Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-22 Thread Nicholas A. Bellinger
On Mon, 2014-09-22 at 14:00 -0700, Andy Grover wrote: > On 09/22/2014 01:58 PM, Nicholas A. Bellinger wrote: > > So I'd still like to start for an initial merge with the two different > > modes mentioned earlier. The pure-passthrough mode where everything is > > handled by user-space, and an I/O p

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-22 Thread Andy Grover
On 09/22/2014 01:58 PM, Nicholas A. Bellinger wrote: So I'd still like to start for an initial merge with the two different modes mentioned earlier. The pure-passthrough mode where everything is handled by user-space, and an I/O passthrough mode where only SCF_SCSI_DATA_CDB is passed along to us

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-22 Thread Nicholas A. Bellinger
On Fri, 2014-09-19 at 17:35 -0700, Andy Grover wrote: > On 09/19/2014 04:51 PM, Alex Elsayed wrote: > > >> Not sure I follow.. How does the proposed passthrough mode prevent > >> someone from emulating OSDs, media changers, optical disks or anything > >> else in userspace with TCMU..? > >> > >> T

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-22 Thread Nicholas A. Bellinger
On Fri, 2014-09-19 at 16:51 -0700, Alex Elsayed wrote: > Nicholas A. Bellinger wrote: > > > On Fri, 2014-09-19 at 14:43 -0700, Alex Elsayed wrote: > >> Nicholas A. Bellinger wrote: > >> > >> > >> > So the idea of allowing the in-kernel CDB emulation to run after > >> > user-space has returned un

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-19 Thread Andy Grover
On 09/19/2014 04:51 PM, Alex Elsayed wrote: Not sure I follow.. How does the proposed passthrough mode prevent someone from emulating OSDs, media changers, optical disks or anything else in userspace with TCMU..? The main thing that the above comments highlight is why attempting to combine the

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-19 Thread Alex Elsayed
Nicholas A. Bellinger wrote: > On Fri, 2014-09-19 at 14:43 -0700, Alex Elsayed wrote: >> Nicholas A. Bellinger wrote: >> >> >> > So the idea of allowing the in-kernel CDB emulation to run after >> > user-space has returned unsupported opcode is problematic for a couple >> > of different reasons.

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-19 Thread Nicholas A. Bellinger
On Fri, 2014-09-19 at 14:43 -0700, Alex Elsayed wrote: > Nicholas A. Bellinger wrote: > > > > So the idea of allowing the in-kernel CDB emulation to run after > > user-space has returned unsupported opcode is problematic for a couple > > of different reasons. > > > > First, if the correct featur

Re: [PATCH 4/4] target: Add a user-passthrough backstore

2014-09-19 Thread Nicholas A. Bellinger
Hi Andy, A few comments are inline below. On Mon, 2014-09-15 at 16:12 -0700, Andy Grover wrote: > Add a LIO storage engine that presents commands to userspace for execution. > This would allow more complex backstores to be implemented out-of-kernel, > and also make experimentation a-la FUSE (but

[PATCH 4/4] target: Add a user-passthrough backstore

2014-09-15 Thread Andy Grover
Add a LIO storage engine that presents commands to userspace for execution. This would allow more complex backstores to be implemented out-of-kernel, and also make experimentation a-la FUSE (but at the SCSI level -- "SUSE"?) possible. It uses a mmap()able UIO device per LUN to share a command ring