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block: use DAX for partition table reads

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Avoid populating pagecache when the block device is in DAX mode.
Otherwise these page cache entries collide with the fsync/msync
implementation and break data durability guarantees.

Cc: Jan Kara <jack@suse.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2016-01-28 20:25:31 -08:00
parent 9f4736fe7c
commit d1a5f2b4d8
3 changed files with 46 additions and 3 deletions
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18
block/partition-generic.c
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@@ -16,6 +16,7 @@
#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"
@@ -550,13 +551,24 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
return 0;
}
unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
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_CACHE_SHIFT-9)),
NULL);
}
unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
{
struct page *page;
page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
NULL);
/* 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);
if (!IS_ERR(page)) {
if (PageError(page))
goto fail;