Re: [REGRESSION] smb: client: batch SRV_COPYCHUNK entries to cut round trips - 6.12.y EIO above 12 MiB with SMB3 encryption

[Paulo Alcantara <pc@manguebit.org>]

Paul Aurich <paul@darkrain42.org> writes:

> On 2026-10-15 16:54:29 -0300, Paulo Alcantara wrote:
>>Thanks for the report.
>>
>>Paul Aurich <paul@darkrain42.org> writes:
>>
>>> In stable 6.12.y releases, a copy_file_range request exceeding 12 MiB on an
>>> encrypted SMB3 mount fails with EIO and a WARN_ON_ONCE() splat in
>>> SMB2_ioctl_init:
>>>
>>>      # cp /mnt/otters/13mib.bin /mnt/otters/output.bin
>>>      cp: error copying '/mnt/otters/13mib.bin' to '/mnt/otters/output.bin':
>>>      Input/output error
>>>
>>> Works in 6.12.110.  Fails in 6.12.111 through 6.12.113 (latest).  Via
>>> bisection, introduced by 8d103b285359 ("smb: client: batch SRV_COPYCHUNK
>>> entries to cut round trips").
>>
>>Does it work if you backport the other 3 missing commits?
>
> Yes.  With v6.12.113 + bc925c1216f0 + 9f544d26b15b + 90f7c100d2dd, 'cp' and 
> the Python reproducer work.  (Tested with both a 13 MiB file and a 250 MiB 
> file)

Thanks for testing it!

Greg,

Could you please backport the following to v6.12.y

	bc925c1216f0 ("smb: client: improve compound padding in encryption")
	9f544d26b15b ("smb: client: get rid of bounds check in SMB2_ioctl_init()")
	90f7c100d2dd ("smb: client: fix compound alignment with encryption")

Thanks.