From 10d3bd09a3c25df114f74f7f86e1b58d070bef32 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Tue, 6 Jan 2009 03:04:58 +0000 Subject: dm: consolidate target deregistration error handling Change dm_unregister_target to return void and use BUG() for error reporting. dm_unregister_target can only fail because of programming bug in the target driver. It can't fail because of user's behavior or disk errors. This patch changes unregister_target to return void and use BUG if someone tries to unregister non-registered target or unregister target that is in use. This patch removes code duplication (testing of error codes in all dm targets) and reports bugs in just one place, in dm_unregister_target. In some target drivers, these return codes were ignored, which could lead to a situation where bugs could be missed. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- include/linux/device-mapper.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'include/linux/device-mapper.h') diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index c17fd334e574..89ff2df40240 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -157,8 +157,7 @@ struct dm_target { }; int dm_register_target(struct target_type *t); -int dm_unregister_target(struct target_type *t); - +void dm_unregister_target(struct target_type *t); /*----------------------------------------------------------------- * Functions for creating and manipulating mapped devices. @@ -276,6 +275,9 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size); *---------------------------------------------------------------*/ #define DM_NAME "device-mapper" +#define DMCRIT(f, arg...) \ + printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg) + #define DMERR(f, arg...) \ printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg) #define DMERR_LIMIT(f, arg...) \ -- cgit v1.2.3-70-g09d2 From 7d76345da6ed3927c9cbf5d3f7a7021e8bba7374 Mon Sep 17 00:00:00 2001 From: Kiyoshi Ueda Date: Tue, 6 Jan 2009 03:05:07 +0000 Subject: dm request: extend target interface This patch adds the following target interfaces for request-based dm. map_rq : for mapping a request rq_end_io : for finishing a request busy : for avoiding performance regression from bio-based dm. Target can tell dm core not to map requests now, and that may help requests in the block layer queue to be bigger by I/O merging. In bio-based dm, this behavior is done by device drivers managing the block layer queue. But in request-based dm, dm core has to do that since dm core manages the block layer queue. Signed-off-by: Kiyoshi Ueda Signed-off-by: Jun'ichi Nomura Signed-off-by: Alasdair G Kergon --- include/linux/device-mapper.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux/device-mapper.h') diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 89ff2df40240..c1ba76c7c0e5 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -45,6 +45,8 @@ typedef void (*dm_dtr_fn) (struct dm_target *ti); */ typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio, union map_info *map_context); +typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone, + union map_info *map_context); /* * Returns: @@ -57,6 +59,9 @@ typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio, typedef int (*dm_endio_fn) (struct dm_target *ti, struct bio *bio, int error, union map_info *map_context); +typedef int (*dm_request_endio_fn) (struct dm_target *ti, + struct request *clone, int error, + union map_info *map_context); typedef void (*dm_flush_fn) (struct dm_target *ti); typedef void (*dm_presuspend_fn) (struct dm_target *ti); @@ -75,6 +80,13 @@ typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd, typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm, struct bio_vec *biovec, int max_size); +/* + * Returns: + * 0: The target can handle the next I/O immediately. + * 1: The target can't handle the next I/O immediately. + */ +typedef int (*dm_busy_fn) (struct dm_target *ti); + void dm_error(const char *message); /* @@ -107,7 +119,9 @@ struct target_type { dm_ctr_fn ctr; dm_dtr_fn dtr; dm_map_fn map; + dm_map_request_fn map_rq; dm_endio_fn end_io; + dm_request_endio_fn rq_end_io; dm_flush_fn flush; dm_presuspend_fn presuspend; dm_postsuspend_fn postsuspend; @@ -117,6 +131,7 @@ struct target_type { dm_message_fn message; dm_ioctl_fn ioctl; dm_merge_fn merge; + dm_busy_fn busy; }; struct io_restrictions { -- cgit v1.2.3-70-g09d2 From ab4c1424882be9cd70b89abf2b484add355712fa Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Tue, 6 Jan 2009 03:05:09 +0000 Subject: dm: support barriers on simple devices Implement