@@ -190,8 +190,8 @@ prototypes:
 	int (*invalidatepage) (struct page *, unsigned long);
 	int (*releasepage) (struct page *, int);
 	void (*freepage)(struct page *);
-	int (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
-			loff_t offset, unsigned long nr_segs);
+	int (*direct_IO)(int, struct kiocb *, struct iov_iter *iter,
+			loff_t offset);
 	int (*get_xip_mem)(struct address_space *, pgoff_t, int, void **,
 				unsigned long *);
 	int (*migratepage)(struct address_space *, struct page *, struct page *);

@@ -569,8 +569,8 @@ struct address_space_operations {
 	int (*invalidatepage) (struct page *, unsigned long);
 	int (*releasepage) (struct page *, int);
 	void (*freepage)(struct page *);
-	ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
-			loff_t offset, unsigned long nr_segs);
+	ssize_t (*direct_IO)(int, struct kiocb *, struct iov_iter *iter,
+			loff_t offset);
 	struct page* (*get_xip_page)(struct address_space *, sector_t,
 			int);
 	/* migrate the contents of a page to the specified target */

@@ -239,9 +239,8 @@ static int v9fs_launder_page(struct page *page)
  * v9fs_direct_IO - 9P address space operation for direct I/O
  * @rw: direction (read or write)
  * @iocb: target I/O control block
- * @iov: array of vectors that define I/O buffer
+ * @iter: array of vectors that define I/O buffer
  * @pos: offset in file to begin the operation
- * @nr_segs: size of iovec array
  *
  * The presence of v9fs_direct_IO() in the address space ops vector
  * allowes open() O_DIRECT flags which would have failed otherwise.

@@ -255,8 +254,7 @@ static int v9fs_launder_page(struct page *page)
  *
  */
 static ssize_t
-v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-	       loff_t pos, unsigned long nr_segs)
+v9fs_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter, loff_t pos)
 {
 	/*
 	 * FIXME

@@ -265,7 +263,7 @@ v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 	 */
 	p9_debug(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) off/no(%lld/%lu) EINVAL\n",
 		 iocb->ki_filp->f_path.dentry->d_name.name,
-		 (long long)pos, nr_segs);
+		 (long long)pos, iter->nr_segs);
 
 	return -EINVAL;
 }

@@ -157,14 +157,14 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
 }
 
 static ssize_t
-blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-			loff_t offset, unsigned long nr_segs)
+blkdev_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
+			loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 
-	return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
-				    nr_segs, blkdev_get_block, NULL, NULL, 0);
+	return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iter,
+				    offset, blkdev_get_block, NULL, NULL, 0);
 }
 
 int __sync_blockdev(struct block_device *bdev, int wait)

@@ -6576,8 +6576,7 @@ free_ordered:
 }
 
 static ssize_t check_direct_IO(struct btrfs_root *root, int rw, struct kiocb *iocb,
-			const struct iovec *iov, loff_t offset,
-			unsigned long nr_segs)
+			struct iov_iter *iter, loff_t offset)
 {
 	int seg;
 	int i;

@@ -6591,46 +6590,60 @@ static ssize_t check_direct_IO(struct btrfs_root *root, int rw, struct kiocb *io
 		goto out;
 
 	/* Check the memory alignment.  Blocks cannot straddle pages */
-	for (seg = 0; seg < nr_segs; seg++) {
-		addr = (unsigned long)iov[seg].iov_base;
-		size = iov[seg].iov_len;
-		end += size;
-		if ((addr & blocksize_mask) || (size & blocksize_mask))
-			goto out;
+	if (iov_iter_has_iovec(iter)) {
+		const struct iovec *iov = iov_iter_iovec(iter);
+
+		for (seg = 0; seg < iter->nr_segs; seg++) {
+			addr = (unsigned long)iov[seg].iov_base;
+				size = iov[seg].iov_len;
+			end += size;
+			if ((addr & blocksize_mask) || (size & blocksize_mask))
+				goto out;
 
-		/* If this is a write we don't need to check anymore */
-		if (rw & WRITE)
-			continue;
+			/* If this is a write we don't need to check anymore */
+			if (rw & WRITE)
+				continue;
 
