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Date: Mon, 23 Dec 2013 11:45:02 +0100
From: Julian Elischer <julian@freebsd.org>
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To: Konstantin Belousov <kostikbel@gmail.com>, Manfred Antar <null@pozo.com>
Subject: Re: vfs_bio.c revision 259200 breaks writing to tape drive on current
References: <201312221754.rBMHssMv004688@pozo.com>
 <20131223073102.GA59496@kib.kiev.ua>
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On 12/23/13, 8:31 AM, Konstantin Belousov wrote:
> On Sun, Dec 22, 2013 at 09:54:49AM -0800, Manfred Antar wrote:
>> The change to vfs_bio.c in revision 259200 breaks writing to scsi tape drive on i386 and sparc64 on current.
>> I don't have any other machines to test on.
>> here is example:
>>
>> r259199:
>> (/)4794}mt rew
>> (/)4795}tar cvf /dev/sa0 kernel
>> a kernel
>>
>> r259200:
>> (/)4781}mt rew
>> (/)4782}tar cvf /dev/sa0 kernel
>> a kerneltar: Write error
>>
>> the changes between the two revisions:
>> line 3682 removed:
>>
>> bp->b_resid = bip->bio_resid;   /* XXX: remove */
>>
>> I noticed this when trying to do a dump and getting end of tape error.
>> tried different tape drives , different cables no change.
>> backed out r259200 to 259199 and everything works as before.
>> Manfred
> Show me the kdump of the tar commands on both revisions.
I had to do all sorts of special handling back in the 1.x days to get 
tape drives to work correctly. length and resid ahndlign were 
susceptible to failure in hte various different schemes of how tape 
drive s shoud work (variable lenght records, fixed length and ather 
variations I forget) .