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Message-Id: <20070711144303.9400acba.akpm@linux-foundation.org>
Date: Wed, 11 Jul 2007 14:43:03 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Alasdair G Kergon <agk@...hat.com>
Cc: dm-devel@...hat.com, linux-kernel@...r.kernel.org,
Mike Christie <michaelc@...wisc.edu>
Subject: Re: [2.6.23 PATCH 16/18] dm mpath: rdac
On Wed, 11 Jul 2007 22:02:42 +0100
Alasdair G Kergon <agk@...hat.com> wrote:
> From: Mike Christie <michaelc@...wisc.edu>
>
> This patch from Chandra Seetharaman and updated to upstream by me,
> supports LSI/Engenio devices in RDAC mode. Like dm-emc
> it requires userspace support. In your multipath.conf file you must have:
>
> path_checker rdac
> hardware_handler "1 rdac"
>
> And you also then must have a updated multipath tools release which
> has rdac support.
>
> ...
>
> +static spinlock_t list_lock = SPIN_LOCK_UNLOCKED;
This defeats lockdep. Please use DEFINE_SPINLOCK.
> +#define submit_c9_inquiry(h) \
> + submit_inquiry(h, 0xC9, sizeof(struct c9_inquiry), c9_inquiry_endio)
> +#define submit_c4_inquiry(h) \
> + submit_inquiry(h, 0xC4, sizeof(struct c4_inquiry), c4_inquiry_endio)
> +#define submit_c8_inquiry(h) \
> + submit_inquiry(h, 0xC8, sizeof(struct c8_inquiry), c8_inquiry_endio)
> +#define submit_c2_inquiry(h) \
> + submit_inquiry(h, 0xC2, sizeof(struct c2_inquiry), c2_inquiry_endio)
These don't have to be implemented as macros.
> +static struct request *get_rdac_req(struct rdac_handler *h,
> + void *buffer, unsigned buflen, int rw)
> +{
> + struct request *rq;
> + struct request_queue *q = bdev_get_queue(h->path->dev->bdev);
> +
> + rq = blk_get_request(q, rw, GFP_ATOMIC);
GFP_ATOMIC is unreliable. Is it really unavoidable?
> + if (!rq) {
> + DMINFO("get_rdac_req: blk_get_request failed");
> + return NULL;
> + }
> +
> + if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_ATOMIC)) {
> + blk_put_request(rq);
> + DMINFO("get_rdac_req: blk_rq_map_kern failed");
> + return NULL;
> + }
> +
> + memset(&rq->cmd, 0, BLK_MAX_CDB);
> + rq->sense = h->sense;
> + memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
> + rq->sense_len = 0;
> +
> + rq->end_io_data = h;
> + rq->timeout = h->timeout;
> + rq->cmd_type = REQ_TYPE_BLOCK_PC;
> + rq->cmd_flags = REQ_FAILFAST | REQ_NOMERGE;
> + return rq;
> +}
> +
>
> ...
>
> +
> +/* Acquires h->ctlr->lock */
> +static void submit_mode_select(struct rdac_handler *h)
> +{
> + struct request *rq;
> + struct request_queue *q = bdev_get_queue(h->path->dev->bdev);
> +
> + spin_lock(&h->ctlr->lock);
> + if (h->ctlr->submitted) {
> + list_add(&h->entry, &h->ctlr->cmd_list);
> + goto drop_lock;
> + }
> +
> + if (!q) {
> + DMINFO("submit_mode_select: no queue");
> + goto fail_path;
> + }
> +
> + rq = rdac_failover_get(h);
> + if (!rq) {
> + DMERR("submit_mode_select: no rq");
> + goto fail_path;
> + }
> +
> + DMINFO("queueing MODE_SELECT command on %s", h->path->dev->name);
> +
> + blk_execute_rq_nowait(q, NULL, rq, 1, mode_select_endio);
I suspect we could call this after dropping the lock?
> + h->ctlr->submitted = 1;
> + goto drop_lock;
> +fail_path:
> + dm_pg_init_complete(h->path, MP_FAIL_PATH);
> +drop_lock:
> + spin_unlock(&h->ctlr->lock);
> +}
> +
>
> ...
>
> +static void c2_inquiry_endio(struct request *req, int error)
> +{
> + struct rdac_handler *h = req->end_io_data;
> + struct c2_inquiry *sp;
> +
> + if (had_failures(req, error)) {
> + dm_pg_init_complete(h->path, MP_FAIL_PATH);
> + goto done;
> + }
> +
> + sp = (struct c2_inquiry *)&h->inq;
That's funny-looking and un-typesafe. Why not do
sp = &h->inq.c2;
?
(Dittoes in various other places..)
> +
> + /* If more than MODE6_MAX_LUN luns are supported, use mode select 10 */
> + if (sp->max_lun_supported >= MODE6_MAX_LUN)
> + h->ctlr->use_10_ms = 1;
> + else
> + h->ctlr->use_10_ms = 0;
> +
> + h->cmd_to_send = SEND_MODE_SELECT;
> + queue_work(rdac_wkqd, &h->work);
> +done:
> + __blk_put_request(req->q, req);
> +}
> +
> +static void rdac_destroy(struct hw_handler *hwh)
> +{
> + struct rdac_handler *h = (struct rdac_handler *) hwh->context;
Unneeded (and undesirable) cast of void*. Please check the whole
patch(set) for this.
> + if (h->ctlr)
> + kref_put(&h->ctlr->kref, release_ctlr);
> + kfree(h);
> + hwh->context = NULL;
> +}
> +
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