On 2017年11月28日 07:21, David Sterba wrote:
> On Wed, Nov 01, 2017 at 09:30:40AM +0800, Qu Wenruo wrote:
>> +u64 btrfs_min_dev_size(u32 nodesize, int mixed, u64 meta_profile,
>> + u64 data_profile)
>> +{
>> + u64 reserved = 0;
>> + u64 meta_size;
>> + u64 data_size;
>> +
>> + if (mixed)
>> + return 2 * (BTRFS_MKFS_SYSTEM_GROUP_SIZE +
>> + btrfs_min_global_blk_rsv_size(nodesize));
>> +
>> + /*
>> + * minimal size calculation is complex due to several factors:
>> + * 1) Temporary chunk resue
>> + * If specified chunk profile is SINGLE, we can resue
>> + * temporary chunks, no need to alloc new chunks.
>> + *
>> + * 2) Different minimal chunk size for different profile
>> + * For initial sys chunk, chunk size is fixed to 4M.
>> + * For single profile, minimal chunk size is 8M for all.
>> + * For other profiles, minimal chunk and stripe size
>> + * differs from 8M to 64M.
>> + *
>> + * To calculate it a little easier, here we assume we don't
>> + * reuse any temporary chunk, and calculate the size all
>> + * by ourselves.
>> + *
>> + * Temporary chunks sizes are always fixed:
>> + * One initial sys chunk, one SINGLE meta, and one SINGLE data.
>> + * The latter two are all 8M, accroding to @calc_size of
>> + * btrfs_alloc_chunk().
>> + */
>> + reserved += BTRFS_MKFS_SYSTEM_GROUP_SIZE + SZ_8M * 2;
>> +
>> + /*
>> + * For real chunks, we need to refer different sizes:
>> + * For SINGLE, it's still fixed to 8M (@calc_size).
>> + * For other profiles, refer to max(@min_stripe_size, @calc_size).
>> + *
>> + * And use the stripe size to calculate its physical used space.
>> + */
>> + if (meta_profile & BTRFS_BLOCK_GROUP_PROFILE_MASK)
>> + meta_size = SZ_8M + SZ_32M;
>> + else
>> + meta_size = SZ_8M + SZ_8M;
>> + /* Only metadata put 2 stripes into one disk */
>
> 'mkfs.btrfs -d dup' also works, so I think this should be handled here
> the same way as metadata, right?Just a few lines under. > >> + if (meta_profile & BTRFS_BLOCK_GROUP_DUP) >> + meta_size *= 2; >> + reserved += meta_size; >> + >> + if (data_profile & BTRFS_BLOCK_GROUP_PROFILE_MASK) >> + data_size = SZ_64M; >> + else >> + data_size = SZ_8M; >> + if (data_profile & BTRFS_BLOCK_GROUP_DUP) >> + data_size *= 2; Here data DUP is also handled. So the problem is about the word "Only". Do I need to re-submit the whole patchset or just a separate patch to update the comment? Thanks, Qu >> + reserved += data_size; >> + return reserved; >> +} > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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