[PATCH] dm: enable opt-out of device-mapper dax support

[PATCH] dm: enable opt-out of device-mapper dax support

[Dan Williams]

Now that dax is no longer a default property of a block-device, i.e.
->direct_access() is not a block-device operation, we optionally enable
device-mapper dax support with a new CONFIG_DM_DAX option.

All the dax operations helpers are moved to a new file,
drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
Otherwise, we stub out all the operations with NULL function pointers
and nop wrappers for the core dax routines.

Cc: Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Reported-by: Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>
Signed-off-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/md/Kconfig     |   14 +++
 drivers/md/Makefile    |    1 
 drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/md/dm-dax.h    |   73 +++++++++++++++
 drivers/md/dm-linear.c |   56 ------------
 drivers/md/dm-snap.c   |    9 --
 drivers/md/dm-stripe.c |   89 -------------------
 drivers/md/dm-target.c |    7 -
 drivers/md/dm.c        |  105 ++--------------------
 drivers/md/dm.h        |   34 +++++++
 10 files changed, 363 insertions(+), 252 deletions(-)
 create mode 100644 drivers/md/dm-dax.c
 create mode 100644 drivers/md/dm-dax.h

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..bf27b435f7cd 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
@@ -214,6 +213,19 @@ config BLK_DEV_DM
 
 	  If unsure, say N.
 
+config DM_DAX
+	bool "Direct access (DAX) support"
+	depends on BLK_DEV_DM
+	default BLK_DEV_PMEM
+	select DAX
+	---help---
+	  Enable DAX support for the device-mapper linear and stripe
+	  targets for use with DAX capable block devices like /dev/pmemN.
+	  If you have a DAX capable block device and have enabled
+	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
+
+	  If unsure, say N.
+
 config DM_MQ_DEFAULT
 	bool "request-based DM: use blk-mq I/O path by default"
 	depends on BLK_DEV_DM
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 786ec9e86d65..4a2fd958a3d9 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -5,6 +5,7 @@
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
 		   dm-rq.o
+dm-mod-$(CONFIG_DM_DAX) += dm-dax.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
 		    dm-snap-persistent.o
diff --git a/drivers/md/dm-dax.c b/drivers/md/dm-dax.c
new file mode 100644
index 000000000000..d48386fe2578
--- /dev/null
+++ b/drivers/md/dm-dax.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device-mapper.h>
+#include <linux/dax.h>
+#include <linux/uio.h>
+
+#include "dm.h"
+
+extern sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector);
+extern sector_t max_io_len(sector_t sector, struct dm_target *ti);
+
+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 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);
+}
+
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+#define DM_MSG_PREFIX "snapshots"
+	DMWARN("device does not support dax.");
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(origin_dax_direct_access);
+
+extern void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+			      uint32_t *stripe, sector_t *result);
+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;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+	long ret;
+
+	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_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);
+}
+
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+	return -EIO;
+}
+
+static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
+		sector_t sector, int *srcu_idx)
+{
+	struct dm_table *map;
+	struct dm_target *ti;
+
+	map = dm_get_live_table(md, srcu_idx);
+	if (!map)
+		return NULL;
+
+	ti = dm_table_find_target(map, sector);
+	if (!dm_target_is_valid(ti))
+		return NULL;
+
+	return ti;
+}
+
+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)
+		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, pgoff, nr_pages, kaddr, pfn);
+
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	long ret = 0;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (!ti->type->dax_copy_from_iter) {
+		ret = copy_from_iter(addr, bytes, i);
+		goto out;
+	}
+	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (ti->type->dax_flush)
+		ti->type->dax_flush(ti, pgoff, addr, size);
+ out:
+	dm_put_live_table(md, srcu_idx);
+}
diff --git a/drivers/md/dm-dax.h b/drivers/md/dm-dax.h
new file mode 100644
index 000000000000..02cd4589d05a
--- /dev/null
+++ b/drivers/md/dm-dax.h
@@ -0,0 +1,73 @@
+#ifndef __DM_DAX_H__
+#define __DM_DAX_H__
+#include <linux/dax.h>
+#if IS_ENABLED(CONFIG_DM_DAX)
+/* dax helpers to allow compiling out dax support */
+long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return dax_get_by_host(host);
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+	put_dax(dax_dev);
+}
+static inline struct dax_device *dm_alloc_dax(void *p, const char *host,
+		const struct dax_operations *ops)
+{
+	return alloc_dax(p, host, ops);
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+	kill_dax(dax_dev);
+}
+long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size);
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#define origin_dax_direct_access NULL
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#define io_err_dax_direct_access NULL
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return NULL;
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+}
+static inline struct dax_device *dm_alloc_dax(void *private, const char *__host,
+		const struct dax_operations *ops)
+{
+	return NULL;
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+}
+#define dm_dax_direct_access NULL
+#define dm_dax_copy_from_iter NULL
+#define dm_dax_flush NULL
+#endif
+#endif /* __DM_DAX_H__ */
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..184ae6e76ac4 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -5,25 +5,17 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/module.h>
 #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>
 
 #define DM_MSG_PREFIX "linear"
 
 /*
- * Linear: maps a linear range of a device.
- */
-struct linear_c {
-	struct dm_dev *dev;
-	sector_t start;
-};
-
-/*
  * Construct a linear mapping: <dev_path> <offset>
  */
 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
@@ -77,7 +69,7 @@ static void linear_dtr(struct dm_target *ti)
 	kfree(lc);
 }
 
-static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
+sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
 	struct linear_c *lc = ti->private;
 
@@ -154,50 +146,6 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
-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 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 size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 static struct target_type linear_target = {
 	.name   = "linear",
 	.version = {1, 4, 0},
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba41048b438..fa31d9f5642d 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -21,7 +21,7 @@
 #include <linux/dm-kcopyd.h>
 
 #include "dm.h"
-
+#include "dm-dax.h"
 #include "dm-exception-store.h"
 
 #define DM_MSG_PREFIX "snapshots"
@@ -2303,13 +2303,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
 	return do_origin(o->dev, bio);
 }
 
-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;
-}
-
 /*
  * Set the target "max_io_len" field to the minimum of all the snapshots'
  * chunk sizes.
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..a4720abac523 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -5,45 +5,19 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/device-mapper.h>
 
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/bio.h>
-#include <linux/dax.h>
 #include <linux/slab.h>
 #include <linux/log2.h>
 
 #define DM_MSG_PREFIX "striped"
 #define DM_IO_ERROR_THRESHOLD 15
 
-struct stripe {
-	struct dm_dev *dev;
-	sector_t physical_start;
-
-	atomic_t error_count;
-};
-
-struct stripe_c {
-	uint32_t stripes;
-	int stripes_shift;
-
-	/* The size of this target / num. stripes */
-	sector_t stripe_width;
-
-	uint32_t chunk_size;
-	int chunk_size_shift;
-
-	/* Needed for handling events */
-	struct dm_target *ti;
-
-	/* Work struct used for triggering events*/
-	struct work_struct trigger_event;
-
-	struct stripe stripe[0];
-};
-
 /*
  * An event is triggered whenever a drive
  * drops out of a stripe volume.
@@ -212,7 +186,7 @@ static void stripe_dtr(struct dm_target *ti)
 	kfree(sc);
 }
 
-static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 			      uint32_t *stripe, sector_t *result)
 {
 	sector_t chunk = dm_target_offset(sc->ti, sector);
@@ -311,65 +285,6 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
-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;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-	long ret;
-
-	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_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 size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 /*
  * Stripe status:
  *
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index c0d7e60820c4..3d4130e2e1e9 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -5,6 +5,7 @@
  */
 
 #include "dm-core.h"
+#include "dm-dax.h"
 
 #include <linux/module.h>
 #include <linux/init.h>
@@ -142,12 +143,6 @@ static void io_err_release_clone_rq(struct request *clone)
 {
 }
 
-static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-		long nr_pages, void **kaddr, pfn_t *pfn)
-{
-	return -EIO;
-}
-
 static struct target_type error_target = {
 	.name = "error",
 	.version = {1, 5, 0},
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..73aca9ce5581 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -8,6 +8,7 @@
 #include "dm-core.h"
 #include "dm-rq.h"
 #include "dm-uevent.h"
+#include "dm-dax.h"
 
 #include <linux/init.h>
 #include <linux/module.h>
@@ -16,7 +17,6 @@
 #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/uio.h>
@@ -634,7 +634,7 @@ 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);
+	td->dm_dev.dax_dev = dm_dax_get_by_host(bdev->bd_disk->disk_name);
 	return 0;
 }
 
@@ -648,7 +648,7 @@ 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);
+	dm_put_dax(td->dm_dev.dax_dev);
 	td->dm_dev.bdev = NULL;
 	td->dm_dev.dax_dev = NULL;
 }
@@ -890,7 +890,7 @@ static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti
 	return ti->len - target_offset;
 }
 
-static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+sector_t max_io_len(sector_t sector, struct dm_target *ti)
 {
 	sector_t len = max_io_len_target_boundary(sector, ti);
 	sector_t offset, max_len;
@@ -928,93 +928,6 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
 }
 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
 
-static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
-		sector_t sector, int *srcu_idx)
-{
-	struct dm_table *map;
-	struct dm_target *ti;
-
-	map = dm_get_live_table(md, srcu_idx);
-	if (!map)
-		return NULL;
-
-	ti = dm_table_find_target(map, sector);
-	if (!dm_target_is_valid(ti))
-		return NULL;
-
-	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)
-		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, pgoff, nr_pages, kaddr, pfn);
-
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	long ret = 0;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (!ti->type->dax_copy_from_iter) {
-		ret = copy_from_iter(addr, bytes, i);
-		goto out;
-	}
-	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (ti->type->dax_flush)
-		ti->type->dax_flush(ti, pgoff, addr, size);
- out:
-	dm_put_live_table(md, srcu_idx);
-}
-
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
  * allowed for all bio types except REQ_PREFLUSH.
@@ -1681,8 +1594,8 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		bioset_free(md->bs);
 
 	if (md->dax_dev) {
-		kill_dax(md->dax_dev);
-		put_dax(md->dax_dev);
+		dm_kill_dax(md->dax_dev);
+		dm_put_dax(md->dax_dev);
 		md->dax_dev = NULL;
 	}
 
@@ -1779,8 +1692,8 @@ static struct mapped_device *alloc_dev(int minor)
 	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)
+	dax_dev = dm_alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+	if (!dax_dev && IS_ENABLED(CONFIG_DM_DAX))
 		goto bad;
 	md->dax_dev = dax_dev;
 
@@ -2999,7 +2912,7 @@ static const struct block_device_operations dm_blk_dops = {
 	.owner = THIS_MODULE
 };
 
-static const struct dax_operations dm_dax_ops = {
+static const __maybe_unused struct dax_operations dm_dax_ops = {
 	.direct_access = dm_dax_direct_access,
 	.copy_from_iter = dm_dax_copy_from_iter,
 	.flush = dm_dax_flush,
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 38c84c0a35d4..2c9d94ec2391 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -174,6 +174,40 @@ int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
 /*
+ * Linear: maps a linear range of a device.
+ */
+struct linear_c {
+	struct dm_dev *dev;
+	sector_t start;
+};
+
+struct stripe {
+	struct dm_dev *dev;
+	sector_t physical_start;
+
+	atomic_t error_count;
+};
+
+struct stripe_c {
+	uint32_t stripes;
+	int stripes_shift;
+
+	/* The size of this target / num. stripes */
+	sector_t stripe_width;
+
+	uint32_t chunk_size;
+	int chunk_size_shift;
+
+	/* Needed for handling events */
+	struct dm_target *ti;
+
+	/* Work struct used for triggering events*/
+	struct work_struct trigger_event;
+
+	struct stripe stripe[0];
+};
+
+/*
  * mapped_device operations
  */
 void dm_destroy(struct mapped_device *md);

[PATCH] dm: enable opt-out of device-mapper dax support

[Dan Williams]

Now that dax is no longer a default property of a block-device, i.e.
->direct_access() is not a block-device operation, we optionally enable
device-mapper dax support with a new CONFIG_DM_DAX option.

All the dax operations helpers are moved to a new file,
drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
Otherwise, we stub out all the operations with NULL function pointers
and nop wrappers for the core dax routines.

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/md/Kconfig     |   14 +++
 drivers/md/Makefile    |    1 
 drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/md/dm-dax.h    |   73 +++++++++++++++
 drivers/md/dm-linear.c |   56 ------------
 drivers/md/dm-snap.c   |    9 --
 drivers/md/dm-stripe.c |   89 -------------------
 drivers/md/dm-target.c |    7 -
 drivers/md/dm.c        |  105 ++--------------------
 drivers/md/dm.h        |   34 +++++++
 10 files changed, 363 insertions(+), 252 deletions(-)
 create mode 100644 drivers/md/dm-dax.c
 create mode 100644 drivers/md/dm-dax.h

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..bf27b435f7cd 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
@@ -214,6 +213,19 @@ config BLK_DEV_DM
 
 	  If unsure, say N.
 
