Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm (6f97b220) · Commits · 戴 / test

Documentation/device-mapper/dm-crypt.txt

0 → 100644

+52 −0

Original line number	Diff line number	Diff line
		dm-crypt
		=========

		Device-Mapper's "crypt" target provides transparent encryption of block devices
		using the kernel crypto API.

		Parameters: <cipher> <key> <iv_offset> <device path> <offset>

		<cipher>
		Encryption cipher and an optional IV generation mode.
		(In format cipher-chainmode-ivopts:ivmode).
		Examples:
		des
		aes-cbc-essiv:sha256
		twofish-ecb

		/proc/crypto contains supported crypto modes

		<key>
		Key used for encryption. It is encoded as a hexadecimal number.
		You can only use key sizes that are valid for the selected cipher.

		<iv_offset>
		The IV offset is a sector count that is added to the sector number
		before creating the IV.

		<device path>
		This is the device that is going to be used as backend and contains the
		encrypted data. You can specify it as a path like /dev/xxx or a device
		number <major>:<minor>.

		<offset>
		Starting sector within the device where the encrypted data begins.

		Example scripts
		===============
		LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
		encryption with dm-crypt using the 'cryptsetup' utility, see
		http://luks.endorphin.org/

		[[
		#!/bin/sh
		# Create a crypt device using dmsetup
		dmsetup create crypt1 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
		]]

		[[
		#!/bin/sh
		# Create a crypt device using cryptsetup and LUKS header with default cipher
		cryptsetup luksFormat $1
		cryptsetup luksOpen $1 crypt1
		]]

drivers/md/Makefile

+3 −3

Original line number	Diff line number	Diff line
		@@ -3,10 +3,10 @@
		#

		dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
		dm-ioctl.o dm-io.o kcopyd.o
		dm-ioctl.o dm-io.o dm-kcopyd.o
		dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
		dm-snapshot-objs := dm-snap.o dm-exception-store.o
		dm-mirror-objs := dm-log.o dm-raid1.o
		dm-mirror-objs := dm-raid1.o
		dm-rdac-objs := dm-mpath-rdac.o
		dm-hp-sw-objs := dm-mpath-hp-sw.o
		md-mod-objs := md.o bitmap.o
		@@ -39,7 +39,7 @@ obj-$(CONFIG_DM_MULTIPATH_EMC) += dm-emc.o
		obj-$(CONFIG_DM_MULTIPATH_HP) += dm-hp-sw.o
		obj-$(CONFIG_DM_MULTIPATH_RDAC) += dm-rdac.o
		obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
		obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
		obj-$(CONFIG_DM_MIRROR) += dm-mirror.o dm-log.o
		obj-$(CONFIG_DM_ZERO) += dm-zero.o

		quiet_cmd_unroll = UNROLL $@

drivers/md/dm-exception-store.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -9,13 +9,13 @@

		#include "dm.h"
		#include "dm-snap.h"
		#include "dm-io.h"
		#include "kcopyd.h"

		#include <linux/mm.h>
		#include <linux/pagemap.h>
		#include <linux/vmalloc.h>
		#include <linux/slab.h>
		#include <linux/dm-io.h>
		#include <linux/dm-kcopyd.h>

		#define DM_MSG_PREFIX "snapshots"
		#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */
		@@ -131,7 +131,7 @@ struct pstore {

		static unsigned sectors_to_pages(unsigned sectors)
		{
		return sectors / (PAGE_SIZE >> 9);
		return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9);
		}

		static int alloc_area(struct pstore *ps)
		@@ -159,7 +159,7 @@ static void free_area(struct pstore *ps)
		}

		struct mdata_req {
		struct io_region *where;
		struct dm_io_region *where;
		struct dm_io_request *io_req;
		struct work_struct work;
		int result;
		@@ -177,7 +177,7 @@ static void do_metadata(struct work_struct *work)
		*/
		static int chunk_io(struct pstore *ps, uint32_t chunk, int rw, int metadata)
		{
		struct io_region where = {
		struct dm_io_region where = {
		.bdev = ps->snap->cow->bdev,
		.sector = ps->snap->chunk_size * chunk,
		.count = ps->snap->chunk_size,

drivers/md/dm-io.c

+22 −16

Original line number	Diff line number	Diff line
		@@ -5,13 +5,14 @@
		* This file is released under the GPL.
		*/

