From ffa470327572b8f85dceda48fd0676d9658cb8c5 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 25 Jul 2020 20:00:35 +0800 Subject: bcache: add bucket_size_hi into struct cache_sb_disk for large bucket The large bucket feature is to extend bucket_size from 16bit to 32bit. When create cache device on zoned device (e.g. zoned NVMe SSD), making a single bucket cover one or more zones of the zoned device is the simplest way to support zoned device as cache by bcache. But current maximum bucket size is 16MB and a typical zone size of zoned device is 256MB, this is the major motiviation to extend bucket size to a larger bit width. This patch is the basic and first change to support large bucket size, the major changes it makes are, - Add BCH_FEATURE_INCOMPAT_LARGE_BUCKET for the large bucket feature, INCOMPAT means it introduces incompatible on-disk format change. - Add BCH_FEATURE_INCOMPAT_FUNCS(large_bucket, LARGE_BUCKET) routines. - Adds __le16 bucket_size_hi into struct cache_sb_disk at offset 0x8d0 for the on-disk super block format. - For the in-memory super block struct cache_sb, member bucket_size is extended from __u16 to __32. - Add get_bucket_size() to combine the bucket_size and bucket_size_hi from struct cache_sb_disk into an unsigned int value. Since we already have large bucket size helpers meta_bucket_pages(), meta_bucket_bytes() and alloc_meta_bucket_pages(), they make sure when bucket size > 8MB, the memory allocation for bcache meta data bucket won't fail no matter how large the bucket size extended. So these meta data buckets are handled properly when the bucket size width increase from 16bit to 32bit, we don't need to worry about them. Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/super.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) (limited to 'drivers/md/bcache/super.c') diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index e4f05c4ddcdd..62c9681fe92f 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -60,6 +60,17 @@ struct workqueue_struct *bch_journal_wq; /* Superblock */ +static unsigned int get_bucket_size(struct cache_sb *sb, struct cache_sb_disk *s) +{ + unsigned int bucket_size = le16_to_cpu(s->bucket_size); + + if (sb->version >= BCACHE_SB_VERSION_CDEV_WITH_FEATURES && + bch_has_feature_large_bucket(sb)) + bucket_size |= le16_to_cpu(s->bucket_size_hi) << 16; + + return bucket_size; +} + static const char *read_super_common(struct cache_sb *sb, struct block_device *bdev, struct cache_sb_disk *s) { @@ -68,7 +79,7 @@ static const char *read_super_common(struct cache_sb *sb, struct block_device * sb->first_bucket= le16_to_cpu(s->first_bucket); sb->nbuckets = le64_to_cpu(s->nbuckets); - sb->bucket_size = le16_to_cpu(s->bucket_size); + sb->bucket_size = get_bucket_size(sb, s); sb->nr_in_set = le16_to_cpu(s->nr_in_set); sb->nr_this_dev = le16_to_cpu(s->nr_this_dev); @@ -210,12 +221,16 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev, goto err; break; case BCACHE_SB_VERSION_CDEV_WITH_FEATURES: - err = read_super_common(sb, bdev, s); - if (err) - goto err; + /* + * Feature bits are needed in read_super_common(), + * convert them firstly. + */ sb->feature_compat = le64_to_cpu(s->feature_compat); sb->feature_incompat = le64_to_cpu(s->feature_incompat); sb->feature_ro_compat = le64_to_cpu(s->feature_ro_compat); + err = read_super_common(sb, bdev, s); + if (err) + goto err; break; default: err = "Unsupported superblock version"; -- cgit v1.2.3