Re: [PATCH] [Target_Core_Mod/pSCSI]: Add optional legacy scsi_execute_async()usage for Linux/SCSI passthrough

From: Boaz Harrosh
Date: Sun Apr 19 2009 - 06:57:13 EST

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On 04/17/2009 04:09 AM, Nicholas A. Bellinger wrote:
> Greetings all,
>
> This patch modifies the Target_Core_Mod/ConfigFS v3.0 PSCSI subsystem plugin for target_core_mod v3.0 to add
> a configurable method of choosing legacy scsi_execute_async() usage for underlying SCSI HTCL struct scsi_device.
> This method is still the only method of issuing I/O to the Linux SCSI subsystem is used for non TYPE_DISK hardware
> SCSI and SATA devices that appear under Linux-SCSI, but have not yet been updated to accept raw struct request
> operations directly. Some of these include TYPE_ROM, TYPE_TYPE and TYPE_MEDIUM_CHANGER hardware.
>
> This method can be used be used via ConfigFS as follows:
>
> export TARGET=/sys/kernel/config/target/core/
> # load target_core_mod
> modprobe target_core_mod
> # The Linux/SCSI scsi host id is part of pscsi_$HOST_ID HBA name..
> mkdir -p $TARGET/pscsi_0/sr0
> # echo CTL to the control configfs attribute
> echo scsi_channel_id=0,scsi_target_id=0,scsi_lun_id=0 > $TARGET/pscsi_0/sr0/control
> # Activate the target_core_mod/ConfigFS PSCSI storage object
> echo 1 > $TARGET/pscsi_0/sr0/enable
>
> At this point, creating symlinks for SCSI target ports to configfs enabled fabric modules
> against PSCSI hardware passthrough using te HCTL reference will work.
>
> This patch are made against lio-core-2.6.git/master and tested on
> v2.6.29 x86 32-bit HVM with TYPE_DISK and v2.6.29 ppc64 with TYPE_ROM.
> The lio-core-2.6.git tree can be found at:
>
> http://git.kernel.org/?p=linux/kernel/git/nab/lio-core-2.6.git;a=summary
>
> :-)
>

Are you aware that scsi_execute_async() has gone in 2.6.30-rc1?

I'm not sure what would be the best alternative for you. I would say
a bio, but it is still being debated. Your current options are:

1. bio_alloc then loop () bio_add_pc_page, and finally blk_rq_append_bio
(Which block people don't like)
2. sglist => page-pointers-array translation and blk_rq_map_user with
struct rq_map_data mode. (not possible with all kind of sglists)
2. sglist => iovec translation and blk_rq_map_user_iov()
(Very very ugly mapping of pages to virtual pointers)

I have a similar situation with my OSD code.

