Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754471Ab3HWDVR (ORCPT ); Thu, 22 Aug 2013 23:21:17 -0400 Received: from TYO200.gate.nec.co.jp ([210.143.35.50]:57798 "EHLO tyo200.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754409Ab3HWDVP (ORCPT ); Thu, 22 Aug 2013 23:21:15 -0400 X-Greylist: delayed 362 seconds by postgrey-1.27 at vger.kernel.org; Thu, 22 Aug 2013 23:21:15 EDT Message-ID: <5216D3A2.8020209@ce.jp.nec.com> Date: Fri, 23 Aug 2013 12:14:42 +0900 From: "Jun'ichi Nomura" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 MIME-Version: 1.0 To: device-mapper development , Mike Snitzer CC: Joe Jin , Mikulas Patocka , "linux-kernel@vger.kernel.org" , Alasdair Kergon Subject: Re: [dm-devel] [PATCH] dm: allow error target to replace either bio-based and request-based targets References: <5214CC25.1070307@oracle.com> <52157C6E.6080406@oracle.com> <20130822201900.GB22556@redhat.com> <20130823001750.GA29366@redhat.com> In-Reply-To: <20130823001750.GA29366@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4404 Lines: 140 Hello Mike, On 08/23/13 09:17, Mike Snitzer wrote: >> I do like the idea of a single error target that is hybrid (supports >> both bio-based and request-based) but the DM core would need to be >> updated to support this. >> >> Specifically, we'd need to check if the device (and active table) is >> already bio-based or request-based and select the appropriate type. If >> it is a new device, default to selecting bio-based. >> >> There are some wrappers and other logic thoughout DM core that will need >> auditing too. > > Here is a patch that should work for your needs (I tested it to work > with 'dmsetup wipe_table' on both request-based and bio-based devices): How about moving the default handling in dm_table_set_type() outside of the for-each-target loop, like the modified patch below? For example, if a table has 2 targets, hybrid and request_based, and live_md_type is DM_TYPE_NONE, the table should be considered as request_based, not inconsistent. Though the end result is same as such a table is rejected by other constraint anyway, I think it's good to keep the semantics clean and error messages consistent. I.e. for the above case, the error message should be "Request-based dm doesn't support multiple targets yet", not "Inconsistent table: different target types can't be mixed up". --- Jun'ichi Nomura, NEC Corporation diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f221812..6e683c8 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -860,14 +860,16 @@ EXPORT_SYMBOL(dm_consume_args); static int dm_table_set_type(struct dm_table *t) { unsigned i; - unsigned bio_based = 0, request_based = 0; + unsigned bio_based = 0, request_based = 0, hybrid = 0; struct dm_target *tgt; struct dm_dev_internal *dd; struct list_head *devices; for (i = 0; i < t->num_targets; i++) { tgt = t->targets + i; - if (dm_target_request_based(tgt)) + if (dm_target_hybrid(tgt)) + hybrid = 1; + else if (dm_target_request_based(tgt)) request_based = 1; else bio_based = 1; @@ -879,6 +881,25 @@ static int dm_table_set_type(struct dm_table *t) } } + if (hybrid && !bio_based && !request_based) { + /* + * The targets can work either way. + * Determine the type from the live device. + */ + unsigned live_md_type; + dm_lock_md_type(t->md); + live_md_type = dm_get_md_type(t->md); + dm_unlock_md_type(t->md); + switch (live_md_type) { + case DM_TYPE_REQUEST_BASED: + request_based = 1; + break; + default: + bio_based = 1; + break; + } + } + if (bio_based) { /* We must use this table as bio-based */ t->type = DM_TYPE_BIO_BASED; diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c index 37ba5db..242e3ce 100644 --- a/drivers/md/dm-target.c +++ b/drivers/md/dm-target.c @@ -131,12 +131,19 @@ static int io_err_map(struct dm_target *tt, struct bio *bio) return -EIO; } +static int io_err_map_rq(struct dm_target *ti, struct request *clone, + union map_info *map_context) +{ + return -EIO; +} + static struct target_type error_target = { .name = "error", - .version = {1, 1, 0}, + .version = {1, 2, 0}, .ctr = io_err_ctr, .dtr = io_err_dtr, .map = io_err_map, + .map_rq = io_err_map_rq, }; int __init dm_target_init(void) diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 45b97da..8b4c075 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -89,10 +89,21 @@ int dm_setup_md_queue(struct mapped_device *md); #define dm_target_is_valid(t) ((t)->table) /* + * To check whether the target type is bio-based or not (request-based). + */ +#define dm_target_bio_based(t) ((t)->type->map != NULL) + +/* * To check whether the target type is request-based or not (bio-based). */ #define dm_target_request_based(t) ((t)->type->map_rq != NULL) +/* + * To check whether the target type is a hybrid (capable of being + * either request-based or bio-based). + */ +#define dm_target_hybrid(t) (dm_target_bio_based(t) && dm_target_request_based(t)) + /*----------------------------------------------------------------- * A registry of target types. *---------------------------------------------------------------*/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/