diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c
new file mode 100644
index 0000000..db9f2c5
--- /dev/null
+++ b/fs/btrfs/delalloc-space.c
@@ -0,0 +1,501 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "ctree.h"
+#include "delalloc-space.h"
+#include "block-rsv.h"
+#include "btrfs_inode.h"
+#include "space-info.h"
+#include "transaction.h"
+#include "qgroup.h"
+#include "block-group.h"
+
+int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
+	u64 used;
+	int ret = 0;
+	int need_commit = 2;
+	int have_pinned_space;
+
+	/* Make sure bytes are sectorsize aligned */
+	bytes = ALIGN(bytes, fs_info->sectorsize);
+
+	if (btrfs_is_free_space_inode(inode)) {
+		need_commit = 0;
+		ASSERT(current->journal_info);
+	}
+
+again:
+	/* Make sure we have enough space to handle the data first */
+	spin_lock(&data_sinfo->lock);
+	used = btrfs_space_info_used(data_sinfo, true);
+
+	if (used + bytes > data_sinfo->total_bytes) {
+		struct btrfs_trans_handle *trans;
+
+		/*
+		 * If we don't have enough free bytes in this space then we need
+		 * to alloc a new chunk.
+		 */
+		if (!data_sinfo->full) {
+			u64 alloc_target;
+
+			data_sinfo->force_alloc = CHUNK_ALLOC_FORCE;
+			spin_unlock(&data_sinfo->lock);
+
+			alloc_target = btrfs_data_alloc_profile(fs_info);
+			/*
+			 * It is ugly that we don't call nolock join
+			 * transaction for the free space inode case here.
+			 * But it is safe because we only do the data space
+			 * reservation for the free space cache in the
+			 * transaction context, the common join transaction
+			 * just increase the counter of the current transaction
+			 * handler, doesn't try to acquire the trans_lock of
+			 * the fs.
+			 */
+			trans = btrfs_join_transaction(root);
+			if (IS_ERR(trans))
+				return PTR_ERR(trans);
+
+			ret = btrfs_chunk_alloc(trans, alloc_target,
+						CHUNK_ALLOC_NO_FORCE);
+			btrfs_end_transaction(trans);
+			if (ret < 0) {
+				if (ret != -ENOSPC)
+					return ret;
+				else {
+					have_pinned_space = 1;
+					goto commit_trans;
+				}
+			}
+
+			goto again;
+		}
+
+		/*
+		 * If we don't have enough pinned space to deal with this
+		 * allocation, and no removed chunk in current transaction,
+		 * don't bother committing the transaction.
+		 */
+		have_pinned_space = __percpu_counter_compare(
+			&data_sinfo->total_bytes_pinned,
+			used + bytes - data_sinfo->total_bytes,
+			BTRFS_TOTAL_BYTES_PINNED_BATCH);
+		spin_unlock(&data_sinfo->lock);
+
+		/* Commit the current transaction and try again */
+commit_trans:
+		if (need_commit) {
+			need_commit--;
+
+			if (need_commit > 0) {
+				btrfs_start_delalloc_roots(fs_info, -1);
+				btrfs_wait_ordered_roots(fs_info, U64_MAX, 0,
+							 (u64)-1);
+			}
+
+			trans = btrfs_join_transaction(root);
+			if (IS_ERR(trans))
+				return PTR_ERR(trans);
+			if (have_pinned_space >= 0 ||
+			    test_bit(BTRFS_TRANS_HAVE_FREE_BGS,
+				     &trans->transaction->flags) ||
+			    need_commit > 0) {
+				ret = btrfs_commit_transaction(trans);
+				if (ret)
+					return ret;
+				/*
+				 * The cleaner kthread might still be doing iput
+				 * operations. Wait for it to finish so that
+				 * more space is released.  We don't need to
+				 * explicitly run the delayed iputs here because
+				 * the commit_transaction would have woken up
+				 * the cleaner.
