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-rw-r--r--drivers/md/dm-linear.c1
-rw-r--r--drivers/md/dm-table.c19
-rw-r--r--drivers/md/dm.c15
-rw-r--r--drivers/md/dm.h1
-rw-r--r--include/linux/device-mapper.h7
5 files changed, 33 insertions, 10 deletions
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 79fb53e51c7..bfa107f59d9 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 04e5fd742c2..ebaaf72cd82 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 4882ce7e88a..dd953b189f4 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 0ade60cdef4..5b5d08ba9e9 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 c1ba76c7c0e..8209e08969f 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];