+config DM_DAX
+	bool "Direct access (DAX) support"
+	depends on BLK_DEV_DM
+	default BLK_DEV_PMEM
+	select DAX
+	---help---
+	  Enable DAX support for the device-mapper linear and stripe
+	  targets for use with DAX capable block devices like /dev/pmemN.
+	  If you have a DAX capable block device and have enabled
+	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
+
+	  If unsure, say N.
+
 config DM_MQ_DEFAULT
 	bool "request-based DM: use blk-mq I/O path by default"
 	depends on BLK_DEV_DM
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 786ec9e86d65..4a2fd958a3d9 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -5,6 +5,7 @@
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
 		   dm-rq.o
+dm-mod-$(CONFIG_DM_DAX) += dm-dax.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
 		    dm-snap-persistent.o
diff --git a/drivers/md/dm-dax.c b/drivers/md/dm-dax.c
new file mode 100644
index 000000000000..d48386fe2578
--- /dev/null
+++ b/drivers/md/dm-dax.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device-mapper.h>
+#include <linux/dax.h>
+#include <linux/uio.h>
+
+#include "dm.h"
+
+extern sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector);
+extern sector_t max_io_len(sector_t sector, struct dm_target *ti);
+
+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 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);
+}
+
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+#define DM_MSG_PREFIX "snapshots"
+	DMWARN("device does not support dax.");
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(origin_dax_direct_access);
+
+extern void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+			      uint32_t *stripe, sector_t *result);
+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;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+	long ret;
+
+	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_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);
+}
+
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+	return -EIO;
+}
+
+static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
+		sector_t sector, int *srcu_idx)
+{
+	struct dm_table *map;
+	struct dm_target *ti;
+
+	map = dm_get_live_table(md, srcu_idx);
+	if (!map)
+		return NULL;
+
+	ti = dm_table_find_target(map, sector);
+	if (!dm_target_is_valid(ti))
+		return NULL;
+
+	return ti;
+}
+
+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)
+		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, pgoff, nr_pages, kaddr, pfn);
+
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	long ret = 0;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (!ti->type->dax_copy_from_iter) {
+		ret = copy_from_iter(addr, bytes, i);
+		goto out;
+	}
+	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (ti->type->dax_flush)
+		ti->type->dax_flush(ti, pgoff, addr, size);
+ out:
+	dm_put_live_table(md, srcu_idx);
+}
diff --git a/drivers/md/dm-dax.h b/drivers/md/dm-dax.h
new file mode 100644
index 000000000000..02cd4589d05a
--- /dev/null
+++ b/drivers/md/dm-dax.h
@@ -0,0 +1,73 @@
+#ifndef __DM_DAX_H__
+#define __DM_DAX_H__
+#include <linux/dax.h>
+#if IS_ENABLED(CONFIG_DM_DAX)
+/* dax helpers to allow compiling out dax support */
+long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return dax_get_by_host(host);
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+	put_dax(dax_dev);
+}
+static inline struct dax_device *dm_alloc_dax(void *p, const char *host,
+		const struct dax_operations *ops)
+{
+	return alloc_dax(p, host, ops);
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+	kill_dax(dax_dev);
+}
+long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size);
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#define origin_dax_direct_access NULL
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#define io_err_dax_direct_access NULL
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return NULL;
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+}
+static inline struct dax_device *dm_alloc_dax(void *private, const char *__host,
+		const struct dax_operations *ops)
+{
+	return NULL;
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+}
+#define dm_dax_direct_access NULL
+#define dm_dax_copy_from_iter NULL
+#define dm_dax_flush NULL
+#endif
+#endif /* __DM_DAX_H__ */
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..184ae6e76ac4 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -5,25 +5,17 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/module.h>
 #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>
 
 #define DM_MSG_PREFIX "linear"
 
 /*
- * Linear: maps a linear range of a device.
- */
-struct linear_c {
-	struct dm_dev *dev;
-	sector_t start;
-};
-
-/*
  * Construct a linear mapping: <dev_path> <offset>
  */
 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
@@ -77,7 +69,7 @@ static void linear_dtr(struct dm_target *ti)
 	kfree(lc);
 }
 
-static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
+sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
 	struct linear_c *lc = ti->private;
 
@@ -154,50 +146,6 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
-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 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 size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 static struct target_type linear_target = {
 	.name   = "linear",
 	.version = {1, 4, 0},
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba41048b438..fa31d9f5642d 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -21,7 +21,7 @@
 #include <linux/dm-kcopyd.h>
 
 #include "dm.h"
-
+#include "dm-dax.h"
 #include "dm-exception-store.h"
 
 #define DM_MSG_PREFIX "snapshots"
@@ -2303,13 +2303,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
 	return do_origin(o->dev, bio);
 }
 
-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;
-}
-
 /*
  * Set the target "max_io_len" field to the minimum of all the snapshots'
  * chunk sizes.
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..a4720abac523 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -5,45 +5,19 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/device-mapper.h>
 
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/bio.h>
-#include <linux/dax.h>
 #include <linux/slab.h>
 #include <linux/log2.h>
 
 #define DM_MSG_PREFIX "striped"
 #define DM_IO_ERROR_THRESHOLD 15
 
-struct stripe {
-	struct dm_dev *dev;
-	sector_t physical_start;
-
-	atomic_t error_count;
-};
-
-struct stripe_c {
-	uint32_t stripes;
-	int stripes_shift;
-
-	/* The size of this target / num. stripes */
-	sector_t stripe_width;
-
-	uint32_t chunk_size;
-	int chunk_size_shift;
-
-	/* Needed for handling events */
-	struct dm_target *ti;
-
-	/* Work struct used for triggering events*/
-	struct work_struct trigger_event;
-
-	struct stripe stripe[0];
-};
-
 /*
  * An event is triggered whenever a drive
  * drops out of a stripe volume.
@@ -212,7 +186,7 @@ static void stripe_dtr(struct dm_target *ti)
 	kfree(sc);
 }
 
-static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 			      uint32_t *stripe, sector_t *result)
 {
 	sector_t chunk = dm_target_offset(sc->ti, sector);
@@ -311,65 +285,6 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
-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;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-	long ret;
-
-	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_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 size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 /*
  * Stripe status:
  *
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index c0d7e60820c4..3d4130e2e1e9 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -5,6 +5,7 @@
  */
 
 #include "dm-core.h"
+#include "dm-dax.h"
 
 #include <linux/module.h>
 #include <linux/init.h>
@@ -142,12 +143,6 @@ static void io_err_release_clone_rq(struct request *clone)
 {
 }
 
-static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-		long nr_pages, void **kaddr, pfn_t *pfn)
-{
-	return -EIO;
-}
-
 static struct target_type error_target = {
 	.name = "error",
 	.version = {1, 5, 0},
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..73aca9ce5581 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -8,6 +8,7 @@
 #include "dm-core.h"
 #include "dm-rq.h"
 #include "dm-uevent.h"
+#include "dm-dax.h"
 
 #include <linux/init.h>
 #include <linux/module.h>
@@ -16,7 +17,6 @@
 #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/uio.h>
@@ -634,7 +634,7 @@ 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);
+	td->dm_dev.dax_dev = dm_dax_get_by_host(bdev->bd_disk->disk_name);
 	return 0;
 }
 
@@ -648,7 +648,7 @@ 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);
+	dm_put_dax(td->dm_dev.dax_dev);
 	td->dm_dev.bdev = NULL;
 	td->dm_dev.dax_dev = NULL;
 }
@@ -890,7 +890,7 @@ static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti
 	return ti->len - target_offset;
 }
 
-static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+sector_t max_io_len(sector_t sector, struct dm_target *ti)
 {
 	sector_t len = max_io_len_target_boundary(sector, ti);
 	sector_t offset, max_len;
@@ -928,93 +928,6 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
 }
 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
 
-static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
-		sector_t sector, int *srcu_idx)
-{
-	struct dm_table *map;
-	struct dm_target *ti;
-
-	map = dm_get_live_table(md, srcu_idx);
-	if (!map)
-		return NULL;
-
-	ti = dm_table_find_target(map, sector);
-	if (!dm_target_is_valid(ti))
-		return NULL;
-
-	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)
-		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, pgoff, nr_pages, kaddr, pfn);
-
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	long ret = 0;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (!ti->type->dax_copy_from_iter) {
-		ret = copy_from_iter(addr, bytes, i);
-		goto out;
-	}
-	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (ti->type->dax_flush)
-		ti->type->dax_flush(ti, pgoff, addr, size);
- out:
-	dm_put_live_table(md, srcu_idx);
-}
-
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
  * allowed for all bio types except REQ_PREFLUSH.
@@ -1681,8 +1594,8 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		bioset_free(md->bs);
 
 	if (md->dax_dev) {
-		kill_dax(md->dax_dev);
-		put_dax(md->dax_dev);
+		dm_kill_dax(md->dax_dev);
+		dm_put_dax(md->dax_dev);
 		md->dax_dev = NULL;
 	}
 
@@ -1779,8 +1692,8 @@ static struct mapped_device *alloc_dev(int minor)
 	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)
+	dax_dev = dm_alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+	if (!dax_dev && IS_ENABLED(CONFIG_DM_DAX))
 		goto bad;
 	md->dax_dev = dax_dev;
 
@@ -2999,7 +2912,7 @@ static const struct block_device_operations dm_blk_dops = {
 	.owner = THIS_MODULE
 };
 
-static const struct dax_operations dm_dax_ops = {
+static const __maybe_unused struct dax_operations dm_dax_ops = {
 	.direct_access = dm_dax_direct_access,
 	.copy_from_iter = dm_dax_copy_from_iter,
 	.flush = dm_dax_flush,
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 38c84c0a35d4..2c9d94ec2391 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -174,6 +174,40 @@ int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
 /*
+ * Linear: maps a linear range of a device.
+ */
+struct linear_c {
+	struct dm_dev *dev;
+	sector_t start;
+};
+
+struct stripe {
+	struct dm_dev *dev;
+	sector_t physical_start;
+
+	atomic_t error_count;
+};
+
+struct stripe_c {
+	uint32_t stripes;
+	int stripes_shift;
+
+	/* The size of this target / num. stripes */
+	sector_t stripe_width;
+
+	uint32_t chunk_size;
+	int chunk_size_shift;
+
+	/* Needed for handling events */
+	struct dm_target *ti;
+
+	/* Work struct used for triggering events*/
+	struct work_struct trigger_event;
+
+	struct stripe stripe[0];
+};
+
+/*
  * mapped_device operations
  */
 void dm_destroy(struct mapped_device *md);

[PATCH] dm: enable opt-out of device-mapper dax support

[Dan Williams]

Now that dax is no longer a default property of a block-device, i.e.
->direct_access() is not a block-device operation, we optionally enable
device-mapper dax support with a new CONFIG_DM_DAX option.

All the dax operations helpers are moved to a new file,
drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
Otherwise, we stub out all the operations with NULL function pointers
and nop wrappers for the core dax routines.

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/md/Kconfig     |   14 +++
 drivers/md/Makefile    |    1 
 drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/md/dm-dax.h    |   73 +++++++++++++++
 drivers/md/dm-linear.c |   56 ------------
 drivers/md/dm-snap.c   |    9 --
 drivers/md/dm-stripe.c |   89 -------------------
 drivers/md/dm-target.c |    7 -
 drivers/md/dm.c        |  105 ++--------------------
 drivers/md/dm.h        |   34 +++++++
 10 files changed, 363 insertions(+), 252 deletions(-)
 create mode 100644 drivers/md/dm-dax.c
 create mode 100644 drivers/md/dm-dax.h

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..bf27b435f7cd 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
@@ -214,6 +213,19 @@ config BLK_DEV_DM
 
 	  If unsure, say N.
 
+config DM_DAX
+	bool "Direct access (DAX) support"
+	depends on BLK_DEV_DM
+	default BLK_DEV_PMEM
+	select DAX
+	---help---
+	  Enable DAX support for the device-mapper linear and stripe
+	  targets for use with DAX capable block devices like /dev/pmemN.
+	  If you have a DAX capable block device and have enabled
+	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
+
+	  If unsure, say N.
+
 config DM_MQ_DEFAULT
 	bool "request-based DM: use blk-mq I/O path by default"
 	depends on BLK_DEV_DM
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 786ec9e86d65..4a2fd958a3d9 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -5,6 +5,7 @@
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
 		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
 		   dm-rq.o
+dm-mod-$(CONFIG_DM_DAX) += dm-dax.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
 		    dm-snap-persistent.o
diff --git a/drivers/md/dm-dax.c b/drivers/md/dm-dax.c
new file mode 100644
index 000000000000..d48386fe2578
--- /dev/null
+++ b/drivers/md/dm-dax.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/device-mapper.h>
+#include <linux/dax.h>
+#include <linux/uio.h>
+
+#include "dm.h"
+
+extern sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector);
+extern sector_t max_io_len(sector_t sector, struct dm_target *ti);
+
+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 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);
+}
+
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+#define DM_MSG_PREFIX "snapshots"
+	DMWARN("device does not support dax.");
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(origin_dax_direct_access);
+
+extern void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+			      uint32_t *stripe, sector_t *result);
+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;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+	long ret;
+
+	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_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);
+}
+
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	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;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
+		return;
+	dax_flush(dax_dev, pgoff, addr, size);
+}
+
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn)
+{
+	return -EIO;
+}
+
+static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
+		sector_t sector, int *srcu_idx)
+{
+	struct dm_table *map;
+	struct dm_target *ti;
+
+	map = dm_get_live_table(md, srcu_idx);
+	if (!map)
+		return NULL;
+
+	ti = dm_table_find_target(map, sector);
+	if (!dm_target_is_valid(ti))
+		return NULL;
+
+	return ti;
+}
+
+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)
+		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, pgoff, nr_pages, kaddr, pfn);
+
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	long ret = 0;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (!ti->type->dax_copy_from_iter) {
+		ret = copy_from_iter(addr, bytes, i);
+		goto out;
+	}
+	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (ti->type->dax_flush)
+		ti->type->dax_flush(ti, pgoff, addr, size);
+ out:
+	dm_put_live_table(md, srcu_idx);
+}
diff --git a/drivers/md/dm-dax.h b/drivers/md/dm-dax.h
new file mode 100644
index 000000000000..02cd4589d05a
--- /dev/null
+++ b/drivers/md/dm-dax.h
@@ -0,0 +1,73 @@
+#ifndef __DM_DAX_H__
+#define __DM_DAX_H__
+#include <linux/dax.h>
+#if IS_ENABLED(CONFIG_DM_DAX)
+/* dax helpers to allow compiling out dax support */
+long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
+		size_t size);
+long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return dax_get_by_host(host);
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+	put_dax(dax_dev);
+}
+static inline struct dax_device *dm_alloc_dax(void *p, const char *host,
+		const struct dax_operations *ops)
+{
+	return alloc_dax(p, host, ops);
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+	kill_dax(dax_dev);
+}
+long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+		long nr_pages, void **kaddr, pfn_t *pfn);
+size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
+void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t size);
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#define origin_dax_direct_access NULL
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#define io_err_dax_direct_access NULL
+static inline struct dax_device *dm_dax_get_by_host(const char *host)
+{
+	return NULL;
+}
+static inline void dm_put_dax(struct dax_device *dax_dev)
+{
+}
+static inline struct dax_device *dm_alloc_dax(void *private, const char *__host,
+		const struct dax_operations *ops)
+{
+	return NULL;
+}
+static inline void dm_kill_dax(struct dax_device *dax_dev)
+{
+}
+#define dm_dax_direct_access NULL
+#define dm_dax_copy_from_iter NULL
+#define dm_dax_flush NULL
+#endif
+#endif /* __DM_DAX_H__ */
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..184ae6e76ac4 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -5,25 +5,17 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/module.h>
 #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>
 
