6 files changed, 284 insertions, 234 deletions

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 68b95ad82126..575636f6491e 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -14,7 +14,6 @@ config BTRFS_FS
 	select LZO_DECOMPRESS
 	select ZSTD_COMPRESS
 	select ZSTD_DECOMPRESS
-	select FS_IOMAP
 	select RAID6_PQ
 	select XOR_BLOCKS
 	select SRCU
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index aeff56a0e105..e7d709505cb1 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -28,6 +28,7 @@ enum {
 	BTRFS_INODE_NEEDS_FULL_SYNC,
 	BTRFS_INODE_COPY_EVERYTHING,
 	BTRFS_INODE_IN_DELALLOC_LIST,
+	BTRFS_INODE_READDIO_NEED_LOCK,
 	BTRFS_INODE_HAS_PROPS,
 	BTRFS_INODE_SNAPSHOT_FLUSH,
 };
@@ -312,6 +313,23 @@ struct btrfs_dio_private {
 	u8 csums[];
 };
 
+/*
+ * Disable DIO read nolock optimization, so new dio readers will be forced
+ * to grab i_mutex. It is used to avoid the endless truncate due to
+ * nonlocked dio read.
+ */
+static inline void btrfs_inode_block_unlocked_dio(struct btrfs_inode *inode)
+{
+	set_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
+	smp_mb();
+}
+
+static inline void btrfs_inode_resume_unlocked_dio(struct btrfs_inode *inode)
+{
+	smp_mb__before_atomic();
+	clear_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
+}
+
 /* Array of bytes with variable length, hexadecimal format 0x1234 */
 #define CSUM_FMT				"0x%*phN"
 #define CSUM_FMT_VALUE(size, bytes)		size, bytes
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 161533040978..30ce7039bc27 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -28,7 +28,6 @@
 #include <linux/dynamic_debug.h>
 #include <linux/refcount.h>
 #include <linux/crc32c.h>
-#include <linux/iomap.h>
 #include "extent-io-tree.h"
 #include "extent_io.h"
 #include "extent_map.h"
@@ -2934,9 +2933,6 @@ int btrfs_writepage_cow_fixup(struct page *page, u64 start, u64 end);
 void btrfs_writepage_endio_finish_ordered(struct page *page, u64 start,
 					  u64 end, int uptodate);
 extern const struct dentry_operations btrfs_dentry_operations;
-ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
-extern const struct iomap_ops btrfs_dio_iomap_ops;
-extern const struct iomap_dio_ops btrfs_dops;
 
 /* ioctl.c */
 long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index fde125616687..2c14312b05e8 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1809,61 +1809,21 @@ again:
 	return num_written ? num_written : ret;
 }
 
-static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
-                               const struct iov_iter *iter, loff_t offset)
-{
-        const unsigned int blocksize_mask = fs_info->sectorsize - 1;
-
-        if (offset & blocksize_mask)
-                return -EINVAL;
-
-        if (iov_iter_alignment(iter) & blocksize_mask)
-                return -EINVAL;
-
-	return 0;
-}
-
-static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
+static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
-	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-	loff_t pos = iocb->ki_pos;
-	ssize_t written = 0;
+	loff_t pos;
+	ssize_t written;
 	ssize_t written_buffered;
 	loff_t endbyte;
 	int err;
-	size_t count = 0;
-	bool relock = false;
 
-	if (check_direct_IO(fs_info, from, pos))
-		goto buffered;
-
-	count = iov_iter_count(from);
-	/*
-	 * If the write DIO is beyond the EOF, we need update the isize, but it
-	 * is protected by i_mutex. So we can not unlock the i_mutex at this
-	 * case.
-	 */
-	if (pos + count <= inode->i_size) {
-		inode_unlock(inode);
-		relock = true;
-	} else if (iocb->ki_flags & IOCB_NOWAIT) {
-		return -EAGAIN;
-	}
-
-	down_read(&BTRFS_I(inode)->dio_sem);
-	written = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops, &btrfs_dops,
-			       is_sync_kiocb(iocb));
-	up_read(&BTRFS_I(inode)->dio_sem);
-
-	if (relock)
-		inode_lock(inode);
+	written = generic_file_direct_write(iocb, from);
 
 	if (written < 0 || !iov_iter_count(from))
 		return written;
 
