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authorMikulas Patocka <mpatocka@redhat.com>2009-06-22 13:12:20 +0400
committerAlasdair G Kergon <agk@redhat.com>2009-06-22 13:12:20 +0400
commitf9ab94cee313746573b2d693bc2afb807ebb0998 (patch)
tree150155f364db0f26c7217e1f92d31344aa67a3f0
parent27eaa14975d8b53f0bad422e53cdf8e5f6dd44ec (diff)
downloadlinux-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.c39
-rw-r--r--include/linux/device-mapper.h11
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.
*/