Provide a replacement for bdev_direct_access() that uses
dax_operations.direct_access() instead of
block_device_operations.direct_access(). Once all consumers of the old
api have been converted bdev_direct_access() will be deleted.
Given that block device partitioning decisions can cause dax page
alignment constraints to be violated we still need to validate the
block_device before calling the dax ->direct_access method.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
block/Kconfig | 1 +
drivers/dax/super.c | 33 +++++++++++++++++++++++++++++++++
fs/block_dev.c | 28 ++++++++++++++++++++++++++++
include/linux/blkdev.h | 3 +++
include/linux/dax.h | 2 ++
5 files changed, 67 insertions(+)
diff --git a/block/Kconfig b/block/Kconfig
index 8bf114a3858a..9be785173280 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -6,6 +6,7 @@ menuconfig BLOCK
default y
select SBITMAP
select SRCU
+ select DAX
help
Provide block layer support for the kernel.
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index eb844ffea3cf..ab5b082df5dd 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -65,6 +65,39 @@ struct dax_inode {
const struct dax_operations *ops;
};
+long dax_direct_access(struct dax_inode *dax_inode, phys_addr_t dev_addr,
+ void **kaddr, pfn_t *pfn, long size)
+{
+ long avail;
+
+ /*
+ * The device driver is allowed to sleep, in order to make the
+ * memory directly accessible.
+ */
+ might_sleep();
+
+ if (!dax_inode)
+ return -EOPNOTSUPP;
+
+ if (!dax_inode_alive(dax_inode))
+ return -ENXIO;
+
+ if (size < 0)
+ return size;
+
+ if (dev_addr % PAGE_SIZE)
+ return -EINVAL;
+
+ avail = dax_inode->ops->direct_access(dax_inode, dev_addr, kaddr, pfn,
+ size);
+ if (!avail)
+ return -ERANGE;
+ if (avail > 0 && avail & ~PAGE_MASK)
+ return -ENXIO;
+ return min(avail, size);
+}
+EXPORT_SYMBOL_GPL(dax_direct_access);
+
bool dax_inode_alive(struct dax_inode *dax_inode)
{
lockdep_assert_held(&dax_srcu);
diff --git a/fs/block_dev.c b/fs/block_dev.c
index edb1d2b16b8f..bf4b51a3a412 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -18,6 +18,7 @@
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/magic.h>
+#include <linux/dax.h>
#include <linux/buffer_head.h>
#include <linux/swap.h>
#include <linux/pagevec.h>
@@ -763,6 +764,33 @@ long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
EXPORT_SYMBOL_GPL(bdev_direct_access);
/**
+ * bdev_dax_direct_access() - bdev-sector to pfn_t and kernel virtual address
+ * @bdev: host block device for @dax_inode
+ * @dax_inode: interface data and operations for a memory device
+ * @dax: control and output parameters for ->direct_access
+ *
+ * Return: negative errno if an error occurs, otherwise the number of bytes
+ * accessible at this address.
+ *
+ * Locking: must be called with dax_read_lock() held
+ */
+long bdev_dax_direct_access(struct block_device *bdev,
+ struct dax_inode *dax_inode, struct blk_dax_ctl *dax)
+{
+ sector_t sector = dax->sector;
+
+ if (!blk_queue_dax(bdev->bd_queue))
+ return -EOPNOTSUPP;
+ if ((sector + DIV_ROUND_UP(dax->size, 512))
+ > part_nr_sects_read(bdev->bd_part))
+ return -ERANGE;
+ sector += get_start_sect(bdev);
+ return dax_direct_access(dax_inode, sector * 512, &dax->addr,
+ &dax->pfn, dax->size);
+}
+EXPORT_SYMBOL_GPL(bdev_dax_direct_access);
+
+/**
* bdev_dax_supported() - Check if the device supports dax for filesystem
* @sb: The superblock of the device
* @blocksize: The block size of the device
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5e7706f7d533..3b3c5ce376fd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1903,6 +1903,9 @@ extern int bdev_read_page(struct block_device *, sector_t, struct page *);
extern int bdev_write_page(struct block_device *, sector_t, struct page *,
struct writeback_control *);
extern long bdev_direct_access(struct block_device *, struct blk_dax_ctl *);
+struct dax_inode;
+extern long bdev_dax_direct_access(struct block_device *bdev,
+ struct dax_inode *dax_inode, struct blk_dax_ctl *dax);
extern int bdev_dax_supported(struct super_block *, int);
#else /* CONFIG_BLOCK */
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 5aa620e8e5a2..2ef8e18e2587 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -22,6 +22,8 @@ void *dax_inode_get_private(struct dax_inode *dax_inode);
void put_dax_inode(struct dax_inode *dax_inode);
bool dax_inode_alive(struct dax_inode *dax_inode);
void kill_dax_inode(struct dax_inode *dax_inode);
+long dax_direct_access(struct dax_inode *dax_inode, phys_addr_t dev_addr,
+ void **kaddr, pfn_t *pfn, long size);
/*
* We use lowest available bit in exceptional entry for locking, one bit for
--
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