		#include "dm-io.h"
		#include "dm.h"

		#include <linux/bio.h>
		#include <linux/mempool.h>
		#include <linux/module.h>
		#include <linux/sched.h>
		#include <linux/slab.h>
		#include <linux/dm-io.h>

		struct dm_io_client {
		mempool_t *pool;
		@@ -20,7 +21,7 @@ struct dm_io_client {

		/* FIXME: can we shrink this ? */
		struct io {
		unsigned long error;
		unsigned long error_bits;
		atomic_t count;
		struct task_struct *sleeper;
		struct dm_io_client *client;
		@@ -107,14 +108,14 @@ static inline unsigned bio_get_region(struct bio *bio)
		static void dec_count(struct io *io, unsigned int region, int error)
		{
		if (error)
		set_bit(region, &io->error);
		set_bit(region, &io->error_bits);

		if (atomic_dec_and_test(&io->count)) {
		if (io->sleeper)
		wake_up_process(io->sleeper);

		else {
		unsigned long r = io->error;
		unsigned long r = io->error_bits;
		io_notify_fn fn = io->callback;
		void *context = io->context;

		@@ -271,7 +272,7 @@ static void km_dp_init(struct dpages dp, void data)
		/*-----------------------------------------------------------------
		* IO routines that accept a list of pages.
		---------------------------------------------------------------/
		static void do_region(int rw, unsigned int region, struct io_region *where,
		static void do_region(int rw, unsigned region, struct dm_io_region *where,
		struct dpages dp, struct io io)
		{
		struct bio *bio;
		@@ -320,7 +321,7 @@ static void do_region(int rw, unsigned int region, struct io_region *where,
		}

		static void dispatch_io(int rw, unsigned int num_regions,
		struct io_region where, struct dpages dp,
		struct dm_io_region where, struct dpages dp,
		struct io *io, int sync)
		{
		int i;
		@@ -347,17 +348,17 @@ static void dispatch_io(int rw, unsigned int num_regions,
		}

		static int sync_io(struct dm_io_client *client, unsigned int num_regions,
		struct io_region where, int rw, struct dpages dp,
		struct dm_io_region where, int rw, struct dpages dp,
		unsigned long *error_bits)
		{
		struct io io;

		if (num_regions > 1 && rw != WRITE) {
		if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
		WARN_ON(1);
		return -EIO;
		}

		io.error = 0;
		io.error_bits = 0;
		atomic_set(&io.count, 1); /* see dispatch_io() */
		io.sleeper = current;
		io.client = client;
		@@ -378,25 +379,25 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
		return -EINTR;

		if (error_bits)
		*error_bits = io.error;
		*error_bits = io.error_bits;

		return io.error ? -EIO : 0;
		return io.error_bits ? -EIO : 0;
		}

		static int async_io(struct dm_io_client *client, unsigned int num_regions,
		struct io_region where, int rw, struct dpages dp,
		struct dm_io_region where, int rw, struct dpages dp,
		io_notify_fn fn, void *context)
		{
		struct io *io;

		if (num_regions > 1 && rw != WRITE) {
		if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
		WARN_ON(1);
		fn(1, context);
		return -EIO;
		}

		io = mempool_alloc(client->pool, GFP_NOIO);
		io->error = 0;
		io->error_bits = 0;
		atomic_set(&io->count, 1); /* see dispatch_io() */
		io->sleeper = NULL;
		io->client = client;
		@@ -435,10 +436,15 @@ static int dp_init(struct dm_io_request io_req, struct dpages dp)
		}

