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Date: Mon, 20 Sep 2010 01:54:37 -0700
From: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
To: Boaz Harrosh <bharrosh@...asas.com>
Cc: linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
James Bottomley <James.Bottomley@...e.de>,
Mike Christie <michaelc@...wisc.edu>,
FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
Hannes Reinecke <hare@...e.de>,
Konrad Rzeszutek Wilk <konrad@...nok.org>,
Douglas Gilbert <dgilbert@...erlog.com>,
Joe Eykholt <jeykholt@...co.com>
Subject: Re: [PATCH 1/3] tcm: Add native 32-byte CDB support
On Sun, 2010-09-19 at 13:55 +0200, Boaz Harrosh wrote:
> On 09/17/2010 07:34 AM, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@...ux-iscsi.org>
> >
> > This patch adds a '#define TCM_MAX_COMMAND_SIZE 32' and converts all
> > inline TCM core and subsystem CDB size defines to use TCM_MAX_COMMAND_SIZE
> > instead of the 16-byte MAX_COMMAND_SIZE. This includes the conversion of
> > MAX_COMMAND_SIZE in certain places to use include/scsi/scsi.h:scsi_command_size()
> > to properly extract the size of a received CDB based on opcode.
> >
> > This patch also includes the conversion of the FILEIO, IBLOCK, PSCSI, RAMDISK
> > and STGT subsystem modules to use TCM_MAX_COMMAND_SIZE for their default
> > internal inline CDB size.
> >
> > It also adds transport_lba_64_ext() and transport_get_sectors_32() callers
> > into target_core_transport.c to be used for extracting a 64-bit logical
> > block address and 32-bit transfer length (in block) from 32-byte CDBs.
> > Finally this patch adds split_cdb_XX_32() and split_cdb_XX_32() for handling
> > the generation of 32-byte CDBs for individual struct se_task.
> >
> > Signed-off-by: Nicholas A. Bellinger <nab@...ux-iscsi.org>
> > ---
> > drivers/target/target_core_file.h | 2 +-
> > drivers/target/target_core_iblock.h | 2 +-
> > drivers/target/target_core_pscsi.c | 2 +-
> > drivers/target/target_core_pscsi.h | 2 +-
> > drivers/target/target_core_rd.h | 2 +-
> > drivers/target/target_core_scdb.c | 38 +++++++++++++++++++++++++++
> > drivers/target/target_core_scdb.h | 2 +
> > drivers/target/target_core_stgt.h | 2 +-
> > drivers/target/target_core_transport.c | 44 ++++++++++++++++++++++++++++---
> > include/target/target_core_base.h | 13 +++++++++
> > 10 files changed, 98 insertions(+), 11 deletions(-)
> >
<SNIP>
> > diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
> > index 803853d..beca807 100644
> > --- a/drivers/target/target_core_pscsi.c
> > +++ b/drivers/target/target_core_pscsi.c
> > @@ -743,7 +743,7 @@ static inline void pscsi_blk_init_request(
> > * Load the referenced struct se_task's SCSI CDB into
> > * include/linux/blkdev.h:struct request->cmd
> > */
> > - pt->pscsi_req->cmd_len = COMMAND_SIZE(pt->pscsi_cdb[0]);
> > + pt->pscsi_req->cmd_len = scsi_command_size(pt->pscsi_cdb);
> > memcpy(pt->pscsi_req->cmd, pt->pscsi_cdb, pt->pscsi_req->cmd_len);
>
> Boom, only 16 bytes at req->cmd.
>
> For larger than 16 bytes commands at the block/scsi-ml level you need to:
>
> request->cmd = my_buffer_valid_until_complete;
> request->cmd_len = scsi_command_size()
>
> if above "my_buffer_valid_until_complet" is always available you can just
> do this regardless. If you need to dynamically allocate it (and deallocate)
> then you should do an if > MAX_COMMAND_SIZE
>
Hi Boaz,
I was pretty there was going to be some more work required on the
TCM/PSCSI case for proper > 16 byte support, thanks for spotting this
one.
So what I am thinking is that we can get rid of this memcpy() all
together and just always use the per struct se_task allocated struct
pscsi_plugin_task *pt->pscsi_cdb[] up to the new TCM_MAX_COMMAND_SIZE
(32 bytes) for the request->cmd pointer.
Is there anything special that needs to be done in order to singal that
struct request->cmd will be using *tp->pscsi_cdb[], and not struct
request->__cmd[BLK_MAX_CMD]..?
> > /*
> > * Setup pointer for outgoing sense data.
