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: Miguel Sousa Filipe <miguel.filipe@gmail.com>
---
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/crc32c.h b/fs/btrfs/crc32c.h
new file mode 100644
index 0000000..a93255b
--- /dev/null
+++ b/fs/btrfs/crc32c.h
@@ -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
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e22960e2..0bfcc31 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -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 @@
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)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 283b08a..a056a2d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -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 @@
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;
}