		/*
		* New collapsed (a)synchronous interface
		* New collapsed (a)synchronous interface.
		*
		* If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
		* the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in
		* io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
		* the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
		*/
		int dm_io(struct dm_io_request *io_req, unsigned num_regions,
		struct io_region where, unsigned long sync_error_bits)
		struct dm_io_region where, unsigned long sync_error_bits)
		{
		int r;
		struct dpages dp;

drivers/md/kcopyd.c→drivers/md/dm-kcopyd.c

+122 −176

Original line number	Diff line number	Diff line
		@@ -9,9 +9,8 @@
		* completion notification.
		*/

		#include <asm/types.h>
		#include <linux/types.h>
		#include <asm/atomic.h>

		#include <linux/blkdev.h>
		#include <linux/fs.h>
		#include <linux/init.h>
		@@ -23,24 +22,15 @@
		#include <linux/vmalloc.h>
		#include <linux/workqueue.h>
		#include <linux/mutex.h>
		#include <linux/dm-kcopyd.h>

		#include "kcopyd.h"

		static struct workqueue_struct *_kcopyd_wq;
		static struct work_struct _kcopyd_work;

		static void wake(void)
		{
		queue_work(_kcopyd_wq, &_kcopyd_work);
		}
		#include "dm.h"

		/*-----------------------------------------------------------------
		* Each kcopyd client has its own little pool of preallocated
		* pages for kcopyd io.
		---------------------------------------------------------------/
		struct kcopyd_client {
		struct list_head list;

		struct dm_kcopyd_client {
		spinlock_t lock;
		struct page_list *pages;
		unsigned int nr_pages;
		@@ -50,8 +40,32 @@ struct kcopyd_client {

		wait_queue_head_t destroyq;
		atomic_t nr_jobs;

		mempool_t *job_pool;

		struct workqueue_struct *kcopyd_wq;
		struct work_struct kcopyd_work;

		/*
		* We maintain three lists of jobs:
		*
		* i) jobs waiting for pages
		* ii) jobs that have pages, and are waiting for the io to be issued.
		* iii) jobs that have completed.
		*
		* All three of these are protected by job_lock.
		*/
		spinlock_t job_lock;
		struct list_head complete_jobs;
		struct list_head io_jobs;
		struct list_head pages_jobs;
		};

		static void wake(struct dm_kcopyd_client *kc)
		{
		queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
		}

		static struct page_list *alloc_pl(void)
		{
		struct page_list *pl;
		@@ -75,7 +89,7 @@ static void free_pl(struct page_list *pl)
		kfree(pl);
		}

		static int kcopyd_get_pages(struct kcopyd_client *kc,
		static int kcopyd_get_pages(struct dm_kcopyd_client *kc,
		unsigned int nr, struct page_list **pages)
		{
		struct page_list *pl;
		@@ -98,7 +112,7 @@ static int kcopyd_get_pages(struct kcopyd_client *kc,
		return 0;
		}

		static void kcopyd_put_pages(struct kcopyd_client kc, struct page_list pl)
		static void kcopyd_put_pages(struct dm_kcopyd_client kc, struct page_list pl)
		{
		struct page_list *cursor;

		@@ -126,7 +140,7 @@ static void drop_pages(struct page_list *pl)
		}
		}

		static int client_alloc_pages(struct kcopyd_client *kc, unsigned int nr)
		static int client_alloc_pages(struct dm_kcopyd_client *kc, unsigned int nr)
		{
		unsigned int i;
		struct page_list pl = NULL, next;
		@@ -147,7 +161,7 @@ static int client_alloc_pages(struct kcopyd_client *kc, unsigned int nr)
		return 0;
		}

		static void client_free_pages(struct kcopyd_client *kc)
		static void client_free_pages(struct dm_kcopyd_client *kc)
		{
		BUG_ON(kc->nr_free_pages != kc->nr_pages);
		drop_pages(kc->pages);
		@@ -161,7 +175,7 @@ static void client_free_pages(struct kcopyd_client *kc)
		* ever having to do io (which could cause a deadlock).
		---------------------------------------------------------------/
		struct kcopyd_job {
		struct kcopyd_client *kc;
		struct dm_kcopyd_client *kc;
		struct list_head list;
		unsigned long flags;

