diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 8cc58ae6494f..30538c200fdb 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1363,11 +1363,6 @@ static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
 		f2fs_invalidate_compress_page(sbi, old_blkaddr);
 	}
 	f2fs_update_data_blkaddr(dn, dn->data_blkaddr);
-
-	/*
-	 * i_size will be updated by direct_IO. Otherwise, we'll get stale
-	 * data from unwritten block via dio_read.
-	 */
 	return 0;
 }
 
@@ -1655,47 +1650,6 @@ static inline u64 blks_to_bytes(struct inode *inode, u64 blks)
 	return (blks << inode->i_blkbits);
 }
 
-static int __get_data_block(struct inode *inode, sector_t iblock,
-			struct buffer_head *bh, int create, int flag,
-			pgoff_t *next_pgofs, int seg_type, bool may_write)
-{
-	struct f2fs_map_blocks map;
-	int err;
-
-	map.m_lblk = iblock;
-	map.m_len = bytes_to_blks(inode, bh->b_size);
-	map.m_next_pgofs = next_pgofs;
-	map.m_next_extent = NULL;
-	map.m_seg_type = seg_type;
-	map.m_may_create = may_write;
-
-	err = f2fs_map_blocks(inode, &map, create, flag);
-	if (!err) {
-		map_bh(bh, inode->i_sb, map.m_pblk);
-		bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
-		bh->b_size = blks_to_bytes(inode, map.m_len);
-	}
-	return err;
-}
-
-static int get_data_block_dio_write(struct inode *inode, sector_t iblock,
-			struct buffer_head *bh_result, int create)
-{
-	return __get_data_block(inode, iblock, bh_result, create,
-				F2FS_GET_BLOCK_DIO, NULL,
-				f2fs_rw_hint_to_seg_type(inode->i_write_hint),
-				true);
-}
-
-static int get_data_block_dio(struct inode *inode, sector_t iblock,
-			struct buffer_head *bh_result, int create)
-{
-	return __get_data_block(inode, iblock, bh_result, create,
-				F2FS_GET_BLOCK_DIO, NULL,
-				f2fs_rw_hint_to_seg_type(inode->i_write_hint),
-				false);
-}
-
 static int f2fs_xattr_fiemap(struct inode *inode,
 				struct fiemap_extent_info *fieinfo)
 {
@@ -3132,7 +3086,7 @@ static int f2fs_write_data_pages(struct address_space *mapping,
 			FS_CP_DATA_IO : FS_DATA_IO);
 }
 
-static void f2fs_write_failed(struct inode *inode, loff_t to)
+void f2fs_write_failed(struct inode *inode, loff_t to)
 {
 	loff_t i_size = i_size_read(inode);
 
@@ -3417,158 +3371,6 @@ static int f2fs_write_end(struct file *file,
 	return copied;
 }
 
