diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2009-06-22 13:12:20 +0400 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2009-06-22 13:12:20 +0400 |
| commit | f9ab94cee313746573b2d693bc2afb807ebb0998 (patch) | |
| tree | 150155f364db0f26c7217e1f92d31344aa67a3f0 | |
| parent | 27eaa14975d8b53f0bad422e53cdf8e5f6dd44ec (diff) | |
| download | linux-f9ab94cee313746573b2d693bc2afb807ebb0998.tar.xz | |
dm: introduce num_flush_requests
Introduce num_flush_requests for a target to set to say how many flush
instructions (empty barriers) it wants to receive. These are sent by
__clone_and_map_empty_barrier with map_info->flush_request going from 0
to (num_flush_requests - 1).
Old targets without flush support won't receive any flush requests.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | drivers/md/dm.c | 39 | ||||
| -rw-r--r-- | include/linux/device-mapper.h | 11 |
2 files changed, 50 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 7d9ca7094337..badb7519cccb 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -750,6 +750,40 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector, return clone; } +static void __flush_target(struct clone_info *ci, struct dm_target *ti, + unsigned flush_nr) +{ + struct dm_target_io *tio = alloc_tio(ci->md); + struct bio *clone; + + tio->io = ci->io; + tio->ti = ti; + + memset(&tio->info, 0, sizeof(tio->info)); + tio->info.flush_request = flush_nr; + + clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs); + __bio_clone(clone, ci->bio); + clone->bi_destructor = dm_bio_destructor; + + __map_bio(ti, clone, tio); +} + +static int __clone_and_map_empty_barrier(struct clone_info *ci) +{ + unsigned target_nr = 0, flush_nr; + struct dm_target *ti; + + while ((ti = dm_table_get_target(ci->map, target_nr++))) + for (flush_nr = 0; flush_nr < ti->num_flush_requests; + flush_nr++) + __flush_target(ci, ti, flush_nr); + + ci->sector_count = 0; + + return 0; +} + static int __clone_and_map(struct clone_info *ci) { struct bio *clone, *bio = ci->bio; @@ -757,6 +791,9 @@ static int __clone_and_map(struct clone_info *ci) sector_t len = 0, max; struct dm_target_io *tio; + if (unlikely(bio_empty_barrier(bio))) + return __clone_and_map_empty_barrier(ci); + ti = dm_table_find_target(ci->map, ci->sector); if (!dm_target_is_valid(ti)) return -EIO; @@ -877,6 +914,8 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio) ci.io->md = md; ci.sector = bio->bi_sector; ci.sector_count = bio_sectors(bio); + if (unlikely(bio_empty_barrier(bio))) + ci.sector_count = 1; ci.idx = bio->bi_idx; start_io_acct(ci.io); diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 49c2362977fd..fc36a4d07723 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -21,6 +21,7 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t; union map_info { void *ptr; unsigned long long ll; + unsigned flush_request; }; /* @@ -168,6 +169,16 @@ struct dm_target { sector_t split_io; /* + * A number of zero-length barrier requests that will be submitted + * to the target for the purpose of flushing cache. + * + * The request number will be placed in union map_info->flush_request. + * It is a responsibility of the target driver to remap these requests + * to the real underlying devices. + */ + unsigned num_flush_requests; + + /* * These are automatically filled in by * dm_table_get_device. */ |