linux/drivers/md/dm.c
Mike Snitzer 3ae7065616 dm: retain table limits when swapping to new table with no devices
Add a safety net that will re-use the DM device's existing limits in the
event that DM device has a temporary table that doesn't have any
component devices.  This is to reduce the chance that requests not
respecting the hardware limits will reach the device.

DM recalculates queue limits based only on devices which currently exist
in the table.  This creates a problem in the event all devices are
temporarily removed such as all paths being lost in multipath.  DM will
reset the limits to the maximum permissible, which can then assemble
requests which exceed the limits of the paths when the paths are
restored.  The request will fail the blk_rq_check_limits() test when
sent to a path with lower limits, and will be retried without end by
multipath.  This became a much bigger issue after v3.6 commit fe86cdcef
("block: do not artificially constrain max_sectors for stacking
drivers").

Reported-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-09-26 23:45:45 +01:00

2836 lines
62 KiB
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/mempool.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/hdreg.h>
#include <linux/delay.h>
#include <trace/events/block.h>
#define DM_MSG_PREFIX "core"
#ifdef CONFIG_PRINTK
/*
* ratelimit state to be used in DMXXX_LIMIT().
*/
DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
EXPORT_SYMBOL(dm_ratelimit_state);
#endif
/*
* 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_IDR(_minor_idr);
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_MERGE_IS_OPTIONAL 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;
unsigned type;
/* Protect queue and type against concurrent access. */
struct mutex type_lock;
struct target_type *immutable_target_type;
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;
/*
* Processing queue (flush)
*/
struct workqueue_struct *wq;
/*
* 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;
/* sysfs handle */
struct kobject kobj;
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_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]();
/*
* Should be empty by this point.
*/
idr_remove_all(&_minor_idr);
idr_destroy(&_minor_idr);
}
/*
* 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;
spin_lock(&_minor_lock);
atomic_dec(&md->open_count);
dm_put(md);
spin_unlock(&_minor_lock);
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();
atomic_set(&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 flush.
*/
pending = atomic_dec_return(&md->pending[rw]);
atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
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)
{
unsigned long flags;
spin_lock_irqsave(&md->deferred_lock, flags);
bio_list_add(&md->deferred, bio);
spin_unlock_irqrestore(&md->deferred_lock, flags);
queue_work(md->wq, &md->work);
}
/*
* 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))
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;
end_io_acct(io);
free_io(md, io);
if (io_error == DM_ENDIO_REQUEUE)
return;
if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
/*
* Preflush done for flush with data, reissue
* without REQ_FLUSH.
*/
bio->bi_rw &= ~REQ_FLUSH;
queue_io(md, bio);
} else {
/* done with normal IO or empty flush */
trace_block_bio_complete(md->queue, bio, io_error);
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);
}
/*
* 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);
struct dm_rq_target_io *tio = clone->end_io_data;
struct mapped_device *md = tio->md;
struct request *rq = tio->orig;
if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
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);
blk_end_request_all(rq, error);
rq_completed(md, rw, true);
}
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;
dm_unprep_request(rq);
spin_lock_irqsave(q->queue_lock, flags);
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 = NULL;
if (tio->ti) {
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;
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;
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);
}
/*
* Return maximum size of I/O possible at the supplied sector up to the current
* target boundary.
*/
static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
{
sector_t target_offset = dm_target_offset(ti, sector);
return ti->len - target_offset;
}
static sector_t max_io_len(sector_t sector, struct dm_target *ti)
{
sector_t len = max_io_len_target_boundary(sector, ti);
sector_t offset, max_len;
/*
* Does the target need to split even further?
*/
if (ti->max_io_len) {
offset = dm_target_offset(ti, sector);
if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
max_len = sector_div(offset, ti->max_io_len);
else
max_len = offset & (ti->max_io_len - 1);
max_len = ti->max_io_len - max_len;
if (len > max_len)
len = max_len;
}
return len;
}
int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
{
if (len > UINT_MAX) {
DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
(unsigned long long)len, UINT_MAX);
ti->error = "Maximum size of target IO is too large";
return -EINVAL;
}
ti->max_io_len = (uint32_t) len;
return 0;
}
EXPORT_SYMBOL_GPL(dm_set_target_max_io_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_bio_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_end_io = NULL;
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 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;
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_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 __issue_target_request(struct clone_info *ci, struct dm_target *ti,
unsigned request_nr, sector_t len)
{
struct dm_target_io *tio = alloc_tio(ci, ti);
struct bio *clone;
tio->info.target_request_nr = request_nr;
/*
* Discard requests require the bio's inline iovecs be initialized.
* ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
* and discard, so no need for concern about wasted bvec allocations.
*/
clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs);
__bio_clone(clone, ci->bio);
clone->bi_destructor = dm_bio_destructor;
if (len) {
clone->bi_sector = ci->sector;
clone->bi_size = to_bytes(len);
}
__map_bio(ti, clone, tio);
}
static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
unsigned num_requests, sector_t len)
{
unsigned request_nr;
for (request_nr = 0; request_nr < num_requests; request_nr++)
__issue_target_request(ci, ti, request_nr, len);
}
static int __clone_and_map_empty_flush(struct clone_info *ci)
{
unsigned target_nr = 0;
struct dm_target *ti;
BUG_ON(bio_has_data(ci->bio));
while ((ti = dm_table_get_target(ci->map, target_nr++)))
__issue_target_requests(ci, ti, ti->num_flush_requests, 0);
return 0;
}
/*
* Perform all io with a single clone.
*/
static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)
{
struct bio *clone, *bio = ci->bio;
struct dm_target_io *tio;
tio = alloc_tio(ci, ti);
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;
}
static int __clone_and_map_discard(struct clone_info *ci)
{
struct dm_target *ti;
sector_t len;
do {
ti = dm_table_find_target(ci->map, ci->sector);
if (!dm_target_is_valid(ti))
return -EIO;
/*
* Even though the device advertised discard support,
* that does not mean every target supports it, and
* reconfiguration might also have changed that since the
* check was performed.
*/
if (!ti->num_discard_requests)
return -EOPNOTSUPP;
if (!ti->split_discard_requests)
len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
else
len = min(ci->sector_count, max_io_len(ci->sector, ti));
__issue_target_requests(ci, ti, ti->num_discard_requests, len);
ci->sector += len;
} while (ci->sector_count -= len);
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->bi_rw & REQ_DISCARD))
return __clone_and_map_discard(ci);
ti = dm_table_find_target(ci->map, ci->sector);
if (!dm_target_is_valid(ti))
return -EIO;
max = max_io_len(ci->sector, 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_and_map_simple(ci, ti);
} 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;
}
tio = alloc_tio(ci, ti);
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->sector, ti);
}
len = min(remaining, max);
tio = alloc_tio(ci, ti);
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)) {
bio_io_error(bio);
return;
}
ci.md = md;
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.idx = bio->bi_idx;
start_io_acct(ci.io);
if (bio->bi_rw & REQ_FLUSH) {
ci.bio = &ci.md->flush_bio;
ci.sector_count = 0;
error = __clone_and_map_empty_flush(&ci);
/* dec_pending submits any data associated with flush */
} else {
ci.bio = bio;
ci.sector_count = bio_sectors(bio);
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(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 void _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, we have to queue this io for later */
if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
up_read(&md->io_lock);
if (bio_rw(bio) != READA)
queue_io(md, bio);
else
bio_io_error(bio);
return;
}
__split_and_process_bio(md, bio);
up_read(&md->io_lock);
return;
}
static int dm_request_based(struct mapped_device *md)
{
return blk_queue_stackable(md->queue);
}
static void dm_request(struct request_queue *q, struct bio *bio)
{
struct mapped_device *md = q->queuedata;
if (dm_request_based(md))
blk_queue_bio(q, bio);
else
_dm_request(q, bio);
}
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;
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(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;
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;
}
static struct request *dm_start_request(struct mapped_device *md, struct request *orig)
{
struct request *clone;
blk_start_request(orig);
clone = orig->special;
atomic_inc(&md->pending[rq_data_dir(clone)]);
/*
* 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);
return clone;
}
/*
* 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;
sector_t pos;
/*
* 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_stopped(q)) {
rq = blk_peek_request(q);
if (!rq)
goto delay_and_out;
/* always use block 0 to find the target for flushes for now */
pos = 0;
if (!(rq->cmd_flags & REQ_FLUSH))
pos = blk_rq_pos(rq);
ti = dm_table_find_target(map, pos);
if (!dm_target_is_valid(ti)) {
/*
* Must perform setup, that dm_done() requires,
* before calling dm_kill_unmapped_request
*/
DMERR_LIMIT("request attempted access beyond the end of device");
clone = dm_start_request(md, rq);
dm_kill_unmapped_request(clone, -EIO);
continue;
}
if (ti->type->busy && ti->type->busy(ti))
goto delay_and_out;
clone = dm_start_request(md, rq);
spin_unlock(q->queue_lock);
if (map_request(ti, clone, md))
goto requeued;
BUG_ON(!irqs_disabled());
spin_lock(q->queue_lock);
}
goto out;
requeued:
BUG_ON(!irqs_disabled());
spin_lock(q->queue_lock);
delay_and_out:
blk_delay_queue(q, HZ / 10);
out:
dm_table_put(map);
}
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 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 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_init_md_queue(struct mapped_device *md)
{
/*
* 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.