		@@ -175,13 +189,13 @@ struct kcopyd_job {
		* Either READ or WRITE
		*/
		int rw;
		struct io_region source;
		struct dm_io_region source;

		/*
		* The destinations for the transfer.
		*/
		unsigned int num_dests;
		struct io_region dests[KCOPYD_MAX_REGIONS];
		struct dm_io_region dests[DM_KCOPYD_MAX_REGIONS];

		sector_t offset;
		unsigned int nr_pages;
		@@ -191,7 +205,7 @@ struct kcopyd_job {
		* Set this to ensure you are notified when the job has
		* completed. 'context' is for callback to use.
		*/
		kcopyd_notify_fn fn;
		dm_kcopyd_notify_fn fn;
		void *context;

		/*
		@@ -207,47 +221,19 @@ struct kcopyd_job {
		#define MIN_JOBS 512

		static struct kmem_cache *_job_cache;
		static mempool_t *_job_pool;

		/*
		* We maintain three lists of jobs:
		*
		* i) jobs waiting for pages
		* ii) jobs that have pages, and are waiting for the io to be issued.
		* iii) jobs that have completed.
		*
		* All three of these are protected by job_lock.
		*/
		static DEFINE_SPINLOCK(_job_lock);

		static LIST_HEAD(_complete_jobs);
		static LIST_HEAD(_io_jobs);
		static LIST_HEAD(_pages_jobs);

		static int jobs_init(void)
		int __init dm_kcopyd_init(void)
		{
		_job_cache = KMEM_CACHE(kcopyd_job, 0);
		if (!_job_cache)
		return -ENOMEM;

		_job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
		if (!_job_pool) {
		kmem_cache_destroy(_job_cache);
		return -ENOMEM;
		}

		return 0;
		}

		static void jobs_exit(void)
		void dm_kcopyd_exit(void)
		{
		BUG_ON(!list_empty(&_complete_jobs));
		BUG_ON(!list_empty(&_io_jobs));
		BUG_ON(!list_empty(&_pages_jobs));

		mempool_destroy(_job_pool);
		kmem_cache_destroy(_job_cache);
		_job_pool = NULL;
		_job_cache = NULL;
		}

		@@ -255,18 +241,19 @@ static void jobs_exit(void)
		* Functions to push and pop a job onto the head of a given job
		* list.
		*/
		static struct kcopyd_job pop(struct list_head jobs)
		static struct kcopyd_job pop(struct list_head jobs,
		struct dm_kcopyd_client *kc)
		{
		struct kcopyd_job *job = NULL;
		unsigned long flags;

		spin_lock_irqsave(&_job_lock, flags);
		spin_lock_irqsave(&kc->job_lock, flags);

		if (!list_empty(jobs)) {
		job = list_entry(jobs->next, struct kcopyd_job, list);
		list_del(&job->list);
		}
		spin_unlock_irqrestore(&_job_lock, flags);
		spin_unlock_irqrestore(&kc->job_lock, flags);

		return job;
		}
		@@ -274,10 +261,11 @@ static struct kcopyd_job pop(struct list_head jobs)
		static void push(struct list_head jobs, struct kcopyd_job job)
		{
		unsigned long flags;
		struct dm_kcopyd_client *kc = job->kc;

		spin_lock_irqsave(&_job_lock, flags);
		spin_lock_irqsave(&kc->job_lock, flags);
		list_add_tail(&job->list, jobs);
		spin_unlock_irqrestore(&_job_lock, flags);
		spin_unlock_irqrestore(&kc->job_lock, flags);
		}