barrier support for single device DM devices This patch implements barrier support in DM for the common case of dm linear just remapping a single underlying device. In this case we can safely pass the barrier through because there can be no reordering between devices. NB. Any DM device might cease to support barriers if it gets reconfigured so code must continue to allow for a possible -EOPNOTSUPP on every barrier bio submitted. - agk Signed-off-by: Andi Kleen Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- drivers/md/dm-linear.c | 1 + drivers/md/dm-table.c | 19 +++++++++++++++++++ drivers/md/dm.c | 15 +++++---------- drivers/md/dm.h | 1 + include/linux/device-mapper.h | 7 +++++++ 5 files changed, 33 insertions(+), 10 deletions(-) (limited to 'include/linux/device-mapper.h') diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c index 79fb53e51c70..bfa107f59d96 100644 --- a/drivers/md/dm-linear.c +++ b/drivers/md/dm-linear.c @@ -142,6 +142,7 @@ static struct target_type linear_target = { .status = linear_status, .ioctl = linear_ioctl, .merge = linear_merge, + .features = DM_TARGET_SUPPORTS_BARRIERS, }; int __init dm_linear_init(void) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 04e5fd742c2c..ebaaf72cd822 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -38,6 +38,8 @@ struct dm_table { sector_t *highs; struct dm_target *targets; + unsigned barriers_supported:1; + /* * Indicates the rw permissions for the new logical * device. This should be a combination of FMODE_READ @@ -227,6 +229,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode, INIT_LIST_HEAD(&t->devices); atomic_set(&t->holders, 1); + t->barriers_supported = 1; if (!num_targets) num_targets = KEYS_PER_NODE; @@ -728,6 +731,10 @@ int dm_table_add_target(struct dm_table *t, const char *type, /* FIXME: the plan is to combine high here and then have * the merge fn apply the target level restrictions. */ combine_restrictions_low(&t->limits, &tgt->limits); + + if (!(tgt->type->features & DM_TARGET_SUPPORTS_BARRIERS)) + t->barriers_supported = 0; + return 0; bad: @@ -772,6 +779,12 @@ int dm_table_complete(struct dm_table *t) check_for_valid_limits(&t->limits); + /* + * We only support barriers if there is exactly one underlying device. + */ + if (!list_is_singular(&t->devices)) + t->barriers_supported = 0; + /* how many indexes will the btree have ? */ leaf_nodes = dm_div_up(t->num_targets, KEYS_PER_NODE); t->depth = 1 + int_log(leaf_nodes, CHILDREN_PER_NODE); @@ -986,6 +999,12 @@ struct mapped_device *dm_table_get_md(struct dm_table *t) return t->md; } +int dm_table_barrier_ok(struct dm_table *t) +{ + return t->barriers_supported; +} +EXPORT_SYMBOL(dm_table_barrier_ok); + EXPORT_SYMBOL(dm_vcalloc); EXPORT_SYMBOL(dm_get_device); EXPORT_SYMBOL(dm_put_device); diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4882ce7e88a3..dd953b189f45 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -835,7 +835,11 @@ static int __split_bio(struct mapped_device *md, struct bio *bio) ci.map = dm_get_table(md); if (unlikely(!ci.map)) return -EIO; - + if (unlikely(bio_barrier(bio) && !dm_table_barrier_ok(ci.map))) { + dm_table_put(ci.map); + bio_endio(bio, -EOPNOTSUPP); + return 0; + } ci.md = md; ci.bio = bio; ci.io = alloc_io(md); @@ -919,15 +923,6 @@ static int dm_request(struct request_queue *q, struct bio *bio) struct mapped_device *md = q->queuedata; int cpu; - /* - * There is no use in forwarding any barrier request since we can't - * guarantee it is (or can be) handled by the targets correctly. - */ - if (unlikely(bio_barrier(bio))) { - bio_endio(bio, -EOPNOTSUPP); - return 0; - } - down_read(&md->io_lock); cpu = part_stat_lock(); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 0ade60cdef42..5b5d08ba9e92 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -51,6 +51,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits); * To check the return value from dm_table_find_target(). */ #define dm_target_is_valid(t) ((t)->table) +int dm_table_barrier_ok(struct dm_table *t); /*----------------------------------------------------------------- * A registry of target types. diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index c1ba76c7c0e5..8209e08969f9 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -112,7 +112,14 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d); /* * Information about a target type */ + +/* + * Target features + */ +#define DM_TARGET_SUPPORTS_BARRIERS 0x00000001 + struct target_type { + uint64_t features; const char *name; struct module *module; unsigned version[3]; -- cgit v1.2.3-70-g09d2