From: Milan Broz <mbroz@redhat.com>
Subject: [RHEL 5.1 PATCH] dm: failures when creating many snapshots (new dm-io  interface)
Date: Tue, 24 Apr 2007 15:57:14 +0200
Bugzilla: 211516 211525
Message-Id: <462E0CBA.8080602@redhat.com>
Changelog: [dm] failures when creating many snapshots


RHEL5.1 device mapper: failures when creating many snapshots (new dm-io interface)

Resolves:
 rhbz#211516 - memory issues cause "failures" when creating many snapshots
 rhbz#211525 - mempool_resize BUG() during multiple snapshot removals


Current implementation of dm-io uses one common mempool for all clients.
This causes many problems when kernel cannot alocate or resize such
big amount of memory.

These patches backport a new API to dm-io that uses a private mempool and
bio_set for each client.
All dm internal modules are patched to use new dm-io interface
(kcopyd, exception store, raid1).
New interface is also required for dm-raid45 target.

Patch retaining full compatibility with old interface, no changes are
needed for external modules.

kABI impact:
 these exported functions are added (new dm-io interface):
	dm_io_client_create
	dm_io_client_resize
	dm_io_client_destroy
	dm_io

No changes to existing kABI, just these existing functions
use pointer to changed internal struct (hidden by ifdef magic)
	kcopyd_client_create
	kcopyd_client_destroy


Patches are upstream in -mm tree (planned for 2.6.22).

Testing:
 - All targets using dm-io tested with new patch including  
 pvmove/mirror operation + integrity test after move,
 snapshot creation an removing.
 - There are test cases on bugzillas to reproduce problems
 with multiple snapshots.


---
 drivers/md/dm-exception-store.c |   49 +++++----
 drivers/md/dm-io.c              |  204 +++++++++++++++++++++++++++++++++++-----
 drivers/md/dm-io.h              |   53 ++++++++++
 drivers/md/dm-log.c             |   31 ++++--
 drivers/md/dm-raid1.c           |   43 ++++++--
 drivers/md/kcopyd.c             |   28 +++--
 6 files changed, 334 insertions(+), 74 deletions(-)

Index: linux-2.6.18/drivers/md/dm-io.c
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-io.c	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-io.c	2007-04-23 14:49:27.000000000 +0200
@@ -14,11 +14,17 @@
 
 static struct bio_set *_bios;
 
+struct dm_io_client {
+	mempool_t *pool;
+	struct bio_set *bios;
+};
+
 /* FIXME: can we shrink this ? */
 struct io {
 	unsigned long error;
 	atomic_t count;
 	struct task_struct *sleeper;
+	struct dm_io_client *client;
 	io_notify_fn callback;
 	void *context;
 };
@@ -32,6 +38,19 @@ struct io {
 static unsigned _num_ios;
 static mempool_t *_io_pool;
 
+/*
+ * Temporary functions to allow old and new interfaces to co-exist.
+ */
+static struct bio_set *bios(struct dm_io_client *client)
+{
+	return client ? client->bios : _bios;
+}
+
+static mempool_t *io_pool(struct dm_io_client *client)
+{
+	return client ? client->pool : _io_pool;
+}
+
 static unsigned int pages_to_ios(unsigned int pages)
 {
 	return 4 * pages;	/* too many ? */
@@ -84,6 +103,51 @@ void dm_io_put(unsigned int num_pages)
 	resize_pool(_num_ios - pages_to_ios(num_pages));
 }
 
