btrfs: implement hole punching for RAID stripe extents

If the stripe extent we want to delete starts before the range we want to
delete and ends after the range we want to delete we're punching a
hole in the stripe extent:

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

This means we need to a) truncate the existing item and b)
create a second item for the remaining range.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index bf665fdef18b..858abf518e9b 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -141,6 +141,54 @@ int btrfs_delete_raid_extent(struct btrfs_trans_handle *trans, u64 start, u64 le
 					       found_start, found_end);
 
 		/*
+		 * The stripe extent starts before the range we want to delete
+		 * and ends after the range we want to delete, i.e. we're
+		 * punching a hole in the stripe extent:
+		 *
+		 *  |--- RAID Stripe Extent ---|
+		 *  | keep |--- drop ---| keep |
+		 *
+		 * This means we need to a) truncate the existing item and b)
+		 * create a second item for the remaining range.
+		 */
+		if (found_start < start && found_end > end) {
+			size_t item_size;
+			u64 diff_start = start - found_start;
+			u64 diff_end = found_end - end;
+			struct btrfs_stripe_extent *extent;
+			struct btrfs_key newkey = {
+				.objectid = end,
+				.type = BTRFS_RAID_STRIPE_KEY,
+				.offset = diff_end,
+			};
+
+			/* The "right" item. */
+			ret = btrfs_duplicate_item(trans, stripe_root, path, &newkey);
+			if (ret)
+				break;
+
+			item_size = btrfs_item_size(leaf, path->slots[0]);
+			extent = btrfs_item_ptr(leaf, path->slots[0],
+						struct btrfs_stripe_extent);
+
+			for (int i = 0; i < btrfs_num_raid_stripes(item_size); i++) {
+				struct btrfs_raid_stride *stride = &extent->strides[i];
+				u64 phys;
+
+				phys = btrfs_raid_stride_physical(leaf, stride);
+				phys += diff_start + length;
+				btrfs_set_raid_stride_physical(leaf, stride, phys);
+			}
+
+			/* The "left" item. */
+			path->slots[0]--;
+			btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+			btrfs_partially_delete_raid_extent(trans, path, &key,
+							   diff_start, 0);
+			break;
+		}
+
+		/*
 		 * The stripe extent starts before the range we want to delete:
 		 *
 		 * |--- RAID Stripe Extent ---|