[PATCH] dm snapshot: add workqueue
Add a workqueue so that I/O can be queued up to be flushed from a separate
thread (e.g. if local interrupts are disabled).
A new per-snapshot spinlock pe_lock is introduced to protect queued_bios.
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 221eb88..15fa2ae 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -10,7 +10,9 @@
#define DM_SNAPSHOT_H
#include "dm.h"
+#include "dm-bio-list.h"
#include <linux/blkdev.h>
+#include <linux/workqueue.h>
struct exception_table {
uint32_t hash_mask;
@@ -112,10 +114,20 @@
struct exception_table pending;
struct exception_table complete;
+ /*
+ * pe_lock protects all pending_exception operations and access
+ * as well as the snapshot_bios list.
+ */
+ spinlock_t pe_lock;
+
/* The on disk metadata handler */
struct exception_store store;
struct kcopyd_client *kcopyd_client;
+
+ /* Queue of snapshot writes for ksnapd to flush */
+ struct bio_list queued_bios;
+ struct work_struct queued_bios_work;
};
/*