size < 0)
max_size = 0;
/*
* merge_bvec_fn() returns number of bytes
* it can accept at this offset
* max is precomputed maximal io size
*/
if (max_size && ti->type->merge)
max_size = ti->type->merge(ti, bvm, biovec, max_size);
/*
* If the target doesn't support merge method and some of the devices
* provided their merge_bvec method (we know this by looking at
* queue_max_hw_sectors), then we can't allow bios with multiple vector
* entries. So always set max_size to 0, and the code below allows
* just one page.
*/
else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
max_size = 0;
out_table:
dm_table_put(map);
out:
/*
* Always allow an entire first page
*/
if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
max_size = biovec->bv_len;
return max_size;
}
/*
* 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 rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata;
int cpu;
down_read(&md->io_lock);
cpu = part_stat_lock();
part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
part_stat_unlock();
/*
* If we're suspended or the thread is processing barriers
* we have to queue this io for later.
*/
if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
up_read(&md->io_lock);
if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
bio_rw(bio) == READA) {
bio_io_error(bio);
return 0;
}
queue_io(md, bio);
return 0;
}
__split_and_process_bio(md, bio);
up_read(&md->io_lock);
return 0;
}
static int dm_make_request(struct request_queue *q, struct bio *bio)
{
struct mapped_device *md = q->queuedata;
return md->saved_make_request_fn(q, bio); /* call __make_request() */
}
static int dm_request_based(struct mapped_device *md)
{
return blk_queue_stackable(md->queue);
}
static int dm_request(struct request_queue *q, struct bio *bio)
{
struct mapped_device *md = q->queuedata;
if (dm_request_based(md))
return dm_make_request(q, bio);
return _dm_request(q, bio);
}
/*
* Mark this request as flush request, so that dm_request_fn() can
* recognize.
*/
static void dm_rq_prepare_flush(struct request_queue *q, struct request *rq)
{
rq->cmd_type = REQ_TYPE_LINUX_BLOCK;
rq->cmd[0] = REQ_LB_OP_FLUSH;
}
static bool dm_rq_is_flush_request(struct request *rq)
{
if (rq->cmd_type == REQ_TYPE_LINUX_BLOCK &&
rq->cmd[0] == REQ_LB_OP_FLUSH)
return true;
else
return false;
}
void dm_dispatch_request(struct request *rq)
{
int r;
if (blk_queue_io_stat(rq->q))
rq->cmd_flags |= REQ_IO_STAT;
rq->start_time = jiffies;
r = blk_insert_cloned_request(rq->q, rq);
if (r)
dm_complete_request(rq, r);
}
EXPORT_SYMBOL_GPL(dm_dispatch_request);
static void dm_rq_bio_destructor(struct bio *bio)
{
struct dm_rq_clone_bio_info *info = bio->bi_private;
struct mapped_device *md = info->tio->md;
free_bio_info(info);
bio_free(bio, md->bs);
}
static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
void *data)
{
struct dm_rq_target_io *tio = data;
struct mapped_device *md = tio->md;
struct dm_rq_clone_bio_info *info = alloc_bio_info(md);
if (!info)
return -ENOMEM;
info->orig = bio_orig;
info->tio = tio;
bio->bi_end_io = end_clone_bio;
bio->bi_private = info;
bio->bi_destructor = dm_rq_bio_destructor;
return 0;
}
static int setup_clone(struct request *clone, struct request *rq,
struct dm_rq_target_io *tio)
{
int r;
if (dm_rq_is_flush_request(rq)) {
blk_rq_init(NULL, clone);
clone->cmd_type = REQ_TYPE_FS;
clone->cmd_flags |= (REQ_HARDBARRIER | WRITE);
} else {
r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
dm_rq_bio_constructor, tio);
if (r)
return r;
clone->cmd = rq->cmd;
clone->cmd_len = rq->cmd_len;
clone->sense = rq->sense;
clone->buffer = rq->buffer;
}
clone->end_io = end_clone_request;
clone->end_io_data = tio;
return 0;
}
static struct request *clone_rq(struct request *rq, struct mapped_device *md,
gfp_t gfp_mask)
{
struct request *clone;
struct dm_rq_target_io *tio;
tio = alloc_rq_tio(md, gfp_mask);
if (!tio)
return NULL;
tio->md = md;
tio->ti = NULL;
tio->orig = rq;
tio->error = 0;
memset(&tio->info, 0, sizeof(tio->info));
clone = &tio->clone;
if (setup_clone(clone, rq, tio)) {
/* -ENOMEM */
free_rq_tio(tio);
return NULL;
}
return clone;
}
/*
* Called with the queue lock held.