-static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
-			   loff_t offset)
-{
-	unsigned i_blkbits = READ_ONCE(inode->i_blkbits);
-	unsigned blkbits = i_blkbits;
-	unsigned blocksize_mask = (1 << blkbits) - 1;
-	unsigned long align = offset | iov_iter_alignment(iter);
-	struct block_device *bdev = inode->i_sb->s_bdev;
-
-	if (iov_iter_rw(iter) == READ && offset >= i_size_read(inode))
-		return 1;
-
-	if (align & blocksize_mask) {
-		if (bdev)
-			blkbits = blksize_bits(bdev_logical_block_size(bdev));
-		blocksize_mask = (1 << blkbits) - 1;
-		if (align & blocksize_mask)
-			return -EINVAL;
-		return 1;
-	}
-	return 0;
-}
-
-static void f2fs_dio_end_io(struct bio *bio)
-{
-	struct f2fs_private_dio *dio = bio->bi_private;
-
-	dec_page_count(F2FS_I_SB(dio->inode),
-			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
-
-	bio->bi_private = dio->orig_private;
-	bio->bi_end_io = dio->orig_end_io;
-
-	kfree(dio);
-
-	bio_endio(bio);
-}
-
-static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
-							loff_t file_offset)
-{
-	struct f2fs_private_dio *dio;
-	bool write = (bio_op(bio) == REQ_OP_WRITE);
-
-	dio = f2fs_kzalloc(F2FS_I_SB(inode),
-			sizeof(struct f2fs_private_dio), GFP_NOFS);
-	if (!dio)
-		goto out;
-
-	dio->inode = inode;
-	dio->orig_end_io = bio->bi_end_io;
-	dio->orig_private = bio->bi_private;
-	dio->write = write;
-
-	bio->bi_end_io = f2fs_dio_end_io;
-	bio->bi_private = dio;
-
-	inc_page_count(F2FS_I_SB(inode),
-			write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
-
-	submit_bio(bio);
-	return;
-out:
-	bio->bi_status = BLK_STS_IOERR;
-	bio_endio(bio);
-}
-
-static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
-{
-	struct address_space *mapping = iocb->ki_filp->f_mapping;
-	struct inode *inode = mapping->host;
-	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
-	struct f2fs_inode_info *fi = F2FS_I(inode);
-	size_t count = iov_iter_count(iter);
-	loff_t offset = iocb->ki_pos;
-	int rw = iov_iter_rw(iter);
-	int err;
-	enum rw_hint hint = iocb->ki_hint;
-	int whint_mode = F2FS_OPTION(sbi).whint_mode;
-	bool do_opu;
-
-	err = check_direct_IO(inode, iter, offset);
-	if (err)
-		return err < 0 ? err : 0;
-
-	if (f2fs_force_buffered_io(inode, iocb, iter))
-		return 0;
-
-	do_opu = rw == WRITE && f2fs_lfs_mode(sbi);
-
-	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
-
-	if (rw == WRITE && whint_mode == WHINT_MODE_OFF)
-		iocb->ki_hint = WRITE_LIFE_NOT_SET;
-
-	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!down_read_trylock(&fi->i_gc_rwsem[rw])) {
-			iocb->ki_hint = hint;
-			err = -EAGAIN;
-			goto out;
-		}
-		if (do_opu && !down_read_trylock(&fi->i_gc_rwsem[READ])) {
-			up_read(&fi->i_gc_rwsem[rw]);
-			iocb->ki_hint = hint;
-			err = -EAGAIN;
-			goto out;
-		}
-	} else {
-		down_read(&fi->i_gc_rwsem[rw]);
-		if (do_opu)
-			down_read(&fi->i_gc_rwsem[READ]);
-	}
-
-	err = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
-			iter, rw == WRITE ? get_data_block_dio_write :
-			get_data_block_dio, NULL, f2fs_dio_submit_bio,
-			rw == WRITE ? DIO_LOCKING | DIO_SKIP_HOLES :
-			DIO_SKIP_HOLES);
-
-	if (do_opu)
-		up_read(&fi->i_gc_rwsem[READ]);
-
-	up_read(&fi->i_gc_rwsem[rw]);
-
-	if (rw == WRITE) {
-		if (whint_mode == WHINT_MODE_OFF)
-			iocb->ki_hint = hint;
-		if (err > 0) {
-			f2fs_update_iostat(F2FS_I_SB(inode), APP_DIRECT_IO,
-									err);
-			if (!do_opu)
-				set_inode_flag(inode, FI_UPDATE_WRITE);
-		} else if (err == -EIOCBQUEUED) {
-			f2fs_update_iostat(F2FS_I_SB(inode), APP_DIRECT_IO,
-						count - iov_iter_count(iter));
-		} else if (err < 0) {
-			f2fs_write_failed(inode, offset + count);
-		}
-	} else {
-		if (err > 0)
-			f2fs_update_iostat(sbi, APP_DIRECT_READ_IO, err);
-		else if (err == -EIOCBQUEUED)
-			f2fs_update_iostat(F2FS_I_SB(inode), APP_DIRECT_READ_IO,
-						count - iov_iter_count(iter));
-	}
-
-out:
-	trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
-
-	return err;
-}
-
 void f2fs_invalidate_page(struct page *page, unsigned int offset,
 							unsigned int length)
 {
@@ -4024,7 +3826,7 @@ const struct address_space_operations f2fs_dblock_aops = {
 	.set_page_dirty	= f2fs_set_data_page_dirty,
 	.invalidatepage	= f2fs_invalidate_page,
 	.releasepage	= f2fs_release_page,
-	.direct_IO	= f2fs_direct_IO,
+	.direct_IO	= noop_direct_IO,
 	.bmap		= f2fs_bmap,
 	.swap_activate  = f2fs_swap_activate,
 	.swap_deactivate = f2fs_swap_deactivate,
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 231e3bf2a63e..64ba70e7b738 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1755,13 +1755,6 @@ struct f2fs_sb_info {
 #endif
 };
 
