Based on "[PATH V2] scsi_debug: rework resp_report_luns" patch
sent by Tomas Winkler on Thursday, 26 Feb 2015. His notes:
1. Remove duplicated boundary checks which simplify the fill-in
loop
2. Use more of scsi generic API
Replace fixed length response array a with heap allocation
allowing up to 16383 LUNs per target.
Signed-off-by: Douglas Gilbert <dgilb...@interlog.com>
---
drivers/scsi/scsi_debug.c | 138 ++++++++++++++++++++++++++++++----------------
1 file changed, 91 insertions(+), 47 deletions(-)
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index cf44ab0..eac62b8 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -3205,63 +3205,99 @@ static int resp_get_lba_status(struct scsi_cmnd *scp,
return fill_from_dev_buffer(scp, arr, SDEBUG_GET_LBA_STATUS_LEN);
}
-#define SDEBUG_RLUN_ARR_SZ 256
-
-static int resp_report_luns(struct scsi_cmnd * scp,
- struct sdebug_dev_info * devip)
+/* Even though each pseudo target has a REPORT LUNS "well known logical unit"
+ * (W-LUN), the normal Linux scanning logic does not associate it with a
+ * device (e.g. /dev/sg7). The following magic will make that association:
+ * "cd /sys/class/scsi_host/host<n> ; echo '- - 49409' > scan"
+ * where <n> is a host number. If there are multiple targets in a host then
+ * the above will associate a W-LUN to each target. To only get a W-LUN
+ * for target 2, then use "echo '- 2 49409' > scan" . */
+static int resp_report_luns(struct scsi_cmnd *scp,
+ struct sdebug_dev_info *devip)
{
+ unsigned char *cmd = scp->cmnd;
unsigned int alloc_len;
- int lun_cnt, i, upper, num, n, want_wlun, shortish;
+ unsigned char select_report;
u64 lun;
- unsigned char *cmd = scp->cmnd;
- int select_report = (int)cmd[2];
- struct scsi_lun *one_lun;
- unsigned char arr[SDEBUG_RLUN_ARR_SZ];
- unsigned char * max_addr;
+ struct scsi_lun *lun_p;
+ u8 *arr;
+ unsigned int lun_cnt; /* normal LUN count (max: 16383) */
+ unsigned int wlun_cnt; /* report luns W-LUN count */
+ unsigned int tlun_cnt; /* total LUN count */
+ unsigned int rlen; /* response length (in bytes) less header */
+ int i, res;
clear_luns_changed_on_target(devip);
- alloc_len = cmd[9] + (cmd[8] << 8) + (cmd[7] << 16) + (cmd[6] << 24);
- shortish = (alloc_len < 4);
- if (shortish || (select_report > 2)) {
- mk_sense_invalid_fld(scp, SDEB_IN_CDB, shortish ? 6 : 2, -1);
+
+ select_report = cmd[2];
+ alloc_len = get_unaligned_be32(cmd + 6);
+
+ if (alloc_len < 4) {
+ pr_err("alloc len too small %d\n", alloc_len);
+ mk_sense_invalid_fld(scp, SDEB_IN_CDB, 6, -1);
return check_condition_result;
}
- /* can produce response with up to 16k luns (lun 0 to lun 16383) */
- memset(arr, 0, SDEBUG_RLUN_ARR_SZ);
+
+ if (select_report > 0x02) {
+ pr_err("select report invalid %d\n", select_report);
+ mk_sense_invalid_fld(scp, SDEB_IN_CDB, 2, -1);
+ return check_condition_result;
+ }
+
lun_cnt = sdebug_max_luns;
- if (1 == select_report)
+ wlun_cnt = 0;
+
+ /* report only w_lun */
+ if (select_report == 0x01)
lun_cnt = 0;
- else if (sdebug_no_lun_0 && (lun_cnt > 0))
+
