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Re: [dm-devel] [patch 1/3] Extremely basic hp hardware handler (no retries, no error handling, etc).



Do you want to keep the DMDEBUG in this patch ?

Other than that it looks good...

Thanks

chandra
On Mon, 2007-07-30 at 14:06 -0400, Dave Wysochanski wrote:
> On Thu, 2007-07-26 at 12:09 -0700, Chandra Seetharaman wrote:
> > Hi Dave,
> > 
> > some coding style related comments (below).
> > 
> > On Thu, 2007-07-26 at 00:44 -0400, dwysocha redhat com wrote:
> > > plain text document attachment (dm-hp-sw-v0.0.2.patch)
> > > This patch adds the most basic dm-multipath hardware support for the 
> > > HP active/passive arrays.
> > > 
> > > 
> > > Index: linux-2.6.23-rc1/drivers/md/Makefile
> > > ===================================================================
> > > --- linux-2.6.23-rc1.orig/drivers/md/Makefile
> > > +++ linux-2.6.23-rc1/drivers/md/Makefile
> > > @@ -35,6 +35,7 @@ obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
> > >  obj-$(CONFIG_DM_DELAY)		+= dm-delay.o
> > >  obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o
> > >  obj-$(CONFIG_DM_MULTIPATH_EMC)	+= dm-emc.o
> > > +obj-$(CONFIG_DM_MULTIPATH_HP)	+= dm-hp-sw.o
> > >  obj-$(CONFIG_DM_MULTIPATH_RDAC)	+= dm-rdac.o
> > >  obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
> > >  obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o
> > > Index: linux-2.6.23-rc1/drivers/md/dm-hp-sw.c
> > > ===================================================================
> > > --- /dev/null
> > > +++ linux-2.6.23-rc1/drivers/md/dm-hp-sw.c
> > > @@ -0,0 +1,203 @@
> > > +/*
> > > + * Copyright (C) 2005 Mike Christie, All rights reserved.
> > > + * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
> > > + * Authors: Mike Christie
> > > + *          Dave Wysochanski
> > > + *
> > > + * This file is released under the GPL.
> > > + *
> > > + * This module implements the specific path activation code for
> > > + * HP StorageWorks and FSC FibreCat Asymmetric (Active/Passive)
> > > + * storage arrays.
> > > + * These storage arrays have controller-based failover, not
> > > + * LUN-based failover.  However, LUN-based failover is the design
> > > + * of dm-multipath. Thus, this module is written for LUN-based failover.
> > > + */
> > > +#include <linux/blkdev.h>
> > > +#include <linux/list.h>
> > > +#include <linux/types.h>
> > > +#include <scsi/scsi.h>
> > > +#include <scsi/scsi_cmnd.h>
> > > +
> > > +#include "dm.h"
> > > +#include "dm-hw-handler.h"
> > > +
> > > +#define DM_MSG_PREFIX "multipath hp_sw"
> > > +
> > > +struct hp_sw_context {
> > > +	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
> > > +};
> > > +
> > > +
> > > +/**
> > > + * hp_sw_end_io - Completion handler for HP path activation.
> > > + * @req: path activation request
> > > + * @error: scsi-ml error
> > > + *
> > > + *  Check sense data, free request structure, and notify dm that
> > > + *  pg initialization has completed.
> > > + *
> > > + * 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)
> > > +{
> > > +	struct dm_path *path = req->end_io_data;
> > > +	unsigned err_flags;
> > > +
> > > +	if (!error) {
> > > +		err_flags = 0;
> > > +		DMDEBUG("%s path activation command - success",
> > > +		       	path->dev->name);
> > 
> > Mixed use of space and tab for indentation (many other places too).
> > 
> > > +	} else {
> > > +		DMWARN("path activation command on %s - error=0x%x",
> > 
> > Could use the same format like "%s: path activation command - status",
> > you made changes towards that in the next patch. Could make is
> > consistent.
> > 
> > > +		       path->dev->name, error);
> > > +		err_flags = MP_FAIL_PATH;
> > > +	}
> > > +
> > > +	req->end_io_data = NULL;
> > > +	__blk_put_request(req->q, req);
> > > +	dm_pg_init_complete(path, err_flags);
> > > +}
> > > +
> > > +/**
> > > + * hp_sw_get_request - Allocate an HP specific path activation request
> > > + * @path: path on which request will be sent (needed for request queue)
> > > + *
> > > + * The START command is used for path activation request.
> > > + * These arrays are controller-based failover, not LUN based.
> > > + * One START command issued to a single path will fail over all
> > > + * LUNs for the same controller.
> > > + *
> > > + * Possible optimizations
> > > + * 1. Make timeout configurable
> > > + * 2. Preallocate request
> > > + */
> > > +static struct request *hp_sw_get_request(struct dm_path *path)
> > > +{
> > > +	struct request *req;
> > > +	struct block_device *bdev = path->dev->bdev;
> > > +	struct request_queue *q = bdev_get_queue(bdev);
> > > +	struct hp_sw_context *h = path->hwhcontext;
> > > +