+				 */
+				ret = btrfs_wait_on_delayed_iputs(fs_info);
+				if (ret)
+					return ret;
+				goto again;
+			} else {
+				btrfs_end_transaction(trans);
+			}
+		}
+
+		trace_btrfs_space_reservation(fs_info,
+					      "space_info:enospc",
+					      data_sinfo->flags, bytes, 1);
+		return -ENOSPC;
+	}
+	btrfs_space_info_update_bytes_may_use(fs_info, data_sinfo, bytes);
+	spin_unlock(&data_sinfo->lock);
+
+	return 0;
+}
+
+int btrfs_check_data_free_space(struct inode *inode,
+			struct extent_changeset **reserved, u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	int ret;
+
+	/* align the range */
+	len = round_up(start + len, fs_info->sectorsize) -
+	      round_down(start, fs_info->sectorsize);
+	start = round_down(start, fs_info->sectorsize);
+
+	ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode), len);
+	if (ret < 0)
+		return ret;
+
+	/* Use new btrfs_qgroup_reserve_data to reserve precious data space. */
+	ret = btrfs_qgroup_reserve_data(inode, reserved, start, len);
+	if (ret < 0)
+		btrfs_free_reserved_data_space_noquota(inode, start, len);
+	else
+		ret = 0;
+	return ret;
+}
+
+/*
+ * Called if we need to clear a data reservation for this inode
+ * Normally in a error case.
+ *
+ * This one will *NOT* use accurate qgroup reserved space API, just for case
+ * which we can't sleep and is sure it won't affect qgroup reserved space.
+ * Like clear_bit_hook().
+ */
+void btrfs_free_reserved_data_space_noquota(struct inode *inode, u64 start,
+					    u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_space_info *data_sinfo;
+
+	/* Make sure the range is aligned to sectorsize */
+	len = round_up(start + len, fs_info->sectorsize) -
+	      round_down(start, fs_info->sectorsize);
+	start = round_down(start, fs_info->sectorsize);
+
+	data_sinfo = fs_info->data_sinfo;
+	spin_lock(&data_sinfo->lock);
+	btrfs_space_info_update_bytes_may_use(fs_info, data_sinfo, -len);
+	spin_unlock(&data_sinfo->lock);
+}
+
+/*
+ * Called if we need to clear a data reservation for this inode
+ * Normally in a error case.
+ *
+ * This one will handle the per-inode data rsv map for accurate reserved
+ * space framework.
+ */
+void btrfs_free_reserved_data_space(struct inode *inode,
+			struct extent_changeset *reserved, u64 start, u64 len)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+
+	/* Make sure the range is aligned to sectorsize */
+	len = round_up(start + len, root->fs_info->sectorsize) -
+	      round_down(start, root->fs_info->sectorsize);
+	start = round_down(start, root->fs_info->sectorsize);
+
+	btrfs_free_reserved_data_space_noquota(inode, start, len);
+	btrfs_qgroup_free_data(inode, reserved, start, len);
+}
+
+/**
+ * btrfs_inode_rsv_release - release any excessive reservation.
+ * @inode - the inode we need to release from.
+ * @qgroup_free - free or convert qgroup meta.
+ *   Unlike normal operation, qgroup meta reservation needs to know if we are
+ *   freeing qgroup reservation or just converting it into per-trans.  Normally
+ *   @qgroup_free is true for error handling, and false for normal release.
+ *
+ * This is the same as btrfs_block_rsv_release, except that it handles the
+ * tracepoint for the reservation.
+ */
+static void btrfs_inode_rsv_release(struct btrfs_inode *inode, bool qgroup_free)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+	u64 released = 0;
+	u64 qgroup_to_release = 0;
+
+	/*
+	 * Since we statically set the block_rsv->size we just want to say we
+	 * are releasing 0 bytes, and then we'll just get the reservation over
+	 * the size free'd.
+	 */
+	released = __btrfs_block_rsv_release(fs_info, block_rsv, 0,
+					     &qgroup_to_release);
+	if (released > 0)
+		trace_btrfs_space_reservation(fs_info, "delalloc",
+					      btrfs_ino(inode), released, 0);
+	if (qgroup_free)
+		btrfs_qgroup_free_meta_prealloc(inode->root, qgroup_to_release);
+	else
+		btrfs_qgroup_convert_reserved_meta(inode->root,
+						   qgroup_to_release);
+}
+
+static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
+						 struct btrfs_inode *inode)
+{
+	struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+	u64 reserve_size = 0;
+	u64 qgroup_rsv_size = 0;
+	u64 csum_leaves;
+	unsigned outstanding_extents;
+
+	lockdep_assert_held(&inode->lock);
+	outstanding_extents = inode->outstanding_extents;
+
+	/*
+	 * Insert size for the number of outstanding extents, 1 normal size for
+	 * updating the inode.
+	 */
+	if (outstanding_extents) {
+		reserve_size = btrfs_calc_insert_metadata_size(fs_info,
+						outstanding_extents);
+		reserve_size += btrfs_calc_metadata_size(fs_info, 1);
+	}
+	csum_leaves = btrfs_csum_bytes_to_leaves(fs_info,
+						 inode->csum_bytes);
+	reserve_size += btrfs_calc_insert_metadata_size(fs_info,
+							csum_leaves);
+	/*
+	 * For qgroup rsv, the calculation is very simple:
+	 * account one nodesize for each outstanding extent
+	 *
+	 * This is overestimating in most cases.