+/*
+ * Create a client with mempool and bioset.
+ */
+struct dm_io_client *dm_io_client_create(unsigned num_pages)
+{
+	unsigned ios = pages_to_ios(num_pages);
+	struct dm_io_client *client;
+
+	client = kmalloc(sizeof(*client), GFP_KERNEL);
+	if (!client)
+		return ERR_PTR(-ENOMEM);
+
+	client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
+	if (!client->pool)
+		goto bad;
+
+	client->bios = bioset_create(16, 16, 4);
+	if (!client->bios)
+		goto bad;
+
+	return client;
+
+   bad:
+	if (client->pool)
+		mempool_destroy(client->pool);
+	kfree(client);
+	return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL(dm_io_client_create);
+
+int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
+{
+	return mempool_resize(client->pool, pages_to_ios(num_pages),
+			      GFP_KERNEL);
+}
+EXPORT_SYMBOL(dm_io_client_resize);
+
+void dm_io_client_destroy(struct dm_io_client *client)
+{
+	mempool_destroy(client->pool);
+	bioset_free(client->bios);
+	kfree(client);
+}
+EXPORT_SYMBOL(dm_io_client_destroy);
+
 /*-----------------------------------------------------------------
  * We need to keep track of which region a bio is doing io for.
  * In order to save a memory allocation we store this the last
@@ -92,12 +156,12 @@ void dm_io_put(unsigned int num_pages)
  *---------------------------------------------------------------*/
 static inline void bio_set_region(struct bio *bio, unsigned region)
 {
-	bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len = region;
+	bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
 }
 
 static inline unsigned bio_get_region(struct bio *bio)
 {
-	return bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len;
+	return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
 }
 
 /*-----------------------------------------------------------------
@@ -118,7 +182,7 @@ static void dec_count(struct io *io, uns
 			io_notify_fn fn = io->callback;
 			void *context = io->context;
 
-			mempool_free(io, _io_pool);
+			mempool_free(io, io_pool(io->client));
 			fn(r, context);
 		}
 	}
@@ -126,7 +190,8 @@ static void dec_count(struct io *io, uns
 
 static int endio(struct bio *bio, unsigned int done, int error)
 {
-	struct io *io = (struct io *) bio->bi_private;
+	struct io *io;
+	unsigned region;
 
 	/* keep going until we've finished */
 	if (bio->bi_size)
@@ -135,9 +200,17 @@ static int endio(struct bio *bio, unsign
 	if (error && bio_data_dir(bio) == READ)
 		zero_fill_bio(bio);
 
-	dec_count(io, bio_get_region(bio), error);
+	/*
+	 * The bio destructor in bio_put() may use the io object.
+	 */
+	io = bio->bi_private;
+	region = bio_get_region(bio);
+
+	bio->bi_max_vecs++;
 	bio_put(bio);
 
+	dec_count(io, region, error);
+
 	return 0;
 }
 
@@ -208,6 +281,9 @@ static void bvec_dp_init(struct dpages *
 	dp->context_ptr = bvec;
 }
 
+/*
+ * Functions for getting the pages from a VMA.
+ */
 static void vm_get_page(struct dpages *dp,
 		 struct page **p, unsigned long *len, unsigned *offset)
 {
@@ -232,7 +308,34 @@ static void vm_dp_init(struct dpages *dp
 
 static void dm_bio_destructor(struct bio *bio)
 {
-	bio_free(bio, _bios);
+	struct io *io = bio->bi_private;
+
+	bio_free(bio, bios(io->client));
+}
+
+/*
+ * Functions for getting the pages from kernel memory.
+ */
+static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
+			unsigned *offset)
+{
+	*p = virt_to_page(dp->context_ptr);
+	*offset = dp->context_u;
+	*len = PAGE_SIZE - dp->context_u;
+}
+
+static void km_next_page(struct dpages *dp)
+{
+	dp->context_ptr += PAGE_SIZE - dp->context_u;
+	dp->context_u = 0;
+}
+
+static void km_dp_init(struct dpages *dp, void *data)
+{
+	dp->get_page = km_get_page;
+	dp->next_page = km_next_page;
+	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
+	dp->context_ptr = data;
 }
 
 /*-----------------------------------------------------------------
@@ -250,16 +353,18 @@ static void do_region(int rw, unsigned i
 
 	while (remaining) {
 		/*
-		 * Allocate a suitably sized bio, we add an extra
-		 * bvec for bio_get/set_region().
+		 * Allocate a suitably sized-bio: we add an extra
+		 * bvec for bio_get/set_region() and decrement bi_max_vecs
+		 * to hide it from bio_add_page().
 		 */
-		num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 2;
-		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
+		num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
+		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
 		bio->bi_sector = where->sector + (where->count - remaining);
 		bio->bi_bdev = where->bdev;
 		bio->bi_end_io = endio;
 		bio->bi_private = io;
 		bio->bi_destructor = dm_bio_destructor;
+		bio->bi_max_vecs--;
 		bio_set_region(bio, region);
 