 #define DM_MSG_PREFIX "linear"
 
 /*
- * Linear: maps a linear range of a device.
- */
-struct linear_c {
-	struct dm_dev *dev;
-	sector_t start;
-};
-
-/*
  * Construct a linear mapping: <dev_path> <offset>
  */
 static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
@@ -77,7 +69,7 @@ static void linear_dtr(struct dm_target *ti)
 	kfree(lc);
 }
 
-static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
+sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
 	struct linear_c *lc = ti->private;
 
@@ -154,50 +146,6 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
-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 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 size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct linear_c *lc = ti->private;
-	struct block_device *bdev = lc->dev->bdev;
-	struct dax_device *dax_dev = lc->dev->dax_dev;
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-	dev_sector = linear_map_sector(ti, sector);
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 static struct target_type linear_target = {
 	.name   = "linear",
 	.version = {1, 4, 0},
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba41048b438..fa31d9f5642d 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -21,7 +21,7 @@
 #include <linux/dm-kcopyd.h>
 
 #include "dm.h"
-
+#include "dm-dax.h"
 #include "dm-exception-store.h"
 
 #define DM_MSG_PREFIX "snapshots"
@@ -2303,13 +2303,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
 	return do_origin(o->dev, bio);
 }
 
-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;
-}
-
 /*
  * Set the target "max_io_len" field to the minimum of all the snapshots'
  * chunk sizes.
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..a4720abac523 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -5,45 +5,19 @@
  */
 
 #include "dm.h"
+#include "dm-dax.h"
 #include <linux/device-mapper.h>
 
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/bio.h>
-#include <linux/dax.h>
 #include <linux/slab.h>
 #include <linux/log2.h>
 
 #define DM_MSG_PREFIX "striped"
 #define DM_IO_ERROR_THRESHOLD 15
 
-struct stripe {
-	struct dm_dev *dev;
-	sector_t physical_start;
-
-	atomic_t error_count;
-};
-
-struct stripe_c {
-	uint32_t stripes;
-	int stripes_shift;
-
-	/* The size of this target / num. stripes */
-	sector_t stripe_width;
-
-	uint32_t chunk_size;
-	int chunk_size_shift;
-
-	/* Needed for handling events */
-	struct dm_target *ti;
-
-	/* Work struct used for triggering events*/
-	struct work_struct trigger_event;
-
-	struct stripe stripe[0];
-};
-
 /*
  * An event is triggered whenever a drive
  * drops out of a stripe volume.
@@ -212,7 +186,7 @@ static void stripe_dtr(struct dm_target *ti)
 	kfree(sc);
 }
 
-static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 			      uint32_t *stripe, sector_t *result)
 {
 	sector_t chunk = dm_target_offset(sc->ti, sector);
@@ -311,65 +285,6 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
-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;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-	long ret;
-
-	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_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 size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-		return 0;
-	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
-}
-
-static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-	struct stripe_c *sc = ti->private;
-	struct dax_device *dax_dev;
-	struct block_device *bdev;
-	uint32_t stripe;
-
-	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;
-
-	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(size, PAGE_SIZE), &pgoff))
-		return;
-	dax_flush(dax_dev, pgoff, addr, size);
-}
-
 /*
  * Stripe status:
  *
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index c0d7e60820c4..3d4130e2e1e9 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -5,6 +5,7 @@
  */
 
 #include "dm-core.h"
+#include "dm-dax.h"
 
 #include <linux/module.h>
 #include <linux/init.h>
@@ -142,12 +143,6 @@ static void io_err_release_clone_rq(struct request *clone)
 {
 }
 
-static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-		long nr_pages, void **kaddr, pfn_t *pfn)
-{
-	return -EIO;
-}
-
 static struct target_type error_target = {
 	.name = "error",
 	.version = {1, 5, 0},
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..73aca9ce5581 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -8,6 +8,7 @@
 #include "dm-core.h"
 #include "dm-rq.h"
 #include "dm-uevent.h"
+#include "dm-dax.h"
 
 #include <linux/init.h>
 #include <linux/module.h>
@@ -16,7 +17,6 @@
 #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/uio.h>
@@ -634,7 +634,7 @@ 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);
+	td->dm_dev.dax_dev = dm_dax_get_by_host(bdev->bd_disk->disk_name);
 	return 0;
 }
 
@@ -648,7 +648,7 @@ 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);
+	dm_put_dax(td->dm_dev.dax_dev);
 	td->dm_dev.bdev = NULL;
 	td->dm_dev.dax_dev = NULL;
 }
@@ -890,7 +890,7 @@ static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti
 	return ti->len - target_offset;
 }
 
-static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+sector_t max_io_len(sector_t sector, struct dm_target *ti)
 {
 	sector_t len = max_io_len_target_boundary(sector, ti);
 	sector_t offset, max_len;
@@ -928,93 +928,6 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
 }
 EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
 
-static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
-		sector_t sector, int *srcu_idx)
-{
-	struct dm_table *map;
-	struct dm_target *ti;
-
-	map = dm_get_live_table(md, srcu_idx);
-	if (!map)
-		return NULL;
-
-	ti = dm_table_find_target(map, sector);
-	if (!dm_target_is_valid(ti))
-		return NULL;
-
-	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)
-		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, pgoff, nr_pages, kaddr, pfn);
-
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-		void *addr, size_t bytes, struct iov_iter *i)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	long ret = 0;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (!ti->type->dax_copy_from_iter) {
-		ret = copy_from_iter(addr, bytes, i);
-		goto out;
-	}
-	ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
- out:
-	dm_put_live_table(md, srcu_idx);
-
-	return ret;
-}
-
-static void dm_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
-		size_t size)
-{
-	struct mapped_device *md = dax_get_private(dax_dev);
-	sector_t sector = pgoff * PAGE_SECTORS;
-	struct dm_target *ti;
-	int srcu_idx;
-
-	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
-
-	if (!ti)
-		goto out;
-	if (ti->type->dax_flush)
-		ti->type->dax_flush(ti, pgoff, addr, size);
- out:
-	dm_put_live_table(md, srcu_idx);
-}
-
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
  * allowed for all bio types except REQ_PREFLUSH.
@@ -1681,8 +1594,8 @@ static void cleanup_mapped_device(struct mapped_device *md)
 		bioset_free(md->bs);
 
 	if (md->dax_dev) {
-		kill_dax(md->dax_dev);
-		put_dax(md->dax_dev);
+		dm_kill_dax(md->dax_dev);
+		dm_put_dax(md->dax_dev);
 		md->dax_dev = NULL;
 	}
 
@@ -1779,8 +1692,8 @@ static struct mapped_device *alloc_dev(int minor)
 	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)
+	dax_dev = dm_alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+	if (!dax_dev && IS_ENABLED(CONFIG_DM_DAX))
 		goto bad;
 	md->dax_dev = dax_dev;
 
@@ -2999,7 +2912,7 @@ static const struct block_device_operations dm_blk_dops = {
 	.owner = THIS_MODULE
 };
 
-static const struct dax_operations dm_dax_ops = {
+static const __maybe_unused struct dax_operations dm_dax_ops = {
 	.direct_access = dm_dax_direct_access,
 	.copy_from_iter = dm_dax_copy_from_iter,
 	.flush = dm_dax_flush,
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 38c84c0a35d4..2c9d94ec2391 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -174,6 +174,40 @@ int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
 /*
+ * Linear: maps a linear range of a device.
+ */
+struct linear_c {
+	struct dm_dev *dev;
+	sector_t start;
+};
+
+struct stripe {
+	struct dm_dev *dev;
+	sector_t physical_start;
+
+	atomic_t error_count;
+};
+
+struct stripe_c {
+	uint32_t stripes;
+	int stripes_shift;
+
+	/* The size of this target / num. stripes */
+	sector_t stripe_width;
+
+	uint32_t chunk_size;
+	int chunk_size_shift;
+
+	/* Needed for handling events */
+	struct dm_target *ti;
+
+	/* Work struct used for triggering events*/
+	struct work_struct trigger_event;
+
+	struct stripe stripe[0];
+};
+
+/*
  * mapped_device operations
  */
 void dm_destroy(struct mapped_device *md);

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Re: dm: enable opt-out of device-mapper dax support

[Mike Snitzer]

On Tue, Aug 01 2017 at  2:12pm -0400,
Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:

> Now that dax is no longer a default property of a block-device, i.e.
> ->direct_access() is not a block-device operation, we optionally enable
> device-mapper dax support with a new CONFIG_DM_DAX option.
> 
> All the dax operations helpers are moved to a new file,
> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
> Otherwise, we stub out all the operations with NULL function pointers
> and nop wrappers for the core dax routines.
> 
> Cc: Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Reported-by: Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>
> Signed-off-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/md/Kconfig     |   14 +++
>  drivers/md/Makefile    |    1 
>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>  drivers/md/dm-linear.c |   56 ------------
>  drivers/md/dm-snap.c   |    9 --
>  drivers/md/dm-stripe.c |   89 -------------------
>  drivers/md/dm-target.c |    7 -
>  drivers/md/dm.c        |  105 ++--------------------
>  drivers/md/dm.h        |   34 +++++++
>  10 files changed, 363 insertions(+), 252 deletions(-)
>  create mode 100644 drivers/md/dm-dax.c
>  create mode 100644 drivers/md/dm-dax.h
> 
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 4a249ee86364..bf27b435f7cd 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -200,7 +200,6 @@ 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
> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>  
>  	  If unsure, say N.
>  
> +config DM_DAX
> +	bool "Direct access (DAX) support"
> +	depends on BLK_DEV_DM
> +	default BLK_DEV_PMEM
> +	select DAX
> +	---help---
> +	  Enable DAX support for the device-mapper linear and stripe
> +	  targets for use with DAX capable block devices like /dev/pmemN.
> +	  If you have a DAX capable block device and have enabled
> +	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
> +
> +	  If unsure, say N.
> +

I'm questioning the need to have yet another Kbuild CONFIG option.  If
the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
be enabled?

Guess I'm just skeptical of: why do we want to move to a model where
users need to opt-in to DM support for DAX?

I also _really_ don't like each target's DAX support being colocated in
drivers/md/dm-dax.c

This all looks and feels like a serious step backwards.

Mike

Re: dm: enable opt-out of device-mapper dax support

[Mike Snitzer]

On Tue, Aug 01 2017 at  2:12pm -0400,
Dan Williams <dan.j.williams@intel.com> wrote:

> Now that dax is no longer a default property of a block-device, i.e.
> ->direct_access() is not a block-device operation, we optionally enable
> device-mapper dax support with a new CONFIG_DM_DAX option.
> 
> All the dax operations helpers are moved to a new file,
> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
> Otherwise, we stub out all the operations with NULL function pointers
> and nop wrappers for the core dax routines.
> 
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/md/Kconfig     |   14 +++
>  drivers/md/Makefile    |    1 
>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>  drivers/md/dm-linear.c |   56 ------------
>  drivers/md/dm-snap.c   |    9 --
>  drivers/md/dm-stripe.c |   89 -------------------
>  drivers/md/dm-target.c |    7 -
>  drivers/md/dm.c        |  105 ++--------------------
>  drivers/md/dm.h        |   34 +++++++
>  10 files changed, 363 insertions(+), 252 deletions(-)
>  create mode 100644 drivers/md/dm-dax.c
>  create mode 100644 drivers/md/dm-dax.h
> 
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 4a249ee86364..bf27b435f7cd 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -200,7 +200,6 @@ 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
> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>  
>  	  If unsure, say N.
>  
> +config DM_DAX
> +	bool "Direct access (DAX) support"
> +	depends on BLK_DEV_DM
> +	default BLK_DEV_PMEM
> +	select DAX
> +	---help---
> +	  Enable DAX support for the device-mapper linear and stripe
> +	  targets for use with DAX capable block devices like /dev/pmemN.
> +	  If you have a DAX capable block device and have enabled
> +	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
> +
> +	  If unsure, say N.
> +

I'm questioning the need to have yet another Kbuild CONFIG option.  If
the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
be enabled?

Guess I'm just skeptical of: why do we want to move to a model where
users need to opt-in to DM support for DAX?

I also _really_ don't like each target's DAX support being colocated in
drivers/md/dm-dax.c

This all looks and feels like a serious step backwards.