		/*
		@@ -294,11 +282,11 @@ static int run_complete_job(struct kcopyd_job *job)
		void *context = job->context;
		int read_err = job->read_err;
		unsigned long write_err = job->write_err;
		kcopyd_notify_fn fn = job->fn;
		struct kcopyd_client *kc = job->kc;
		dm_kcopyd_notify_fn fn = job->fn;
		struct dm_kcopyd_client *kc = job->kc;

		kcopyd_put_pages(kc, job->pages);
		mempool_free(job, _job_pool);
		mempool_free(job, kc->job_pool);
		fn(read_err, write_err, context);

		if (atomic_dec_and_test(&kc->nr_jobs))
		@@ -310,6 +298,7 @@ static int run_complete_job(struct kcopyd_job *job)
		static void complete_io(unsigned long error, void *context)
		{
		struct kcopyd_job job = (struct kcopyd_job ) context;
		struct dm_kcopyd_client *kc = job->kc;

		if (error) {
		if (job->rw == WRITE)
		@@ -317,22 +306,22 @@ static void complete_io(unsigned long error, void *context)
		else
		job->read_err = 1;

		if (!test_bit(KCOPYD_IGNORE_ERROR, &job->flags)) {
		push(&_complete_jobs, job);
		wake();
		if (!test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) {
		push(&kc->complete_jobs, job);
		wake(kc);
		return;
		}
		}

		if (job->rw == WRITE)
		push(&_complete_jobs, job);
		push(&kc->complete_jobs, job);

		else {
		job->rw = WRITE;
		push(&_io_jobs, job);
		push(&kc->io_jobs, job);
		}

		wake();
		wake(kc);
		}

		/*
		@@ -343,7 +332,7 @@ static int run_io_job(struct kcopyd_job *job)
		{
		int r;
		struct dm_io_request io_req = {
		.bi_rw = job->rw,
		.bi_rw = job->rw \| (1 << BIO_RW_SYNC),
		.mem.type = DM_IO_PAGE_LIST,
		.mem.ptr.pl = job->pages,
		.mem.offset = job->offset,
		@@ -369,7 +358,7 @@ static int run_pages_job(struct kcopyd_job *job)
		r = kcopyd_get_pages(job->kc, job->nr_pages, &job->pages);
		if (!r) {
		/* this job is ready for io */
		push(&_io_jobs, job);
		push(&job->kc->io_jobs, job);
		return 0;
		}

		@@ -384,12 +373,13 @@ static int run_pages_job(struct kcopyd_job *job)
		* Run through a list for as long as possible. Returns the count
		* of successful jobs.
		*/
		static int process_jobs(struct list_head jobs, int (fn) (struct kcopyd_job *))
		static int process_jobs(struct list_head jobs, struct dm_kcopyd_client kc,
		int (fn) (struct kcopyd_job ))
		{
		struct kcopyd_job *job;
		int r, count = 0;

		while ((job = pop(jobs))) {
		while ((job = pop(jobs, kc))) {

		r = fn(job);

		@@ -399,7 +389,7 @@ static int process_jobs(struct list_head jobs, int (fn) (struct kcopyd_job *))
		job->write_err = (unsigned long) -1L;
		else
		job->read_err = 1;
		push(&_complete_jobs, job);
		push(&kc->complete_jobs, job);
		break;
		}

		@@ -421,8 +411,11 @@ static int process_jobs(struct list_head jobs, int (fn) (struct kcopyd_job *))
		/*
		* kcopyd does this every time it's woken up.
		*/
		static void do_work(struct work_struct *ignored)
		static void do_work(struct work_struct *work)
		{
		struct dm_kcopyd_client *kc = container_of(work,
		struct dm_kcopyd_client, kcopyd_work);

		/*
		* The order that these are called is very important.
		* complete jobs can free some pages for pages jobs.
		@@ -430,9 +423,9 @@ static void do_work(struct work_struct *ignored)
		* list. io jobs call wake when they complete and it all
		* starts again.
		*/
		process_jobs(&_complete_jobs, run_complete_job);
		process_jobs(&_pages_jobs, run_pages_job);
		process_jobs(&_io_jobs, run_io_job);
		process_jobs(&kc->complete_jobs, kc, run_complete_job);
		process_jobs(&kc->pages_jobs, kc, run_pages_job);
		process_jobs(&kc->io_jobs, kc, run_io_job);
		}

