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authorLee Duncan <lduncan@suse.com>2018-05-15 18:25:24 -0700
committerMartin K. Petersen <martin.petersen@oracle.com>2018-05-18 12:22:48 -0400
commitbd81372065fa467e262150c70be885f47f9535df (patch)
treedfa782e8a1a792f76ca14dffb4b224c6174abebd /drivers/target
parent51b910c3c70986a5a0a84eea11cb8e904e37ba8b (diff)
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scsi: target: transport should handle st FM/EOM/ILI reads
When a tape drive is exported via LIO using the pscsi module, a read that requests more bytes per block than the tape can supply returns an empty buffer. This is because the pscsi pass-through target module sees the "ILI" illegal length bit set and thinks there is no reason to return the data. This is a long-standing transport issue, since it assumes that no data need be returned under a check condition, which isn't always the case for tape. Add in a check for tape reads with the ILI, EOM, or FM bits set, with a sense code of NO_SENSE, treating such cases as if the read succeeded. The layered tape driver then "does the right thing" when it gets such a response. Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: Lee Duncan <lduncan@suse.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/target')
-rw-r--r--drivers/target/target_core_pscsi.c26
-rw-r--r--drivers/target/target_core_transport.c43
2 files changed, 61 insertions, 8 deletions
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 0d99b242e82e..f31215b1d009 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -689,8 +689,29 @@ after_mode_sense:
}
after_mode_select:
- if (scsi_status == SAM_STAT_CHECK_CONDITION)
+ if (scsi_status == SAM_STAT_CHECK_CONDITION) {
transport_copy_sense_to_cmd(cmd, req_sense);
+
+ /*
+ * check for TAPE device reads with
+ * FM/EOM/ILI set, so that we can get data
+ * back despite framework assumption that a
+ * check condition means there is no data
+ */
+ if (sd->type == TYPE_TAPE &&
+ cmd->data_direction == DMA_FROM_DEVICE) {
+ /*
+ * is sense data valid, fixed format,
+ * and have FM, EOM, or ILI set?
+ */
+ if (req_sense[0] == 0xf0 && /* valid, fixed format */
+ req_sense[2] & 0xe0 && /* FM, EOM, or ILI */
+ (req_sense[2] & 0xf) == 0) { /* key==NO_SENSE */
+ pr_debug("Tape FM/EOM/ILI status detected. Treat as normal read.\n");
+ cmd->se_cmd_flags |= SCF_TREAT_READ_AS_NORMAL;
+ }
+ }
+ }
}
enum {
@@ -1061,7 +1082,8 @@ static void pscsi_req_done(struct request *req, blk_status_t status)
switch (host_byte(result)) {
case DID_OK:
- target_complete_cmd(cmd, scsi_status);
+ target_complete_cmd_with_length(cmd, scsi_status,
+ cmd->data_length - scsi_req(req)->resid_len);
break;
default:
pr_debug("PSCSI Host Byte exception at cmd: %p CDB:"
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 3500aa5927f2..bde14f46ed5b 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -779,7 +779,9 @@ EXPORT_SYMBOL(target_complete_cmd);
void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
{
- if (scsi_status == SAM_STAT_GOOD && length < cmd->data_length) {
+ if ((scsi_status == SAM_STAT_GOOD ||
+ cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL) &&
+ length < cmd->data_length) {
if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
cmd->residual_count += cmd->data_length - length;
} else {
@@ -2084,12 +2086,24 @@ static void transport_complete_qf(struct se_cmd *cmd)
goto queue_status;
}
- if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
+ /*
+ * Check if we need to send a sense buffer from
+ * the struct se_cmd in question. We do NOT want
+ * to take this path of the IO has been marked as
+ * needing to be treated like a "normal read". This
+ * is the case if it's a tape read, and either the
+ * FM, EOM, or ILI bits are set, but there is no
+ * sense data.
+ */
+ if (!(cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL) &&
+ cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
goto queue_status;
switch (cmd->data_direction) {
case DMA_FROM_DEVICE:
- if (cmd->scsi_status)
+ /* queue status if not treating this as a normal read */
+ if (cmd->scsi_status &&
+ !(cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL))
goto queue_status;
trace_target_cmd_complete(cmd);
@@ -2194,9 +2208,15 @@ static void target_complete_ok_work(struct work_struct *work)
/*
* Check if we need to send a sense buffer from
- * the struct se_cmd in question.
+ * the struct se_cmd in question. We do NOT want
+ * to take this path of the IO has been marked as
+ * needing to be treated like a "normal read". This
+ * is the case if it's a tape read, and either the
+ * FM, EOM, or ILI bits are set, but there is no
+ * sense data.
*/
- if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) {
+ if (!(cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL) &&
+ cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) {
WARN_ON(!cmd->scsi_status);
ret = transport_send_check_condition_and_sense(
cmd, 0, 1);
@@ -2238,7 +2258,18 @@ static void target_complete_ok_work(struct work_struct *work)
queue_rsp:
switch (cmd->data_direction) {
case DMA_FROM_DEVICE:
- if (cmd->scsi_status)
+ /*
+ * if this is a READ-type IO, but SCSI status
+ * is set, then skip returning data and just
+ * return the status -- unless this IO is marked
+ * as needing to be treated as a normal read,
+ * in which case we want to go ahead and return
+ * the data. This happens, for example, for tape
+ * reads with the FM, EOM, or ILI bits set, with
+ * no sense data.
+ */
+ if (cmd->scsi_status &&
+ !(cmd->se_cmd_flags & SCF_TREAT_READ_AS_NORMAL))
goto queue_status;
atomic_long_add(cmd->data_length,