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Btrfs: Endianess bug fix for v0.13 with kernels

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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: Miguel Sousa Filipe <miguel.filipe@gmail.com>
---

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Miguel
2008-04-11 15:45:51 -04:00
committed by Chris Mason
parent 587f77043a
commit a5eb62e345
3 changed files with 24 additions and 9 deletions
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17
fs/btrfs/crc32c.h Normal file
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@@ -0,0 +1,17 @@
#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