Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-05-08 Thread Hannes Reinecke 

On 05/01/2014 04:51 PM, Christoph Hellwig wrote:

Instead of letting the ULD play games with the prep_fn move back to
the model of a central prep_fn with a callback to the ULD.  This
already cleans up and shortens the code by itself, and will be required
to properly support blk-mq in the SCSI midlayer.



... And leaving the device handler to still provide a prep_fn().
But that's for another day.


Signed-off-by: Christoph Hellwig h...@lst.de
Reviewed-by: Nicholas Bellinger n...@linux-iscsi.org
Reviewed-by: Mike Christie micha...@cs.wisc.edu


Reviewed-by: Hannes Reinecke h...@suse.de

Cheers,

Hannes
--
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h...@suse.de  +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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[PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-05-01 Thread Christoph Hellwig 
Instead of letting the ULD play games with the prep_fn move back to
the model of a central prep_fn with a callback to the ULD.  This
already cleans up and shortens the code by itself, and will be required
to properly support blk-mq in the SCSI midlayer.

Signed-off-by: Christoph Hellwig h...@lst.de
Reviewed-by: Nicholas Bellinger n...@linux-iscsi.org
Reviewed-by: Mike Christie micha...@cs.wisc.edu
---
 drivers/scsi/scsi_lib.c|   66 ++--
 drivers/scsi/sd.c  |   44 ++---
 drivers/scsi/sr.c  |   19 -
 include/scsi/scsi_driver.h |9 ++
 4 files changed, 62 insertions(+), 76 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 045822b..9f841df 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1073,15 +1073,7 @@ static struct scsi_cmnd *scsi_get_cmd_from_req(struct 
scsi_device *sdev,
 
 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 {
-   struct scsi_cmnd *cmd;
-   int ret = scsi_prep_state_check(sdev, req);
-
-   if (ret != BLKPREP_OK)
-   return ret;
-
-   cmd = scsi_get_cmd_from_req(sdev, req);
-   if (unlikely(!cmd))
-   return BLKPREP_DEFER;
+   struct scsi_cmnd *cmd = req-special;
 
/*
 * BLOCK_PC requests may transfer data, in which case they must
@@ -1125,15 +1117,11 @@ EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
  */
 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
 {
-   struct scsi_cmnd *cmd;
-   int ret = scsi_prep_state_check(sdev, req);
-
-   if (ret != BLKPREP_OK)
-   return ret;
+   struct scsi_cmnd *cmd = req-special;
 
if (unlikely(sdev-scsi_dh_data  sdev-scsi_dh_data-scsi_dh
  sdev-scsi_dh_data-scsi_dh-prep_fn)) {
-   ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
+   int ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
if (ret != BLKPREP_OK)
return ret;
}
@@ -1143,16 +1131,13 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct 
request *req)
 */
BUG_ON(!req-nr_phys_segments);
 
-   cmd = scsi_get_cmd_from_req(sdev, req);
-   if (unlikely(!cmd))
-   return BLKPREP_DEFER;
-
memset(cmd-cmnd, 0, BLK_MAX_CDB);
return scsi_init_io(cmd, GFP_ATOMIC);
 }
 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
 
-int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
+static int
+scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 {
int ret = BLKPREP_OK;
 
@@ -1204,9 +1189,9 @@ int scsi_prep_state_check(struct scsi_device *sdev, 
struct request *req)
}
return ret;
 }
-EXPORT_SYMBOL(scsi_prep_state_check);
 
-int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
+static int
+scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 {
struct scsi_device *sdev = q-queuedata;
 
@@ -1237,18 +1222,44 @@ int scsi_prep_return(struct request_queue *q, struct 
request *req, int ret)
 
return ret;
 }
-EXPORT_SYMBOL(scsi_prep_return);
 
-int scsi_prep_fn(struct request_queue *q, struct request *req)
+static int scsi_prep_fn(struct request_queue *q, struct request *req)
 {
struct scsi_device *sdev = q-queuedata;
-   int ret = BLKPREP_KILL;
+   struct scsi_cmnd *cmd;
+   int ret;
 
