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Revision 03cdadb04077b9311bbc67d98cc5401aff76482d authored by Dan Williams on 26 February 2016, 23:19:43 UTC, committed by Linus Torvalds on 27 February 2016, 18:28:52 UTC 
block: disable block device DAX by default
 
The recent *sync enabling discovered that we are inserting into the
block_device pagecache counter to the expectations of the dirty data
tracking for dax mappings.  This can lead to data corruption.

We want to support DAX for block devices eventually, but it requires
wider changes to properly manage the pagecache.

   dump_stack+0x85/0xc2
   dax_writeback_mapping_range+0x60/0xe0
   blkdev_writepages+0x3f/0x50
   do_writepages+0x21/0x30
   __filemap_fdatawrite_range+0xc6/0x100
   filemap_write_and_wait+0x4a/0xa0
   set_blocksize+0x70/0xd0
   sb_set_blocksize+0x1d/0x50
   ext4_fill_super+0x75b/0x3360
   mount_bdev+0x180/0x1b0
   ext4_mount+0x15/0x20
   mount_fs+0x38/0x170

Mark the support broken so its disabled by default, but otherwise still
available for testing.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent a4a8481
Raw File
xz_stream.h 
/*
 * Definitions for handling the .xz file format
 *
 * Author: Lasse Collin <lasse.collin@tukaani.org>
 *
 * This file has been put into the public domain.
 * You can do whatever you want with this file.
 */

#ifndef XZ_STREAM_H
#define XZ_STREAM_H

#if defined(__KERNEL__) && !XZ_INTERNAL_CRC32
#	include <linux/crc32.h>
#	undef crc32
#	define xz_crc32(buf, size, crc) \
		(~crc32_le(~(uint32_t)(crc), buf, size))
#endif

/*
 * See the .xz file format specification at
 * http://tukaani.org/xz/xz-file-format.txt
 * to understand the container format.
 */

#define STREAM_HEADER_SIZE 12

#define HEADER_MAGIC "\3757zXZ"
#define HEADER_MAGIC_SIZE 6

#define FOOTER_MAGIC "YZ"
#define FOOTER_MAGIC_SIZE 2

/*
 * Variable-length integer can hold a 63-bit unsigned integer or a special
 * value indicating that the value is unknown.
 *
 * Experimental: vli_type can be defined to uint32_t to save a few bytes
 * in code size (no effect on speed). Doing so limits the uncompressed and
 * compressed size of the file to less than 256 MiB and may also weaken
 * error detection slightly.
 */
typedef uint64_t vli_type;

#define VLI_MAX ((vli_type)-1 / 2)
#define VLI_UNKNOWN ((vli_type)-1)

/* Maximum encoded size of a VLI */
#define VLI_BYTES_MAX (sizeof(vli_type) * 8 / 7)

/* Integrity Check types */
enum xz_check {
	XZ_CHECK_NONE = 0,
	XZ_CHECK_CRC32 = 1,
	XZ_CHECK_CRC64 = 4,
	XZ_CHECK_SHA256 = 10
};

/* Maximum possible Check ID */
#define XZ_CHECK_MAX 15

#endif
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