-		/*
-		 * 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 (i = seg + 1; i < nr_segs; i++) {
-			if (iov[seg].iov_base == iov[i].iov_base)
+			/*
+			 * 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 (i = seg + 1; i < iter->nr_segs; i++) {
+				if (iov[seg].iov_base == iov[i].iov_base)
+					goto out;
+			}
+		}
+	} else if (iov_iter_has_bvec(iter)) {
+		struct bio_vec *bvec = iov_iter_bvec(iter);
+
+		for (seg = 0; seg < iter->nr_segs; seg++) {
+			addr = (unsigned long)bvec[seg].bv_offset;
+			size = bvec[seg].bv_len;
+			end += size;
+			if ((addr & blocksize_mask) || (size & blocksize_mask))
 				goto out;
 		}
-	}
+	} else
+		BUG();
+
 	retval = 0;
 out:
 	return retval;
 }
 
 static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
-			const struct iovec *iov, loff_t offset,
-			unsigned long nr_segs)
+			       struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 
-	if (check_direct_IO(BTRFS_I(inode)->root, rw, iocb, iov,
-			    offset, nr_segs))
+	if (check_direct_IO(BTRFS_I(inode)->root, rw, iocb, iter, offset))
 		return 0;
 
 	return __blockdev_direct_IO(rw, iocb, inode,
 		   BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev,
-		   iov, offset, nr_segs, btrfs_get_blocks_direct, NULL,
+		   iter, offset, btrfs_get_blocks_direct, NULL,
 		   btrfs_submit_direct, 0);
 }
 

@@ -1198,8 +1198,7 @@ static int ceph_write_end(struct file *file, struct address_space *mapping,
  * never get called.
  */
 static ssize_t ceph_direct_io(int rw, struct kiocb *iocb,
-			      const struct iovec *iov,
-			      loff_t pos, unsigned long nr_segs)
+			      struct iov_iter *iter, loff_t pos)
 {
 	WARN_ON(1);
 	return -EINVAL;

@@ -1047,9 +1047,9 @@ static inline int drop_refcount(struct dio *dio)
  */
 static inline ssize_t
 do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
-	struct block_device *bdev, const struct iovec *iov, loff_t offset, 
-	unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
-	dio_submit_t submit_io,	int flags)
+	struct block_device *bdev, struct iov_iter *iter, loff_t offset,
+	get_block_t get_block, dio_iodone_t end_io, dio_submit_t submit_io,
+	int flags)
 {
 	int seg;
 	size_t size;

@@ -1065,6 +1065,8 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 	size_t bytes;
 	struct buffer_head map_bh = { 0, };
 	struct blk_plug plug;
+	const struct iovec *iov = iov_iter_iovec(iter);
+	unsigned long nr_segs = iter->nr_segs;
 
 	if (rw & WRITE)
 		rw = WRITE_ODIRECT;

@@ -1283,9 +1285,9 @@ out:
 
 ssize_t
 __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
-	struct block_device *bdev, const struct iovec *iov, loff_t offset,
-	unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
-	dio_submit_t submit_io,	int flags)
+	struct block_device *bdev, struct iov_iter *iter, loff_t offset,
+	get_block_t get_block, dio_iodone_t end_io, dio_submit_t submit_io,
+	int flags)
 {
 	/*
 	 * The block device state is needed in the end to finally

@@ -1299,9 +1301,8 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 	prefetch(bdev->bd_queue);
 	prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES);
 
-	return do_blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
-				     nr_segs, get_block, end_io,
-				     submit_io, flags);
+	return do_blockdev_direct_IO(rw, iocb, inode, bdev, iter, offset,
+				     get_block, end_io, submit_io, flags);
 }
 
 EXPORT_SYMBOL(__blockdev_direct_IO);

@@ -833,18 +833,16 @@ static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
 }
 
 static ssize_t
-ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-			loff_t offset, unsigned long nr_segs)
+ext2_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				 ext2_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, ext2_get_block);
 	if (ret < 0 && (rw & WRITE))
-		ext2_write_failed(mapping, offset + iov_length(iov, nr_segs));
+		ext2_write_failed(mapping, offset + iov_iter_count(iter));
 	return ret;
 }
 

@@ -1855,8 +1855,7 @@ static int ext3_releasepage(struct page *page, gfp_t wait)
  * VFS code falls back into buffered path in that case so we are safe.
  */
 static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
-			const struct iovec *iov, loff_t offset,
-			unsigned long nr_segs)
+			struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;

@@ -1864,10 +1863,10 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
 	handle_t *handle;
 	ssize_t ret;
 	int orphan = 0;
-	size_t count = iov_length(iov, nr_segs);
+	size_t count = iov_iter_count(iter);
 	int retries = 0;
 
