[RFC-v3 0/4] tcm_vhost+cmwq fabric driver code for-3.6

[RFC-v3 0/4] tcm_vhost+cmwq fabric driver code for-3.6

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

Hi folks,

The following is the RFC-v3 series of tcm_vhost target fabric driver code
currently in-flight for-3.6 mainline code.

With the merge window opening soon, the tcm_vhost code has started seeing
time in linux-next.  The v2 -> v3 changelog from the last week is currently
looking like:

 *) Unlock on error in tcm_vhost_drop_nexus() (DanC)
 *) Fix strlen() doesn't count the terminator (DanC)
 *) Call kfree() on an error path (DanC)
 *) Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
 *) Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
 *) Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
    as requested by MST (nab)

Thanks to Dan Carpenter for his smatch fixes this past round.

Also as requested by MST, the code has been moved to a seperate tcm/ subdirectory
under drivers/vhost/ so that it can be included under staging's config options
until we can settle on the necessary userspace bits for QEMU and kvm-tool.

The updated series will be going out shortly to target-pending/for-next-merge.

Please have another look and let us know if you have any concerned.

Thanks!

Nicholas Bellinger (2):
  vhost: Add vhost_scsi specific defines
  tcm_vhost: Initial merge for vhost level target fabric driver

Stefan Hajnoczi (2):
  vhost: Separate vhost-net features from vhost features
  vhost: make vhost work queue visible

 drivers/staging/Kconfig       |    2 +
 drivers/vhost/Makefile        |    2 +
 drivers/vhost/net.c           |    4 +-
 drivers/vhost/tcm/Kconfig     |    6 +
 drivers/vhost/tcm/Makefile    |    1 +
 drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
 drivers/vhost/tcm/tcm_vhost.h |   74 ++
 drivers/vhost/test.c          |    4 +-
 drivers/vhost/vhost.c         |    5 +-
 drivers/vhost/vhost.h         |    6 +-
 include/linux/vhost.h         |    9 +
 11 files changed, 1716 insertions(+), 8 deletions(-)
 create mode 100644 drivers/vhost/tcm/Kconfig
 create mode 100644 drivers/vhost/tcm/Makefile
 create mode 100644 drivers/vhost/tcm/tcm_vhost.c
 create mode 100644 drivers/vhost/tcm/tcm_vhost.h

-- 
1.7.2.5

[RFC-v3 1/4] vhost: Separate vhost-net features from vhost features

[Nicholas A. Bellinger]

From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

In order for other vhost devices to use the VHOST_FEATURES bits the
vhost-net specific bits need to be moved to their own VHOST_NET_FEATURES
constant.

(Asias: Update drivers/vhost/test.c to use VHOST_NET_FEATURES)

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Asias He <asias@redhat.com>
Signed-off-by: Nicholas A. Bellinger <nab@risingtidesystems.com>
---
 drivers/vhost/net.c   |    4 ++--
 drivers/vhost/test.c  |    4 ++--
 drivers/vhost/vhost.h |    3 ++-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f82a739..072cbba 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -823,14 +823,14 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		return vhost_net_set_backend(n, backend.index, backend.fd);
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_NET_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;
 	case VHOST_SET_FEATURES:
 		if (copy_from_user(&features, featurep, sizeof features))
 			return -EFAULT;
-		if (features & ~VHOST_FEATURES)
+		if (features & ~VHOST_NET_FEATURES)
 			return -EOPNOTSUPP;
 		return vhost_net_set_features(n, features);
 	case VHOST_RESET_OWNER:
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index 3de00d9..91d6f06 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -261,14 +261,14 @@ static long vhost_test_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		return vhost_test_run(n, test);
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_NET_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;
 	case VHOST_SET_FEATURES:
 		if (copy_from_user(&features, featurep, sizeof features))
 			return -EFAULT;
-		if (features & ~VHOST_FEATURES)
+		if (features & ~VHOST_NET_FEATURES)
 			return -EOPNOTSUPP;
 		return vhost_test_set_features(n, features);
 	case VHOST_RESET_OWNER:
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 8de1fd5..07b9763 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -201,7 +201,8 @@ enum {
 	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
-			 (1ULL << VHOST_F_LOG_ALL) |
+			 (1ULL << VHOST_F_LOG_ALL),
+	VHOST_NET_FEATURES = VHOST_FEATURES |
 			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 };
-- 
1.7.2.5

[RFC-v3 2/4] vhost: make vhost work queue visible

[Nicholas A. Bellinger]

From: Stefan Hajnoczi <stefanha@gmail.com>

The vhost work queue allows processing to be done in vhost worker thread
context, which uses the owner process mm.  Access to the vring and guest
memory is typically only possible from vhost worker context so it is
useful to allow work to be queued directly by users.

Currently vhost_net only uses the poll wrappers which do not expose the
work queue functions.  However, for tcm_vhost (vhost_scsi) it will be
necessary to queue custom work.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/vhost/vhost.c |    5 ++---
 drivers/vhost/vhost.h |    3 +++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 94dbd25..1aab08b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -64,7 +64,7 @@ static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync,
 	return 0;
 }
 
-static void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
+void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn)
 {
 	INIT_LIST_HEAD(&work->node);
 	work->fn = fn;
@@ -137,8 +137,7 @@ void vhost_poll_flush(struct vhost_poll *poll)
 	vhost_work_flush(poll->dev, &poll->work);
 }
 
-static inline void vhost_work_queue(struct vhost_dev *dev,
-				    struct vhost_work *work)
+void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 {
 	unsigned long flags;
 
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 07b9763..1125af3 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -43,6 +43,9 @@ struct vhost_poll {
 	struct vhost_dev	 *dev;
 };
 
+void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
+void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
+
 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 		     unsigned long mask, struct vhost_dev *dev);
 void vhost_poll_start(struct vhost_poll *poll, struct file *file);
-- 
1.7.2.5

[RFC-v3 3/4] vhost: Add vhost_scsi specific defines

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@risingtidesystems.com>

This patch adds the initial vhost_scsi_ioctl() callers for VHOST_SCSI_SET_ENDPOINT
and VHOST_SCSI_CLEAR_ENDPOINT respectively, and also adds struct vhost_vring_target
that is used by tcm_vhost code when locating target ports during qemu setup.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Signed-off-by: Nicholas A. Bellinger <nab@risingtidesystems.com>
---
 include/linux/vhost.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/include/linux/vhost.h b/include/linux/vhost.h
index e847f1e..33b313b 100644
--- a/include/linux/vhost.h
+++ b/include/linux/vhost.h
@@ -24,7 +24,11 @@ struct vhost_vring_state {
 struct vhost_vring_file {
 	unsigned int index;
 	int fd; /* Pass -1 to unbind from file. */
+};
 
+struct vhost_vring_target {
+	unsigned char vhost_wwpn[224];
+	unsigned short vhost_tpgt;
 };
 
 struct vhost_vring_addr {
@@ -121,6 +125,11 @@ struct vhost_memory {
  * device.  This can be used to stop the ring (e.g. for migration). */
 #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
 
+/* VHOST_SCSI specific defines */
+
+#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
+#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
+
 /* Feature bits */
 /* Log all write descriptors. Can be changed while device is active. */
 #define VHOST_F_LOG_ALL 26
-- 
1.7.2.5

Re: [RFC-v3 3/4] vhost: Add vhost_scsi specific defines

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 12:59:31AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@risingtidesystems.com>
> 
> This patch adds the initial vhost_scsi_ioctl() callers for VHOST_SCSI_SET_ENDPOINT
> and VHOST_SCSI_CLEAR_ENDPOINT respectively, and also adds struct vhost_vring_target
> that is used by tcm_vhost code when locating target ports during qemu setup.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>,
> Signed-off-by: Nicholas A. Bellinger <nab@risingtidesystems.com>
> ---
>  include/linux/vhost.h |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/vhost.h b/include/linux/vhost.h
> index e847f1e..33b313b 100644
> --- a/include/linux/vhost.h
> +++ b/include/linux/vhost.h
> @@ -24,7 +24,11 @@ struct vhost_vring_state {
>  struct vhost_vring_file {
>  	unsigned int index;
>  	int fd; /* Pass -1 to unbind from file. */
> +};
>  
> +struct vhost_vring_target {

Can this be renamed vhost_scsi_target?

> +	unsigned char vhost_wwpn[224];

224? I am guessing ISCSI_NAME_LEN from include/scsi/iscsi_proto.h?
Unfortunately we can't include iscsi_proto.h here as it
is not exported to users. But let's add a comment for now.

> +	unsigned short vhost_tpgt;
>  };
>  
>  struct vhost_vring_addr {
> @@ -121,6 +125,11 @@ struct vhost_memory {
>   * device.  This can be used to stop the ring (e.g. for migration). */
>  #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
>  
> +/* VHOST_SCSI specific defines */
> +
> +#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
> +#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
> +
>  /* Feature bits */
>  /* Log all write descriptors. Can be changed while device is active. */

Can these go into appropriate ifdef CONFIG_TCP_VHOST please?

>  #define VHOST_F_LOG_ALL 26
> -- 
> 1.7.2.5

Re: [RFC-v3 3/4] vhost: Add vhost_scsi specific defines

[Nicholas A. Bellinger]

On Wed, 2012-07-18 at 16:05 +0300, Michael S. Tsirkin wrote:
> On Wed, Jul 18, 2012 at 12:59:31AM +0000, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@risingtidesystems.com>
> > 
> > This patch adds the initial vhost_scsi_ioctl() callers for VHOST_SCSI_SET_ENDPOINT
> > and VHOST_SCSI_CLEAR_ENDPOINT respectively, and also adds struct vhost_vring_target
> > that is used by tcm_vhost code when locating target ports during qemu setup.
> > 
> > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> > Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
> > Cc: Michael S. Tsirkin <mst@redhat.com>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>,
> > Signed-off-by: Nicholas A. Bellinger <nab@risingtidesystems.com>
> > ---
> >  include/linux/vhost.h |    9 +++++++++
> >  1 files changed, 9 insertions(+), 0 deletions(-)
> > 
> > diff --git a/include/linux/vhost.h b/include/linux/vhost.h
> > index e847f1e..33b313b 100644
> > --- a/include/linux/vhost.h
> > +++ b/include/linux/vhost.h
> > @@ -24,7 +24,11 @@ struct vhost_vring_state {
> >  struct vhost_vring_file {
> >  	unsigned int index;
> >  	int fd; /* Pass -1 to unbind from file. */
> > +};
> >  
> > +struct vhost_vring_target {
> 
> Can this be renamed vhost_scsi_target?

Done

> 
> > +	unsigned char vhost_wwpn[224];
> 
> 224? I am guessing ISCSI_NAME_LEN from include/scsi/iscsi_proto.h?
> Unfortunately we can't include iscsi_proto.h here as it
> is not exported to users. But let's add a comment for now.
> 

This is actually from target/target_core_base.h:TRANSPORT_IQN_LEN.

Fixing this up now..

> > +	unsigned short vhost_tpgt;
> >  };
> >  
> >  struct vhost_vring_addr {
> > @@ -121,6 +125,11 @@ struct vhost_memory {
> >   * device.  This can be used to stop the ring (e.g. for migration). */
> >  #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
> >  
> > +/* VHOST_SCSI specific defines */
> > +
> > +#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
> > +#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
> > +
> >  /* Feature bits */
> >  /* Log all write descriptors. Can be changed while device is active. */
> 
> Can these go into appropriate ifdef CONFIG_TCP_VHOST please?
> 

Mmmmm, I don't think we can do that with CONFIG_TCM_VHOST=m, or at least
not with the following patch

diff --git a/include/linux/vhost.h b/include/linux/vhost.h
index 33b313b..e4b1ee3 100644
--- a/include/linux/vhost.h
+++ b/include/linux/vhost.h
@@ -125,10 +126,14 @@ struct vhost_memory {
  * device.  This can be used to stop the ring (e.g. for migration). */
 #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
 
+#ifdef CONFIG_TCM_VHOST
+
 /* VHOST_SCSI specific defines */
 
-#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
-#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
+# define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_scsi_target)
+# define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_scsi_target)
+
+#endif

--

drivers/vhost/tcm/tcm_vhost.c: In function ‘vhost_scsi_ioctl’:
drivers/vhost/tcm/tcm_vhost.c:970: error: ‘VHOST_SCSI_SET_ENDPOINT’ undeclared (first use in this function)
drivers/vhost/tcm/tcm_vhost.c:970: error: (Each undeclared identifier is reported only once
drivers/vhost/tcm/tcm_vhost.c:970: error: for each function it appears in.)
drivers/vhost/tcm/tcm_vhost.c:975: error: ‘VHOST_SCSI_CLEAR_ENDPOINT’ undeclared (first use in this function)
make[3]: *** [drivers/vhost/tcm/tcm_vhost.o] Error 1


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Re: [RFC-v3 3/4] vhost: Add vhost_scsi specific defines

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 02:17:05PM -0700, Nicholas A. Bellinger wrote:
> On Wed, 2012-07-18 at 16:05 +0300, Michael S. Tsirkin wrote:
> > On Wed, Jul 18, 2012 at 12:59:31AM +0000, Nicholas A. Bellinger wrote:
> > > From: Nicholas Bellinger <nab@risingtidesystems.com>
> > > 
> > > This patch adds the initial vhost_scsi_ioctl() callers for VHOST_SCSI_SET_ENDPOINT
> > > and VHOST_SCSI_CLEAR_ENDPOINT respectively, and also adds struct vhost_vring_target
> > > that is used by tcm_vhost code when locating target ports during qemu setup.
> > > 
> > > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> > > Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
> > > Cc: Michael S. Tsirkin <mst@redhat.com>
> > > Cc: Paolo Bonzini <pbonzini@redhat.com>,
> > > Signed-off-by: Nicholas A. Bellinger <nab@risingtidesystems.com>
> > > ---
> > >  include/linux/vhost.h |    9 +++++++++
> > >  1 files changed, 9 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/include/linux/vhost.h b/include/linux/vhost.h
> > > index e847f1e..33b313b 100644
> > > --- a/include/linux/vhost.h
> > > +++ b/include/linux/vhost.h
> > > @@ -24,7 +24,11 @@ struct vhost_vring_state {
> > >  struct vhost_vring_file {
> > >  	unsigned int index;
> > >  	int fd; /* Pass -1 to unbind from file. */
> > > +};
> > >  
> > > +struct vhost_vring_target {
> > 
> > Can this be renamed vhost_scsi_target?
> 
> Done
> 
> > 
> > > +	unsigned char vhost_wwpn[224];
> > 
> > 224? I am guessing ISCSI_NAME_LEN from include/scsi/iscsi_proto.h?
> > Unfortunately we can't include iscsi_proto.h here as it
> > is not exported to users. But let's add a comment for now.
> > 
> 
> This is actually from target/target_core_base.h:TRANSPORT_IQN_LEN.
> 
> Fixing this up now..
> 
> > > +	unsigned short vhost_tpgt;
> > >  };
> > >  
> > >  struct vhost_vring_addr {
> > > @@ -121,6 +125,11 @@ struct vhost_memory {
> > >   * device.  This can be used to stop the ring (e.g. for migration). */
> > >  #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
> > >  
> > > +/* VHOST_SCSI specific defines */
> > > +
> > > +#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
> > > +#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
> > > +
> > >  /* Feature bits */
> > >  /* Log all write descriptors. Can be changed while device is active. */
> > 
> > Can these go into appropriate ifdef CONFIG_TCP_VHOST please?
> > 
> 
> Mmmmm, I don't think we can do that with CONFIG_TCM_VHOST=m, or at least
> not with the following patch
> 
> diff --git a/include/linux/vhost.h b/include/linux/vhost.h
> index 33b313b..e4b1ee3 100644
> --- a/include/linux/vhost.h
> +++ b/include/linux/vhost.h
> @@ -125,10 +126,14 @@ struct vhost_memory {
>   * device.  This can be used to stop the ring (e.g. for migration). */
>  #define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
>  
> +#ifdef CONFIG_TCM_VHOST
> +
>  /* VHOST_SCSI specific defines */
>  
> -#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_vring_target)
> -#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_vring_target)
> +# define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_scsi_target)
> +# define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_scsi_target)
> +
> +#endif
> 
> --
> 
> drivers/vhost/tcm/tcm_vhost.c: In function ‘vhost_scsi_ioctl’:
> drivers/vhost/tcm/tcm_vhost.c:970: error: ‘VHOST_SCSI_SET_ENDPOINT’ undeclared (first use in this function)
> drivers/vhost/tcm/tcm_vhost.c:970: error: (Each undeclared identifier is reported only once
> drivers/vhost/tcm/tcm_vhost.c:970: error: for each function it appears in.)
> drivers/vhost/tcm/tcm_vhost.c:975: error: ‘VHOST_SCSI_CLEAR_ENDPOINT’ undeclared (first use in this function)
> make[3]: *** [drivers/vhost/tcm/tcm_vhost.o] Error 1


Maybe ifdefs only work for booleans? If yes you can probably add a boolean and select it?
What I want to prevent is exposing tcm stuff in the header if it is
configured off. I'll play with it tomorrow.
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[RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Nicholas A. Bellinger]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch adds the initial code for tcm_vhost, a Vhost level TCM
fabric driver for virtio SCSI initiators into KVM guest.

This code is currently up and running on v3.5-rc2 host+guest along
with the virtio-scsi vdev->scan() patch to allow a proper
scsi_scan_host() to occur once the tcm_vhost nexus has been established
by the paravirtualized virtio-scsi client here:

virtio-scsi: Add vdrv->scan for post VIRTIO_CONFIG_S_DRIVER_OK LUN scanning
http://marc.info/?l=linux-scsi&m=134160609212542&w=2

Using tcm_vhost requires Zhi's -> Stefan's qemu vhost-scsi tree here:

https://github.com/wuzhy/qemu/tree/vhost-scsi

along with the recent QEMU patch to hw/virtio-scsi.c to set max_target=0
during vhost-scsi operation.

