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bcache: Take data offset from the bdev superblock.
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Add a new superblock version, and consolidate related defines.

Signed-off-by: Gabriel de Perthuis <g2p.code+bcache@gmail.com>
Signed-off-by: Kent Overstreet <koverstreet@google.com>
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Kent Overstreet committed Apr 21, 2013
1 parent cef5279 commit 2903381
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Showing 3 changed files with 100 additions and 57 deletions.
47 changes: 37 additions & 10 deletions drivers/md/bcache/bcache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -223,11 +223,17 @@ struct bkey {
#define BKEY_PADDED(key) \
union { struct bkey key; uint64_t key ## _pad[BKEY_PAD]; }

/* Version 1: Backing device
/* Version 0: Cache device
* Version 1: Backing device
* Version 2: Seed pointer into btree node checksum
* Version 3: New UUID format
* Version 3: Cache device with new UUID format
* Version 4: Backing device with data offset
*/
#define BCACHE_SB_VERSION 3
#define BCACHE_SB_VERSION_CDEV 0
#define BCACHE_SB_VERSION_BDEV 1
#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
#define BCACHE_SB_MAX_VERSION 4

#define SB_SECTOR 8
#define SB_SIZE 4096
Expand All @@ -236,13 +242,12 @@ struct bkey {
/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
#define MAX_CACHES_PER_SET 8

#define BDEV_DATA_START 16 /* sectors */
#define BDEV_DATA_START_DEFAULT 16 /* sectors */

struct cache_sb {
uint64_t csum;
uint64_t offset; /* sector where this sb was written */
uint64_t version;
#define CACHE_BACKING_DEV 1

uint8_t magic[16];

Expand All @@ -257,12 +262,28 @@ struct cache_sb {
uint64_t seq;
uint64_t pad[8];

uint64_t nbuckets; /* device size */
uint16_t block_size; /* sectors */
uint16_t bucket_size; /* sectors */
union {
struct {
/* Cache devices */
uint64_t nbuckets; /* device size */

uint16_t block_size; /* sectors */
uint16_t bucket_size; /* sectors */

uint16_t nr_in_set;
uint16_t nr_this_dev;
uint16_t nr_in_set;
uint16_t nr_this_dev;
};
struct {
/* Backing devices */
uint64_t 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
*/
};
};

uint32_t last_mount; /* time_t */

Expand Down Expand Up @@ -861,6 +882,12 @@ static inline bool key_merging_disabled(struct cache_set *c)
#endif
}

static inline bool SB_IS_BDEV(const struct cache_sb *sb)
{
return sb->version == BCACHE_SB_VERSION_BDEV
|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
}

struct bbio {
unsigned submit_time_us;
union {
Expand Down
2 changes: 1 addition & 1 deletion drivers/md/bcache/request.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1220,7 +1220,7 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
part_stat_unlock();

bio->bi_bdev = dc->bdev;
bio->bi_sector += BDEV_DATA_START;
bio->bi_sector += dc->sb.data_offset;

if (cached_dev_get(dc)) {
s = search_alloc(bio, d);
Expand Down
108 changes: 62 additions & 46 deletions drivers/md/bcache/super.c
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Original file line number Diff line number Diff line change
Expand Up @@ -110,15 +110,7 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,

sb->flags = le64_to_cpu(s->flags);
sb->seq = le64_to_cpu(s->seq);

sb->nbuckets = le64_to_cpu(s->nbuckets);
sb->block_size = le16_to_cpu(s->block_size);
sb->bucket_size = le16_to_cpu(s->bucket_size);

sb->nr_in_set = le16_to_cpu(s->nr_in_set);
sb->nr_this_dev = le16_to_cpu(s->nr_this_dev);
sb->last_mount = le32_to_cpu(s->last_mount);

sb->first_bucket = le16_to_cpu(s->first_bucket);
sb->keys = le16_to_cpu(s->keys);