Mike

Re: dm: enable opt-out of device-mapper dax support

[Mike Snitzer]

On Tue, Aug 01 2017 at  2:12pm -0400,
Dan Williams <dan.j.williams@intel.com> wrote:

> Now that dax is no longer a default property of a block-device, i.e.
> ->direct_access() is not a block-device operation, we optionally enable
> device-mapper dax support with a new CONFIG_DM_DAX option.
> 
> All the dax operations helpers are moved to a new file,
> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
> Otherwise, we stub out all the operations with NULL function pointers
> and nop wrappers for the core dax routines.
> 
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/md/Kconfig     |   14 +++
>  drivers/md/Makefile    |    1 
>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>  drivers/md/dm-linear.c |   56 ------------
>  drivers/md/dm-snap.c   |    9 --
>  drivers/md/dm-stripe.c |   89 -------------------
>  drivers/md/dm-target.c |    7 -
>  drivers/md/dm.c        |  105 ++--------------------
>  drivers/md/dm.h        |   34 +++++++
>  10 files changed, 363 insertions(+), 252 deletions(-)
>  create mode 100644 drivers/md/dm-dax.c
>  create mode 100644 drivers/md/dm-dax.h
> 
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 4a249ee86364..bf27b435f7cd 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -200,7 +200,6 @@ 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
> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>  
>  	  If unsure, say N.
>  
> +config DM_DAX
> +	bool "Direct access (DAX) support"
> +	depends on BLK_DEV_DM
> +	default BLK_DEV_PMEM
> +	select DAX
> +	---help---
> +	  Enable DAX support for the device-mapper linear and stripe
> +	  targets for use with DAX capable block devices like /dev/pmemN.
> +	  If you have a DAX capable block device and have enabled
> +	  filesystem DAX support (CONFIG_FS_DAX), then say Y.
> +
> +	  If unsure, say N.
> +

I'm questioning the need to have yet another Kbuild CONFIG option.  If
the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
be enabled?

Guess I'm just skeptical of: why do we want to move to a model where
users need to opt-in to DM support for DAX?

I also _really_ don't like each target's DAX support being colocated in
drivers/md/dm-dax.c

This all looks and feels like a serious step backwards.

Mike
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Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Tue, Aug 01 2017 at  2:12pm -0400,
> Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
>
>> Now that dax is no longer a default property of a block-device, i.e.
>> ->direct_access() is not a block-device operation, we optionally enable
>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>
>> All the dax operations helpers are moved to a new file,
>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>> Otherwise, we stub out all the operations with NULL function pointers
>> and nop wrappers for the core dax routines.
>>
>> Cc: Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> Reported-by: Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>
>> Signed-off-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>> ---
>>  drivers/md/Kconfig     |   14 +++
>>  drivers/md/Makefile    |    1
>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>  drivers/md/dm-linear.c |   56 ------------
>>  drivers/md/dm-snap.c   |    9 --
>>  drivers/md/dm-stripe.c |   89 -------------------
>>  drivers/md/dm-target.c |    7 -
>>  drivers/md/dm.c        |  105 ++--------------------
>>  drivers/md/dm.h        |   34 +++++++
>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>  create mode 100644 drivers/md/dm-dax.c
>>  create mode 100644 drivers/md/dm-dax.h
>>
>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>> index 4a249ee86364..bf27b435f7cd 100644
>> --- a/drivers/md/Kconfig
>> +++ b/drivers/md/Kconfig
>> @@ -200,7 +200,6 @@ 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
>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>
>>         If unsure, say N.
>>
>> +config DM_DAX
>> +     bool "Direct access (DAX) support"
>> +     depends on BLK_DEV_DM
>> +     default BLK_DEV_PMEM
>> +     select DAX
>> +     ---help---
>> +       Enable DAX support for the device-mapper linear and stripe
>> +       targets for use with DAX capable block devices like /dev/pmemN.
>> +       If you have a DAX capable block device and have enabled
>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>> +
>> +       If unsure, say N.
>> +
>
> I'm questioning the need to have yet another Kbuild CONFIG option.  If
> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> be enabled?
>
> Guess I'm just skeptical of: why do we want to move to a model where
> users need to opt-in to DM support for DAX?
>
> I also _really_ don't like each target's DAX support being colocated in
> drivers/md/dm-dax.c
>
> This all looks and feels like a serious step backwards.

Ok, you want ifdef'd sections of DAX code in each target and make
DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
else?

Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Tue, Aug 01 2017 at  2:12pm -0400,
> Dan Williams <dan.j.williams@intel.com> wrote:
>
>> Now that dax is no longer a default property of a block-device, i.e.
>> ->direct_access() is not a block-device operation, we optionally enable
>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>
>> All the dax operations helpers are moved to a new file,
>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>> Otherwise, we stub out all the operations with NULL function pointers
>> and nop wrappers for the core dax routines.
>>
>> Cc: Alasdair Kergon <agk@redhat.com>
>> Cc: Mike Snitzer <snitzer@redhat.com>
>> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>> ---
>>  drivers/md/Kconfig     |   14 +++
>>  drivers/md/Makefile    |    1
>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>  drivers/md/dm-linear.c |   56 ------------
>>  drivers/md/dm-snap.c   |    9 --
>>  drivers/md/dm-stripe.c |   89 -------------------
>>  drivers/md/dm-target.c |    7 -
>>  drivers/md/dm.c        |  105 ++--------------------
>>  drivers/md/dm.h        |   34 +++++++
>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>  create mode 100644 drivers/md/dm-dax.c
>>  create mode 100644 drivers/md/dm-dax.h
>>
>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>> index 4a249ee86364..bf27b435f7cd 100644
>> --- a/drivers/md/Kconfig
>> +++ b/drivers/md/Kconfig
>> @@ -200,7 +200,6 @@ 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
>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>
>>         If unsure, say N.
>>
>> +config DM_DAX
>> +     bool "Direct access (DAX) support"
>> +     depends on BLK_DEV_DM
>> +     default BLK_DEV_PMEM
>> +     select DAX
>> +     ---help---
>> +       Enable DAX support for the device-mapper linear and stripe
>> +       targets for use with DAX capable block devices like /dev/pmemN.
>> +       If you have a DAX capable block device and have enabled
>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>> +
>> +       If unsure, say N.
>> +
>
> I'm questioning the need to have yet another Kbuild CONFIG option.  If
> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> be enabled?
>
> Guess I'm just skeptical of: why do we want to move to a model where
> users need to opt-in to DM support for DAX?
>
> I also _really_ don't like each target's DAX support being colocated in
> drivers/md/dm-dax.c
>
> This all looks and feels like a serious step backwards.

Ok, you want ifdef'd sections of DAX code in each target and make
DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
else?

Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Tue, Aug 01 2017 at  2:12pm -0400,
> Dan Williams <dan.j.williams@intel.com> wrote:
>
>> Now that dax is no longer a default property of a block-device, i.e.
>> ->direct_access() is not a block-device operation, we optionally enable
>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>
>> All the dax operations helpers are moved to a new file,
>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>> Otherwise, we stub out all the operations with NULL function pointers
>> and nop wrappers for the core dax routines.
>>
>> Cc: Alasdair Kergon <agk@redhat.com>
>> Cc: Mike Snitzer <snitzer@redhat.com>
>> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>> ---
>>  drivers/md/Kconfig     |   14 +++
>>  drivers/md/Makefile    |    1
>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>  drivers/md/dm-linear.c |   56 ------------
>>  drivers/md/dm-snap.c   |    9 --
>>  drivers/md/dm-stripe.c |   89 -------------------
>>  drivers/md/dm-target.c |    7 -
>>  drivers/md/dm.c        |  105 ++--------------------
>>  drivers/md/dm.h        |   34 +++++++
>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>  create mode 100644 drivers/md/dm-dax.c
>>  create mode 100644 drivers/md/dm-dax.h
>>
>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>> index 4a249ee86364..bf27b435f7cd 100644
>> --- a/drivers/md/Kconfig
>> +++ b/drivers/md/Kconfig
>> @@ -200,7 +200,6 @@ 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
>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>
>>         If unsure, say N.
>>
>> +config DM_DAX
>> +     bool "Direct access (DAX) support"
>> +     depends on BLK_DEV_DM
>> +     default BLK_DEV_PMEM
>> +     select DAX
>> +     ---help---
>> +       Enable DAX support for the device-mapper linear and stripe
>> +       targets for use with DAX capable block devices like /dev/pmemN.
>> +       If you have a DAX capable block device and have enabled
>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>> +
>> +       If unsure, say N.
>> +
>
> I'm questioning the need to have yet another Kbuild CONFIG option.  If
> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> be enabled?
>
> Guess I'm just skeptical of: why do we want to move to a model where
> users need to opt-in to DM support for DAX?
>
> I also _really_ don't like each target's DAX support being colocated in
> drivers/md/dm-dax.c
>
> This all looks and feels like a serious step backwards.

Ok, you want ifdef'd sections of DAX code in each target and make
DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
else?
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Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>> On Tue, Aug 01 2017 at  2:12pm -0400,
>> Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
>>
>>> Now that dax is no longer a default property of a block-device, i.e.
>>> ->direct_access() is not a block-device operation, we optionally enable
>>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>>
>>> All the dax operations helpers are moved to a new file,
>>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>>> Otherwise, we stub out all the operations with NULL function pointers
>>> and nop wrappers for the core dax routines.
>>>
>>> Cc: Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>>> Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>>> Reported-by: Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>
>>> Signed-off-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>>> ---
>>>  drivers/md/Kconfig     |   14 +++
>>>  drivers/md/Makefile    |    1
>>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>>  drivers/md/dm-linear.c |   56 ------------
>>>  drivers/md/dm-snap.c   |    9 --
>>>  drivers/md/dm-stripe.c |   89 -------------------
>>>  drivers/md/dm-target.c |    7 -
>>>  drivers/md/dm.c        |  105 ++--------------------
>>>  drivers/md/dm.h        |   34 +++++++
>>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>>  create mode 100644 drivers/md/dm-dax.c
>>>  create mode 100644 drivers/md/dm-dax.h
>>>
>>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>>> index 4a249ee86364..bf27b435f7cd 100644
>>> --- a/drivers/md/Kconfig
>>> +++ b/drivers/md/Kconfig
>>> @@ -200,7 +200,6 @@ 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
>>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>>
>>>         If unsure, say N.
>>>
>>> +config DM_DAX
>>> +     bool "Direct access (DAX) support"
>>> +     depends on BLK_DEV_DM
>>> +     default BLK_DEV_PMEM
>>> +     select DAX
>>> +     ---help---
>>> +       Enable DAX support for the device-mapper linear and stripe
>>> +       targets for use with DAX capable block devices like /dev/pmemN.
>>> +       If you have a DAX capable block device and have enabled
>>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>>> +
>>> +       If unsure, say N.
>>> +
>>
>> I'm questioning the need to have yet another Kbuild CONFIG option.  If
>> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
>> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
>> be enabled?
>>
>> Guess I'm just skeptical of: why do we want to move to a model where
>> users need to opt-in to DM support for DAX?
>>
>> I also _really_ don't like each target's DAX support being colocated in
>> drivers/md/dm-dax.c
>>
>> This all looks and feels like a serious step backwards.
>
> Ok, you want ifdef'd sections of DAX code in each target and make
> DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> else?

Actually, no, I was thrown off by Bart's suggestion to move code
around. I can handle this all by deleting "select DAX" and adding more
stubbed out dax helpers.

Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
>> On Tue, Aug 01 2017 at  2:12pm -0400,
>> Dan Williams <dan.j.williams@intel.com> wrote:
>>
>>> Now that dax is no longer a default property of a block-device, i.e.
>>> ->direct_access() is not a block-device operation, we optionally enable
>>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>>
>>> All the dax operations helpers are moved to a new file,
>>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>>> Otherwise, we stub out all the operations with NULL function pointers
>>> and nop wrappers for the core dax routines.
>>>
>>> Cc: Alasdair Kergon <agk@redhat.com>
>>> Cc: Mike Snitzer <snitzer@redhat.com>
>>> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
>>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>>> ---
>>>  drivers/md/Kconfig     |   14 +++
>>>  drivers/md/Makefile    |    1
>>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>>  drivers/md/dm-linear.c |   56 ------------
>>>  drivers/md/dm-snap.c   |    9 --
>>>  drivers/md/dm-stripe.c |   89 -------------------
>>>  drivers/md/dm-target.c |    7 -
>>>  drivers/md/dm.c        |  105 ++--------------------
>>>  drivers/md/dm.h        |   34 +++++++
>>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>>  create mode 100644 drivers/md/dm-dax.c
>>>  create mode 100644 drivers/md/dm-dax.h
>>>
>>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>>> index 4a249ee86364..bf27b435f7cd 100644
>>> --- a/drivers/md/Kconfig
>>> +++ b/drivers/md/Kconfig
>>> @@ -200,7 +200,6 @@ 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
>>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>>
>>>         If unsure, say N.
>>>
>>> +config DM_DAX
>>> +     bool "Direct access (DAX) support"
>>> +     depends on BLK_DEV_DM
>>> +     default BLK_DEV_PMEM
>>> +     select DAX
>>> +     ---help---
>>> +       Enable DAX support for the device-mapper linear and stripe
>>> +       targets for use with DAX capable block devices like /dev/pmemN.
>>> +       If you have a DAX capable block device and have enabled
>>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>>> +
>>> +       If unsure, say N.
>>> +
>>
>> I'm questioning the need to have yet another Kbuild CONFIG option.  If
>> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
>> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
>> be enabled?
>>
>> Guess I'm just skeptical of: why do we want to move to a model where
>> users need to opt-in to DM support for DAX?
>>
>> I also _really_ don't like each target's DAX support being colocated in
>> drivers/md/dm-dax.c
>>
>> This all looks and feels like a serious step backwards.
>
> Ok, you want ifdef'd sections of DAX code in each target and make
> DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> else?

Actually, no, I was thrown off by Bart's suggestion to move code
around. I can handle this all by deleting "select DAX" and adding more
stubbed out dax helpers.

Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
>> On Tue, Aug 01 2017 at  2:12pm -0400,
>> Dan Williams <dan.j.williams@intel.com> wrote:
>>
>>> Now that dax is no longer a default property of a block-device, i.e.
>>> ->direct_access() is not a block-device operation, we optionally enable
>>> device-mapper dax support with a new CONFIG_DM_DAX option.
>>>
>>> All the dax operations helpers are moved to a new file,
>>> drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y.
>>> Otherwise, we stub out all the operations with NULL function pointers
>>> and nop wrappers for the core dax routines.
>>>
>>> Cc: Alasdair Kergon <agk@redhat.com>
>>> Cc: Mike Snitzer <snitzer@redhat.com>
>>> Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
>>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>>> ---
>>>  drivers/md/Kconfig     |   14 +++
>>>  drivers/md/Makefile    |    1
>>>  drivers/md/dm-dax.c    |  227 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>  drivers/md/dm-dax.h    |   73 +++++++++++++++
>>>  drivers/md/dm-linear.c |   56 ------------
>>>  drivers/md/dm-snap.c   |    9 --
>>>  drivers/md/dm-stripe.c |   89 -------------------
>>>  drivers/md/dm-target.c |    7 -
>>>  drivers/md/dm.c        |  105 ++--------------------
>>>  drivers/md/dm.h        |   34 +++++++
>>>  10 files changed, 363 insertions(+), 252 deletions(-)
>>>  create mode 100644 drivers/md/dm-dax.c
>>>  create mode 100644 drivers/md/dm-dax.h
>>>
>>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>>> index 4a249ee86364..bf27b435f7cd 100644
>>> --- a/drivers/md/Kconfig
>>> +++ b/drivers/md/Kconfig
>>> @@ -200,7 +200,6 @@ 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
>>> @@ -214,6 +213,19 @@ config BLK_DEV_DM
>>>
>>>         If unsure, say N.
>>>
>>> +config DM_DAX
>>> +     bool "Direct access (DAX) support"
>>> +     depends on BLK_DEV_DM
>>> +     default BLK_DEV_PMEM
>>> +     select DAX
>>> +     ---help---
>>> +       Enable DAX support for the device-mapper linear and stripe
>>> +       targets for use with DAX capable block devices like /dev/pmemN.
>>> +       If you have a DAX capable block device and have enabled
>>> +       filesystem DAX support (CONFIG_FS_DAX), then say Y.
>>> +
>>> +       If unsure, say N.
>>> +
>>
>> I'm questioning the need to have yet another Kbuild CONFIG option.  If
>> the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
>> gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
>> be enabled?
>>
>> Guess I'm just skeptical of: why do we want to move to a model where
>> users need to opt-in to DM support for DAX?
>>
>> I also _really_ don't like each target's DAX support being colocated in
>> drivers/md/dm-dax.c
>>
>> This all looks and feels like a serious step backwards.
>
> Ok, you want ifdef'd sections of DAX code in each target and make
> DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> else?

Actually, no, I was thrown off by Bart's suggestion to move code
around. I can handle this all by deleting "select DAX" and adding more
stubbed out dax helpers.
_______________________________________________
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Re: dm: enable opt-out of device-mapper dax support

[Bart Van Assche]

On Tue, 2017-08-01 at 13:59 -0700, Dan Williams wrote:
> On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> > On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > > On Tue, Aug 01 2017 at  2:12pm -0400,
> > > Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> > > > [ ... ]
> > > 
> > > I'm questioning the need to have yet another Kbuild CONFIG option.  If
> > > the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> > > gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> > > be enabled?
> > > 
> > > Guess I'm just skeptical of: why do we want to move to a model where
> > > users need to opt-in to DM support for DAX?
> > > 
> > > I also _really_ don't like each target's DAX support being colocated in
> > > drivers/md/dm-dax.c
> > > 
> > > This all looks and feels like a serious step backwards.
> > 
> > Ok, you want ifdef'd sections of DAX code in each target and make
> > DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> > else?
> 
> Actually, no, I was thrown off by Bart's suggestion to move code
> around. I can handle this all by deleting "select DAX" and adding more
> stubbed out dax helpers.

Hello Mike and Dan,

How about one *-dax.c file per *.c dm file that has to be modified to add DAX support?
I think that approach would avoid collocation of code for different targets in a
single dm-dax.c file and would also avoid that #ifdef CONFIG_DAX statements have to
be added. This approach is orthogonal to removal of CONFIG_DM_DAX.

Thanks,

Bart.

Re: dm: enable opt-out of device-mapper dax support

[Bart Van Assche]

On Tue, 2017-08-01 at 13:59 -0700, Dan Williams wrote:
> On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> > > On Tue, Aug 01 2017 at  2:12pm -0400,
> > > Dan Williams <dan.j.williams@intel.com> wrote:
> > > > [ ... ]
> > > 
> > > I'm questioning the need to have yet another Kbuild CONFIG option.  If
> > > the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> > > gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> > > be enabled?
> > > 
> > > Guess I'm just skeptical of: why do we want to move to a model where
> > > users need to opt-in to DM support for DAX?
> > > 
> > > I also _really_ don't like each target's DAX support being colocated in
> > > drivers/md/dm-dax.c
> > > 
> > > This all looks and feels like a serious step backwards.
> > 
> > Ok, you want ifdef'd sections of DAX code in each target and make
> > DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> > else?
> 
> Actually, no, I was thrown off by Bart's suggestion to move code
> around. I can handle this all by deleting "select DAX" and adding more
> stubbed out dax helpers.

Hello Mike and Dan,

How about one *-dax.c file per *.c dm file that has to be modified to add DAX support?
I think that approach would avoid collocation of code for different targets in a
single dm-dax.c file and would also avoid that #ifdef CONFIG_DAX statements have to
be added. This approach is orthogonal to removal of CONFIG_DM_DAX.

Thanks,

Bart.

Re: dm: enable opt-out of device-mapper dax support

[Bart Van Assche]

On Tue, 2017-08-01 at 13:59 -0700, Dan Williams wrote:
> On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> > > On Tue, Aug 01 2017 at  2:12pm -0400,
> > > Dan Williams <dan.j.williams@intel.com> wrote:
> > > > [ ... ]
> > > 
> > > I'm questioning the need to have yet another Kbuild CONFIG option.  If
> > > the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
> > > gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
> > > be enabled?
> > > 
> > > Guess I'm just skeptical of: why do we want to move to a model where
> > > users need to opt-in to DM support for DAX?
> > > 
> > > I also _really_ don't like each target's DAX support being colocated in
> > > drivers/md/dm-dax.c
> > > 
> > > This all looks and feels like a serious step backwards.
> > 
> > Ok, you want ifdef'd sections of DAX code in each target and make
> > DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
> > else?
> 
> Actually, no, I was thrown off by Bart's suggestion to move code
> around. I can handle this all by deleting "select DAX" and adding more
> stubbed out dax helpers.

Hello Mike and Dan,

How about one *-dax.c file per *.c dm file that has to be modified to add DAX support?
I think that approach would avoid collocation of code for different targets in a
single dm-dax.c file and would also avoid that #ifdef CONFIG_DAX statements have to
be added. This approach is orthogonal to removal of CONFIG_DM_DAX.

Thanks,

Bart.
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Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 2:04 PM, Bart Van Assche <Bart.VanAssche@wdc.com> wrote:
> On Tue, 2017-08-01 at 13:59 -0700, Dan Williams wrote:
>> On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>> > On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
>> > > On Tue, Aug 01 2017 at  2:12pm -0400,
>> > > Dan Williams <dan.j.williams@intel.com> wrote:
>> > > > [ ... ]
>> > >
>> > > I'm questioning the need to have yet another Kbuild CONFIG option.  If
>> > > the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
>> > > gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
>> > > be enabled?
>> > >
>> > > Guess I'm just skeptical of: why do we want to move to a model where
>> > > users need to opt-in to DM support for DAX?
>> > >
>> > > I also _really_ don't like each target's DAX support being colocated in
>> > > drivers/md/dm-dax.c
>> > >
>> > > This all looks and feels like a serious step backwards.
>> >
>> > Ok, you want ifdef'd sections of DAX code in each target and make
>> > DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
>> > else?
>>
>> Actually, no, I was thrown off by Bart's suggestion to move code
>> around. I can handle this all by deleting "select DAX" and adding more
>> stubbed out dax helpers.
>
> Hello Mike and Dan,
>
> How about one *-dax.c file per *.c dm file that has to be modified to add DAX support?
> I think that approach would avoid collocation of code for different targets in a
> single dm-dax.c file and would also avoid that #ifdef CONFIG_DAX statements have to
> be added. This approach is orthogonal to removal of CONFIG_DM_DAX.

You're free to send an alternative approach, but the new ifdefs in
include/linux/dax.h seem to be the cleanest option to remove dax text
size when the device-mapper dax support is not needed.

Re: dm: enable opt-out of device-mapper dax support

[Dan Williams]

On Tue, Aug 1, 2017 at 2:04 PM, Bart Van Assche <Bart.VanAssche@wdc.com> wrote:
> On Tue, 2017-08-01 at 13:59 -0700, Dan Williams wrote:
>> On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>> > On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@redhat.com> wrote:
>> > > On Tue, Aug 01 2017 at  2:12pm -0400,
>> > > Dan Williams <dan.j.williams@intel.com> wrote:
>> > > > [ ... ]
>> > >
>> > > I'm questioning the need to have yet another Kbuild CONFIG option.  If
>> > > the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already
>> > > gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just
>> > > be enabled?
>> > >
>> > > Guess I'm just skeptical of: why do we want to move to a model where
>> > > users need to opt-in to DM support for DAX?
>> > >
>> > > I also _really_ don't like each target's DAX support being colocated in
>> > > drivers/md/dm-dax.c
>> > >
>> > > This all looks and feels like a serious step backwards.
>> >
>> > Ok, you want ifdef'd sections of DAX code in each target and make
>> > DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything
>> > else?
>>
>> Actually, no, I was thrown off by Bart's suggestion to move code
>> around. I can handle this all by deleting "select DAX" and adding more
>> stubbed out dax helpers.
>
> Hello Mike and Dan,
>
> How about one *-dax.c file per *.c dm file that has to be modified to add DAX support?
> I think that approach would avoid collocation of code for different targets in a
> single dm-dax.c file and would also avoid that #ifdef CONFIG_DAX statements have to
> be added. This approach is orthogonal to removal of CONFIG_DM_DAX.

You're free to send an alternative approach, but the new ifdefs in
include/linux/dax.h seem to be the cleanest option to remove dax text
size when the device-mapper dax support is not needed.
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[PATCH v2] dm: allow device-mapper to operate without dax support

[Dan Williams]

Rather than 'select dax', let the fact that BLK_DEV_PMEM selects dax act
as a gate for the device-mapper dax support. Given that all the dax core
routines compile to nops when CONFIG_DAX=n, we can simply handle the
alloc_dax() error as expected and ifdef out the other dax support code.

Cc: Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Reported-by: Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>
Signed-off-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/md/Kconfig     |    1 -
 drivers/md/dm-linear.c |    6 ++++++
 drivers/md/dm-stripe.c |    6 ++++++
 drivers/md/dm.c        |   10 ++++++----
 include/linux/dax.h    |   19 +++++++++++++++----
 5 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..8ed48ff351cc 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..8804e278e834 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -154,6 +154,7 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -197,6 +198,11 @@ static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#endif
 
 static struct target_type linear_target = {
 	.name   = "linear",
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..eeb6c784dc4f 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -311,6 +311,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -369,6 +370,11 @@ static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#endif
 
 /*
  * Stripe status:
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..70fa48f4d3a3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1713,7 +1713,7 @@ 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 dax_device *dax_dev = NULL;
 	struct mapped_device *md;
 	void *old_md;
 
@@ -1779,9 +1779,11 @@ static struct mapped_device *alloc_dev(int minor)
 	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;
+	if (IS_ENABLED(CONFIG_DAX)) {
+		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);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 794811875732..5d51c5ef678b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -27,16 +27,30 @@ extern struct attribute_group dax_attribute_group;
 
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *dax_get_by_host(const char *host);
+struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops);
 void put_dax(struct dax_device *dax_dev);
+void kill_dax(struct dax_device *dax_dev);
 #else
 static inline struct dax_device *dax_get_by_host(const char *host)
 {
 	return NULL;
 }
-
+static inline struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops)
+{
+	/*
+	 * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
+	 * NULL is an error or expected.
+	 */
+	return NULL;
+}
 static inline void put_dax(struct dax_device *dax_dev)
 {
 }
+static inline void kill_dax(struct dax_device *dax_dev)
+{
+}
 #endif
 
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
@@ -75,10 +89,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 
 int dax_read_lock(void);
 void dax_read_unlock(int id);
-struct dax_device *alloc_dax(void *private, const char *host,
-		const struct dax_operations *ops);
 bool dax_alive(struct dax_device *dax_dev);
-void kill_dax(struct dax_device *dax_dev);
 void *dax_get_private(struct dax_device *dax_dev);
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
 		void **kaddr, pfn_t *pfn);

[PATCH v2] dm: allow device-mapper to operate without dax support

[Dan Williams]

Rather than 'select dax', let the fact that BLK_DEV_PMEM selects dax act
as a gate for the device-mapper dax support. Given that all the dax core
routines compile to nops when CONFIG_DAX=n, we can simply handle the
alloc_dax() error as expected and ifdef out the other dax support code.

