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[resend PATCH v2 04/33] dax: introduce dax_operations

From Dan Williams <dan.j.williams@intel.com>
Newsgroups linux.kernel
Subject [resend PATCH v2 04/33] dax: introduce dax_operations
Date 2017-04-17 21:20 +0200
Message-ID <txklS-4zD-61@gated-at.bofh.it> (permalink)
References <txklP-4zD-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Track a set of dax_operations per dax_device that can be set at
alloc_dax() time. These operations will be used to stop the abuse of
block_device_operations for communicating dax capabilities to
filesystems. It will also be used to replace the "pmem api" and move
pmem-specific cache maintenance, and other dax-driver-specific
filesystem-dax operations, to dax device methods. In particular this
allows us to stop abusing __copy_user_nocache(), via memcpy_to_pmem(),
with a driver specific replacement.

This is a standalone introduction of the operations. Follow on patches
convert each dax-driver and teach fs/dax.c to use ->direct_access() from
dax_operations instead of block_device_operations.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/dax/dax.h    |    4 +++-
 drivers/dax/device.c |    6 +++++-
 drivers/dax/super.c  |    6 +++++-
 include/linux/dax.h  |   10 ++++++++++
 4 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/dax/dax.h b/drivers/dax/dax.h
index 246a24d68d4c..617bbc24be2b 100644
--- a/drivers/dax/dax.h
+++ b/drivers/dax/dax.h
@@ -13,7 +13,9 @@
 #ifndef __DAX_H__
 #define __DAX_H__
 struct dax_device;
-struct dax_device *alloc_dax(void *private, const char *host);
+struct dax_operations;
+struct dax_device *alloc_dax(void *private, const char *host,
+		const struct dax_operations *ops);
 void put_dax(struct dax_device *dax_dev);
 bool dax_alive(struct dax_device *dax_dev);
 void kill_dax(struct dax_device *dax_dev);
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index db68f4fa8ce0..a0db055054a4 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -645,7 +645,11 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 		goto err_id;
 	}
 
-	dax_dev = alloc_dax(dev_dax, NULL);
+	/*
+	 * No 'host' or dax_operations since there is no access to this
+	 * device outside of mmap of the resulting character device.
+	 */
+	dax_dev = alloc_dax(dev_dax, NULL, NULL);
 	if (!dax_dev)
 		goto err_dax;
 
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index bb22956a106b..45ccfc043da8 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -17,6 +17,7 @@
 #include <linux/cdev.h>
 #include <linux/hash.h>
 #include <linux/slab.h>
+#include <linux/dax.h>
 #include <linux/fs.h>
 
 static int nr_dax = CONFIG_NR_DEV_DAX;
@@ -61,6 +62,7 @@ struct dax_device {
 	const char *host;
 	void *private;
 	bool alive;
+	const struct dax_operations *ops;
 };
 
 bool dax_alive(struct dax_device *dax_dev)
@@ -204,7 +206,8 @@ static void dax_add_host(struct dax_device *dax_dev, const char *host)
 	spin_unlock(&dax_host_lock);
 }
 
-struct dax_device *alloc_dax(void *private, const char *__host)
+struct dax_device *alloc_dax(void *private, const char *__host,
+		const struct dax_operations *ops)
 {
 	struct dax_device *dax_dev;
 	const char *host;
@@ -225,6 +228,7 @@ struct dax_device *alloc_dax(void *private, const char *__host)
 		goto err_dev;
 
 	dax_add_host(dax_dev, host);
+	dax_dev->ops = ops;
 	dax_dev->private = private;
 	return dax_dev;
 
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9b2d5ba10d7d..74ebb92b625a 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -7,6 +7,16 @@
 #include <asm/pgtable.h>
 
 struct iomap_ops;
+struct dax_device;
+struct dax_operations {
+	/*
+	 * direct_access: translate a device-relative
+	 * logical-page-offset into an absolute physical pfn. Return the
+	 * number of pages available for DAX at that pfn.
+	 */
+	long (*direct_access)(struct dax_device *, pgoff_t, long,
+			void **, pfn_t *);
+};
 
 int dax_read_lock(void);
 void dax_read_unlock(int id);

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Thread

[resend PATCH v2 00/33] dax: introduce dax_operations Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 32/33] filesystem-dax: gate calls to dax_flush()  on QUEUE_FLAG_WC Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 03/33] dax: add a facility to lookup a dax device  by 'host' device name Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 22/33] dax,  pmem: introduce an optional 'flush' dax_operation Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 02/33] dax: refactor dax-fs into a generic  provider of 'struct dax_device' instances Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 15/33] filesystem-dax: convert to  dax_direct_access() Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 06/33] axon_ram: add dax_operations support Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 17/33] block: remove block_device_operations  ->direct_access() Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 13/33] ext2, ext4,  xfs: retrieve dax_device for iomap operations Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 04/33] dax: introduce dax_operations Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 20/33] dm: add ->copy_from_iter() dax operation  support Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 27/33] x86, libnvdimm,  pmem: move arch_invalidate_pmem() to libnvdimm Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 05/33] pmem: add dax_operations support Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:20 +0200
  [resend PATCH v2 12/33] dm: teach dm-targets to use a dax_device +  dax_operations Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  [resend PATCH v2 18/33] x86, dax,  pmem: remove indirection around memcpy_from_pmem() Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  [resend PATCH v2 07/33] brd: add dax_operations support Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  [resend PATCH v2 24/33] filesystem-dax: convert to dax_flush() Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  [resend PATCH v2 14/33] Revert "block: use DAX for partition table  reads" Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  [resend PATCH v2 01/33] device-dax: rename 'dax_dev' to 'dev_dax' Dan Williams <dan.j.williams@intel.com> - 2017-04-17 21:30 +0200
  Re: [resend PATCH v2 00/33] dax: introduce dax_operations Dan Williams <dan.j.williams@intel.com> - 2017-04-22 03:10 +0200

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