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 <20121025153731.GI10679@twin.jikos.cz>
From: Rock Lee <zimilo@code-trick.com>
Date: Thu, 25 Oct 2012 23:58:24 +0800
Message-ID: <CAMRmmpLfbzAcf7M5T0UYHv7-R6PeprwGpgb-YfLfWpvp9PA8Gw@mail.gmail.com>
Subject: Re: [BUG][BTRFS-PROGS] Fix Bug to corrupt the img file
To: dave@jikos.cz, Rock Lee <zimilo@code-trick.com>,
        linux-btrfs@vger.kernel.org
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Got it.

2012/10/25 David Sterba <dave@jikos.cz>:
> On Wed, Oct 24, 2012 at 10:04:47AM +0800, Rock Lee wrote:
>> @@ -572,7 +576,7 @@ int btrfs_prepare_device(int fd, char *file, int
>> zero_end, u64 *block_count_ret,
>>                 discard_blocks(fd, 0, block_count);
>>         }
>>
>> -       ret = zero_dev_start(fd);
>> +       ret = zero_dev_start(fd, block_count);
>>         if (ret) {
>>                 fprintf(stderr, "failed to zero device start %d\n", ret);
>>                 exit(1);
>
> Please add a separate check for a minimal image size instead, right after
>
>  553         block_count = device_size(fd, &st);
>  554         if (block_count == 0) {
>  555                 fprintf(stderr, "unable to find %s size\n", file);
>  556                 exit(1);
>  557         }
>  558         if (max_block_count)
>  559                 block_count = min(block_count, max_block_count);
>
>              if (block_count < 2 MB ) {
>                      fprintf(stderr, "Image too small (less than 2MB)");
>                      exit
>              }
>
> thanks,
> david