Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754602Ab3HWARz (ORCPT ); Thu, 22 Aug 2013 20:17:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36891 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753629Ab3HWARy (ORCPT ); Thu, 22 Aug 2013 20:17:54 -0400 Date: Thu, 22 Aug 2013 20:17:51 -0400 From: Mike Snitzer To: Joe Jin Cc: Mikulas Patocka , device-mapper development , Alasdair Kergon , "linux-kernel@vger.kernel.org" Subject: [PATCH] dm: allow error target to replace either bio-based and request-based targets Message-ID: <20130823001750.GA29366@redhat.com> References: <5214CC25.1070307@oracle.com> <52157C6E.6080406@oracle.com> <20130822201900.GB22556@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130822201900.GB22556@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4369 Lines: 132 On Thu, Aug 22 2013 at 4:19pm -0400, Mike Snitzer wrote: > Hi Joe, > > Unfortunately this isn't going to work properly. Mikulas suggested a > new "error-rq" target. > > 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): From: Mike Snitzer Date: Thu, 22 Aug 2013 18:21:38 -0400 Subject: [PATCH] dm: allow error target to replace either bio-based and request-based targets In may be useful to switch a request-based table to the "error" target. Enhance the DM core to allow a single hybrid target to be capable of handling either bios or requests. Add a request-based (.map_rq) member to the error target_type and train dm_table_set_type() to prefer the md's established type (request-based or bio-based). If the md doesn't have an established type default to making the hybrid target bio-based. Cc: Joe Jin Cc: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-table.c | 18 +++++++++++++++++- drivers/md/dm-target.c | 9 ++++++++- drivers/md/dm.h | 11 +++++++++++ 3 files changed, 36 insertions(+), 2 deletions(-) Index: linux/drivers/md/dm-table.c =================================================================== --- linux.orig/drivers/md/dm-table.c +++ linux/drivers/md/dm-table.c @@ -864,10 +864,26 @@ static int dm_table_set_type(struct dm_t struct dm_target *tgt; struct dm_dev_internal *dd; struct list_head *devices; + 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); for (i = 0; i < t->num_targets; i++) { tgt = t->targets + i; - if (dm_target_request_based(tgt)) + if (dm_target_hybrid(tgt)) { + switch (live_md_type) { + case DM_TYPE_NONE: + case DM_TYPE_BIO_BASED: + bio_based = 1; + break; + case DM_TYPE_REQUEST_BASED: + request_based = 1; + break; + } + } + else if (dm_target_request_based(tgt)) request_based = 1; else bio_based = 1; Index: linux/drivers/md/dm-target.c =================================================================== --- linux.orig/drivers/md/dm-target.c +++ linux/drivers/md/dm-target.c @@ -131,12 +131,19 @@ static int io_err_map(struct dm_target * 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) Index: linux/drivers/md/dm.h =================================================================== --- linux.orig/drivers/md/dm.h +++ linux/drivers/md/dm.h @@ -91,10 +91,21 @@ int dm_setup_md_queue(struct mapped_devi #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/