ChangeLog:
- add comments to scsi_end_request() noting what its bool return
value means
- change some variable names in scsi_io_completion()
- reword some inline comments; move some comments that seemed to be
separated from the code they referred to
Signed-off-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 54 ++++++++++++++++++++++++++-----------------------
1 file changed, 29 insertions(+), 25 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 142400476d84..92eea43cfa6f 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -650,6 +650,7 @@ static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
cmd->request->next_rq->special = NULL;
}
+/* Returns false when no more bytes to process, true if there are more */
static bool scsi_end_request(struct request *req, blk_status_t error,
unsigned int bytes, unsigned int bidi_bytes)
{
@@ -772,10 +773,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
int result = cmd->result;
struct request_queue *q = cmd->device->request_queue;
struct request *req = cmd->request;
- blk_status_t error = BLK_STS_OK;
+ blk_status_t blk_stat = BLK_STS_OK; /* u8: BLK_STS_OK is only 0 */
struct scsi_sense_hdr sshdr;
bool sense_valid = false;
- int sense_deferred = 0, level = 0;
+ bool sense_current = true; /* false implies "deferred sense" */
+ int level = 0;
enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
ACTION_DELAYED_RETRY} action;
unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
@@ -783,7 +785,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
if (result) {
sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
if (sense_valid)
- sense_deferred = scsi_sense_is_deferred(&sshdr);
+ sense_current = !scsi_sense_is_deferred(&sshdr);
}
if (blk_rq_is_passthrough(req)) {
@@ -796,8 +798,9 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
min(8 + cmd->sense_buffer[7],
SCSI_SENSE_BUFFERSIZE);
}
- if (!sense_deferred)
- error = __scsi_error_from_host_byte(cmd, result);
+ if (sense_current)
+ blk_stat = __scsi_error_from_host_byte(cmd,
+ result);
}
/*
* __scsi_error_from_host_byte may have reset the host_byte
@@ -816,13 +819,13 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
BUG();
return;
}
- } else if (blk_rq_bytes(req) == 0 && result && !sense_deferred) {
+ } else if (blk_rq_bytes(req) == 0 && result && sense_current) {
/*
* Flush commands do not transfers any data, and thus cannot use
* good_bytes != blk_rq_bytes(req) as the signal for an error.
- * This sets the error explicitly for the problem case.
+ * This sets blk_stat explicitly for the problem case.
*/
- error = __scsi_error_from_host_byte(cmd, result);
+ blk_stat = __scsi_error_from_host_byte(cmd, result);
}
/* no bidi support for !blk_rq_is_passthrough yet */
@@ -852,8 +855,8 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
else if (!(req->rq_flags & RQF_QUIET))
scsi_print_sense(cmd);
result = 0;
- /* for passthrough error may be set */
- error = BLK_STS_OK;
+ /* for passthrough, blk_stat may be set */
+ blk_stat = BLK_STS_OK;
}
/*
* Another corner case: the SCSI status byte is non-zero but 'good'.
@@ -864,23 +867,24 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
*/
if (status_byte(result) && scsi_status_is_good(result)) {
result = 0;
- error = BLK_STS_OK;
+ blk_stat = BLK_STS_OK;
}
/*
- * special case: failed zero length commands always need to
- * drop down into the retry code. Otherwise, if we finished
- * all bytes in the request we are done now.
+ * Next deal with any sectors which we were able to correctly
+ * handle. Failed, zero length commands always need to drop down
+ * to retry code. Fast path should return in this block.
*/
- if (!(blk_rq_bytes(req) == 0 && error) &&
- !scsi_end_request(req, error, good_bytes, 0))
- return;
+ if (blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK) {
+ if (!scsi_end_request(req, blk_stat, good_bytes, 0))
+ return; /* no bytes remaining */
+ }
/*
* Kill remainder if no retrys.
*/
- if (error && scsi_noretry_cmd(cmd)) {
- if (scsi_end_request(req, error, blk_rq_bytes(req), 0))
+ if (blk_stat && scsi_noretry_cmd(cmd)) {
+ if (scsi_end_request(req, blk_stat, blk_rq_bytes(req), 0))
BUG();
return;
}
@@ -892,7 +896,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
if (result == 0)
goto requeue;
- error = __scsi_error_from_host_byte(cmd, result);
+ blk_stat = __scsi_error_from_host_byte(cmd, result);
if (host_byte(result) == DID_RESET) {
/* Third party bus reset or reset for error recovery
@@ -900,7 +904,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
* happens.
*/
action = ACTION_RETRY;
- } else if (sense_valid && !sense_deferred) {
+ } else if (sense_valid && sense_current) {
switch (sshdr.sense_key) {
case UNIT_ATTENTION:
if (cmd->device->removable) {
@@ -936,18 +940,18 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
action = ACTION_REPREP;
} else if (sshdr.asc == 0x10) /* DIX */ {
action = ACTION_FAIL;
- error = BLK_STS_PROTECTION;
+ blk_stat = BLK_STS_PROTECTION;
/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
} else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
action = ACTION_FAIL;
- error = BLK_STS_TARGET;
+ blk_stat = BLK_STS_TARGET;
} else
action = ACTION_FAIL;
break;
case ABORTED_COMMAND:
action = ACTION_FAIL;
if (sshdr.asc == 0x10) /* DIF */
- error = BLK_STS_PROTECTION;
+ blk_stat = BLK_STS_PROTECTION;
break;
case NOT_READY:
/* If the device is in the process of becoming
@@ -1010,7 +1014,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
scsi_print_command(cmd);
}
}
- if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0))
+ if (!scsi_end_request(req, blk_stat, blk_rq_err_bytes(req), 0))
return;
/*FALLTHRU*/
case ACTION_REPREP:
--
2.14.1