Changelog v2 -> v3:

  Unlock on error in tcm_vhost_drop_nexus() (DanC)
  Fix strlen() doesn't count the terminator (DanC)
  Call kfree() on an error path (DanC)
  Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
  Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
  Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
  as requested by MST (nab)

Changelog v1 -> v2:

  Fix tv_cmd completion -> release SGL memory leak (nab)
  Fix sparse warnings for static variable usage ((Fengguang Wu)
  Fix sparse warnings for min() typing + printk format specs (Fengguang Wu)
  Convert to cmwq submission for I/O dispatch (nab + hch)

Changelog v0 -> v1:

  Merge into single source + header file, and move to drivers/vhost/

Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 drivers/staging/Kconfig       |    2 +
 drivers/vhost/Makefile        |    2 +
 drivers/vhost/tcm/Kconfig     |    6 +
 drivers/vhost/tcm/Makefile    |    1 +
 drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
 drivers/vhost/tcm/tcm_vhost.h |   74 ++
 6 files changed, 1696 insertions(+), 0 deletions(-)
 create mode 100644 drivers/vhost/tcm/Kconfig
 create mode 100644 drivers/vhost/tcm/Makefile
 create mode 100644 drivers/vhost/tcm/tcm_vhost.c
 create mode 100644 drivers/vhost/tcm/tcm_vhost.h

diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 05e33c7..8d1a627 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -132,4 +132,6 @@ source "drivers/staging/ipack/Kconfig"
 
 source "drivers/staging/gdm72xx/Kconfig"
 