-struct f2fs_private_dio {
-	struct inode *inode;
-	void *orig_private;
-	bio_end_io_t *orig_end_io;
-	bool write;
-};
-
 #ifdef CONFIG_F2FS_FAULT_INJECTION
 #define f2fs_show_injection_info(sbi, type)					\
 	printk_ratelimited("%sF2FS-fs (%s) : inject %s in %s of %pS\n",	\
@@ -3243,15 +3236,12 @@ static inline void f2fs_update_iostat(struct f2fs_sb_info *sbi,
 	spin_lock(&sbi->iostat_lock);
 	sbi->rw_iostat[type] += io_bytes;
 
-	if (type == APP_WRITE_IO || type == APP_DIRECT_IO)
-		sbi->rw_iostat[APP_BUFFERED_IO] =
-			sbi->rw_iostat[APP_WRITE_IO] -
-			sbi->rw_iostat[APP_DIRECT_IO];
+	if (type == APP_BUFFERED_IO || type == APP_DIRECT_IO)
+		sbi->rw_iostat[APP_WRITE_IO] += io_bytes;
+
+	if (type == APP_BUFFERED_READ_IO || type == APP_DIRECT_READ_IO)
+		sbi->rw_iostat[APP_READ_IO] += io_bytes;
 
-	if (type == APP_READ_IO || type == APP_DIRECT_READ_IO)
-		sbi->rw_iostat[APP_BUFFERED_READ_IO] =
-			sbi->rw_iostat[APP_READ_IO] -
-			sbi->rw_iostat[APP_DIRECT_READ_IO];
 	spin_unlock(&sbi->iostat_lock);
 
 	f2fs_record_iostat(sbi);
@@ -3631,6 +3621,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 				struct writeback_control *wbc,
 				enum iostat_type io_type,
 				int compr_blocks, bool allow_balance);
+void f2fs_write_failed(struct inode *inode, loff_t to);
 void f2fs_invalidate_page(struct page *page, unsigned int offset,
 			unsigned int length);
 int f2fs_release_page(struct page *page, gfp_t wait);
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 279252c7f7bc..33f6520e1056 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -23,6 +23,7 @@
 #include <linux/nls.h>
 #include <linux/sched/signal.h>
 #include <linux/fileattr.h>
+#include <linux/iomap.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -4201,23 +4202,145 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	return __f2fs_ioctl(filp, cmd, arg);
 }
 
