1 files changed, 207 insertions, 224 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 380054c94e4b..66c822182ecc 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1307,11 +1307,12 @@ static int prepare_uptodate_page(struct inode *inode,
 				 struct page *page, u64 pos,
 				 bool force_uptodate)
 {
+	struct folio *folio = page_folio(page);
 	int ret = 0;
 
 	if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
 	    !PageUptodate(page)) {
-		ret = btrfs_readpage(NULL, page);
+		ret = btrfs_read_folio(NULL, folio);
 		if (ret)
 			return ret;
 		lock_page(page);
@@ -1321,8 +1322,8 @@ static int prepare_uptodate_page(struct inode *inode,
 		}
 
 		/*
-		 * Since btrfs_readpage() will unlock the page before it
-		 * returns, there is a window where btrfs_releasepage() can be
+		 * Since btrfs_read_folio() will unlock the folio before it
+		 * returns, there is a window where btrfs_release_folio() can be
 		 * called to release the page.  Here we check both inode
 		 * mapping and PagePrivate() to make sure the page was not
 		 * released.
@@ -1460,8 +1461,27 @@ lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
 	return ret;
 }
 
-static int check_can_nocow(struct btrfs_inode *inode, loff_t pos,
-			   size_t *write_bytes, bool nowait)
+/*
+ * Check if we can do nocow write into the range [@pos, @pos + @write_bytes)
+ *
+ * @pos:         File offset.
+ * @write_bytes: The length to write, will be updated to the nocow writeable
+ *               range.
+ *
+ * This function will flush ordered extents in the range to ensure proper
+ * nocow checks.
+ *
+ * Return:
+ * > 0          If we can nocow, and updates @write_bytes.
+ *  0           If we can't do a nocow write.
+ * -EAGAIN      If we can't do a nocow write because snapshoting of the inode's
+ *              root is in progress.
+ * < 0          If an error happened.
+ *
+ * NOTE: Callers need to call btrfs_check_nocow_unlock() if we return > 0.
+ */
+int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
+			   size_t *write_bytes)
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_root *root = inode->root;
@@ -1472,7 +1492,7 @@ static int check_can_nocow(struct btrfs_inode *inode, loff_t pos,
 	if (!(inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
 		return 0;
 
-	if (!nowait && !btrfs_drew_try_write_lock(&root->snapshot_lock))
+	if (!btrfs_drew_try_write_lock(&root->snapshot_lock))
 		return -EAGAIN;
 
 	lockstart = round_down(pos, fs_info->sectorsize);
@@ -1480,71 +1500,21 @@ static int check_can_nocow(struct btrfs_inode *inode, loff_t pos,
 			   fs_info->sectorsize) - 1;
 	num_bytes = lockend - lockstart + 1;
 
-	if (nowait) {
-		struct btrfs_ordered_extent *ordered;
-
-		if (!try_lock_extent(&inode->io_tree, lockstart, lockend))
-			return -EAGAIN;
-
-		ordered = btrfs_lookup_ordered_range(inode, lockstart,
-						     num_bytes);
-		if (ordered) {
-			btrfs_put_ordered_extent(ordered);
-			ret = -EAGAIN;
-			goto out_unlock;
-		}
-	} else {
-		btrfs_lock_and_flush_ordered_range(inode, lockstart,
-						   lockend, NULL);
-	}
-
+	btrfs_lock_and_flush_ordered_range(inode, lockstart, lockend, NULL);
 	ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,
 			NULL, NULL, NULL, false);
 	if (ret <= 0) {
 		ret = 0;
-		if (!nowait)
-			btrfs_drew_write_unlock(&root->snapshot_lock);
+		btrfs_drew_write_unlock(&root->snapshot_lock);
 	} else {
 		*write_bytes = min_t(size_t, *write_bytes ,
 				     num_bytes - pos + lockstart);
 	}
-out_unlock:
 	unlock_extent(&inode->io_tree, lockstart, lockend);
 