 		/*
@@ -308,8 +413,9 @@ static void dispatch_io(int rw, unsigned
 	dec_count(io, 0, 0);
 }
 
-static int sync_io(unsigned int num_regions, struct io_region *where,
-	    int rw, struct dpages *dp, unsigned long *error_bits)
+static int sync_io(struct dm_io_client *client, unsigned int num_regions,
+		   struct io_region *where, int rw, struct dpages *dp,
+		   unsigned long *error_bits)
 {
 	struct io io;
 
@@ -321,6 +427,7 @@ static int sync_io(unsigned int num_regi
 	io.error = 0;
 	atomic_set(&io.count, 1); /* see dispatch_io() */
 	io.sleeper = current;
+	io.client = client;
 
 	dispatch_io(rw, num_regions, where, dp, &io, 1);
 
@@ -337,12 +444,15 @@ static int sync_io(unsigned int num_regi
 	if (atomic_read(&io.count))
 		return -EINTR;
 
-	*error_bits = io.error;
+	if (error_bits)
+		*error_bits = io.error;
+
 	return io.error ? -EIO : 0;
 }
 
-static int async_io(unsigned int num_regions, struct io_region *where, int rw,
-	     struct dpages *dp, io_notify_fn fn, void *context)
+static int async_io(struct dm_io_client *client, unsigned int num_regions,
+		    struct io_region *where, int rw, struct dpages *dp,
+		    io_notify_fn fn, void *context)
 {
 	struct io *io;
 
@@ -352,10 +462,11 @@ static int async_io(unsigned int num_reg
 		return -EIO;
 	}
 
-	io = mempool_alloc(_io_pool, GFP_NOIO);
+	io = mempool_alloc(io_pool(client), GFP_NOIO);
 	io->error = 0;
 	atomic_set(&io->count, 1); /* see dispatch_io() */
 	io->sleeper = NULL;
+	io->client = client;
 	io->callback = fn;
 	io->context = context;
 
@@ -369,7 +480,7 @@ int dm_io_sync(unsigned int num_regions,
 {
 	struct dpages dp;
 	list_dp_init(&dp, pl, offset);
-	return sync_io(num_regions, where, rw, &dp, error_bits);
+	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
@@ -377,7 +488,7 @@ int dm_io_sync_bvec(unsigned int num_reg
 {
 	struct dpages dp;
 	bvec_dp_init(&dp, bvec);
-	return sync_io(num_regions, where, rw, &dp, error_bits);
+	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
@@ -385,7 +496,7 @@ int dm_io_sync_vm(unsigned int num_regio
 {
 	struct dpages dp;
 	vm_dp_init(&dp, data);
-	return sync_io(num_regions, where, rw, &dp, error_bits);
+	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
@@ -394,7 +505,7 @@ int dm_io_async(unsigned int num_regions
 {
 	struct dpages dp;
 	list_dp_init(&dp, pl, offset);
-	return async_io(num_regions, where, rw, &dp, fn, context);
+	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 }
 
 int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
@@ -402,7 +513,7 @@ int dm_io_async_bvec(unsigned int num_re
 {
 	struct dpages dp;
 	bvec_dp_init(&dp, bvec);
-	return async_io(num_regions, where, rw, &dp, fn, context);
+	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 }
 
