1 files changed, 71 insertions, 1 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 467c586e2439..bb28f9782bdd 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -20,9 +20,9 @@
 #include <linux/vmalloc.h>
 #include <linux/log2.h>
 #include <linux/dm-kcopyd.h>
+#include <linux/workqueue.h>
 
 #include "dm-exception-store.h"
-#include "dm-snap.h"
 #include "dm-bio-list.h"
 
 #define DM_MSG_PREFIX "snapshots"
@@ -47,9 +47,79 @@
  */
 #define MIN_IOS 256
 
+#define DM_TRACKED_CHUNK_HASH_SIZE      16
+#define DM_TRACKED_CHUNK_HASH(x)        ((unsigned long)(x) & \
+                                         (DM_TRACKED_CHUNK_HASH_SIZE - 1))
+
+struct exception_table {
+        uint32_t hash_mask;
+        unsigned hash_shift;
+        struct list_head *table;
+};
+
+struct dm_snapshot {
+        struct rw_semaphore lock;
+
+        struct dm_dev *origin;
+
+        /* List of snapshots per Origin */
+        struct list_head list;
+
+        /* You can't use a snapshot if this is 0 (e.g. if full) */
+        int valid;
+
+        /* Origin writes don't trigger exceptions until this is set */
+        int active;
+
+        /* Used for display of table */
+        char type;
+
+        mempool_t *pending_pool;
+
+        atomic_t pending_exceptions_count;
+
+        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 dm_exception_store *store;
+
+        struct dm_kcopyd_client *kcopyd_client;
+
+        /* Queue of snapshot writes for ksnapd to flush */
+        struct bio_list queued_bios;
+        struct work_struct queued_bios_work;
+
+        /* Chunks with outstanding reads */
+        mempool_t *tracked_chunk_pool;
+        spinlock_t tracked_chunk_lock;
+        struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
+};
+
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);
 
+static sector_t chunk_to_sector(struct dm_exception_store *store,
+                                chunk_t chunk)
+{
+        return chunk << store->chunk_shift;
+}
+
+static int bdev_equal(struct block_device *lhs, struct block_device *rhs)
+{
+        /*
+         * There is only ever one instance of a particular block
+         * device so we can compare pointers safely.
+         */
+        return lhs == rhs;
+}
+
 struct dm_snap_pending_exception {
         struct dm_snap_exception e;