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Commit f26c5719 authored by Dan Williams's avatar Dan Williams
Browse files

dm: add dax_device and dax_operations support 



Allocate a dax_device to represent the capacity of a device-mapper
instance. Provide a ->direct_access() method via the new dax_operations
indirection that mirrors the functionality of the current direct_access
support via block_device_operations.  Once fs/dax.c has been converted
to use dax_operations the old dm_blk_direct_access() will be removed.

A new helper dm_dax_get_live_target() is introduced to separate some of
the dm-specifics from the direct_access implementation.

This enabling is only for the top-level dm representation to upper
layers. Converting target direct_access implementations is deferred to a
separate patch.

Cc: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent b0686260

drivers/md/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ config BLK_DEV_DM_BUILTIN 
config BLK_DEV_DM

	tristate "Device mapper support"

	select BLK_DEV_DM_BUILTIN

	select DAX

	---help---

	  Device-mapper is a low level volume manager.  It works by allowing

	  people to specify mappings for ranges of logical sectors.  Various

drivers/md/dm-core.h

+1 −0
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ struct mapped_device { 
	struct target_type *immutable_target_type;



	struct gendisk *disk;

	struct dax_device *dax_dev;

	char name[16];



	void *interface_ptr;

drivers/md/dm.c

+70 −14
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/blkpg.h>

#include <linux/bio.h>

#include <linux/mempool.h>

#include <linux/dax.h>

#include <linux/slab.h>

#include <linux/idr.h>

#include <linux/hdreg.h>
@@ -908,31 +909,68 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len) 
}

EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);



static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,

				 void **kaddr, pfn_t *pfn, long size)

static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,

		sector_t sector, int *srcu_idx)

{

	struct mapped_device *md = bdev->bd_disk->private_data;

	struct dm_table *map;

	struct dm_target *ti;

	int srcu_idx;

	long len, ret = -EIO;



	map = dm_get_live_table(md, &srcu_idx);

	map = dm_get_live_table(md, srcu_idx);

	if (!map)

		goto out;

		return NULL;



	ti = dm_table_find_target(map, sector);

	if (!dm_target_is_valid(ti))

		goto out;

		return NULL;



	len = max_io_len(sector, ti) << SECTOR_SHIFT;

	size = min(len, size);

	return ti;

}



static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,

		long nr_pages, void **kaddr, pfn_t *pfn)

{

	struct mapped_device *md = dax_get_private(dax_dev);

	sector_t sector = pgoff * PAGE_SECTORS;

	struct dm_target *ti;

	long len, ret = -EIO;

	int srcu_idx;



	ti = dm_dax_get_live_target(md, sector, &srcu_idx);



	if (ti->type->direct_access)

		ret = ti->type->direct_access(ti, sector, kaddr, pfn, size);

	if (!ti)

		goto out;

	if (!ti->type->direct_access)

		goto out;

	len = max_io_len(sector, ti) / PAGE_SECTORS;

	if (len < 1)

		goto out;

	nr_pages = min(len, nr_pages);

	if (ti->type->direct_access) {

		ret = ti->type->direct_access(ti, sector, kaddr, pfn,

				nr_pages * PAGE_SIZE);

		/*

		 * FIXME: convert ti->type->direct_access to return

		 * nr_pages directly.

		 */

		if (ret >= 0)

			ret /= PAGE_SIZE;

	}

 out:

	dm_put_live_table(md, srcu_idx);

	return min(ret, size);



	return ret;

}



static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,

		void **kaddr, pfn_t *pfn, long size)

{

	struct mapped_device *md = bdev->bd_disk->private_data;

	struct dax_device *dax_dev = md->dax_dev;

	long nr_pages = size / PAGE_SIZE;



	nr_pages = dm_dax_direct_access(dax_dev, sector / PAGE_SECTORS,

			nr_pages, kaddr, pfn);

	return nr_pages < 0 ? nr_pages : nr_pages * PAGE_SIZE;

}



/*
@@ -1437,6 +1475,7 @@ static int next_free_minor(int *minor) 
}



static const struct block_device_operations dm_blk_dops;

static const struct dax_operations dm_dax_ops;



static void dm_wq_work(struct work_struct *work);
@@ -1483,6 +1522,12 @@ static void cleanup_mapped_device(struct mapped_device *md) 
	if (md->bs)

		bioset_free(md->bs);



	if (md->dax_dev) {

		kill_dax(md->dax_dev);

		put_dax(md->dax_dev);

		md->dax_dev = NULL;

	}



	if (md->disk) {

		spin_lock(&_minor_lock);

		md->disk->private_data = NULL;
@@ -1510,6 +1555,7 @@ static void cleanup_mapped_device(struct mapped_device *md) 
static struct mapped_device *alloc_dev(int minor)

{

	int r, numa_node_id = dm_get_numa_node();

	struct dax_device *dax_dev;

	struct mapped_device *md;

	void *old_md;
@@ -1574,6 +1620,12 @@ static struct mapped_device *alloc_dev(int minor) 
	md->disk->queue = md->queue;

	md->disk->private_data = md;

	sprintf(md->disk->disk_name, "dm-%d", minor);



	dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);

	if (!dax_dev)

		goto bad;

	md->dax_dev = dax_dev;



	add_disk(md->disk);

	format_dev_t(md->name, MKDEV(_major, minor));
@@ -2781,6 +2833,10 @@ static const struct block_device_operations dm_blk_dops = { 
	.owner = THIS_MODULE

};



static const struct dax_operations dm_dax_ops = {

	.direct_access = dm_dax_direct_access,

};



/*

 * module hooks

 */

include/linux/device-mapper.h

+1 −0
Original line number Diff line number Diff line
@@ -130,6 +130,7 @@ typedef int (*dm_busy_fn) (struct dm_target *ti); 
 */

typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,

				     void **kaddr, pfn_t *pfn, long size);

#define PAGE_SECTORS (PAGE_SIZE / 512)



void dm_error(const char *message);