Boaz

> Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_pscsi.c | 88 +++++++++++++++++++++++++++++++-----
> include/target/target_core_pscsi.h | 2 +
> 2 files changed, 79 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
> index 0962563..66510f4 100644
> --- a/drivers/target/target_core_pscsi.c
> +++ b/drivers/target/target_core_pscsi.c
> @@ -399,6 +399,8 @@ void *pscsi_allocate_virtdevice(se_hba_t *hba, const char *name)
> return NULL;
> }
> pdv->pdv_se_hba = hba;
> + /* Use legacy path unless using ConfigFS FD method */
> + pdv->pdv_legacy = 1;
>
> printk(KERN_INFO "PSCSI: Allocated pdv: %p for %s\n", pdv, name);
> return (void *)pdv;
> @@ -555,9 +557,10 @@ int pscsi_activate_device(se_device_t *dev)
> struct scsi_device *sd = (struct scsi_device *) pdv->pdv_sd;
> struct Scsi_Host *sh = sd->host;
>
> - printk(KERN_INFO "CORE_PSCSI[%d] - Activating Device with TCQ: %d at"
> + printk(KERN_INFO "CORE_PSCSI[%d] - Activating %s Device with TCQ: %d at"
> " SCSI Location (Channel/Target/LUN) %d/%d/%d\n", sh->host_no,
> - sd->queue_depth, sd->channel, sd->id, sd->lun);
> + (pdv->pdv_legacy) ? "Legacy" : "REQ", sd->queue_depth,
> + sd->channel, sd->id, sd->lun);
>
> return 0;
> }
> @@ -572,8 +575,9 @@ void pscsi_deactivate_device(se_device_t *dev)
> struct scsi_device *sd = (struct scsi_device *) pdv->pdv_sd;
> struct Scsi_Host *sh = sd->host;
>
> - printk(KERN_INFO "CORE_PSCSI[%d] - Deactivating Device with TCQ: %d at"
> - " SCSI Location (Channel/Target/LUN) %d/%d/%d\n", sh->host_no,
> + printk(KERN_INFO "CORE_PSCSI[%d] - Deactivating %s Device with TCQ: %d"
> + " at SCSI Location (Channel/Target/LUN) %d/%d/%d\n",
> + sh->host_no, (pdv->pdv_legacy) ? "Legacy" : "REQ",
> sd->queue_depth, sd->channel, sd->id, sd->lun);
> }
>
> @@ -843,6 +847,30 @@ static int pscsi_blk_get_request(se_task_t *task)
> return 0;
> }
>
> +static int pscsi_do_task_legacy(
> + se_task_t *task,
> + pscsi_plugin_task_t *pt,
> + pscsi_dev_virt_t *pdv)
> +{
> + se_cmd_t *cmd = TASK_CMD(task);
> + void *pscsi_buf = (task->task_sg_num != 0) ? task->task_sg :
> + T_TASK(cmd)->t_task_buf;
> + int ret;
> +
> + ret = scsi_execute_async(pdv->pdv_sd, pt->pscsi_cdb,
> + COMMAND_SIZE(pt->pscsi_cdb[0]), pt->pscsi_direction,
> + pscsi_buf, task->task_size, task->task_sg_num,
> + (pdv->pdv_sd->type == TYPE_DISK) ? PS_TIMEOUT_DISK :
> + PS_TIMEOUT_OTHER, PS_RETRY, (void *)task,
> + pscsi_req_done_legacy, GFP_KERNEL);
> + if (ret != 0) {
> + printk(KERN_ERR "PSCSI Execute(): returned: %d\n", ret);
> + return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + }
> +
> + return 0;
> +}
> +
> /* pscsi_do_task(): (Part of se_subsystem_api_t template)
> *
> *
> @@ -852,6 +880,9 @@ int pscsi_do_task(se_task_t *task)
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
> struct gendisk *gd = NULL;
> +
> + if (pdv->pdv_legacy)
> + return pscsi_do_task_legacy(task, pt, pdv);
> /*
> * Grab pointer to struct gendisk for TYPE_DISK and TYPE_ROM
> * cases (eg: cases where struct scsi_device has a backing
> @@ -1104,6 +1135,7 @@ se_device_t *pscsi_create_virtdevice_from_fd(
> * Keep track of the struct block_device for now..
> */
> pdv->pdv_bd = bd;
> + pdv->pdv_legacy = 0;
> /*
> * pscsi_create_type_[disk,rom]() will release host_lock..
> */
> @@ -1286,6 +1318,9 @@ int pscsi_map_task_SG(se_task_t *task)
> PAGE_SIZE - 1) >> PAGE_SHIFT;
> int nr_vecs = 0, ret = 0;
>
> + if (pdv->pdv_legacy)
> + return 0;
> +
> if (!task->task_size)
> return 0;
> /*
> @@ -1387,6 +1422,9 @@ int pscsi_map_task_non_SG(se_task_t *task)
> pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
> int ret = 0;
>
> + if (pdv->pdv_legacy)
> + return 0;
> +
> if (!task->task_size)
> return 0;
>
> @@ -1407,8 +1445,12 @@ int pscsi_map_task_non_SG(se_task_t *task)
> int pscsi_CDB_inquiry(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_FROM_DEVICE;
> + if (pdv->pdv_legacy)
> + return pscsi_map_task_non_SG(task);
> +
> if (pscsi_blk_get_request(task) < 0)
> return -1;
>
> @@ -1418,10 +1460,11 @@ int pscsi_CDB_inquiry(se_task_t *task, u32 size)
> int pscsi_CDB_none(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_NONE;