 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
@@ -410,8 +521,57 @@ int dm_io_async_vm(unsigned int num_regi
 {
 	struct dpages dp;
 	vm_dp_init(&dp, data);
-	return async_io(num_regions, where, rw, &dp, fn, context);
+	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
+}
+
+static int dp_init(struct dm_io_request *io_req, struct dpages *dp)
+{
+	/* Set up dpages based on memory type */
+	switch (io_req->mem.type) {
+	case DM_IO_PAGE_LIST:
+		list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
+		break;
+
+	case DM_IO_BVEC:
+		bvec_dp_init(dp, io_req->mem.ptr.bvec);
+		break;
+
+	case DM_IO_VMA:
+		vm_dp_init(dp, io_req->mem.ptr.vma);
+		break;
+
+	case DM_IO_KMEM:
+		km_dp_init(dp, io_req->mem.ptr.addr);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * New collapsed (a)synchronous interface
+ */
+int dm_io(struct dm_io_request *io_req, unsigned num_regions,
+	  struct io_region *where, unsigned long *sync_error_bits)
+{
+	int r;
+	struct dpages dp;
+
+	r = dp_init(io_req, &dp);
+	if (r)
+		return r;
+
+	if (!io_req->notify.fn)
+		return sync_io(io_req->client, num_regions, where,
+			       io_req->bi_rw, &dp, sync_error_bits);
+
+	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
+			&dp, io_req->notify.fn, io_req->notify.context);
 }
+EXPORT_SYMBOL(dm_io);
 
 EXPORT_SYMBOL(dm_io_get);
 EXPORT_SYMBOL(dm_io_put);
Index: linux-2.6.18/drivers/md/dm-io.h
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-io.h	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-io.h	2007-04-23 15:17:20.000000000 +0200
@@ -27,6 +27,41 @@ struct page_list {
  */
 typedef void (*io_notify_fn)(unsigned long error, void *context);
 
+enum dm_io_mem_type {
+	DM_IO_PAGE_LIST,/* Page list */
+	DM_IO_BVEC,	/* Bio vector */
+	DM_IO_VMA,	/* Virtual memory area */
+	DM_IO_KMEM,	/* Kernel memory */
+};
+
+struct dm_io_memory {
+	enum dm_io_mem_type type;
+
+	union {
+		struct page_list *pl;
+		struct bio_vec *bvec;
+		void *vma;
+		void *addr;
+	} ptr;
+
+	unsigned offset;
+};
+
+struct dm_io_notify {
+	io_notify_fn fn;	/* Callback for asynchronous requests */
+	void *context;		/* Passed to callback */
+};
+
+/*
+ * IO request structure
+ */
+struct dm_io_client;
+struct dm_io_request {
+	int bi_rw;			/* READ|WRITE - not READA */
+	struct dm_io_memory mem;	/* Memory to use for io */
+	struct dm_io_notify notify;	/* Synchronous if notify.fn is NULL */
+	struct dm_io_client *client;	/* Client memory handler */
+};
 
 /*
  * Before anyone uses the IO interface they should call
@@ -39,6 +74,16 @@ int dm_io_get(unsigned int num_pages);
 void dm_io_put(unsigned int num_pages);
 
 /*
+ * For async io calls, users can alternatively use the dm_io() function below
+ * and dm_io_client_create() to create private mempools for the client.
+ *
+ * Create/destroy may block.
+ */
+struct dm_io_client *dm_io_client_create(unsigned num_pages);
+int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client);
+void dm_io_client_destroy(struct dm_io_client *client);
+
+/*
  * Synchronous IO.
  *
  * Please ensure that the rw flag in the next two functions is
@@ -71,4 +116,12 @@ int dm_io_async_bvec(unsigned int num_re
 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
 		   void *data, io_notify_fn fn, void *context);
 
+/*
+ * IO interface using private per-client pools.
+ * Each bit in the optional 'sync_error_bits' bitset indicates whether an
+ * error occurred doing io to the corresponding region.
+ */
+int dm_io(struct dm_io_request *io_req, unsigned num_regions,
+	  struct io_region *region, unsigned long *sync_error_bits);
+
 #endif
Index: linux-2.6.18/drivers/md/kcopyd.c
===================================================================
--- linux-2.6.18.orig/drivers/md/kcopyd.c	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/kcopyd.c	2007-04-23 15:09:03.000000000 +0200
@@ -47,6 +47,9 @@ struct kcopyd_client {
 
 	wait_queue_head_t destroyq;
 	atomic_t nr_jobs;
+#ifndef __GENKSYMS__
+	struct dm_io_client *io_client;
+#endif
 };
 