-   if (req-cmd_type == REQ_TYPE_BLOCK_PC)
+   ret = scsi_prep_state_check(sdev, req);
+   if (ret != BLKPREP_OK)
+   goto out;
+
+   cmd = scsi_get_cmd_from_req(sdev, req);
+   if (unlikely(!cmd)) {
+   ret = BLKPREP_DEFER;
+   goto out;
+   }
+
+   if (req-cmd_type == REQ_TYPE_FS)
+   ret = scsi_cmd_to_driver(cmd)-init_command(cmd);
+   else if (req-cmd_type == REQ_TYPE_BLOCK_PC)
ret = scsi_setup_blk_pc_cmnd(sdev, req);
+   else
+   ret = BLKPREP_KILL;
+
+out:
return scsi_prep_return(q, req, ret);
 }
-EXPORT_SYMBOL(scsi_prep_fn);
+
+static void scsi_unprep_fn(struct request_queue *q, struct request *req)
+{
+   if (req-cmd_type == REQ_TYPE_FS) {
+   struct scsi_cmnd *cmd = req-special;
+   struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
+
+   if (drv-uninit_command)
+   drv-uninit_command(cmd);
+   }
+}
 
 /*
  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
@@ -1669,6 +1680,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device 
*sdev)
return NULL;
 
blk_queue_prep_rq(q, scsi_prep_fn);
+   blk_queue_unprep_rq(q, scsi_unprep_fn);
blk_queue_softirq_done(q, scsi_softirq_done);
blk_queue_rq_timed_out(q, scsi_times_out);
blk_queue_lld_busy(q, scsi_lld_busy);
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c

Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-31 Thread Christoph Hellwig 
On Sun, Mar 30, 2014 at 10:45:04PM -0700, Nicholas A. Bellinger wrote:
   int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
   {
  -   struct scsi_cmnd *cmd;
  -   int ret = scsi_prep_state_check(sdev, req);
  -
  -   if (ret != BLKPREP_OK)
  -   return ret;
  -
  -   cmd = scsi_get_cmd_from_req(sdev, req);
  -   if (unlikely(!cmd))
  -   return BLKPREP_DEFER;
  +   struct scsi_cmnd *cmd = req-special;
   
 
 Mmm, I thought that req-special was only holding a pointer to a
 pre-allocated scsi_cmnd during mq operation, no..?

For the mq case the block layer sets up req-special.  For the old case
scsi_get_cmd_from_req sets up req-special the first it is called, and
leaves it in there until the command is done.

  +   ret = scsi_prep_state_check(sdev, req);
  +   if (ret != BLKPREP_OK)
  +   goto out;
  +
  +   cmd = scsi_get_cmd_from_req(sdev, req);
  +   if (unlikely(!cmd)) {
  +   ret = BLKPREP_DEFER;
  +   goto out;
  +   }
  +


From here the req-special pointer may or may not be set depending on mq
operation, no..?

a) there is no blk-mq support yet in James tree (+ these patches)
b) even in my scsi-mq tree this code path won't be called for the mq case
c) after scsi_get_cmd_from_req returns req-special will always be set up
   to point to the scsi_cmnd:

static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
struct request *req)
{
struct scsi_cmnd *cmd;

if (!req-special) {
...

req-special = cmd;
} else {
cmd = req-special;
}

/* pull a tag out of the request if we have one */
cmd-tag = req-tag;
cmd-request = req;

cmd-cmnd = req-cmd;   
cmd-prot_op = SCSI_PROT_NORMAL;

return cmd;
}

  }
  ret = scsi_setup_fs_cmnd(sdp, rq);
  if (ret != BLKPREP_OK)
 
 And this currently assumes req-special is always set when calling
 scsi_setup_fs_cmnd()

That is the case both before and after this patch.

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Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-31 Thread Nicholas A. Bellinger 
On Mon, 2014-03-31 at 08:08 +0200, Christoph Hellwig wrote:
 On Sun, Mar 30, 2014 at 10:45:04PM -0700, Nicholas A. Bellinger wrote:
int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
{
   - struct scsi_cmnd *cmd;
   - int ret = scsi_prep_state_check(sdev, req);
   -
   - if (ret != BLKPREP_OK)
   - return ret;
   -
   - cmd = scsi_get_cmd_from_req(sdev, req);
   - if (unlikely(!cmd))
   - return BLKPREP_DEFER;
   + struct scsi_cmnd *cmd = req-special;

  
  Mmm, I thought that req-special was only holding a pointer to a
  pre-allocated scsi_cmnd during mq operation, no..?
 
 For the mq case the block layer sets up req-special.  For the old case
 scsi_get_cmd_from_req sets up req-special the first it is called, and
 leaves it in there until the command is done.

Er, yes of course.

Reviewed-by: Nicholas Bellinger n...@linux-iscsi.org

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Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-31 Thread Mike Christie 
On 03/27/2014 11:14 AM, Christoph Hellwig wrote:
 @@ -1663,6 +1652,8 @@ static int sd_done(struct scsi_cmnd *SCpnt)
   unsigned char op = SCpnt-cmnd[0];
   unsigned char unmap = SCpnt-cmnd[1]  8;
  
 + sd_uninit_command(SCpnt);
 +

The above call would free the cmnd-cmnd and set it to null. If then
scsi_io_completion was going to do some error processing it looks like
it could try to access the scsi_cmnd-cmnd field.