> > diff --git a/drivers/target/target_core_pscsi.h b/drivers/target/target_core_pscsi.h
> > index db09d6a..086e6f1 100644
> > --- a/drivers/target/target_core_pscsi.h
> > +++ b/drivers/target/target_core_pscsi.h
> > @@ -28,7 +28,7 @@ extern int linux_blockdevice_check(int, int);
> > #include <linux/kobject.h>
> >
> > struct pscsi_plugin_task {
> > - unsigned char pscsi_cdb[MAX_COMMAND_SIZE];
> > + unsigned char pscsi_cdb[TCM_MAX_COMMAND_SIZE];
> > unsigned char pscsi_sense[SCSI_SENSE_BUFFERSIZE];
> > int pscsi_direction;
> > int pscsi_result;
>
> pscsi is when you directly Q to a scsi LLD via midlayer right? Note that most
> scsi LLDs don't support > 16 or 12 bytes. The regular scsi despatch will check
> this for you and return an error. How are these dispatched? blk_execute_rq* ?
>
Correct on both points. So all control path CDBs with PSCSI are treated
as a passthrough. The one special thing about pSCSI and struct request
passthrough is wrt SCF_SCSI_DATA_SG_IO_CDB I/Os is that TCM Core will
still handle the 1 -> N mapping of TCM struct se_task->task_sg[] across
a single struct se_cmd->t_mem_list for received CDB sectors > underying
HW max_sectors limitiations reported by pscsi_get_max_sectors().
> > diff --git a/drivers/target/target_core_rd.h b/drivers/target/target_core_rd.h
> > index 8170b41..2008807 100644
> > --- a/drivers/target/target_core_rd.h
> > +++ b/drivers/target/target_core_rd.h
> > @@ -31,7 +31,7 @@ void rd_module_exit(void);
> >
> > struct rd_request {
> > /* SCSI CDB from iSCSI Command PDU */
> > - unsigned char rd_scsi_cdb[MAX_COMMAND_SIZE];
> > + unsigned char rd_scsi_cdb[TCM_MAX_COMMAND_SIZE];
> > /* Data Direction */
> > u8 rd_data_direction;
> > /* Total length of request */
> > diff --git a/drivers/target/target_core_scdb.c b/drivers/target/target_core_scdb.c
> > index 8bcfeaf..76a7de0 100644
> > --- a/drivers/target/target_core_scdb.c
> > +++ b/drivers/target/target_core_scdb.c
> > @@ -28,6 +28,7 @@
> >
> > #include <linux/net.h>
> > #include <linux/string.h>
> > +#include <scsi/scsi.h>
> >
> > #include <target/target_core_base.h>
> > #include <target/target_core_transport.h>
> > @@ -147,3 +148,40 @@ void split_cdb_RW_16(
> > cdb[0] = (rw) ? 0x8a : 0x88;
> > split_cdb_XX_16(lba, sectors, &cdb[0]);
> > }
> > +
> > +/*
> > + * split_cdb_XX_32():
> > + *
> > + * 64-bit LBA w/ 32-bit SECTORS such as READ_32, WRITE_32 and XDWRITEREAD_32
> > + */
> > +void split_cdb_XX_32(
> > + unsigned long long lba,
> > + u32 *sectors,
> > + unsigned char *cdb)
> > +{
> > + cdb[12] = (lba >> 56) & 0xff;
> > + cdb[13] = (lba >> 48) & 0xff;
> > + cdb[14] = (lba >> 40) & 0xff;
> > + cdb[15] = (lba >> 32) & 0xff;
> > + cdb[16] = (lba >> 24) & 0xff;
> > + cdb[17] = (lba >> 16) & 0xff;
> > + cdb[18] = (lba >> 8) & 0xff;
> > + cdb[19] = lba & 0xff;
>
> put_unaligned_be64
Ok, converting all functions these in target_core_scdb.c to use
put_unaligned_be*().
