This patch (as1144e) removes scsi_end_request(). The routine had only
one caller, so it is moved inline and simplified.
In addition, if no forward progress has been made then the patch
decrements a request's retry counter before unpreparing and requeuing
it, to avoid infinite retry loops.
Finally, fix up an omission left by an earlier change: The "error"
variable should be passed to blk_end_request().
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
CC: Jens Axboe <jens.axboe@xxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxx>
---
[Based on 2.6.30-rc2]
James, is there any reason this patch isn't getting reviewed, rejected,
or applied? Ingo has been running with it for quite a while now.
Alan Stern
Index: usb-2.6/drivers/scsi/scsi_lib.c
===================================================================
--- usb-2.6.orig/drivers/scsi/scsi_lib.c
+++ usb-2.6/drivers/scsi/scsi_lib.c
@@ -513,71 +513,6 @@ void scsi_run_host_queues(struct Scsi_Ho
static void __scsi_release_buffers(struct scsi_cmnd *, int);
-/*
- * Function: scsi_end_request()
- *
- * Purpose: Post-processing of completed commands (usually invoked at end
- * of upper level post-processing and scsi_io_completion).
- *
- * Arguments: cmd - command that is complete.
- * error - 0 if I/O indicates success, < 0 for I/O error.
- * bytes - number of bytes of completed I/O
- * requeue - indicates whether we should requeue leftovers.
- *
- * Lock status: Assumed that lock is not held upon entry.
- *
- * Returns: cmd if requeue required, NULL otherwise.
- *
- * Notes: This is called for block device requests in order to
- * mark some number of sectors as complete.
- *
- * We are guaranteeing that the request queue will be goosed
- * at some point during this call.
- * Notes: If cmd was requeued, upon return it will be a stale pointer.
- */
-static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
- int bytes, int requeue)
-{
- struct request_queue *q = cmd->device->request_queue;
- struct request *req = cmd->request;
-
- /*
- * If there are blocks left over at the end, set up the command
- * to queue the remainder of them.
- */
- if (blk_end_request(req, error, bytes)) {
- int leftover = (req->hard_nr_sectors << 9);
-
- if (blk_pc_request(req))
- leftover = req->data_len;
-
- /* kill remainder if no retrys */
- if (error && scsi_noretry_cmd(cmd))
- blk_end_request(req, error, leftover);
- else {
- if (requeue) {
- /*
- * Bleah. Leftovers again. Stick the
- * leftovers in the front of the
- * queue, and goose the queue again.
- */
- scsi_release_buffers(cmd);
- scsi_requeue_command(q, cmd);
- cmd = NULL;
- }
- return cmd;
- }
- }
-
- /*
- * This will goose the queue request function at the end, so we don't
- * need to worry about launching another command.
- */
- __scsi_release_buffers(cmd, 0);
- scsi_next_command(cmd);
- return NULL;
-}
-
static inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
@@ -739,7 +674,6 @@ static void scsi_end_bidi_request(struct
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
{
int result = cmd->result;
- int this_count;
struct request_queue *q = cmd->device->request_queue;
struct request *req = cmd->request;
int error = 0;
@@ -805,24 +739,37 @@ void scsi_io_completion(struct scsi_cmnd
error = 0;
}
- /*
- * A number of bytes were successfully read. If there
- * are leftovers and there is some kind of error
- * (result != 0), retry the rest.
- */
- if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
+ if (blk_end_request(req, error, good_bytes) == 0) {
+ /* This request is completely finished; start the next one */
+ __scsi_release_buffers(cmd, 0);
+ scsi_next_command(cmd);
return;
- this_count = blk_rq_bytes(req);
-
- error = -EIO;
+ }
- if (host_byte(result) == DID_RESET) {
+ /* The request isn't finished yet. Figure out what to do next. */
+ if (result == 0) {
+ /* No error, so carry out the remainder of the request.
+ * Failure to make forward progress counts against the
+ * the number of retries.
+ */
+ if (good_bytes > 0 || --req->retries >= 0)
+ action = ACTION_REPREP;
+ else {
+ description = "Retries exhausted";
+ action = ACTION_FAIL;
+ error = -EIO;
+ }
+ } else if (error && scsi_noretry_cmd(cmd)) {
+ /* Retrys are disallowed, so kill the remainder. */
+ action = ACTION_FAIL;
+ } else if (host_byte(result) == DID_RESET) {
/* Third party bus reset or reset for error recovery
* reasons. Just retry the command and see what
* happens.
*/
action = ACTION_RETRY;
} else if (sense_valid && !sense_deferred) {
+ error = -EIO;
switch (sshdr.sense_key) {
case UNIT_ATTENTION:
if (cmd->device->removable) {
@@ -922,7 +869,7 @@ void scsi_io_completion(struct scsi_cmnd
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
}
- blk_end_request(req, -EIO, blk_rq_bytes(req));
+ blk_end_request(req, error, blk_rq_bytes(req));
scsi_next_command(cmd);
break;
case ACTION_REPREP:
--
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