 static struct page_list *alloc_pl(void)
@@ -342,16 +345,20 @@ static void complete_io(unsigned long er
 static int run_io_job(struct kcopyd_job *job)
 {
 	int r;
+	struct dm_io_request io_req = {
+		.bi_rw = job->rw,
+		.mem.type = DM_IO_PAGE_LIST,
+		.mem.ptr.pl = job->pages,
+		.mem.offset = job->offset,
+		.notify.fn = complete_io,
+		.notify.context = job,
+		.client = job->kc->io_client,
+	};
 
 	if (job->rw == READ)
-		r = dm_io_async(1, &job->source, job->rw,
-				job->pages,
-				job->offset, complete_io, job);
-
+		r = dm_io(&io_req, 1, &job->source, NULL);
 	else
-		r = dm_io_async(job->num_dests, job->dests, job->rw,
-				job->pages,
-				job->offset, complete_io, job);
+		r = dm_io(&io_req, job->num_dests, job->dests, NULL);
 
 	return r;
 }
@@ -670,8 +677,9 @@ int kcopyd_client_create(unsigned int nr
 		return r;
 	}
 
-	r = dm_io_get(nr_pages);
-	if (r) {
+	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();
@@ -691,7 +699,7 @@ void kcopyd_client_destroy(struct kcopyd
 	/* Wait for completion of all jobs submitted by this client. */
 	wait_event(kc->destroyq, !atomic_read(&kc->nr_jobs));
 
-	dm_io_put(kc->nr_pages);
+	dm_io_client_destroy(kc->io_client);
 	client_free_pages(kc);
 	client_del(kc);
 	kfree(kc);
Index: linux-2.6.18/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-exception-store.c	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-exception-store.c	2007-04-23 14:49:27.000000000 +0200
@@ -123,6 +123,7 @@ struct pstore {
 	atomic_t pending_count;
 	uint32_t callback_count;
 	struct commit_callback *callbacks;
+	struct dm_io_client *io_client;
 };
 
 static inline unsigned int sectors_to_pages(unsigned int sectors)
@@ -159,14 +160,20 @@ static void free_area(struct pstore *ps)
  */
 static int chunk_io(struct pstore *ps, uint32_t chunk, int rw)
 {
-	struct io_region where;
-	unsigned long bits;
+	struct io_region where = {
+		.bdev = ps->snap->cow->bdev,
+		.sector = ps->snap->chunk_size * chunk,
+		.count = ps->snap->chunk_size,
+	};
+	struct dm_io_request io_req = {
+		.bi_rw = rw,
+		.mem.type = DM_IO_VMA,
+		.mem.ptr.vma = ps->area,
+		.client = ps->io_client,
+		.notify.fn = NULL,
+	};
 
-	where.bdev = ps->snap->cow->bdev;
-	where.sector = ps->snap->chunk_size * chunk;
-	where.count = ps->snap->chunk_size;
-
-	return dm_io_sync_vm(1, &where, rw, ps->area, &bits);
+	return dm_io(&io_req, 1, &where, NULL);
 }
 
 /*
@@ -213,17 +220,18 @@ static int read_header(struct pstore *ps
 		chunk_size_supplied = 0;
 	}
 
-	r = dm_io_get(sectors_to_pages(ps->snap->chunk_size));
-	if (r)
-		return r;
+	ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap->
+							     chunk_size));
+	if (IS_ERR(ps->io_client))
+		return PTR_ERR(ps->io_client);
 
 	r = alloc_area(ps);
 	if (r)
-		goto bad1;
+		return r;
 
 	r = chunk_io(ps, 0, READ);
 	if (r)
-		goto bad2;
+		goto bad;
 
 	dh = (struct disk_header *) ps->area;
 
@@ -235,7 +243,7 @@ static int read_header(struct pstore *ps
 	if (le32_to_cpu(dh->magic) != SNAP_MAGIC) {
 		DMWARN("Invalid or corrupt snapshot");
 		r = -ENXIO;
-		goto bad2;
+		goto bad;
 	}
 
 	*new_snapshot = 0;
@@ -252,27 +260,22 @@ static int read_header(struct pstore *ps
 	       (unsigned long long)ps->snap->chunk_size);
 
