[PATCH 09/17] btrfs: add common checksum type validation

[Johannes Thumshirn <jthumshirn@suse.de>]

Currently btrfs is only supporting CRC32C as checksumming algorithm. As
this is about to change provide a function to validate the checksum type in
the superblock against all possible algorithms.

This makes adding new algorithms easier as there are fewer places to adjust
when adding new algorithms.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 fs/btrfs/disk-io.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 663efce22d98..ab13282d91d2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -356,6 +356,16 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
 	return ret;
 }
 
+static bool btrfs_supported_super_csum(struct btrfs_super_block *sb)
+{
+	switch (btrfs_super_csum_type(sb)) {
+	case BTRFS_CSUM_TYPE_CRC32:
+		return true;
+	default:
+		return false;
+	}
+}
+
 /*
  * Return 0 if the superblock checksum type matches the checksum value of that
  * algorithm. Pass the raw disk superblock data.
@@ -368,6 +378,12 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
 	u16 csum_type = btrfs_super_csum_type(disk_sb);
 	int ret = 0;
 
+	if (!btrfs_supported_super_csum(disk_sb)) {
+		btrfs_err(fs_info, "unsupported checksum algorithm %u",
+			  csum_type);
+		ret = 1;
+	}
+
 	if (csum_type == BTRFS_CSUM_TYPE_CRC32) {
 		u32 crc = ~(u32)0;
 		char result[sizeof(crc)];
@@ -385,12 +401,6 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
 			ret = 1;
 	}
 
-	if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {
-		btrfs_err(fs_info, "unsupported checksum algorithm %u",
-				csum_type);
-		ret = 1;
-	}
-
 	return ret;
 }
 
@@ -2577,7 +2587,7 @@ static int btrfs_validate_write_super(struct btrfs_fs_info *fs_info,
 	ret = validate_super(fs_info, sb, -1);
 	if (ret < 0)
 		goto out;
-	if (btrfs_super_csum_type(sb) != BTRFS_CSUM_TYPE_CRC32) {
+	if (!btrfs_supported_super_csum(sb)) {
 		ret = -EUCLEAN;
 		btrfs_err(fs_info, "invalid csum type, has %u want %u",
 			  btrfs_super_csum_type(sb), BTRFS_CSUM_TYPE_CRC32);
-- 
2.16.4