* 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->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);
blk_queue_merge_bvec(md->queue, dm_merge_bvec);
}
/*
* 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;
md->type = DM_TYPE_NONE;
init_rwsem(&md->io_lock);
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
spin_lock_init(&md->deferred_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_alloc_queue(GFP_KERNEL);
if (!md->queue)
goto bad_queue;
dm_init_md_queue(md);
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_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 = alloc_workqueue("kdmflush",
WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
if (!md->wq)
goto bad_thread;
md->bdev = bdget_disk(md->disk, 0);
if (!md->bdev)
goto bad_bdev;
bio_init(&md->flush_bio);
md->flush_bio.bi_bdev = md->bdev;
md->flush_bio.bi_rw = WRITE_FLUSH;
/* 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);
}
/*
* Protected by md->suspend_lock obtained by dm_swap_table().
*/
static void __set_size(struct mapped_device *md, sector_t size)
{
set_capacity(md->disk, size);
i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
}
/*
* Return 1 if the queue has a compulsory merge_bvec_fn function.
*
* If this function returns 0, then the device is either a non-dm
* device without a merge_bvec_fn, or it is a dm device that is
* able to split any bios it receives that are too big.
*/
int dm_queue_merge_is_compulsory(struct request_queue *q)
{
struct mapped_device *dev_md;
if (!q->merge_bvec_fn)
return 0;
if (q->make_request_fn == dm_request) {
dev_md = q->queuedata;
if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
return 0;
}
return 1;
}
static int dm_device_merge_is_compulsory(struct dm_target *ti,
struct dm_dev *dev, sector_t start,
sector_t len, void *data)
{
struct block_device *bdev = dev->bdev;
struct request_queue *q = bdev_get_queue(bdev);
return dm_queue_merge_is_compulsory(q);
}
/*
* Return 1 if it is acceptable to ignore merge_bvec_fn based
* on the properties of the underlying devices.
*/
static int dm_table_merge_is_optional(struct dm_table *table)
{
unsigned i = 0;
struct dm_target *ti;
while (i < dm_table_get_num_targets(table)) {
ti = dm_table_get_target(table, i++);
if (ti->type->iterate_devices &&
ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
return 0;
}
return 1;
}
/*
* 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;
int merge_is_optional;
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);
merge_is_optional = dm_table_merge_is_optional(t);
write_lock_irqsave(&md->map_lock, flags);
old_map = md->map;
md->map = t;
md->immutable_target_type = dm_table_get_immutable_target_type(t);
dm_table_set_restrictions(t, q, limits);
if (merge_is_optional)
set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
else
clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
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;
}
/*
* Functions to manage md->type.
* All are required to hold md->type_lock.
*/
void dm_lock_md_type(struct mapped_device *md)
{
mutex_lock(&md->type_lock);
}
void dm_unlock_md_type(struct mapped_device *md)
{
mutex_unlock(&md->type_lock);
}
void dm_set_md_type(struct mapped_device *md, unsigned type)
{
md->type = type;
}
unsigned dm_get_md_type(struct mapped_device *md)
{
return md->type;
}
struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
{
return md->immutable_target_type;
}
/*
* Fully initialize a request-based queue (->elevator, ->request_fn, etc).