> > > +	req = blk_get_request(q, WRITE, GFP_NOIO);
> > > +	if (!req)
> > > +		goto out;
> > > +
> > > +	req->timeout = 60*HZ;
> > > +
> > > +	req->errors = 0;
> > > +	req->cmd_type = REQ_TYPE_BLOCK_PC;
> > > +	req->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
> > > +	req->end_io_data = path;
> > > +	req->sense = h->sense;
> > > +	memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE);
> > > +
> > > +	memset(&req->cmd, 0, BLK_MAX_CDB);
> > > +	req->cmd[0] = START_STOP;
> > > +	req->cmd[4] = 1;
> > > +	req->cmd_len = COMMAND_SIZE(req->cmd[0]);
> > > + out:
> > 
> > I think there will be no space before the label (one more below).
> > 
> > > +	return req;
> > > +}
> > > +
> > > +/**
> > > + * hp_sw_pg_init - HP path activation implementation.
> > > + * @hwh: hardware handler specific data
> > > + * @bypassed: unused; is the path group bypassed? (see dm-mpath.c)
> > > + * @path: path to send initialization command
> > > + *
> > > + * Send an HP-specific path activation command on 'path'.
> > > + * Do not try to optimize in any way, just send the activation command.
> > > + * More than one path activation command may be sent to the same controller.
> > > + * This seems to work fine for basic failover support.
> > > + *
> > > + * Possible optimizations
> > > + * 1. Detect an in-progress activation request and avoid submitting another one
> > > + * 2. Model the controller and only send a single activation request at a time
> > > + * 3. Determine the state of a path before sending an activation request
> > > + *
> > > + * Context: kmpathd (see process_queued_ios() in dm-mpath.c)
> > > + */
> > > +static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed,
> > > +			  struct dm_path *path)
> > > +{
> > > +	struct request *req;
> > > +	struct hp_sw_context *h;
> > > +
> > > +	path->hwhcontext = hwh->context;
> > > +	h = hwh->context;
> > > +
> > > +	req = hp_sw_get_request(path);
> > > +	if (!req) {
> > > +		DMERR("%s path activation command allocation fail ",
> > > +		      path->dev->name);
> > > +		goto fail;
> > > +	}
> > > +
> > > +	DMDEBUG("path activation command sent on %s",
> > > +		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);
> > > +}
> > > +
> > > +static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv)
> > > +{
> > > +	struct hp_sw_context *h;
> > > +
> > > +	h = kmalloc(sizeof(*h), GFP_KERNEL);
> > > +	if (!h)
> > > +		return -ENOMEM;
> > > +	hwh->context = h;
> > > +	return 0;
> > > +}
> > > +
> > > +static void hp_sw_destroy(struct hw_handler *hwh)
> > > +{
> > > +	struct hp_sw_context *h = hwh->context;
> > > +
> > > +	kfree(h);
> > > +}
> > > +
> > > +static struct hw_handler_type hp_sw_hwh = {
> > > +	.name = "hp_sw",
> > > +	.module = THIS_MODULE,
> > > +	.create = hp_sw_create,
> > > +	.destroy = hp_sw_destroy,
> > > +	.pg_init = hp_sw_pg_init,
> > > +};
> > > +
> > > +static int __init hp_sw_init(void)
> > > +{
> > > +	int r;
> > > +
> > > +	r = dm_register_hw_handler(&hp_sw_hwh);
> > > +	if (r < 0)
> > > +		DMERR("register failed %d", r);
> > > +	else
> > > +		DMINFO("version 0.0.2 loaded");
> > > +
> > > +	return r;
> > > +}
> > > +
> > > +static void __exit hp_sw_exit(void)
> > > +{
> > > +	int r;
> > > +
> > > +	r = dm_unregister_hw_handler(&hp_sw_hwh);
> > > +	if (r < 0)
> > > +		DMERR("unregister failed %d", r);
> > > +}
> > > +
> > > +module_init(hp_sw_init);
> > > +module_exit(hp_sw_exit);
> > > +
> > > +MODULE_DESCRIPTION("HP StorageWorks and FSC FibreCat (A/P) support for dm-multipath");
> > > +MODULE_AUTHOR("Mike Christie <michaelc cs wisc edu>");
> > > +MODULE_LICENSE("GPL");
> > > Index: linux-2.6.23-rc1/drivers/md/Kconfig
> > > ===================================================================
> > > --- linux-2.6.23-rc1.orig/drivers/md/Kconfig
> > > +++ linux-2.6.23-rc1/drivers/md/Kconfig
> > > @@ -267,6 +267,12 @@ config DM_MULTIPATH_RDAC
> > >  	---help---
> > >  	  Multipath support for LSI/Engenio RDAC.
> > > 
> > > +config DM_MULTIPATH_HP
> > > +        tristate "HP MSA multipath support (EXPERIMENTAL)"
> > > +        depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
> > > +        ---help---
> > > +          Multipath support for HP MSA (Active/Passive) series hardware.
> > > +
> > >  config DM_DELAY
> > >  	tristate "I/O delaying target (EXPERIMENTAL)"
> > >  	depends on BLK_DEV_DM && EXPERIMENTAL
> > > 
> > -- 
> > 
> 
> I think the attached patch addresses all of your comments.
> 
> 
-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan us ibm com   |      .......you may get it.
----------------------------------------------------------------------



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