btrfs: add sha256 as another checksum algorithm
Now that we everything in place, we can add SHA-256 as another checksum
algorithm.
SHA-256 was taken as it was the cryptographically strongest algorithm that
can fit into the 32 Bytes we have left.
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
---
Changes to v1:
- Select SHA-256 in KConfig
- Minimalize switch() in btrfs_supported_super_csum() (Nikolay)
- Use enum for new on-disk checksum type (Nikolay/David)
- Format SHA256 using sprintf()'s hexdump mode
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 8f48c3b..64f793b 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -3,6 +3,7 @@
config BTRFS_FS
tristate "Btrfs filesystem support"
select CRYPTO_CRC32C
+ select CRYPTO_SHA256
select ZLIB_INFLATE
select ZLIB_DEFLATE
select LZO_COMPRESS
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index e79fd91..125bc7f 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -346,6 +346,9 @@
case BTRFS_CSUM_TYPE_CRC32:
snprintf(cbuf, size, "0x%08x", *(u32 *)csum);
break;
+ case BTRFS_CSUM_TYPE_SHA256:
+ snprintf(cbuf, size, "%*phN", (int)size / 8, csum);
+ break;
default: /* can't happen - csum type is validated at mount time */
break;
}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0624057..83d4cb2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -72,8 +72,8 @@
#define BTRFS_LINK_MAX 65535U
/* four bytes for CRC32 */
-static const int btrfs_csum_sizes[] = { 4 };
-static char *btrfs_csum_names[] = { "crc32c" };
+static const int btrfs_csum_sizes[] = { 4, 32 };
+static char *btrfs_csum_names[] = { "crc32c", "sha256" };
#define BTRFS_EMPTY_DIR_SIZE 0
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7368a6e..8d3ba8f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -357,6 +357,7 @@
{
switch (btrfs_super_csum_type(sb)) {
case BTRFS_CSUM_TYPE_CRC32:
+ case BTRFS_CSUM_TYPE_SHA256:
return true;
default:
return false;
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 421239b..8edb624 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -300,8 +300,10 @@
#define BTRFS_CSUM_SIZE 32
/* csum types */
-#define BTRFS_CSUM_TYPE_CRC32 0
-
+enum {
+ BTRFS_CSUM_TYPE_CRC32 = 0,
+ BTRFS_CSUM_TYPE_SHA256 = 1,
+};
/*
* flags definitions for directory entry item type
*
