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target: Add WRITE_SAME (10) parsing and refactor passthrough checks
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This patch adds initial WRITE_SAME (10) w/ UNMAP=1 support following updates in
sbcr26 to allow UNMAP=1 for the non 16 + 32 byte CDB case.  It also refactors
current pSCSI passthrough passthrough checks into target_check_write_same_discard()
ahead of UNMAP=0 w/ write payload support into target_core_iblock.c.

This includes the support for handling WRITE_SAME in transport_emulate_control_cdb(),
and converts target_emulate_write_same to accept num_blocks directly for
WRITE_SAME, WRITE_SAME_16 and WRITE_SAME_32.

Reported-by: Eric Seppanen <eric@purestorage.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@risingtidesystems.com>
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Nicholas Bellinger committed Aug 22, 2011
1 parent 16ab8e6 commit 706d586
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Showing 2 changed files with 73 additions and 57 deletions.
28 changes: 16 additions & 12 deletions drivers/target/target_core_cdb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1090,24 +1090,17 @@ target_emulate_unmap(struct se_task *task)
* Note this is not used for TCM/pSCSI passthrough
*/
static int
target_emulate_write_same(struct se_task *task, int write_same32)
target_emulate_write_same(struct se_task *task, u32 num_blocks)
{
struct se_cmd *cmd = task->task_se_cmd;
struct se_device *dev = cmd->se_dev;
sector_t range;
sector_t lba = cmd->t_task_lba;
unsigned int num_blocks;
int ret;
/*
* Extract num_blocks from the WRITE_SAME_* CDB. Then use the explict
* range when non zero is supplied, otherwise calculate the remaining
* range based on ->get_blocks() - starting LBA.
* Use the explicit range when non zero is supplied, otherwise calculate
* the remaining range based on ->get_blocks() - starting LBA.
*/
if (write_same32)
num_blocks = get_unaligned_be32(&cmd->t_task_cdb[28]);
else
num_blocks = get_unaligned_be32(&cmd->t_task_cdb[10]);

if (num_blocks != 0)
range = num_blocks;
else
Expand Down Expand Up @@ -1170,13 +1163,23 @@ transport_emulate_control_cdb(struct se_task *task)
}
ret = target_emulate_unmap(task);
break;
case WRITE_SAME:
if (!dev->transport->do_discard) {
pr_err("WRITE_SAME emulation not supported"
" for: %s\n", dev->transport->name);
return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
}
ret = target_emulate_write_same(task,
get_unaligned_be16(&cmd->t_task_cdb[7]));
break;
case WRITE_SAME_16:
if (!dev->transport->do_discard) {
pr_err("WRITE_SAME_16 emulation not supported"
" for: %s\n", dev->transport->name);
return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
}
ret = target_emulate_write_same(task, 0);
ret = target_emulate_write_same(task,
get_unaligned_be32(&cmd->t_task_cdb[10]));
break;
case VARIABLE_LENGTH_CMD:
service_action =
Expand All @@ -1189,7 +1192,8 @@ transport_emulate_control_cdb(struct se_task *task)
dev->transport->name);
return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
}
ret = target_emulate_write_same(task, 1);
ret = target_emulate_write_same(task,
get_unaligned_be32(&cmd->t_task_cdb[28]));
break;
default:
pr_err("Unsupported VARIABLE_LENGTH_CMD SA:"
Expand Down
102 changes: 57 additions & 45 deletions drivers/target/target_core_transport.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2861,6 +2861,38 @@ static int transport_cmd_get_valid_sectors(struct se_cmd *cmd)
return sectors;
}

static int target_check_write_same_discard(unsigned char *flags, struct se_device *dev)
{
/*
* Determine if the received WRITE_SAME is used to for direct
* passthrough into Linux/SCSI with struct request via TCM/pSCSI
* or we are signaling the use of internal WRITE_SAME + UNMAP=1
* emulation for -> Linux/BLOCK disbard with TCM/IBLOCK code.
*/
int passthrough = (dev->transport->transport_type ==
TRANSPORT_PLUGIN_PHBA_PDEV);

