On Thu, 2007-07-26 at 00:44 -0400, dwysocha@xxxxxxxxxx wrote:
> plain text document attachment (dm-hp-sw-add-retries-handle-not-
> ready.patch)
> This patch adds retries to the hp hardware handler, and utilizes the
> MP_RETRY flag of dm-multipath. For now in the hp handler, if we get a
> pg_init completed with a check condition we just assume we can retry the
> pg_init command. We make this assumption because of incomplete data on
> specific check condition code of the HP hardware, and because testing
> has shown the HP path initialization command to be idempotent.
> The number of times we retry is settable via the "pg_init_retries"
> multipath map feature.
>
>
> Index: linux-2.6.23-rc1/drivers/md/dm-hp-sw.c
> ===================================================================
> --- linux-2.6.23-rc1.orig/drivers/md/dm-hp-sw.c
> +++ linux-2.6.23-rc1/drivers/md/dm-hp-sw.c
> @@ -18,6 +18,7 @@
> #include <linux/types.h>
> #include <scsi/scsi.h>
> #include <scsi/scsi_cmnd.h>
> +#include <scsi/scsi_dbg.h>
>
> #include "dm.h"
> #include "dm-hw-handler.h"
> @@ -26,8 +27,42 @@
>
> struct hp_sw_context {
> unsigned char sense[SCSI_SENSE_BUFFERSIZE];
> + unsigned argc;
> };
>
> +/**
> + * hp_sw_error_is_retryable - Is an HP-specific check condition retryable?
> + * @req: path activation request
> + *
> + * Examine error codes of request and determine whether the error is retryable.
> + * Some error codes are already retried by scsi-ml (see
> + * scsi_decide_disposition), but some HP specific codes are not.
> + * The intent of this routine is to supply the logic for the HP specific
> + * check conditions.
> + *
> + * Returns:
> + * 1 - command completed with retryable error
> + * 0 - command completed with non-retryable error
> + *
> + * Possible optimizations
> + * 1. More hardware-specific error codes
> + */
> +static int hp_sw_error_is_retryable(struct request *req)
> +{
> + /*
> + * NOT_READY is known to be retryable
> + * For now we just dump out the sense data and call it retryable
> + */
> + if (status_byte(req->errors) == CHECK_CONDITION)
> + __scsi_print_sense("hp_sw", req->sense, req->sense_len);
> +
> + /*
> + * At this point we don't have complete information about all the error
> + * codes from this hardware, so we are just conservative and retry
> + * when in doubt.
> + */
> + return 1;
> +}
>
> /**
> * hp_sw_end_io - Completion handler for HP path activation.
> @@ -39,8 +74,6 @@ struct hp_sw_context {
> *
> * Context: scsi-ml softirq
> *
> - * Possible optimizations
> - * 1. Actually check sense data for retryable error (e.g. NOT_READY)
> */
> static void hp_sw_end_io(struct request *req, int error)
> {
> @@ -52,11 +85,17 @@ static void hp_sw_end_io(struct request
> DMDEBUG("%s path activation command - success",
> path->dev->name);
> } else {
> - DMWARN("path activation command on %s - error=0x%x",
> - path->dev->name, error);
> + if (hp_sw_error_is_retryable(req)) {
> + DMDEBUG("%s path activation command retry",
> + path->dev->name);
mixed use of space and tabs
> + err_flags = MP_RETRY;
> + goto out;
> + }
> + DMWARN("%s path activation fail - error=0x%x",
> + path->dev->name, error);
> err_flags = MP_FAIL_PATH;
> }
> -
> + out:
space in front of label
> req->end_io_data = NULL;
> __blk_put_request(req->q, req);
> dm_pg_init_complete(path, err_flags);
> @@ -134,17 +173,16 @@ static void hp_sw_pg_init(struct hw_hand
> if (!req) {
> DMERR("%s path activation command allocation fail ",
> path->dev->name);
> - goto fail;
> + goto retry;
> }
>
> - DMDEBUG("path activation command sent on %s",
> - path->dev->name);
> + DMDEBUG("%s path activation command sent", path->dev->name);
>
> blk_execute_rq_nowait(req->q, NULL, req, 1, hp_sw_end_io);
> return;
>
> - fail:
> - dm_pg_init_complete(path, MP_FAIL_PATH);
> + retry:
> + dm_pg_init_complete(path, MP_RETRY);
> }
>
> static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv)
> @@ -181,7 +219,7 @@ static int __init hp_sw_init(void)
> if (r < 0)
> DMERR("register failed %d", r);
> else
> - DMINFO("version 0.0.2 loaded");
> + DMINFO("version 0.0.3 loaded");
>
> return r;
> }
>
--
----------------------------------------------------------------------
Chandra Seetharaman | Be careful what you choose....
- sekharan@xxxxxxxxxx | .......you may get it.
----------------------------------------------------------------------
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