With the current code that would not be a problem because the blk unprep
callback is not called until the block layer does its request cleanup in
blk_finish_request which as you know is after
scsi_io_completion/scsi_end_request is done with the cmnd.
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Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-31 Thread Christoph Hellwig 
On Mon, Mar 31, 2014 at 01:56:13AM -0500, Mike Christie wrote:
 The above call would free the cmnd-cmnd and set it to null. If then
 scsi_io_completion was going to do some error processing it looks like
 it could try to access the scsi_cmnd-cmnd field.
 
 With the current code that would not be a problem because the blk unprep
 callback is not called until the block layer does its request cleanup in
 blk_finish_request which as you know is after
 scsi_io_completion/scsi_end_request is done with the cmnd.

Right, we should probabl call -uninit_command at that place as well
instead of calling it internall in -done.
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Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-31 Thread Christoph Hellwig 
 The above call would free the cmnd-cmnd and set it to null. If then
 scsi_io_completion was going to do some error processing it looks like
 it could try to access the scsi_cmnd-cmnd field.
 
 With the current code that would not be a problem because the blk unprep
 callback is not called until the block layer does its request cleanup in
 blk_finish_request which as you know is after
 scsi_io_completion/scsi_end_request is done with the cmnd.

This incremental patches fixes the issue, and makes sure the uninit calls are
nicely paired like the rest of the I/O completion routines after patch 2:


diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 48c5c77..8e79612 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -490,8 +490,6 @@ static void scsi_requeue_command(struct request_queue *q, 
struct scsi_cmnd *cmd)
struct request *req = cmd-request;
unsigned long flags;
 
-   scsi_uninit_command(cmd);
-
spin_lock_irqsave(q-queue_lock, flags);
blk_unprep_request(req);
req-special = NULL;
@@ -941,6 +939,7 @@ requeue:
/* Unprep the request and put it back at the head of the queue.
 * A new command will be prepared and issued.
 */
+   scsi_uninit_command(cmd);
scsi_release_buffers(cmd);
scsi_requeue_command(q, cmd);
break;
@@ -956,6 +955,7 @@ requeue:
return;
 
 next_command:
+   scsi_uninit_command(cmd);
scsi_release_buffers(cmd);
scsi_next_command(cmd);
 }
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d95c4fd..d99cb3f 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1652,8 +1652,6 @@ static int sd_done(struct scsi_cmnd *SCpnt)
unsigned char op = SCpnt-cmnd[0];
unsigned char unmap = SCpnt-cmnd[1]  8;
 
-   sd_uninit_command(SCpnt);
-
if (req-cmd_flags  REQ_DISCARD || req-cmd_flags  REQ_WRITE_SAME) {
if (!result) {
good_bytes = blk_rq_bytes(req);
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Re: [PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-30 Thread Nicholas A. Bellinger 
On Thu, 2014-03-27 at 17:14 +0100, Christoph Hellwig wrote:
 Move control of the prep_fn back from the ULDs into the scsi layer.  Besides
 cleaning up the code and removing the only use of the unprep_fn
 requeuest_queue method this also prepares for usinng blk-mq, which doesn't
 have equivalent functionality to the prep_fn method and requires the driver
 to provide just a single I/O submission method.
 
 Signed-off-by: Christoph Hellwig h...@lst.de
 ---
  drivers/scsi/scsi_lib.c|   66 
 ++--
  drivers/scsi/sd.c  |   46 +++---
  drivers/scsi/sr.c  |   19 -
  include/scsi/scsi_driver.h |8 ++
  4 files changed, 63 insertions(+), 76 deletions(-)
 
 diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
 index a73751b..48c5c77 100644
 --- a/drivers/scsi/scsi_lib.c
 +++ b/drivers/scsi/scsi_lib.c

SNIP

 @@ -1071,15 +1083,7 @@ static struct scsi_cmnd *scsi_get_cmd_from_req(struct 
 scsi_device *sdev,
  
  int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
  {
 - struct scsi_cmnd *cmd;
 - int ret = scsi_prep_state_check(sdev, req);
 -
 - if (ret != BLKPREP_OK)
 - return ret;
 -
 - cmd = scsi_get_cmd_from_req(sdev, req);
 - if (unlikely(!cmd))
 - return BLKPREP_DEFER;
 + struct scsi_cmnd *cmd = req-special;
  

Mmm, I thought that req-special was only holding a pointer to a
pre-allocated scsi_cmnd during mq operation, no..?