+	 */
+	qgroup_rsv_size = (u64)outstanding_extents * fs_info->nodesize;
+
+	spin_lock(&block_rsv->lock);
+	block_rsv->size = reserve_size;
+	block_rsv->qgroup_rsv_size = qgroup_rsv_size;
+	spin_unlock(&block_rsv->lock);
+}
+
+static void calc_inode_reservations(struct btrfs_fs_info *fs_info,
+				    u64 num_bytes, u64 *meta_reserve,
+				    u64 *qgroup_reserve)
+{
+	u64 nr_extents = count_max_extents(num_bytes);
+	u64 csum_leaves = btrfs_csum_bytes_to_leaves(fs_info, num_bytes);
+	u64 inode_update = btrfs_calc_metadata_size(fs_info, 1);
+
+	*meta_reserve = btrfs_calc_insert_metadata_size(fs_info,
+						nr_extents + csum_leaves);
+
+	/*
+	 * finish_ordered_io has to update the inode, so add the space required
+	 * for an inode update.
+	 */
+	*meta_reserve += inode_update;
+	*qgroup_reserve = nr_extents * fs_info->nodesize;
+}
+
+int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes)
+{
+	struct btrfs_root *root = inode->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+	u64 meta_reserve, qgroup_reserve;
+	unsigned nr_extents;
+	enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_ALL;
+	int ret = 0;
+	bool delalloc_lock = true;
+
+	/*
+	 * If we are a free space inode we need to not flush since we will be in
+	 * the middle of a transaction commit.  We also don't need the delalloc
+	 * mutex since we won't race with anybody.  We need this mostly to make
+	 * lockdep shut its filthy mouth.
+	 *
+	 * If we have a transaction open (can happen if we call truncate_block
+	 * from truncate), then we need FLUSH_LIMIT so we don't deadlock.
+	 */
+	if (btrfs_is_free_space_inode(inode)) {
+		flush = BTRFS_RESERVE_NO_FLUSH;
+		delalloc_lock = false;
+	} else {
+		if (current->journal_info)
+			flush = BTRFS_RESERVE_FLUSH_LIMIT;
+
+		if (btrfs_transaction_in_commit(fs_info))
+			schedule_timeout(1);
+	}
+
+	if (delalloc_lock)
+		mutex_lock(&inode->delalloc_mutex);
+
+	num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
+
+	/*
+	 * We always want to do it this way, every other way is wrong and ends
+	 * in tears.  Pre-reserving the amount we are going to add will always
+	 * be the right way, because otherwise if we have enough parallelism we
+	 * could end up with thousands of inodes all holding little bits of
+	 * reservations they were able to make previously and the only way to
+	 * reclaim that space is to ENOSPC out the operations and clear
+	 * everything out and try again, which is bad.  This way we just
+	 * over-reserve slightly, and clean up the mess when we are done.
+	 */
+	calc_inode_reservations(fs_info, num_bytes, &meta_reserve,
+				&qgroup_reserve);
+	ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserve, true);
+	if (ret)
+		goto out_fail;
+	ret = btrfs_reserve_metadata_bytes(root, block_rsv, meta_reserve, flush);
+	if (ret)
+		goto out_qgroup;
+
+	/*
+	 * Now we need to update our outstanding extents and csum bytes _first_
+	 * and then add the reservation to the block_rsv.  This keeps us from
+	 * racing with an ordered completion or some such that would think it
+	 * needs to free the reservation we just made.
+	 */
+	spin_lock(&inode->lock);
+	nr_extents = count_max_extents(num_bytes);
+	btrfs_mod_outstanding_extents(inode, nr_extents);
+	inode->csum_bytes += num_bytes;
+	btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+	spin_unlock(&inode->lock);
+
+	/* Now we can safely add our space to our block rsv */
+	btrfs_block_rsv_add_bytes(block_rsv, meta_reserve, false);
+	trace_btrfs_space_reservation(root->fs_info, "delalloc",
+				      btrfs_ino(inode), meta_reserve, 1);
+
+	spin_lock(&block_rsv->lock);
+	block_rsv->qgroup_rsv_reserved += qgroup_reserve;
+	spin_unlock(&block_rsv->lock);
+
+	if (delalloc_lock)
+		mutex_unlock(&inode->delalloc_mutex);
+	return 0;
+out_qgroup:
+	btrfs_qgroup_free_meta_prealloc(root, qgroup_reserve);
+out_fail:
+	if (delalloc_lock)
+		mutex_unlock(&inode->delalloc_mutex);
+	return ret;
+}
+
+/**
+ * btrfs_delalloc_release_metadata - release a metadata reservation for an inode
+ * @inode: the inode to release the reservation for.
