By folding scsi_end_request into its only caller we can significantly clean up the completion logic. We can use simple goto labels now to only have a single place to finish or requeue command there instead of the previous convoluted logic.
Note that the switch from __scsi_release_buffers without the bidi check argument to scsi_release_buffers is always correct as we handle bidi commands separately in scsi_io_completion and they never reach the path scsi_end_request was called from. Signed-off-by: Christoph Hellwig <h...@lst.de> --- drivers/scsi/scsi_lib.c | 119 +++++++++++++---------------------------------- 1 file changed, 32 insertions(+), 87 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 62ec84b..51063ca 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -540,66 +540,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost) 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)) { - /* kill remainder if no retrys */ - if (error && scsi_noretry_cmd(cmd)) - blk_end_request_all(req, error); - 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; @@ -751,16 +691,9 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result) * * Returns: Nothing * - * Notes: This function is matched in terms of capabilities to - * the function that created the scatter-gather list. - * In other words, if there are no bounce buffers - * (the normal case for most drivers), we don't need - * the logic to deal with cleaning up afterwards. - * - * We must call scsi_end_request(). This will finish off - * the specified number of sectors. If we are done, the - * command block will be released and the queue function - * will be goosed. If we are not done then we have to + * Notes: We will finish off the specified number of sectors. If we + * are done, the command block will be released and the queue + * function will be goosed. If we are not done then we have to * figure out what to do next: * * a) We can call scsi_requeue_command(). The request @@ -769,7 +702,7 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result) * be used if we made forward progress, or if we want * to switch from READ(10) to READ(6) for example. * - * b) We can call scsi_queue_insert(). The request will + * b) We can call __scsi_queue_insert(). The request will * be put back on the queue and retried using the same * command as before, possibly after a delay. * @@ -824,12 +757,8 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) * both sides at once. */ req->next_rq->resid_len = scsi_in(cmd)->resid; - - scsi_release_buffers(cmd); blk_end_request_all(req, 0); - - scsi_next_command(cmd); - return; + goto next_command; } } @@ -865,12 +794,25 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) } /* - * A number of bytes were successfully read. If there - * are leftovers and there is some kind of error - * (result != 0), retry the rest. + * If we finished all bytes in the request we are done now. */ - if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL) - return; + if (!blk_end_request(req, error, good_bytes)) + goto next_command; + + /* + * Kill remainder if no retrys. + */ + if (error && scsi_noretry_cmd(cmd)) { + blk_end_request_all(req, error); + goto next_command; + } + + /* + * If there had been no error, but we have leftover bytes in the + * requeues just queue the command up again. + */ + if (result == 0) + goto requeue; error = __scsi_error_from_host_byte(cmd, result); @@ -992,7 +934,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) switch (action) { case ACTION_FAIL: /* Give up and fail the remainder of the request */ - scsi_release_buffers(cmd); if (!(req->cmd_flags & REQ_QUIET)) { if (description) scmd_printk(KERN_INFO, cmd, "%s\n", @@ -1002,12 +943,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) scsi_print_sense("", cmd); scsi_print_command(cmd); } - if (blk_end_request_err(req, error)) - scsi_requeue_command(q, cmd); - else - scsi_next_command(cmd); - break; + if (!blk_end_request_err(req, error)) + goto next_command; + /*FALLTHRU*/ case ACTION_REPREP: + requeue: /* Unprep the request and put it back at the head of the queue. * A new command will be prepared and issued. */ @@ -1023,6 +963,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0); break; } + return; + +next_command: + scsi_release_buffers(cmd); + scsi_next_command(cmd); } static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html