*/
static int dm_prep_fn(struct request_queue *q, struct request *rq)
{
struct mapped_device *md = q->queuedata;
struct request *clone;
if (unlikely(dm_rq_is_flush_request(rq)))
return BLKPREP_OK;
if (unlikely(rq->special)) {
DMWARN("Already has something in rq->special.");
return BLKPREP_KILL;
}
clone = clone_rq(rq, md, GFP_ATOMIC);
if (!clone)
return BLKPREP_DEFER;
rq->special = clone;
rq->cmd_flags |= REQ_DONTPREP;
return BLKPREP_OK;
}
/*
* Returns:
* 0 : the request has been processed (not requeued)
* !0 : the request has been requeued
*/
static int map_request(struct dm_target *ti, struct request *clone,
struct mapped_device *md)
{
int r, requeued = 0;
struct dm_rq_target_io *tio = clone->end_io_data;
/*
* Hold the md reference here for the in-flight I/O.
* We can't rely on the reference count by device opener,
* because the device may be closed during the request completion
* when all bios are completed.
* See the comment in rq_completed() too.
*/
dm_get(md);
tio->ti = ti;
r = ti->type->map_rq(ti, clone, &tio->info);
switch (r) {
case DM_MAPIO_SUBMITTED:
/* The target has taken the I/O to submit by itself later */
break;
case DM_MAPIO_REMAPPED:
/* The target has remapped the I/O so dispatch it */
trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
blk_rq_pos(tio->orig));
dm_dispatch_request(clone);
break;
case DM_MAPIO_REQUEUE:
/* The target wants to requeue the I/O */
dm_requeue_unmapped_request(clone);
requeued = 1;
break;
default:
if (r > 0) {
DMWARN("unimplemented target map return value: %d", r);
BUG();
}
/* The target wants to complete the I/O */
dm_kill_unmapped_request(clone, r);
break;
}
return requeued;
}
/*
* q->request_fn for request-based dm.
* Called with the queue lock held.
*/
static void dm_request_fn(struct request_queue *q)
{
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_live_table(md);
struct dm_target *ti;
struct request *rq, *clone;
/*
* For suspend, check blk_queue_stopped() and increment
* ->pending within a single queue_lock not to increment the
* number of in-flight I/Os after the queue is stopped in
* dm_suspend().
*/
while (!blk_queue_plugged(q) && !blk_queue_stopped(q)) {
rq = blk_peek_request(q);
if (!rq)
goto plug_and_out;
if (unlikely(dm_rq_is_flush_request(rq))) {
BUG_ON(md->flush_request);
md->flush_request = rq;
blk_start_request(rq);
queue_work(md->wq, &md->barrier_work);
goto out;
}
ti = dm_table_find_target(map, blk_rq_pos(rq));
if (ti->type->busy && ti->type->busy(ti))
goto plug_and_out;
blk_start_request(rq);
clone = rq->special;
atomic_inc(&md->pending[rq_data_dir(clone)]);
spin_unlock(q->queue_lock);
if (map_request(ti, clone, md))
goto requeued;
spin_lock_irq(q->queue_lock);
}
goto out;
requeued:
spin_lock_irq(q->queue_lock);
plug_and_out:
if (!elv_queue_empty(q))
/* Some requests still remain, retry later */
blk_plug_device(q);
out:
dm_table_put(map);
return;
}
int dm_underlying_device_busy(struct request_queue *q)
{
return blk_lld_busy(q);
}
EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
static int dm_lld_busy(struct request_queue *q)
{
int r;
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_live_table(md);
if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
r = 1;
else
r = dm_table_any_busy_target(map);
dm_table_put(map);
return r;
}
static void dm_unplug_all(struct request_queue *q)
{
struct mapped_device *md = q->queuedata;
struct dm_table *map = dm_get_live_table(md);
if (map) {
if (dm_request_based(md))
generic_unplug_device(q);
dm_table_unplug_all(map);
dm_table_put(map);
}
}
static int dm_any_congested(void *congested_data, int bdi_bits)
{
int r = bdi_bits;
struct mapped_device *md = congested_data;
struct dm_table *map;
if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
map = dm_get_live_table(md);
if (map) {
/*
* Request-based dm cares about only own queue for
* the query about congestion status of request_queue
*/
if (dm_request_based(md))
r = md->queue->backing_dev_info.state &
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(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(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 const struct block_device_operations dm_blk_dops;
static void dm_wq_work(struct work_struct *work);
static void dm_rq_barrier_work(struct work_struct *work);
/*
* Allocate and initialise a blank device with a given minor.