>
> - return pscsi_blk_get_request(task);
> + return (pdv->pdv_legacy) ? 0 : pscsi_blk_get_request(task);
> }
>
> /* pscsi_CDB_read_non_SG():
> @@ -1431,8 +1474,11 @@ int pscsi_CDB_none(se_task_t *task, u32 size)
> int pscsi_CDB_read_non_SG(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_FROM_DEVICE;
> + if (pdv->pdv_legacy)
> + return pscsi_map_task_non_SG(task);
>
> if (pscsi_blk_get_request(task) < 0)
> return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> @@ -1447,11 +1493,13 @@ int pscsi_CDB_read_non_SG(se_task_t *task, u32 size)
> int pscsi_CDB_read_SG(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_FROM_DEVICE;
>
> - if (pscsi_blk_get_request(task) < 0)
> - return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + if (!(pdv->pdv_legacy))
> + if (pscsi_blk_get_request(task) < 0)
> + return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>
> if (pscsi_map_task_SG(task) < 0)
> return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> @@ -1466,11 +1514,13 @@ int pscsi_CDB_read_SG(se_task_t *task, u32 size)
> int pscsi_CDB_write_non_SG(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_TO_DEVICE;
>
> - if (pscsi_blk_get_request(task) < 0)
> - return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + if (!(pdv->pdv_legacy))
> + if (pscsi_blk_get_request(task) < 0)
> + return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>
> return pscsi_map_task_non_SG(task);
> }
> @@ -1482,11 +1532,13 @@ int pscsi_CDB_write_non_SG(se_task_t *task, u32 size)
> int pscsi_CDB_write_SG(se_task_t *task, u32 size)
> {
> pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
> + pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
>
> pt->pscsi_direction = DMA_TO_DEVICE;
>
> - if (pscsi_blk_get_request(task) < 0)
> - return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + if (!(pdv->pdv_legacy))
> + if (pscsi_blk_get_request(task) < 0)
> + return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>
> if (pscsi_map_task_SG(task) < 0)
> return PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> @@ -1643,6 +1695,20 @@ static inline void pscsi_process_SAM_status(
> return;
> }
>
> +void pscsi_req_done_legacy(void *data, char *sense, int result, int data_len)
> +{
> + se_task_t *task = (se_task_t *)data;
> + pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *)task->transport_req;
> +
> + pt->pscsi_result = result;
> + pt->pscsi_resid = data_len;
> +
> + if (result != 0)
> + memcpy(pt->pscsi_sense, sense, SCSI_SENSE_BUFFERSIZE);
> +
> + pscsi_process_SAM_status(task, pt);
> +}
> +
> void pscsi_req_done(struct request *req, int uptodate)
> {
> se_task_t *task = (se_task_t *)req->end_io_data;
> diff --git a/include/target/target_core_pscsi.h b/include/target/target_core_pscsi.h
> index b05b793..0e1d6cf 100644
> --- a/include/target/target_core_pscsi.h
> +++ b/include/target/target_core_pscsi.h
> @@ -94,6 +94,7 @@ extern u32 pscsi_get_dma_length(u32, se_device_t *);
> extern u32 pscsi_get_max_sectors(se_device_t *);
> extern u32 pscsi_get_queue_depth(se_device_t *);
> extern void pscsi_shutdown_hba(struct se_hba_s *);
> +extern void pscsi_req_done_legacy(void *, char *, int, int);
> extern void pscsi_req_done(struct request *, int);
> #endif
>
> @@ -120,6 +121,7 @@ typedef struct pscsi_plugin_task_s {
>
> typedef struct pscsi_dev_virt_s {
> int pdv_flags;
> + int pdv_legacy; /* Use scsi_execute_async() from HTCL */
> int pdv_channel_id;
> int pdv_target_id;
> int pdv_lun_id;

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Next message: Rafael J. Wysocki: "Re: [Bug #13068] Lockdep warining in inotify_dev_queue_event"
Previous message: Peter Zijlstra: "Re: [PATCH] Allow preemption during lazy mmu updates"
In reply to: Nicholas A. Bellinger: "[PATCH] [Target_Core_Mod/pSCSI]: Add optional legacyscsi_execute_async() usage for Linux/SCSI passthrough"
Next in thread: Nicholas A. Bellinger: "Re: [PATCH] [Target_Core_Mod/pSCSI]: Add optionallegacy scsi_execute_async() usage for Linux/SCSI passthrough"
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