-static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+/*
+ * Return %true if the given read or write request should use direct I/O, or
+ * %false if it should use buffered I/O.
+ */
+static bool f2fs_should_use_dio(struct inode *inode, struct kiocb *iocb,
+				struct iov_iter *iter)
+{
+	unsigned int align;
+
+	if (!(iocb->ki_flags & IOCB_DIRECT))
+		return false;
+
+	if (f2fs_force_buffered_io(inode, iocb, iter))
+		return false;
+
+	/*
+	 * Direct I/O not aligned to the disk's logical_block_size will be
+	 * attempted, but will fail with -EINVAL.
+	 *
+	 * f2fs additionally requires that direct I/O be aligned to the
+	 * filesystem block size, which is often a stricter requirement.
+	 * However, f2fs traditionally falls back to buffered I/O on requests
+	 * that are logical_block_size-aligned but not fs-block aligned.
+	 *
+	 * The below logic implements this behavior.
+	 */
+	align = iocb->ki_pos | iov_iter_alignment(iter);
+	if (!IS_ALIGNED(align, i_blocksize(inode)) &&
+	    IS_ALIGNED(align, bdev_logical_block_size(inode->i_sb->s_bdev)))
+		return false;
+
+	return true;
+}
+
+static int f2fs_dio_read_end_io(struct kiocb *iocb, ssize_t size, int error,
+				unsigned int flags)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(iocb->ki_filp));
+
+	dec_page_count(sbi, F2FS_DIO_READ);
+	if (error)
+		return error;
+	f2fs_update_iostat(sbi, APP_DIRECT_READ_IO, size);
+	return 0;
+}
+
+static const struct iomap_dio_ops f2fs_iomap_dio_read_ops = {
+	.end_io = f2fs_dio_read_end_io,
+};
+
+static ssize_t f2fs_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
-	int ret;
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	const loff_t pos = iocb->ki_pos;
+	const size_t count = iov_iter_count(to);
+	struct iomap_dio *dio;
+	ssize_t ret;
+
+	if (count == 0)
+		return 0; /* skip atime update */
+
+	trace_f2fs_direct_IO_enter(inode, pos, count, READ);
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		if (!down_read_trylock(&fi->i_gc_rwsem[READ])) {
+			ret = -EAGAIN;
+			goto out;
+		}
+	} else {
+		down_read(&fi->i_gc_rwsem[READ]);
+	}
+
+	/*
+	 * We have to use __iomap_dio_rw() and iomap_dio_complete() instead of
+	 * the higher-level function iomap_dio_rw() in order to ensure that the
+	 * F2FS_DIO_READ counter will be decremented correctly in all cases.
+	 */
+	inc_page_count(sbi, F2FS_DIO_READ);
+	dio = __iomap_dio_rw(iocb, to, &f2fs_iomap_ops,
+			     &f2fs_iomap_dio_read_ops, 0);
+	if (IS_ERR_OR_NULL(dio)) {
+		ret = PTR_ERR_OR_ZERO(dio);
+		if (ret != -EIOCBQUEUED)
+			dec_page_count(sbi, F2FS_DIO_READ);
+	} else {
+		ret = iomap_dio_complete(dio);
+	}
+
+	up_read(&fi->i_gc_rwsem[READ]);
+
+	file_accessed(file);
+out:
+	trace_f2fs_direct_IO_exit(inode, pos, count, READ, ret);
+	return ret;
+}
+
+static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
 
 	if (!f2fs_is_compress_backend_ready(inode))
 		return -EOPNOTSUPP;
 
-	ret = generic_file_read_iter(iocb, iter);
+	if (f2fs_should_use_dio(inode, iocb, to))
+		return f2fs_dio_read_iter(iocb, to);
 
+	ret = filemap_read(iocb, to, 0);
 	if (ret > 0)
-		f2fs_update_iostat(F2FS_I_SB(inode), APP_READ_IO, ret);
-
+		f2fs_update_iostat(F2FS_I_SB(inode), APP_BUFFERED_READ_IO, ret);
 	return ret;
 }
 
+static ssize_t f2fs_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	ssize_t count;
+	int err;
+
+	if (IS_IMMUTABLE(inode))
+		return -EPERM;
+
+	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED))
+		return -EPERM;
+
+	count = generic_write_checks(iocb, from);
+	if (count <= 0)
+		return count;
+
+	err = file_modified(file);
+	if (err)
+		return err;
+	return count;
+}
+
 /*
  * Preallocate blocks for a write request, if it is possible and helpful to do
  * so.  Returns a positive number if blocks may have been preallocated, 0 if no
@@ -4225,15 +4348,14 @@ static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
  * seriously wrong.  Also sets FI_PREALLOCATED_ALL on the inode if *all* the
  * requested blocks (not just some of them) have been allocated.
  */
-static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter)
+static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
+				   bool dio)
 {
 	struct inode *inode = file_inode(iocb->ki_filp);
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	const loff_t pos = iocb->ki_pos;
 	const size_t count = iov_iter_count(iter);
 	struct f2fs_map_blocks map = {};
-	bool dio = (iocb->ki_flags & IOCB_DIRECT) &&
-		   !f2fs_force_buffered_io(inode, iocb, iter);
 	int flag;
 	int ret;
 
@@ -4278,13 +4400,174 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter)
 	return map.m_len;
 }
 