>
> > + cdb[28] = (*sectors >> 24) & 0xff;
> > + cdb[29] = (*sectors >> 16) & 0xff;
> > + cdb[30] = (*sectors >> 8) & 0xff;
> > + cdb[31] = *sectors & 0xff;
>
> put_unaligned_be32
<nod>
> > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> > index 49d5946..a3016f7 100644
> > --- a/drivers/target/target_core_transport.c
> > +++ b/drivers/target/target_core_transport.c
> > @@ -2636,7 +2636,8 @@ static int transport_process_control_sg_transform(
> >
> > cdb = TRANSPORT(dev)->get_cdb(task);
> > if (cdb)
> > - memcpy(cdb, T_TASK(cmd)->t_task_cdb, MAX_COMMAND_SIZE);
> > + memcpy(cdb, T_TASK(cmd)->t_task_cdb,
> > + scsi_command_size(T_TASK(cmd)->t_task_cdb));
> >
> > task->task_size = cmd->data_length;
> > task->task_sg_num = 1;
> > @@ -2677,7 +2678,8 @@ static int transport_process_control_nonsg_transform(
> >
> > cdb = TRANSPORT(dev)->get_cdb(task);
> > if (cdb)
> > - memcpy(cdb, T_TASK(cmd)->t_task_cdb, MAX_COMMAND_SIZE);
> > + memcpy(cdb, T_TASK(cmd)->t_task_cdb,
> > + scsi_command_size(T_TASK(cmd)->t_task_cdb));
> >
> > task->task_size = cmd->data_length;
> > task->task_sg_num = 0;
> > @@ -2711,7 +2713,8 @@ static int transport_process_non_data_transform(
> >
> > cdb = TRANSPORT(dev)->get_cdb(task);
> > if (cdb)
> > - memcpy(cdb, T_TASK(cmd)->t_task_cdb, MAX_COMMAND_SIZE);
> > + memcpy(cdb, T_TASK(cmd)->t_task_cdb,
> > + scsi_command_size(T_TASK(cmd)->t_task_cdb));
> >
> > task->task_size = cmd->data_length;
> > task->task_sg_num = 0;
> > @@ -2902,7 +2905,7 @@ int transport_generic_allocate_tasks(
> > /*
> > * Copy the original CDB into T_TASK(cmd).
> > */
> > - memcpy(T_TASK(cmd)->t_task_cdb, cdb, MAX_COMMAND_SIZE);
> > + memcpy(T_TASK(cmd)->t_task_cdb, cdb, scsi_command_size(cdb));
>
> scsi_command_size can return up to 260 dependent on command. So you'll
> need a min() to make sure. I'd do a tsk_cdb_cpy() wrapper that does
> the proper min() for everyone. Later that wrapper can be made smarter
> for large commands up to 260.
Hmmm actually, I am wondering if we need a method for the individual
backstore to report the maximum supported CDB size on a TCM subsystem
plugin basis, say via a caller include/target/target_core_transport.h:
struct se_subsystem_api, and fail the extended CDB at TCM level for the
pSCSI cases where struct scsi_host->max_cmd_len < scsi_command_size().
Also wrt to 260 byte CDBs for TCM/pSCSI and really everything received
greater than the new default 32 for TCM_MAX_COMMAND_SIZE, this will
require the extra allocation by TCM Core at both the
T_TASK(cmd)->t_task_cdb[] as well as allowing pSCSI to handle this case.
I will look at implementing this soon, but I still need a way to test
this code with TCM/PSCSI and scsi_debug.. Any ideas on where to look
for doing this with > 32 byte CDBs..?
>
> > /*
> > * Check for SAM Task Attribute Emulation
> > */
> > @@ -3829,6 +3832,19 @@ static inline unsigned long long transport_lba_64(unsigned char *cdb)
> > return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
> > }
> >
> > +/*
> > + * For VARIABLE_LENGTH_CDB w/ 32 byte extended CDBs
> > + */
> > +static inline unsigned long long transport_lba_64_ext(unsigned char *cdb)
> > +{
> > + unsigned int __v1, __v2;
> > +
> > + __v1 = (cdb[12] << 24) | (cdb[13] << 16) | (cdb[14] << 8) | cdb[15];
> > + __v2 = (cdb[16] << 24) | (cdb[17] << 16) | (cdb[18] << 8) | cdb[19];
> > +
> > + return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
>
> get_unaligned_be64(&cdb[12]);
>
> I'd just drop this wrapper
Good point, I believe this is only used in a single location.
transport_generic_allocate_tasks().
>
> > +}
> > +
> > /* transport_set_supported_SAM_opcode():
> > *
> > *
> > @@ -4370,6 +4386,23 @@ type_disk:
> > (cdb[12] << 8) + cdb[13];
> > }
> >
> > +/*
> > + * Used for VARIABLE_LENGTH_CDB WRITE_32 and READ_32 variants
> > + */
> > +static inline u32 transport_get_sectors_32(
> > + unsigned char *cdb,
> > + struct se_cmd *cmd,
> > + int *ret)
> > +{
> > + /*
> > + * Assume TYPE_DISK for non struct se_device objects.
> > + * Use 32-bit sector value.
> > + */
> > + return (u32)(cdb[28] << 24) + (cdb[29] << 16) +
> > + (cdb[30] << 8) + cdb[31];
> > +
>
> get_unaligned_be32
Ok, there are a few more of these that can be converted to
get_unaligned_be*() and friends.
Thanks for your comments Boaz!
--nab
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