-	trace_ext3_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
+	trace_ext3_direct_IO_enter(inode, offset, count, rw);
 
 	if (rw == WRITE) {
 		loff_t final_size = offset + count;

@@ -1891,15 +1890,14 @@ static ssize_t ext3_direct_IO(int rw, struct kiocb *iocb,
 	}
 
 retry:
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				 ext3_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, ext3_get_block);
 	/*
 	 * In case of error extending write may have instantiated a few
 	 * blocks outside i_size. Trim these off again.
 	 */
 	if (unlikely((rw & WRITE) && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + count;
 
 		if (end > isize)
 			ext3_truncate_failed_direct_write(inode);

@@ -1942,8 +1940,7 @@ retry:
 			ret = err;
 	}
 out:
-	trace_ext3_direct_IO_exit(inode, offset,
-				iov_length(iov, nr_segs), rw, ret);
+	trace_ext3_direct_IO_exit(inode, offset, count, rw, ret);
 	return ret;
 }
 

@@ -2098,8 +2098,7 @@ extern void ext4_da_update_reserve_space(struct inode *inode,
 extern int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 				struct ext4_map_blocks *map, int flags);
 extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
-				const struct iovec *iov, loff_t offset,
-				unsigned long nr_segs);
+				struct iov_iter *iter, loff_t offset);
 extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
 extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk);
 extern void ext4_ind_truncate(struct inode *inode);

@@ -772,8 +772,7 @@ out:
  * VFS code falls back into buffered path in that case so we are safe.
  */
 ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
-			   const struct iovec *iov, loff_t offset,
-			   unsigned long nr_segs)
+			   struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;

@@ -781,7 +780,7 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
 	handle_t *handle;
 	ssize_t ret;
 	int orphan = 0;
-	size_t count = iov_length(iov, nr_segs);
+	size_t count = iov_iter_count(iter);
 	int retries = 0;
 
 	if (rw == WRITE) {

@@ -825,18 +824,17 @@ retry:
 			goto locked;
 		}
 		ret = __blockdev_direct_IO(rw, iocb, inode,
-				 inode->i_sb->s_bdev, iov,
-				 offset, nr_segs,
-				 ext4_get_block, NULL, NULL, 0);
+				 inode->i_sb->s_bdev, iter,
+				 offset, ext4_get_block, NULL, NULL, 0);
 		inode_dio_done(inode);
 	} else {
 locked:
-		ret = blockdev_direct_IO(rw, iocb, inode, iov,
-				 offset, nr_segs, ext4_get_block);
+		ret = blockdev_direct_IO(rw, iocb, inode, iter,
+				 offset, ext4_get_block);
 
 		if (unlikely((rw & WRITE) && ret < 0)) {
 			loff_t isize = i_size_read(inode);
-			loff_t end = offset + iov_length(iov, nr_segs);
+			loff_t end = offset + iov_iter_count(iter);
 
 			if (end > isize)
 				ext4_truncate_failed_write(inode);

@@ -3072,13 +3072,12 @@ retry:
  *
  */
 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
-			      const struct iovec *iov, loff_t offset,
-			      unsigned long nr_segs)
+			      struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 	ssize_t ret;
-	size_t count = iov_length(iov, nr_segs);
+	size_t count = iov_iter_count(iter);
 	int overwrite = 0;
 	get_block_t *get_block_func = NULL;
 	int dio_flags = 0;

@@ -3086,7 +3085,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 
 	/* Use the old path for reads and writes beyond i_size. */
 	if (rw != WRITE || final_size > inode->i_size)
-		return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
+		return ext4_ind_direct_IO(rw, iocb, iter, offset);
 
 	BUG_ON(iocb->private == NULL);
 

@@ -3144,8 +3143,8 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 		dio_flags = DIO_LOCKING;
 	}
 	ret = __blockdev_direct_IO(rw, iocb, inode,
-				   inode->i_sb->s_bdev, iov,
-				   offset, nr_segs,
+				   inode->i_sb->s_bdev, iter,
+				   offset,
 				   get_block_func,
 				   ext4_end_io_dio,
 				   NULL,

@@ -3196,8 +3195,7 @@ retake_lock:
 }
 
 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
-			      const struct iovec *iov, loff_t offset,
-			      unsigned long nr_segs)
+			      struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;