+source "drivers/vhost/tcm/Kconfig"
+
 endif # STAGING
diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
index 72dd020..3408bea 100644
--- a/drivers/vhost/Makefile
+++ b/drivers/vhost/Makefile
@@ -1,2 +1,4 @@
 obj-$(CONFIG_VHOST_NET) += vhost_net.o
 vhost_net-y := vhost.o net.o
+
+obj-$(CONFIG_TCM_VHOST) += tcm/
diff --git a/drivers/vhost/tcm/Kconfig b/drivers/vhost/tcm/Kconfig
new file mode 100644
index 0000000..a9c6f76
--- /dev/null
+++ b/drivers/vhost/tcm/Kconfig
@@ -0,0 +1,6 @@
+config TCM_VHOST
+	tristate "TCM_VHOST fabric module (EXPERIMENTAL)"
+	depends on TARGET_CORE && EVENTFD && EXPERIMENTAL && m
+	default n
+	---help---
+	Say M here to enable the TCM_VHOST fabric module for use with virtio-scsi guests
diff --git a/drivers/vhost/tcm/Makefile b/drivers/vhost/tcm/Makefile
new file mode 100644
index 0000000..54b0ea6
--- /dev/null
+++ b/drivers/vhost/tcm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_TCM_VHOST) += tcm_vhost.o
diff --git a/drivers/vhost/tcm/tcm_vhost.c b/drivers/vhost/tcm/tcm_vhost.c
new file mode 100644
index 0000000..0ee4046
--- /dev/null
+++ b/drivers/vhost/tcm/tcm_vhost.c
@@ -0,0 +1,1611 @@
+/*******************************************************************************
+ * Vhost kernel TCM fabric driver for virtio SCSI initiators
+ *
+ * (C) Copyright 2010-2012 RisingTide Systems LLC.
+ * (C) Copyright 2010-2012 IBM Corp.
+ *
+ * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
+ *
+ * Authors: Nicholas A. Bellinger <nab@risingtidesystems.com>
+ *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ ****************************************************************************/
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <generated/utsrelease.h>
+#include <linux/utsname.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/configfs.h>
+#include <linux/ctype.h>
+#include <linux/compat.h>
+#include <linux/eventfd.h>
+#include <linux/vhost.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <asm/unaligned.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_tcq.h>
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+#include <target/target_core_fabric_configfs.h>
+#include <target/target_core_configfs.h>
+#include <target/configfs_macros.h>
+#include <linux/vhost.h>
+#include <linux/virtio_net.h> /* TODO vhost.h currently depends on this */
+#include <linux/virtio_scsi.h>
+
+#include "../vhost.c"
+#include "../vhost.h"
+#include "tcm_vhost.h"
+
+struct vhost_scsi {
+	atomic_t vhost_ref_cnt;
+	struct tcm_vhost_tpg *vs_tpg;
+	struct vhost_dev dev;
+	struct vhost_virtqueue vqs[3];
+
+	struct vhost_work vs_completion_work; /* cmd completion work item */
+	struct list_head vs_completion_list;  /* cmd completion queue */
+	spinlock_t vs_completion_lock;        /* protects s_completion_list */
+};
+
+/* Local pointer to allocated TCM configfs fabric module */
+static struct target_fabric_configfs *tcm_vhost_fabric_configfs;
+
+static struct workqueue_struct *tcm_vhost_workqueue;
+
+/* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */
+static DEFINE_MUTEX(tcm_vhost_mutex);
+static LIST_HEAD(tcm_vhost_list);
+
+static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static int tcm_vhost_check_false(struct se_portal_group *se_tpg)
+{
+	return 0;
+}
+
+static char *tcm_vhost_get_fabric_name(void)
+{
+	return "vhost";
+}
+
+static u8 tcm_vhost_get_fabric_proto_ident(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_fabric_proto_ident(se_tpg);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_fabric_proto_ident(se_tpg);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_fabric_proto_ident(se_tpg);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_fabric_proto_ident(se_tpg);
+}
+
+static char *tcm_vhost_get_fabric_wwn(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	return &tport->tport_name[0];
+}
+
+static u16 tcm_vhost_get_tag(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	return tpg->tport_tpgt;
+}
+
+static u32 tcm_vhost_get_default_depth(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static u32 tcm_vhost_get_pr_transport_id(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl,
+	struct t10_pr_registration *pr_reg,
+	int *format_code,
+	unsigned char *buf)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+					format_code, buf);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+			format_code, buf);
+}
+
+static u32 tcm_vhost_get_pr_transport_id_len(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl,
+	struct t10_pr_registration *pr_reg,
+	int *format_code)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	case SCSI_PROTOCOL_FCP:
+		return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+					format_code);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+			format_code);
+}
+
+static char *tcm_vhost_parse_pr_out_transport_id(
+	struct se_portal_group *se_tpg,
+	const char *buf,
+	u32 *out_tid_len,
+	char **port_nexus_ptr)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport = tpg->tport;
+
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	case SCSI_PROTOCOL_FCP:
+		return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	case SCSI_PROTOCOL_ISCSI:
+		return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+					port_nexus_ptr);
+	default:
+		pr_err("Unknown tport_proto_id: 0x%02x, using"
+			" SAS emulation\n", tport->tport_proto_id);
+		break;
+	}
+
+	return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+			port_nexus_ptr);
+}
+
+static struct se_node_acl *tcm_vhost_alloc_fabric_acl(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_nacl *nacl;
+
+	nacl = kzalloc(sizeof(struct tcm_vhost_nacl), GFP_KERNEL);
+	if (!nacl) {
+		pr_err("Unable to alocate struct tcm_vhost_nacl\n");
+		return NULL;
+	}
+
+	return &nacl->se_node_acl;
+}
+
+static void tcm_vhost_release_fabric_acl(
+	struct se_portal_group *se_tpg,
+	struct se_node_acl *se_nacl)
+{
+	struct tcm_vhost_nacl *nacl = container_of(se_nacl,
+			struct tcm_vhost_nacl, se_node_acl);
+	kfree(nacl);
+}
+
+static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
+{
+	return;
+}
+
+static int tcm_vhost_shutdown_session(struct se_session *se_sess)
+{
+	return 0;
+}
+
+static void tcm_vhost_close_session(struct se_session *se_sess)
+{
+	return;
+}
+
+static u32 tcm_vhost_sess_get_index(struct se_session *se_sess)
+{
+	return 0;
+}
+
+static int tcm_vhost_write_pending(struct se_cmd *se_cmd)
+{
+	/* Go ahead and process the write immediately */
+	target_execute_cmd(se_cmd);
+	return 0;
+}
+
+static int tcm_vhost_write_pending_status(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static void tcm_vhost_set_default_node_attrs(struct se_node_acl *nacl)
+{
+	return;
+}
+
+static u32 tcm_vhost_get_task_tag(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static int tcm_vhost_get_cmd_state(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *);
+
+static int tcm_vhost_queue_data_in(struct se_cmd *se_cmd)
+{
+	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
+				struct tcm_vhost_cmd, tvc_se_cmd);
+	vhost_scsi_complete_cmd(tv_cmd);
+	return 0;
+}
+
+static int tcm_vhost_queue_status(struct se_cmd *se_cmd)
+{
+	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
+				struct tcm_vhost_cmd, tvc_se_cmd);
+	vhost_scsi_complete_cmd(tv_cmd);
+	return 0;
+}
+
+static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
+{
+	return 0;
+}
+
+static u16 tcm_vhost_set_fabric_sense_len(struct se_cmd *se_cmd, u32 sense_length)
+{
+	return 0;
+}
+
+static u16 tcm_vhost_get_fabric_sense_len(void)
+{
+	return 0;
+}
+
+static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
+{
+	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+
+	/* TODO locking against target/backend threads? */
+	transport_generic_free_cmd(se_cmd, 1);
+
+	if (tv_cmd->tvc_sgl_count) {
+		u32 i;
+		for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
+			put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+
+		kfree(tv_cmd->tvc_sgl);
+	}
+
+	kfree(tv_cmd);
+}
+
+/* Dequeue a command from the completion list */
+static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion(struct vhost_scsi *vs)
+{
+	struct tcm_vhost_cmd *tv_cmd = NULL;
+
+	spin_lock_bh(&vs->vs_completion_lock);
+	if (list_empty(&vs->vs_completion_list)) {
+		spin_unlock_bh(&vs->vs_completion_lock);
+		return NULL;
+	}
+
+	list_for_each_entry(tv_cmd, &vs->vs_completion_list,
+			    tvc_completion_list) {
+		list_del(&tv_cmd->tvc_completion_list);
+		break;
+	}
+	spin_unlock_bh(&vs->vs_completion_lock);
+	return tv_cmd;
+}
+
+/* Fill in status and signal that we are done processing this command
+ *
+ * This is scheduled in the vhost work queue so we are called with the owner
+ * process mm and can access the vring.
+ */
+static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
+{
+	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
+	                                     vs_completion_work);
+	struct tcm_vhost_cmd *tv_cmd;
+
+	while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)) != NULL) {
+		struct virtio_scsi_cmd_resp v_rsp;
+		struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+		int ret;
+
+		pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
+			tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);
+
+		memset(&v_rsp, 0, sizeof(v_rsp));
+		v_rsp.resid = se_cmd->residual_count;
+		/* TODO is status_qualifier field needed? */
+		v_rsp.status = se_cmd->scsi_status;
+		v_rsp.sense_len = se_cmd->scsi_sense_length;
+		memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,
+		       v_rsp.sense_len);
+		ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));
+		if (likely(ret == 0))
+			vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);
+		else
+			pr_err("Faulted on virtio_scsi_cmd_resp\n");
+
+		vhost_scsi_free_cmd(tv_cmd);
+	}
+
+	vhost_signal(&vs->dev, &vs->vqs[2]);
+}
+
+static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
+{
+	struct vhost_scsi *vs = tv_cmd->tvc_vhost;
+
+	pr_debug("%s tv_cmd %p\n", __func__, tv_cmd);
+
+	spin_lock_bh(&vs->vs_completion_lock);
+	list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list);
+	spin_unlock_bh(&vs->vs_completion_lock);
+
+	vhost_work_queue(&vs->dev, &vs->vs_completion_work);
+}
+
+static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
+	struct tcm_vhost_tpg *tv_tpg,
+	struct virtio_scsi_cmd_req *v_req,
+	u32 exp_data_len,
+	int data_direction)
+{
+	struct tcm_vhost_cmd *tv_cmd;
+	struct tcm_vhost_nexus *tv_nexus;
+	struct se_portal_group *se_tpg = &tv_tpg->se_tpg;
+	struct se_session *se_sess;
+	struct se_cmd *se_cmd;
+	int sam_task_attr;
+
+	tv_nexus = tv_tpg->tpg_nexus;
+	if (!tv_nexus) {
+		pr_err("Unable to locate active struct tcm_vhost_nexus\n");
+		return ERR_PTR(-EIO);
+	}
+	se_sess = tv_nexus->tvn_se_sess;
+
+	tv_cmd = kzalloc(sizeof(struct tcm_vhost_cmd), GFP_ATOMIC);
+	if (!tv_cmd) {
+		pr_err("Unable to allocate struct tcm_vhost_cmd\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
+	tv_cmd->tvc_tag = v_req->tag;
+
+	se_cmd = &tv_cmd->tvc_se_cmd;
+	/*
+	 * Locate the SAM Task Attr from virtio_scsi_cmd_req
+	 */
+	sam_task_attr = v_req->task_attr;
+	/*
+	 * Initialize struct se_cmd descriptor from target_core_mod infrastructure
+	 */
+	transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, exp_data_len,
+				data_direction, sam_task_attr,
+				&tv_cmd->tvc_sense_buf[0]);
+
+#if 0	/* FIXME: vhost_scsi_allocate_cmd() BIDI operation */
+	if (bidi)
+		se_cmd->se_cmd_flags |= SCF_BIDI;
+#endif
+	return tv_cmd;
+}
+
+/*
+ * Map a user memory range into a scatterlist
+ *
+ * Returns the number of scatterlist entries used or -errno on error.
+ */
+static int vhost_scsi_map_to_sgl(struct scatterlist *sgl,
+		                 unsigned int sgl_count,
+		                 void __user *ptr, size_t len, int write)
+{
+	struct scatterlist *sg = sgl;
+	unsigned int npages = 0;
+	int ret;
+
+	while (len > 0) {
+		struct page *page;
+		unsigned int offset = (uintptr_t)ptr & ~PAGE_MASK;
+		unsigned int nbytes = min_t(unsigned int,
+				PAGE_SIZE - offset, len);
+
+		if (npages == sgl_count) {
+			ret = -ENOBUFS;
+			goto err;
+		}
+
+		ret = get_user_pages_fast((unsigned long)ptr, 1, write, &page);
+		BUG_ON(ret == 0); /* we should either get our page or fail */
+		if (ret < 0)
+			goto err;
+
+		sg_set_page(sg, page, nbytes, offset);
+		ptr += nbytes;
+		len -= nbytes;
+		sg++;
+		npages++;
+	}
+	return npages;
+
+err:
+	/* Put pages that we hold */
+	for (sg = sgl; sg != &sgl[npages]; sg++)
+		put_page(sg_page(sg));
+	return ret;
+}
+
+static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd,
+                                     struct iovec *iov, unsigned int niov,
+				     int write)
+{
+	int ret;
+	unsigned int i;
+	u32 sgl_count;
+	struct scatterlist *sg;
+
+	/*
+	 * Find out how long sglist needs to be
+	 */
+	sgl_count = 0;
+	for (i = 0; i < niov; i++) {
+		sgl_count += (((uintptr_t)iov[i].iov_base + iov[i].iov_len +
+		             PAGE_SIZE - 1) >> PAGE_SHIFT) -
+		             ((uintptr_t)iov[i].iov_base >> PAGE_SHIFT);
+	}
+	/* TODO overflow checking */
+
+	sg = kmalloc(sizeof(tv_cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
+	if (!sg)
+		return -ENOMEM;
+	pr_debug("%s sg %p sgl_count %u is_err %ld\n", __func__,
+	       sg, sgl_count, IS_ERR(sg));
+	sg_init_table(sg, sgl_count);
+
+	tv_cmd->tvc_sgl = sg;
+	tv_cmd->tvc_sgl_count = sgl_count;
+
+	pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
+	for (i = 0; i < niov; i++) {
+		ret = vhost_scsi_map_to_sgl(sg, sgl_count, iov[i].iov_base,
+		                            iov[i].iov_len, write);
+		if (ret < 0) {
+			for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
+				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+			kfree(tv_cmd->tvc_sgl);
+			tv_cmd->tvc_sgl = NULL;
+			tv_cmd->tvc_sgl_count = 0;
+			return ret;
+		}
+
+		sg += ret;
+		sgl_count -= ret;
+	}
+	return 0;
+}
+
+static void tcm_vhost_submission_work(struct work_struct *work)
+{
+	struct tcm_vhost_cmd *tv_cmd =
+		container_of(work, struct tcm_vhost_cmd, work);
+	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
+	struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
+	int rc, sg_no_bidi = 0;
+	/*
+	 * Locate the struct se_lun pointer based on v_req->lun, and
+	 * attach it to struct se_cmd
+	 */
+	rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, tv_cmd->tvc_lun);
+	if (rc < 0) {
+		pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun);
+		transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd,
+			tv_cmd->tvc_se_cmd.scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+
+	rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb);
+	if (rc == -ENOMEM) {
+		transport_send_check_condition_and_sense(se_cmd,
+				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	} else if (rc < 0) {
+		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
+			tcm_vhost_queue_status(se_cmd);
+		else
+			transport_send_check_condition_and_sense(se_cmd,
+					se_cmd->scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+
+	if (tv_cmd->tvc_sgl_count) {
+		sg_ptr = tv_cmd->tvc_sgl;
+		/*
+		 * For BIDI commands, pass in the extra READ buffer
+		 * to transport_generic_map_mem_to_cmd() below..
+		 */
+/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */
+#if 0
+		if (se_cmd->se_cmd_flags & SCF_BIDI) {
+			sg_bidi_ptr = NULL;
+			sg_no_bidi = 0;
+		}
+#endif
+	} else {
+		sg_ptr = NULL;
+	}
+
+	rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr,
+				tv_cmd->tvc_sgl_count, sg_bidi_ptr,
+				sg_no_bidi);
+	if (rc < 0) {
+		transport_send_check_condition_and_sense(se_cmd,
+				se_cmd->scsi_sense_reason, 0);
+		transport_generic_free_cmd(se_cmd, 0);
+		return;
+	}
+	transport_handle_cdb_direct(se_cmd);
+}
+
+static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
+{
+	struct vhost_virtqueue *vq = &vs->vqs[2];
+	struct virtio_scsi_cmd_req v_req;
+	struct tcm_vhost_tpg *tv_tpg;
+	struct tcm_vhost_cmd *tv_cmd;
+	u32 exp_data_len, data_first, data_num, data_direction;
+	unsigned out, in, i;
+	int head, ret;
+
+	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
+	tv_tpg = vs->vs_tpg;
+	if (unlikely(!tv_tpg)) {
+		pr_err("%s endpoint not set\n", __func__);
+		return;
+	}
+
+	mutex_lock(&vq->mutex);
+	vhost_disable_notify(&vs->dev, vq);
+
+	for (;;) {
+		head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
+					ARRAY_SIZE(vq->iov), &out, &in,
+					NULL, NULL);
+		pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n", head, out, in);
+		/* On error, stop handling until the next kick. */
+		if (unlikely(head < 0))
+			break;
+		/* Nothing new?  Wait for eventfd to tell us they refilled. */
+		if (head == vq->num) {
+			if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
+				vhost_disable_notify(&vs->dev, vq);
+				continue;
+			}
+			break;
+		}
+
+/* FIXME: BIDI operation */
+		if (out == 1 && in == 1) {
+			data_direction = DMA_NONE;
+			data_first = 0;
+			data_num = 0;
+		} else if (out == 1 && in > 1) {
+			data_direction = DMA_FROM_DEVICE;
+			data_first = out + 1;
+			data_num = in - 1;
+		} else if (out > 1 && in == 1) {
+			data_direction = DMA_TO_DEVICE;
+			data_first = 1;
+			data_num = out - 1;
+		} else {
+			pr_err("Invalid buffer layout out: %u in: %u\n", out, in);
+			break;
+		}
+
+		/*
+		 * Check for a sane resp buffer so we can report errors to
+		 * the guest.
+		 */
+		if (unlikely(vq->iov[out].iov_len !=
+					sizeof(struct virtio_scsi_cmd_resp))) {
+			pr_err("Expecting virtio_scsi_cmd_resp, got %zu bytes\n",
+					vq->iov[out].iov_len);
+			break;
+		}
+
+		if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
+			pr_err("Expecting virtio_scsi_cmd_req, got %zu bytes\n",
+					vq->iov[0].iov_len);
+			break;
+		}
+		pr_debug("Calling __copy_from_user: vq->iov[0].iov_base: %p, len: %zu\n",
+				vq->iov[0].iov_base, sizeof(v_req));
+		ret = __copy_from_user(&v_req, vq->iov[0].iov_base, sizeof(v_req));
+		if (unlikely(ret)) {
+			pr_err("Faulted on virtio_scsi_cmd_req\n");
+			break;
+		}
+
+		exp_data_len = 0;
+		for (i = 0; i < data_num; i++) {
+			exp_data_len += vq->iov[data_first + i].iov_len;
+		}
+
+		tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
+					exp_data_len, data_direction);
+		if (IS_ERR(tv_cmd)) {
+			pr_err("vhost_scsi_allocate_cmd failed %ld\n", PTR_ERR(tv_cmd));
+			break;
+		}
+		pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction: %d\n",
+				tv_cmd, exp_data_len, data_direction);
+
+		tv_cmd->tvc_vhost = vs;
+
+		if (unlikely(vq->iov[out].iov_len !=
+		             sizeof(struct virtio_scsi_cmd_resp))) {
+			pr_err("Expecting virtio_scsi_cmd_resp, "
+			       " got %zu bytes, out: %d, in: %d\n", vq->iov[out].iov_len, out, in);
+			break;
+		}
+
+		tv_cmd->tvc_resp = vq->iov[out].iov_base;
+
+		/*
+		 * Copy in the recieved CDB descriptor into tv_cmd->tvc_cdb
+		 * that will be used by tcm_vhost_new_cmd_map() and down into
+		 * target_setup_cmd_from_cdb()
+		 */
+		memcpy(tv_cmd->tvc_cdb, v_req.cdb, TCM_VHOST_MAX_CDB_SIZE);
+		/*
+		 * Check that the recieved CDB size does not exceeded our
+		 * hardcoded max for tcm_vhost
+		 */
+		/* TODO what if cdb was too small for varlen cdb header? */
+		if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) > TCM_VHOST_MAX_CDB_SIZE)) {
+			pr_err("Received SCSI CDB with command_size: %d that exceeds"
+				" SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
+				scsi_command_size(tv_cmd->tvc_cdb), TCM_VHOST_MAX_CDB_SIZE);
+			break; /* TODO */
+		}
+		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
+
+		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
+			tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);
+
+		if (data_direction != DMA_NONE) {
+			ret = vhost_scsi_map_iov_to_sgl(tv_cmd, &vq->iov[data_first],
+					data_num, data_direction == DMA_TO_DEVICE);
+			if (unlikely(ret)) {
+				pr_err("Failed to map iov to sgl\n");
+				break; /* TODO */
+			}
+		}
+
+		/*
+		 * Save the descriptor from vhost_get_vq_desc() to be used to
+		 * complete the virtio-scsi request in TCM callback context via
+		 * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
+		 */
+		tv_cmd->tvc_vq_desc = head;
+		/*
+		 * Dispatch tv_cmd descriptor for cmwq execution in process
+		 * context provided by tcm_vhost_workqueue.  This also ensures
+		 * tv_cmd is executed on the same kworker CPU as this vhost
+		 * thread to gain positive L2 cache locality effects..
+		 */
+		INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
+		queue_work(tcm_vhost_workqueue, &tv_cmd->work);
+	}
+
+	mutex_unlock(&vq->mutex);
+}
+
+static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
+{
+     pr_err("%s: The handling func for control queue.\n", __func__);
+}
+
+static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
+{
+     pr_err("%s: The handling func for event queue.\n", __func__);
+}
+
+static void vhost_scsi_handle_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						poll.work);
+	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
+
+	vhost_scsi_handle_vq(vs);
+}
+
+/*
+ * Called from vhost_scsi_ioctl() context to walk the list of available tcm_vhost_tpg
+ * with an active struct tcm_vhost_nexus
+ */
+static int vhost_scsi_set_endpoint(
+	struct vhost_scsi *vs,
+	struct vhost_vring_target *t)
+{
+	struct tcm_vhost_tport *tv_tport;
+	struct tcm_vhost_tpg *tv_tpg;
+        int index;
+
+	mutex_lock(&vs->dev.mutex);
+	/* Verify that ring has been setup correctly. */
+	for (index = 0; index < vs->dev.nvqs; ++index) {
+		/* Verify that ring has been setup correctly. */
+		if (!vhost_vq_access_ok(&vs->vqs[index])) {
+		        mutex_unlock(&vs->dev.mutex);
+			return -EFAULT;
+		}
+	}
+
+	if (vs->vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return -EEXIST;
+	}
+	mutex_unlock(&vs->dev.mutex);
+
+	mutex_lock(&tcm_vhost_mutex);
+	list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
+		mutex_lock(&tv_tpg->tv_tpg_mutex);
+		if (!tv_tpg->tpg_nexus) {
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			continue;
+		}
+		if (atomic_read(&tv_tpg->tv_tpg_vhost_count)) {
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			continue;
+		}
+		tv_tport = tv_tpg->tport;
+
+		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
+		    (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
+			atomic_inc(&tv_tpg->tv_tpg_vhost_count);
+			smp_mb__after_atomic_inc();
+			mutex_unlock(&tv_tpg->tv_tpg_mutex);
+			mutex_unlock(&tcm_vhost_mutex);
+
+			mutex_lock(&vs->dev.mutex);
+			vs->vs_tpg = tv_tpg;
+			atomic_inc(&vs->vhost_ref_cnt);
+			smp_mb__after_atomic_inc();
+			mutex_unlock(&vs->dev.mutex);
+			return 0;
+		}
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+	}
+	mutex_unlock(&tcm_vhost_mutex);
+	return -EINVAL;
+}
+
+static int vhost_scsi_clear_endpoint(
+	struct vhost_scsi *vs,
+	struct vhost_vring_target *t)
+{
+	struct tcm_vhost_tport *tv_tport;
+	struct tcm_vhost_tpg *tv_tpg;
+        int index;
+
+	mutex_lock(&vs->dev.mutex);
+	/* Verify that ring has been setup correctly. */
+	for (index = 0; index < vs->dev.nvqs; ++index) {
+		if (!vhost_vq_access_ok(&vs->vqs[index])) {
+		        mutex_unlock(&vs->dev.mutex);
+			return -EFAULT;
+		}
+	}
+
+	if (!vs->vs_tpg) {
+		mutex_unlock(&vs->dev.mutex);
+		return -ENODEV;
+	}
+	tv_tpg = vs->vs_tpg;
+	tv_tport = tv_tpg->tport;
+
+	if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
+	    (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
+		mutex_unlock(&vs->dev.mutex);
+		pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
+			" does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
+			tv_tport->tport_name, tv_tpg->tport_tpgt,
+			t->vhost_wwpn, t->vhost_tpgt);
+		return -EINVAL;
+	}
+        atomic_dec(&tv_tpg->tv_tpg_vhost_count);
+	vs->vs_tpg = NULL;
+	mutex_unlock(&vs->dev.mutex);
+
+	return 0;
+}
+
+static int vhost_scsi_open(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi *s;
+	int r;
+
+	s = kzalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
+	INIT_LIST_HEAD(&s->vs_completion_list);
+	spin_lock_init(&s->vs_completion_lock);
+
+	s->vqs[0].handle_kick = vhost_scsi_ctl_handle_kick;
+	s->vqs[1].handle_kick = vhost_scsi_evt_handle_kick;
+	s->vqs[2].handle_kick = vhost_scsi_handle_kick;
+	r = vhost_dev_init(&s->dev, s->vqs, 3);
+	if (r < 0) {
+		kfree(s);
+		return r;
+	}
+
+	f->private_data = s;
+	return 0;
+}
+
+static int vhost_scsi_release(struct inode *inode, struct file *f)
+{
+	struct vhost_scsi *s = f->private_data;
+
+        if (s->vs_tpg && s->vs_tpg->tport) {
+            struct vhost_vring_target backend;
+            memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name, sizeof(backend.vhost_wwpn));
+            backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
+            vhost_scsi_clear_endpoint(s, &backend);
+        }
+
+	vhost_dev_cleanup(&s->dev, false);
+	kfree(s);
+	return 0;
+}
+
+static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
+{
+	if (features & ~VHOST_FEATURES)
+		return -EOPNOTSUPP;
+
+	mutex_lock(&vs->dev.mutex);
+	if ((features & (1 << VHOST_F_LOG_ALL)) &&
+	    !vhost_log_access_ok(&vs->dev)) {
+		mutex_unlock(&vs->dev.mutex);
+		return -EFAULT;
+	}
+	vs->dev.acked_features = features;
+	/* TODO possibly smp_wmb() and flush vqs */
+	mutex_unlock(&vs->dev.mutex);
+	return 0;
+}
+
+static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
+				unsigned long arg)
+{
+	struct vhost_scsi *vs = f->private_data;
+	struct vhost_vring_target backend;
+	void __user *argp = (void __user *)arg;
+	u64 __user *featurep = argp;
+	u64 features;
+	int r;
+
+	switch (ioctl) {
+	case VHOST_SCSI_SET_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+
+		return vhost_scsi_set_endpoint(vs, &backend);
+	case VHOST_SCSI_CLEAR_ENDPOINT:
+		if (copy_from_user(&backend, argp, sizeof backend))
+			return -EFAULT;
+
+		return vhost_scsi_clear_endpoint(vs, &backend);
+	case VHOST_GET_FEATURES:
+		features = VHOST_FEATURES;
+		if (copy_to_user(featurep, &features, sizeof features))
+			return -EFAULT;
+		return 0;
+	case VHOST_SET_FEATURES:
+		if (copy_from_user(&features, featurep, sizeof features))
+			return -EFAULT;
+		return vhost_scsi_set_features(vs, features);
+	default:
+		mutex_lock(&vs->dev.mutex);
+		r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
+		mutex_unlock(&vs->dev.mutex);
+		return r;
+	}
+}
+
+static const struct file_operations vhost_scsi_fops = {
+	.owner          = THIS_MODULE,
+	.release        = vhost_scsi_release,
+	.unlocked_ioctl = vhost_scsi_ioctl,
+	/* TODO compat ioctl? */
+	.open           = vhost_scsi_open,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice vhost_scsi_misc = {
+	MISC_DYNAMIC_MINOR,
+	"vhost-scsi",
+	&vhost_scsi_fops,
+};
+
+static int __init vhost_scsi_register(void)
+{
+	return misc_register(&vhost_scsi_misc);
+}
+
+static int vhost_scsi_deregister(void)
+{
+	return misc_deregister(&vhost_scsi_misc);
+}
+
+static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
+{
+	switch (tport->tport_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return "SAS";
+	case SCSI_PROTOCOL_FCP:
+		return "FCP";
+	case SCSI_PROTOCOL_ISCSI:
+		return "iSCSI";
+	default:
+		break;
+	}
+
+	return "Unknown";
+}
+
+static int tcm_vhost_port_link(
+	struct se_portal_group *se_tpg,
+	struct se_lun *lun)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	atomic_inc(&tv_tpg->tv_tpg_port_count);
+	smp_mb__after_atomic_inc();
+
+	return 0;
+}
+
+static void tcm_vhost_port_unlink(
+	struct se_portal_group *se_tpg,
+	struct se_lun *se_lun)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	atomic_dec(&tv_tpg->tv_tpg_port_count);
+	smp_mb__after_atomic_dec();
+}
+
+static struct se_node_acl *tcm_vhost_make_nodeacl(
+	struct se_portal_group *se_tpg,
+	struct config_group *group,
+	const char *name)
+{
+	struct se_node_acl *se_nacl, *se_nacl_new;
+	struct tcm_vhost_nacl *nacl;
+	u64 wwpn = 0;
+	u32 nexus_depth;
+
+	/* tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
+		return ERR_PTR(-EINVAL); */
+	se_nacl_new = tcm_vhost_alloc_fabric_acl(se_tpg);
+	if (!se_nacl_new)
+		return ERR_PTR(-ENOMEM);
+//#warning FIXME: Hardcoded nexus depth in tcm_vhost_make_nodeacl()
+	nexus_depth = 1;
+	/*
+	 * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
+	 * when converting a NodeACL from demo mode -> explict
+	 */
+	se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
+				name, nexus_depth);
+	if (IS_ERR(se_nacl)) {
+		tcm_vhost_release_fabric_acl(se_tpg, se_nacl_new);
+		return se_nacl;
+	}
+	/*
+	 * Locate our struct tcm_vhost_nacl and set the FC Nport WWPN
+	 */
+	nacl = container_of(se_nacl, struct tcm_vhost_nacl, se_node_acl);
+	nacl->iport_wwpn = wwpn;
+	/* tcm_vhost_format_wwn(&nacl->iport_name[0], TCM_VHOST_NAMELEN, wwpn); */
+
+	return se_nacl;
+}
+
+static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
+{
+	struct tcm_vhost_nacl *nacl = container_of(se_acl,
+				struct tcm_vhost_nacl, se_node_acl);
+	core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
+	kfree(nacl);
+}
+
+static int tcm_vhost_make_nexus(
+	struct tcm_vhost_tpg *tv_tpg,
+	const char *name)
+{
+	struct se_portal_group *se_tpg;
+	struct tcm_vhost_nexus *tv_nexus;
+
+	mutex_lock(&tv_tpg->tv_tpg_mutex);
+	if (tv_tpg->tpg_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_debug("tv_tpg->tpg_nexus already exists\n");
+		return -EEXIST;
+	}
+	se_tpg = &tv_tpg->se_tpg;
+
+	tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
+	if (!tv_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_err("Unable to allocate struct tcm_vhost_nexus\n");
+		return -ENOMEM;
+	}
+	/*
+	 *  Initialize the struct se_session pointer
+	 */
+	tv_nexus->tvn_se_sess = transport_init_session();
+	if (IS_ERR(tv_nexus->tvn_se_sess)) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		kfree(tv_nexus);
+		return -ENOMEM;
+	}
+	/*
+	 * Since we are running in 'demo mode' this call with generate a
+	 * struct se_node_acl for the tcm_vhost struct se_portal_group with
+	 * the SCSI Initiator port name of the passed configfs group 'name'.
+	 */
+	tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
+				se_tpg, (unsigned char *)name);
+	if (!tv_nexus->tvn_se_sess->se_node_acl) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		pr_debug("core_tpg_check_initiator_node_acl() failed"
+				" for %s\n", name);
+		transport_free_session(tv_nexus->tvn_se_sess);
+		kfree(tv_nexus);
+		return -ENOMEM;
+	}
+	/*
+	 * Now register the TCM vHost virtual I_T Nexus as active with the
+	 * call to __transport_register_session()
+	 */
+	__transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
+			tv_nexus->tvn_se_sess, tv_nexus);
+	tv_tpg->tpg_nexus = tv_nexus;
+
+	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+	return 0;
+}
+
+static int tcm_vhost_drop_nexus(
+	struct tcm_vhost_tpg *tpg)
+{
+	struct se_session *se_sess;
+	struct tcm_vhost_nexus *tv_nexus;
+
+	mutex_lock(&tpg->tv_tpg_mutex);
+	tv_nexus = tpg->tpg_nexus;
+	if (!tv_nexus) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+
+	se_sess = tv_nexus->tvn_se_sess;
+	if (!se_sess) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+
+	if (atomic_read(&tpg->tv_tpg_port_count)) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vHost I_T Nexus with"
+			" active TPG port count: %d\n",
+			atomic_read(&tpg->tv_tpg_port_count));
+		return -EPERM;
+	}
+
+	if (atomic_read(&tpg->tv_tpg_vhost_count)) {
+		mutex_unlock(&tpg->tv_tpg_mutex);
+		pr_err("Unable to remove TCM_vHost I_T Nexus with"
+			" active TPG vhost count: %d\n",
+			atomic_read(&tpg->tv_tpg_vhost_count));
+		return -EPERM;
+	}
+
+	pr_debug("TCM_vHost_ConfigFS: Removing I_T Nexus to emulated"
+		" %s Initiator Port: %s\n", tcm_vhost_dump_proto_id(tpg->tport),
+		tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+	/*
+	 * Release the SCSI I_T Nexus to the emulated vHost Target Port
+	 */
+	transport_deregister_session(tv_nexus->tvn_se_sess);
+	tpg->tpg_nexus = NULL;
+	mutex_unlock(&tpg->tv_tpg_mutex);
+
+	kfree(tv_nexus);
+	return 0;
+}
+
+static ssize_t tcm_vhost_tpg_show_nexus(
+	struct se_portal_group *se_tpg,
+	char *page)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_nexus *tv_nexus;
+	ssize_t ret;
+
+	mutex_lock(&tv_tpg->tv_tpg_mutex);
+	tv_nexus = tv_tpg->tpg_nexus;
+	if (!tv_nexus) {
+		mutex_unlock(&tv_tpg->tv_tpg_mutex);
+		return -ENODEV;
+	}
+	ret = snprintf(page, PAGE_SIZE, "%s\n",
+			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+	mutex_unlock(&tv_tpg->tv_tpg_mutex);
+
+	return ret;
+}
+
+static ssize_t tcm_vhost_tpg_store_nexus(
+	struct se_portal_group *se_tpg,
+	const char *page,
+	size_t count)
+{
+	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+	struct tcm_vhost_tport *tport_wwn = tv_tpg->tport;
+	unsigned char i_port[TCM_VHOST_NAMELEN], *ptr, *port_ptr;
+	int ret;
+	/*
+	 * Shutdown the active I_T nexus if 'NULL' is passed..
+	 */
+	if (!strncmp(page, "NULL", 4)) {
+		ret = tcm_vhost_drop_nexus(tv_tpg);
+		return (!ret) ? count : ret;
+	}
+	/*
+	 * Otherwise make sure the passed virtual Initiator port WWN matches
+	 * the fabric protocol_id set in tcm_vhost_make_tport(), and call
+	 * tcm_vhost_make_nexus().
+	 */
+	if (strlen(page) >= TCM_VHOST_NAMELEN) {
+		pr_err("Emulated NAA Sas Address: %s, exceeds"
+				" max: %d\n", page, TCM_VHOST_NAMELEN);
+		return -EINVAL;
+	}
+	snprintf(&i_port[0], TCM_VHOST_NAMELEN, "%s", page);
+
+	ptr = strstr(i_port, "naa.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
+			pr_err("Passed SAS Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				tcm_vhost_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "fc.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
+			pr_err("Passed FCP Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				tcm_vhost_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[3]; /* Skip over "fc." */
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "iqn.");
+	if (ptr) {
+		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
+			pr_err("Passed iSCSI Initiator Port %s does not"
+				" match target port protoid: %s\n", i_port,
+				tcm_vhost_dump_proto_id(tport_wwn));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	pr_err("Unable to locate prefix for emulated Initiator Port:"
+			" %s\n", i_port);
+	return -EINVAL;
+	/*
+	 * Clear any trailing newline for the NAA WWN
+	 */
+check_newline:
+	if (i_port[strlen(i_port)-1] == '\n')
+		i_port[strlen(i_port)-1] = '\0';
+
+	ret = tcm_vhost_make_nexus(tv_tpg, port_ptr);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+TF_TPG_BASE_ATTR(tcm_vhost, nexus, S_IRUGO | S_IWUSR);
+
+static struct configfs_attribute *tcm_vhost_tpg_attrs[] = {
+	&tcm_vhost_tpg_nexus.attr,
+	NULL,
+};
+
+static struct se_portal_group *tcm_vhost_make_tpg(
+	struct se_wwn *wwn,
+	struct config_group *group,
+	const char *name)
+{
+	struct tcm_vhost_tport*tport = container_of(wwn,
+			struct tcm_vhost_tport, tport_wwn);
+
+	struct tcm_vhost_tpg *tpg;
+	unsigned long tpgt;
+	int ret;
+
+	if (strstr(name, "tpgt_") != name)
+		return ERR_PTR(-EINVAL);
+	if (strict_strtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
+		return ERR_PTR(-EINVAL);
+
+	tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);
+	if (!tpg) {
+		pr_err("Unable to allocate struct tcm_vhost_tpg");
+		return ERR_PTR(-ENOMEM);
+	}
+	mutex_init(&tpg->tv_tpg_mutex);
+	INIT_LIST_HEAD(&tpg->tv_tpg_list);
+	tpg->tport = tport;
+	tpg->tport_tpgt = tpgt;
+
+	ret = core_tpg_register(&tcm_vhost_fabric_configfs->tf_ops, wwn,
+				&tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
+	if (ret < 0) {
+		kfree(tpg);
+		return NULL;
+	}
+	mutex_lock(&tcm_vhost_mutex);
+	list_add_tail(&tpg->tv_tpg_list, &tcm_vhost_list);
+	mutex_unlock(&tcm_vhost_mutex);
+
+	return &tpg->se_tpg;
+}
+
+static void tcm_vhost_drop_tpg(struct se_portal_group *se_tpg)
+{
+	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
+				struct tcm_vhost_tpg, se_tpg);
+
+	mutex_lock(&tcm_vhost_mutex);
+	list_del(&tpg->tv_tpg_list);
+	mutex_unlock(&tcm_vhost_mutex);
+	/*
+	 * Release the virtual I_T Nexus for this vHost TPG
+	 */
+	tcm_vhost_drop_nexus(tpg);
+	/*
+	 * Deregister the se_tpg from TCM..
+	 */
+	core_tpg_deregister(se_tpg);
+	kfree(tpg);
+}
+
+static struct se_wwn *tcm_vhost_make_tport(
+	struct target_fabric_configfs *tf,
+	struct config_group *group,
+	const char *name)
+{
+	struct tcm_vhost_tport *tport;
+	char *ptr;
+	u64 wwpn = 0;
+	int off = 0;
+
+	/* if (tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
+		return ERR_PTR(-EINVAL); */
+
+	tport = kzalloc(sizeof(struct tcm_vhost_tport), GFP_KERNEL);
+	if (!tport) {
+		pr_err("Unable to allocate struct tcm_vhost_tport");
+		return ERR_PTR(-ENOMEM);
+	}
+	tport->tport_wwpn = wwpn;
+	/* tcm_vhost_format_wwn(&tport->tport_name[0], TCM_VHOST__NAMELEN, wwpn); */
+	/*
+	 * Determine the emulated Protocol Identifier and Target Port Name
+	 * based on the incoming configfs directory name.
+	 */
+	ptr = strstr(name, "naa.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_SAS;
+		goto check_len;
+	}
+	ptr = strstr(name, "fc.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_FCP;
+		off = 3; /* Skip over "fc." */
+		goto check_len;
+	}
+	ptr = strstr(name, "iqn.");
+	if (ptr) {
+		tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
+		goto check_len;
+	}
+
+	pr_err("Unable to locate prefix for emulated Target Port:"
+			" %s\n", name);
+	kfree(tport);
+	return ERR_PTR(-EINVAL);
+
+check_len:
+	if (strlen(name) >= TCM_VHOST_NAMELEN) {
+		pr_err("Emulated %s Address: %s, exceeds"
+			" max: %d\n", name, tcm_vhost_dump_proto_id(tport),
+			TCM_VHOST_NAMELEN);
+		kfree(tport);
+		return ERR_PTR(-EINVAL);
+	}
+	snprintf(&tport->tport_name[0], TCM_VHOST_NAMELEN, "%s", &name[off]);
+
+	pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
+		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport), name);
+
+	return &tport->tport_wwn;
+}
+
+static void tcm_vhost_drop_tport(struct se_wwn *wwn)
+{
+	struct tcm_vhost_tport *tport = container_of(wwn,
+				struct tcm_vhost_tport, tport_wwn);
+
+	pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
+		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport),
+		tport->tport_name);;
+
+	kfree(tport);
+}
+
+static ssize_t tcm_vhost_wwn_show_attr_version(
+	struct target_fabric_configfs *tf,
+	char *page)
+{
+	return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
+		"on "UTS_RELEASE"\n", TCM_VHOST_VERSION, utsname()->sysname,
+		utsname()->machine);
+}
+
+TF_WWN_ATTR_RO(tcm_vhost, version);
+
+static struct configfs_attribute *tcm_vhost_wwn_attrs[] = {
+	&tcm_vhost_wwn_version.attr,
+	NULL,
+};
+
+static struct target_core_fabric_ops tcm_vhost_ops = {
+	.get_fabric_name		= tcm_vhost_get_fabric_name,
+	.get_fabric_proto_ident		= tcm_vhost_get_fabric_proto_ident,
+	.tpg_get_wwn			= tcm_vhost_get_fabric_wwn,
+	.tpg_get_tag			= tcm_vhost_get_tag,
+	.tpg_get_default_depth		= tcm_vhost_get_default_depth,
+	.tpg_get_pr_transport_id	= tcm_vhost_get_pr_transport_id,
+	.tpg_get_pr_transport_id_len	= tcm_vhost_get_pr_transport_id_len,
+	.tpg_parse_pr_out_transport_id	= tcm_vhost_parse_pr_out_transport_id,
+	.tpg_check_demo_mode		= tcm_vhost_check_true,
+	.tpg_check_demo_mode_cache	= tcm_vhost_check_true,
+	.tpg_check_demo_mode_write_protect = tcm_vhost_check_false,
+	.tpg_check_prod_mode_write_protect = tcm_vhost_check_false,
+	.tpg_alloc_fabric_acl		= tcm_vhost_alloc_fabric_acl,
+	.tpg_release_fabric_acl		= tcm_vhost_release_fabric_acl,
+	.tpg_get_inst_index		= tcm_vhost_tpg_get_inst_index,
+	.release_cmd			= tcm_vhost_release_cmd,
+	.shutdown_session		= tcm_vhost_shutdown_session,
+	.close_session			= tcm_vhost_close_session,
+	.sess_get_index			= tcm_vhost_sess_get_index,
+	.sess_get_initiator_sid		= NULL,
+	.write_pending			= tcm_vhost_write_pending,
+	.write_pending_status		= tcm_vhost_write_pending_status,
+	.set_default_node_attributes	= tcm_vhost_set_default_node_attrs,
+	.get_task_tag			= tcm_vhost_get_task_tag,
+	.get_cmd_state			= tcm_vhost_get_cmd_state,
+	.queue_data_in			= tcm_vhost_queue_data_in,
+	.queue_status			= tcm_vhost_queue_status,
+	.queue_tm_rsp			= tcm_vhost_queue_tm_rsp,
+	.get_fabric_sense_len		= tcm_vhost_get_fabric_sense_len,
+	.set_fabric_sense_len		= tcm_vhost_set_fabric_sense_len,
+	/*
+	 * Setup function pointers for generic logic in target_core_fabric_configfs.c
+	 */
+	.fabric_make_wwn		= tcm_vhost_make_tport,
+	.fabric_drop_wwn		= tcm_vhost_drop_tport,
+	.fabric_make_tpg		= tcm_vhost_make_tpg,
+	.fabric_drop_tpg		= tcm_vhost_drop_tpg,
+	.fabric_post_link		= tcm_vhost_port_link,
+	.fabric_pre_unlink		= tcm_vhost_port_unlink,
+	.fabric_make_np			= NULL,
+	.fabric_drop_np			= NULL,
+	.fabric_make_nodeacl		= tcm_vhost_make_nodeacl,
+	.fabric_drop_nodeacl		= tcm_vhost_drop_nodeacl,
+};
+
+static int tcm_vhost_register_configfs(void)
+{
+	struct target_fabric_configfs *fabric;
+	int ret;
+
+	pr_debug("TCM_VHOST fabric module %s on %s/%s"
+		" on "UTS_RELEASE"\n",TCM_VHOST_VERSION, utsname()->sysname,
+		utsname()->machine);
+	/*
+	 * Register the top level struct config_item_type with TCM core
+	 */
+	fabric = target_fabric_configfs_init(THIS_MODULE, "vhost");
+	if (IS_ERR(fabric)) {
+		pr_err("target_fabric_configfs_init() failed\n");
+		return PTR_ERR(fabric);
+	}
+	/*
+	 * Setup fabric->tf_ops from our local tcm_vhost_ops
+	 */
+	fabric->tf_ops = tcm_vhost_ops;
+	/*
+	 * Setup default attribute lists for various fabric->tf_cit_tmpl
+	 */
+	TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
+	TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
+	TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
+	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
+	/*
+	 * Register the fabric for use within TCM
+	 */
+	ret = target_fabric_configfs_register(fabric);
+	if (ret < 0) {
+		pr_err("target_fabric_configfs_register() failed"
+				" for TCM_VHOST\n");
+		return ret;
+	}
+	/*
+	 * Setup our local pointer to *fabric
+	 */
+	tcm_vhost_fabric_configfs = fabric;
+	pr_debug("TCM_VHOST[0] - Set fabric -> tcm_vhost_fabric_configfs\n");
+	return 0;
+};
+
+static void tcm_vhost_deregister_configfs(void)
+{
+	if (!tcm_vhost_fabric_configfs)
+		return;
+
+	target_fabric_configfs_deregister(tcm_vhost_fabric_configfs);
+	tcm_vhost_fabric_configfs = NULL;
+	pr_debug("TCM_VHOST[0] - Cleared tcm_vhost_fabric_configfs\n");
+};
+
+static int __init tcm_vhost_init(void)
+{
+	int ret = -ENOMEM;
+
+	tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0);
+	if (!tcm_vhost_workqueue)
+		goto out;
+
+	ret = vhost_scsi_register();
+	if (ret < 0)
+		goto out_destroy_workqueue;
+
+	ret = tcm_vhost_register_configfs();
+	if (ret < 0)
+		goto out_vhost_scsi_deregister;
+
+	return 0;
+
+out_vhost_scsi_deregister:
+	vhost_scsi_deregister();
+out_destroy_workqueue:
+	destroy_workqueue(tcm_vhost_workqueue);
+out:
+	return ret;
+};
+
+static void tcm_vhost_exit(void)
+{
+	tcm_vhost_deregister_configfs();
+	vhost_scsi_deregister();
+	destroy_workqueue(tcm_vhost_workqueue);
+};
+
+MODULE_DESCRIPTION("TCM_VHOST series fabric driver");
+MODULE_LICENSE("GPL");
+module_init(tcm_vhost_init);
+module_exit(tcm_vhost_exit);
diff --git a/drivers/vhost/tcm/tcm_vhost.h b/drivers/vhost/tcm/tcm_vhost.h
new file mode 100644
index 0000000..9d6cace
--- /dev/null
+++ b/drivers/vhost/tcm/tcm_vhost.h
@@ -0,0 +1,74 @@
+#define TCM_VHOST_VERSION  "v0.1"
+#define TCM_VHOST_NAMELEN 256
+#define TCM_VHOST_MAX_CDB_SIZE 32
+
+struct tcm_vhost_cmd {
+	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
+	int tvc_vq_desc;
+	/* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
+	u64 tvc_tag;
+	/* The number of scatterlists associated with this cmd */
+	u32 tvc_sgl_count;
+	/* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
+	u32 tvc_lun;
+	/* Pointer to the SGL formatted memory from virtio-scsi */
+	struct scatterlist *tvc_sgl;
+	/* Pointer to response */
+	struct virtio_scsi_cmd_resp __user *tvc_resp;
+	/* Pointer to vhost_scsi for our device */
+	struct vhost_scsi *tvc_vhost;
+	/* The TCM I/O descriptor that is accessed via container_of() */
+	struct se_cmd tvc_se_cmd;
+	/* work item used for cmwq dispatch to tcm_vhost_submission_work() */
+	struct work_struct work;
+	/* Copy of the incoming SCSI command descriptor block (CDB) */
+	unsigned char tvc_cdb[TCM_VHOST_MAX_CDB_SIZE];
+	/* Sense buffer that will be mapped into outgoing status */
+	unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
+	/* Completed commands list, serviced from vhost worker thread */
+	struct list_head tvc_completion_list;
+};
+
+struct tcm_vhost_nexus {
+	/* Pointer to TCM session for I_T Nexus */
+	struct se_session *tvn_se_sess;
+};
+
+struct tcm_vhost_nacl {
+	/* Binary World Wide unique Port Name for Vhost Initiator port */
+	u64 iport_wwpn;
+	/* ASCII formatted WWPN for Sas Initiator port */
+	char iport_name[TCM_VHOST_NAMELEN];
+	/* Returned by tcm_vhost_make_nodeacl() */
+	struct se_node_acl se_node_acl;
+};
+
+struct tcm_vhost_tpg {
+	/* Vhost port target portal group tag for TCM */
+	u16 tport_tpgt;
+	/* Used to track number of TPG Port/Lun Links wrt to explict I_T Nexus shutdown */
+	atomic_t tv_tpg_port_count;
+	/* Used for vhost_scsi device reference to tpg_nexus */
+	atomic_t tv_tpg_vhost_count;
+	/* list for tcm_vhost_list */
+	struct list_head tv_tpg_list;
+	/* Used to protect access for tpg_nexus */
+	struct mutex tv_tpg_mutex;
+	/* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
+	struct tcm_vhost_nexus *tpg_nexus;
+	/* Pointer back to tcm_vhost_tport */
+	struct tcm_vhost_tport *tport;
+	/* Returned by tcm_vhost_make_tpg() */
+	struct se_portal_group se_tpg;
+};
+
+struct tcm_vhost_tport {
+	/* SCSI protocol the tport is providing */
+	u8 tport_proto_id;
+	/* Binary World Wide unique Port Name for Vhost Target port */
+	u64 tport_wwpn;
+	/* ASCII formatted WWPN for Vhost Target port */
+	char tport_name[TCM_VHOST_NAMELEN];
+	/* Returned by tcm_vhost_make_tport() */
+	struct se_wwn tport_wwn;
+};
-- 
1.7.2.5