Expand Down Expand Up @@ -147,53 +139,77 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
if (bch_is_zero(sb->uuid, 16))
goto err;

err = "Unsupported superblock version";
if (sb->version > BCACHE_SB_VERSION)
goto err;
switch (sb->version) {
case BCACHE_SB_VERSION_BDEV:
sb->block_size = le16_to_cpu(s->block_size);
sb->data_offset = BDEV_DATA_START_DEFAULT;
break;
case BCACHE_SB_VERSION_BDEV_WITH_OFFSET:
sb->block_size = le16_to_cpu(s->block_size);
sb->data_offset = le64_to_cpu(s->data_offset);

err = "Bad data offset";
if (sb->data_offset < BDEV_DATA_START_DEFAULT)
goto err;

err = "Bad block/bucket size";
if (!is_power_of_2(sb->block_size) || sb->block_size > PAGE_SECTORS ||
!is_power_of_2(sb->bucket_size) || sb->bucket_size < PAGE_SECTORS)
goto err;
break;
case BCACHE_SB_VERSION_CDEV:
case BCACHE_SB_VERSION_CDEV_WITH_UUID:
sb->nbuckets = le64_to_cpu(s->nbuckets);
sb->block_size = le16_to_cpu(s->block_size);
sb->bucket_size = le16_to_cpu(s->bucket_size);

err = "Too many buckets";
if (sb->nbuckets > LONG_MAX)
goto err;
sb->nr_in_set = le16_to_cpu(s->nr_in_set);
sb->nr_this_dev = le16_to_cpu(s->nr_this_dev);

err = "Not enough buckets";
if (sb->nbuckets < 1 << 7)
goto err;
err = "Too many buckets";
if (sb->nbuckets > LONG_MAX)
goto err;

err = "Invalid superblock: device too small";
if (get_capacity(bdev->bd_disk) < sb->bucket_size * sb->nbuckets)
goto err;
err = "Not enough buckets";
if (sb->nbuckets < 1 << 7)
goto err;

if (sb->version == CACHE_BACKING_DEV)
goto out;
err = "Bad block/bucket size";
if (!is_power_of_2(sb->block_size) ||
sb->block_size > PAGE_SECTORS ||
!is_power_of_2(sb->bucket_size) ||
sb->bucket_size < PAGE_SECTORS)
goto err;

err = "Bad UUID";
if (bch_is_zero(sb->set_uuid, 16))
goto err;
err = "Invalid superblock: device too small";
if (get_capacity(bdev->bd_disk) < sb->bucket_size * sb->nbuckets)
goto err;

err = "Bad cache device number in set";
if (!sb->nr_in_set ||
sb->nr_in_set <= sb->nr_this_dev ||
sb->nr_in_set > MAX_CACHES_PER_SET)
goto err;
err = "Bad UUID";
if (bch_is_zero(sb->set_uuid, 16))
goto err;

err = "Journal buckets not sequential";
for (i = 0; i < sb->keys; i++)
if (sb->d[i] != sb->first_bucket + i)
err = "Bad cache device number in set";
if (!sb->nr_in_set ||
sb->nr_in_set <= sb->nr_this_dev ||
sb->nr_in_set > MAX_CACHES_PER_SET)
goto err;

err = "Too many journal buckets";
if (sb->first_bucket + sb->keys > sb->nbuckets)
goto err;
err = "Journal buckets not sequential";
for (i = 0; i < sb->keys; i++)
if (sb->d[i] != sb->first_bucket + i)
goto err;

err = "Invalid superblock: first bucket comes before end of super";
if (sb->first_bucket * sb->bucket_size < 16)
err = "Too many journal buckets";
if (sb->first_bucket + sb->keys > sb->nbuckets)
goto err;

err = "Invalid superblock: first bucket comes before end of super";
if (sb->first_bucket * sb->bucket_size < 16)
goto err;

break;
default:
err = "Unsupported superblock version";
goto err;
out:
}

sb->last_mount = get_seconds();
err = NULL;

Expand Down Expand Up @@ -286,7 +302,7 @@ void bcache_write_super(struct cache_set *c)
for_each_cache(ca, c, i) {
struct bio *bio = &ca->sb_bio;

ca->sb.version = BCACHE_SB_VERSION;
ca->sb.version = BCACHE_SB_VERSION_CDEV_WITH_UUID;
ca->sb.seq = c->sb.seq;
ca->sb.last_mount = c->sb.last_mount;

Expand Down Expand Up @@ -1049,7 +1065,7 @@ static const char *register_bdev(struct cache_sb *sb, struct page *sb_page,

g = dc->disk.disk;

set_capacity(g, dc->bdev->bd_part->nr_sects - 16);
set_capacity(g, dc->bdev->bd_part->nr_sects - dc->sb.data_offset);

bch_cached_dev_request_init(dc);

Expand Down Expand Up @@ -1802,7 +1818,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
if (err)
goto err_close;

if (sb->version == CACHE_BACKING_DEV) {
if (SB_IS_BDEV(sb)) {
struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);

err = register_bdev(sb, sb_page, bdev, dc);
Expand Down

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