@@ -3213,13 +3211,12 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
 	if (ext4_has_inline_data(inode))
 		return 0;
 
-	trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
+	trace_ext4_direct_IO_enter(inode, offset, iov_iter_count(iter), rw);
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-		ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
+		ret = ext4_ext_direct_IO(rw, iocb, iter, offset);
 	else
-		ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
-	trace_ext4_direct_IO_exit(inode, offset,
-				iov_length(iov, nr_segs), rw, ret);
+		ret = ext4_ind_direct_IO(rw, iocb, iter, offset);
+	trace_ext4_direct_IO_exit(inode, offset, iov_iter_count(iter), rw, ret);
 	return ret;
 }
 

@@ -654,7 +654,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 }
 
 static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
-		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+		struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;

@@ -663,7 +663,7 @@ static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
 		return 0;
 
 	/* Needs synchronization with the cleaner */
-	return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+	return blockdev_direct_IO(rw, iocb, inode, iter, offset,
 						  get_data_block_ro);
 }
 

@@ -185,8 +185,7 @@ static int fat_write_end(struct file *file, struct address_space *mapping,
 }
 
 static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
-			     const struct iovec *iov,
-			     loff_t offset, unsigned long nr_segs)
+			     struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;

@@ -203,7 +202,7 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
 		 *
 		 * Return 0, and fallback to normal buffered write.
 		 */
-		loff_t size = offset + iov_length(iov, nr_segs);
+		loff_t size = offset + iov_iter_count(iter);
 		if (MSDOS_I(inode)->mmu_private < size)
 			return 0;
 	}

@@ -212,10 +211,9 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
 	 * FAT need to use the DIO_LOCKING for avoiding the race
 	 * condition of fat_get_block() and ->truncate().
 	 */
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				 fat_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, fat_get_block);
 	if (ret < 0 && (rw & WRITE))
-		fat_write_failed(mapping, offset + iov_length(iov, nr_segs));
+		fat_write_failed(mapping, offset + iov_iter_count(iter));
 
 	return ret;
 }

@@ -2149,17 +2149,22 @@ static ssize_t fuse_loop_dio(struct file *filp, const struct iovec *iov,
 
 
 static ssize_t
-fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-			loff_t offset, unsigned long nr_segs)
+fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 {
 	ssize_t ret = 0;
 	struct file *file = NULL;
 	loff_t pos = 0;
 
+	/*
+	 * We'll eventually want to work with both iovec and bvec
+	 */
+	BUG_ON(!iov_iter_has_iovec(iter));
+
 	file = iocb->ki_filp;
 	pos = offset;
 
-	ret = fuse_loop_dio(file, iov, nr_segs, &pos, rw);
+	ret = fuse_loop_dio(file, iov_iter_iovec(iter), iter->nr_segs, &pos,
+			    rw);
 
 	return ret;
 }

@@ -995,8 +995,7 @@ static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 
 
 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
-			      const struct iovec *iov, loff_t offset,
-			      unsigned long nr_segs)
+			      struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;

@@ -1020,8 +1019,8 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 	if (rv != 1)
 		goto out; /* dio not valid, fall back to buffered i/o */
 
-	rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
-				  offset, nr_segs, gfs2_get_block_direct,
+	rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iter,
+				  offset, gfs2_get_block_direct,
 				  NULL, NULL, 0);
 out:
 	gfs2_glock_dq(&gh);

@@ -124,15 +124,14 @@ static int hfs_releasepage(struct page *page, gfp_t mask)
 }
 
 static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
-		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+		struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				 hfs_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, hfs_get_block);
 
 	/*
 	 * In case of error extending write may have instantiated a few

@@ -140,7 +139,7 @@ static ssize_t hfs_direct_IO(int rw, struct kiocb *iocb,
 	 */
 	if (unlikely((rw & WRITE) && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + iov_iter_count(iter);
 
 		if (end > isize)
 			hfs_write_failed(mapping, end);

@@ -120,14 +120,14 @@ static int hfsplus_releasepage(struct page *page, gfp_t mask)
 }
 
 static ssize_t hfsplus_direct_IO(int rw, struct kiocb *iocb,
-		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+		struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset,
 				 hfsplus_get_block);
 
 	/*

@@ -136,7 +136,7 @@ static ssize_t hfsplus_direct_IO(int rw, struct kiocb *iocb,
 	 */
 	if (unlikely((rw & WRITE) && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + iov_iter_count(iter);
 
 		if (end > isize)
 			hfsplus_write_failed(mapping, end);