Re: [RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 12:59:32AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> This patch adds the initial code for tcm_vhost, a Vhost level TCM
> fabric driver for virtio SCSI initiators into KVM guest.
> 
> This code is currently up and running on v3.5-rc2 host+guest along
> with the virtio-scsi vdev->scan() patch to allow a proper
> scsi_scan_host() to occur once the tcm_vhost nexus has been established
> by the paravirtualized virtio-scsi client here:
> 
> virtio-scsi: Add vdrv->scan for post VIRTIO_CONFIG_S_DRIVER_OK LUN scanning
> http://marc.info/?l=linux-scsi&m=134160609212542&w=2
> 
> Using tcm_vhost requires Zhi's -> Stefan's qemu vhost-scsi tree here:
> 
> https://github.com/wuzhy/qemu/tree/vhost-scsi
> 
> along with the recent QEMU patch to hw/virtio-scsi.c to set max_target=0
> during vhost-scsi operation.
> 
> Changelog v2 -> v3:
> 
>   Unlock on error in tcm_vhost_drop_nexus() (DanC)
>   Fix strlen() doesn't count the terminator (DanC)
>   Call kfree() on an error path (DanC)
>   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
>   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
>   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
>   as requested by MST (nab)
> 
> Changelog v1 -> v2:
> 
>   Fix tv_cmd completion -> release SGL memory leak (nab)
>   Fix sparse warnings for static variable usage ((Fengguang Wu)
>   Fix sparse warnings for min() typing + printk format specs (Fengguang Wu)
>   Convert to cmwq submission for I/O dispatch (nab + hch)
> 
> Changelog v0 -> v1:
> 
>   Merge into single source + header file, and move to drivers/vhost/
> 
> Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>  drivers/staging/Kconfig       |    2 +
>  drivers/vhost/Makefile        |    2 +
>  drivers/vhost/tcm/Kconfig     |    6 +
>  drivers/vhost/tcm/Makefile    |    1 +
>  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
>  drivers/vhost/tcm/tcm_vhost.h |   74 ++
>  6 files changed, 1696 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/vhost/tcm/Kconfig
>  create mode 100644 drivers/vhost/tcm/Makefile
>  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
>  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> 

Really sorry about making you run around like that,
I did not mean moving all of tcm to a directory,
just adding tcm/Kconfig or adding drivers/vhost/Kconfig.tcm
because eventually it's easier to keep it all together
in one place.

> diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
> index 05e33c7..8d1a627 100644
> --- a/drivers/staging/Kconfig
> +++ b/drivers/staging/Kconfig
> @@ -132,4 +132,6 @@ source "drivers/staging/ipack/Kconfig"
>  
>  source "drivers/staging/gdm72xx/Kconfig"
>  
> +source "drivers/vhost/tcm/Kconfig"
> +
>  endif # STAGING
> diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
> index 72dd020..3408bea 100644
> --- a/drivers/vhost/Makefile
> +++ b/drivers/vhost/Makefile
> @@ -1,2 +1,4 @@
>  obj-$(CONFIG_VHOST_NET) += vhost_net.o
>  vhost_net-y := vhost.o net.o
> +
> +obj-$(CONFIG_TCM_VHOST) += tcm/
> diff --git a/drivers/vhost/tcm/Kconfig b/drivers/vhost/tcm/Kconfig
> new file mode 100644
> index 0000000..a9c6f76
> --- /dev/null
> +++ b/drivers/vhost/tcm/Kconfig
> @@ -0,0 +1,6 @@
> +config TCM_VHOST
> +	tristate "TCM_VHOST fabric module (EXPERIMENTAL)"
> +	depends on TARGET_CORE && EVENTFD && EXPERIMENTAL && m
> +	default n
> +	---help---
> +	Say M here to enable the TCM_VHOST fabric module for use with virtio-scsi guests
> diff --git a/drivers/vhost/tcm/Makefile b/drivers/vhost/tcm/Makefile
> new file mode 100644
> index 0000000..54b0ea6
> --- /dev/null
> +++ b/drivers/vhost/tcm/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_TCM_VHOST) += tcm_vhost.o
> diff --git a/drivers/vhost/tcm/tcm_vhost.c b/drivers/vhost/tcm/tcm_vhost.c
> new file mode 100644
> index 0000000..0ee4046
> --- /dev/null
> +++ b/drivers/vhost/tcm/tcm_vhost.c
> @@ -0,0 +1,1611 @@
> +/*******************************************************************************
> + * Vhost kernel TCM fabric driver for virtio SCSI initiators
> + *
> + * (C) Copyright 2010-2012 RisingTide Systems LLC.
> + * (C) Copyright 2010-2012 IBM Corp.
> + *
> + * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
> + *
> + * Authors: Nicholas A. Bellinger <nab@risingtidesystems.com>
> + *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + ****************************************************************************/
> +
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <generated/utsrelease.h>
> +#include <linux/utsname.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/kthread.h>
> +#include <linux/types.h>
> +#include <linux/string.h>
> +#include <linux/configfs.h>
> +#include <linux/ctype.h>
> +#include <linux/compat.h>
> +#include <linux/eventfd.h>
> +#include <linux/vhost.h>
> +#include <linux/fs.h>
> +#include <linux/miscdevice.h>
> +#include <asm/unaligned.h>
> +#include <scsi/scsi.h>
> +#include <scsi/scsi_tcq.h>
> +#include <target/target_core_base.h>
> +#include <target/target_core_fabric.h>
> +#include <target/target_core_fabric_configfs.h>
> +#include <target/target_core_configfs.h>
> +#include <target/configfs_macros.h>
> +#include <linux/vhost.h>
> +#include <linux/virtio_net.h> /* TODO vhost.h currently depends on this */
> +#include <linux/virtio_scsi.h>
> +
> +#include "../vhost.c"
> +#include "../vhost.h"
> +#include "tcm_vhost.h"
> +
> +struct vhost_scsi {
> +	atomic_t vhost_ref_cnt;
> +	struct tcm_vhost_tpg *vs_tpg;
> +	struct vhost_dev dev;
> +	struct vhost_virtqueue vqs[3];

Pls add enum with names for VQs, don't use vqs[3], vqs[2] etc ...

> +
> +	struct vhost_work vs_completion_work; /* cmd completion work item */
> +	struct list_head vs_completion_list;  /* cmd completion queue */
> +	spinlock_t vs_completion_lock;        /* protects s_completion_list */

You mean vs_completion_list?

> +};
> +
> +/* Local pointer to allocated TCM configfs fabric module */
> +static struct target_fabric_configfs *tcm_vhost_fabric_configfs;
> +
> +static struct workqueue_struct *tcm_vhost_workqueue;

BTW why are you using a dedicated wq and not just schedule_work etc?
Probably worth a comment.

> +
> +/* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */
> +static DEFINE_MUTEX(tcm_vhost_mutex);
> +static LIST_HEAD(tcm_vhost_list);
> +
> +static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static int tcm_vhost_check_false(struct se_portal_group *se_tpg)
> +{
> +	return 0;
> +}
> +
> +static char *tcm_vhost_get_fabric_name(void)
> +{
> +	return "vhost";
> +}
> +
> +static u8 tcm_vhost_get_fabric_proto_ident(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_fabric_proto_ident(se_tpg);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_fabric_proto_ident(se_tpg);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_fabric_proto_ident(se_tpg);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_fabric_proto_ident(se_tpg);

This last return is in default: case? So maybe move it there.

> +}
> +
> +static char *tcm_vhost_get_fabric_wwn(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	return &tport->tport_name[0];
> +}
> +
> +static u16 tcm_vhost_get_tag(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	return tpg->tport_tpgt;
> +}
> +
> +static u32 tcm_vhost_get_default_depth(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static u32 tcm_vhost_get_pr_transport_id(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl,
> +	struct t10_pr_registration *pr_reg,
> +	int *format_code,
> +	unsigned char *buf)

I prefer a style like

static u32 tcm_vhost_get_pr_transport_id(struct se_portal_group *se_tpg,
					struct se_node_acl *se_nacl,
					struct t10_pr_registration *pr_reg,
					int *format_code,
					unsigned char *buf)

for consistency with the rest of vhost.

> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +					format_code, buf);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
> +			format_code, buf);

This last return is in default: case? So maybe move it there.

> +}
> +
> +static u32 tcm_vhost_get_pr_transport_id_len(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl,
> +	struct t10_pr_registration *pr_reg,
> +	int *format_code)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +					format_code);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
> +			format_code);

This last return is in default: case? So maybe move it there.

> +}
> +
> +static char *tcm_vhost_parse_pr_out_transport_id(
> +	struct se_portal_group *se_tpg,
> +	const char *buf,
> +	u32 *out_tid_len,
> +	char **port_nexus_ptr)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport = tpg->tport;
> +
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	case SCSI_PROTOCOL_FCP:
> +		return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	case SCSI_PROTOCOL_ISCSI:
> +		return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +					port_nexus_ptr);
> +	default:
> +		pr_err("Unknown tport_proto_id: 0x%02x, using"
> +			" SAS emulation\n", tport->tport_proto_id);
> +		break;
> +	}
> +
> +	return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
> +			port_nexus_ptr);

This last return is in default: case? So maybe move it there.

> +}
> +
> +static struct se_node_acl *tcm_vhost_alloc_fabric_acl(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_nacl *nacl;
> +
> +	nacl = kzalloc(sizeof(struct tcm_vhost_nacl), GFP_KERNEL);
> +	if (!nacl) {
> +		pr_err("Unable to alocate struct tcm_vhost_nacl\n");
> +		return NULL;
> +	}
> +
> +	return &nacl->se_node_acl;
> +}
> +
> +static void tcm_vhost_release_fabric_acl(
> +	struct se_portal_group *se_tpg,
> +	struct se_node_acl *se_nacl)
> +{
> +	struct tcm_vhost_nacl *nacl = container_of(se_nacl,
> +			struct tcm_vhost_nacl, se_node_acl);
> +	kfree(nacl);
> +}
> +
> +static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg)
> +{
> +	return 1;
> +}
> +
> +static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
> +{
> +	return;
> +}
> +
> +static int tcm_vhost_shutdown_session(struct se_session *se_sess)
> +{
> +	return 0;
> +}
> +
> +static void tcm_vhost_close_session(struct se_session *se_sess)
> +{
> +	return;
> +}
> +
> +static u32 tcm_vhost_sess_get_index(struct se_session *se_sess)
> +{
> +	return 0;
> +}
> +
> +static int tcm_vhost_write_pending(struct se_cmd *se_cmd)
> +{
> +	/* Go ahead and process the write immediately */
> +	target_execute_cmd(se_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_write_pending_status(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static void tcm_vhost_set_default_node_attrs(struct se_node_acl *nacl)
> +{
> +	return;
> +}
> +
> +static u32 tcm_vhost_get_task_tag(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static int tcm_vhost_get_cmd_state(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *);
> +
> +static int tcm_vhost_queue_data_in(struct se_cmd *se_cmd)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
> +				struct tcm_vhost_cmd, tvc_se_cmd);
> +	vhost_scsi_complete_cmd(tv_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_queue_status(struct se_cmd *se_cmd)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
> +				struct tcm_vhost_cmd, tvc_se_cmd);
> +	vhost_scsi_complete_cmd(tv_cmd);
> +	return 0;
> +}
> +
> +static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
> +{
> +	return 0;
> +}
> +
> +static u16 tcm_vhost_set_fabric_sense_len(struct se_cmd *se_cmd, u32 sense_length)
> +{
> +	return 0;
> +}
> +
> +static u16 tcm_vhost_get_fabric_sense_len(void)
> +{
> +	return 0;
> +}
> +
> +static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> +{
> +	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +
> +	/* TODO locking against target/backend threads? */

More a FIXME than a TODO?

> +	transport_generic_free_cmd(se_cmd, 1);
> +
> +	if (tv_cmd->tvc_sgl_count) {
> +		u32 i;
> +		for (i = 0; i < tv_cmd->tvc_sgl_count; i++)

I prefer ++i for consistency with rest of vhost.

> +			put_page(sg_page(&tv_cmd->tvc_sgl[i]));
> +
> +		kfree(tv_cmd->tvc_sgl);
> +	}
> +
> +	kfree(tv_cmd);
> +}
> +
> +/* Dequeue a command from the completion list */
> +static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion(struct vhost_scsi *vs)
> +{
> +	struct tcm_vhost_cmd *tv_cmd = NULL;
> +
> +	spin_lock_bh(&vs->vs_completion_lock);
> +	if (list_empty(&vs->vs_completion_list)) {
> +		spin_unlock_bh(&vs->vs_completion_lock);
> +		return NULL;

Just goto end will be neater IMO.

> +	}
> +
> +	list_for_each_entry(tv_cmd, &vs->vs_completion_list,
> +			    tvc_completion_list) {
> +		list_del(&tv_cmd->tvc_completion_list);
> +		break;
> +	}
> +	spin_unlock_bh(&vs->vs_completion_lock);
> +	return tv_cmd;
> +}
> +
> +/* Fill in status and signal that we are done processing this command
> + *
> + * This is scheduled in the vhost work queue so we are called with the owner
> + * process mm and can access the vring.
> + */
> +static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
> +{
> +	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
> +	                                     vs_completion_work);
> +	struct tcm_vhost_cmd *tv_cmd;
> +
> +	while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs)) != NULL) {

I prefer without != NULL for consistency with other vhost drivers.

> +		struct virtio_scsi_cmd_resp v_rsp;
> +		struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +		int ret;
> +
> +		pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
> +			tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);
> +
> +		memset(&v_rsp, 0, sizeof(v_rsp));

I prefer argument of sizeof without () if it's a variable for
consistency with rest of vhost.

> +		v_rsp.resid = se_cmd->residual_count;
> +		/* TODO is status_qualifier field needed? */
> +		v_rsp.status = se_cmd->scsi_status;
> +		v_rsp.sense_len = se_cmd->scsi_sense_length;
> +		memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,
> +		       v_rsp.sense_len);
> +		ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));

I prefer argument of sizeof without () if it's a variable for
consistency with rest of vhost.

> +		if (likely(ret == 0))

I prefer without == 0, !ret, for consistency with other vhost drivers.

> +			vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);

Please add enum with symbolic names for the VQS, don't use

> +		else
> +			pr_err("Faulted on virtio_scsi_cmd_resp\n");
> +
> +		vhost_scsi_free_cmd(tv_cmd);
> +	}
> +
> +	vhost_signal(&vs->dev, &vs->vqs[2]);
> +}
> +
> +static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
> +{
> +	struct vhost_scsi *vs = tv_cmd->tvc_vhost;
> +
> +	pr_debug("%s tv_cmd %p\n", __func__, tv_cmd);
> +
> +	spin_lock_bh(&vs->vs_completion_lock);
> +	list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list);
> +	spin_unlock_bh(&vs->vs_completion_lock);
> +
> +	vhost_work_queue(&vs->dev, &vs->vs_completion_work);
> +}
> +
> +static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
> +	struct tcm_vhost_tpg *tv_tpg,
> +	struct virtio_scsi_cmd_req *v_req,
> +	u32 exp_data_len,
> +	int data_direction)
> +{
> +	struct tcm_vhost_cmd *tv_cmd;
> +	struct tcm_vhost_nexus *tv_nexus;
> +	struct se_portal_group *se_tpg = &tv_tpg->se_tpg;
> +	struct se_session *se_sess;
> +	struct se_cmd *se_cmd;
> +	int sam_task_attr;
> +
> +	tv_nexus = tv_tpg->tpg_nexus;
> +	if (!tv_nexus) {
> +		pr_err("Unable to locate active struct tcm_vhost_nexus\n");
> +		return ERR_PTR(-EIO);
> +	}
> +	se_sess = tv_nexus->tvn_se_sess;
> +
> +	tv_cmd = kzalloc(sizeof(struct tcm_vhost_cmd), GFP_ATOMIC);

Would prefer kmalloc + explicit initialization of all fields to be consistent
with the rest of vhost.

> +	if (!tv_cmd) {
> +		pr_err("Unable to allocate struct tcm_vhost_cmd\n");

Do we recover from this error?
We should. GFP_ATOMIC can fail and it is not
a good idea to invoke pr_err when it does.