 	return ret;
 }
 
-static int check_nocow_nolock(struct btrfs_inode *inode, loff_t pos,
-			      size_t *write_bytes)
-{
-	return check_can_nocow(inode, pos, write_bytes, true);
-}
-
-/*
- * Check if we can do nocow write into the range [@pos, @pos + @write_bytes)
- *
- * @pos:	 File offset
- * @write_bytes: The length to write, will be updated to the nocow writeable
- *		 range
- *
- * This function will flush ordered extents in the range to ensure proper
- * nocow checks.
- *
- * Return:
- * >0		and update @write_bytes if we can do nocow write
- *  0		if we can't do nocow write
- * -EAGAIN	if we can't get the needed lock or there are ordered extents
- * 		for * (nowait == true) case
- * <0		if other error happened
- *
- * NOTE: Callers need to release the lock by btrfs_check_nocow_unlock().
- */
-int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
-			   size_t *write_bytes)
-{
-	return check_can_nocow(inode, pos, write_bytes, false);
-}
-
 void btrfs_check_nocow_unlock(struct btrfs_inode *inode)
 {
 	btrfs_drew_write_unlock(&inode->root->snapshot_lock);
@@ -1579,20 +1549,15 @@ static int btrfs_write_check(struct kiocb *iocb, struct iov_iter *from,
 	loff_t oldsize;
 	loff_t start_pos;
 
-	if (iocb->ki_flags & IOCB_NOWAIT) {
-		size_t nocow_bytes = count;
-
-		/* We will allocate space in case nodatacow is not set, so bail */
-		if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes) <= 0)
-			return -EAGAIN;
-		/*
-		 * There are holes in the range or parts of the range that must
-		 * be COWed (shared extents, RO block groups, etc), so just bail
-		 * out.
-		 */
-		if (nocow_bytes < count)
-			return -EAGAIN;
-	}
+	/*
+	 * Quickly bail out on NOWAIT writes if we don't have the nodatacow or
+	 * prealloc flags, as without those flags we always have to COW. We will
+	 * later check if we can really COW into the target range (using
+	 * can_nocow_extent() at btrfs_get_blocks_direct_write()).
+	 */
+	if ((iocb->ki_flags & IOCB_NOWAIT) &&
+	    !(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
+		return -EAGAIN;
 
 	current->backing_dev_info = inode_to_bdi(inode);
 	ret = file_remove_privs(file);
@@ -1720,7 +1685,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		WARN_ON(reserve_bytes == 0);
 		ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
 						      reserve_bytes,
-						      reserve_bytes);
+						      reserve_bytes, false);
 		if (ret) {
 			if (!only_release_metadata)
 				btrfs_free_reserved_data_space(BTRFS_I(inode),
@@ -1883,7 +1848,6 @@ static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
 
 static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 {
-	const bool is_sync_write = (iocb->ki_flags & IOCB_DSYNC);
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
@@ -1937,15 +1901,6 @@ relock:
 	}
 
 	/*
-	 * We remove IOCB_DSYNC so that we don't deadlock when iomap_dio_rw()
-	 * calls generic_write_sync() (through iomap_dio_complete()), because
-	 * that results in calling fsync (btrfs_sync_file()) which will try to
-	 * lock the inode in exclusive/write mode.
-	 */
-	if (is_sync_write)
-		iocb->ki_flags &= ~IOCB_DSYNC;
-
-	/*
 	 * The iov_iter can be mapped to the same file range we are writing to.
 	 * If that's the case, then we will deadlock in the iomap code, because
 	 * it first calls our callback btrfs_dio_iomap_begin(), which will create
@@ -1965,8 +1920,7 @@ relock:
 	 */
 again:
 	from->nofault = true;
-	err = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
-			   IOMAP_DIO_PARTIAL, written);
+	err = btrfs_dio_rw(iocb, from, written);
 	from->nofault = false;
 
 	/* No increment (+=) because iomap returns a cumulative value. */
@@ -2001,17 +1955,24 @@ again:
 	btrfs_inode_unlock(inode, ilock_flags);
 
 	/*
-	 * Add back IOCB_DSYNC. Our caller, btrfs_file_write_iter(), will do
-	 * the fsync (call generic_write_sync()).
+	 * If 'err' is -ENOTBLK or we have not written all data, then it means
+	 * we must fallback to buffered IO.
 	 */
-	if (is_sync_write)
-		iocb->ki_flags |= IOCB_DSYNC;
-
-	/* If 'err' is -ENOTBLK then it means we must fallback to buffered IO. */
 	if ((err < 0 && err != -ENOTBLK) || !iov_iter_count(from))
 		goto out;
 
 buffered:
+	/*
+	 * If we are in a NOWAIT context, then return -EAGAIN to signal the caller
+	 * it must retry the operation in a context where blocking is acceptable,
+	 * since we currently don't have NOWAIT semantics support for buffered IO
+	 * and may block there for many reasons (reserving space for example).
+	 */
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		err = -EAGAIN;
+		goto out;
+	}
+
 	pos = iocb->ki_pos;
 	written_buffered = btrfs_buffered_write(iocb, from);
 	if (written_buffered < 0) {
@@ -2074,7 +2035,7 @@ ssize_t btrfs_do_write_iter(struct kiocb *iocb, struct iov_iter *from,
 	struct file *file = iocb->ki_filp;
 	struct btrfs_inode *inode = BTRFS_I(file_inode(file));
 	ssize_t num_written, num_sync;
-	const bool sync = iocb->ki_flags & IOCB_DSYNC;
+	const bool sync = iocb_is_dsync(iocb);
 
