btrfs: add support for inserting raid stripe extents

Add support for inserting stripe extents into the raid stripe tree on
completion of every write that needs an extra logical-to-physical
translation when using RAID.

Inserting the stripe extents happens after the data I/O has completed,
this is done to

  a) support zone-append and
  b) rule out the possibility of a RAID-write-hole.

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

1 files changed, 87 insertions, 0 deletions

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
new file mode 100644
index 000000000000..c093e0bbb7be
--- /dev/null
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Western Digital Corporation or its affiliates.
+ */
+
+#include <linux/btrfs_tree.h>
+#include "ctree.h"
+#include "fs.h"
+#include "accessors.h"
+#include "transaction.h"
+#include "disk-io.h"
+#include "raid-stripe-tree.h"
+#include "volumes.h"
+#include "misc.h"
+#include "print-tree.h"
+
+static int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
+					struct btrfs_io_context *bioc)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	struct btrfs_key stripe_key;
+	struct btrfs_root *stripe_root = fs_info->stripe_root;
+	const int num_stripes = btrfs_bg_type_to_factor(bioc->map_type);
+	u8 encoding = btrfs_bg_flags_to_raid_index(bioc->map_type);
+	struct btrfs_stripe_extent *stripe_extent;
+	const size_t item_size = struct_size(stripe_extent, strides, num_stripes);
+	int ret;
+
+	stripe_extent = kzalloc(item_size, GFP_NOFS);
+	if (!stripe_extent) {
+		btrfs_abort_transaction(trans, -ENOMEM);
+		btrfs_end_transaction(trans);
+		return -ENOMEM;
+	}
+
+	btrfs_set_stack_stripe_extent_encoding(stripe_extent, encoding);
+	for (int i = 0; i < num_stripes; i++) {
+		u64 devid = bioc->stripes[i].dev->devid;
+		u64 physical = bioc->stripes[i].physical;
+		u64 length = bioc->stripes[i].length;
+		struct btrfs_raid_stride *raid_stride = &stripe_extent->strides[i];
+
+		if (length == 0)
+			length = bioc->size;
+
+		btrfs_set_stack_raid_stride_devid(raid_stride, devid);
+		btrfs_set_stack_raid_stride_physical(raid_stride, physical);
+	}
+
+	stripe_key.objectid = bioc->logical;
+	stripe_key.type = BTRFS_RAID_STRIPE_KEY;
+	stripe_key.offset = bioc->size;
+
+	ret = btrfs_insert_item(trans, stripe_root, &stripe_key, stripe_extent,
+				item_size);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+
+	kfree(stripe_extent);
+
+	return ret;
+}
+
+int btrfs_insert_raid_extent(struct btrfs_trans_handle *trans,
+			     struct btrfs_ordered_extent *ordered_extent)
+{
+	struct btrfs_io_context *bioc;
+	int ret;
+
+	if (!btrfs_fs_incompat(trans->fs_info, RAID_STRIPE_TREE))
+		return 0;
+
+	list_for_each_entry(bioc, &ordered_extent->bioc_list, rst_ordered_entry) {
+		ret = btrfs_insert_one_raid_extent(trans, bioc);
+		if (ret)
+			return ret;
+	}
+
+	while (!list_empty(&ordered_extent->bioc_list)) {
+		bioc = list_first_entry(&ordered_extent->bioc_list,
+					typeof(*bioc), rst_ordered_entry);
+		list_del(&bioc->rst_ordered_entry);
+		btrfs_put_bioc(bioc);
+	}
+
+	return ret;
+}