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([2001:b07:6468:f312:b20a:b600:521c:512d]) by smtp.gmail.com with ESMTPSA id k8sm11927105wma.16.2020.09.19.08.18.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 19 Sep 2020 08:18:09 -0700 (PDT) Subject: Re: [PATCH 1/2] file-posix: Correctly read max_segments of SG nodes To: Dmitry Fomichev , Maxim Levitsky , Max Reitz , Kevin Wolf , Fam Zheng , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= References: <20200811225122.17342-1-dmitry.fomichev@wdc.com> <20200811225122.17342-2-dmitry.fomichev@wdc.com> <808e395e-6f99-acdb-03dc-400f6bd32311@redhat.com> <9f2614db9bcf570be9c9bcb0337126bc711ef432.camel@redhat.com> From: Paolo Bonzini Message-ID: <0d5dbf40-133e-4dd8-de03-ec8744cb90c6@redhat.com> Date: Sat, 19 Sep 2020 17:18:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/19 11:03:07 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Damien Le Moal , Alistair Francis , "qemu-devel@nongnu.org" , "qemu-block@nongnu.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 17/09/20 18:44, Dmitry Fomichev wrote: > > Maxim, looks like you are on top of this problem and your approach sounds > sensible too me. Just FYI, it is also possible to avoid using SG_GET_SG_TABLESIZE > ioctl and rely entirely on sysfs, but the code gets a bit more complicated (see below) I would prefer to have the code in block/ but I have no problem if the hardware limits are placed in a new field of bs->bl. Then scsi-block and scsi-generic can consult it instead of bs->bl.max_transfer. Paolo