-static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+static ssize_t f2fs_buffered_write_iter(struct kiocb *iocb,
+					struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
+	ssize_t ret;
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		return -EOPNOTSUPP;
+
+	current->backing_dev_info = inode_to_bdi(inode);
+	ret = generic_perform_write(file, from, iocb->ki_pos);
+	current->backing_dev_info = NULL;
+
+	if (ret > 0) {
+		iocb->ki_pos += ret;
+		f2fs_update_iostat(F2FS_I_SB(inode), APP_BUFFERED_IO, ret);
+	}
+	return ret;
+}
+
+static int f2fs_dio_write_end_io(struct kiocb *iocb, ssize_t size, int error,
+				 unsigned int flags)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(iocb->ki_filp));
+
+	dec_page_count(sbi, F2FS_DIO_WRITE);
+	if (error)
+		return error;
+	f2fs_update_iostat(sbi, APP_DIRECT_IO, size);
+	return 0;
+}
+
+static const struct iomap_dio_ops f2fs_iomap_dio_write_ops = {
+	.end_io = f2fs_dio_write_end_io,
+};
+
+static ssize_t f2fs_dio_write_iter(struct kiocb *iocb, struct iov_iter *from,
+				   bool *may_need_sync)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct f2fs_inode_info *fi = F2FS_I(inode);
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	const bool do_opu = f2fs_lfs_mode(sbi);
+	const int whint_mode = F2FS_OPTION(sbi).whint_mode;
+	const loff_t pos = iocb->ki_pos;
+	const ssize_t count = iov_iter_count(from);
+	const enum rw_hint hint = iocb->ki_hint;
+	unsigned int dio_flags;
+	struct iomap_dio *dio;
+	ssize_t ret;
+
+	trace_f2fs_direct_IO_enter(inode, pos, count, WRITE);
+
+	if (iocb->ki_flags & IOCB_NOWAIT) {
+		/* f2fs_convert_inline_inode() and block allocation can block */
+		if (f2fs_has_inline_data(inode) ||
+		    !f2fs_overwrite_io(inode, pos, count)) {
+			ret = -EAGAIN;
+			goto out;
+		}
+
+		if (!down_read_trylock(&fi->i_gc_rwsem[WRITE])) {
+			ret = -EAGAIN;
+			goto out;
+		}
+		if (do_opu && !down_read_trylock(&fi->i_gc_rwsem[READ])) {
+			up_read(&fi->i_gc_rwsem[WRITE]);
+			ret = -EAGAIN;
+			goto out;
+		}
+	} else {
+		ret = f2fs_convert_inline_inode(inode);
+		if (ret)
+			goto out;
+
+		down_read(&fi->i_gc_rwsem[WRITE]);
+		if (do_opu)
+			down_read(&fi->i_gc_rwsem[READ]);
+	}
+	if (whint_mode == WHINT_MODE_OFF)
+		iocb->ki_hint = WRITE_LIFE_NOT_SET;
+
+	/*
+	 * We have to use __iomap_dio_rw() and iomap_dio_complete() instead of
+	 * the higher-level function iomap_dio_rw() in order to ensure that the
+	 * F2FS_DIO_WRITE counter will be decremented correctly in all cases.
+	 */
+	inc_page_count(sbi, F2FS_DIO_WRITE);
+	dio_flags = 0;
+	if (pos + count > inode->i_size)
+		dio_flags |= IOMAP_DIO_FORCE_WAIT;
+	dio = __iomap_dio_rw(iocb, from, &f2fs_iomap_ops,
+			     &f2fs_iomap_dio_write_ops, dio_flags);
+	if (IS_ERR_OR_NULL(dio)) {
+		ret = PTR_ERR_OR_ZERO(dio);
+		if (ret == -ENOTBLK)
+			ret = 0;
+		if (ret != -EIOCBQUEUED)
+			dec_page_count(sbi, F2FS_DIO_WRITE);
+	} else {
+		ret = iomap_dio_complete(dio);
+	}
+
+	if (whint_mode == WHINT_MODE_OFF)
+		iocb->ki_hint = hint;
+	if (do_opu)
+		up_read(&fi->i_gc_rwsem[READ]);
+	up_read(&fi->i_gc_rwsem[WRITE]);
+
+	if (ret < 0)
+		goto out;
+	if (pos + ret > inode->i_size)
+		f2fs_i_size_write(inode, pos + ret);
+	if (!do_opu)
+		set_inode_flag(inode, FI_UPDATE_WRITE);
+
+	if (iov_iter_count(from)) {
+		ssize_t ret2;
+		loff_t bufio_start_pos = iocb->ki_pos;
+
+		/*
+		 * The direct write was partial, so we need to fall back to a
+		 * buffered write for the remainder.
+		 */
+
+		ret2 = f2fs_buffered_write_iter(iocb, from);
+		if (iov_iter_count(from))
+			f2fs_write_failed(inode, iocb->ki_pos);
+		if (ret2 < 0)
+			goto out;
+
+		/*
+		 * Ensure that the pagecache pages are written to disk and
+		 * invalidated to preserve the expected O_DIRECT semantics.
+		 */
+		if (ret2 > 0) {
+			loff_t bufio_end_pos = bufio_start_pos + ret2 - 1;
+
+			ret += ret2;
+
+			ret2 = filemap_write_and_wait_range(file->f_mapping,
+							    bufio_start_pos,
+							    bufio_end_pos);
+			if (ret2 < 0)
+				goto out;
+			invalidate_mapping_pages(file->f_mapping,
+						 bufio_start_pos >> PAGE_SHIFT,
+						 bufio_end_pos >> PAGE_SHIFT);
+		}
+	} else {
+		/* iomap_dio_rw() already handled the generic_write_sync(). */
+		*may_need_sync = false;
+	}
+out:
+	trace_f2fs_direct_IO_exit(inode, pos, count, WRITE, ret);
+	return ret;
+}
+
+static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
 	const loff_t orig_pos = iocb->ki_pos;
 	const size_t orig_count = iov_iter_count(from);
 	loff_t target_size;
+	bool dio;
+	bool may_need_sync = true;
 	int preallocated;
 	ssize_t ret;
 