if (!passthrough) {
if ((flags[0] & 0x04) || (flags[0] & 0x02)) {
pr_err("WRITE_SAME PBDATA and LBDATA"
" bits not supported for Block Discard"
" Emulation\n");
return -ENOSYS;
}
/*
* Currently for the emulated case we only accept
* tpws with the UNMAP=1 bit set.
*/
if (!(flags[0] & 0x08)) {
pr_err("WRITE_SAME w/o UNMAP bit not"
" supported for Block Discard Emulation\n");
return -ENOSYS;
}
}

return 0;
}

/* transport_generic_cmd_sequencer():
*
* Generic Command Sequencer that should work for most DAS transport
Expand Down Expand Up @@ -3081,27 +3113,9 @@ static int transport_generic_cmd_sequencer(
cmd->t_task_lba = get_unaligned_be64(&cdb[12]);
cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;

/*
* Skip the remaining assignments for TCM/PSCSI passthrough
*/
if (passthrough)
break;

if ((cdb[10] & 0x04) || (cdb[10] & 0x02)) {
pr_err("WRITE_SAME PBDATA and LBDATA"
" bits not supported for Block Discard"
" Emulation\n");
if (target_check_write_same_discard(&cdb[10], dev) < 0)
goto out_invalid_cdb_field;
}
/*
* Currently for the emulated case we only accept
* tpws with the UNMAP=1 bit set.
*/
if (!(cdb[10] & 0x08)) {
pr_err("WRITE_SAME w/o UNMAP bit not"
" supported for Block Discard Emulation\n");
goto out_invalid_cdb_field;
}

break;
default:
pr_err("VARIABLE_LENGTH_CMD service action"
Expand Down Expand Up @@ -3358,33 +3372,31 @@ static int transport_generic_cmd_sequencer(
}

cmd->t_task_lba = get_unaligned_be64(&cdb[2]);
passthrough = (dev->transport->transport_type ==
TRANSPORT_PLUGIN_PHBA_PDEV);
/*
* Determine if the received WRITE_SAME_16 is used to for direct
* passthrough into Linux/SCSI with struct request via TCM/pSCSI
* or we are signaling the use of internal WRITE_SAME + UNMAP=1
* emulation for -> Linux/BLOCK disbard with TCM/IBLOCK and
* TCM/FILEIO subsystem plugin backstores.
*/
if (!passthrough) {
if ((cdb[1] & 0x04) || (cdb[1] & 0x02)) {
pr_err("WRITE_SAME PBDATA and LBDATA"
" bits not supported for Block Discard"
" Emulation\n");
goto out_invalid_cdb_field;
}
/*
* Currently for the emulated case we only accept
* tpws with the UNMAP=1 bit set.
*/
if (!(cdb[1] & 0x08)) {
pr_err("WRITE_SAME w/o UNMAP bit not "
" supported for Block Discard Emulation\n");
goto out_invalid_cdb_field;
}
cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;

if (target_check_write_same_discard(&cdb[1], dev) < 0)
goto out_invalid_cdb_field;
break;
case WRITE_SAME:
sectors = transport_get_sectors_10(cdb, cmd, &sector_ret);
if (sector_ret)
goto out_unsupported_cdb;

if (sectors)
size = transport_get_size(sectors, cdb, cmd);
else {
pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not supported\n");
goto out_invalid_cdb_field;
}

cmd->t_task_lba = get_unaligned_be32(&cdb[2]);
cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;
/*
* Follow sbcr26 with WRITE_SAME (10) and check for the existence
* of byte 1 bit 3 UNMAP instead of original reserved field
*/
if (target_check_write_same_discard(&cdb[1], dev) < 0)
goto out_invalid_cdb_field;
break;
case ALLOW_MEDIUM_REMOVAL:
case GPCMD_CLOSE_TRACK:
Expand Down

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