 	/*
 	 * If the fs flips readonly due to some impossible error, although we
@@ -2094,9 +2055,11 @@ ssize_t btrfs_do_write_iter(struct kiocb *iocb, struct iov_iter *from,
 		num_written = btrfs_encoded_write(iocb, from, encoded);
 		num_sync = encoded->len;
 	} else if (iocb->ki_flags & IOCB_DIRECT) {
-		num_written = num_sync = btrfs_direct_write(iocb, from);
+		num_written = btrfs_direct_write(iocb, from);
+		num_sync = num_written;
 	} else {
-		num_written = num_sync = btrfs_buffered_write(iocb, from);
+		num_written = btrfs_buffered_write(iocb, from);
+		num_sync = num_written;
 	}
 
 	btrfs_set_inode_last_sub_trans(inode);
@@ -2344,7 +2307,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	btrfs_release_log_ctx_extents(&ctx);
 	if (ret < 0) {
 		/* Fallthrough and commit/free transaction. */
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 	}
 
 	/* we've logged all the items and now have a consistent
@@ -2359,25 +2322,62 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	 */
 	btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
 
-	if (ret != BTRFS_NO_LOG_SYNC) {
+	if (ret == BTRFS_NO_LOG_SYNC) {
+		ret = btrfs_end_transaction(trans);
+		goto out;
+	}
+
+	/* We successfully logged the inode, attempt to sync the log. */
+	if (!ret) {
+		ret = btrfs_sync_log(trans, root, &ctx);
 		if (!ret) {
-			ret = btrfs_sync_log(trans, root, &ctx);
-			if (!ret) {
-				ret = btrfs_end_transaction(trans);
-				goto out;
-			}
-		}
-		if (!full_sync) {
-			ret = btrfs_wait_ordered_range(inode, start, len);
-			if (ret) {
-				btrfs_end_transaction(trans);
-				goto out;
-			}
+			ret = btrfs_end_transaction(trans);
+			goto out;
 		}
-		ret = btrfs_commit_transaction(trans);
-	} else {
+	}
+
+	/*
+	 * At this point we need to commit the transaction because we had
+	 * btrfs_need_log_full_commit() or some other error.
+	 *
+	 * If we didn't do a full sync we have to stop the trans handle, wait on
+	 * the ordered extents, start it again and commit the transaction.  If
+	 * we attempt to wait on the ordered extents here we could deadlock with
+	 * something like fallocate() that is holding the extent lock trying to
+	 * start a transaction while some other thread is trying to commit the
+	 * transaction while we (fsync) are currently holding the transaction
+	 * open.
+	 */
+	if (!full_sync) {
 		ret = btrfs_end_transaction(trans);
+		if (ret)
+			goto out;
+		ret = btrfs_wait_ordered_range(inode, start, len);
+		if (ret)
+			goto out;
+
+		/*
+		 * This is safe to use here because we're only interested in
+		 * making sure the transaction that had the ordered extents is
+		 * committed.  We aren't waiting on anything past this point,
+		 * we're purely getting the transaction and committing it.
+		 */
+		trans = btrfs_attach_transaction_barrier(root);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+
+			/*
+			 * We committed the transaction and there's no currently
+			 * running transaction, this means everything we care
+			 * about made it to disk and we are done.
+			 */
+			if (ret == -ENOENT)
+				ret = 0;
+			goto out;
+		}
 	}
+
+	ret = btrfs_commit_transaction(trans);
 out:
 	ASSERT(list_empty(&ctx.list));
 	err = file_check_and_advance_wb_err(file);
@@ -2401,7 +2401,7 @@ static int btrfs_file_mmap(struct file	*filp, struct vm_area_struct *vma)
 {
 	struct address_space *mapping = filp->f_mapping;
 
-	if (!mapping->a_ops->readpage)
+	if (!mapping->a_ops->read_folio)
 		return -ENOEXEC;
 
 	file_accessed(filp);
@@ -2570,10 +2570,10 @@ static int find_first_non_hole(struct btrfs_inode *inode, u64 *start, u64 *len)
 	return ret;
 }
 