@@ -4307,48 +4590,26 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		inode_lock(inode);
 	}
 
-	if (unlikely(IS_IMMUTABLE(inode))) {
-		ret = -EPERM;
-		goto out_unlock;
-	}
-
-	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
-		ret = -EPERM;
-		goto out_unlock;
-	}
-
-	ret = generic_write_checks(iocb, from);
+	ret = f2fs_write_checks(iocb, from);
 	if (ret <= 0)
 		goto out_unlock;
 
-	if (iocb->ki_flags & IOCB_NOWAIT) {
-		if (!f2fs_overwrite_io(inode, iocb->ki_pos,
-				       iov_iter_count(from)) ||
-		    f2fs_has_inline_data(inode) ||
-		    f2fs_force_buffered_io(inode, iocb, from)) {
-			ret = -EAGAIN;
-			goto out_unlock;
-		}
-	}
-	if (iocb->ki_flags & IOCB_DIRECT) {
-		/*
-		 * Convert inline data for Direct I/O before entering
-		 * f2fs_direct_IO().
-		 */
-		ret = f2fs_convert_inline_inode(inode);
-		if (ret)
-			goto out_unlock;
-	}
+	/* Determine whether we will do a direct write or a buffered write. */
+	dio = f2fs_should_use_dio(inode, iocb, from);
 
 	/* Possibly preallocate the blocks for the write. */
 	target_size = iocb->ki_pos + iov_iter_count(from);
-	preallocated = f2fs_preallocate_blocks(iocb, from);
+	preallocated = f2fs_preallocate_blocks(iocb, from, dio);
 	if (preallocated < 0) {
 		ret = preallocated;
 		goto out_unlock;
 	}
 
-	ret = __generic_file_write_iter(iocb, from);
+	/* Do the actual write. */
+	if (dio)
+		ret = f2fs_dio_write_iter(iocb, from, &may_need_sync);
+	else
+		ret = f2fs_buffered_write_iter(iocb, from);
 
 	/* Don't leave any preallocated blocks around past i_size. */
 	if (preallocated > 0 && inode->i_size < target_size) {
@@ -4359,14 +4620,11 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
 	}
 	clear_inode_flag(inode, FI_PREALLOCATED_ALL);
-
-	if (ret > 0)
-		f2fs_update_iostat(F2FS_I_SB(inode), APP_WRITE_IO, ret);
 out_unlock:
 	inode_unlock(inode);
 out:
 	trace_f2fs_file_write_iter(inode, orig_pos, orig_count, ret);
-	if (ret > 0)
+	if (ret > 0 && may_need_sync)
 		ret = generic_write_sync(iocb, ret);
 	return ret;
 }