-buffered:
 	pos = iocb->ki_pos;
 	written_buffered = btrfs_buffered_write(iocb, from);
 	if (written_buffered < 0) {
@@ -2002,7 +1962,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 		atomic_inc(&BTRFS_I(inode)->sync_writers);
 
 	if (iocb->ki_flags & IOCB_DIRECT) {
-		num_written = btrfs_direct_write(iocb, from);
+		num_written = __btrfs_direct_write(iocb, from);
 	} else {
 		num_written = btrfs_buffered_write(iocb, from);
 		if (num_written > 0)
@@ -3516,54 +3476,9 @@ static int btrfs_file_open(struct inode *inode, struct file *filp)
 	return generic_file_open(inode, filp);
 }
 
-static int check_direct_read(struct btrfs_fs_info *fs_info,
-                               const struct iov_iter *iter, loff_t offset)
-{
-	int ret;
-	int i, seg;
-
-	ret = check_direct_IO(fs_info, iter, offset);
-	if (ret < 0)
-		return ret;
-
-	for (seg = 0; seg < iter->nr_segs; seg++)
-		for (i = seg + 1; i < iter->nr_segs; i++)
-			if (iter->iov[seg].iov_base == iter->iov[i].iov_base)
-				return -EINVAL;
-	return 0;
-}
-
-static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to)
-{
-	struct inode *inode = file_inode(iocb->ki_filp);
-	ssize_t ret;
-
-	if (check_direct_read(btrfs_sb(inode->i_sb), to, iocb->ki_pos))
-		return 0;
-
-	inode_lock_shared(inode);
-        ret = iomap_dio_rw(iocb, to, &btrfs_dio_iomap_ops, &btrfs_dops,
-			   is_sync_kiocb(iocb));
-	inode_unlock_shared(inode);
-	return ret;
-}
-
-static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
-	ssize_t ret = 0;
-
-	if (iocb->ki_flags & IOCB_DIRECT) {
-		ret = btrfs_direct_read(iocb, to);
-		if (ret < 0)
-			return ret;
-	}
-
-	return generic_file_buffered_read(iocb, to, ret);
-}
-
 const struct file_operations btrfs_file_operations = {
 	.llseek		= btrfs_file_llseek,
-	.read_iter      = btrfs_file_read_iter,
+	.read_iter      = generic_file_read_iter,
 	.splice_read	= generic_file_splice_read,
 	.write_iter	= btrfs_file_write_iter,
 	.mmap		= btrfs_file_mmap,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 31ac8c682f19..d04c82c88418 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5,6 +5,7 @@
 
 #include <linux/kernel.h>
 #include <linux/bio.h>
+#include <linux/buffer_head.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
@@ -57,9 +58,9 @@ struct btrfs_iget_args {
 
 struct btrfs_dio_data {
 	u64 reserve;
-	loff_t length;
-	ssize_t submitted;
-	struct extent_changeset *data_reserved;
+	u64 unsubmitted_oe_range_start;
+	u64 unsubmitted_oe_range_end;
+	int overwrite;
 };
 
 static const struct inode_operations btrfs_dir_inode_operations;
@@ -4810,7 +4811,10 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
 
 		truncate_setsize(inode, newsize);
 
+		/* Disable nonlocked read DIO to avoid the endless truncate */
+		btrfs_inode_block_unlocked_dio(BTRFS_I(inode));
 		inode_dio_wait(inode);
+		btrfs_inode_resume_unlocked_dio(BTRFS_I(inode));
 
 		ret = btrfs_truncate(inode, newsize == oldsize);
 		if (ret && inode->i_nlink) {
@@ -7041,7 +7045,7 @@ out:
 }
 
 static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
-			      struct extent_state **cached_state, bool writing)
+			      struct extent_state **cached_state, int writing)
 {
 	struct btrfs_ordered_extent *ordered;
 	int ret = 0;
@@ -7179,7 +7183,30 @@ static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len,
 }
 
 
+static int btrfs_get_blocks_direct_read(struct extent_map *em,
+					struct buffer_head *bh_result,
+					struct inode *inode,
+					u64 start, u64 len)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+
+	if (em->block_start == EXTENT_MAP_HOLE ||
+			test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		return -ENOENT;
+
+	len = min(len, em->len - (start - em->start));
+
+	bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
+		inode->i_blkbits;
+	bh_result->b_size = len;
+	bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
+	set_buffer_mapped(bh_result);
+
+	return 0;
+}
+
 static int btrfs_get_blocks_direct_write(struct extent_map **map,
+					 struct buffer_head *bh_result,
 					 struct inode *inode,
 					 struct btrfs_dio_data *dio_data,
 					 u64 start, u64 len)
@@ -7241,6 +7268,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
 	}
 
