block, dax: move "select DAX" from BLOCK to FS_DAX
For configurations that do not enable DAX filesystems or drivers, do not
require the DAX core to be built.
Given that the 'direct_access' method has been removed from
'block_device_operations', we can also go ahead and remove the
block-related dax helper functions from fs/block_dev.c to
drivers/dax/super.c. This keeps dax details out of the block layer and
lets the DAX core be built as a module in the FS_DAX=n case.
Filesystems need to include dax.h to call bdev_dax_supported().
Cc: linux-xfs@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/fs/Kconfig b/fs/Kconfig
index 83eab52..b0e42b6 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -39,6 +39,7 @@
depends on MMU
depends on !(ARM || MIPS || SPARC)
select FS_IOMAP
+ select DAX
help
Direct Access (DAX) can be used on memory-backed block devices.
If the block device supports DAX and the filesystem supports DAX,
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 666367e..3096ecd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -718,72 +718,6 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL_GPL(bdev_write_page);
-int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
- pgoff_t *pgoff)
-{
- phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512;
-
- if (pgoff)
- *pgoff = PHYS_PFN(phys_off);
- if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
- return -EINVAL;
- return 0;
-}
-EXPORT_SYMBOL(bdev_dax_pgoff);
-
-/**
- * bdev_dax_supported() - Check if the device supports dax for filesystem
- * @sb: The superblock of the device
- * @blocksize: The block size of the device
- *
- * This is a library function for filesystems to check if the block device
- * can be mounted with dax option.
- *
- * Return: negative errno if unsupported, 0 if supported.
- */
-int bdev_dax_supported(struct super_block *sb, int blocksize)
-{
- struct block_device *bdev = sb->s_bdev;
- struct dax_device *dax_dev;
- pgoff_t pgoff;
- int err, id;
- void *kaddr;
- pfn_t pfn;
- long len;
-
- if (blocksize != PAGE_SIZE) {
- vfs_msg(sb, KERN_ERR, "error: unsupported blocksize for dax");
- return -EINVAL;
- }
-
- err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
- if (err) {
- vfs_msg(sb, KERN_ERR, "error: unaligned partition for dax");
- return err;
- }
-
- dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
- if (!dax_dev) {
- vfs_msg(sb, KERN_ERR, "error: device does not support dax");
- return -EOPNOTSUPP;
- }
-
- id = dax_read_lock();
- len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
- dax_read_unlock(id);
-
- put_dax(dax_dev);
-
- if (len < 1) {
- vfs_msg(sb, KERN_ERR,
- "error: dax access failed (%ld)", len);
- return len < 0 ? len : -EIO;
- }
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(bdev_dax_supported);
-
/*
* pseudo-fs
*/
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 9e25a71..d07773b 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -32,6 +32,7 @@
#include <linux/log2.h>
#include <linux/quotaops.h>
#include <linux/uaccess.h>
+#include <linux/dax.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a9448db..bf6bb89 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -37,6 +37,7 @@
#include <linux/ctype.h>
#include <linux/log2.h>
#include <linux/crc16.h>
+#include <linux/dax.h>
#include <linux/cleancache.h>
#include <linux/uaccess.h>
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 685c042..f5c58d6 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -52,6 +52,7 @@
#include "xfs_reflink.h"
#include <linux/namei.h>
+#include <linux/dax.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mount.h>