linux-kernel - Re: [PATCH 2/2 v2] UBI: Block: Add blk-mq support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <54B5A188.2000001@nod.at>
Date:	Tue, 13 Jan 2015 23:51:52 +0100
From:	Richard Weinberger <richard@....at>
To:	Christoph Hellwig <hch@...radead.org>
CC:	dedekind1@...il.com, dwmw2@...radead.org,
	computersforpeace@...il.com, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org, axboe@...com, tom.leiming@...il.com
Subject: Re: [PATCH 2/2 v2] UBI: Block: Add blk-mq support

Am 13.01.2015 um 17:25 schrieb Christoph Hellwig:
>> +	struct ubi_sgl usgl;
> 
> Btw, what's in struct ubi_sgl?  Can't find that in my tree.

"[PATCH 1/2] UBI: Add initial support for scatter gather" adds it.

/**
 * struct ubi_sgl - UBI scatter gather list data structure.
 * @list_pos: current position in @sg[]
 * @page_pos: current position in @sg[@list_pos]
 * @sg: the scatter gather list itself
 *
 * ubi_sgl is a wrapper around a scatter list which keeps track of the
 * current position in the list and the current list item such that
 * it can be used across multiple ubi_leb_read_sg() calls.
 */
struct ubi_sgl {
        int list_pos;
        int page_pos;
        struct scatterlist sg[UBI_MAX_SG_COUNT];
};

>> +static void ubiblock_do_work(struct work_struct *work)
>> +{
>> +	int ret;
>> +	struct ubiblock_pdu *pdu = container_of(work, struct ubiblock_pdu, work);
>> +	struct request *req = blk_mq_rq_from_pdu(pdu);
>> +
>> +	blk_mq_start_request(req);
>> +	blk_rq_map_sg(req->q, req, pdu->usgl.sg);
> 
> blk_rq_map_sg returns the number of entries actually mapped, which
> might be smaller than the number passed in due to merging.

Yep, but the ubi_sql has a fixed number of scatterlist entries, UBI_MAX_SG_COUNT.
And I limit it also to that using: blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);

Is there another reason why I should use the return value of blk_rq_map_sg()?
Please also note that the UBI block driver is read-only.

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/