52 	struct dm_dev *origin;  member
57 	/* List of snapshots per Origin */
73 	/* Origin writes don't trigger exceptions until this is set */
128 	 *	=> use the origin; forget about the snapshot.
131 	 *         (We can't use the intermediate origin state.)
174 	return s->origin;  in dm_snap_origin()
203 	 * Origin buffers waiting for this to complete are held
234  * Hash table mapping origin volumes to lists of snapshots and
312  * One of these per registered origin, held in the snapshot_origins hash
314 struct origin {  struct
315 	/* The origin device */
320 	/* List of snapshots for this origin */  argument
325  * This structure is allocated for each origin target  argument
335  * Size of the hash table for origin volumes. If we make this
388 static struct origin *__lookup_origin(struct block_device *origin)  in __lookup_origin()  argument
391 	struct origin *o;  in __lookup_origin()
393 	ol = &_origins[origin_hash(origin)];  in __lookup_origin()
395 		if (bdev_equal(o->bdev, origin))  in __lookup_origin()
401 static void __insert_origin(struct origin *o)  in __insert_origin()
408 static struct dm_origin *__lookup_dm_origin(struct block_device *origin)  in __lookup_dm_origin()  argument
413 	ol = &_dm_origins[origin_hash(origin)];  in __lookup_dm_origin()
415 		if (bdev_equal(o->dev->bdev, origin))  in __lookup_dm_origin()
438  * snap_merge - an existing snapshot-merge target linked to the same origin.
454 	struct origin *o;  in __find_snapshots_sharing_cow()
458 	o = __lookup_origin(snap->origin->bdev);  in __find_snapshots_sharing_cow()
532 static void __insert_snapshot(struct origin *o, struct dm_snapshot *s)  in __insert_snapshot()
544  * Make a note of the snapshot and its origin so we can look it
545  * up when the origin has a write on it.
553 	struct origin *o, *new_o = NULL;  in register_snapshot()
554 	struct block_device *bdev = snap->origin->bdev;  in register_snapshot()
573 		/* New origin */  in register_snapshot()
596 	struct block_device *bdev = s->origin->bdev;  in reregister_snapshot()
608 	struct origin *o;  in unregister_snapshot()
611 	o = __lookup_origin(s->origin->bdev);  in unregister_snapshot()
850  * Return a minimum chunk size of all snapshots that have the specified origin.
851  * Return zero if the origin has no snapshots.
853 static uint32_t __minimum_chunk_size(struct origin *o)  in __minimum_chunk_size()
1078 	 * from the exception store to the origin  in snapshot_merge_next_chunks()
1082 	dest.bdev = s->origin->bdev;  in snapshot_merge_next_chunks()
1139 	if (blkdev_issue_flush(s->origin->bdev) < 0) {  in merge_callback()
1276 	r = dm_get_device(ti, origin_path, origin_mode, &s->origin);  in snapshot_ctr()
1278 		ti->error = "Cannot get origin device";  in snapshot_ctr()
1291 	if (s->cow->bdev && s->cow->bdev == s->origin->bdev) {  in snapshot_ctr()
1292 		ti->error = "COW device cannot be the same as origin device";  in snapshot_ctr()
1358 	/* Add snapshot to the list of snapshots for this origin */  in snapshot_ctr()
1362 		ti->error = "Snapshot origin struct allocation failed";  in snapshot_ctr()
1416 	dm_put_device(ti, s->origin);  in snapshot_ctr()
1488 	/* Prevent further origin writes from using this snapshot. */  in snapshot_dtr()
1513 	dm_put_device(ti, s->origin);  in snapshot_dtr()
1581 static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit);
1594 		r = do_origin(s->origin, bio, false);  in retry_origin_bios()
1687 	 * as the pending exception exists, neither origin writes nor snapshot  in pending_complete()
1688 	 * merging can overwrite the chunk in origin.  in pending_complete()
1796 	struct block_device *bdev = s->origin->bdev;  in start_copy()
1987 			 * passdown discard to origin (without triggering  in snapshot_map()
1989 			 * defeat the goal of freeing space in origin that is  in snapshot_map()
1992 			bio_set_dev(bio, s->origin->bdev);  in snapshot_map()
2091 		bio_set_dev(bio, s->origin->bdev);  in snapshot_map()
2104  * target and a snapshot-origin target.  It only generates new
2109  * redirect I/O to the cow device.  Otherwise I/O is sent to the origin,
2125 			bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2141 	/* Full merging snapshots are redirected to the origin */  in snapshot_merge_map()
2153 			bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2167 	bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2171 		return do_origin(s->origin, bio, false);  in snapshot_merge_map()
2232 	o = __lookup_dm_origin(s->origin->bdev);  in snapshot_resume()
2306 	 * snapshot-merge acts as an origin, so set ti->max_io_len  in snapshot_merge_resume()
2308 	ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev);  in snapshot_merge_resume()
2357 		DMEMIT("%s %s", snap->origin->name, snap->cow->name);  in snapshot_status()
2372 		DMEMIT(",snap_origin_name=%s", snap->origin->name);  in snapshot_status()
2388 	r = fn(ti, snap->origin, 0, ti->len, data);  in snapshot_iterate_devices()
2419  * Origin methods
2425  * (No remapping actually occurs as the origin is always a direct linear
2444 	/* Do all the snapshots on this origin */  in __origin_write()
2512 		 * If an origin bio was supplied, queue it to wait for the  in __origin_write()
2552  * Called on a write from the origin driver.
2554 static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit)  in do_origin()  argument
2556 	struct origin *o;  in do_origin()
2561 	o = __lookup_origin(origin->bdev);  in do_origin()
2596 	struct origin *o;  in origin_write_extent()
2599 	 * The origin's __minimum_chunk_size() got stored in max_io_len  in origin_write_extent()
2603 	o = __lookup_origin(merging_snap->origin->bdev);  in origin_write_extent()
2614  * Origin: maps a linear range of a device, with hooks for snapshotting.
2618  * Construct an origin mapping: <dev_path>
2619  * The context for an origin is merely a 'struct dm_dev *'
2628 		ti->error = "origin: incorrect number of arguments";  in origin_ctr()
2634 		ti->error = "Cannot allocate private origin structure";  in origin_ctr()
2740 	.name    = "snapshot-origin",
2863 MODULE_ALIAS("dm-snapshot-origin");