WSL2-Linux-Kernel/drivers/md/bcache/features.c

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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 <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-25 15:00:35 +03:00
// SPDX-License-Identifier: GPL-2.0
/*
* Feature set bits and string conversion.
* Inspired by ext4's features compat/incompat/ro_compat related code.
*
* Copyright 2020 Coly Li <colyli@suse.de>
*
*/
#include <linux/bcache.h>
#include "bcache.h"
#include "features.h"
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 <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-25 15:00:35 +03:00
struct feature {
int compat;
unsigned int mask;
const char *string;
};
static struct feature feature_list[] = {
bcache: introduce BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE for large bucket When large bucket feature was added, BCH_FEATURE_INCOMPAT_LARGE_BUCKET was introduced into the incompat feature set. It used bucket_size_hi (which was added at the tail of struct cache_sb_disk) to extend current 16bit bucket size to 32bit with existing bucket_size in struct cache_sb_disk. This is not a good idea, there are two obvious problems, - Bucket size is always value power of 2, if store log2(bucket size) in existing bucket_size of struct cache_sb_disk, it is unnecessary to add bucket_size_hi. - Macro csum_set() assumes d[SB_JOURNAL_BUCKETS] is the last member in struct cache_sb_disk, bucket_size_hi was added after d[] which makes csum_set calculate an unexpected super block checksum. To fix the above problems, this patch introduces a new incompat feature bit BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE, when this bit is set, it means bucket_size in struct cache_sb_disk stores the order of power-of-2 bucket size value. When user specifies a bucket size larger than 32768 sectors, BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE will be set to incompat feature set, and bucket_size stores log2(bucket size) more than store the real bucket size value. The obsoleted BCH_FEATURE_INCOMPAT_LARGE_BUCKET won't be used anymore, it is renamed to BCH_FEATURE_INCOMPAT_OBSO_LARGE_BUCKET and still only recognized by kernel driver for legacy compatible purpose. The previous bucket_size_hi is renmaed to obso_bucket_size_hi in struct cache_sb_disk and not used in bcache-tools anymore. For cache device created with BCH_FEATURE_INCOMPAT_LARGE_BUCKET feature, bcache-tools and kernel driver still recognize the feature string and display it as "obso_large_bucket". With this change, the unnecessary extra space extend of bcache on-disk super block can be avoided, and csum_set() may generate expected check sum as well. Fixes: ffa470327572 ("bcache: add bucket_size_hi into struct cache_sb_disk for large bucket") Signed-off-by: Coly Li <colyli@suse.de> Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-04 10:41:21 +03:00
{BCH_FEATURE_INCOMPAT, BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE,
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 <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-25 15:00:35 +03:00
"large_bucket"},
{0, 0, NULL },
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 <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-25 15:00:35 +03:00
};
#define compose_feature_string(type) \
({ \
struct feature *f; \
bool first = true; \
\
for (f = &feature_list[0]; f->compat != 0; f++) { \
if (f->compat != BCH_FEATURE_ ## type) \
continue; \
if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask)) { \
if (first) { \
out += snprintf(out, buf + size - out, \
"["); \
} else { \
out += snprintf(out, buf + size - out, \
" ["); \
} \
} else if (!first) { \
out += snprintf(out, buf + size - out, " "); \
} \
\
out += snprintf(out, buf + size - out, "%s", f->string);\
\
if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask)) \
out += snprintf(out, buf + size - out, "]"); \
\
first = false; \
} \
if (!first) \
out += snprintf(out, buf + size - out, "\n"); \
})
int bch_print_cache_set_feature_compat(struct cache_set *c, char *buf, int size)
{
char *out = buf;
compose_feature_string(COMPAT);
return out - buf;
}
int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size)
{
char *out = buf;
compose_feature_string(RO_COMPAT);
return out - buf;
}
int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size)
{
char *out = buf;
compose_feature_string(INCOMPAT);
return out - buf;
}