Commit a41fe02b authored by Dan Williams's avatar Dan Williams
Browse files

Revert "block: use DAX for partition table reads" 



commit d1a5f2b4 ("block: use DAX for partition table reads") was
part of a stalled effort to allow dax mappings of block devices. Since
then the device-dax mechanism has filled the role of dax-mapping static
device ranges.

Now that we are moving ->direct_access() from a block_device operation
to a dax_inode operation we would need block devices to map and carry
their own dax_inode reference.

Unless / until we decide to revive dax mapping of raw block devices
through the dax_inode scheme, there is no need to carry
read_dax_sector(). Its removal in turn allows for the removal of
bdev_direct_access() and should have been included in commit
22375701 ("block_dev: remove DAX leftovers").

Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent fa5d932c

block/partition-generic.c

+2 −15
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 
#include <linux/kmod.h>

#include <linux/ctype.h>

#include <linux/genhd.h>

#include <linux/dax.h>

#include <linux/blktrace_api.h>



#include "partitions/check.h"
@@ -631,24 +630,12 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev) 
	return 0;

}



static struct page *read_pagecache_sector(struct block_device *bdev, sector_t n)

{

	struct address_space *mapping = bdev->bd_inode->i_mapping;



	return read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)),

				 NULL);

}



unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)

{

	struct address_space *mapping = bdev->bd_inode->i_mapping;

	struct page *page;



	/* don't populate page cache for dax capable devices */

	if (IS_DAX(bdev->bd_inode))

		page = read_dax_sector(bdev, n);

	else

		page = read_pagecache_sector(bdev, n);



	page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), NULL);

	if (!IS_ERR(page)) {

		if (PageError(page))

			goto fail;

fs/dax.c

+0 −20
Original line number Diff line number Diff line
@@ -101,26 +101,6 @@ static int dax_is_empty_entry(void *entry) 
	return (unsigned long)entry & RADIX_DAX_EMPTY;

}



struct page *read_dax_sector(struct block_device *bdev, sector_t n)

{

	struct page *page = alloc_pages(GFP_KERNEL, 0);

	struct blk_dax_ctl dax = {

		.size = PAGE_SIZE,

		.sector = n & ~((((int) PAGE_SIZE) / 512) - 1),

	};

	long rc;



	if (!page)

		return ERR_PTR(-ENOMEM);



	rc = dax_map_atomic(bdev, &dax);

	if (rc < 0)

		return ERR_PTR(rc);

	memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE);

	dax_unmap_atomic(bdev, &dax);

	return page;

}



/*

 * DAX radix tree locking

 */

include/linux/dax.h

+0 −6
Original line number Diff line number Diff line
@@ -70,15 +70,9 @@ void dax_wake_mapping_entry_waiter(struct address_space *mapping, 
		pgoff_t index, void *entry, bool wake_all);



#ifdef CONFIG_FS_DAX

struct page *read_dax_sector(struct block_device *bdev, sector_t n);

int __dax_zero_page_range(struct block_device *bdev, sector_t sector,

		unsigned int offset, unsigned int length);

#else

static inline struct page *read_dax_sector(struct block_device *bdev,

		sector_t n)

{

	return ERR_PTR(-ENXIO);

}

static inline int __dax_zero_page_range(struct block_device *bdev,

		sector_t sector, unsigned int offset, unsigned int length)

{

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