+ * @num_bytes: the number of bytes we are releasing.
+ * @qgroup_free: free qgroup reservation or convert it to per-trans reservation
+ *
+ * This will release the metadata reservation for an inode.  This can be called
+ * once we complete IO for a given set of bytes to release their metadata
+ * reservations, or on error for the same reason.
+ */
+void btrfs_delalloc_release_metadata(struct btrfs_inode *inode, u64 num_bytes,
+				     bool qgroup_free)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
+	spin_lock(&inode->lock);
+	inode->csum_bytes -= num_bytes;
+	btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+	spin_unlock(&inode->lock);
+
+	if (btrfs_is_testing(fs_info))
+		return;
+
+	btrfs_inode_rsv_release(inode, qgroup_free);
+}
+
+/**
+ * btrfs_delalloc_release_extents - release our outstanding_extents
+ * @inode: the inode to balance the reservation for.
+ * @num_bytes: the number of bytes we originally reserved with
+ *
+ * When we reserve space we increase outstanding_extents for the extents we may
+ * add.  Once we've set the range as delalloc or created our ordered extents we
+ * have outstanding_extents to track the real usage, so we use this to free our
+ * temporarily tracked outstanding_extents.  This _must_ be used in conjunction
+ * with btrfs_delalloc_reserve_metadata.
+ */
+void btrfs_delalloc_release_extents(struct btrfs_inode *inode, u64 num_bytes)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	unsigned num_extents;
+
+	spin_lock(&inode->lock);
+	num_extents = count_max_extents(num_bytes);
+	btrfs_mod_outstanding_extents(inode, -num_extents);
+	btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+	spin_unlock(&inode->lock);
+
+	if (btrfs_is_testing(fs_info))
+		return;
+
+	btrfs_inode_rsv_release(inode, true);
+}
+
+/**
+ * btrfs_delalloc_reserve_space - reserve data and metadata space for
+ * delalloc
+ * @inode: inode we're writing to
+ * @start: start range we are writing to
+ * @len: how long the range we are writing to
+ * @reserved: mandatory parameter, record actually reserved qgroup ranges of
+ * 	      current reservation.
+ *
+ * This will do the following things
+ *
+ * - reserve space in data space info for num bytes
+ *   and reserve precious corresponding qgroup space
+ *   (Done in check_data_free_space)
+ *
+ * - reserve space for metadata space, based on the number of outstanding
+ *   extents and how much csums will be needed
+ *   also reserve metadata space in a per root over-reserve method.
+ * - add to the inodes->delalloc_bytes
+ * - add it to the fs_info's delalloc inodes list.
+ *   (Above 3 all done in delalloc_reserve_metadata)
+ *
+ * Return 0 for success
+ * Return <0 for error(-ENOSPC or -EQUOT)
+ */
+int btrfs_delalloc_reserve_space(struct inode *inode,
+			struct extent_changeset **reserved, u64 start, u64 len)
+{
+	int ret;
+
+	ret = btrfs_check_data_free_space(inode, reserved, start, len);
+	if (ret < 0)
+		return ret;
+	ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len);
+	if (ret < 0)
+		btrfs_free_reserved_data_space(inode, *reserved, start, len);
+	return ret;
+}
+
+/**
+ * btrfs_delalloc_release_space - release data and metadata space for delalloc
+ * @inode: inode we're releasing space for
+ * @start: start position of the space already reserved
+ * @len: the len of the space already reserved
+ * @release_bytes: the len of the space we consumed or didn't use
+ *
+ * This function will release the metadata space that was not used and will
+ * decrement ->delalloc_bytes and remove it from the fs_info delalloc_inodes
+ * list if there are no delalloc bytes left.
+ * Also it will handle the qgroup reserved space.
+ */
+void btrfs_delalloc_release_space(struct inode *inode,
+				  struct extent_changeset *reserved,
+				  u64 start, u64 len, bool qgroup_free)
+{
+	btrfs_delalloc_release_metadata(BTRFS_I(inode), len, qgroup_free);
+	btrfs_free_reserved_data_space(inode, reserved, start, len);
+}