*/
static struct mapped_device *alloc_dev(int minor)
{
int r;
struct mapped_device *md = kzalloc(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 bad_module_get;
/* get a minor number for the dev */
if (minor == DM_ANY_MINOR)
r = next_free_minor(&minor);
else
r = specific_minor(minor);
if (r < 0)
goto bad_minor;
init_rwsem(&md->io_lock);
mutex_init(&md->suspend_lock);
spin_lock_init(&md->deferred_lock);
spin_lock_init(&md->barrier_error_lock);
rwlock_init(&md->map_lock);
atomic_set(&md->holders, 1);
atomic_set(&md->open_count, 0);
atomic_set(&md->event_nr, 0);
atomic_set(&md->uevent_seq, 0);
INIT_LIST_HEAD(&md->uevent_list);
spin_lock_init(&md->uevent_lock);
md->queue = blk_init_queue(dm_request_fn, NULL);
if (!md->queue)
goto bad_queue;
/*
* Request-based dm devices cannot be stacked on top of bio-based dm
* devices. The type of this dm device has not been decided yet,
* although we initialized the queue using blk_init_queue().
* The type is decided at the first table loading time.
* To prevent problematic device stacking, clear the queue flag
* for request stacking support until then.
*
* This queue is new, so no concurrency on the queue_flags.
*/
queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
md->saved_make_request_fn = md->queue->make_request_fn;
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;
blk_queue_merge_bvec(md->queue, dm_merge_bvec);
blk_queue_softirq_done(md->queue, dm_softirq_done);
blk_queue_prep_rq(md->queue, dm_prep_fn);
blk_queue_lld_busy(md->queue, dm_lld_busy);
blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH,
dm_rq_prepare_flush);
md->disk = alloc_disk(1);
if (!md->disk)
goto bad_disk;
atomic_set(&md->pending[0], 0);
atomic_set(&md->pending[1], 0);
init_waitqueue_head(&md->wait);
INIT_WORK(&md->work, dm_wq_work);
INIT_WORK(&md->barrier_work, dm_rq_barrier_work);
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));
md->wq = create_singlethread_workqueue("kdmflush");
if (!md->wq)
goto bad_thread;
md->bdev = bdget_disk(md->disk, 0);
if (!md->bdev)
goto bad_bdev;
/* 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;
bad_bdev:
destroy_workqueue(md->wq);
bad_thread:
del_gendisk(md->disk);
put_disk(md->disk);
bad_disk:
blk_cleanup_queue(md->queue);
bad_queue:
free_minor(minor);
bad_minor:
module_put(THIS_MODULE);
bad_module_get:
kfree(md);
return NULL;
}
static void unlock_fs(struct mapped_device *md);
static void free_dev(struct mapped_device *md)
{
int minor = MINOR(disk_devt(md->disk));
unlock_fs(md);
bdput(md->bdev);
destroy_workqueue(md->wq);
if (md->tio_pool)
mempool_destroy(md->tio_pool);
if (md->io_pool)
mempool_destroy(md->io_pool);
if (md->bs)
bioset_free(md->bs);
blk_integrity_unregister(md->disk);
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);
}
static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
struct dm_md_mempools *p;
if (md->io_pool && md->tio_pool && md->bs)
/* the md already has necessary mempools */
goto out;
p = dm_table_get_md_mempools(t);
BUG_ON(!p || md->io_pool || md->tio_pool || md->bs);
md->io_pool = p->io_pool;
p->io_pool = NULL;
md->tio_pool = p->tio_pool;
p->tio_pool = NULL;
md->bs = p->bs;
p->bs = NULL;
out:
/* mempool bind completed, now no need any mempools in the table */
dm_table_free_md_mempools(t);
}
/*
* Bind a table to the device.
*/
static void event_callback(void *context)
{
unsigned long flags;
LIST_HEAD(uevents);
struct mapped_device *md = (struct mapped_device *) context;
spin_lock_irqsave(&md->uevent_lock, flags);
list_splice_init(&md->uevent_list, &uevents);
spin_unlock_irqrestore(&md->uevent_lock, flags);
dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
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->bdev->bd_inode->i_mutex);
i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
mutex_unlock(&md->bdev->bd_inode->i_mutex);
}
/*
* Returns old map, which caller must destroy.