 	/* this will cow the extent */
+	len = bh_result->b_size;
 	free_extent_map(em);
 	*map = em = btrfs_new_extent_direct(inode, start, len);
 	if (IS_ERR(em)) {
@@ -7251,73 +7279,64 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
 	len = min(len, em->len - (start - em->start));
 
 skip_cow:
+	bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
+		inode->i_blkbits;
+	bh_result->b_size = len;
+	bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
+	set_buffer_mapped(bh_result);
+
+	if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+		set_buffer_new(bh_result);
+
 	/*
 	 * Need to update the i_size under the extent lock so buffered
 	 * readers will get the updated i_size when we unlock.
 	 */
-	if (start + len > i_size_read(inode))
+	if (!dio_data->overwrite && start + len > i_size_read(inode))
 		i_size_write(inode, start + len);
 
+	WARN_ON(dio_data->reserve < len);
 	dio_data->reserve -= len;
+	dio_data->unsubmitted_oe_range_end = start + len;
+	current->journal_info = dio_data;
 out:
 	return ret;
 }
 
-static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
-		loff_t length, unsigned flags, struct iomap *iomap,
-		struct iomap *srcmap)
+static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
+				   struct buffer_head *bh_result, int create)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct extent_map *em;
 	struct extent_state *cached_state = NULL;
 	struct btrfs_dio_data *dio_data = NULL;
+	u64 start = iblock << inode->i_blkbits;
 	u64 lockstart, lockend;
-	const bool write = !!(flags & IOMAP_WRITE);
+	u64 len = bh_result->b_size;
 	int ret = 0;
-	u64 len = length;
-	bool unlock_extents = false;
 
-	if (!write)
+	if (!create)
 		len = min_t(u64, len, fs_info->sectorsize);
 
 	lockstart = start;
 	lockend = start + len - 1;
 
-	/*
-	 * The generic stuff only does filemap_write_and_wait_range, which
-	 * isn't enough if we've written compressed pages to this area, so we
-	 * need to flush the dirty pages again to make absolutely sure that any
-	 * outstanding dirty pages are on disk.
-	 */
-	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
-		     &BTRFS_I(inode)->runtime_flags))
-		ret = filemap_fdatawrite_range(inode->i_mapping, start,
-					       start + length - 1);
-
-	dio_data = kzalloc(sizeof(*dio_data), GFP_NOFS);
-	if (!dio_data)
-		return -ENOMEM;
-
-	dio_data->length = length;
-	if (write) {
-		dio_data->reserve = round_up(length, fs_info->sectorsize);
-		ret = btrfs_delalloc_reserve_space(inode,
-				&dio_data->data_reserved,
-				start, dio_data->reserve);
-		if (ret) {
-			extent_changeset_free(dio_data->data_reserved);
-			kfree(dio_data);
-			return ret;
-		}
+	if (current->journal_info) {
+		/*
+		 * Need to pull our outstanding extents and set journal_info to NULL so
+		 * that anything that needs to check if there's a transaction doesn't get
+		 * confused.
+		 */
+		dio_data = current->journal_info;
+		current->journal_info = NULL;
 	}
-	iomap->private = dio_data;
-
 
 	/*
 	 * If this errors out it's because we couldn't invalidate pagecache for
 	 * this range and we need to fallback to buffered.
 	 */
-	if (lock_extent_direct(inode, lockstart, lockend, &cached_state, write)) {
+	if (lock_extent_direct(inode, lockstart, lockend, &cached_state,
+			       create)) {
 		ret = -ENOTBLK;
 		goto err;
 	}
@@ -7349,47 +7368,35 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
 		goto unlock_err;
 	}
 