   /*
* BLOCK_PC requests may transfer data, in which case they must
 @@ -1123,15 +1127,11 @@ EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
   */
  int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
  {
 - struct scsi_cmnd *cmd;
 - int ret = scsi_prep_state_check(sdev, req);
 -
 - if (ret != BLKPREP_OK)
 - return ret;
 + struct scsi_cmnd *cmd = req-special;
  

Ditto here for REQ_TYPE_FS_CMND

   if (unlikely(sdev-scsi_dh_data  sdev-scsi_dh_data-scsi_dh
 sdev-scsi_dh_data-scsi_dh-prep_fn)) {
 - ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
 + int ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
   if (ret != BLKPREP_OK)
   return ret;
   }
 @@ -1141,16 +1141,13 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, 
 struct request *req)
*/
   BUG_ON(!req-nr_phys_segments);
  
 - cmd = scsi_get_cmd_from_req(sdev, req);
 - if (unlikely(!cmd))
 - return BLKPREP_DEFER;
 -
   memset(cmd-cmnd, 0, BLK_MAX_CDB);
   return scsi_init_io(cmd, GFP_ATOMIC);
  }
  EXPORT_SYMBOL(scsi_setup_fs_cmnd);
  
 -int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 +static int
 +scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
  {
   int ret = BLKPREP_OK;
  
 @@ -1202,9 +1199,9 @@ int scsi_prep_state_check(struct scsi_device *sdev, 
 struct request *req)
   }
   return ret;
  }
 -EXPORT_SYMBOL(scsi_prep_state_check);
  
 -int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 +static int
 +scsi_prep_return(struct request_queue *q, struct request *req, int ret)
  {
   struct scsi_device *sdev = q-queuedata;
  
 @@ -1235,18 +1232,33 @@ int scsi_prep_return(struct request_queue *q, struct 
 request *req, int ret)
  
   return ret;
  }
 -EXPORT_SYMBOL(scsi_prep_return);
  
 -int scsi_prep_fn(struct request_queue *q, struct request *req)
 +static int scsi_prep_fn(struct request_queue *q, struct request *req)
  {
   struct scsi_device *sdev = q-queuedata;
 - int ret = BLKPREP_KILL;
 + struct scsi_cmnd *cmd;
 + int ret;
  
 - if (req-cmd_type == REQ_TYPE_BLOCK_PC)
 + ret = scsi_prep_state_check(sdev, req);
 + if (ret != BLKPREP_OK)
 + goto out;
 +
 + cmd = scsi_get_cmd_from_req(sdev, req);
 + if (unlikely(!cmd)) {
 + ret = BLKPREP_DEFER;
 + goto out;
 + }
 +

From here the req-special pointer may or may not be set depending on mq
operation, no..?

 + if (req-cmd_type == REQ_TYPE_FS)
 + ret = scsi_cmd_to_driver(cmd)-init_command(cmd);
 + else if (req-cmd_type == REQ_TYPE_BLOCK_PC)
   ret = scsi_setup_blk_pc_cmnd(sdev, req);
 + else
 + ret = BLKPREP_KILL;
 +
 +out:
   return scsi_prep_return(q, req, ret);
  }
 -EXPORT_SYMBOL(scsi_prep_fn);
  
  /*
   * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
 diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
 index 89e6c04..d95c4fd 100644
 --- a/drivers/scsi/sd.c
 +++ b/drivers/scsi/sd.c

SNIP

 @@ -886,12 +882,6 @@ static int sd_prep_fn(struct request_queue *q, struct 
 request *rq)
   } else if (rq-cmd_flags  REQ_FLUSH) {
   ret = scsi_setup_flush_cmnd(sdp, rq);
   goto out;
 - } else if (rq-cmd_type == REQ_TYPE_BLOCK_PC) {
 - ret =

[PATCH 3/4] scsi: reintroduce scsi_driver.init_command

2014-03-27 Thread Christoph Hellwig 
Move control of the prep_fn back from the ULDs into the scsi layer.  Besides
cleaning up the code and removing the only use of the unprep_fn
requeuest_queue method this also prepares for usinng blk-mq, which doesn't
have equivalent functionality to the prep_fn method and requires the driver
to provide just a single I/O submission method.