> +		return ERR_PTR(-ENOMEM);
> +	}
> +	INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
> +	tv_cmd->tvc_tag = v_req->tag;
> +
> +	se_cmd = &tv_cmd->tvc_se_cmd;
> +	/*
> +	 * Locate the SAM Task Attr from virtio_scsi_cmd_req
> +	 */
> +	sam_task_attr = v_req->task_attr;
> +	/*
> +	 * Initialize struct se_cmd descriptor from target_core_mod infrastructure
> +	 */
> +	transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, exp_data_len,
> +				data_direction, sam_task_attr,
> +				&tv_cmd->tvc_sense_buf[0]);
> +
> +#if 0	/* FIXME: vhost_scsi_allocate_cmd() BIDI operation */
> +	if (bidi)
> +		se_cmd->se_cmd_flags |= SCF_BIDI;
> +#endif
> +	return tv_cmd;
> +}
> +
> +/*
> + * Map a user memory range into a scatterlist
> + *
> + * Returns the number of scatterlist entries used or -errno on error.
> + */
> +static int vhost_scsi_map_to_sgl(struct scatterlist *sgl,
> +		                 unsigned int sgl_count,
> +		                 void __user *ptr, size_t len, int write)
> +{
> +	struct scatterlist *sg = sgl;
> +	unsigned int npages = 0;
> +	int ret;
> +
> +	while (len > 0) {
> +		struct page *page;
> +		unsigned int offset = (uintptr_t)ptr & ~PAGE_MASK;
> +		unsigned int nbytes = min_t(unsigned int,
> +				PAGE_SIZE - offset, len);
> +
> +		if (npages == sgl_count) {
> +			ret = -ENOBUFS;
> +			goto err;
> +		}
> +
> +		ret = get_user_pages_fast((unsigned long)ptr, 1, write, &page);
> +		BUG_ON(ret == 0); /* we should either get our page or fail */
> +		if (ret < 0)
> +			goto err;
> +
> +		sg_set_page(sg, page, nbytes, offset);
> +		ptr += nbytes;
> +		len -= nbytes;
> +		sg++;
> +		npages++;
> +	}
> +	return npages;
> +
> +err:
> +	/* Put pages that we hold */
> +	for (sg = sgl; sg != &sgl[npages]; sg++)
> +		put_page(sg_page(sg));
> +	return ret;
> +}
> +
> +static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd,
> +                                     struct iovec *iov, unsigned int niov,
> +				     int write)
> +{
> +	int ret;
> +	unsigned int i;
> +	u32 sgl_count;
> +	struct scatterlist *sg;
> +
> +	/*
> +	 * Find out how long sglist needs to be
> +	 */
> +	sgl_count = 0;
> +	for (i = 0; i < niov; i++) {
> +		sgl_count += (((uintptr_t)iov[i].iov_base + iov[i].iov_len +
> +		             PAGE_SIZE - 1) >> PAGE_SHIFT) -
> +		             ((uintptr_t)iov[i].iov_base >> PAGE_SHIFT);
> +	}
> +	/* TODO overflow checking */
> +
> +	sg = kmalloc(sizeof(tv_cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
> +	if (!sg)
> +		return -ENOMEM;
> +	pr_debug("%s sg %p sgl_count %u is_err %ld\n", __func__,
> +	       sg, sgl_count, IS_ERR(sg));
> +	sg_init_table(sg, sgl_count);
> +
> +	tv_cmd->tvc_sgl = sg;
> +	tv_cmd->tvc_sgl_count = sgl_count;
> +
> +	pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
> +	for (i = 0; i < niov; i++) {
> +		ret = vhost_scsi_map_to_sgl(sg, sgl_count, iov[i].iov_base,
> +		                            iov[i].iov_len, write);
> +		if (ret < 0) {
> +			for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
> +				put_page(sg_page(&tv_cmd->tvc_sgl[i]));
> +			kfree(tv_cmd->tvc_sgl);
> +			tv_cmd->tvc_sgl = NULL;
> +			tv_cmd->tvc_sgl_count = 0;
> +			return ret;
> +		}
> +
> +		sg += ret;
> +		sgl_count -= ret;
> +	}
> +	return 0;
> +}
> +
> +static void tcm_vhost_submission_work(struct work_struct *work)
> +{
> +	struct tcm_vhost_cmd *tv_cmd =
> +		container_of(work, struct tcm_vhost_cmd, work);
> +	struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
> +	struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
> +	int rc, sg_no_bidi = 0;
> +	/*
> +	 * Locate the struct se_lun pointer based on v_req->lun, and
> +	 * attach it to struct se_cmd
> +	 */
> +	rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, tv_cmd->tvc_lun);
> +	if (rc < 0) {
> +		pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun);
> +		transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd,
> +			tv_cmd->tvc_se_cmd.scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +
> +	rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb);
> +	if (rc == -ENOMEM) {
> +		transport_send_check_condition_and_sense(se_cmd,
> +				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	} else if (rc < 0) {
> +		if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
> +			tcm_vhost_queue_status(se_cmd);
> +		else
> +			transport_send_check_condition_and_sense(se_cmd,
> +					se_cmd->scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +
> +	if (tv_cmd->tvc_sgl_count) {
> +		sg_ptr = tv_cmd->tvc_sgl;
> +		/*
> +		 * For BIDI commands, pass in the extra READ buffer
> +		 * to transport_generic_map_mem_to_cmd() below..
> +		 */
> +/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */
> +#if 0
> +		if (se_cmd->se_cmd_flags & SCF_BIDI) {
> +			sg_bidi_ptr = NULL;
> +			sg_no_bidi = 0;
> +		}
> +#endif
> +	} else {
> +		sg_ptr = NULL;
> +	}
> +
> +	rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr,
> +				tv_cmd->tvc_sgl_count, sg_bidi_ptr,
> +				sg_no_bidi);
> +	if (rc < 0) {
> +		transport_send_check_condition_and_sense(se_cmd,
> +				se_cmd->scsi_sense_reason, 0);
> +		transport_generic_free_cmd(se_cmd, 0);
> +		return;
> +	}
> +	transport_handle_cdb_direct(se_cmd);
> +}
> +
> +static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
> +{
> +	struct vhost_virtqueue *vq = &vs->vqs[2];
> +	struct virtio_scsi_cmd_req v_req;
> +	struct tcm_vhost_tpg *tv_tpg;
> +	struct tcm_vhost_cmd *tv_cmd;
> +	u32 exp_data_len, data_first, data_num, data_direction;
> +	unsigned out, in, i;
> +	int head, ret;
> +
> +	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
> +	tv_tpg = vs->vs_tpg;
> +	if (unlikely(!tv_tpg)) {
> +		pr_err("%s endpoint not set\n", __func__);
> +		return;
> +	}
> +
> +	mutex_lock(&vq->mutex);
> +	vhost_disable_notify(&vs->dev, vq);
> +
> +	for (;;) {
> +		head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
> +					ARRAY_SIZE(vq->iov), &out, &in,
> +					NULL, NULL);
> +		pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n", head, out, in);
> +		/* On error, stop handling until the next kick. */
> +		if (unlikely(head < 0))
> +			break;
> +		/* Nothing new?  Wait for eventfd to tell us they refilled. */
> +		if (head == vq->num) {
> +			if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
> +				vhost_disable_notify(&vs->dev, vq);
> +				continue;
> +			}
> +			break;
> +		}
> +
> +/* FIXME: BIDI operation */
> +		if (out == 1 && in == 1) {
> +			data_direction = DMA_NONE;
> +			data_first = 0;
> +			data_num = 0;
> +		} else if (out == 1 && in > 1) {
> +			data_direction = DMA_FROM_DEVICE;
> +			data_first = out + 1;
> +			data_num = in - 1;
> +		} else if (out > 1 && in == 1) {
> +			data_direction = DMA_TO_DEVICE;
> +			data_first = 1;
> +			data_num = out - 1;
> +		} else {
> +			pr_err("Invalid buffer layout out: %u in: %u\n", out, in);
> +			break;
> +		}
> +
> +		/*
> +		 * Check for a sane resp buffer so we can report errors to
> +		 * the guest.
> +		 */
> +		if (unlikely(vq->iov[out].iov_len !=
> +					sizeof(struct virtio_scsi_cmd_resp))) {
> +			pr_err("Expecting virtio_scsi_cmd_resp, got %zu bytes\n",
> +					vq->iov[out].iov_len);
> +			break;
> +		}
> +
> +		if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
> +			pr_err("Expecting virtio_scsi_cmd_req, got %zu bytes\n",
> +					vq->iov[0].iov_len);
> +			break;
> +		}

Are these spec requirements?
virtio spec generally does not to require specific layout from guests.
For example it might be better for guest to combine
bufs together. So better to use memcpy_from_iovec etc.
did not yet check virtio scsi spec specifically maybe it is different?

Also use vq_err so userspace can detect errors.
Also pr_error on buggy userspace is a DOS potential.


> +		pr_debug("Calling __copy_from_user: vq->iov[0].iov_base: %p, len: %zu\n",
> +				vq->iov[0].iov_base, sizeof(v_req));

I think most of these pr_debug should go. They won't be helpful in
production.

> +		ret = __copy_from_user(&v_req, vq->iov[0].iov_base, sizeof(v_req));
> +		if (unlikely(ret)) {
> +			pr_err("Faulted on virtio_scsi_cmd_req\n");
> +			break;
> +		}
> +
> +		exp_data_len = 0;
> +		for (i = 0; i < data_num; i++) {


++i pls

> +			exp_data_len += vq->iov[data_first + i].iov_len;
> +		}


Don't do {} for single line loops pls.

> +
> +		tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
> +					exp_data_len, data_direction);
> +		if (IS_ERR(tv_cmd)) {
> +			pr_err("vhost_scsi_allocate_cmd failed %ld\n", PTR_ERR(tv_cmd));
> +			break;

Looks like a bug. If we run out of GFP_ATOMIC we just stop processing
the vq?

> +		}
> +		pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction: %d\n",
> +				tv_cmd, exp_data_len, data_direction);
> +

This probably prints too much if debug is enabled.

> +		tv_cmd->tvc_vhost = vs;
> +
> +		if (unlikely(vq->iov[out].iov_len !=
> +		             sizeof(struct virtio_scsi_cmd_resp))) {
> +			pr_err("Expecting virtio_scsi_cmd_resp, "
> +			       " got %zu bytes, out: %d, in: %d\n", vq->iov[out].iov_len, out, in);
> +			break;

Should be vq_err so userspace can detect an error and recover.

> +		}
> +
> +		tv_cmd->tvc_resp = vq->iov[out].iov_base;
> +
> +		/*
> +		 * Copy in the recieved CDB descriptor into tv_cmd->tvc_cdb
> +		 * that will be used by tcm_vhost_new_cmd_map() and down into
> +		 * target_setup_cmd_from_cdb()
> +		 */
> +		memcpy(tv_cmd->tvc_cdb, v_req.cdb, TCM_VHOST_MAX_CDB_SIZE);
> +		/*
> +		 * Check that the recieved CDB size does not exceeded our

typo


> +		 * hardcoded max for tcm_vhost
> +		 */
> +		/* TODO what if cdb was too small for varlen cdb header? */
> +		if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) > TCM_VHOST_MAX_CDB_SIZE)) {
> +			pr_err("Received SCSI CDB with command_size: %d that exceeds"
> +				" SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
> +				scsi_command_size(tv_cmd->tvc_cdb), TCM_VHOST_MAX_CDB_SIZE);
> +			break; /* TODO */
> +		}
> +		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
> +
> +		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
> +			tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);

This probably prints too much if debug is enabled.

> +
> +		if (data_direction != DMA_NONE) {
> +			ret = vhost_scsi_map_iov_to_sgl(tv_cmd, &vq->iov[data_first],
> +					data_num, data_direction == DMA_TO_DEVICE);
> +			if (unlikely(ret)) {
> +				pr_err("Failed to map iov to sgl\n");

vq_err?

> +				break; /* TODO */
> +			}
> +		}
> +
> +		/*
> +		 * Save the descriptor from vhost_get_vq_desc() to be used to
> +		 * complete the virtio-scsi request in TCM callback context via
> +		 * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
> +		 */
> +		tv_cmd->tvc_vq_desc = head;
> +		/*
> +		 * Dispatch tv_cmd descriptor for cmwq execution in process
> +		 * context provided by tcm_vhost_workqueue.  This also ensures
> +		 * tv_cmd is executed on the same kworker CPU as this vhost
> +		 * thread to gain positive L2 cache locality effects..
> +		 */
> +		INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
> +		queue_work(tcm_vhost_workqueue, &tv_cmd->work);
> +	}
> +
> +	mutex_unlock(&vq->mutex);
> +}
> +
> +static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
> +{
> +     pr_err("%s: The handling func for control queue.\n", __func__);
> +}
> +
> +static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
> +{
> +     pr_err("%s: The handling func for event queue.\n", __func__);
> +}
> +

Above looks strange. Pls add some comments why these are empty.
Normally kicks are guest triggerable. Don't pr_err.

> +static void vhost_scsi_handle_kick(struct vhost_work *work)
> +{
> +	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> +						poll.work);
> +	struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
> +
> +	vhost_scsi_handle_vq(vs);
> +}
> +
> +/*
> + * Called from vhost_scsi_ioctl() context to walk the list of available tcm_vhost_tpg
> + * with an active struct tcm_vhost_nexus
> + */
> +static int vhost_scsi_set_endpoint(
> +	struct vhost_scsi *vs,
> +	struct vhost_vring_target *t)
> +{
> +	struct tcm_vhost_tport *tv_tport;
> +	struct tcm_vhost_tpg *tv_tpg;
> +        int index;

don't indent with spaces

> +
> +	mutex_lock(&vs->dev.mutex);
> +	/* Verify that ring has been setup correctly. */
> +	for (index = 0; index < vs->dev.nvqs; ++index) {
> +		/* Verify that ring has been setup correctly. */
> +		if (!vhost_vq_access_ok(&vs->vqs[index])) {
> +		        mutex_unlock(&vs->dev.mutex);
> +			return -EFAULT;
> +		}
> +	}
> +
> +	if (vs->vs_tpg) {
> +		mutex_unlock(&vs->dev.mutex);
> +		return -EEXIST;
> +	}
> +	mutex_unlock(&vs->dev.mutex);
> +
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
> +		mutex_lock(&tv_tpg->tv_tpg_mutex);
> +		if (!tv_tpg->tpg_nexus) {
> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			continue;
> +		}
> +		if (atomic_read(&tv_tpg->tv_tpg_vhost_count)) {

what's the story with this counter? What are the rules?
It can be changed after the read here, can't it?
Pls document.

> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			continue;
> +		}

way cleaner with goto.

> +		tv_tport = tv_tpg->tport;
> +
> +		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
> +		    (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
> +			atomic_inc(&tv_tpg->tv_tpg_vhost_count);
> +			smp_mb__after_atomic_inc();
> +			mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +			mutex_unlock(&tcm_vhost_mutex);
> +
> +			mutex_lock(&vs->dev.mutex);
> +			vs->vs_tpg = tv_tpg;
> +			atomic_inc(&vs->vhost_ref_cnt);
> +			smp_mb__after_atomic_inc();
> +			mutex_unlock(&vs->dev.mutex);
> +			return 0;
> +		}
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +	}
> +	mutex_unlock(&tcm_vhost_mutex);
> +	return -EINVAL;

Will be cleaner with gotos to exit loops and handle errors.

> +}
> +
> +static int vhost_scsi_clear_endpoint(
> +	struct vhost_scsi *vs,
> +	struct vhost_vring_target *t)
> +{
> +	struct tcm_vhost_tport *tv_tport;
> +	struct tcm_vhost_tpg *tv_tpg;
> +        int index;
> +
> +	mutex_lock(&vs->dev.mutex);
> +	/* Verify that ring has been setup correctly. */
> +	for (index = 0; index < vs->dev.nvqs; ++index) {
> +		if (!vhost_vq_access_ok(&vs->vqs[index])) {
> +		        mutex_unlock(&vs->dev.mutex);
> +			return -EFAULT;
> +		}
> +	}
> +
> +	if (!vs->vs_tpg) {
> +		mutex_unlock(&vs->dev.mutex);
> +		return -ENODEV;
> +	}
> +	tv_tpg = vs->vs_tpg;
> +	tv_tport = tv_tpg->tport;
> +
> +	if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
> +	    (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
> +		mutex_unlock(&vs->dev.mutex);
> +		pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
> +			" does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
> +			tv_tport->tport_name, tv_tpg->tport_tpgt,
> +			t->vhost_wwpn, t->vhost_tpgt);
> +		return -EINVAL;
> +	}
> +        atomic_dec(&tv_tpg->tv_tpg_vhost_count);

don't indent with spaces.

> +	vs->vs_tpg = NULL;
> +	mutex_unlock(&vs->dev.mutex);
> +
> +	return 0;
> +}
> +
> +static int vhost_scsi_open(struct inode *inode, struct file *f)
> +{
> +	struct vhost_scsi *s;
> +	int r;
> +
> +	s = kzalloc(sizeof(*s), GFP_KERNEL);
> +	if (!s)
> +		return -ENOMEM;
> +
> +	vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
> +	INIT_LIST_HEAD(&s->vs_completion_list);
> +	spin_lock_init(&s->vs_completion_lock);
> +
> +	s->vqs[0].handle_kick = vhost_scsi_ctl_handle_kick;
> +	s->vqs[1].handle_kick = vhost_scsi_evt_handle_kick;
> +	s->vqs[2].handle_kick = vhost_scsi_handle_kick;
> +	r = vhost_dev_init(&s->dev, s->vqs, 3);
> +	if (r < 0) {
> +		kfree(s);
> +		return r;
> +	}
> +
> +	f->private_data = s;
> +	return 0;
> +}
> +
> +static int vhost_scsi_release(struct inode *inode, struct file *f)
> +{
> +	struct vhost_scsi *s = f->private_data;
> +
> +        if (s->vs_tpg && s->vs_tpg->tport) {
> +            struct vhost_vring_target backend;
> +            memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name, sizeof(backend.vhost_wwpn));
> +            backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
> +            vhost_scsi_clear_endpoint(s, &backend);
> +        }
> +
> +	vhost_dev_cleanup(&s->dev, false);
> +	kfree(s);
> +	return 0;
> +}
> +
> +static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> +{
> +	if (features & ~VHOST_FEATURES)
> +		return -EOPNOTSUPP;
> +
> +	mutex_lock(&vs->dev.mutex);
> +	if ((features & (1 << VHOST_F_LOG_ALL)) &&
> +	    !vhost_log_access_ok(&vs->dev)) {
> +		mutex_unlock(&vs->dev.mutex);
> +		return -EFAULT;
> +	}
> +	vs->dev.acked_features = features;
> +	/* TODO possibly smp_wmb() and flush vqs */
> +	mutex_unlock(&vs->dev.mutex);
> +	return 0;
> +}
> +
> +static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
> +				unsigned long arg)
> +{
> +	struct vhost_scsi *vs = f->private_data;
> +	struct vhost_vring_target backend;
> +	void __user *argp = (void __user *)arg;
> +	u64 __user *featurep = argp;
> +	u64 features;
> +	int r;
> +
> +	switch (ioctl) {
> +	case VHOST_SCSI_SET_ENDPOINT:
> +		if (copy_from_user(&backend, argp, sizeof backend))
> +			return -EFAULT;
> +
> +		return vhost_scsi_set_endpoint(vs, &backend);
> +	case VHOST_SCSI_CLEAR_ENDPOINT:
> +		if (copy_from_user(&backend, argp, sizeof backend))
> +			return -EFAULT;
> +
> +		return vhost_scsi_clear_endpoint(vs, &backend);
> +	case VHOST_GET_FEATURES:
> +		features = VHOST_FEATURES;
> +		if (copy_to_user(featurep, &features, sizeof features))
> +			return -EFAULT;
> +		return 0;
> +	case VHOST_SET_FEATURES:
> +		if (copy_from_user(&features, featurep, sizeof features))
> +			return -EFAULT;
> +		return vhost_scsi_set_features(vs, features);
> +	default:
> +		mutex_lock(&vs->dev.mutex);
> +		r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
> +		mutex_unlock(&vs->dev.mutex);
> +		return r;
> +	}
> +}
> +
> +static const struct file_operations vhost_scsi_fops = {
> +	.owner          = THIS_MODULE,
> +	.release        = vhost_scsi_release,
> +	.unlocked_ioctl = vhost_scsi_ioctl,
> +	/* TODO compat ioctl? */

Why not?

> +	.open           = vhost_scsi_open,
> +	.llseek		= noop_llseek,
> +};
> +
> +static struct miscdevice vhost_scsi_misc = {
> +	MISC_DYNAMIC_MINOR,
> +	"vhost-scsi",
> +	&vhost_scsi_fops,
> +};
> +
> +static int __init vhost_scsi_register(void)
> +{
> +	return misc_register(&vhost_scsi_misc);
> +}
> +
> +static int vhost_scsi_deregister(void)
> +{
> +	return misc_deregister(&vhost_scsi_misc);
> +}
> +
> +static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
> +{
> +	switch (tport->tport_proto_id) {
> +	case SCSI_PROTOCOL_SAS:
> +		return "SAS";
> +	case SCSI_PROTOCOL_FCP:
> +		return "FCP";
> +	case SCSI_PROTOCOL_ISCSI:
> +		return "iSCSI";
> +	default:
> +		break;
> +	}
> +
> +	return "Unknown";
> +}
> +
> +static int tcm_vhost_port_link(
> +	struct se_portal_group *se_tpg,
> +	struct se_lun *lun)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	atomic_inc(&tv_tpg->tv_tpg_port_count);
> +	smp_mb__after_atomic_inc();
> +
> +	return 0;
> +}
> +
> +static void tcm_vhost_port_unlink(
> +	struct se_portal_group *se_tpg,
> +	struct se_lun *se_lun)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	atomic_dec(&tv_tpg->tv_tpg_port_count);
> +	smp_mb__after_atomic_dec();
> +}
> +
> +static struct se_node_acl *tcm_vhost_make_nodeacl(
> +	struct se_portal_group *se_tpg,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct se_node_acl *se_nacl, *se_nacl_new;
> +	struct tcm_vhost_nacl *nacl;
> +	u64 wwpn = 0;
> +	u32 nexus_depth;
> +
> +	/* tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
> +		return ERR_PTR(-EINVAL); */


why is it here?

