[v4,13/13] btrfs: add sha256 as another checksum algorithm

Commit Message

Johannes Thumshirn June 3, 2019, 2:58 p.m. UTC

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 <[e-mail]>

---
changes to v2:
- Add pre dependency on sha256
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
---
 fs/btrfs/Kconfig                | 1 +
 fs/btrfs/btrfs_inode.h          | 1 +
 fs/btrfs/ctree.h                | 4 ++--
 fs/btrfs/disk-io.c              | 1 +
 fs/btrfs/super.c                | 1 +
 include/uapi/linux/btrfs_tree.h | 6 ++++--
 6 files changed, 10 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 212b4a854f2c..2521a24f74be 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -4,6 +4,7 @@  config BTRFS_FS
 	tristate "Btrfs filesystem support"
 	select CRYPTO
 	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 7a89f73b13e6..812efa5e0ff8 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -340,6 +340,7 @@  static inline void btrfs_inode_resume_unlocked_dio(struct btrfs_inode *inode)
 #define CSUM_FORMAT "0x%*phN"
 #define CSUM_FORMAT_VALUE(size, bytes)  size, bytes
 
+
 static inline void btrfs_print_data_csum_error(struct btrfs_inode *inode,
 		u64 logical_start, u8 *csum, u8 *csum_expected, int mirror_num)
 {
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8b635ca370f5..f2246aa2596a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -72,8 +72,8 @@  struct btrfs_ref;
 #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 fc47a682f862..387f959cb45b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -357,6 +357,7 @@  static bool btrfs_supported_super_csum(u16 csum_type)
 {
 	switch (csum_type) {
 	case BTRFS_CSUM_TYPE_CRC32:
+	case BTRFS_CSUM_TYPE_SHA256:
 		return true;
 	default:
 		return false;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f40516ca5963..5d3687354fc7 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2466,3 +2466,4 @@  module_exit(exit_btrfs_fs)
 
 MODULE_LICENSE("GPL");
 MODULE_SOFTDEP("pre: crc32c");
+MODULE_SOFTDEP("pre: sha256");
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 421239b98db2..8edb624410cb 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
  *