Commit 76643119 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by David Sterba
Browse files

btrfs: fix deletion of a range spanning parts two RAID stripe extents 



When a user requests the deletion of a range that spans multiple stripe
extents and btrfs_search_slot() returns us the second RAID stripe extent,
we need to pick the previous item and truncate it, if there's still a
range to delete left, move on to the next item.

The following diagram illustrates the operation:

 |--- RAID Stripe Extent ---||--- RAID Stripe Extent ---|
        |--- keep  ---|--- drop ---|

While at it, comment the trivial case of a whole item delete as well.

Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 50cae2ca

fs/btrfs/raid-stripe-tree.c

+32 −0
Original line number Diff line number Diff line
@@ -99,6 +99,37 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le 
		found_end = found_start + key.offset;

		ret = 0;



		/*

		 * The stripe extent starts before the range we want to delete,

		 * but the range spans more than one stripe extent:

		 *

		 * |--- RAID Stripe Extent ---||--- RAID Stripe Extent ---|

		 *        |--- keep  ---|--- drop ---|

		 *

		 * This means we have to get the previous item, truncate its

		 * length and then restart the search.

		 */

		if (found_start > start) {

			if (slot == 0) {

				ret = btrfs_previous_item(stripe_root, path, start,

							  BTRFS_RAID_STRIPE_KEY);

				if (ret) {

					if (ret > 0)

						ret = -ENOENT;

					break;

				}

			} else {

				path->slots[0]--;

			}



			leaf = path->nodes[0];

			slot = path->slots[0];

			btrfs_item_key_to_cpu(leaf, &key, slot);

			found_start = key.objectid;

			found_end = found_start + key.offset;

			ASSERT(found_start <= start);

		}



		if (key.type != BTRFS_RAID_STRIPE_KEY)

			break;
@@ -152,6 +183,7 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le 
			break;

		}



		/* Finally we can delete the whole item, no more special cases. */

		ret = btrfs_del_item(trans, stripe_root, path);

		if (ret)

			break;