 	/* We had a bogus chunk_size. Fix stuff up. */
-	dm_io_put(sectors_to_pages(ps->snap->chunk_size));
 	free_area(ps);
 
 	ps->snap->chunk_size = chunk_size;
 	ps->snap->chunk_mask = chunk_size - 1;
 	ps->snap->chunk_shift = ffs(chunk_size) - 1;
 
-	r = dm_io_get(sectors_to_pages(chunk_size));
+	r = dm_io_client_resize(sectors_to_pages(ps->snap->chunk_size),
+				ps->io_client);
 	if (r)
 		return r;
 
 	r = alloc_area(ps);
-	if (r)
-		goto bad1;
-
-	return 0;
+	return r;
 
-bad2:
+bad:
 	free_area(ps);
-bad1:
-	dm_io_put(sectors_to_pages(ps->snap->chunk_size));
 	return r;
 }
 
@@ -405,7 +408,7 @@ static void persistent_destroy(struct ex
 {
 	struct pstore *ps = get_info(store);
 
-	dm_io_put(sectors_to_pages(ps->snap->chunk_size));
+	dm_io_client_destroy(ps->io_client);
 	vfree(ps->callbacks);
 	free_area(ps);
 	kfree(ps);
Index: linux-2.6.18/drivers/md/dm-log.c
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-log.c	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-log.c	2007-04-23 14:49:27.000000000 +0200
@@ -152,6 +152,8 @@ struct log_c {
 
 	int failure_response;
 
+	struct dm_io_request io_req;
+
 	/*
 	 * Disk log fields
 	 */
@@ -203,13 +205,20 @@ static void header_from_disk(struct log_
 	core->nr_regions = le64_to_cpu(disk->nr_regions);
 }
 
+static int rw_header(struct log_c *lc, int rw)
+{
+	lc->io_req.bi_rw = rw;
+	lc->io_req.mem.ptr.vma = lc->disk_header;
+	lc->io_req.notify.fn = NULL;
+
+	return dm_io(&lc->io_req, 1, &lc->header_location, NULL);
+}
+
 static int read_header(struct log_c *log)
 {
 	int r;
-	unsigned long ebits;
 
-	r = dm_io_sync_vm(1, &log->header_location, READ,
-			  log->disk_header, &ebits);
+	r = rw_header(log, READ);
 	if (r)
 		return r;
 
@@ -237,11 +246,8 @@ static int read_header(struct log_c *log
 
 static inline int write_header(struct log_c *log)
 {
-	unsigned long ebits;
-
 	header_to_disk(&log->header, log->disk_header);
-	return dm_io_sync_vm(1, &log->header_location, WRITE,
-			     log->disk_header, &ebits);
+	return rw_header(log, WRITE);
 }
 
 /*----------------------------------------------------------------
@@ -262,6 +268,7 @@ static int create_log_context(struct dir
 	uint32_t region_size;
 	unsigned int region_count;
 	size_t bitset_size, buf_size;
+	int r;
 
 	if (argc < 1 || argc > 3) {
 		DMWARN("wrong number of arguments to mirror log");
@@ -334,6 +341,15 @@ static int create_log_context(struct dir
 		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
 				       bitset_size, ti->limits.hardsect_size);
 		lc->header_location.count = buf_size >> SECTOR_SHIFT;
+		lc->io_req.mem.type = DM_IO_VMA;
+		lc->io_req.client = dm_io_client_create(dm_div_up(buf_size,
+								   PAGE_SIZE));
+		if (IS_ERR(lc->io_req.client)) {
+			r = PTR_ERR(lc->io_req.client);
+			DMWARN("couldn't allocate disk io client");
+			kfree(lc);
+			return -ENOMEM;
+		}
 
 		lc->disk_header = vmalloc(buf_size);
 		if (!lc->disk_header) {
@@ -435,6 +451,7 @@ static void disk_dtr(struct dirty_log *l
 
 	dm_put_device(lc->ti, lc->log_dev);
 	vfree(lc->disk_header);
+	dm_io_client_destroy(lc->io_req.client);
 	destroy_log_context(lc);
 }
 