Signed-off-by: Christoph Hellwig h...@lst.de
---
 drivers/scsi/scsi_lib.c|   66 ++--
 drivers/scsi/sd.c  |   46 +++---
 drivers/scsi/sr.c  |   19 -
 include/scsi/scsi_driver.h |8 ++
 4 files changed, 63 insertions(+), 76 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a73751b..48c5c77 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -456,6 +456,16 @@ void scsi_requeue_run_queue(struct work_struct *work)
scsi_run_queue(q);
 }
 
+static void scsi_uninit_command(struct scsi_cmnd *cmd)
+{
+   if (cmd-request-cmd_type == REQ_TYPE_FS) {
+   struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
+
+   if (drv-uninit_command)
+   drv-uninit_command(cmd);
+   }
+}
+
 /*
  * Function:   scsi_requeue_command()
  *
@@ -480,6 +490,8 @@ static void scsi_requeue_command(struct request_queue *q, 
struct scsi_cmnd *cmd)
struct request *req = cmd-request;
unsigned long flags;
 
+   scsi_uninit_command(cmd);
+
spin_lock_irqsave(q-queue_lock, flags);
blk_unprep_request(req);
req-special = NULL;
@@ -1071,15 +1083,7 @@ static struct scsi_cmnd *scsi_get_cmd_from_req(struct 
scsi_device *sdev,
 
 int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 {
-   struct scsi_cmnd *cmd;
-   int ret = scsi_prep_state_check(sdev, req);
-
-   if (ret != BLKPREP_OK)
-   return ret;
-
-   cmd = scsi_get_cmd_from_req(sdev, req);
-   if (unlikely(!cmd))
-   return BLKPREP_DEFER;
+   struct scsi_cmnd *cmd = req-special;
 
/*
 * BLOCK_PC requests may transfer data, in which case they must
@@ -1123,15 +1127,11 @@ EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
  */
 int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
 {
-   struct scsi_cmnd *cmd;
-   int ret = scsi_prep_state_check(sdev, req);
-
-   if (ret != BLKPREP_OK)
-   return ret;
+   struct scsi_cmnd *cmd = req-special;
 
if (unlikely(sdev-scsi_dh_data  sdev-scsi_dh_data-scsi_dh
  sdev-scsi_dh_data-scsi_dh-prep_fn)) {
-   ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
+   int ret = sdev-scsi_dh_data-scsi_dh-prep_fn(sdev, req);
if (ret != BLKPREP_OK)
return ret;
}
@@ -1141,16 +1141,13 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct 
request *req)
 */
BUG_ON(!req-nr_phys_segments);
 
-   cmd = scsi_get_cmd_from_req(sdev, req);
-   if (unlikely(!cmd))
-   return BLKPREP_DEFER;
-
memset(cmd-cmnd, 0, BLK_MAX_CDB);
return scsi_init_io(cmd, GFP_ATOMIC);
 }
 EXPORT_SYMBOL(scsi_setup_fs_cmnd);
 
-int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
+static int
+scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 {
int ret = BLKPREP_OK;
 
@@ -1202,9 +1199,9 @@ int scsi_prep_state_check(struct scsi_device *sdev, 
struct request *req)
}
return ret;
 }
-EXPORT_SYMBOL(scsi_prep_state_check);
 
-int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
+static int
+scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 {
struct scsi_device *sdev = q-queuedata;
 
@@ -1235,18 +1232,33 @@ int scsi_prep_return(struct request_queue *q, struct 
request *req, int ret)
 
return ret;
 }
-EXPORT_SYMBOL(scsi_prep_return);
 
-int scsi_prep_fn(struct request_queue *q, struct request *req)
+static int scsi_prep_fn(struct request_queue *q, struct request *req)
 {
struct scsi_device *sdev = q-queuedata;
-   int ret = BLKPREP_KILL;
+   struct scsi_cmnd *cmd;
+   int ret;
 
-   if (req-cmd_type == REQ_TYPE_BLOCK_PC)
+   ret = scsi_prep_state_check(sdev, req);
+   if (ret != BLKPREP_OK)
+   goto out;
+
+   cmd = scsi_get_cmd_from_req(sdev, req);
+   if (unlikely(!cmd)) {
+   ret = BLKPREP_DEFER;
+   goto out;
+   }
+
+   if (req-cmd_type == REQ_TYPE_FS)
+   ret = scsi_cmd_to_driver(cmd)-init_command(cmd);
+   else if (req-cmd_type == REQ_TYPE_BLOCK_PC)
ret = scsi_setup_blk_pc_cmnd(sdev, req);
+   else
+   ret = BLKPREP_KILL;
+
+out:
return scsi_prep_return(q, req, ret);
 }
-EXPORT_SYMBOL(scsi_prep_fn);
 
 /*
  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
diff --git