[resend PATCH v2 12/33] dm: teach dm-targets to use a dax_device + dax_operations

From: Dan Williams
Date: Mon Apr 17 2017 - 15:23:20 EST


Arrange for dm to lookup the dax services available from member devices.
Update the dax-capable targets, linear and stripe, to route dax
operations to the underlying device. Changes the target-internal
->direct_access() method to more closely align with the dax_operations
->direct_access() calling convention.

Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/md/dm-linear.c | 27 +++++++++++++--------------
drivers/md/dm-snap.c | 6 +++---
drivers/md/dm-stripe.c | 29 ++++++++++++++---------------
drivers/md/dm-target.c | 6 +++---
drivers/md/dm.c | 16 ++++++----------
include/linux/device-mapper.h | 7 ++++---
6 files changed, 43 insertions(+), 48 deletions(-)

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 4788b0b989a9..c5a52f4dae81 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -9,6 +9,7 @@
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
+#include <linux/dax.h>
#include <linux/slab.h>
#include <linux/device-mapper.h>

@@ -141,22 +142,20 @@ static int linear_iterate_devices(struct dm_target *ti,
return fn(ti, lc->dev, lc->start, ti->len, data);
}

-static long linear_direct_access(struct dm_target *ti, sector_t sector,
- void **kaddr, pfn_t *pfn, long size)
+static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
{
+ long ret;
struct linear_c *lc = ti->private;
struct block_device *bdev = lc->dev->bdev;
- struct blk_dax_ctl dax = {
- .sector = linear_map_sector(ti, sector),
- .size = size,
- };
- long ret;
-
- ret = bdev_direct_access(bdev, &dax);
- *kaddr = dax.addr;
- *pfn = dax.pfn;
-
- return ret;
+ struct dax_device *dax_dev = lc->dev->dax_dev;
+ sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+ dev_sector = linear_map_sector(ti, sector);
+ ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
+ if (ret)
+ return ret;
+ return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
}

static struct target_type linear_target = {
@@ -169,7 +168,7 @@ static struct target_type linear_target = {
.status = linear_status,
.prepare_ioctl = linear_prepare_ioctl,
.iterate_devices = linear_iterate_devices,
- .direct_access = linear_direct_access,
+ .direct_access = linear_dax_direct_access,
};

int __init dm_linear_init(void)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c65feeada864..e152d9817c81 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -2302,8 +2302,8 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
return do_origin(o->dev, bio);
}

-static long origin_direct_access(struct dm_target *ti, sector_t sector,
- void **kaddr, pfn_t *pfn, long size)
+static long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
{
DMWARN("device does not support dax.");
return -EIO;
@@ -2368,7 +2368,7 @@ static struct target_type origin_target = {
.postsuspend = origin_postsuspend,
.status = origin_status,
.iterate_devices = origin_iterate_devices,
- .direct_access = origin_direct_access,
+ .direct_access = origin_dax_direct_access,
};

static struct target_type snapshot_target = {
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 28193a57bf47..cb4b1e9e16ab 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -11,6 +11,7 @@
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
+#include <linux/dax.h>
#include <linux/slab.h>
#include <linux/log2.h>

@@ -308,27 +309,25 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
return DM_MAPIO_REMAPPED;
}

-static long stripe_direct_access(struct dm_target *ti, sector_t sector,
- void **kaddr, pfn_t *pfn, long size)
+static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
{
+ sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
struct stripe_c *sc = ti->private;
- uint32_t stripe;
+ struct dax_device *dax_dev;
struct block_device *bdev;
- struct blk_dax_ctl dax = {
- .size = size,
- };
+ uint32_t stripe;
long ret;

- stripe_map_sector(sc, sector, &stripe, &dax.sector);
-
- dax.sector += sc->stripe[stripe].physical_start;
+ stripe_map_sector(sc, sector, &stripe, &dev_sector);
+ dev_sector += sc->stripe[stripe].physical_start;
+ dax_dev = sc->stripe[stripe].dev->dax_dev;
bdev = sc->stripe[stripe].dev->bdev;

- ret = bdev_direct_access(bdev, &dax);
- *kaddr = dax.addr;
- *pfn = dax.pfn;
-
- return ret;
+ ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
+ if (ret)
+ return ret;
+ return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
}

/*
@@ -448,7 +447,7 @@ static struct target_type stripe_target = {
.status = stripe_status,
.iterate_devices = stripe_iterate_devices,
.io_hints = stripe_io_hints,
- .direct_access = stripe_direct_access,
+ .direct_access = stripe_dax_direct_access,
};

int __init dm_stripe_init(void)
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 43d3445b121d..6a7968f93f3c 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -142,8 +142,8 @@ static void io_err_release_clone_rq(struct request *clone)
{
}

-static long io_err_direct_access(struct dm_target *ti, sector_t sector,
- void **kaddr, pfn_t *pfn, long size)
+static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
{
return -EIO;
}
@@ -157,7 +157,7 @@ static struct target_type error_target = {
.map = io_err_map,
.clone_and_map_rq = io_err_clone_and_map_rq,
.release_clone_rq = io_err_release_clone_rq,
- .direct_access = io_err_direct_access,
+ .direct_access = io_err_dax_direct_access,
};

int __init dm_target_init(void)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index bd56dfe43a99..ef4c6f8cad47 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -630,6 +630,7 @@ static int open_table_device(struct table_device *td, dev_t dev,
}

td->dm_dev.bdev = bdev;
+ td->dm_dev.dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
return 0;
}

@@ -643,7 +644,9 @@ static void close_table_device(struct table_device *td, struct mapped_device *md

bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
+ put_dax(td->dm_dev.dax_dev);
td->dm_dev.bdev = NULL;
+ td->dm_dev.dax_dev = NULL;
}

static struct table_device *find_table_device(struct list_head *l, dev_t dev,
@@ -945,16 +948,9 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
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;
- }
+ if (ti->type->direct_access)
+ ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn);
+
out:
dm_put_live_table(md, srcu_idx);

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index bcba4d89089c..df830d167892 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -128,14 +128,15 @@ typedef int (*dm_busy_fn) (struct dm_target *ti);
* < 0 : error
* >= 0 : the number of bytes accessible at the address
*/
-typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
- void **kaddr, pfn_t *pfn, long size);
+typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn);
#define PAGE_SECTORS (PAGE_SIZE / 512)

void dm_error(const char *message);

struct dm_dev {
struct block_device *bdev;
+ struct dax_device *dax_dev;
fmode_t mode;
char name[16];
};
@@ -177,7 +178,7 @@ struct target_type {
dm_busy_fn busy;
dm_iterate_devices_fn iterate_devices;
dm_io_hints_fn io_hints;
- dm_direct_access_fn direct_access;
+ dm_dax_direct_access_fn direct_access;

/* For internal device-mapper use. */
struct list_head list;