51 	struct dm_dev *origin;  member
56 	/* List of snapshots per Origin */
72 	/* Origin writes don't trigger exceptions until this is set */
127 	 *   	=> use the origin; forget about the snapshot.
130 	 *         (We can't use the intermediate origin state.)
178 	return s->origin;  in dm_snap_origin()
207 	 * Origin buffers waiting for this to complete are held
238  * Hash table mapping origin volumes to lists of snapshots and
314  * One of these per registered origin, held in the snapshot_origins hash
316 struct origin {  struct
317 	/* The origin device */
322 	/* List of snapshots for this origin */  argument
327  * This structure is allocated for each origin target  argument
337  * Size of the hash table for origin volumes. If we make this
390 static struct origin *__lookup_origin(struct block_device *origin)  in __lookup_origin()  argument
393 	struct origin *o;  in __lookup_origin()
395 	ol = &_origins[origin_hash(origin)];  in __lookup_origin()
397 		if (bdev_equal(o->bdev, origin))  in __lookup_origin()
403 static void __insert_origin(struct origin *o)  in __insert_origin()
409 static struct dm_origin *__lookup_dm_origin(struct block_device *origin)  in __lookup_dm_origin()  argument
414 	ol = &_dm_origins[origin_hash(origin)];  in __lookup_dm_origin()
416 		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()
534 static void __insert_snapshot(struct origin *o, struct dm_snapshot *s)  in __insert_snapshot()
546  * Make a note of the snapshot and its origin so we can look it
547  * up when the origin has a write on it.
555 	struct origin *o, *new_o = NULL;  in register_snapshot()
556 	struct block_device *bdev = snap->origin->bdev;  in register_snapshot()
575 		/* New origin */  in register_snapshot()
598 	struct block_device *bdev = s->origin->bdev;  in reregister_snapshot()
610 	struct origin *o;  in unregister_snapshot()
613 	o = __lookup_origin(s->origin->bdev);  in unregister_snapshot()
851  * Return a minimum chunk size of all snapshots that have the specified origin.
852  * Return zero if the origin has no snapshots.
854 static uint32_t __minimum_chunk_size(struct origin *o)  in __minimum_chunk_size()
1081 	 * from the exception store to the origin  in snapshot_merge_next_chunks()
1085 	dest.bdev = s->origin->bdev;  in snapshot_merge_next_chunks()
1134 	bio_set_dev(flush_bio, s->origin->bdev);  in flush_data()
1291 	r = dm_get_device(ti, origin_path, origin_mode, &s->origin);  in snapshot_ctr()
1293 		ti->error = "Cannot get origin device";  in snapshot_ctr()
1296 	origin_dev = s->origin->bdev->bd_dev;  in snapshot_ctr()
1304 		ti->error = "COW device cannot be the same as origin device";  in snapshot_ctr()
1377 	/* Add snapshot to the list of snapshots for this origin */  in snapshot_ctr()
1381 		ti->error = "Snapshot origin struct allocation failed";  in snapshot_ctr()
1435 	dm_put_device(ti, s->origin);  in snapshot_ctr()
1507 	/* Prevent further origin writes from using this snapshot. */  in snapshot_dtr()
1534 	dm_put_device(ti, s->origin);  in snapshot_dtr()
1601 static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit);
1614 		r = do_origin(s->origin, bio, false);  in retry_origin_bios()
1707 	 * as the pending exception exists, neither origin writes nor snapshot  in pending_complete()
1708 	 * merging can overwrite the chunk in origin.  in pending_complete()
1816 	struct block_device *bdev = s->origin->bdev;  in start_copy()
2007 			 * passdown discard to origin (without triggering  in snapshot_map()
2009 			 * defeat the goal of freeing space in origin that is  in snapshot_map()
2012 			bio_set_dev(bio, s->origin->bdev);  in snapshot_map()
2111 		bio_set_dev(bio, s->origin->bdev);  in snapshot_map()
2124  * target and a snapshot-origin target.  It only generates new
2129  * redirect I/O to the cow device.  Otherwise I/O is sent to the origin,
2145 			bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2161 	/* Full merging snapshots are redirected to the origin */  in snapshot_merge_map()
2173 			bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2187 	bio_set_dev(bio, s->origin->bdev);  in snapshot_merge_map()
2191 		return do_origin(s->origin, bio, false);  in snapshot_merge_map()
2254 	o = __lookup_dm_origin(s->origin->bdev);  in snapshot_resume()
2328 	 * snapshot-merge acts as an origin, so set ti->max_io_len  in snapshot_merge_resume()
2330 	ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev);  in snapshot_merge_resume()
2380 		DMEMIT("%s %s", snap->origin->name, snap->cow->name);  in snapshot_status()
2401 	r = fn(ti, snap->origin, 0, ti->len, data);  in snapshot_iterate_devices()
2431  * Origin methods
2437  * (No remapping actually occurs as the origin is always a direct linear
2456 	/* Do all the snapshots on this origin */  in __origin_write()
2524 		 * If an origin bio was supplied, queue it to wait for the  in __origin_write()
2564  * Called on a write from the origin driver.
2566 static int do_origin(struct dm_dev *origin, struct bio *bio, bool limit)  in do_origin()  argument
2568 	struct origin *o;  in do_origin()
2573 	o = __lookup_origin(origin->bdev);  in do_origin()
2607 	struct origin *o;  in origin_write_extent()
2610 	 * The origin's __minimum_chunk_size() got stored in max_io_len  in origin_write_extent()
2614 	o = __lookup_origin(merging_snap->origin->bdev);  in origin_write_extent()
2625  * Origin: maps a linear range of a device, with hooks for snapshotting.
2629  * Construct an origin mapping: <dev_path>
2630  * The context for an origin is merely a 'struct dm_dev *'
2639 		ti->error = "origin: incorrect number of arguments";  in origin_ctr()
2645 		ti->error = "Cannot allocate private origin structure";  in origin_ctr()
2748 	.name    = "snapshot-origin",
2829 		DMERR("Origin target register failed %d", r);  in dm_snapshot_init()
2877 MODULE_ALIAS("dm-snapshot-origin");