-static int btrfs_punch_hole_lock_range(struct inode *inode,
-				       const u64 lockstart,
-				       const u64 lockend,
-				       struct extent_state **cached_state)
+static void btrfs_punch_hole_lock_range(struct inode *inode,
+					const u64 lockstart,
+					const u64 lockend,
+					struct extent_state **cached_state)
 {
 	/*
 	 * For subpage case, if the range is not at page boundary, we could
@@ -2587,40 +2587,29 @@ static int btrfs_punch_hole_lock_range(struct inode *inode,
 	const u64 page_lockend = round_down(lockend + 1, PAGE_SIZE) - 1;
 
 	while (1) {
-		struct btrfs_ordered_extent *ordered;
-		int ret;
-
 		truncate_pagecache_range(inode, lockstart, lockend);
 
 		lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
 				 cached_state);
-		ordered = btrfs_lookup_first_ordered_extent(BTRFS_I(inode),
-							    lockend);
-
 		/*
-		 * We need to make sure we have no ordered extents in this range
-		 * and nobody raced in and read a page in this range, if we did
-		 * we need to try again.
+		 * We can't have ordered extents in the range, nor dirty/writeback
+		 * pages, because we have locked the inode's VFS lock in exclusive
+		 * mode, we have locked the inode's i_mmap_lock in exclusive mode,
+		 * we have flushed all delalloc in the range and we have waited
+		 * for any ordered extents in the range to complete.
+		 * We can race with anyone reading pages from this range, so after
+		 * locking the range check if we have pages in the range, and if
+		 * we do, unlock the range and retry.
 		 */
-		if ((!ordered ||
-		    (ordered->file_offset + ordered->num_bytes <= lockstart ||
-		     ordered->file_offset > lockend)) &&
-		     !filemap_range_has_page(inode->i_mapping,
-					     page_lockstart, page_lockend)) {
-			if (ordered)
-				btrfs_put_ordered_extent(ordered);
+		if (!filemap_range_has_page(inode->i_mapping, page_lockstart,
+					    page_lockend))
 			break;
-		}
-		if (ordered)
-			btrfs_put_ordered_extent(ordered);
+
 		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
 				     lockend, cached_state);
-		ret = btrfs_wait_ordered_range(inode, lockstart,
-					       lockend - lockstart + 1);
-		if (ret)
-			return ret;
 	}
-	return 0;
+
+	btrfs_assert_inode_range_clean(BTRFS_I(inode), lockstart, lockend);
 }
 
 static int btrfs_insert_replace_extent(struct btrfs_trans_handle *trans,
@@ -2744,7 +2733,7 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 		goto out;
 	}
 	rsv->size = btrfs_calc_insert_metadata_size(fs_info, 1);
-	rsv->failfast = 1;
+	rsv->failfast = true;
 
 	/*
 	 * 1 - update the inode
@@ -2766,7 +2755,8 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 
 	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
 				      min_size, false);
-	BUG_ON(ret);
+	if (WARN_ON(ret))
+		goto out_trans;
 	trans->block_rsv = rsv;
 
 	cur_offset = start;
@@ -2850,6 +2840,25 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 			extent_info->file_offset += replace_len;
 		}
 
+		/*
+		 * We are releasing our handle on the transaction, balance the
+		 * dirty pages of the btree inode and flush delayed items, and
+		 * then get a new transaction handle, which may now point to a
+		 * new transaction in case someone else may have committed the
+		 * transaction we used to replace/drop file extent items. So
+		 * bump the inode's iversion and update mtime and ctime except
+		 * if we are called from a dedupe context. This is because a
+		 * power failure/crash may happen after the transaction is
+		 * committed and before we finish replacing/dropping all the
+		 * file extent items we need.
+		 */
+		inode_inc_iversion(&inode->vfs_inode);
+
+		if (!extent_info || extent_info->update_times) {
+			inode->vfs_inode.i_mtime = current_time(&inode->vfs_inode);
+			inode->vfs_inode.i_ctime = inode->vfs_inode.i_mtime;
+		}
+
 		ret = btrfs_update_inode(trans, root, inode);
 		if (ret)
 			break;
@@ -2866,7 +2875,8 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 
 		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
 					      rsv, min_size, false);
-		BUG_ON(ret);	/* shouldn't happen */
+		if (WARN_ON(ret))
+			break;
 		trans->block_rsv = rsv;
 
 		cur_offset = drop_args.drop_end;
@@ -2976,11 +2986,12 @@ static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len)
 	bool truncated_block = false;
 	bool updated_inode = false;
 