		/*
		@@ -442,9 +435,10 @@ static void do_work(struct work_struct *ignored)
		*/
		static void dispatch_job(struct kcopyd_job *job)
		{
		atomic_inc(&job->kc->nr_jobs);
		push(&_pages_jobs, job);
		wake();
		struct dm_kcopyd_client *kc = job->kc;
		atomic_inc(&kc->nr_jobs);
		push(&kc->pages_jobs, job);
		wake(kc);
		}

		#define SUB_JOB_SIZE 128
		@@ -469,7 +463,7 @@ static void segment_complete(int read_err, unsigned long write_err,
		* Only dispatch more work if there hasn't been an error.
		*/
		if ((!job->read_err && !job->write_err) \|\|
		test_bit(KCOPYD_IGNORE_ERROR, &job->flags)) {
		test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) {
		/* get the next chunk of work */
		progress = job->progress;
		count = job->source.count - progress;
		@@ -484,7 +478,8 @@ static void segment_complete(int read_err, unsigned long write_err,

		if (count) {
		int i;
		struct kcopyd_job *sub_job = mempool_alloc(_job_pool, GFP_NOIO);
		struct kcopyd_job *sub_job = mempool_alloc(job->kc->job_pool,
		GFP_NOIO);

		sub_job = job;
		sub_job->source.sector += progress;
		@@ -508,7 +503,7 @@ static void segment_complete(int read_err, unsigned long write_err,
		* after we've completed.
		*/
		job->fn(read_err, write_err, job->context);
		mempool_free(job, _job_pool);
		mempool_free(job, job->kc->job_pool);
		}
		}

		@@ -526,16 +521,16 @@ static void split_job(struct kcopyd_job *job)
		segment_complete(0, 0u, job);
		}

		int kcopyd_copy(struct kcopyd_client kc, struct io_region from,
		unsigned int num_dests, struct io_region *dests,
		unsigned int flags, kcopyd_notify_fn fn, void *context)
		int dm_kcopyd_copy(struct dm_kcopyd_client kc, struct dm_io_region from,
		unsigned int num_dests, struct dm_io_region *dests,
		unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
		{
		struct kcopyd_job *job;

		/*
		* Allocate a new job.
		*/
		job = mempool_alloc(_job_pool, GFP_NOIO);
		job = mempool_alloc(kc->job_pool, GFP_NOIO);

		/*
		* set up for the read.
		@@ -569,6 +564,7 @@ int kcopyd_copy(struct kcopyd_client kc, struct io_region from,

		return 0;
		}
		EXPORT_SYMBOL(dm_kcopyd_copy);

		/*
		* Cancels a kcopyd job, eg. someone might be deactivating a
		@@ -583,126 +579,76 @@ int kcopyd_cancel(struct kcopyd_job *job, int block)
		#endif /* 0 */

		/*-----------------------------------------------------------------
		* Unit setup
		* Client setup
		---------------------------------------------------------------/
		static DEFINE_MUTEX(_client_lock);
		static LIST_HEAD(_clients);

		static void client_add(struct kcopyd_client *kc)
		int dm_kcopyd_client_create(unsigned int nr_pages,
		struct dm_kcopyd_client **result)
		{
		mutex_lock(&_client_lock);
		list_add(&kc->list, &_clients);
		mutex_unlock(&_client_lock);
		}
		int r = -ENOMEM;
		struct dm_kcopyd_client *kc;

		static void client_del(struct kcopyd_client *kc)
		{
		mutex_lock(&_client_lock);
		list_del(&kc->list);
		mutex_unlock(&_client_lock);
		}

		static DEFINE_MUTEX(kcopyd_init_lock);
		static int kcopyd_clients = 0;

		static int kcopyd_init(void)
		{
		int r;

		mutex_lock(&kcopyd_init_lock);

		if (kcopyd_clients) {
		/* Already initialized. */
		kcopyd_clients++;
		mutex_unlock(&kcopyd_init_lock);
		return 0;
		}

