From 169e2cc279c443085f7e423561eb1fe6158ade44 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 22 Aug 2013 18:21:38 -0400 Subject: dm: allow error target to replace bio-based and request-based targets It may be useful to switch a request-based table to the "error" target. Enhance the DM core to allow a hybrid target_type which is capable of handling either bios (via .map) or requests (via .map_rq). Add a request-based map function (.map_rq) to the "error" target_type; making it DM's first hybrid target. Train dm_table_set_type() to prefer the mapped device's established type (request-based or bio-based). If the mapped device doesn't have an established type default to making the table with the hybrid target(s) bio-based. Tested 'dmsetup wipe_table' to work on both bio-based and request-based devices. Signed-off-by: Mike Snitzer Signed-off-by: Joe Jin Signed-off-by: Jun'ichi Nomura Acked-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 22 ++++++++++++++++++++-- drivers/md/dm-target.c | 9 ++++++++- drivers/md/dm.h | 11 +++++++++++ 3 files changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f221812b7dbc..f309477d7efe 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -860,14 +860,17 @@ 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; + unsigned live_md_type; 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 +882,21 @@ 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. + * Default to bio-based if device is new. + */ + dm_lock_md_type(t->md); + live_md_type = dm_get_md_type(t->md); + dm_unlock_md_type(t->md); + if (live_md_type == DM_TYPE_REQUEST_BASED) + request_based = 1; + else + bio_based = 1; + } + 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 37ba5db71cd9..242e3cec397a 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 45b97da1bd06..8b4c075d9a2f 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -88,11 +88,22 @@ 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. *---------------------------------------------------------------*/ -- cgit v1.2.3