+ if (sdebug_no_lun_0 && (lun_cnt > 0))
--lun_cnt;
- want_wlun = (select_report > 0) ? 1 : 0;
- num = lun_cnt + want_wlun;
- arr[2] = ((sizeof(struct scsi_lun) * num) >> 8) & 0xff;
- arr[3] = (sizeof(struct scsi_lun) * num) & 0xff;
- n = min((int)((SDEBUG_RLUN_ARR_SZ - 8) /
- sizeof(struct scsi_lun)), num);
- if (n < num) {
- want_wlun = 0;
- lun_cnt = n;
- }
- one_lun = (struct scsi_lun *) &arr[8];
- max_addr = arr + SDEBUG_RLUN_ARR_SZ;
- for (i = 0, lun = (sdebug_no_lun_0 ? 1 : 0);
- ((i < lun_cnt) && ((unsigned char *)(one_lun + i) < max_addr));
- i++, lun++) {
- upper = (lun >> 8) & 0x3f;
- if (upper)
- one_lun[i].scsi_lun[0] =
- (upper | (SAM2_LUN_ADDRESS_METHOD << 6));
- one_lun[i].scsi_lun[1] = lun & 0xff;
- }
- if (want_wlun) {
- one_lun[i].scsi_lun[0] = (SCSI_W_LUN_REPORT_LUNS >> 8) & 0xff;
- one_lun[i].scsi_lun[1] = SCSI_W_LUN_REPORT_LUNS & 0xff;
- i++;
- }
- alloc_len = (unsigned char *)(one_lun + i) - arr;
- return fill_from_dev_buffer(scp, arr,
- min((int)alloc_len, SDEBUG_RLUN_ARR_SZ));
+
+ /* report w_lun */
+ if (select_report == 0x01 || select_report == 0x02)
+ wlun_cnt = 1;
+
+ tlun_cnt = lun_cnt + wlun_cnt;
+ /* can produce response with up to 16k luns (lun 0 to lun 16383) */
+ arr = kzalloc((tlun_cnt * sizeof(lun_p->scsi_lun)) + 8, GFP_ATOMIC);
+ if (!arr) {
+ pr_warn("No space for report luns response\n");
+ mk_sense_buffer(scp, ILLEGAL_REQUEST, INSUFF_RES_ASC,
+ INSUFF_RES_ASCQ);
+ return check_condition_result;
+ }
+ pr_debug("select_report %d luns = %d wluns = %d no_lun0 %d\n",
+ select_report, lun_cnt, wlun_cnt, sdebug_no_lun_0);
+
+ lun = 0LL;
+ /* luns start at offset 8 after the byte length */
+ lun_p = (struct scsi_lun *)&arr[8];
+
+ /* skip lun 0 */
+ if (sdebug_no_lun_0)
+ lun++;
+ /*
+ * Address method (we use Peripherial = 00b)
+ * 10b - Logical unit
+ * 00b - Peripherial device - Use this one
+ * 01b - Logical device
+ * 11b - reserved
+ */
+ for (i = 0; i < lun_cnt; i++)
+ int_to_scsilun(lun++, lun_p++);
+
+ /* report SCSI_W_LUN_REPORT_LUN */
+ if (wlun_cnt)
+ int_to_scsilun(SCSI_W_LUN_REPORT_LUNS, lun_p++);
+
+ rlen = tlun_cnt * sizeof(struct scsi_lun);
+
+ put_unaligned_be32(rlen, &arr[0]);
+
+ res = fill_from_dev_buffer(scp, arr, rlen + 8);
+ kfree(arr);
+ return res;
}
static int resp_xdwriteread(struct scsi_cmnd *scp, unsigned long long lba,
@@ -4299,6 +4335,10 @@ static ssize_t max_luns_store(struct device_driver *ddp,
const char *buf,
bool changed;
if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n >= 0)) {
+ if (n > 16383) {
+ pr_warn("max_luns can be no more than 16383\n");
+ return -EINVAL;
+ }
changed = (sdebug_max_luns != n);
sdebug_max_luns = n;
sdebug_max_tgts_luns();
@@ -4643,6 +4683,10 @@ static int __init scsi_debug_init(void)
pr_err("invalid physblk_exp %u\n", sdebug_physblk_exp);
return -EINVAL;
}
+ if (sdebug_max_luns > 16383) {
+ pr_warn("max_luns can be no more than 16383, use default\n");
+ sdebug_max_luns = DEF_MAX_LUNS;
+ }
if (sdebug_lowest_aligned > 0x3fff) {
pr_err("lowest_aligned too big: %u\n", sdebug_lowest_aligned);
