On 11/11/14 7:37 AM, Brian Foster wrote:
> On Mon, Nov 10, 2014 at 04:15:35PM -0600, Eric Sandeen wrote:
>> After ffe9a9a xfsprogs: xfs_copy: fix data corruption of target,
>> xfs_copy started hitting an ASSERT for a 4k sector / 4k blocksize
>> filesystem:
>>
>> # dd if=/dev/zero of=test.img bs=1M count=1024
>> # mkfs.xfs -s size=4096 test.img
>> # xfs_copy test.img xfs.img
>> xfs_copy: xfs_copy.c:720: main: Assertion `((((((xfs_daddr_t)(3 << (mp)->m_sectbb_log)) + 1) * (1<<9)) + first_residue) % source_blocksize) == 0' failed.
>> Aborted
>>
>> I started digging through all the calculations below, and realized
>> that in the end, all it wants is the first filesystem block after
>> the AG header. XFS_AGFL_BLOCK(mp) + 1 suffices for this purpose;
>> rip out the rest which seems overly complex and apparently bug-prone.
>>
>> I tested this by creating a 4g filesystem with combinations of
>> sector & block size between 512 and 4k, copying in /lib/modules,
>> running an xfs_copy of that, and running repair against the copy;
>> it all looks good. It took a long time, but I will create a
>> simpler/shorter xfstest based on this.
>>
>> Reported-by: Zorro Lang <zlang@xxxxxxxxxx>
>> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>> ---
>
> Looks Ok to me:
>
> Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
>
> I just noticed the bug... so the problem was basically the assumption
> that sector size == BBSIZE?
To be honest, I never quite figured out what the root cause bug
was; bad me. The previous commit was supposed to *fix* the assumption
that sector size == BBSIZE. But I got lost in all the gyrations.
I guess maybe I should work that out, but I'm not sure it's worth
it. ;)
-Eric
> Brian
>
>>
>> diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
>> index 7ce5ec9..279527c 100644
>> --- a/copy/xfs_copy.c
>> +++ b/copy/xfs_copy.c
>> @@ -475,7 +475,7 @@ main(int argc, char **argv)
>> int open_flags;
>> xfs_off_t pos, end_pos;
>> size_t length;
>> - int c, first_residue, tmp_residue;
>> + int c;
>> __uint64_t size, sizeb;
>> __uint64_t numblocks = 0;
>> int wblocks = 0;
>> @@ -697,27 +697,13 @@ main(int argc, char **argv)
>> ASSERT(source_blocksize % source_sectorsize == 0);
>> ASSERT(source_sectorsize % BBSIZE == 0);
>>
>> - if (source_blocksize > source_sectorsize) {
>> - /* get number of leftover sectors in last block of ag header */
>> -
>> - tmp_residue = ((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
>> - % source_blocksize;
>> - first_residue = (tmp_residue == 0) ? 0 :
>> - source_blocksize - tmp_residue;
>> - ASSERT(first_residue % source_sectorsize == 0);
>> - } else if (source_blocksize == source_sectorsize) {
>> - first_residue = 0;
>> - } else {
>> + if (source_blocksize < source_sectorsize) {
>> do_log(_("Error: filesystem block size is smaller than the"
>> " disk sectorsize.\nAborting XFS copy now.\n"));
>> exit(1);
>> }
>>
>> - first_agbno = (((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
>> - + first_residue) / source_blocksize;
>> - ASSERT(first_agbno != 0);
>> - ASSERT(((((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
>> - + first_residue) % source_blocksize) == 0);
>> + first_agbno = XFS_AGFL_BLOCK(mp) + 1;
>>
>> /* now open targets */
>>
>>
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>
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