Reinstate dm_flush_all and dm_table_flush_all. dm_blk_close will
now trigger the .flush method of all targets within a table on the last
close of a DM device.
In the case of the thin target, the thin_flush method will commit the
backing pool's metadata.
Doing so avoids a deadlock that has been observed with the following
sequence (as can be triggered via "dmsetup remove_all"):
- IO is issued to a thin device, thin device is closed
- pool's metadata device is suspended before the pool is
- because the pool still has outstanding IO we deadlock because the
pool's metadata device is suspended
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/md/dm-table.c | 9 +++++++++
drivers/md/dm-thin.c | 19 +++++++++++++++++++
drivers/md/dm.c | 20 +++++++++++++++++++-
drivers/md/dm.h | 1 +
4 files changed, 48 insertions(+), 1 deletions(-)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 2e227fb..077fff8 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1487,6 +1487,15 @@ int dm_table_resume_targets(struct dm_table *t)
return 0;
}
+void dm_table_flush_all(struct dm_table *t)
+{
+ unsigned i;
+
+ for (i = 0; i < t->num_targets; i++)
+ if (t->targets[i].type->flush)
+ t->targets[i].type->flush(&t->targets[i]);
+}
+
void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb)
{
list_add(&cb->list, &t->target_callbacks);
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index c514078..f64c7e6 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2429,6 +2429,24 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
set_discard_limits(pool, limits);
}
+static void thin_flush(struct dm_target *ti)
+{
+ int r;
+ struct thin_c *tc = ti->private;
+ struct pool *pool = tc->pool;
+
+ /*
+ * A bit heavy-handed but the only existing way to batch
+ * metadata commits is to issue() a FLUSH bio -- but DM
+ * doesn't allocate bios outside the DM core.
+ */
+ r = dm_pool_commit_metadata(pool->pmd);
+ if (r < 0) {
+ DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ }
+}
+
static struct target_type thin_target = {
.name = "thin",
.version = {1, 1, 0},
@@ -2441,6 +2459,7 @@ static struct target_type thin_target = {
.status = thin_status,
.iterate_devices = thin_iterate_devices,
.io_hints = thin_io_hints,
+ .flush = thin_flush,
};
/*----------------------------------------------------------------*/
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 23a1a84..715ee57 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -487,6 +487,16 @@ out:
return md ? 0 : -ENXIO;
}
+static void dm_flush_all(struct mapped_device *md)
+{
+ struct dm_table *t = dm_get_live_table(md);
+
+ if (t) {
+ dm_table_flush_all(t);
+ dm_table_put(t);
+ }
+}
+
static int dm_blk_close(struct gendisk *disk, fmode_t mode)
{
struct mapped_device *md = disk->private_data;
@@ -494,10 +504,17 @@ static int dm_blk_close(struct gendisk *disk, fmode_t mode)
spin_lock(&_minor_lock);
atomic_dec(&md->open_count);
- dm_put(md);
spin_unlock(&_minor_lock);
+ /*
+ * Flush all targets on last close
+ */
+ if (!dm_open_count(md))
+ dm_flush_all(md);
+
+ dm_put(md);
+
return 0;
}
@@ -2468,6 +2485,7 @@ void dm_destroy_immediate(struct mapped_device *md)
void dm_put(struct mapped_device *md)
{
atomic_dec(&md->holders);
+ smp_mb__after_atomic_dec();
}
EXPORT_SYMBOL_GPL(dm_put);
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index b7dacd5..82199a1 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -66,6 +66,7 @@ bool dm_table_supports_discards(struct dm_table *t);
int dm_table_alloc_md_mempools(struct dm_table *t);
void dm_table_free_md_mempools(struct dm_table *t);
struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
+void dm_table_flush_all(struct dm_table *t);
int dm_queue_merge_is_compulsory(struct request_queue *q);
--
1.7.1
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
