Re: [PATCH 2/3] [tgt]: Add bs_sg struct device_type_templatesg_template and struct backingstore_template->bs_init()

[FUJITA Tomonori]

On Sun,  6 Jun 2010 20:50:32 -0700
"Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx> wrote:

> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> 
> This patch adds struct device_type_template sg_template to usr/bs_sg.c used for STGT LUN
> passthrough with the new bs_sg_lu_init() and bs_sg_rw() functions following usr/sbc.c code
> for TYPE_DISK, but should work for any device type.
> 
> It also adds struct bs_sg_init() that is called from existing usr/target.c:tgt_device_create()
> code via struct backingstore_template->bs_init() in order to setup the passthrough specific
> queue and completion handlers for struct scsi_lu->cmd_perform() and ->cmd_done().
> 
> Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
>  usr/bs_sg.c |   69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 69 insertions(+), 0 deletions(-)
> 
> diff --git a/usr/bs_sg.c b/usr/bs_sg.c
> index 8baa480..23676ef 100644
> --- a/usr/bs_sg.c
> +++ b/usr/bs_sg.c
> @@ -38,9 +38,12 @@
>  #include "util.h"
>  #include "tgtd.h"
>  #include "scsi.h"
> +#include "spc.h"
> +#include "tgtadm_error.h"
>  
>  #define BS_SG_RESVD_SZ  (512 * 1024)
>  #define BS_SG_TIMEOUT	2000
> +#define BS_SG_SHIFT	9
>  
>  static int graceful_read(int fd, void *p_read, int to_read)
>  {
> @@ -82,6 +85,32 @@ static int graceful_write(int fd, void *p_write, int to_write)
>  	return 0;
>  }
>  
> +static int bs_sg_rw(int host_no, struct scsi_cmd *cmd)
> +{
> +	int ret;
> +	unsigned char key = ILLEGAL_REQUEST;
> +	uint16_t asc = ASC_LUN_NOT_SUPPORTED;
> +
> +	cmd->scsi_cmd_done = target_cmd_io_done;
> +
> +	cmd->offset = (scsi_rw_offset(cmd->scb) << BS_SG_SHIFT);

No need for passthough, I think.


> +	ret = cmd->dev->bst->bs_cmd_submit(cmd);
> +	if (ret) {
> +		key = HARDWARE_ERROR;
> +		asc = ASC_INTERNAL_TGT_FAILURE;
> +	} else {
> +		set_cmd_mmapio(cmd);

This is wrong since this code doesn't mmap io. We can just remove
this.


> +		return SAM_STAT_GOOD;
> +	}
> +
> +	cmd->offset = 0;
> +	scsi_set_in_resid_by_actual(cmd, 0);
> +	scsi_set_out_resid_by_actual(cmd, 0);
> +
> +	sense_data_build(cmd, key, asc);
> +	return SAM_STAT_CHECK_CONDITION;
> +}
> +
>  static void set_cmd_failed(struct scsi_cmd *cmd)
>  {
>  	int result = SAM_STAT_CHECK_CONDITION;
> @@ -192,6 +221,25 @@ static int init_sg_device(int fd)
>  	return 0;
>  }
>  
> +static int bs_sg_init(struct scsi_lu *lu)
> +{
> +	/*
> +	 * Setup struct scsi_lu->cmd_perform() passthrough pointer
> +	 * (if available) for the underlying device type.
> +	 */
> +	lu->cmd_perform = &target_cmd_perform_passthrough;
> +	if (!(lu->cmd_perform)) {
> +		eprintf("Unable to locate lu->cmd_perform() for bs_sg\n");
> +		return -1;
> +	}
> +	/*
> +	 * Setup struct scsi_lu->cmd_done() passthrough pointer using
> +	 * usr/target.c:__cmd_done_passthrough().
> +	 */
> +	lu->cmd_done = &__cmd_done_passthrough;
> +	return 0;
> +}
> +
>  static int bs_sg_open(struct scsi_lu *lu, char *path, int *fd, uint64_t *size)
>  {
>  	int sg_fd, err;
> @@ -235,16 +283,37 @@ static int bs_sg_cmd_done(struct scsi_cmd *cmd)
>  	return 0;
>  }
>  
> +static int bs_sg_lu_init(struct scsi_lu *lu)
> +{
> +	if (spc_lu_init(lu))
> +		return TGTADM_NOMEM;
> +
> +	return 0;
> +}
> +
>  static struct backingstore_template sg_bst = {
>  	.bs_name		= "sg",
>  	.bs_datasize		= 0,
> +	.bs_passthrough		= 1,
> +	.bs_init		= bs_sg_init,
>  	.bs_open		= bs_sg_open,
>  	.bs_close		= bs_sg_close,
>  	.bs_cmd_submit		= bs_sg_cmd_submit,
>  	.bs_cmd_done		= bs_sg_cmd_done,
>  };
>  
> +static struct device_type_template sg_template = {
> +	.type			= 0,

Let's create a new type to simplify things (e.g. we can avoid adding
sg_bst->bs_passthrough).
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