		r = jobs_init();
		if (r) {
		mutex_unlock(&kcopyd_init_lock);
		return r;
		}

		_kcopyd_wq = create_singlethread_workqueue("kcopyd");
		if (!_kcopyd_wq) {
		jobs_exit();
		mutex_unlock(&kcopyd_init_lock);
		kc = kmalloc(sizeof(*kc), GFP_KERNEL);
		if (!kc)
		return -ENOMEM;
		}

		kcopyd_clients++;
		INIT_WORK(&_kcopyd_work, do_work);
		mutex_unlock(&kcopyd_init_lock);
		return 0;
		}

		static void kcopyd_exit(void)
		{
		mutex_lock(&kcopyd_init_lock);
		kcopyd_clients--;
		if (!kcopyd_clients) {
		jobs_exit();
		destroy_workqueue(_kcopyd_wq);
		_kcopyd_wq = NULL;
		}
		mutex_unlock(&kcopyd_init_lock);
		}

		int kcopyd_client_create(unsigned int nr_pages, struct kcopyd_client **result)
		{
		int r = 0;
		struct kcopyd_client *kc;
		spin_lock_init(&kc->lock);
		spin_lock_init(&kc->job_lock);
		INIT_LIST_HEAD(&kc->complete_jobs);
		INIT_LIST_HEAD(&kc->io_jobs);
		INIT_LIST_HEAD(&kc->pages_jobs);

		r = kcopyd_init();
		if (r)
		return r;
		kc->job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
		if (!kc->job_pool)
		goto bad_slab;

		kc = kmalloc(sizeof(*kc), GFP_KERNEL);
		if (!kc) {
		kcopyd_exit();
		return -ENOMEM;
		}
		INIT_WORK(&kc->kcopyd_work, do_work);
		kc->kcopyd_wq = create_singlethread_workqueue("kcopyd");
		if (!kc->kcopyd_wq)
		goto bad_workqueue;

		spin_lock_init(&kc->lock);
		kc->pages = NULL;
		kc->nr_pages = kc->nr_free_pages = 0;
		r = client_alloc_pages(kc, nr_pages);
		if (r) {
		kfree(kc);
		kcopyd_exit();
		return r;
		}
		if (r)
		goto bad_client_pages;

		kc->io_client = dm_io_client_create(nr_pages);
		if (IS_ERR(kc->io_client)) {
		r = PTR_ERR(kc->io_client);
		client_free_pages(kc);
		kfree(kc);
		kcopyd_exit();
		return r;
		goto bad_io_client;
		}

		init_waitqueue_head(&kc->destroyq);
		atomic_set(&kc->nr_jobs, 0);

		client_add(kc);
		*result = kc;
		return 0;

		bad_io_client:
		client_free_pages(kc);
		bad_client_pages:
		destroy_workqueue(kc->kcopyd_wq);
		bad_workqueue:
		mempool_destroy(kc->job_pool);
		bad_slab:
		kfree(kc);

		return r;
		}
		EXPORT_SYMBOL(dm_kcopyd_client_create);

		void kcopyd_client_destroy(struct kcopyd_client *kc)
		void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc)
		{
		/* Wait for completion of all jobs submitted by this client. */
		wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));

		BUG_ON(!list_empty(&kc->complete_jobs));
		BUG_ON(!list_empty(&kc->io_jobs));
		BUG_ON(!list_empty(&kc->pages_jobs));
		destroy_workqueue(kc->kcopyd_wq);
		dm_io_client_destroy(kc->io_client);
		client_free_pages(kc);
		client_del(kc);
		mempool_destroy(kc->job_pool);
		kfree(kc);
		kcopyd_exit();
		}

		EXPORT_SYMBOL(kcopyd_client_create);
		EXPORT_SYMBOL(kcopyd_client_destroy);
		EXPORT_SYMBOL(kcopyd_copy);
		EXPORT_SYMBOL(dm_kcopyd_client_destroy);

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