*/
static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
struct queue_limits *limits)
{
struct dm_table *old_map;
struct request_queue *q = md->queue;
sector_t size;
unsigned long flags;
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));
__set_size(md, size);
dm_table_event_callback(t, event_callback, md);
/*
* The queue hasn't been stopped yet, if the old table type wasn't
* for request-based during suspension. So stop it to prevent
* I/O mapping before resume.
* This must be done before setting the queue restrictions,
* because request-based dm may be run just after the setting.
*/
if (dm_table_request_based(t) && !blk_queue_stopped(q))
stop_queue(q);
__bind_mempools(md, t);
write_lock_irqsave(&md->map_lock, flags);
old_map = md->map;
md->map = t;
dm_table_set_restrictions(t, q, limits);
write_unlock_irqrestore(&md->map_lock, flags);
return old_map;
}
/*
* Returns unbound table for the caller to free.
*/
static struct dm_table *__unbind(struct mapped_device *md)
{
struct dm_table *map = md->map;
unsigned long flags;
if (!map)
return NULL;
dm_table_event_callback(map, NULL, NULL);
write_lock_irqsave(&md->map_lock, flags);
md->map = NULL;
write_unlock_irqrestore(&md->map_lock, flags);
return 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;
dm_sysfs_init(md);
*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 ||
(MINOR(disk_devt(dm_disk(md))) != 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_live_table(md);
idr_replace(&_minor_idr, MINOR_ALLOCED,
MINOR(disk_devt(dm_disk(md))));
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);
if (!dm_suspended_md(md)) {
dm_table_presuspend_targets(map);
dm_table_postsuspend_targets(map);
}
dm_sysfs_exit(md);
dm_table_put(map);
dm_table_destroy(__unbind(md));
free_dev(md);
}
}
EXPORT_SYMBOL_GPL(dm_put);
static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
{
int r = 0;
DECLARE_WAITQUEUE(wait, current);
dm_unplug_all(md->queue);
add_wait_queue(&md->wait, &wait);
while (1) {
set_current_state(interruptible);
smp_mb();
if (!md_in_flight(md))
break;
if (interruptible == TASK_INTERRUPTIBLE &&
signal_pending(current)) {
r = -EINTR;
break;
}
io_schedule();
}
set_current_state(TASK_RUNNING);
remove_wait_queue(&md->wait, &wait);
return r;
}
static void dm_flush(struct mapped_device *md)
{
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
bio_init(&md->barrier_bio);
md->barrier_bio.bi_bdev = md->bdev;
md->barrier_bio.bi_rw = WRITE_BARRIER;
__split_and_process_bio(md, &md->barrier_bio);
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
}
static void process_barrier(struct mapped_device *md, struct bio *bio)
{
md->barrier_error = 0;
dm_flush(md);
if (!bio_empty_barrier(bio)) {
__split_and_process_bio(md, bio);
dm_flush(md);
}
if (md->barrier_error != DM_ENDIO_REQUEUE)
bio_endio(bio, md->barrier_error);
else {
spin_lock_irq(&md->deferred_lock);
bio_list_add_head(&md->deferred, bio);
spin_unlock_irq(&md->deferred_lock);
}
}
/*
* Process the deferred bios
*/
static void dm_wq_work(struct work_struct *work)
{
struct mapped_device *md = container_of(work, struct mapped_device,
work);
struct bio *c;
down_write(&md->io_lock);
while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
spin_lock_irq(&md->deferred_lock);
c = bio_list_pop(&md->deferred);
spin_unlock_irq(&md->deferred_lock);
if (!c) {
clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
break;
}
up_write(&md->io_lock);
if (dm_request_based(md))
generic_make_request(c);
else {
if (bio_rw_flagged(c, BIO_RW_BARRIER))
process_barrier(md, c);
else
__split_and_process_bio(md, c);
}
down_write(&md->io_lock);
}
up_write(&md->io_lock);
}
static void dm_queue_flush(struct mapped_device *md)
{
clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
smp_mb__after_clear_bit();
queue_work(md->wq, &md->work);
}
static void dm_rq_set_flush_nr(struct request *clone, unsigned flush_nr)
{
struct dm_rq_target_io *tio = clone->end_io_data;
tio->info.flush_request = flush_nr;
}
/* Issue barrier requests to targets and wait for their completion. */
static int dm_rq_barrier(struct mapped_device *md)
{
int i, j;
struct dm_table *map = dm_get_live_table(md);
unsigned num_targets = dm_table_get_num_targets(map);
struct dm_target *ti;
struct request *clone;
md->barrier_error = 0;
for (i = 0; i < num_targets; i++) {
ti = dm_table_get_target(map, i);
for (j = 0; j < ti->num_flush_requests; j++) {
clone = clone_rq(md->flush_request, md, GFP_NOIO);
dm_rq_set_flush_nr(clone, j);
atomic_inc(&md->pending[rq_data_dir(clone)]);
map_request(ti, clone, md);
}
}
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
dm_table_put(map);
return md->barrier_error;
}
static void dm_rq_barrier_work(struct work_struct *work)
{
int error;
struct mapped_device *md = container_of(work, struct mapped_device,
barrier_work);
struct request_queue *q = md->queue;
struct request *rq;
unsigned long flags;
/*
* Hold the md reference here and leave it at the last part so that
* the md can't be deleted by device opener when the barrier request
* completes.
