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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>
This commit is contained in:
Dan Williams 2017-05-08 10:55:27 -07:00
parent 74d71a01ab
commit ef51042472
9 changed files with 102 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
block/Kconfig
View File

@ -6,7 +6,6 @@ menuconfig BLOCK
default y
select SBITMAP
select SRCU
select DAX
help
Provide block layer support for the kernel.

70
drivers/dax/super.c
View File

@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/magic.h>
#include <linux/genhd.h>
#include <linux/cdev.h>
#include <linux/hash.h>
#include <linux/slab.h>
@ -47,6 +48,75 @@ void dax_read_unlock(int id)
}
EXPORT_SYMBOL_GPL(dax_read_unlock);
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) {
pr_err("VFS (%s): error: unsupported blocksize for dax\n",
sb->s_id);
return -EINVAL;
}
err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
if (err) {
pr_err("VFS (%s): error: unaligned partition for dax\n",
sb->s_id);
return err;
}
dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
if (!dax_dev) {
pr_err("VFS (%s): error: device does not support dax\n",
sb->s_id);
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) {
pr_err("VFS (%s): error: dax access failed (%ld)",
sb->s_id, len);
return len < 0 ? len : -EIO;
}
return 0;
}
EXPORT_SYMBOL_GPL(__bdev_dax_supported);
/**
* struct dax_device - anchor object for dax services
* @inode: core vfs

1
fs/Kconfig
View File

@ -39,6 +39,7 @@ config FS_DAX
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,

66
fs/block_dev.c
View File

@ -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
*/

1
fs/ext2/super.c
View File

@ -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"

1
fs/ext4/super.c
View File

@ -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>

1
fs/xfs/xfs_super.c
View File

@ -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>

2
include/linux/blkdev.h
View File

@ -1940,8 +1940,6 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
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 int bdev_dax_supported(struct super_block *, int);
int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
#else /* CONFIG_BLOCK */
struct block_device;

30
include/linux/dax.h
View File

@ -18,12 +18,38 @@ struct dax_operations {
void **, pfn_t *);
};
int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
#if IS_ENABLED(CONFIG_FS_DAX)
int __bdev_dax_supported(struct super_block *sb, int blocksize);
static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
{
return __bdev_dax_supported(sb, blocksize);
}
#else
static inline int bdev_dax_supported(struct super_block *sb, int blocksize)
{
return -EOPNOTSUPP;
}
#endif
#if IS_ENABLED(CONFIG_DAX)
struct dax_device *dax_get_by_host(const char *host);
void put_dax(struct dax_device *dax_dev);
#else
static inline struct dax_device *dax_get_by_host(const char *host)
{
return NULL;
}
static inline void put_dax(struct dax_device *dax_dev)
{
}
#endif
int dax_read_lock(void);
void dax_read_unlock(int id);
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);
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);