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scst_lib: Allow REPORT LUNS to operate on an unsupported LUN #223

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May 3, 2024
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scst_lib: Allow REPORT LUNS to operate on an unsupported LUN #223

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143 changes: 143 additions & 0 deletions scst/src/scst_lib.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,9 @@
#include "scst_mem.h"
#include "scst_pres.h"

/* 8 byte ASCII Vendor */
#define SCST_NOLUN_VENDOR "SCST "

/*
* List and IRQ lock to globally serialize all STPG commands. Needed to
* prevent deadlock, if (1) a device group contains multiple devices and
Expand Down Expand Up @@ -1919,6 +1922,10 @@ static int scst_set_lun_not_supported_inquiry(struct scst_cmd *cmd)
buf[2] = 6; /* Device complies to SPC-4 */
buf[4] = len - 4;

/* Set T10 Vendor identification */
if (len >= 16)
memcpy(&(buf[8]), SCST_NOLUN_VENDOR, 8);

TRACE_BUFFER("INQUIRY for not supported LUN set", buf, len);

cmd->data_direction = SCST_DATA_READ;
Expand All @@ -1933,6 +1940,140 @@ static int scst_set_lun_not_supported_inquiry(struct scst_cmd *cmd)
return res;
}

static int scst_set_lun_not_supported_report_luns(struct scst_cmd *cmd)
{
uint8_t *buf;
int dev_cnt = 0;
struct scatterlist *sg;
struct scst_tgt_dev *tgt_dev = NULL;
int i, len;
int res = 0;
int offs, overflow = 0;

TRACE_ENTRY();

if (cmd->status != 0) {
TRACE_MGMT_DBG("cmd %p already has status %x set",
cmd, cmd->status);
res = -EEXIST;
goto out;
}

if ((cmd->cdb[2] != 0) && (cmd->cdb[2] != 2)) {
TRACE(TRACE_MINOR,
"Unsupported SELECT REPORT value %#x in REPORT LUNS command",
cmd->cdb[2]);
scst_set_invalid_field_in_cdb(cmd, 2, 0);
goto out;
}

if (cmd->sg == NULL) {
if (cmd->bufflen == 0) {
int bufflen = get_unaligned_be32(&cmd->cdb[6]);

cmd->bufflen = bufflen ? max_t(int, 8, bufflen) : 8;
}

/*
* If target driver preparing data buffer using tgt_alloc_data_buf()
* callback, it is responsible to copy the sense to its buffer
* in xmit_response().
*/
if (cmd->tgt_i_data_buf_alloced && (cmd->tgt_i_sg != NULL)) {
cmd->sg = cmd->tgt_i_sg;
cmd->sg_cnt = cmd->tgt_i_sg_cnt;
TRACE_MEM("Tgt used for REPORTS LUNS (not supported LUN): cmd %p",
cmd);
goto go;
}

cmd->sg = scst_alloc_sg(cmd->bufflen, GFP_ATOMIC, &cmd->sg_cnt);
if (cmd->sg == NULL) {
PRINT_ERROR("Unable to alloc sg for REPORTS LUNS (not supported LUN)");
res = 1;
goto out;
}

TRACE_MEM(
"sg %p (cnt %d, len %d) allocated for REPORTS LUNS (not supported LUN): cmd %p",
cmd->sg, cmd->sg_cnt, cmd->bufflen, cmd);
}

go:
sg = cmd->sg;
len = sg->length;

TRACE_MEM("sg %p (len %d) for REPORTS LUNS for cmd %p", sg, len, cmd);

buf = sg_virt(sg);
len = max_t(int, 8, len);

memset(buf, 0, len);
offs = 8;

rcu_read_lock();
for (i = 0; i < SESS_TGT_DEV_LIST_HASH_SIZE; i++) {
struct list_head *head = &cmd->sess->sess_tgt_dev_list[i];

list_for_each_entry_rcu(tgt_dev, head,
sess_tgt_dev_list_entry) {
struct scst_tgt_dev_UA *ua;

if (!overflow) {
if ((len - offs) < 8) {
overflow = 1;
goto inc_dev_cnt;
}
*(__force __be64 *)&buf[offs]
= scst_pack_lun(tgt_dev->lun,
cmd->sess->acg->addr_method);
offs += 8;
}
inc_dev_cnt:
dev_cnt++;

/* Clear sense_reported_luns_data_changed UA. */
spin_lock_bh(&tgt_dev->tgt_dev_lock);
list_for_each_entry(ua, &tgt_dev->UA_list,
UA_list_entry) {
if (scst_analyze_sense(ua->UA_sense_buffer,
ua->UA_valid_sense_len,
SCST_SENSE_ALL_VALID,
SCST_LOAD_SENSE(scst_sense_reported_luns_data_changed))) {
TRACE_DBG(
"Freeing not needed REPORTED LUNS DATA CHANGED UA %p",
ua);
scst_tgt_dev_del_free_UA(tgt_dev, ua);
break;
}
}
spin_unlock_bh(&tgt_dev->tgt_dev_lock);
}
}
rcu_read_unlock();

/* Set the response header */
dev_cnt *= 8;
put_unaligned_be32(dev_cnt, buf);

dev_cnt += 8;
if (dev_cnt < len)
len = dev_cnt;

TRACE_BUFFER("REPORTS LUNS for not supported LUN set", buf, len);

cmd->data_direction = SCST_DATA_READ;
scst_set_resp_data_len(cmd, len);

cmd->completed = 1;
cmd->resid_possible = 1;

out:
TRACE_EXIT_RES(res);

return res;
}

/*
* scst_set_cmd_error() - set error in the command and fill the sense buffer.
*
Expand All @@ -1955,6 +2096,8 @@ int scst_set_cmd_error(struct scst_cmd *cmd, int key, int asc, int ascq)
key, asc, ascq);
else if (cmd->cdb[0] == INQUIRY)
res = scst_set_lun_not_supported_inquiry(cmd);
else if (cmd->cdb[0] == REPORT_LUNS)
res = scst_set_lun_not_supported_report_luns(cmd);
else
goto do_sense;

Expand Down