*/
dm_get(md);
error = dm_rq_barrier(md);
rq = md->flush_request;
md->flush_request = NULL;
if (error == DM_ENDIO_REQUEUE) {
spin_lock_irqsave(q->queue_lock, flags);
blk_requeue_request(q, rq);
spin_unlock_irqrestore(q->queue_lock, flags);
} else
blk_end_request_all(rq, error);
blk_run_queue(q);
dm_put(md);
}
/*
* Swap in a new table, returning the old one for the caller to destroy.
*/
struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
{
struct dm_table *map = ERR_PTR(-EINVAL);
struct queue_limits limits;
int r;
mutex_lock(&md->suspend_lock);
/* device must be suspended */
if (!dm_suspended_md(md))
goto out;
r = dm_calculate_queue_limits(table, &limits);
if (r) {
map = ERR_PTR(r);
goto out;
}
/* cannot change the device type, once a table is bound */
if (md->map &&
(dm_table_get_type(md->map) != dm_table_get_type(table))) {
DMWARN("can't change the device type after a table is bound");
goto out;
}
map = __bind(md, table, &limits);
out:
mutex_unlock(&md->suspend_lock);
return map;
}
/*
* 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->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);
return 0;
}
static void unlock_fs(struct mapped_device *md)
{
if (!test_bit(DMF_FROZEN, &md->flags))
return;
thaw_bdev(md->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.
*/
/*
* Suspend mechanism in request-based dm.
*
* 1. Flush all I/Os by lock_fs() if needed.
* 2. Stop dispatching any I/O by stopping the request_queue.
* 3. Wait for all in-flight I/Os to be completed or requeued.
*
* To abort suspend, start the request_queue.
*/
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
{
struct dm_table *map = NULL;
int r = 0;
int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
mutex_lock(&md->suspend_lock);
if (dm_suspended_md(md)) {
r = -EINVAL;
goto out_unlock;
}
map = dm_get_live_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);
/*
* Flush I/O to the device.
* Any I/O submitted after lock_fs() may not be flushed.
* noflush takes precedence over do_lockfs.
* (lock_fs() flushes I/Os and waits for them to complete.)
*/
if (!noflush && do_lockfs) {
r = lock_fs(md);
if (r)
goto out;
}
/*
* Here we must make sure that no processes are submitting requests
* to target drivers i.e. no one may be executing
* __split_and_process_bio. This is called from dm_request and
* dm_wq_work.
*
* To get all processes out of __split_and_process_bio in dm_request,
* we take the write lock. To prevent any process from reentering
* __split_and_process_bio from dm_request, we set
* DMF_QUEUE_IO_TO_THREAD.
*
* To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND
* and call flush_workqueue(md->wq). flush_workqueue will wait until
* dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any
* further calls to __split_and_process_bio from dm_wq_work.
*/
down_write(&md->io_lock);
set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
up_write(&md->io_lock);
/*
* Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which
* can be kicked until md->queue is stopped. So stop md->queue before
* flushing md->wq.
*/
if (dm_request_based(md))
stop_queue(md->queue);
flush_workqueue(md->wq);
/*
* At this point no more requests are entering target request routines.
* We call dm_wait_for_completion to wait for all existing requests
* to finish.