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/md/Kconfig     |    1 -
 drivers/md/dm-linear.c |    6 ++++++
 drivers/md/dm-stripe.c |    6 ++++++
 drivers/md/dm.c        |   10 ++++++----
 include/linux/dax.h    |   19 +++++++++++++++----
 5 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..8ed48ff351cc 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..8804e278e834 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -154,6 +154,7 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -197,6 +198,11 @@ static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#endif
 
 static struct target_type linear_target = {
 	.name   = "linear",
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..eeb6c784dc4f 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -311,6 +311,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -369,6 +370,11 @@ static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#endif
 
 /*
  * Stripe status:
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..70fa48f4d3a3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1713,7 +1713,7 @@ 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 dax_device *dax_dev = NULL;
 	struct mapped_device *md;
 	void *old_md;
 
@@ -1779,9 +1779,11 @@ static struct mapped_device *alloc_dev(int minor)
 	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;
+	if (IS_ENABLED(CONFIG_DAX)) {
+		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);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 794811875732..5d51c5ef678b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -27,16 +27,30 @@ extern struct attribute_group dax_attribute_group;
 
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *dax_get_by_host(const char *host);
+struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops);
 void put_dax(struct dax_device *dax_dev);
+void kill_dax(struct dax_device *dax_dev);
 #else
 static inline struct dax_device *dax_get_by_host(const char *host)
 {
 	return NULL;
 }
-
+static inline struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops)
+{
+	/*
+	 * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
+	 * NULL is an error or expected.
+	 */
+	return NULL;
+}
 static inline void put_dax(struct dax_device *dax_dev)
 {
 }
+static inline void kill_dax(struct dax_device *dax_dev)
+{
+}
 #endif
 
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
@@ -75,10 +89,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 
 int dax_read_lock(void);
 void dax_read_unlock(int id);
-struct dax_device *alloc_dax(void *private, const char *host,
-		const struct dax_operations *ops);
 bool dax_alive(struct dax_device *dax_dev);
-void kill_dax(struct dax_device *dax_dev);
 void *dax_get_private(struct dax_device *dax_dev);
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
 		void **kaddr, pfn_t *pfn);

[PATCH v2] dm: allow device-mapper to operate without dax support

[Dan Williams]

Rather than 'select dax', let the fact that BLK_DEV_PMEM selects dax act
as a gate for the device-mapper dax support. Given that all the dax core
routines compile to nops when CONFIG_DAX=n, we can simply handle the
alloc_dax() error as expected and ifdef out the other dax support code.

Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/md/Kconfig     |    1 -
 drivers/md/dm-linear.c |    6 ++++++
 drivers/md/dm-stripe.c |    6 ++++++
 drivers/md/dm.c        |   10 ++++++----
 include/linux/dax.h    |   19 +++++++++++++++----
 5 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..8ed48ff351cc 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,6 @@ 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
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 41971a090e34..8804e278e834 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -154,6 +154,7 @@ static int linear_iterate_devices(struct dm_target *ti,
 	return fn(ti, lc->dev, lc->start, ti->len, data);
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -197,6 +198,11 @@ static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_flush NULL
+#endif
 
 static struct target_type linear_target = {
 	.name   = "linear",
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index a0375530b07f..eeb6c784dc4f 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -311,6 +311,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 	return DM_MAPIO_REMAPPED;
 }
 
+#if IS_ENABLED(CONFIG_DAX)
 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 		long nr_pages, void **kaddr, pfn_t *pfn)
 {
@@ -369,6 +370,11 @@ static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr,
 		return;
 	dax_flush(dax_dev, pgoff, addr, size);
 }
+#else
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#define stripe_dax_flush NULL
+#endif
 
 /*
  * Stripe status:
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2edbcc2d7d3f..70fa48f4d3a3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1713,7 +1713,7 @@ 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 dax_device *dax_dev = NULL;
 	struct mapped_device *md;
 	void *old_md;
 
@@ -1779,9 +1779,11 @@ static struct mapped_device *alloc_dev(int minor)
 	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;
+	if (IS_ENABLED(CONFIG_DAX)) {
+		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);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 794811875732..5d51c5ef678b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -27,16 +27,30 @@ extern struct attribute_group dax_attribute_group;
 
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *dax_get_by_host(const char *host);
+struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops);
 void put_dax(struct dax_device *dax_dev);
+void kill_dax(struct dax_device *dax_dev);
 #else
 static inline struct dax_device *dax_get_by_host(const char *host)
 {
 	return NULL;
 }
-
+static inline struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops)
+{
+	/*
+	 * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
+	 * NULL is an error or expected.
+	 */
+	return NULL;
+}
 static inline void put_dax(struct dax_device *dax_dev)
 {
 }
+static inline void kill_dax(struct dax_device *dax_dev)
+{
+}
 #endif
 
 int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
@@ -75,10 +89,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev)
 
 int dax_read_lock(void);
 void dax_read_unlock(int id);
-struct dax_device *alloc_dax(void *private, const char *host,
-		const struct dax_operations *ops);
 bool dax_alive(struct dax_device *dax_dev);
-void kill_dax(struct dax_device *dax_dev);
 void *dax_get_private(struct dax_device *dax_dev);
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
 		void **kaddr, pfn_t *pfn);

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Re: [PATCH v2] dm: allow device-mapper to operate without dax support

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 14422 bytes --]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-allow-device-mapper-to-operate-without-dax-support/20170802-155255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: s390-defconfig (attached as .config)
compiler: s390x-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=s390 

All errors (new ones prefixed by >>):

   drivers/md/dm.o: In function `cleanup_mapped_device':
>> drivers/md/dm.c:1684: undefined reference to `kill_dax'
>> drivers/md/dm.c:1685: undefined reference to `put_dax'
   drivers/md/dm.o: In function `close_table_device':
   drivers/md/dm.c:651: undefined reference to `put_dax'
   drivers/md/dm.o: In function `open_table_device':
>> drivers/md/dm.c:637: undefined reference to `dax_get_by_host'
   drivers/md/dm.o: In function `dm_dax_flush':
>> drivers/md/dm.c:1003: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `dm_dax_copy_from_iter':
   drivers/md/dm.c:979: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `dm_dax_direct_access':
   drivers/md/dm.c:951: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `alloc_dev':
>> drivers/md/dm.c:1783: undefined reference to `alloc_dax'
   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
   drivers/md/dm-table.c:1644: undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
   drivers/md/dm-table.c:1822: undefined reference to `dax_write_cache'
   drivers/md/dm-linear.o: In function `linear_dax_flush':
>> drivers/md/dm-linear.c:197: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:199: undefined reference to `dax_flush'
   drivers/md/dm-linear.o: In function `linear_dax_copy_from_iter':
   drivers/md/dm-linear.c:183: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:185: undefined reference to `dax_copy_from_iter'
   drivers/md/dm-linear.o: In function `linear_dax_direct_access':
   drivers/md/dm-linear.c:168: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:171: undefined reference to `dax_direct_access'
   drivers/md/dm-stripe.o: In function `stripe_dax_flush':
>> drivers/md/dm-stripe.c:369: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:371: undefined reference to `dax_flush'
   drivers/md/dm-stripe.o: In function `stripe_dax_copy_from_iter':
   drivers/md/dm-stripe.c:350: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:352: undefined reference to `dax_copy_from_iter'
   drivers/md/dm-stripe.o: In function `stripe_dax_direct_access':
   drivers/md/dm-stripe.c:330: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:333: undefined reference to `dax_direct_access'