*/
static int dm_init_request_based_queue(struct mapped_device *md)
{
struct request_queue *q = NULL;
if (md->queue->elevator)
return 1;
/* Fully initialize the queue */
q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
if (!q)
return 0;
md->queue = q;
dm_init_md_queue(md);
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);
elv_register_queue(md->queue);
return 1;
}
/*
* Setup the DM device's queue based on md's type
*/
int dm_setup_md_queue(struct mapped_device *md)
{
if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
!dm_init_request_based_queue(md)) {
DMWARN("Cannot initialize queue for request-based mapped device");
return -EINVAL;
}
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) ||
dm_deleting_md(md) ||
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;
}
EXPORT_SYMBOL_GPL(dm_get_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);
BUG_ON(test_bit(DMF_FREEING, &md->flags));
}
const char *dm_device_name(struct mapped_device *md)
{
return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);
static void __dm_destroy(struct mapped_device *md, bool wait)
{
struct dm_table *map;
might_sleep();
spin_lock(&_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);
}
/*
* Rare, but there may be I/O requests still going to complete,
* for example. Wait for all references to disappear.
* No one should increment the reference count of the mapped_device,
* after the mapped_device state becomes DMF_FREEING.
*/
if (wait)
while (atomic_read(&md->holders))
msleep(1);
else if (atomic_read(&md->holders))
DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
dm_device_name(md), atomic_read(&md->holders));
dm_sysfs_exit(md);
dm_table_put(map);
dm_table_destroy(__unbind(md));
free_dev(md);
}
void dm_destroy(struct mapped_device *md)
{
__dm_destroy(md, true);
}
void dm_destroy_immediate(struct mapped_device *md)
{
__dm_destroy(md, false);
}
void dm_put(struct mapped_device *md)
{
atomic_dec(&md->holders);
}
EXPORT_SYMBOL_GPL(dm_put);
static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
{
int r = 0;
DECLARE_WAITQUEUE(wait, current);
add_wait_queue(&md->wait, &wait);
while (1) {
set_current_state(interruptible);
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;
}
/*
* 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_read(&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)
break;
up_read(&md->io_lock);
if (dm_request_based(md))
generic_make_request(c);
else
__split_and_process_bio(md, c);
down_read(&md->io_lock);
}
up_read(&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);
}
/*
* 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 *live_map, *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;
/*
* If the new table has no data devices, retain the existing limits.
* This helps multipath with queue_if_no_path if all paths disappear,
* then new I/O is queued based on these limits, and then some paths
* reappear.
*/
if (dm_table_has_no_data_devices(table)) {
live_map = dm_get_live_table(md);
if (live_map)
limits = md->queue->limits;
dm_table_put(live_map);
}
r = dm_calculate_queue_limits(table, &limits);
if (r) {
map = ERR_PTR(r);
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 and quiesce the thread
* (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
* flush_workqueue(md->wq).
*/
down_write(&md->io_lock);
set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
up_write(&md->io_lock);
/*
* Stop md->queue before flushing md->wq in case request-based
* dm defers requests to md->wq from md->queue.
*/
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);
r = 0;
out:
dm_table_put(map);
mutex_unlock(&md->suspend_lock);
return r;
}
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/
int 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)
return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
else {
snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
DM_COOKIE_ENV_VAR_NAME, cookie);
return 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)
{
return dm_suspended_md(dm_table_get_md(ti->table));
}
EXPORT_SYMBOL_GPL(dm_suspended);
int dm_noflush_suspending(struct dm_target *ti)
{
return __noflush_suspending(dm_table_get_md(ti->table));
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity)
{
struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);
unsigned int pool_size = (type == DM_TYPE_BIO_BASED) ? 16 : MIN_IOS;
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 = bioset_create(pool_size, 0);
if (!pools->bs)
goto free_tio_pool_and_out;
if (integrity && bioset_integrity_create(pools->bs, pool_size))
goto free_bioset_and_out;
return pools;
free_bioset_and_out:
bioset_free(pools->bs);
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");