On 3/12/2014 4:16 AM, Martin K. Petersen wrote:
"Sagi" == Sagi Grimberg <sagig@xxxxxxxxxxxxxxxxxx> writes:
The real question is whether there is actually an I/O path to
protect? It seems somewhat pointless to generate CRCs and then hand
the resulting buffer to a "target" function call that then does a
pass to verify it without any real data movement taking place in
between. The corruption window in that case is fairly small.
Sagi> I agree, it does seem too pedantic, but ignoring scsi_cmnd prot_op
Sagi> feels somewhat wrong to me.
I'm not talking about ignoring the prot_op. The kernel is not going to
request PI transfers (prot_op > 0) unless both initiator and target
agree on the protection mode.
And if you are both initiator and target you are also in control over
the host's prot_capabilities mask and whether you report PROT_EN=1 in
READ CAPACITY(16) for the target.
The kernel may also request the LLD to WRITE_INSERT/READ_STRIP
protection. if I turn
off write_generate/read_verify integrity sysfs attributes. For "real"
device LLDs we know
what to expect but what do we expect from the vhost_scsi LLD to do in
this case?
Sagi.
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