vim +1684 drivers/md/dm.c

4a0b4ddf2 Mike Snitzer        2010-08-12  1672  
0f20972f7 Mike Snitzer        2015-04-28  1673  static void cleanup_mapped_device(struct mapped_device *md)
0f20972f7 Mike Snitzer        2015-04-28  1674  {
0f20972f7 Mike Snitzer        2015-04-28  1675  	if (md->wq)
0f20972f7 Mike Snitzer        2015-04-28  1676  		destroy_workqueue(md->wq);
0f20972f7 Mike Snitzer        2015-04-28  1677  	if (md->kworker_task)
0f20972f7 Mike Snitzer        2015-04-28  1678  		kthread_stop(md->kworker_task);
0f20972f7 Mike Snitzer        2015-04-28  1679  	mempool_destroy(md->io_pool);
0f20972f7 Mike Snitzer        2015-04-28  1680  	if (md->bs)
0f20972f7 Mike Snitzer        2015-04-28  1681  		bioset_free(md->bs);
0f20972f7 Mike Snitzer        2015-04-28  1682  
f26c5719b Dan Williams        2017-04-12  1683  	if (md->dax_dev) {
f26c5719b Dan Williams        2017-04-12 @1684  		kill_dax(md->dax_dev);
f26c5719b Dan Williams        2017-04-12 @1685  		put_dax(md->dax_dev);
f26c5719b Dan Williams        2017-04-12  1686  		md->dax_dev = NULL;
f26c5719b Dan Williams        2017-04-12  1687  	}
f26c5719b Dan Williams        2017-04-12  1688  
0f20972f7 Mike Snitzer        2015-04-28  1689  	if (md->disk) {
0f20972f7 Mike Snitzer        2015-04-28  1690  		spin_lock(&_minor_lock);
0f20972f7 Mike Snitzer        2015-04-28  1691  		md->disk->private_data = NULL;
0f20972f7 Mike Snitzer        2015-04-28  1692  		spin_unlock(&_minor_lock);
0f20972f7 Mike Snitzer        2015-04-28  1693  		del_gendisk(md->disk);
0f20972f7 Mike Snitzer        2015-04-28  1694  		put_disk(md->disk);
0f20972f7 Mike Snitzer        2015-04-28  1695  	}
0f20972f7 Mike Snitzer        2015-04-28  1696  
0f20972f7 Mike Snitzer        2015-04-28  1697  	if (md->queue)
0f20972f7 Mike Snitzer        2015-04-28  1698  		blk_cleanup_queue(md->queue);
0f20972f7 Mike Snitzer        2015-04-28  1699  
d09960b00 Tahsin Erdogan      2016-10-10  1700  	cleanup_srcu_struct(&md->io_barrier);
d09960b00 Tahsin Erdogan      2016-10-10  1701  
0f20972f7 Mike Snitzer        2015-04-28  1702  	if (md->bdev) {
0f20972f7 Mike Snitzer        2015-04-28  1703  		bdput(md->bdev);
0f20972f7 Mike Snitzer        2015-04-28  1704  		md->bdev = NULL;
0f20972f7 Mike Snitzer        2015-04-28  1705  	}
4cc96131a Mike Snitzer        2016-05-12  1706  
4cc96131a Mike Snitzer        2016-05-12  1707  	dm_mq_cleanup_mapped_device(md);
0f20972f7 Mike Snitzer        2015-04-28  1708  }
0f20972f7 Mike Snitzer        2015-04-28  1709  
^1da177e4 Linus Torvalds      2005-04-16  1710  /*
^1da177e4 Linus Torvalds      2005-04-16  1711   * Allocate and initialise a blank device with a given minor.
^1da177e4 Linus Torvalds      2005-04-16  1712   */
2b06cfff1 Alasdair G Kergon   2006-06-26  1713  static struct mapped_device *alloc_dev(int minor)
^1da177e4 Linus Torvalds      2005-04-16  1714  {
115485e83 Mike Snitzer        2016-02-22  1715  	int r, numa_node_id = dm_get_numa_node();
74f22ed6b Dan Williams        2017-08-01  1716  	struct dax_device *dax_dev = NULL;
115485e83 Mike Snitzer        2016-02-22  1717  	struct mapped_device *md;
ba61fdd17 Jeff Mahoney        2006-06-26  1718  	void *old_md;
^1da177e4 Linus Torvalds      2005-04-16  1719  
115485e83 Mike Snitzer        2016-02-22  1720  	md = kzalloc_node(sizeof(*md), GFP_KERNEL, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1721  	if (!md) {
^1da177e4 Linus Torvalds      2005-04-16  1722  		DMWARN("unable to allocate device, out of memory.");
^1da177e4 Linus Torvalds      2005-04-16  1723  		return NULL;
^1da177e4 Linus Torvalds      2005-04-16  1724  	}
^1da177e4 Linus Torvalds      2005-04-16  1725  
10da4f795 Jeff Mahoney        2006-06-26  1726  	if (!try_module_get(THIS_MODULE))
6ed7ade89 Milan Broz          2008-02-08  1727  		goto bad_module_get;
10da4f795 Jeff Mahoney        2006-06-26  1728  
^1da177e4 Linus Torvalds      2005-04-16  1729  	/* get a minor number for the dev */
2b06cfff1 Alasdair G Kergon   2006-06-26  1730  	if (minor == DM_ANY_MINOR)
cf13ab8e0 Frederik Deweerdt   2008-04-24  1731  		r = next_free_minor(&minor);
2b06cfff1 Alasdair G Kergon   2006-06-26  1732  	else
cf13ab8e0 Frederik Deweerdt   2008-04-24  1733  		r = specific_minor(minor);
^1da177e4 Linus Torvalds      2005-04-16  1734  	if (r < 0)
6ed7ade89 Milan Broz          2008-02-08  1735  		goto bad_minor;
^1da177e4 Linus Torvalds      2005-04-16  1736  
83d5e5b0a Mikulas Patocka     2013-07-10  1737  	r = init_srcu_struct(&md->io_barrier);
83d5e5b0a Mikulas Patocka     2013-07-10  1738  	if (r < 0)
83d5e5b0a Mikulas Patocka     2013-07-10  1739  		goto bad_io_barrier;
83d5e5b0a Mikulas Patocka     2013-07-10  1740  
115485e83 Mike Snitzer        2016-02-22  1741  	md->numa_node_id = numa_node_id;
4cc96131a Mike Snitzer        2016-05-12  1742  	md->use_blk_mq = dm_use_blk_mq_default();
591ddcfc4 Mike Snitzer        2016-01-31  1743  	md->init_tio_pdu = false;
a5664dad7 Mike Snitzer        2010-08-12  1744  	md->type = DM_TYPE_NONE;
e61290a4a Daniel Walker       2008-02-08  1745  	mutex_init(&md->suspend_lock);
a5664dad7 Mike Snitzer        2010-08-12  1746  	mutex_init(&md->type_lock);
86f1152b1 Benjamin Marzinski  2014-08-13  1747  	mutex_init(&md->table_devices_lock);
022c26110 Mikulas Patocka     2009-04-02  1748  	spin_lock_init(&md->deferred_lock);
^1da177e4 Linus Torvalds      2005-04-16  1749  	atomic_set(&md->holders, 1);
5c6bd75d0 Alasdair G Kergon   2006-06-26  1750  	atomic_set(&md->open_count, 0);
^1da177e4 Linus Torvalds      2005-04-16  1751  	atomic_set(&md->event_nr, 0);
7a8c3d3b9 Mike Anderson       2007-10-19  1752  	atomic_set(&md->uevent_seq, 0);
7a8c3d3b9 Mike Anderson       2007-10-19  1753  	INIT_LIST_HEAD(&md->uevent_list);
86f1152b1 Benjamin Marzinski  2014-08-13  1754  	INIT_LIST_HEAD(&md->table_devices);
7a8c3d3b9 Mike Anderson       2007-10-19  1755  	spin_lock_init(&md->uevent_lock);
^1da177e4 Linus Torvalds      2005-04-16  1756  
115485e83 Mike Snitzer        2016-02-22  1757  	md->queue = blk_alloc_queue_node(GFP_KERNEL, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1758  	if (!md->queue)
0f20972f7 Mike Snitzer        2015-04-28  1759  		goto bad;
^1da177e4 Linus Torvalds      2005-04-16  1760  
4a0b4ddf2 Mike Snitzer        2010-08-12  1761  	dm_init_md_queue(md);
9faf400f7 Stefan Bader        2006-10-03  1762  
115485e83 Mike Snitzer        2016-02-22  1763  	md->disk = alloc_disk_node(1, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1764  	if (!md->disk)
0f20972f7 Mike Snitzer        2015-04-28  1765  		goto bad;
^1da177e4 Linus Torvalds      2005-04-16  1766  
316d315bf Nikanth Karthikesan 2009-10-06  1767  	atomic_set(&md->pending[0], 0);
316d315bf Nikanth Karthikesan 2009-10-06  1768  	atomic_set(&md->pending[1], 0);
f0b041153 Jeff Mahoney        2006-06-26  1769  	init_waitqueue_head(&md->wait);
53d5914f2 Mikulas Patocka     2009-04-02  1770  	INIT_WORK(&md->work, dm_wq_work);
f0b041153 Jeff Mahoney        2006-06-26  1771  	init_waitqueue_head(&md->eventq);
2995fa78e Mikulas Patocka     2014-01-13  1772  	init_completion(&md->kobj_holder.completion);
2eb6e1e3a Keith Busch         2014-10-17  1773  	md->kworker_task = NULL;
f0b041153 Jeff Mahoney        2006-06-26  1774  
^1da177e4 Linus Torvalds      2005-04-16  1775  	md->disk->major = _major;
^1da177e4 Linus Torvalds      2005-04-16  1776  	md->disk->first_minor = minor;
^1da177e4 Linus Torvalds      2005-04-16  1777  	md->disk->fops = &dm_blk_dops;
^1da177e4 Linus Torvalds      2005-04-16  1778  	md->disk->queue = md->queue;
^1da177e4 Linus Torvalds      2005-04-16  1779  	md->disk->private_data = md;
^1da177e4 Linus Torvalds      2005-04-16  1780  	sprintf(md->disk->disk_name, "dm-%d", minor);
f26c5719b Dan Williams        2017-04-12  1781  
74f22ed6b Dan Williams        2017-08-01  1782  	if (IS_ENABLED(CONFIG_DAX)) {
f26c5719b Dan Williams        2017-04-12 @1783  		dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
f26c5719b Dan Williams        2017-04-12  1784  		if (!dax_dev)
f26c5719b Dan Williams        2017-04-12  1785  			goto bad;
74f22ed6b Dan Williams        2017-08-01  1786  	}
f26c5719b Dan Williams        2017-04-12  1787  	md->dax_dev = dax_dev;
f26c5719b Dan Williams        2017-04-12  1788  
^1da177e4 Linus Torvalds      2005-04-16  1789  	add_disk(md->disk);
7e51f257e Mike Anderson       2006-03-27  1790  	format_dev_t(md->name, MKDEV(_major, minor));
^1da177e4 Linus Torvalds      2005-04-16  1791  
670368a8d Tejun Heo           2013-07-30  1792  	md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
304f3f6a5 Milan Broz          2008-02-08  1793  	if (!md->wq)
0f20972f7 Mike Snitzer        2015-04-28  1794  		goto bad;
304f3f6a5 Milan Broz          2008-02-08  1795  
32a926da5 Mikulas Patocka     2009-06-22  1796  	md->bdev = bdget_disk(md->disk, 0);
32a926da5 Mikulas Patocka     2009-06-22  1797  	if (!md->bdev)
0f20972f7 Mike Snitzer        2015-04-28  1798  		goto bad;
32a926da5 Mikulas Patocka     2009-06-22  1799  
3a83f4677 Ming Lei            2016-11-22  1800  	bio_init(&md->flush_bio, NULL, 0);
6a8736d10 Tejun Heo           2010-09-08  1801  	md->flush_bio.bi_bdev = md->bdev;
ff0361b34 Jan Kara            2017-05-31  1802  	md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
6a8736d10 Tejun Heo           2010-09-08  1803  
fd2ed4d25 Mikulas Patocka     2013-08-16  1804  	dm_stats_init(&md->stats);
fd2ed4d25 Mikulas Patocka     2013-08-16  1805  
ba61fdd17 Jeff Mahoney        2006-06-26  1806  	/* Populate the mapping, nobody knows we exist yet */
f32c10b09 Jeff Mahoney        2006-06-26  1807  	spin_lock(&_minor_lock);
ba61fdd17 Jeff Mahoney        2006-06-26  1808  	old_md = idr_replace(&_minor_idr, md, minor);
f32c10b09 Jeff Mahoney        2006-06-26  1809  	spin_unlock(&_minor_lock);
ba61fdd17 Jeff Mahoney        2006-06-26  1810  
ba61fdd17 Jeff Mahoney        2006-06-26  1811  	BUG_ON(old_md != MINOR_ALLOCED);
ba61fdd17 Jeff Mahoney        2006-06-26  1812  
^1da177e4 Linus Torvalds      2005-04-16  1813  	return md;
^1da177e4 Linus Torvalds      2005-04-16  1814  
0f20972f7 Mike Snitzer        2015-04-28  1815  bad:
0f20972f7 Mike Snitzer        2015-04-28  1816  	cleanup_mapped_device(md);
83d5e5b0a Mikulas Patocka     2013-07-10  1817  bad_io_barrier:
^1da177e4 Linus Torvalds      2005-04-16  1818  	free_minor(minor);
6ed7ade89 Milan Broz          2008-02-08  1819  bad_minor:
10da4f795 Jeff Mahoney        2006-06-26  1820  	module_put(THIS_MODULE);
6ed7ade89 Milan Broz          2008-02-08  1821  bad_module_get:
^1da177e4 Linus Torvalds      2005-04-16  1822  	kfree(md);
^1da177e4 Linus Torvalds      2005-04-16  1823  	return NULL;
^1da177e4 Linus Torvalds      2005-04-16  1824  }
^1da177e4 Linus Torvalds      2005-04-16  1825  

:::::: The code at line 1684 was first introduced by commit
:::::: f26c5719b2d7b00de69eb83eb1c1c831759fdc9b dm: add dax_device and dax_operations support

:::::: TO: Dan Williams <dan.j.williams@intel.com>
:::::: CC: Dan Williams <dan.j.williams@intel.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 10958 bytes --]

Re: [PATCH v2] dm: allow device-mapper to operate without dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-allow-device-mapper-to-operate-without-dax-support/20170802-155255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: s390-defconfig (attached as .config)
compiler: s390x-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=s390 

All errors (new ones prefixed by >>):

   drivers/md/dm.o: In function `cleanup_mapped_device':
>> drivers/md/dm.c:1684: undefined reference to `kill_dax'
>> drivers/md/dm.c:1685: undefined reference to `put_dax'
   drivers/md/dm.o: In function `close_table_device':
   drivers/md/dm.c:651: undefined reference to `put_dax'
   drivers/md/dm.o: In function `open_table_device':
>> drivers/md/dm.c:637: undefined reference to `dax_get_by_host'
   drivers/md/dm.o: In function `dm_dax_flush':
>> drivers/md/dm.c:1003: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `dm_dax_copy_from_iter':
   drivers/md/dm.c:979: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `dm_dax_direct_access':
   drivers/md/dm.c:951: undefined reference to `dax_get_private'
   drivers/md/dm.o: In function `alloc_dev':
>> drivers/md/dm.c:1783: undefined reference to `alloc_dax'
   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
   drivers/md/dm-table.c:1644: undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
   drivers/md/dm-table.c:1822: undefined reference to `dax_write_cache'
   drivers/md/dm-linear.o: In function `linear_dax_flush':
>> drivers/md/dm-linear.c:197: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:199: undefined reference to `dax_flush'
   drivers/md/dm-linear.o: In function `linear_dax_copy_from_iter':
   drivers/md/dm-linear.c:183: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:185: undefined reference to `dax_copy_from_iter'
   drivers/md/dm-linear.o: In function `linear_dax_direct_access':
   drivers/md/dm-linear.c:168: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-linear.c:171: undefined reference to `dax_direct_access'
   drivers/md/dm-stripe.o: In function `stripe_dax_flush':
>> drivers/md/dm-stripe.c:369: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:371: undefined reference to `dax_flush'
   drivers/md/dm-stripe.o: In function `stripe_dax_copy_from_iter':
   drivers/md/dm-stripe.c:350: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:352: undefined reference to `dax_copy_from_iter'
   drivers/md/dm-stripe.o: In function `stripe_dax_direct_access':
   drivers/md/dm-stripe.c:330: undefined reference to `bdev_dax_pgoff'
>> drivers/md/dm-stripe.c:333: undefined reference to `dax_direct_access'