-	len = min(len, em->len - (start - em->start));
-	if (write) {
-		ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
-						    start, len);
+	if (create) {
+		ret = btrfs_get_blocks_direct_write(&em, bh_result, inode,
+						    dio_data, start, len);
 		if (ret < 0)
 			goto unlock_err;
-		unlock_extents = true;
-		/* Recalc len in case the new em is smaller than requested */
-		len = min(len, em->len - (start - em->start));
+
+		unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
+				     lockend, &cached_state);
 	} else {
+		ret = btrfs_get_blocks_direct_read(em, bh_result, inode,
+						   start, len);
+		/* Can be negative only if we read from a hole */
+		if (ret < 0) {
+			ret = 0;
+			free_extent_map(em);
+			goto unlock_err;
+		}
 		/*
 		 * We need to unlock only the end area that we aren't using.
 		 * The rest is going to be unlocked by the endio routine.
 		 */
-		lockstart = start + len;
-		if (lockstart < lockend)
-			unlock_extents = true;
-	}
-
-	if (unlock_extents)
-		unlock_extent_cached(&BTRFS_I(inode)->io_tree,
-				     lockstart, lockend, &cached_state);
-	else
-		free_extent_state(cached_state);
-
-	/*
-	 * Translate extent map information to iomap.
-	 * We trim the extents (and move the addr) even though iomap code does
-	 * that, since we have locked only the parts we are performing I/O in.
-	 */
-	if ((em->block_start == EXTENT_MAP_HOLE) ||
-	    (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) && !write)) {
-		iomap->addr = IOMAP_NULL_ADDR;
-		iomap->type = IOMAP_HOLE;
-	} else {
-		iomap->addr = em->block_start + (start - em->start);
-		iomap->type = IOMAP_MAPPED;
+		lockstart = start + bh_result->b_size;
+		if (lockstart < lockend) {
+			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
+					     lockstart, lockend, &cached_state);
+		} else {
+			free_extent_state(cached_state);
+		}
 	}
-	iomap->offset = start;
-	iomap->bdev = fs_info->fs_devices->latest_bdev;
-	iomap->length = len;
 
 	free_extent_map(em);
 
@@ -7399,53 +7406,8 @@ unlock_err:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
 			     &cached_state);
 err:
-	if (dio_data) {
-		btrfs_delalloc_release_space(inode, dio_data->data_reserved,
-				start, dio_data->reserve, true);
-		btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->reserve);
-		extent_changeset_free(dio_data->data_reserved);
-		kfree(dio_data);
-	}
-	return ret;
-}
-
-static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
-		ssize_t written, unsigned flags, struct iomap *iomap)
-{
-	int ret = 0;
-	struct btrfs_dio_data *dio_data = iomap->private;
-	size_t submitted = dio_data->submitted;
-	const bool write = !!(flags & IOMAP_WRITE);
-
-	if (!write && (iomap->type == IOMAP_HOLE)) {
-		/* If reading from a hole, unlock and return */
-		unlock_extent(&BTRFS_I(inode)->io_tree, pos, pos + length - 1);
-		goto out;
-	}
-
-	if (submitted < length) {
-		pos += submitted;
-		length -= submitted;
-		if (write)
-			__endio_write_update_ordered(inode, pos, length, false);
-		else
-			unlock_extent(&BTRFS_I(inode)->io_tree, pos,
-				      pos + length - 1);
-		ret = -ENOTBLK;
-	}
-
-	if (write) {
-		if (dio_data->reserve)
-			btrfs_delalloc_release_space(inode,
-					dio_data->data_reserved, pos,
-					dio_data->reserve, true);
-		btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->length);
-		extent_changeset_free(dio_data->data_reserved);
-	}
-out:
-	kfree(dio_data);
-	iomap->private = NULL;
-
+	if (dio_data)
+		current->journal_info = dio_data;
 	return ret;
 }
 
@@ -7468,7 +7430,7 @@ static void btrfs_dio_private_put(struct btrfs_dio_private *dip)
 			      dip->logical_offset + dip->bytes - 1);
 	}
 
-	bio_endio(dip->dio_bio);
+	dio_end_io(dip->dio_bio);
 	kfree(dip);
 }
 
@@ -7704,11 +7666,24 @@ static struct btrfs_dio_private *btrfs_create_dio_private(struct bio *dio_bio,
 	dip->disk_bytenr = (u64)dio_bio->bi_iter.bi_sector << 9;
 	dip->dio_bio = dio_bio;
 	refcount_set(&dip->refs, 1);
+
+	if (write) {
+		struct btrfs_dio_data *dio_data = current->journal_info;
+
+		/*
+		 * Setting range start and end to the same value means that
+		 * no cleanup will happen in btrfs_direct_IO
+		 */
+		dio_data->unsubmitted_oe_range_end = dip->logical_offset +
+			dip->bytes;
+		dio_data->unsubmitted_oe_range_start =
+			dio_data->unsubmitted_oe_range_end;
+	}
 	return dip;
 }
 
