> 2023年5月17日 11:51，Lin Feng <linf@xxxxxxxxxx> 写道：
>
> In fact due to this check in cache_alloc:
> free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
This was introduced from commit 78365411b344d (“bcache: Rework allocator reserves”).
- free = roundup_pow_of_two(ca->sb.nbuckets) >> 9;
- free = max_t(size_t, free, (prio_buckets(ca) + 8) * 2);
+ free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
> if (!free) {
> ret = -EPERM;
> err = "ca->sb.nbuckets is too small";
> goto err_free;
> }
> we can only create bcache device with nbuckets greater than 512,
> so this patch is to make the codes logic consistent.
>
> Signed-off-by: Lin Feng <linf@xxxxxxxxxx>
> ---
> drivers/md/bcache/super.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 7e9d19fd21dd..681a7ea442b9 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -110,7 +110,7 @@ static const char *read_super_common(struct cache_sb *sb, struct block_device *
> goto err;
>
> err = "Not enough buckets";
> - if (sb->nbuckets < 1 << 7)
> + if (sb->nbuckets <= 1 << 9)
if (roundup_pow_of_two(ca->sb.nbuckets) < 1<< 10)
Might be more clear?
> goto err;
>
> err = "Bad block size (not power of 2)";
In bcache-tools the minimum nbuckets is (1<<7) too. It is fine to modify it to 1<<10, I will modify bcache-tools too.
Nice catch, thanks!
Coly