> +	se_nacl_new = tcm_vhost_alloc_fabric_acl(se_tpg);
> +	if (!se_nacl_new)
> +		return ERR_PTR(-ENOMEM);
> +//#warning FIXME: Hardcoded nexus depth in tcm_vhost_make_nodeacl()

Don't use this style for comments pls.

> +	nexus_depth = 1;
> +	/*
> +	 * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
> +	 * when converting a NodeACL from demo mode -> explict
> +	 */
> +	se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
> +				name, nexus_depth);
> +	if (IS_ERR(se_nacl)) {
> +		tcm_vhost_release_fabric_acl(se_tpg, se_nacl_new);
> +		return se_nacl;
> +	}
> +	/*
> +	 * Locate our struct tcm_vhost_nacl and set the FC Nport WWPN
> +	 */
> +	nacl = container_of(se_nacl, struct tcm_vhost_nacl, se_node_acl);
> +	nacl->iport_wwpn = wwpn;
> +	/* tcm_vhost_format_wwn(&nacl->iport_name[0], TCM_VHOST_NAMELEN, wwpn); */
> +
> +	return se_nacl;
> +}
> +
> +static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
> +{
> +	struct tcm_vhost_nacl *nacl = container_of(se_acl,
> +				struct tcm_vhost_nacl, se_node_acl);
> +	core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
> +	kfree(nacl);
> +}
> +
> +static int tcm_vhost_make_nexus(
> +	struct tcm_vhost_tpg *tv_tpg,
> +	const char *name)
> +{
> +	struct se_portal_group *se_tpg;
> +	struct tcm_vhost_nexus *tv_nexus;
> +
> +	mutex_lock(&tv_tpg->tv_tpg_mutex);
> +	if (tv_tpg->tpg_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_debug("tv_tpg->tpg_nexus already exists\n");
> +		return -EEXIST;
> +	}
> +	se_tpg = &tv_tpg->se_tpg;
> +
> +	tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
> +	if (!tv_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_err("Unable to allocate struct tcm_vhost_nexus\n");
> +		return -ENOMEM;
> +	}
> +	/*
> +	 *  Initialize the struct se_session pointer
> +	 */
> +	tv_nexus->tvn_se_sess = transport_init_session();
> +	if (IS_ERR(tv_nexus->tvn_se_sess)) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		kfree(tv_nexus);
> +		return -ENOMEM;
> +	}
> +	/*
> +	 * Since we are running in 'demo mode' this call with generate a
> +	 * struct se_node_acl for the tcm_vhost struct se_portal_group with
> +	 * the SCSI Initiator port name of the passed configfs group 'name'.
> +	 */
> +	tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
> +				se_tpg, (unsigned char *)name);
> +	if (!tv_nexus->tvn_se_sess->se_node_acl) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		pr_debug("core_tpg_check_initiator_node_acl() failed"
> +				" for %s\n", name);
> +		transport_free_session(tv_nexus->tvn_se_sess);
> +		kfree(tv_nexus);
> +		return -ENOMEM;
> +	}
> +	/*
> +	 * Now register the TCM vHost virtual I_T Nexus as active with the
> +	 * call to __transport_register_session()
> +	 */
> +	__transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
> +			tv_nexus->tvn_se_sess, tv_nexus);
> +	tv_tpg->tpg_nexus = tv_nexus;
> +
> +	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +	return 0;
> +}
> +
> +static int tcm_vhost_drop_nexus(
> +	struct tcm_vhost_tpg *tpg)
> +{
> +	struct se_session *se_sess;
> +	struct tcm_vhost_nexus *tv_nexus;
> +
> +	mutex_lock(&tpg->tv_tpg_mutex);
> +	tv_nexus = tpg->tpg_nexus;
> +	if (!tv_nexus) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		return -ENODEV;
> +	}
> +
> +	se_sess = tv_nexus->tvn_se_sess;
> +	if (!se_sess) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		return -ENODEV;
> +	}
> +
> +	if (atomic_read(&tpg->tv_tpg_port_count)) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		pr_err("Unable to remove TCM_vHost I_T Nexus with"
> +			" active TPG port count: %d\n",
> +			atomic_read(&tpg->tv_tpg_port_count));
> +		return -EPERM;
> +	}
> +
> +	if (atomic_read(&tpg->tv_tpg_vhost_count)) {
> +		mutex_unlock(&tpg->tv_tpg_mutex);
> +		pr_err("Unable to remove TCM_vHost I_T Nexus with"
> +			" active TPG vhost count: %d\n",
> +			atomic_read(&tpg->tv_tpg_vhost_count));
> +		return -EPERM;
> +	}
> +
> +	pr_debug("TCM_vHost_ConfigFS: Removing I_T Nexus to emulated"
> +		" %s Initiator Port: %s\n", tcm_vhost_dump_proto_id(tpg->tport),
> +		tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
> +	/*
> +	 * Release the SCSI I_T Nexus to the emulated vHost Target Port
> +	 */
> +	transport_deregister_session(tv_nexus->tvn_se_sess);
> +	tpg->tpg_nexus = NULL;
> +	mutex_unlock(&tpg->tv_tpg_mutex);
> +
> +	kfree(tv_nexus);
> +	return 0;
> +}
> +
> +static ssize_t tcm_vhost_tpg_show_nexus(
> +	struct se_portal_group *se_tpg,
> +	char *page)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_nexus *tv_nexus;
> +	ssize_t ret;
> +
> +	mutex_lock(&tv_tpg->tv_tpg_mutex);
> +	tv_nexus = tv_tpg->tpg_nexus;
> +	if (!tv_nexus) {
> +		mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +		return -ENODEV;
> +	}
> +	ret = snprintf(page, PAGE_SIZE, "%s\n",
> +			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
> +	mutex_unlock(&tv_tpg->tv_tpg_mutex);
> +
> +	return ret;
> +}
> +
> +static ssize_t tcm_vhost_tpg_store_nexus(
> +	struct se_portal_group *se_tpg,
> +	const char *page,
> +	size_t count)
> +{
> +	struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +	struct tcm_vhost_tport *tport_wwn = tv_tpg->tport;
> +	unsigned char i_port[TCM_VHOST_NAMELEN], *ptr, *port_ptr;
> +	int ret;
> +	/*
> +	 * Shutdown the active I_T nexus if 'NULL' is passed..
> +	 */
> +	if (!strncmp(page, "NULL", 4)) {
> +		ret = tcm_vhost_drop_nexus(tv_tpg);
> +		return (!ret) ? count : ret;
> +	}
> +	/*
> +	 * Otherwise make sure the passed virtual Initiator port WWN matches
> +	 * the fabric protocol_id set in tcm_vhost_make_tport(), and call
> +	 * tcm_vhost_make_nexus().
> +	 */
> +	if (strlen(page) >= TCM_VHOST_NAMELEN) {
> +		pr_err("Emulated NAA Sas Address: %s, exceeds"
> +				" max: %d\n", page, TCM_VHOST_NAMELEN);
> +		return -EINVAL;
> +	}
> +	snprintf(&i_port[0], TCM_VHOST_NAMELEN, "%s", page);
> +
> +	ptr = strstr(i_port, "naa.");
> +	if (ptr) {
> +		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
> +			pr_err("Passed SAS Initiator Port %s does not"
> +				" match target port protoid: %s\n", i_port,
> +				tcm_vhost_dump_proto_id(tport_wwn));
> +			return -EINVAL;
> +		}
> +		port_ptr = &i_port[0];
> +		goto check_newline;
> +	}
> +	ptr = strstr(i_port, "fc.");
> +	if (ptr) {
> +		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
> +			pr_err("Passed FCP Initiator Port %s does not"
> +				" match target port protoid: %s\n", i_port,
> +				tcm_vhost_dump_proto_id(tport_wwn));
> +			return -EINVAL;
> +		}
> +		port_ptr = &i_port[3]; /* Skip over "fc." */
> +		goto check_newline;
> +	}
> +	ptr = strstr(i_port, "iqn.");
> +	if (ptr) {
> +		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
> +			pr_err("Passed iSCSI Initiator Port %s does not"
> +				" match target port protoid: %s\n", i_port,
> +				tcm_vhost_dump_proto_id(tport_wwn));
> +			return -EINVAL;
> +		}
> +		port_ptr = &i_port[0];
> +		goto check_newline;
> +	}
> +	pr_err("Unable to locate prefix for emulated Initiator Port:"
> +			" %s\n", i_port);
> +	return -EINVAL;
> +	/*
> +	 * Clear any trailing newline for the NAA WWN
> +	 */
> +check_newline:
> +	if (i_port[strlen(i_port)-1] == '\n')
> +		i_port[strlen(i_port)-1] = '\0';
> +
> +	ret = tcm_vhost_make_nexus(tv_tpg, port_ptr);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +TF_TPG_BASE_ATTR(tcm_vhost, nexus, S_IRUGO | S_IWUSR);
> +
> +static struct configfs_attribute *tcm_vhost_tpg_attrs[] = {
> +	&tcm_vhost_tpg_nexus.attr,
> +	NULL,
> +};
> +
> +static struct se_portal_group *tcm_vhost_make_tpg(
> +	struct se_wwn *wwn,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct tcm_vhost_tport*tport = container_of(wwn,
> +			struct tcm_vhost_tport, tport_wwn);
> +
> +	struct tcm_vhost_tpg *tpg;
> +	unsigned long tpgt;
> +	int ret;
> +
> +	if (strstr(name, "tpgt_") != name)
> +		return ERR_PTR(-EINVAL);
> +	if (strict_strtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
> +		return ERR_PTR(-EINVAL);
> +
> +	tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);
> +	if (!tpg) {
> +		pr_err("Unable to allocate struct tcm_vhost_tpg");
> +		return ERR_PTR(-ENOMEM);
> +	}
> +	mutex_init(&tpg->tv_tpg_mutex);
> +	INIT_LIST_HEAD(&tpg->tv_tpg_list);
> +	tpg->tport = tport;
> +	tpg->tport_tpgt = tpgt;
> +
> +	ret = core_tpg_register(&tcm_vhost_fabric_configfs->tf_ops, wwn,
> +				&tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
> +	if (ret < 0) {
> +		kfree(tpg);
> +		return NULL;
> +	}
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_add_tail(&tpg->tv_tpg_list, &tcm_vhost_list);
> +	mutex_unlock(&tcm_vhost_mutex);
> +
> +	return &tpg->se_tpg;
> +}
> +
> +static void tcm_vhost_drop_tpg(struct se_portal_group *se_tpg)
> +{
> +	struct tcm_vhost_tpg *tpg = container_of(se_tpg,
> +				struct tcm_vhost_tpg, se_tpg);
> +
> +	mutex_lock(&tcm_vhost_mutex);
> +	list_del(&tpg->tv_tpg_list);
> +	mutex_unlock(&tcm_vhost_mutex);
> +	/*
> +	 * Release the virtual I_T Nexus for this vHost TPG
> +	 */
> +	tcm_vhost_drop_nexus(tpg);
> +	/*
> +	 * Deregister the se_tpg from TCM..
> +	 */
> +	core_tpg_deregister(se_tpg);
> +	kfree(tpg);
> +}
> +
> +static struct se_wwn *tcm_vhost_make_tport(
> +	struct target_fabric_configfs *tf,
> +	struct config_group *group,
> +	const char *name)
> +{
> +	struct tcm_vhost_tport *tport;
> +	char *ptr;
> +	u64 wwpn = 0;
> +	int off = 0;
> +
> +	/* if (tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
> +		return ERR_PTR(-EINVAL); */
> +
> +	tport = kzalloc(sizeof(struct tcm_vhost_tport), GFP_KERNEL);
> +	if (!tport) {
> +		pr_err("Unable to allocate struct tcm_vhost_tport");
> +		return ERR_PTR(-ENOMEM);
> +	}

Here also avoid kzalloc pls.

> +	tport->tport_wwpn = wwpn;
> +	/* tcm_vhost_format_wwn(&tport->tport_name[0], TCM_VHOST__NAMELEN, wwpn); */
> +	/*
> +	 * Determine the emulated Protocol Identifier and Target Port Name
> +	 * based on the incoming configfs directory name.
> +	 */
> +	ptr = strstr(name, "naa.");
> +	if (ptr) {
> +		tport->tport_proto_id = SCSI_PROTOCOL_SAS;
> +		goto check_len;
> +	}
> +	ptr = strstr(name, "fc.");
> +	if (ptr) {
> +		tport->tport_proto_id = SCSI_PROTOCOL_FCP;
> +		off = 3; /* Skip over "fc." */
> +		goto check_len;
> +	}
> +	ptr = strstr(name, "iqn.");
> +	if (ptr) {
> +		tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
> +		goto check_len;
> +	}
> +
> +	pr_err("Unable to locate prefix for emulated Target Port:"
> +			" %s\n", name);
> +	kfree(tport);
> +	return ERR_PTR(-EINVAL);
> +
> +check_len:
> +	if (strlen(name) >= TCM_VHOST_NAMELEN) {
> +		pr_err("Emulated %s Address: %s, exceeds"
> +			" max: %d\n", name, tcm_vhost_dump_proto_id(tport),
> +			TCM_VHOST_NAMELEN);
> +		kfree(tport);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	snprintf(&tport->tport_name[0], TCM_VHOST_NAMELEN, "%s", &name[off]);
> +
> +	pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
> +		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport), name);
> +
> +	return &tport->tport_wwn;
> +}
> +
> +static void tcm_vhost_drop_tport(struct se_wwn *wwn)
> +{
> +	struct tcm_vhost_tport *tport = container_of(wwn,
> +				struct tcm_vhost_tport, tport_wwn);
> +
> +	pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
> +		" %s Address: %s\n", tcm_vhost_dump_proto_id(tport),
> +		tport->tport_name);;
> +
> +	kfree(tport);
> +}
> +
> +static ssize_t tcm_vhost_wwn_show_attr_version(
> +	struct target_fabric_configfs *tf,
> +	char *page)
> +{
> +	return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
> +		"on "UTS_RELEASE"\n", TCM_VHOST_VERSION, utsname()->sysname,
> +		utsname()->machine);
> +}
> +
> +TF_WWN_ATTR_RO(tcm_vhost, version);
> +
> +static struct configfs_attribute *tcm_vhost_wwn_attrs[] = {
> +	&tcm_vhost_wwn_version.attr,
> +	NULL,
> +};
> +
> +static struct target_core_fabric_ops tcm_vhost_ops = {
> +	.get_fabric_name		= tcm_vhost_get_fabric_name,
> +	.get_fabric_proto_ident		= tcm_vhost_get_fabric_proto_ident,
> +	.tpg_get_wwn			= tcm_vhost_get_fabric_wwn,
> +	.tpg_get_tag			= tcm_vhost_get_tag,
> +	.tpg_get_default_depth		= tcm_vhost_get_default_depth,
> +	.tpg_get_pr_transport_id	= tcm_vhost_get_pr_transport_id,
> +	.tpg_get_pr_transport_id_len	= tcm_vhost_get_pr_transport_id_len,
> +	.tpg_parse_pr_out_transport_id	= tcm_vhost_parse_pr_out_transport_id,
> +	.tpg_check_demo_mode		= tcm_vhost_check_true,
> +	.tpg_check_demo_mode_cache	= tcm_vhost_check_true,
> +	.tpg_check_demo_mode_write_protect = tcm_vhost_check_false,
> +	.tpg_check_prod_mode_write_protect = tcm_vhost_check_false,
> +	.tpg_alloc_fabric_acl		= tcm_vhost_alloc_fabric_acl,
> +	.tpg_release_fabric_acl		= tcm_vhost_release_fabric_acl,
> +	.tpg_get_inst_index		= tcm_vhost_tpg_get_inst_index,
> +	.release_cmd			= tcm_vhost_release_cmd,
> +	.shutdown_session		= tcm_vhost_shutdown_session,
> +	.close_session			= tcm_vhost_close_session,
> +	.sess_get_index			= tcm_vhost_sess_get_index,
> +	.sess_get_initiator_sid		= NULL,
> +	.write_pending			= tcm_vhost_write_pending,
> +	.write_pending_status		= tcm_vhost_write_pending_status,
> +	.set_default_node_attributes	= tcm_vhost_set_default_node_attrs,
> +	.get_task_tag			= tcm_vhost_get_task_tag,
> +	.get_cmd_state			= tcm_vhost_get_cmd_state,
> +	.queue_data_in			= tcm_vhost_queue_data_in,
> +	.queue_status			= tcm_vhost_queue_status,
> +	.queue_tm_rsp			= tcm_vhost_queue_tm_rsp,
> +	.get_fabric_sense_len		= tcm_vhost_get_fabric_sense_len,
> +	.set_fabric_sense_len		= tcm_vhost_set_fabric_sense_len,
> +	/*
> +	 * Setup function pointers for generic logic in target_core_fabric_configfs.c
> +	 */
> +	.fabric_make_wwn		= tcm_vhost_make_tport,
> +	.fabric_drop_wwn		= tcm_vhost_drop_tport,
> +	.fabric_make_tpg		= tcm_vhost_make_tpg,
> +	.fabric_drop_tpg		= tcm_vhost_drop_tpg,
> +	.fabric_post_link		= tcm_vhost_port_link,
> +	.fabric_pre_unlink		= tcm_vhost_port_unlink,
> +	.fabric_make_np			= NULL,
> +	.fabric_drop_np			= NULL,
> +	.fabric_make_nodeacl		= tcm_vhost_make_nodeacl,
> +	.fabric_drop_nodeacl		= tcm_vhost_drop_nodeacl,
> +};
> +
> +static int tcm_vhost_register_configfs(void)
> +{
> +	struct target_fabric_configfs *fabric;
> +	int ret;
> +
> +	pr_debug("TCM_VHOST fabric module %s on %s/%s"
> +		" on "UTS_RELEASE"\n",TCM_VHOST_VERSION, utsname()->sysname,
> +		utsname()->machine);
> +	/*
> +	 * Register the top level struct config_item_type with TCM core
> +	 */
> +	fabric = target_fabric_configfs_init(THIS_MODULE, "vhost");
> +	if (IS_ERR(fabric)) {
> +		pr_err("target_fabric_configfs_init() failed\n");
> +		return PTR_ERR(fabric);
> +	}
> +	/*
> +	 * Setup fabric->tf_ops from our local tcm_vhost_ops
> +	 */
> +	fabric->tf_ops = tcm_vhost_ops;
> +	/*
> +	 * Setup default attribute lists for various fabric->tf_cit_tmpl
> +	 */
> +	TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
> +	TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
> +	/*
> +	 * Register the fabric for use within TCM
> +	 */
> +	ret = target_fabric_configfs_register(fabric);
> +	if (ret < 0) {
> +		pr_err("target_fabric_configfs_register() failed"
> +				" for TCM_VHOST\n");
> +		return ret;
> +	}
> +	/*
> +	 * Setup our local pointer to *fabric
> +	 */
> +	tcm_vhost_fabric_configfs = fabric;
> +	pr_debug("TCM_VHOST[0] - Set fabric -> tcm_vhost_fabric_configfs\n");
> +	return 0;
> +};
> +
> +static void tcm_vhost_deregister_configfs(void)
> +{
> +	if (!tcm_vhost_fabric_configfs)
> +		return;
> +
> +	target_fabric_configfs_deregister(tcm_vhost_fabric_configfs);
> +	tcm_vhost_fabric_configfs = NULL;
> +	pr_debug("TCM_VHOST[0] - Cleared tcm_vhost_fabric_configfs\n");
> +};
> +
> +static int __init tcm_vhost_init(void)
> +{
> +	int ret = -ENOMEM;
> +
> +	tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0);
> +	if (!tcm_vhost_workqueue)
> +		goto out;
> +
> +	ret = vhost_scsi_register();
> +	if (ret < 0)
> +		goto out_destroy_workqueue;
> +
> +	ret = tcm_vhost_register_configfs();
> +	if (ret < 0)
> +		goto out_vhost_scsi_deregister;
> +
> +	return 0;
> +
> +out_vhost_scsi_deregister:
> +	vhost_scsi_deregister();
> +out_destroy_workqueue:
> +	destroy_workqueue(tcm_vhost_workqueue);
> +out:
> +	return ret;
> +};
> +
> +static void tcm_vhost_exit(void)
> +{
> +	tcm_vhost_deregister_configfs();
> +	vhost_scsi_deregister();
> +	destroy_workqueue(tcm_vhost_workqueue);
> +};
> +
> +MODULE_DESCRIPTION("TCM_VHOST series fabric driver");
> +MODULE_LICENSE("GPL");
> +module_init(tcm_vhost_init);
> +module_exit(tcm_vhost_exit);
> diff --git a/drivers/vhost/tcm/tcm_vhost.h b/drivers/vhost/tcm/tcm_vhost.h
> new file mode 100644
> index 0000000..9d6cace
> --- /dev/null
> +++ b/drivers/vhost/tcm/tcm_vhost.h

