Re: [PATCH 3/3] btrfs-progs: convert: report available space before convertion happens

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

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On 2020/7/29 下午5:05, Su Yue wrote:
> 
> On Wed 29 Jul 2020 at 16:40, Qu Wenruo <wqu@suse.com> wrote:
> 
>> Now if an ENOSPC error happened, the free space report would
>> help user to determine if it's a real ENOSPC or a bug in btrfs.
>>
>> The reported free space is the calculated free space, which
>> doesn't include super block space, nor merged data chunks.
>>
>> The free space is always smaller than the reported available
>> space of the original fs, as we need extra padding space for
>> used space to avoid too fragmented data chunks.
>>
>> The output exact would be:
>>
>> $ ./btrfs-convert  /dev/nvme/btrfs create btrfs filesystem:
>>         blocksize: 4096 nodesize:  16384 features:  extref,
>>         skinny-metadata (default) checksum:  crc32c
>> free space report: free / total = 0 / 10737418240 (0%) <<<
>> ERROR: unable to create initial ctree: No space left on device
>> WARNING: an error occurred during conversion, the original
>> filesystem is not modified
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com> ---
>>  convert/common.h    |  9 +++++++++ convert/main.c      | 26
>>  ++++++++++++++++++++++++-- convert/source-fs.c |  1 + 3 files
>>  changed, 34 insertions(+), 2 deletions(-)
>>
>> diff --git a/convert/common.h b/convert/common.h index
>> 7ec26cd996d3..2c7799433294 100644 --- a/convert/common.h +++
>> b/convert/common.h @@ -35,6 +35,7 @@ struct
>> btrfs_convert_context {
>>      u64 inodes_count; u64 free_inodes_count; u64 total_bytes;
>> +    u64 free_bytes_initial;
>>      char *volume_name; const struct btrfs_convert_operations
>>  *convert_ops;
>> @@ -47,6 +48,14 @@ struct btrfs_convert_context {
>>      /* Free space which is not covered by data_chunks */ struct
>>  cache_tree free_space;
>> +    /* +     * Free space reserved for ENOSPC report, it's just a
>> copy +     * free_space.  +     * But after initial calculation,
>> free_space_initial is no longer +     * updated, so we have a good
>> idea on how many free space we really +     * have for btrfs.  +
>> */ +    struct cache_tree free_space_initial;
>>      void *fs_data; };
>> diff --git a/convert/main.c b/convert/main.c index
>> 451e4f158689..49c95e092cbb 100644 --- a/convert/main.c +++
>> b/convert/main.c @@ -727,6 +727,23 @@ out:
>>      return ret; }
>> +static int copy_free_space_tree(struct btrfs_convert_context
>> *cctx) +{ +    struct cache_tree *src = &cctx->free_space; +
>> struct cache_tree *dst = &cctx->free_space_initial; +    struct
>> cache_extent *cache; +    int ret = 0; + +    for (cache =
>> search_cache_extent(src, 0); cache; +         cache =
>> next_cache_extent(cache)) { +        ret =
>> add_merge_cache_extent(dst, cache->start, cache->size); +        if
>> (ret < 0) +            return ret; +
>> cctx->free_bytes_initial += cache->size; +    } +    return ret; +}
>> +
>>  /*
>>   * Read used space, and since we have the used space, *
>>   calculate data_chunks and free for later mkfs
>> @@ -740,7 +757,10 @@ static int convert_read_used_space(struct
>> btrfs_convert_context *cctx)
>>          return ret;  ret = calculate_available_space(cctx);
>> -    return ret; +    if (ret < 0) +        return ret; + +    return
>> copy_free_space_tree(cctx);
>>  }  /*
>> @@ -1165,7 +1185,9 @@ static int do_convert(const char *devname,
>> u32 convert_flags, u32 nodesize,
>>      printf("\tnodesize:  %u\n", nodesize); printf("\tfeatures:
>>  %s\n", features_buf); printf("\tchecksum:  %s\n",
>>  btrfs_super_csum_name(csum_type));
>> - +    printf("free space report: free / total = %llu / %llu
>> (%lld%%)\n", +        cctx.free_bytes_initial, cctx.total_bytes,
>> +        cctx.free_bytes_initial * 100 / cctx.total_bytes);
>>      memset(&mkfs_cfg, 0, sizeof(mkfs_cfg)); mkfs_cfg.csum_type =
>>  csum_type; mkfs_cfg.label = cctx.volume_name;
>> diff --git a/convert/source-fs.c b/convert/source-fs.c index
>> f7fd3d6055b7..d2f7a825238d 100644 --- a/convert/source-fs.c +++
>> b/convert/source-fs.c @@ -74,6 +74,7 @@ void
>> init_convert_context(struct btrfs_convert_context *cctx)
>>      cache_tree_init(&cctx->used_space);
>>  cache_tree_init(&cctx->data_chunks);
>>  cache_tree_init(&cctx->free_space);
>> +    cache_tree_init(&cctx->free_space_initial);
>>  }  void clean_convert_context(struct btrfs_convert_context
>>  *cctx)
> 
> Did you forget the clean path? :)

Oh, thanks for that!
Just forgot that.

Thanks,
Qu
> 
> ---
> Su
> 


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