*/
r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
down_write(&md->io_lock);
if (noflush)
clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
up_write(&md->io_lock);
/* were we interrupted ? */
if (r < 0) {
dm_queue_flush(md);
if (dm_request_based(md))
start_queue(md->queue);
unlock_fs(md);
goto out; /* pushback list is already flushed, so skip flush */
}
/*
* If dm_wait_for_completion returned 0, the device is completely
* quiescent now. There is no request-processing activity. All new
* requests are being added to md->deferred list.
*/
set_bit(DMF_SUSPENDED, &md->flags);
dm_table_postsuspend_targets(map);
out:
dm_table_put(map);
out_unlock:
mutex_unlock(&md->suspend_lock);
return r;
}
int dm_resume(struct mapped_device *md)
{
int r = -EINVAL;
struct dm_table *map = NULL;
mutex_lock(&md->suspend_lock);
if (!dm_suspended_md(md))
goto out;
map = dm_get_live_table(md);
if (!map || !dm_table_get_size(map))
goto out;
r = dm_table_resume_targets(map);
if (r)
goto out;
dm_queue_flush(md);
/*
* Flushing deferred I/Os must be done after targets are resumed
* so that mapping of targets can work correctly.
* Request-based dm is queueing the deferred I/Os in its request_queue.
*/
if (dm_request_based(md))
start_queue(md->queue);
unlock_fs(md);
clear_bit(DMF_SUSPENDED, &md->flags);
dm_table_unplug_all(map);
r = 0;
out:
dm_table_put(map);
mutex_unlock(&md->suspend_lock);
return r;
}
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/
void dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
unsigned cookie)
{
char udev_cookie[DM_COOKIE_LENGTH];
char *envp[] = { udev_cookie, NULL };
if (!cookie)
kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
else {
snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
DM_COOKIE_ENV_VAR_NAME, cookie);
kobject_uevent_env(&disk_to_dev(md->disk)->kobj, action, envp);
}
}
uint32_t dm_next_uevent_seq(struct mapped_device *md)
{
return atomic_add_return(1, &md->uevent_seq);
}
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)));
}
void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
{
unsigned long flags;
spin_lock_irqsave(&md->uevent_lock, flags);
list_add(elist, &md->uevent_list);
spin_unlock_irqrestore(&md->uevent_lock, flags);
}
/*
* 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;
}
struct kobject *dm_kobject(struct mapped_device *md)
{
return &md->kobj;
}
/*
* struct mapped_device should not be exported outside of dm.c
* so use this check to verify that kobj is part of md structure
*/
struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
{
struct mapped_device *md;
md = container_of(kobj, struct mapped_device, kobj);
if (&md->kobj != kobj)
return NULL;
if (test_bit(DMF_FREEING, &md->flags) ||
dm_deleting_md(md))
return NULL;
dm_get(md);
return md;
}
int dm_suspended_md(struct mapped_device *md)
{
return test_bit(DMF_SUSPENDED, &md->flags);
}
int dm_suspended(struct dm_target *ti)
{
struct mapped_device *md = dm_table_get_md(ti->table);
int r = dm_suspended_md(md);
dm_put(md);
return r;
}
EXPORT_SYMBOL_GPL(dm_suspended);
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);
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type)
{
struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);
if (!pools)
return NULL;
pools->io_pool = (type == DM_TYPE_BIO_BASED) ?
mempool_create_slab_pool(MIN_IOS, _io_cache) :
mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache);
if (!pools->io_pool)
goto free_pools_and_out;
pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?
mempool_create_slab_pool(MIN_IOS, _tio_cache) :
mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);
if (!pools->tio_pool)
goto free_io_pool_and_out;
pools->bs = (type == DM_TYPE_BIO_BASED) ?
bioset_create(16, 0) : bioset_create(MIN_IOS, 0);
if (!pools->bs)
goto free_tio_pool_and_out;
return pools;
free_tio_pool_and_out:
mempool_destroy(pools->tio_pool);
free_io_pool_and_out:
mempool_destroy(pools->io_pool);
free_pools_and_out:
kfree(pools);
return NULL;
}
void dm_free_md_mempools(struct dm_md_mempools *pools)
{
if (!pools)
return;
if (pools->io_pool)
mempool_destroy(pools->io_pool);
if (pools->tio_pool)
mempool_destroy(pools->tio_pool);
if (pools->bs)
bioset_free(pools->bs);
kfree(pools);
}
static const 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");