-static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
-		struct bio *dio_bio, loff_t file_offset)
+static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
+				loff_t file_offset)
 {
 	const bool write = (bio_op(dio_bio) == REQ_OP_WRITE);
 	const bool csum = !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM);
@@ -7725,7 +7700,6 @@ static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
 	int ret;
 	blk_status_t status;
 	struct btrfs_io_geometry geom;
-	struct btrfs_dio_data *dio_data = iomap->private;
 
 	dip = btrfs_create_dio_private(dio_bio, inode, file_offset);
 	if (!dip) {
@@ -7734,8 +7708,8 @@ static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
 				file_offset + dio_bio->bi_iter.bi_size - 1);
 		}
 		dio_bio->bi_status = BLK_STS_RESOURCE;
-		bio_endio(dio_bio);
-		return BLK_QC_T_NONE;
+		dio_end_io(dio_bio);
+		return;
 	}
 
 	if (!write && csum) {
@@ -7806,27 +7780,156 @@ static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
 			goto out_err;
 		}
 
-		dio_data->submitted += clone_len;
 		clone_offset += clone_len;
 		start_sector += clone_len >> 9;
 		file_offset += clone_len;
 	} while (submit_len > 0);
-	return BLK_QC_T_NONE;
+	return;
 
 out_err:
 	dip->dio_bio->bi_status = status;
 	btrfs_dio_private_put(dip);
-	return BLK_QC_T_NONE;
 }
 
-const struct iomap_ops btrfs_dio_iomap_ops = {
-	.iomap_begin            = btrfs_dio_iomap_begin,
-	.iomap_end              = btrfs_dio_iomap_end,
-};
+static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
+			       const struct iov_iter *iter, loff_t offset)
+{
+	int seg;
+	int i;
+	unsigned int blocksize_mask = fs_info->sectorsize - 1;
+	ssize_t retval = -EINVAL;
 