vim +1684 drivers/md/dm.c

4a0b4ddf2 Mike Snitzer        2010-08-12  1672  
0f20972f7 Mike Snitzer        2015-04-28  1673  static void cleanup_mapped_device(struct mapped_device *md)
0f20972f7 Mike Snitzer        2015-04-28  1674  {
0f20972f7 Mike Snitzer        2015-04-28  1675  	if (md->wq)
0f20972f7 Mike Snitzer        2015-04-28  1676  		destroy_workqueue(md->wq);
0f20972f7 Mike Snitzer        2015-04-28  1677  	if (md->kworker_task)
0f20972f7 Mike Snitzer        2015-04-28  1678  		kthread_stop(md->kworker_task);
0f20972f7 Mike Snitzer        2015-04-28  1679  	mempool_destroy(md->io_pool);
0f20972f7 Mike Snitzer        2015-04-28  1680  	if (md->bs)
0f20972f7 Mike Snitzer        2015-04-28  1681  		bioset_free(md->bs);
0f20972f7 Mike Snitzer        2015-04-28  1682  
f26c5719b Dan Williams        2017-04-12  1683  	if (md->dax_dev) {
f26c5719b Dan Williams        2017-04-12 @1684  		kill_dax(md->dax_dev);
f26c5719b Dan Williams        2017-04-12 @1685  		put_dax(md->dax_dev);
f26c5719b Dan Williams        2017-04-12  1686  		md->dax_dev = NULL;
f26c5719b Dan Williams        2017-04-12  1687  	}
f26c5719b Dan Williams        2017-04-12  1688  
0f20972f7 Mike Snitzer        2015-04-28  1689  	if (md->disk) {
0f20972f7 Mike Snitzer        2015-04-28  1690  		spin_lock(&_minor_lock);
0f20972f7 Mike Snitzer        2015-04-28  1691  		md->disk->private_data = NULL;
0f20972f7 Mike Snitzer        2015-04-28  1692  		spin_unlock(&_minor_lock);
0f20972f7 Mike Snitzer        2015-04-28  1693  		del_gendisk(md->disk);
0f20972f7 Mike Snitzer        2015-04-28  1694  		put_disk(md->disk);
0f20972f7 Mike Snitzer        2015-04-28  1695  	}
0f20972f7 Mike Snitzer        2015-04-28  1696  
0f20972f7 Mike Snitzer        2015-04-28  1697  	if (md->queue)
0f20972f7 Mike Snitzer        2015-04-28  1698  		blk_cleanup_queue(md->queue);
0f20972f7 Mike Snitzer        2015-04-28  1699  
d09960b00 Tahsin Erdogan      2016-10-10  1700  	cleanup_srcu_struct(&md->io_barrier);
d09960b00 Tahsin Erdogan      2016-10-10  1701  
0f20972f7 Mike Snitzer        2015-04-28  1702  	if (md->bdev) {
0f20972f7 Mike Snitzer        2015-04-28  1703  		bdput(md->bdev);
0f20972f7 Mike Snitzer        2015-04-28  1704  		md->bdev = NULL;
0f20972f7 Mike Snitzer        2015-04-28  1705  	}
4cc96131a Mike Snitzer        2016-05-12  1706  
4cc96131a Mike Snitzer        2016-05-12  1707  	dm_mq_cleanup_mapped_device(md);
0f20972f7 Mike Snitzer        2015-04-28  1708  }
0f20972f7 Mike Snitzer        2015-04-28  1709  
^1da177e4 Linus Torvalds      2005-04-16  1710  /*
^1da177e4 Linus Torvalds      2005-04-16  1711   * Allocate and initialise a blank device with a given minor.
^1da177e4 Linus Torvalds      2005-04-16  1712   */
2b06cfff1 Alasdair G Kergon   2006-06-26  1713  static struct mapped_device *alloc_dev(int minor)
^1da177e4 Linus Torvalds      2005-04-16  1714  {
115485e83 Mike Snitzer        2016-02-22  1715  	int r, numa_node_id = dm_get_numa_node();
74f22ed6b Dan Williams        2017-08-01  1716  	struct dax_device *dax_dev = NULL;
115485e83 Mike Snitzer        2016-02-22  1717  	struct mapped_device *md;
ba61fdd17 Jeff Mahoney        2006-06-26  1718  	void *old_md;
^1da177e4 Linus Torvalds      2005-04-16  1719  
115485e83 Mike Snitzer        2016-02-22  1720  	md = kzalloc_node(sizeof(*md), GFP_KERNEL, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1721  	if (!md) {
^1da177e4 Linus Torvalds      2005-04-16  1722  		DMWARN("unable to allocate device, out of memory.");
^1da177e4 Linus Torvalds      2005-04-16  1723  		return NULL;
^1da177e4 Linus Torvalds      2005-04-16  1724  	}
^1da177e4 Linus Torvalds      2005-04-16  1725  
10da4f795 Jeff Mahoney        2006-06-26  1726  	if (!try_module_get(THIS_MODULE))
6ed7ade89 Milan Broz          2008-02-08  1727  		goto bad_module_get;
10da4f795 Jeff Mahoney        2006-06-26  1728  
^1da177e4 Linus Torvalds      2005-04-16  1729  	/* get a minor number for the dev */
2b06cfff1 Alasdair G Kergon   2006-06-26  1730  	if (minor == DM_ANY_MINOR)
cf13ab8e0 Frederik Deweerdt   2008-04-24  1731  		r = next_free_minor(&minor);
2b06cfff1 Alasdair G Kergon   2006-06-26  1732  	else
cf13ab8e0 Frederik Deweerdt   2008-04-24  1733  		r = specific_minor(minor);
^1da177e4 Linus Torvalds      2005-04-16  1734  	if (r < 0)
6ed7ade89 Milan Broz          2008-02-08  1735  		goto bad_minor;
^1da177e4 Linus Torvalds      2005-04-16  1736  
83d5e5b0a Mikulas Patocka     2013-07-10  1737  	r = init_srcu_struct(&md->io_barrier);
83d5e5b0a Mikulas Patocka     2013-07-10  1738  	if (r < 0)
83d5e5b0a Mikulas Patocka     2013-07-10  1739  		goto bad_io_barrier;
83d5e5b0a Mikulas Patocka     2013-07-10  1740  
115485e83 Mike Snitzer        2016-02-22  1741  	md->numa_node_id = numa_node_id;
4cc96131a Mike Snitzer        2016-05-12  1742  	md->use_blk_mq = dm_use_blk_mq_default();
591ddcfc4 Mike Snitzer        2016-01-31  1743  	md->init_tio_pdu = false;
a5664dad7 Mike Snitzer        2010-08-12  1744  	md->type = DM_TYPE_NONE;
e61290a4a Daniel Walker       2008-02-08  1745  	mutex_init(&md->suspend_lock);
a5664dad7 Mike Snitzer        2010-08-12  1746  	mutex_init(&md->type_lock);
86f1152b1 Benjamin Marzinski  2014-08-13  1747  	mutex_init(&md->table_devices_lock);
022c26110 Mikulas Patocka     2009-04-02  1748  	spin_lock_init(&md->deferred_lock);
^1da177e4 Linus Torvalds      2005-04-16  1749  	atomic_set(&md->holders, 1);
5c6bd75d0 Alasdair G Kergon   2006-06-26  1750  	atomic_set(&md->open_count, 0);
^1da177e4 Linus Torvalds      2005-04-16  1751  	atomic_set(&md->event_nr, 0);
7a8c3d3b9 Mike Anderson       2007-10-19  1752  	atomic_set(&md->uevent_seq, 0);
7a8c3d3b9 Mike Anderson       2007-10-19  1753  	INIT_LIST_HEAD(&md->uevent_list);
86f1152b1 Benjamin Marzinski  2014-08-13  1754  	INIT_LIST_HEAD(&md->table_devices);
7a8c3d3b9 Mike Anderson       2007-10-19  1755  	spin_lock_init(&md->uevent_lock);
^1da177e4 Linus Torvalds      2005-04-16  1756  
115485e83 Mike Snitzer        2016-02-22  1757  	md->queue = blk_alloc_queue_node(GFP_KERNEL, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1758  	if (!md->queue)
0f20972f7 Mike Snitzer        2015-04-28  1759  		goto bad;
^1da177e4 Linus Torvalds      2005-04-16  1760  
4a0b4ddf2 Mike Snitzer        2010-08-12  1761  	dm_init_md_queue(md);
9faf400f7 Stefan Bader        2006-10-03  1762  
115485e83 Mike Snitzer        2016-02-22  1763  	md->disk = alloc_disk_node(1, numa_node_id);
^1da177e4 Linus Torvalds      2005-04-16  1764  	if (!md->disk)
0f20972f7 Mike Snitzer        2015-04-28  1765  		goto bad;
^1da177e4 Linus Torvalds      2005-04-16  1766  
316d315bf Nikanth Karthikesan 2009-10-06  1767  	atomic_set(&md->pending[0], 0);
316d315bf Nikanth Karthikesan 2009-10-06  1768  	atomic_set(&md->pending[1], 0);
f0b041153 Jeff Mahoney        2006-06-26  1769  	init_waitqueue_head(&md->wait);
53d5914f2 Mikulas Patocka     2009-04-02  1770  	INIT_WORK(&md->work, dm_wq_work);
f0b041153 Jeff Mahoney        2006-06-26  1771  	init_waitqueue_head(&md->eventq);
2995fa78e Mikulas Patocka     2014-01-13  1772  	init_completion(&md->kobj_holder.completion);
2eb6e1e3a Keith Busch         2014-10-17  1773  	md->kworker_task = NULL;
f0b041153 Jeff Mahoney        2006-06-26  1774  
^1da177e4 Linus Torvalds      2005-04-16  1775  	md->disk->major = _major;
^1da177e4 Linus Torvalds      2005-04-16  1776  	md->disk->first_minor = minor;
^1da177e4 Linus Torvalds      2005-04-16  1777  	md->disk->fops = &dm_blk_dops;
^1da177e4 Linus Torvalds      2005-04-16  1778  	md->disk->queue = md->queue;
^1da177e4 Linus Torvalds      2005-04-16  1779  	md->disk->private_data = md;
^1da177e4 Linus Torvalds      2005-04-16  1780  	sprintf(md->disk->disk_name, "dm-%d", minor);
f26c5719b Dan Williams        2017-04-12  1781  
74f22ed6b Dan Williams        2017-08-01  1782  	if (IS_ENABLED(CONFIG_DAX)) {
f26c5719b Dan Williams        2017-04-12 @1783  		dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
f26c5719b Dan Williams        2017-04-12  1784  		if (!dax_dev)
f26c5719b Dan Williams        2017-04-12  1785  			goto bad;
74f22ed6b Dan Williams        2017-08-01  1786  	}
f26c5719b Dan Williams        2017-04-12  1787  	md->dax_dev = dax_dev;
f26c5719b Dan Williams        2017-04-12  1788  
^1da177e4 Linus Torvalds      2005-04-16  1789  	add_disk(md->disk);
7e51f257e Mike Anderson       2006-03-27  1790  	format_dev_t(md->name, MKDEV(_major, minor));
^1da177e4 Linus Torvalds      2005-04-16  1791  
670368a8d Tejun Heo           2013-07-30  1792  	md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
304f3f6a5 Milan Broz          2008-02-08  1793  	if (!md->wq)
0f20972f7 Mike Snitzer        2015-04-28  1794  		goto bad;
304f3f6a5 Milan Broz          2008-02-08  1795  
32a926da5 Mikulas Patocka     2009-06-22  1796  	md->bdev = bdget_disk(md->disk, 0);
32a926da5 Mikulas Patocka     2009-06-22  1797  	if (!md->bdev)
0f20972f7 Mike Snitzer        2015-04-28  1798  		goto bad;
32a926da5 Mikulas Patocka     2009-06-22  1799  
3a83f4677 Ming Lei            2016-11-22  1800  	bio_init(&md->flush_bio, NULL, 0);
6a8736d10 Tejun Heo           2010-09-08  1801  	md->flush_bio.bi_bdev = md->bdev;
ff0361b34 Jan Kara            2017-05-31  1802  	md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
6a8736d10 Tejun Heo           2010-09-08  1803  
fd2ed4d25 Mikulas Patocka     2013-08-16  1804  	dm_stats_init(&md->stats);
fd2ed4d25 Mikulas Patocka     2013-08-16  1805  
ba61fdd17 Jeff Mahoney        2006-06-26  1806  	/* Populate the mapping, nobody knows we exist yet */
f32c10b09 Jeff Mahoney        2006-06-26  1807  	spin_lock(&_minor_lock);
ba61fdd17 Jeff Mahoney        2006-06-26  1808  	old_md = idr_replace(&_minor_idr, md, minor);
f32c10b09 Jeff Mahoney        2006-06-26  1809  	spin_unlock(&_minor_lock);
ba61fdd17 Jeff Mahoney        2006-06-26  1810  
ba61fdd17 Jeff Mahoney        2006-06-26  1811  	BUG_ON(old_md != MINOR_ALLOCED);
ba61fdd17 Jeff Mahoney        2006-06-26  1812  
^1da177e4 Linus Torvalds      2005-04-16  1813  	return md;
^1da177e4 Linus Torvalds      2005-04-16  1814  
0f20972f7 Mike Snitzer        2015-04-28  1815  bad:
0f20972f7 Mike Snitzer        2015-04-28  1816  	cleanup_mapped_device(md);
83d5e5b0a Mikulas Patocka     2013-07-10  1817  bad_io_barrier:
^1da177e4 Linus Torvalds      2005-04-16  1818  	free_minor(minor);
6ed7ade89 Milan Broz          2008-02-08  1819  bad_minor:
10da4f795 Jeff Mahoney        2006-06-26  1820  	module_put(THIS_MODULE);
6ed7ade89 Milan Broz          2008-02-08  1821  bad_module_get:
^1da177e4 Linus Torvalds      2005-04-16  1822  	kfree(md);
^1da177e4 Linus Torvalds      2005-04-16  1823  	return NULL;
^1da177e4 Linus Torvalds      2005-04-16  1824  }
^1da177e4 Linus Torvalds      2005-04-16  1825  

:::::: The code at line 1684 was first introduced by commit
:::::: f26c5719b2d7b00de69eb83eb1c1c831759fdc9b dm: add dax_device and dax_operations support

:::::: TO: Dan Williams <dan.j.williams@intel.com>
:::::: CC: Dan Williams <dan.j.williams@intel.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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Re: [PATCH v2] dm: allow device-mapper to operate without dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-allow-device-mapper-to-operate-without-dax-support/20170802-155255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sh-sdk7786_defconfig (attached as .config)
compiler: sh4-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sh 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
   dm-table.c:(.text+0xab4): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> (.text+0x23d0): undefined reference to `dax_write_cache'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCH v2] dm: allow device-mapper to operate without dax support

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1247 bytes --]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-allow-device-mapper-to-operate-without-dax-support/20170802-155255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sh-sdk7786_defconfig (attached as .config)
compiler: sh4-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sh 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
   dm-table.c:(.text+0xab4): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> (.text+0x23d0): undefined reference to `dax_write_cache'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 18571 bytes --]

Re: [PATCH v2] dm: allow device-mapper to operate without dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-allow-device-mapper-to-operate-without-dax-support/20170802-155255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sh-sdk7786_defconfig (attached as .config)
compiler: sh4-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sh 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
   dm-table.c:(.text+0xab4): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> (.text+0x23d0): undefined reference to `dax_write_cache'

---
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_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
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Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sparc64-defconfig (attached as .config)
compiler: sparc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sparc64 

All errors (new ones prefixed by >>):

>> ERROR: "dax_write_cache" [drivers/md/dm-mod.ko] undefined!
>> ERROR: "dax_write_cache_enabled" [drivers/md/dm-mod.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1101 bytes --]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sparc64-defconfig (attached as .config)
compiler: sparc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sparc64 

All errors (new ones prefixed by >>):

>> ERROR: "dax_write_cache" [drivers/md/dm-mod.ko] undefined!
>> ERROR: "dax_write_cache_enabled" [drivers/md/dm-mod.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 17828 bytes --]

Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: sparc64-defconfig (attached as .config)
compiler: sparc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sparc64 

All errors (new ones prefixed by >>):

>> ERROR: "dax_write_cache" [drivers/md/dm-mod.ko] undefined!
>> ERROR: "dax_write_cache_enabled" [drivers/md/dm-mod.ko] undefined!

---
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_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: x86_64-allyesdebian (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
>> dm-table.c:(.text+0x568): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> dm-table.c:(.text+0x1e40): undefined reference to `dax_write_cache'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1096 bytes --]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: x86_64-allyesdebian (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
>> dm-table.c:(.text+0x568): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> dm-table.c:(.text+0x1e40): undefined reference to `dax_write_cache'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 39258 bytes --]

Re: [PATCH] dm: enable opt-out of device-mapper dax support

[kbuild test robot]

Hi Dan,

[auto build test ERROR on dm/for-next]
[also build test ERROR on v4.13-rc3 next-20170801]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/dm-enable-opt-out-of-device-mapper-dax-support/20170802-063827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git for-next
config: x86_64-allyesdebian (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/md/dm-table.o: In function `device_dax_write_cache_enabled':
>> dm-table.c:(.text+0x568): undefined reference to `dax_write_cache_enabled'
   drivers/md/dm-table.o: In function `dm_table_set_restrictions':
>> dm-table.c:(.text+0x1e40): undefined reference to `dax_write_cache'

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0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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