I think it's better to just move these defines to tcm_vhost.c

> @@ -0,0 +1,74 @@
> +#define TCM_VHOST_VERSION  "v0.1"
> +#define TCM_VHOST_NAMELEN 256
> +#define TCM_VHOST_MAX_CDB_SIZE 32
> +
> +struct tcm_vhost_cmd {
> +	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
> +	int tvc_vq_desc;
> +	/* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
> +	u64 tvc_tag;
> +	/* The number of scatterlists associated with this cmd */
> +	u32 tvc_sgl_count;
> +	/* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
> +	u32 tvc_lun;
> +	/* Pointer to the SGL formatted memory from virtio-scsi */
> +	struct scatterlist *tvc_sgl;
> +	/* Pointer to response */
> +	struct virtio_scsi_cmd_resp __user *tvc_resp;
> +	/* Pointer to vhost_scsi for our device */
> +	struct vhost_scsi *tvc_vhost;
> +	/* The TCM I/O descriptor that is accessed via container_of() */
> +	struct se_cmd tvc_se_cmd;
> +	/* work item used for cmwq dispatch to tcm_vhost_submission_work() */
> +	struct work_struct work;
> +	/* Copy of the incoming SCSI command descriptor block (CDB) */
> +	unsigned char tvc_cdb[TCM_VHOST_MAX_CDB_SIZE];
> +	/* Sense buffer that will be mapped into outgoing status */
> +	unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
> +	/* Completed commands list, serviced from vhost worker thread */
> +	struct list_head tvc_completion_list;
> +};
> +
> +struct tcm_vhost_nexus {
> +	/* Pointer to TCM session for I_T Nexus */
> +	struct se_session *tvn_se_sess;
> +};
> +
> +struct tcm_vhost_nacl {
> +	/* Binary World Wide unique Port Name for Vhost Initiator port */
> +	u64 iport_wwpn;
> +	/* ASCII formatted WWPN for Sas Initiator port */
> +	char iport_name[TCM_VHOST_NAMELEN];
> +	/* Returned by tcm_vhost_make_nodeacl() */
> +	struct se_node_acl se_node_acl;
> +};
> +
> +struct tcm_vhost_tpg {
> +	/* Vhost port target portal group tag for TCM */
> +	u16 tport_tpgt;
> +	/* Used to track number of TPG Port/Lun Links wrt to explict I_T Nexus shutdown */
> +	atomic_t tv_tpg_port_count;
> +	/* Used for vhost_scsi device reference to tpg_nexus */
> +	atomic_t tv_tpg_vhost_count;
> +	/* list for tcm_vhost_list */
> +	struct list_head tv_tpg_list;
> +	/* Used to protect access for tpg_nexus */
> +	struct mutex tv_tpg_mutex;
> +	/* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
> +	struct tcm_vhost_nexus *tpg_nexus;
> +	/* Pointer back to tcm_vhost_tport */
> +	struct tcm_vhost_tport *tport;
> +	/* Returned by tcm_vhost_make_tpg() */
> +	struct se_portal_group se_tpg;
> +};
> +
> +struct tcm_vhost_tport {
> +	/* SCSI protocol the tport is providing */
> +	u8 tport_proto_id;
> +	/* Binary World Wide unique Port Name for Vhost Target port */
> +	u64 tport_wwpn;
> +	/* ASCII formatted WWPN for Vhost Target port */
> +	char tport_name[TCM_VHOST_NAMELEN];
> +	/* Returned by tcm_vhost_make_tport() */
> +	struct se_wwn tport_wwn;
> +};
> -- 
> 1.7.2.5

Re: [RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Nicholas A. Bellinger]

On Wed, 2012-07-18 at 19:09 +0300, Michael S. Tsirkin wrote:
> On Wed, Jul 18, 2012 at 12:59:32AM +0000, Nicholas A. Bellinger wrote:

<SNIP>

> > 
> > Changelog v2 -> v3:
> > 
> >   Unlock on error in tcm_vhost_drop_nexus() (DanC)
> >   Fix strlen() doesn't count the terminator (DanC)
> >   Call kfree() on an error path (DanC)
> >   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
> >   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
> >   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
> >   as requested by MST (nab)
> > 
> > ---
> >  drivers/staging/Kconfig       |    2 +
> >  drivers/vhost/Makefile        |    2 +
> >  drivers/vhost/tcm/Kconfig     |    6 +
> >  drivers/vhost/tcm/Makefile    |    1 +
> >  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
> >  drivers/vhost/tcm/tcm_vhost.h |   74 ++
> >  6 files changed, 1696 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/vhost/tcm/Kconfig
> >  create mode 100644 drivers/vhost/tcm/Makefile
> >  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
> >  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> > 
> 
> Really sorry about making you run around like that,
> I did not mean moving all of tcm to a directory,
> just adding tcm/Kconfig or adding drivers/vhost/Kconfig.tcm
> because eventually it's easier to keep it all together
> in one place.
> 

Er, apologies for the slight mis-understanding here..  Moving back now +
fixing up the Kbuild bits.

Re: [RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 02:20:58PM -0700, Nicholas A. Bellinger wrote:
> On Wed, 2012-07-18 at 19:09 +0300, Michael S. Tsirkin wrote:
> > On Wed, Jul 18, 2012 at 12:59:32AM +0000, Nicholas A. Bellinger wrote:
> 
> <SNIP>
> 
> > > 
> > > Changelog v2 -> v3:
> > > 
> > >   Unlock on error in tcm_vhost_drop_nexus() (DanC)
> > >   Fix strlen() doesn't count the terminator (DanC)
> > >   Call kfree() on an error path (DanC)
> > >   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
> > >   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
> > >   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
> > >   as requested by MST (nab)
> > > 
> > > ---
> > >  drivers/staging/Kconfig       |    2 +
> > >  drivers/vhost/Makefile        |    2 +
> > >  drivers/vhost/tcm/Kconfig     |    6 +
> > >  drivers/vhost/tcm/Makefile    |    1 +
> > >  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
> > >  drivers/vhost/tcm/tcm_vhost.h |   74 ++
> > >  6 files changed, 1696 insertions(+), 0 deletions(-)
> > >  create mode 100644 drivers/vhost/tcm/Kconfig
> > >  create mode 100644 drivers/vhost/tcm/Makefile
> > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
> > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> > > 
> > 
> > Really sorry about making you run around like that,
> > I did not mean moving all of tcm to a directory,
> > just adding tcm/Kconfig or adding drivers/vhost/Kconfig.tcm
> > because eventually it's easier to keep it all together
> > in one place.
> > 
> 
> Er, apologies for the slight mis-understanding here..  Moving back now +
> fixing up the Kbuild bits.

I'm going offline in several hours and am on vacation for a week
starting tomorrow. So to make 3.6, and if you intend to merge through my
tree, the best bet is if you can send the final version real soon now.

-- 
MST

Re: [RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Nicholas A. Bellinger]

On Fri, 2012-07-20 at 15:03 +0300, Michael S. Tsirkin wrote:
> On Wed, Jul 18, 2012 at 02:20:58PM -0700, Nicholas A. Bellinger wrote:
> > On Wed, 2012-07-18 at 19:09 +0300, Michael S. Tsirkin wrote:
> > > On Wed, Jul 18, 2012 at 12:59:32AM +0000, Nicholas A. Bellinger wrote:
> > 
> > <SNIP>
> > 
> > > > 
> > > > Changelog v2 -> v3:
> > > > 
> > > >   Unlock on error in tcm_vhost_drop_nexus() (DanC)
> > > >   Fix strlen() doesn't count the terminator (DanC)
> > > >   Call kfree() on an error path (DanC)
> > > >   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
> > > >   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
> > > >   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
> > > >   as requested by MST (nab)
> > > > 
> > > > ---
> > > >  drivers/staging/Kconfig       |    2 +
> > > >  drivers/vhost/Makefile        |    2 +
> > > >  drivers/vhost/tcm/Kconfig     |    6 +
> > > >  drivers/vhost/tcm/Makefile    |    1 +
> > > >  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
> > > >  drivers/vhost/tcm/tcm_vhost.h |   74 ++
> > > >  6 files changed, 1696 insertions(+), 0 deletions(-)
> > > >  create mode 100644 drivers/vhost/tcm/Kconfig
> > > >  create mode 100644 drivers/vhost/tcm/Makefile
> > > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
> > > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> > > > 
> > > 
> > > Really sorry about making you run around like that,
> > > I did not mean moving all of tcm to a directory,
> > > just adding tcm/Kconfig or adding drivers/vhost/Kconfig.tcm
> > > because eventually it's easier to keep it all together
> > > in one place.
> > > 
> > 
> > Er, apologies for the slight mis-understanding here..  Moving back now +
> > fixing up the Kbuild bits.
> 
> I'm going offline in several hours and am on vacation for a week
> starting tomorrow. So to make 3.6, and if you intend to merge through my
> tree, the best bet is if you can send the final version real soon now.
> 

Ok, thanks for the heads up here..

So aside from Greg-KH's feedback to avoid the drivers/staging/ Kconfig
include usage, and one more bugfix from DanC from this morning those are
the only pending changes for RFC-v4.

If it's OK I'd prefer to take these via target-pending with the
necessary Acked-By's, especially if you'll be AFK next week..

Would you like to see a RFC-v4 with these changes included..?

Thank you,

--nab

Re: [RFC-v3 4/4] tcm_vhost: Initial merge for vhost level target fabric driver

[Nicholas A. Bellinger]

On Fri, 2012-07-20 at 11:00 -0700, Nicholas A. Bellinger wrote:
> On Fri, 2012-07-20 at 15:03 +0300, Michael S. Tsirkin wrote:
> > On Wed, Jul 18, 2012 at 02:20:58PM -0700, Nicholas A. Bellinger wrote:
> > > On Wed, 2012-07-18 at 19:09 +0300, Michael S. Tsirkin wrote:
> > > > On Wed, Jul 18, 2012 at 12:59:32AM +0000, Nicholas A. Bellinger wrote:
> > > 
> > > <SNIP>
> > > 
> > > > > 
> > > > > Changelog v2 -> v3:
> > > > > 
> > > > >   Unlock on error in tcm_vhost_drop_nexus() (DanC)
> > > > >   Fix strlen() doesn't count the terminator (DanC)
> > > > >   Call kfree() on an error path (DanC)
> > > > >   Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
> > > > >   Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
> > > > >   Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
> > > > >   as requested by MST (nab)
> > > > > 
> > > > > ---
> > > > >  drivers/staging/Kconfig       |    2 +
> > > > >  drivers/vhost/Makefile        |    2 +
> > > > >  drivers/vhost/tcm/Kconfig     |    6 +
> > > > >  drivers/vhost/tcm/Makefile    |    1 +
> > > > >  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
> > > > >  drivers/vhost/tcm/tcm_vhost.h |   74 ++
> > > > >  6 files changed, 1696 insertions(+), 0 deletions(-)
> > > > >  create mode 100644 drivers/vhost/tcm/Kconfig
> > > > >  create mode 100644 drivers/vhost/tcm/Makefile
> > > > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
> > > > >  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> > > > > 
> > > > 
> > > > Really sorry about making you run around like that,
> > > > I did not mean moving all of tcm to a directory,
> > > > just adding tcm/Kconfig or adding drivers/vhost/Kconfig.tcm
> > > > because eventually it's easier to keep it all together
> > > > in one place.
> > > > 
> > > 
> > > Er, apologies for the slight mis-understanding here..  Moving back now +
> > > fixing up the Kbuild bits.
> > 
> > I'm going offline in several hours and am on vacation for a week
> > starting tomorrow. So to make 3.6, and if you intend to merge through my
> > tree, the best bet is if you can send the final version real soon now.
> > 
> 
> Ok, thanks for the heads up here..
> 
> So aside from Greg-KH's feedback to avoid the drivers/staging/ Kconfig
> include usage, and one more bugfix from DanC from this morning those are
> the only pending changes for RFC-v4.
> 
> If it's OK I'd prefer to take these via target-pending with the
> necessary Acked-By's, especially if you'll be AFK next week..
> 
> Would you like to see a RFC-v4 with these changes included..?
> 
> Thank you,
> 

Actually sorry, the patch from DanC is for target core, and not
tcm_vhost specific change..

So really the only thing left to resolve for an initial merge is
Greg-KH's comments wrt to drivers/staging Kconfig usage..

Are you OK with just adding CONFIG_STAGING following Greg-KH's
feedback..?

Re: [RFC-v3 0/4] tcm_vhost+cmwq fabric driver code for-3.6

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 12:59:28AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Hi folks,
> 
> The following is the RFC-v3 series of tcm_vhost target fabric driver code
> currently in-flight for-3.6 mainline code.
> 
> With the merge window opening soon, the tcm_vhost code has started seeing
> time in linux-next.  The v2 -> v3 changelog from the last week is currently
> looking like:
> 
>  *) Unlock on error in tcm_vhost_drop_nexus() (DanC)
>  *) Fix strlen() doesn't count the terminator (DanC)
>  *) Call kfree() on an error path (DanC)
>  *) Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
>  *) Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
>  *) Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
>     as requested by MST (nab)

I actually only wanted to have a separate Kconfig (in a separate
directory or Kconfig.tcm), so you do not need to move code back to move
driver out of staging.  But if you prefer this, I'm fine with it too for
now.

> Thanks to Dan Carpenter for his smatch fixes this past round.
> 
> Also as requested by MST, the code has been moved to a seperate tcm/ subdirectory
> under drivers/vhost/ so that it can be included under staging's config options
> until we can settle on the necessary userspace bits for QEMU and kvm-tool.
> 
> The updated series will be going out shortly to target-pending/for-next-merge.
> 
> Please have another look and let us know if you have any concerned.
> 
> Thanks!
> 
> Nicholas Bellinger (2):
>   vhost: Add vhost_scsi specific defines
>   tcm_vhost: Initial merge for vhost level target fabric driver
> 
> Stefan Hajnoczi (2):
>   vhost: Separate vhost-net features from vhost features
>   vhost: make vhost work queue visible
> 
>  drivers/staging/Kconfig       |    2 +
>  drivers/vhost/Makefile        |    2 +
>  drivers/vhost/net.c           |    4 +-
>  drivers/vhost/tcm/Kconfig     |    6 +
>  drivers/vhost/tcm/Makefile    |    1 +
>  drivers/vhost/tcm/tcm_vhost.c | 1611 +++++++++++++++++++++++++++++++++++++++++
>  drivers/vhost/tcm/tcm_vhost.h |   74 ++
>  drivers/vhost/test.c          |    4 +-
>  drivers/vhost/vhost.c         |    5 +-
>  drivers/vhost/vhost.h         |    6 +-
>  include/linux/vhost.h         |    9 +
>  11 files changed, 1716 insertions(+), 8 deletions(-)
>  create mode 100644 drivers/vhost/tcm/Kconfig
>  create mode 100644 drivers/vhost/tcm/Makefile
>  create mode 100644 drivers/vhost/tcm/tcm_vhost.c
>  create mode 100644 drivers/vhost/tcm/tcm_vhost.h
> 
> -- 
> 1.7.2.5

Re: [RFC-v3 0/4] tcm_vhost+cmwq fabric driver code for-3.6

[Michael S. Tsirkin]

On Wed, Jul 18, 2012 at 12:59:28AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Hi folks,
> 
> The following is the RFC-v3 series of tcm_vhost target fabric driver code
> currently in-flight for-3.6 mainline code.

So I sent some comments. I think it's in an OK state for a staging
driver.  I'd suggest doing some interations while there is still time
and the rest we can fix up in tree.

-- 
MST