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scsi: remove scsi_end_request

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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>
This commit is contained in:
Christoph Hellwig 2014-05-01 16:51:03 +02:00
parent c682adf3e1
commit bc85dc500f
1 changed files with 32 additions and 82 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

114
drivers/scsi/scsi_lib.c
View file

@ -512,66 +512,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
scsi_run_queue(sdev->request_queue);
}
/*
* 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);
scsi_next_command(cmd);
return NULL;
}
static inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
@ -717,16 +657,9 @@ 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
@ -735,7 +668,7 @@ 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.
*
@ -794,6 +727,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
scsi_release_buffers(cmd);
scsi_release_bidi_buffers(cmd);
blk_end_request_all(req, 0);
scsi_next_command(cmd);
@ -833,12 +767,25 @@ 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);
@ -966,7 +913,6 @@ 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",
@ -976,12 +922,11 @@ 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.
*/
@ -997,6 +942,11 @@ 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,