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Date: Mon, 8 Apr 2013 12:11:06 +0200
From: Gabriel <g2p.code@...il.com>
To: Kent Overstreet <koverstreet@...gle.com>,
linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Gabriel <g2p.code+bcache@...il.com>
Subject: [PATCH] bcache: Take data offset from the bdev superblock.
Add a new superblock version, and consolidate related defines.
Signed-off-by: Gabriel de Perthuis <g2p.code+bcache@...il.com>
---
drivers/md/bcache/bcache.h | 23 ++++++++++++++++++-----
drivers/md/bcache/request.c | 2 +-
drivers/md/bcache/super.c | 21 ++++++++++++++++-----
3 files changed, 35 insertions(+), 11 deletions(-)
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index f057235..8a110e6 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -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
@@ -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];
@@ -485,6 +490,7 @@ struct cached_dev {
* where it's at.
*/
sector_t last_read;
+ sector_t data_start_sector;
/* Number of writeback bios in flight */
atomic_t in_flight;
@@ -861,6 +867,13 @@ 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 {
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 83731dc..9f74aff 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -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->data_start_sector;
if (cached_dev_get(dc)) {
s = search_alloc(bio, d);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 5fa3cd2..a409bb5 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -148,7 +148,7 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
goto err;
err = "Unsupported superblock version";
- if (sb->version > BCACHE_SB_VERSION)
+ if (sb->version > BCACHE_SB_MAX_VERSION)
goto err;
err = "Bad block/bucket size";
@@ -168,7 +168,7 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
if (get_capacity(bdev->bd_disk) < sb->bucket_size * sb->nbuckets)
goto err;
- if (sb->version == CACHE_BACKING_DEV)
+ if (SB_IS_BDEV(sb))
goto out;
err = "Bad UUID";
@@ -286,7 +286,7 @@ 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;
@@ -1047,9 +1047,20 @@ static const char *register_bdev(struct cache_sb *sb, struct page *sb_page,
dc->bdev = bdev;
dc->bdev->bd_holder = dc;
+ err = "bad start sector";
+ if (sb->version == BCACHE_SB_VERSION_BDEV) {
+ dc->data_start_sector = BDEV_DATA_START_DEFAULT;
+ } else {
+ if (sb->keys < 1)
+ goto err;
+ dc->data_start_sector = sb->d[0];
+ if (dc->data_start_sector < BDEV_DATA_START_DEFAULT)
+ goto err;
+ }
+
g = dc->disk.disk;
- set_capacity(g, dc->bdev->bd_part->nr_sects - 16);
+ set_capacity(g, dc->bdev->bd_part->nr_sects - dc->data_start_sector);
bch_cached_dev_request_init(dc);
@@ -1802,7 +1813,7 @@ 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);
--
1.8.2.rc3.7.g35aca0e
--
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