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b16671e8f4
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: ffa4703275 ("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>
76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Feature set bits and string conversion.
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* Inspired by ext4's features compat/incompat/ro_compat related code.
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*
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* Copyright 2020 Coly Li <colyli@suse.de>
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*
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*/
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#include <linux/bcache.h>
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#include "bcache.h"
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#include "features.h"
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struct feature {
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int compat;
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unsigned int mask;
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const char *string;
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};
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static struct feature feature_list[] = {
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{BCH_FEATURE_INCOMPAT, BCH_FEATURE_INCOMPAT_LOG_LARGE_BUCKET_SIZE,
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"large_bucket"},
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{0, 0, 0 },
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};
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#define compose_feature_string(type) \
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({ \
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struct feature *f; \
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bool first = true; \
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\
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for (f = &feature_list[0]; f->compat != 0; f++) { \
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if (f->compat != BCH_FEATURE_ ## type) \
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continue; \
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if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask)) { \
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if (first) { \
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out += snprintf(out, buf + size - out, \
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"["); \
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} else { \
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out += snprintf(out, buf + size - out, \
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" ["); \
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} \
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} else if (!first) { \
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out += snprintf(out, buf + size - out, " "); \
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} \
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\
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out += snprintf(out, buf + size - out, "%s", f->string);\
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\
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if (BCH_HAS_ ## type ## _FEATURE(&c->cache->sb, f->mask)) \
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out += snprintf(out, buf + size - out, "]"); \
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\
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first = false; \
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} \
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if (!first) \
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out += snprintf(out, buf + size - out, "\n"); \
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})
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int bch_print_cache_set_feature_compat(struct cache_set *c, char *buf, int size)
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{
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char *out = buf;
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compose_feature_string(COMPAT);
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return out - buf;
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}
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int bch_print_cache_set_feature_ro_compat(struct cache_set *c, char *buf, int size)
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{
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char *out = buf;
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compose_feature_string(RO_COMPAT);
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return out - buf;
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}
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int bch_print_cache_set_feature_incompat(struct cache_set *c, char *buf, int size)
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{
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char *out = buf;
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compose_feature_string(INCOMPAT);
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return out - buf;
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}
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