+	btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
+
 	ret = btrfs_wait_ordered_range(inode, offset, len);
 	if (ret)
-		return ret;
+		goto out_only_mutex;
 
-	btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
 	ino_size = round_up(inode->i_size, fs_info->sectorsize);
 	ret = find_first_non_hole(BTRFS_I(inode), &offset, &len);
 	if (ret < 0)
@@ -3072,10 +3083,7 @@ static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len)
 		goto out_only_mutex;
 	}
 
-	ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
-					  &cached_state);
-	if (ret)
-		goto out_only_mutex;
+	btrfs_punch_hole_lock_range(inode, lockstart, lockend, &cached_state);
 
 	path = btrfs_alloc_path();
 	if (!path) {
@@ -3091,7 +3099,8 @@ static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len)
 
 	ASSERT(trans != NULL);
 	inode_inc_iversion(inode);
-	inode->i_mtime = inode->i_ctime = current_time(inode);
+	inode->i_mtime = current_time(inode);
+	inode->i_ctime = inode->i_mtime;
 	ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
 	updated_inode = true;
 	btrfs_end_transaction(trans);
@@ -3237,8 +3246,6 @@ static int btrfs_zero_range(struct inode *inode,
 	u64 bytes_to_reserve = 0;
 	bool space_reserved = false;
 
-	inode_dio_wait(inode);
-
 	em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, alloc_start,
 			      alloc_end - alloc_start);
 	if (IS_ERR(em)) {
@@ -3368,10 +3375,8 @@ reserve_space:
 		if (ret < 0)
 			goto out;
 		space_reserved = true;
-		ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
-						  &cached_state);
-		if (ret)
-			goto out;
+		btrfs_punch_hole_lock_range(inode, lockstart, lockend,
+					    &cached_state);
 		ret = btrfs_qgroup_reserve_data(BTRFS_I(inode), &data_reserved,
 						alloc_start, bytes_to_reserve);
 		if (ret) {
@@ -3417,6 +3422,9 @@ static long btrfs_fallocate(struct file *file, int mode,
 	u64 alloc_hint = 0;
 	u64 locked_end;
 	u64 actual_end = 0;
+	u64 data_space_needed = 0;
+	u64 data_space_reserved = 0;
+	u64 qgroup_reserved = 0;
 	struct extent_map *em;
 	int blocksize = btrfs_inode_sectorsize(BTRFS_I(inode));
 	int ret;
@@ -3437,18 +3445,6 @@ static long btrfs_fallocate(struct file *file, int mode,
 	if (mode & FALLOC_FL_PUNCH_HOLE)
 		return btrfs_punch_hole(file, offset, len);
 
-	/*
-	 * Only trigger disk allocation, don't trigger qgroup reserve
-	 *
-	 * For qgroup space, it will be checked later.
-	 */
-	if (!(mode & FALLOC_FL_ZERO_RANGE)) {
-		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
-						      alloc_end - alloc_start);
-		if (ret < 0)
-			return ret;
-	}
-
 	btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
 
 	if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
@@ -3485,8 +3481,12 @@ static long btrfs_fallocate(struct file *file, int mode,
 	}
 
 	/*
-	 * wait for ordered IO before we have any locks.  We'll loop again
-	 * below with the locks held.
+	 * We have locked the inode at the VFS level (in exclusive mode) and we
+	 * have locked the i_mmap_lock lock (in exclusive mode). Now before
+	 * locking the file range, flush all dealloc in the range and wait for
+	 * all ordered extents in the range to complete. After this we can lock
+	 * the file range and, due to the previous locking we did, we know there
+	 * can't be more delalloc or ordered extents in the range.
 	 */
 	ret = btrfs_wait_ordered_range(inode, alloc_start,
 				       alloc_end - alloc_start);
@@ -3500,38 +3500,10 @@ static long btrfs_fallocate(struct file *file, int mode,
 	}
 
 	locked_end = alloc_end - 1;
-	while (1) {
-		struct btrfs_ordered_extent *ordered;
+	lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
+			 &cached_state);
 
