Re: [PATCH] btrfs: disk-io: Kill the BUG_ON()s in write_and_map_eb()

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2020/3/2 上午11:35, Su Yue wrote:
> 
> On Mon 02 Mar 2020 at 09:41, Qu Wenruo <wqu@suse.com> wrote:
> 
>> All callers of write_and_map_eb(), except btrfs-corrupt-block,
>> have handled error, but inside write_and_map_eb() itself, the
>> only error handling is BUG_ON().
>>
>> This patch will kill all the BUG_ON()s inside
>> write_and_map_eb(), and enhance the the caller in
>> btrfs-corrupt-block() to handle the error.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com> ---
>>  btrfs-corrupt-block.c       |  9 ++++++++-
>>  cmds/rescue-super-recover.c |  3 ++-
> 
> So may the subject be prefixed with "btrfs-progs"?
> 
>>  disk-io.c                   | 26 +++++++++++++++++++++++--- 3
>>  files changed, 33 insertions(+), 5 deletions(-)
>>
>> diff --git a/btrfs-corrupt-block.c b/btrfs-corrupt-block.c index
>> 95df871a7822..3c236e146176 100644 --- a/btrfs-corrupt-block.c
>> +++ b/btrfs-corrupt-block.c @@ -771,8 +771,15 @@ static int
>> corrupt_metadata_block(struct btrfs_fs_info *fs_info, u64 block,
>>          u64 bogus = generate_u64(orig);
>>  btrfs_set_header_generation(eb, bogus);
>> -        write_and_map_eb(fs_info, eb); +        ret =
>> write_and_map_eb(fs_info, eb);
>>          free_extent_buffer(eb);
>> +        if (ret < 0) { +            errno = -ret; +
>> fprintf(stderr, +                "failed to write extent buffer at
>> %llu: %m", +                eb->start); +            return ret; +
>> }
>>          break; } case BTRFS_METADATA_BLOCK_SHIFT_ITEMS:
>> diff --git a/cmds/rescue-super-recover.c
>> b/cmds/rescue-super-recover.c index 5d6bea836c8b..62f4f7754720
>> 100644 --- a/cmds/rescue-super-recover.c +++
>> b/cmds/rescue-super-recover.c @@ -276,7 +276,8 @@ int
>> btrfs_recover_superblocks(const char *dname,
>>                    struct super_block_record, list);  root =
>>  open_ctree(record->device_name, record->bytenr,
>> -              OPEN_CTREE_RECOVER_SUPER | OPEN_CTREE_WRITES); +
>> OPEN_CTREE_RECOVER_SUPER | OPEN_CTREE_WRITES | +
>> OPEN_CTREE_EXCLUSIVE);
> 
> Any explanation about this change?

My bad, unclean base.

I'll resend the patch.

Thanks,
Qu
> 
> Thanks
> 
>>      if (!root) {
>>          ret = 3;
>>          goto no_recover;
>> diff --git a/disk-io.c b/disk-io.c
>> index e8a2e4afa93a..9ff62fcd54d1 100644
>> --- a/disk-io.c
>> +++ b/disk-io.c
>> @@ -487,20 +487,40 @@ int write_and_map_eb(struct btrfs_fs_info
>> *fs_info, struct extent_buffer *eb)
>>      length = eb->len;
>>      ret = btrfs_map_block(fs_info, WRITE, eb->start, &length,
>>                    &multi, 0, &raid_map);
>> +    if (ret < 0) {
>> +        errno = -ret;
>> +        error("failed to map bytenr %llu length %u: %m",
>> +            eb->start, eb->len);
>> +        goto out;
>> +    }
>>
>>      if (raid_map) {
>>          ret = write_raid56_with_parity(fs_info, eb, multi,
>>                             length, raid_map);
>> -        BUG_ON(ret);
>> +        if (ret < 0) {
>> +            errno = -ret;
>> +            error(
>> +        "failed to write raid56 stripe for bytenr %llu length %llu: %m",
>> +                eb->start, length);
>> +            goto out;
>> +        }
>>      } else while (dev_nr < multi->num_stripes) {
>> -        BUG_ON(ret);
>>          eb->fd = multi->stripes[dev_nr].dev->fd;
>>          eb->dev_bytenr = multi->stripes[dev_nr].physical;
>>          multi->stripes[dev_nr].dev->total_ios++;
>>          dev_nr++;
>>          ret = write_extent_to_disk(eb);
>> -        BUG_ON(ret);
>> +        if (ret < 0) {
>> +            errno = -ret;
>> +            error(
>> +"failed to write bytenr %llu length %u devid %llu dev_bytenr %llu: %m",
>> +                eb->start, eb->len,
>> +                multi->stripes[dev_nr].dev->devid,
>> +                eb->dev_bytenr);
>> +            goto out;
>> +        }
>>      }
>> +out:
>>      kfree(raid_map);
>>      kfree(multi);
>>      return 0;
> 


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