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: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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@ -200,6 +200,7 @@ config BLK_DEV_DM_BUILTIN
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config BLK_DEV_DM
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tristate "Device mapper support"
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select BLK_DEV_DM_BUILTIN
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select DAX
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---help---
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Device-mapper is a low level volume manager. It works by allowing
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people to specify mappings for ranges of logical sectors. Various
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@ -58,6 +58,7 @@ struct mapped_device {
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struct target_type *immutable_target_type;
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struct gendisk *disk;
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struct dax_device *dax_dev;
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char name[16];
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void *interface_ptr;
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@ -16,6 +16,7 @@
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#include <linux/blkpg.h>
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#include <linux/bio.h>
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#include <linux/mempool.h>
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#include <linux/dax.h>
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#include <linux/slab.h>
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#include <linux/idr.h>
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#include <linux/hdreg.h>
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@ -908,31 +909,68 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
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}
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EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
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static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,
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void **kaddr, pfn_t *pfn, long size)
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static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
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sector_t sector, int *srcu_idx)
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{
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struct mapped_device *md = bdev->bd_disk->private_data;
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struct dm_table *map;
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struct dm_target *ti;
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int srcu_idx;
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long len, ret = -EIO;
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map = dm_get_live_table(md, &srcu_idx);
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map = dm_get_live_table(md, srcu_idx);
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if (!map)
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goto out;
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return NULL;
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ti = dm_table_find_target(map, sector);
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if (!dm_target_is_valid(ti))
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return NULL;
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return ti;
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}
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static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
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long nr_pages, void **kaddr, pfn_t *pfn)
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{
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struct mapped_device *md = dax_get_private(dax_dev);
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sector_t sector = pgoff * PAGE_SECTORS;
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struct dm_target *ti;
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long len, ret = -EIO;
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int srcu_idx;
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ti = dm_dax_get_live_target(md, sector, &srcu_idx);
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if (!ti)
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goto out;
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len = max_io_len(sector, ti) << SECTOR_SHIFT;
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size = min(len, size);
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if (ti->type->direct_access)
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ret = ti->type->direct_access(ti, sector, kaddr, pfn, size);
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out:
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if (!ti->type->direct_access)
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goto out;
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len = max_io_len(sector, ti) / PAGE_SECTORS;
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if (len < 1)
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goto out;
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nr_pages = min(len, nr_pages);
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if (ti->type->direct_access) {
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ret = ti->type->direct_access(ti, sector, kaddr, pfn,
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nr_pages * PAGE_SIZE);
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/*
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* FIXME: convert ti->type->direct_access to return
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* nr_pages directly.
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*/
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if (ret >= 0)
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ret /= PAGE_SIZE;
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}
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out:
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dm_put_live_table(md, srcu_idx);
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return min(ret, size);
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return ret;
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}
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static long dm_blk_direct_access(struct block_device *bdev, sector_t sector,
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void **kaddr, pfn_t *pfn, long size)
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{
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struct mapped_device *md = bdev->bd_disk->private_data;
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struct dax_device *dax_dev = md->dax_dev;
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long nr_pages = size / PAGE_SIZE;
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nr_pages = dm_dax_direct_access(dax_dev, sector / PAGE_SECTORS,
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nr_pages, kaddr, pfn);
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return nr_pages < 0 ? nr_pages : nr_pages * PAGE_SIZE;
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}
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/*
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@ -1437,6 +1475,7 @@ static int next_free_minor(int *minor)
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}
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static const struct block_device_operations dm_blk_dops;
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static const struct dax_operations dm_dax_ops;
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static void dm_wq_work(struct work_struct *work);
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@ -1483,6 +1522,12 @@ static void cleanup_mapped_device(struct mapped_device *md)
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if (md->bs)
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bioset_free(md->bs);
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if (md->dax_dev) {
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kill_dax(md->dax_dev);
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put_dax(md->dax_dev);
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md->dax_dev = NULL;
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}
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if (md->disk) {
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spin_lock(&_minor_lock);
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md->disk->private_data = NULL;
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@ -1510,6 +1555,7 @@ static void cleanup_mapped_device(struct mapped_device *md)
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static struct mapped_device *alloc_dev(int minor)
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{
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int r, numa_node_id = dm_get_numa_node();
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struct dax_device *dax_dev;
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struct mapped_device *md;
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void *old_md;
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@ -1574,6 +1620,12 @@ static struct mapped_device *alloc_dev(int minor)
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md->disk->queue = md->queue;
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md->disk->private_data = md;
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sprintf(md->disk->disk_name, "dm-%d", minor);
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dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
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if (!dax_dev)
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goto bad;
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md->dax_dev = dax_dev;
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add_disk(md->disk);
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format_dev_t(md->name, MKDEV(_major, minor));
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@ -2781,6 +2833,10 @@ static const struct block_device_operations dm_blk_dops = {
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.owner = THIS_MODULE
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};
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static const struct dax_operations dm_dax_ops = {
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.direct_access = dm_dax_direct_access,
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};
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/*
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* module hooks
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*/
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@ -130,6 +130,7 @@ typedef int (*dm_busy_fn) (struct dm_target *ti);
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*/
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typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
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void **kaddr, pfn_t *pfn, long size);
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#define PAGE_SECTORS (PAGE_SIZE / 512)
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void dm_error(const char *message);
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