-const struct iomap_dio_ops btrfs_dops = {
-	.submit_io		= btrfs_submit_direct,
-};
+	if (offset & blocksize_mask)
+		goto out;
+
+	if (iov_iter_alignment(iter) & blocksize_mask)
+		goto out;
+
+	/* If this is a write we don't need to check anymore */
+	if (iov_iter_rw(iter) != READ || !iter_is_iovec(iter))
+		return 0;
+	/*
+	 * Check to make sure we don't have duplicate iov_base's in this
+	 * iovec, if so return EINVAL, otherwise we'll get csum errors
+	 * when reading back.
+	 */
+	for (seg = 0; seg < iter->nr_segs; seg++) {
+		for (i = seg + 1; i < iter->nr_segs; i++) {
+			if (iter->iov[seg].iov_base == iter->iov[i].iov_base)
+				goto out;
+		}
+	}
+	retval = 0;
+out:
+	return retval;
+}
+
+static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+	struct btrfs_dio_data dio_data = { 0 };
+	struct extent_changeset *data_reserved = NULL;
+	loff_t offset = iocb->ki_pos;
+	size_t count = 0;
+	int flags = 0;
+	bool wakeup = true;
+	bool relock = false;
+	ssize_t ret;
+
+	if (check_direct_IO(fs_info, iter, offset))
+		return 0;
+
+	inode_dio_begin(inode);
+
+	/*
+	 * The generic stuff only does filemap_write_and_wait_range, which
+	 * isn't enough if we've written compressed pages to this area, so
+	 * we need to flush the dirty pages again to make absolutely sure
+	 * that any outstanding dirty pages are on disk.
+	 */
+	count = iov_iter_count(iter);
+	if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+		     &BTRFS_I(inode)->runtime_flags))
+		filemap_fdatawrite_range(inode->i_mapping, offset,
+					 offset + count - 1);
+
+	if (iov_iter_rw(iter) == WRITE) {
+		/*
+		 * If the write DIO is beyond the EOF, we need update
+		 * the isize, but it is protected by i_mutex. So we can
+		 * not unlock the i_mutex at this case.
+		 */
+		if (offset + count <= inode->i_size) {
+			dio_data.overwrite = 1;
+			inode_unlock(inode);
+			relock = true;
+		} else if (iocb->ki_flags & IOCB_NOWAIT) {
+			ret = -EAGAIN;
+			goto out;
+		}
+		ret = btrfs_delalloc_reserve_space(inode, &data_reserved,
+						   offset, count);
+		if (ret)
+			goto out;
+
+		/*
+		 * We need to know how many extents we reserved so that we can
+		 * do the accounting properly if we go over the number we
+		 * originally calculated.  Abuse current->journal_info for this.
+		 */
+		dio_data.reserve = round_up(count,
+					    fs_info->sectorsize);
+		dio_data.unsubmitted_oe_range_start = (u64)offset;
+		dio_data.unsubmitted_oe_range_end = (u64)offset;
+		current->journal_info = &dio_data;
+		down_read(&BTRFS_I(inode)->dio_sem);
+	} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
+				     &BTRFS_I(inode)->runtime_flags)) {
+		inode_dio_end(inode);
+		flags = DIO_LOCKING | DIO_SKIP_HOLES;
+		wakeup = false;
+	}
+
+	ret = __blockdev_direct_IO(iocb, inode,
+				   fs_info->fs_devices->latest_bdev,
+				   iter, btrfs_get_blocks_direct, NULL,
+				   btrfs_submit_direct, flags);
+	if (iov_iter_rw(iter) == WRITE) {
+		up_read(&BTRFS_I(inode)->dio_sem);
+		current->journal_info = NULL;
+		if (ret < 0 && ret != -EIOCBQUEUED) {
+			if (dio_data.reserve)
+				btrfs_delalloc_release_space(inode, data_reserved,
+					offset, dio_data.reserve, true);
+			/*
+			 * On error we might have left some ordered extents
+			 * without submitting corresponding bios for them, so
+			 * cleanup them up to avoid other tasks getting them
+			 * and waiting for them to complete forever.
+			 */
+			if (dio_data.unsubmitted_oe_range_start <
+			    dio_data.unsubmitted_oe_range_end)
+				__endio_write_update_ordered(inode,
+					dio_data.unsubmitted_oe_range_start,
+					dio_data.unsubmitted_oe_range_end -
+					dio_data.unsubmitted_oe_range_start,
+					false);
+		} else if (ret >= 0 && (size_t)ret < count)
+			btrfs_delalloc_release_space(inode, data_reserved,
+					offset, count - (size_t)ret, true);
+		btrfs_delalloc_release_extents(BTRFS_I(inode), count);
+	}
+out:
+	if (wakeup)
+		inode_dio_end(inode);
+	if (relock)
+		inode_lock(inode);
+
+	extent_changeset_free(data_reserved);
+	return ret;
+}
 
 static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len)
@@ -10122,7 +10225,7 @@ static const struct address_space_operations btrfs_aops = {
 	.writepage	= btrfs_writepage,
 	.writepages	= btrfs_writepages,
 	.readahead	= btrfs_readahead,
-	.direct_IO	= noop_direct_IO,
+	.direct_IO	= btrfs_direct_IO,
 	.invalidatepage = btrfs_invalidatepage,
 	.releasepage	= btrfs_releasepage,
 #ifdef CONFIG_MIGRATION
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 1543b5af400e..6d5370eac2a8 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -386,6 +386,25 @@ static void dio_bio_end_io(struct bio *bio)
 	spin_unlock_irqrestore(&dio->bio_lock, flags);
 }
 
+/**
+ * dio_end_io - handle the end io action for the given bio
+ * @bio: The direct io bio thats being completed
+ *
+ * This is meant to be called by any filesystem that uses their own dio_submit_t
+ * so that the DIO specific endio actions are dealt with after the filesystem
+ * has done it's completion work.
+ */
+void dio_end_io(struct bio *bio)
+{
+	struct dio *dio = bio->bi_private;
+
+	if (dio->is_async)
+		dio_bio_end_aio(bio);
+	else
+		dio_bio_end_io(bio);
+}
+EXPORT_SYMBOL_GPL(dio_end_io);
+
 static inline void
 dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
 	      struct block_device *bdev,