On 2018年02月27日 18:01, Su Yue wrote:
>
>
> On 02/27/2018 05:12 PM, Qu Wenruo wrote:
>> Original --check-data-csum option will skip the extra copy if the first
>> copy matches csum.
>>
>> Since offline scrub (with recoverability report) is still out-of-tree, at
>> least enhance --check-data-csum option to handle multiple copies.
>>
>> Signed-off-by: Qu Wenruo <w...@suse.com>
>> ---
>> check/main.c | 65
>> ++++++++++++++++++++++++++++++------------------------------
>> 1 file changed, 32 insertions(+), 33 deletions(-)
>>
>> diff --git a/check/main.c b/check/main.c
>> index 97baae583f04..f25fdc765d63 100644
>> --- a/check/main.c
>> +++ b/check/main.c
>> @@ -5381,42 +5381,37 @@ static int check_extent_csums(struct
>> btrfs_root *root, u64 bytenr,
>> if (!data)
>> return -ENOMEM;
>> + num_copies = btrfs_num_copies(root->fs_info, bytenr, num_bytes);
>> while (offset < num_bytes) {
>> - mirror = 0;
>> -again:
>> - read_len = num_bytes - offset;
>> - /* read as much space once a time */
>> - ret = read_extent_data(fs_info, data + offset,
>> - bytenr + offset, &read_len, mirror);
>> - if (ret)
>> - goto out;
>> - data_checked = 0;
>> - /* verify every 4k data's checksum */
>> - while (data_checked < read_len) {
>> - csum = ~(u32)0;
>> - tmp = offset + data_checked;
>> -
>> - csum = btrfs_csum_data((char *)data + tmp,
>> - csum, fs_info->sectorsize);
>> - btrfs_csum_final(csum, (u8 *)&csum);
>> -
>> - csum_offset = leaf_offset +
>> - tmp / fs_info->sectorsize * csum_size;
>> - read_extent_buffer(eb, (char *)&csum_expected,
>> - csum_offset, csum_size);
>> - /* try another mirror */
>> - if (csum != csum_expected) {
>> - fprintf(stderr, "mirror %d bytenr %llu csum %u
>> expected csum %u\n",
>> + for (mirror = 1; mirror <= num_copies; mirror++) {
>
> Got your point.
> But what confuses me is that why mirror starts from 1 here.
> The mirror influences btrfs_map_block() which is not related
> to this patch though.
mirror number has different meanings in fact.
For 0, it means try to read *ANY* valid copy, it can be the copy of a
duplication, or even rebuilt data from RAID5/6.
For 1, it means the fist copy. Either the only copy of
SINGLE/RAID0/RAID5/6, or the first copy of RAID1/10.
For 2, it means the 2nd copy, it can be real copy for RAID1/RAID10, or
rebuilt data from RAID5/6.
And in fact Liu Bo is adding new copy numbers for RAID5/6 to allow us to
specify how to build the missing data for RAID6.
So here starting from mirror 1 is the correct behavior.
Thanks,
Qu
>
> Thanks,
> Su
>> + read_len = num_bytes - offset;
>> + /* read as much space once a time */
>> + ret = read_extent_data(fs_info, data + offset,
>> + bytenr + offset, &read_len, mirror);
>> + if (ret)
>> + goto out;
>> +
>> + data_checked = 0;
>> + /* verify every 4k data's checksum */
>> + while (data_checked < read_len) {
>> + csum = ~(u32)0;
>> + tmp = offset + data_checked;
>> +
>> + csum = btrfs_csum_data((char *)data + tmp,
>> + csum, fs_info->sectorsize);
>> + btrfs_csum_final(csum, (u8 *)&csum);
>> +
>> + csum_offset = leaf_offset +
>> + tmp / fs_info->sectorsize * csum_size;
>> + read_extent_buffer(eb, (char *)&csum_expected,
>> + csum_offset, csum_size);
>> + if (csum != csum_expected)
>> + fprintf(stderr,
>> + "mirror %d bytenr %llu csum %u expected csum %u\n",
>> mirror, bytenr + tmp,
>> csum, csum_expected);
>> - num_copies = btrfs_num_copies(root->fs_info,
>> - bytenr, num_bytes);
>> - if (mirror < num_copies - 1) {
>> - mirror += 1;
>> - goto again;
>> - }
>> + data_checked += fs_info->sectorsize;
>> }
>> - data_checked += fs_info->sectorsize;
>> }
>> offset += read_len;
>> }
>> @@ -5624,7 +5619,11 @@ static int check_csums(struct btrfs_root *root)
>> leaf_offset = btrfs_item_ptr_offset(leaf, path.slots[0]);
>> ret = check_extent_csums(root, key.offset, data_len,
>> leaf_offset, leaf);
>> - if (ret)
>> + /*
>> + * Only break for fatal errors, if mismatch is found,
>> + * continue checking until all extents are checked.
>> + */
>> + if (ret < 0)
>> break;
>> skip_csum_check:
>> if (!num_bytes) {
>>
>
>
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