-		/* the extent lock is ordered inside the running
-		 * transaction
-		 */
-		lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
-				 locked_end, &cached_state);
-		ordered = btrfs_lookup_first_ordered_extent(BTRFS_I(inode),
-							    locked_end);
-
-		if (ordered &&
-		    ordered->file_offset + ordered->num_bytes > alloc_start &&
-		    ordered->file_offset < alloc_end) {
-			btrfs_put_ordered_extent(ordered);
-			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
-					     alloc_start, locked_end,
-					     &cached_state);
-			/*
-			 * we can't wait on the range with the transaction
-			 * running or with the extent lock held
-			 */
-			ret = btrfs_wait_ordered_range(inode, alloc_start,
-						       alloc_end - alloc_start);
-			if (ret)
-				goto out;
-		} else {
-			if (ordered)
-				btrfs_put_ordered_extent(ordered);
-			break;
-		}
-	}
+	btrfs_assert_inode_range_clean(BTRFS_I(inode), alloc_start, locked_end);
 
 	/* First, check if we exceed the qgroup limit */
 	INIT_LIST_HEAD(&reserve_list);
@@ -3548,48 +3520,64 @@ static long btrfs_fallocate(struct file *file, int mode,
 		if (em->block_start == EXTENT_MAP_HOLE ||
 		    (cur_offset >= inode->i_size &&
 		     !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
-			ret = add_falloc_range(&reserve_list, cur_offset,
-					       last_byte - cur_offset);
+			const u64 range_len = last_byte - cur_offset;
+
+			ret = add_falloc_range(&reserve_list, cur_offset, range_len);
 			if (ret < 0) {
 				free_extent_map(em);
 				break;
 			}
 			ret = btrfs_qgroup_reserve_data(BTRFS_I(inode),
-					&data_reserved, cur_offset,
-					last_byte - cur_offset);
+					&data_reserved, cur_offset, range_len);
 			if (ret < 0) {
-				cur_offset = last_byte;
 				free_extent_map(em);
 				break;
 			}
-		} else {
-			/*
-			 * Do not need to reserve unwritten extent for this
-			 * range, free reserved data space first, otherwise
-			 * it'll result in false ENOSPC error.
-			 */
-			btrfs_free_reserved_data_space(BTRFS_I(inode),
-				data_reserved, cur_offset,
-				last_byte - cur_offset);
+			qgroup_reserved += range_len;
+			data_space_needed += range_len;
 		}
 		free_extent_map(em);
 		cur_offset = last_byte;
 	}
 
+	if (!ret && data_space_needed > 0) {
+		/*
+		 * We are safe to reserve space here as we can't have delalloc
+		 * in the range, see above.
+		 */
+		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
+						      data_space_needed);
+		if (!ret)
+			data_space_reserved = data_space_needed;
+	}
+
 	/*
 	 * If ret is still 0, means we're OK to fallocate.
 	 * Or just cleanup the list and exit.
 	 */
 	list_for_each_entry_safe(range, tmp, &reserve_list, list) {
-		if (!ret)
+		if (!ret) {
 			ret = btrfs_prealloc_file_range(inode, mode,
 					range->start,
 					range->len, i_blocksize(inode),
 					offset + len, &alloc_hint);
-		else
+			/*
+			 * btrfs_prealloc_file_range() releases space even
+			 * if it returns an error.
+			 */
+			data_space_reserved -= range->len;
+			qgroup_reserved -= range->len;
+		} else if (data_space_reserved > 0) {
 			btrfs_free_reserved_data_space(BTRFS_I(inode),
-					data_reserved, range->start,
-					range->len);
+					       data_reserved, range->start,
+					       range->len);
+			data_space_reserved -= range->len;
+			qgroup_reserved -= range->len;
+		} else if (qgroup_reserved > 0) {
+			btrfs_qgroup_free_data(BTRFS_I(inode), data_reserved,
+					       range->start, range->len);
+			qgroup_reserved -= range->len;
+		}
 		list_del(&range->list);
 		kfree(range);
 	}
@@ -3606,10 +3594,6 @@ out_unlock:
 			     &cached_state);
 out:
 	btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
-	/* Let go of our reservation. */
-	if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
-		btrfs_free_reserved_data_space(BTRFS_I(inode), data_reserved,
-				cur_offset, alloc_end - cur_offset);
 	extent_changeset_free(data_reserved);
 	return ret;
 }
@@ -3767,8 +3751,7 @@ again:
 	 */
 	pagefault_disable();
 	to->nofault = true;
-	ret = iomap_dio_rw(iocb, to, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
-			   IOMAP_DIO_PARTIAL, read);
+	ret = btrfs_dio_rw(iocb, to, read);
 	to->nofault = false;
 	pagefault_enable();