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scsi: remove scsi_end_request
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. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org> Reviewed-by: Mike Christie <michaelc@cs.wisc.edu> Reviewed-by: Hannes Reinecke <hare@suse.de>
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1 changed files with 32 additions and 82 deletions
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@ -512,66 +512,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
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scsi_run_queue(sdev->request_queue);
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}
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/*
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* Function: scsi_end_request()
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*
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* Purpose: Post-processing of completed commands (usually invoked at end
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* of upper level post-processing and scsi_io_completion).
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*
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* Arguments: cmd - command that is complete.
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* error - 0 if I/O indicates success, < 0 for I/O error.
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* bytes - number of bytes of completed I/O
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* requeue - indicates whether we should requeue leftovers.
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*
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* Lock status: Assumed that lock is not held upon entry.
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*
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* Returns: cmd if requeue required, NULL otherwise.
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*
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* Notes: This is called for block device requests in order to
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* mark some number of sectors as complete.
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*
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* We are guaranteeing that the request queue will be goosed
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* at some point during this call.
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* Notes: If cmd was requeued, upon return it will be a stale pointer.
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*/
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static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
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int bytes, int requeue)
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{
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struct request_queue *q = cmd->device->request_queue;
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struct request *req = cmd->request;
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/*
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* If there are blocks left over at the end, set up the command
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* to queue the remainder of them.
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*/
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if (blk_end_request(req, error, bytes)) {
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/* kill remainder if no retrys */
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if (error && scsi_noretry_cmd(cmd))
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blk_end_request_all(req, error);
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else {
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if (requeue) {
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/*
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* Bleah. Leftovers again. Stick the
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* leftovers in the front of the
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* queue, and goose the queue again.
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*/
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scsi_release_buffers(cmd);
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scsi_requeue_command(q, cmd);
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cmd = NULL;
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}
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return cmd;
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}
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}
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/*
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* This will goose the queue request function at the end, so we don't
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* need to worry about launching another command.
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*/
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scsi_release_buffers(cmd);
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scsi_next_command(cmd);
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return NULL;
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}
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static inline unsigned int scsi_sgtable_index(unsigned short nents)
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{
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unsigned int index;
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@ -717,16 +657,9 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
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*
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* Returns: Nothing
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*
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* Notes: This function is matched in terms of capabilities to
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* the function that created the scatter-gather list.
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* In other words, if there are no bounce buffers
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* (the normal case for most drivers), we don't need
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* the logic to deal with cleaning up afterwards.
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*
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* We must call scsi_end_request(). This will finish off
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* the specified number of sectors. If we are done, the
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* command block will be released and the queue function
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* will be goosed. If we are not done then we have to
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* Notes: We will finish off the specified number of sectors. If we
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* are done, the command block will be released and the queue
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* function will be goosed. If we are not done then we have to
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* figure out what to do next:
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*
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* a) We can call scsi_requeue_command(). The request
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@ -735,7 +668,7 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
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* be used if we made forward progress, or if we want
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* to switch from READ(10) to READ(6) for example.
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*
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* b) We can call scsi_queue_insert(). The request will
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* b) We can call __scsi_queue_insert(). The request will
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* be put back on the queue and retried using the same
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* command as before, possibly after a delay.
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*
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@ -794,6 +727,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
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scsi_release_buffers(cmd);
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scsi_release_bidi_buffers(cmd);
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blk_end_request_all(req, 0);
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scsi_next_command(cmd);
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@ -833,12 +767,25 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
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}
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/*
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* A number of bytes were successfully read. If there
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* are leftovers and there is some kind of error
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* (result != 0), retry the rest.
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* If we finished all bytes in the request we are done now.
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*/
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if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
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return;
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if (!blk_end_request(req, error, good_bytes))
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goto next_command;
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/*
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* Kill remainder if no retrys.
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*/
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if (error && scsi_noretry_cmd(cmd)) {
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blk_end_request_all(req, error);
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goto next_command;
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}
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/*
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* If there had been no error, but we have leftover bytes in the
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* requeues just queue the command up again.
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*/
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if (result == 0)
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goto requeue;
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error = __scsi_error_from_host_byte(cmd, result);
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@ -966,7 +913,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
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switch (action) {
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case ACTION_FAIL:
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/* Give up and fail the remainder of the request */
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scsi_release_buffers(cmd);
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if (!(req->cmd_flags & REQ_QUIET)) {
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if (description)
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scmd_printk(KERN_INFO, cmd, "%s\n",
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@ -976,12 +922,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
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scsi_print_sense("", cmd);
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scsi_print_command(cmd);
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}
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if (blk_end_request_err(req, error))
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scsi_requeue_command(q, cmd);
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else
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scsi_next_command(cmd);
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break;
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if (!blk_end_request_err(req, error))
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goto next_command;
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/*FALLTHRU*/
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case ACTION_REPREP:
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requeue:
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/* Unprep the request and put it back at the head of the queue.
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* A new command will be prepared and issued.
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*/
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@ -997,6 +942,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
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__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
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break;
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}
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return;
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next_command:
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scsi_release_buffers(cmd);
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scsi_next_command(cmd);
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}
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static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
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