[PATCH 02/17] bcache: use a separate data structure for the on-disk super block

colyli
2020-01-23T17:01:27Z

From: Christoph Hellwig <hch@lst.de>

Split out an on-disk version struct cache_sb with the proper endianness
annotations. This fixes a fair chunk of sparse warnings, but there are
some left due to the way the checksum is defined.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/bcache/super.c | 6 +++---
include/uapi/linux/bcache.h | 51 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index a573ce1d85aa..3045f27e0d67 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -63,14 +63,14 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
struct page **res)
{
const char *err;
- struct cache_sb *s;
+ struct cache_sb_disk *s;
struct buffer_head *bh = __bread(bdev, 1, SB_SIZE);
unsigned int i;

if (!bh)
return "IO error";

- s = (struct cache_sb *) bh->b_data;
+ s = (struct cache_sb_disk *)bh->b_data;

sb->offset = le64_to_cpu(s->offset);
sb->version = le64_to_cpu(s->version);
@@ -209,7 +209,7 @@ static void write_bdev_super_endio(struct bio *bio)

static void __write_super(struct cache_sb *sb, struct bio *bio)
{
- struct cache_sb *out = page_address(bio_first_page_all(bio));
+ struct cache_sb_disk *out = page_address(bio_first_page_all(bio));
unsigned int i;

bio->bi_iter.bi_sector = SB_SECTOR;
diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h
index 5d4f58e059fd..1d8b3a9fc080 100644
--- a/include/uapi/linux/bcache.h
+++ b/include/uapi/linux/bcache.h
@@ -156,6 +156,57 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)

#define BDEV_DATA_START_DEFAULT 16 /* sectors */

+struct cache_sb_disk {
+ __le64 csum;
+ __le64 offset; /* sector where this sb was written */
+ __le64 version;
+
+ __u8 magic[16];
+
+ __u8 uuid[16];
+ union {
+ __u8 set_uuid[16];
+ __le64 set_magic;
+ };
+ __u8 label[SB_LABEL_SIZE];
+
+ __le64 flags;
+ __le64 seq;
+ __le64 pad[8];
+
+ union {
+ struct {
+ /* Cache devices */
+ __le64 nbuckets; /* device size */
+
+ __le16 block_size; /* sectors */
+ __le16 bucket_size; /* sectors */
+
+ __le16 nr_in_set;
+ __le16 nr_this_dev;
+ };
+ struct {
+ /* Backing devices */
+ __le64 data_offset;
+
+ /*
+ * block_size from the cache device section is still used by
+ * backing devices, so don't add anything here until we fix
+ * things to not need it for backing devices anymore
+ */
+ };
+ };
+
+ __le32 last_mount; /* time overflow in y2106 */
+
+ __le16 first_bucket;
+ union {
+ __le16 njournal_buckets;
+ __le16 keys;
+ };
+ __le64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
+};
+
struct cache_sb {
__u64 csum;
__u64 offset; /* sector where this sb was written */
--
2.16.4