Index: linux-2.6.18/drivers/md/dm-raid1.c
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-raid1.c	2007-04-23 14:46:44.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-raid1.c	2007-04-23 14:49:27.000000000 +0200
@@ -22,6 +22,7 @@
 #include <linux/workqueue.h>
 
 #define DM_MSG_PREFIX "raid1"
+#define DM_IO_PAGES 64
 
 DECLARE_WAIT_QUEUE_HEAD(recovery_stopped_event);
 
@@ -129,6 +130,8 @@ struct mirror_set {
 	struct bio_list writes;
 	struct bio_list failures;
 
+	struct dm_io_client *io_client;
+
 	/* recovery */
 	region_t nr_regions;
 	int in_sync;
@@ -937,12 +940,18 @@ static void read_callback(unsigned long 
 static void read_async_bio(struct mirror *m, struct bio *bio)
 {
 	struct io_region io;
+	struct dm_io_request io_req = {
+		.bi_rw = READ,
+		.mem.type = DM_IO_BVEC,
+		.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
+		.notify.fn = read_callback,
+		.notify.context = bio,
+		.client = m->ms->io_client,
+	};
 
 	map_region(&io, m, bio);
 	bio_set_m(bio, m);
-	dm_io_async_bvec(1, &io, READ,
-			 bio->bi_io_vec + bio->bi_idx,
-			 read_callback, bio);
+	(void) dm_io(&io_req, m->ms->nr_mirrors, &io, NULL);
 }
 
 static void do_reads(struct mirror_set *ms, struct bio_list *reads)
@@ -1108,6 +1117,14 @@ static void do_write(struct mirror_set *
 	unsigned int i;
 	struct io_region io[ms->nr_mirrors], *dest = io;
 	struct mirror *m;
+	struct dm_io_request io_req = {
+		.bi_rw = WRITE,
+		.mem.type = DM_IO_BVEC,
+		.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
+		.notify.fn = NULL,
+		.notify.context = bio,
+		.client = ms->io_client,
+	};
 
 	if (log_failure && dm_mirror_error_on_log_failure) {
 		bio_endio(bio, bio->bi_size, -EIO);
@@ -1123,14 +1140,9 @@ static void do_write(struct mirror_set *
 	 * to the mirror set in write_callback().
 	 */
 	bio_set_m(bio, ms->default_mirror);
-	if (log_failure)
-		dm_io_async_bvec(ms->nr_mirrors, io, WRITE,
-				 bio->bi_io_vec + bio->bi_idx,
-				 write_callback_bad_log, bio);
-	else
-		dm_io_async_bvec(ms->nr_mirrors, io, WRITE,
-				 bio->bi_io_vec + bio->bi_idx,
-				 write_callback_good_log, bio);
+	io_req.notify.fn = log_failure ? write_callback_bad_log :
+					 write_callback_good_log;
+	(void) dm_io(&io_req, ms->nr_mirrors, io, NULL);
 }
 
 static void do_writes(struct mirror_set *ms, struct bio_list *writes)
@@ -1294,6 +1306,13 @@ static struct mirror_set *alloc_context(
 	ms->read_mirror = &ms->mirror[DEFAULT_MIRROR];
 	ms->default_mirror = &ms->mirror[DEFAULT_MIRROR];
 
+	ms->io_client = dm_io_client_create(DM_IO_PAGES);
+	if (IS_ERR(ms->io_client)) {
+		ti->error = "Error creating dm_io client";
+		kfree(ms);
+ 		return NULL;
+	}
+
 	if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
 		ti->error = "Error creating dirty region hash";
 		kfree(ms);
@@ -1313,6 +1332,7 @@ static void free_context(struct mirror_s
 	while (m--)
 		dm_put_device(ti, ms->mirror[m].dev);
 
+	dm_io_client_destroy(ms->io_client);
 	rh_exit(&ms->rh);
 	kfree(ms);
 }
@@ -1398,7 +1418,6 @@ static struct dirty_log *create_dirty_lo
  * log_type is "core" or "disk"
  * #log_params is between 1 and 3
  */
-#define DM_IO_PAGES 64
 static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	int r;