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Commit a5eb62e3 authored by Miguel's avatar Miguel Committed by Chris Mason
Browse files

Btrfs: Endianess bug fix for v0.13 with kernels 



Fix for a endianess BUG when using btrfs v0.13 with kernels older than 2.6.23

Problem:

Has of v0.13, btrfs-progs is using crc32c.c equivalent to the one found on
linux-2.6.23/lib/libcrc32c.c Since crc32c_le() changed in linux-2.6.23, when
running btrfs v0.13 with older kernels we have a missmatch between the versions
of crc32c_le() from btrfs-progs and libcrc32c in the kernel.  This missmatch
causes a bug when using btrfs on big endian machines.

Solution:
btrfs_crc32c() macro that when compiling for kernels older than 2.6.23, does
endianess conversion to parameters and return value of crc32c().
This endianess conversion nullifies the differences in implementation
of crc32c_le().
If kernel 2.6.23 or better, it calls crc32c().

Signed-off-by: default avatarMiguel Sousa Filipe <miguel.filipe@gmail.com>
---

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 587f7704

fs/btrfs/crc32c.h

0 → 100644
+17 −0
Original line number Diff line number Diff line 
#include <asm/byteorder.h>

#include <linux/crc32c.h>

#include <linux/version.h>



/**

 * implementation of crc32c_le() changed in linux-2.6.23,

 * has of v0.13 btrfs-progs is using the latest version.

 * We must workaround older implementations of crc32c_le()

 * found on older kernel versions.

 */

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)

#define btrfs_crc32c(seed, data, length) \

	__cpu_to_le32( crc32c( __le32_to_cpu(seed), data, length) )

#else

#define btrfs_crc32c(seed, data, length) \

	crc32c(seed, data, length)

#endif

fs/btrfs/disk-io.c

+2 −2
Original line number Diff line number Diff line
@@ -18,13 +18,13 @@ 


#include <linux/fs.h>

#include <linux/blkdev.h>

#include <linux/crc32c.h>

#include <linux/scatterlist.h>

#include <linux/swap.h>

#include <linux/radix-tree.h>

#include <linux/writeback.h>

#include <linux/buffer_head.h> // for block_sync_page

#include <linux/workqueue.h>

#include "crc32c.h"

#include "ctree.h"

#include "disk-io.h"

#include "transaction.h"
@@ -100,7 +100,7 @@ out: 


u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len)

{

	return crc32c(seed, data, len);

	return btrfs_crc32c(seed, data, len);

}



void btrfs_csum_final(u32 crc, char *result)

fs/btrfs/extent-tree.c

+5 −7
Original line number Diff line number Diff line
@@ -15,11 +15,10 @@ 
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 021110-1307, USA.

 */



#include <linux/sched.h>

#include <linux/crc32c.h>

#include <linux/pagemap.h>

#include "hash.h"

#include "crc32c.h"

#include "ctree.h"

#include "disk-io.h"

#include "print-tree.h"
@@ -398,16 +397,15 @@ static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation, 
	u32 high_crc = ~(u32)0;

	u32 low_crc = ~(u32)0;

	__le64 lenum;



	lenum = cpu_to_le64(root_objectid);

	high_crc = crc32c(high_crc, &lenum, sizeof(lenum));

	high_crc = btrfs_crc32c(high_crc, &lenum, sizeof(lenum));

	lenum = cpu_to_le64(ref_generation);

	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));

	low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));

	if (owner >= BTRFS_FIRST_FREE_OBJECTID) {

		lenum = cpu_to_le64(owner);

		low_crc = crc32c(low_crc, &lenum, sizeof(lenum));

		low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));

		lenum = cpu_to_le64(owner_offset);

		low_crc = crc32c(low_crc, &lenum, sizeof(lenum));

		low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));

	}

	return ((u64)high_crc << 32) | (u64)low_crc;

}