@@ -330,15 +330,14 @@ static sector_t jfs_bmap(struct address_space *mapping, sector_t block)
 }
 
 static ssize_t jfs_direct_IO(int rw, struct kiocb *iocb,
-	const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+			     struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = file->f_mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				 jfs_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, jfs_get_block);
 
 	/*
 	 * In case of error extending write may have instantiated a few

@@ -346,7 +345,7 @@ static ssize_t jfs_direct_IO(int rw, struct kiocb *iocb,
 	 */
 	if (unlikely((rw & WRITE) && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + iov_iter_count(iter);
 
 		if (end > isize)
 			jfs_write_failed(mapping, end);

@@ -112,7 +112,7 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
  * nfs_direct_IO - NFS address space operation for direct I/O
  * @rw: direction (read or write)
  * @iocb: target I/O control block
- * @iov: array of vectors that define I/O buffer
+ * @iter: array of vectors that define I/O buffer
  * @pos: offset in file to begin the operation
  * @nr_segs: size of iovec array
  *

@@ -121,22 +121,25 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
  * shunt off direct read and write requests before the VFS gets them,
  * so this method is only ever called for swap.
  */
-ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
+ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
+		      loff_t pos)
 {
 #ifndef CONFIG_NFS_SWAP
 	dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
 			iocb->ki_filp->f_path.dentry->d_name.name,
-			(long long) pos, nr_segs);
+			(long long) pos, iter->nr_segs);
 
 	return -EINVAL;
 #else
+	const struct iovec *iov = iov_iter_iovec(iter);
+
 	VM_BUG_ON(iocb->ki_left != PAGE_SIZE);
 	VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
 
 	if (rw == READ || rw == KERNEL_READ)
-		return nfs_file_direct_read(iocb, iov, nr_segs, pos,
+		return nfs_file_direct_read(iocb, iov, iter->nr_segs, pos,
 				rw == READ ? true : false);
-	return nfs_file_direct_write(iocb, iov, nr_segs, pos,
+	return nfs_file_direct_write(iocb, iov, iter->nr_segs, pos,
 				rw == WRITE ? true : false);
 #endif /* CONFIG_NFS_SWAP */
 }

@@ -262,8 +262,8 @@ static int nilfs_write_end(struct file *file, struct address_space *mapping,
 }
 
 static ssize_t
-nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-		loff_t offset, unsigned long nr_segs)
+nilfs_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
+		loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;

@@ -274,7 +274,7 @@ nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 		return 0;
 
 	/* Needs synchronization with the cleaner */
-	size = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+	size = blockdev_direct_IO(rw, iocb, inode, iter, offset,
 				  nilfs_get_block);
 
 	/*

@@ -283,7 +283,7 @@ nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 	 */
 	if (unlikely((rw & WRITE) && size < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + iov_iter_count(iter);
 
 		if (end > isize)
 			nilfs_write_failed(mapping, end);

@@ -621,9 +621,8 @@ static int ocfs2_releasepage(struct page *page, gfp_t wait)
 
 static ssize_t ocfs2_direct_IO(int rw,
 			       struct kiocb *iocb,
-			       const struct iovec *iov,
-			       loff_t offset,
-			       unsigned long nr_segs)
+			       struct iov_iter *iter,
+			       loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;

@@ -640,8 +639,7 @@ static ssize_t ocfs2_direct_IO(int rw,
 		return 0;
 
 	return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev,
-				    iov, offset, nr_segs,
-				    ocfs2_direct_IO_get_blocks,
+				    iter, offset, ocfs2_direct_IO_get_blocks,
 				    ocfs2_dio_end_io, NULL, 0);
 }
 

@@ -3067,14 +3067,13 @@ static int reiserfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 /* We thank Mingming Cao for helping us understand in great detail what
    to do in this section of the code. */
 static ssize_t reiserfs_direct_IO(int rw, struct kiocb *iocb,
-				  const struct iovec *iov, loff_t offset,
-				  unsigned long nr_segs)
+				  struct iov_iter *iter, loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset,
 				  reiserfs_get_blocks_direct_io);
 
 	/*

@@ -3083,7 +3082,7 @@ static ssize_t reiserfs_direct_IO(int rw, struct kiocb *iocb,
 	 */
 	if (unlikely((rw & WRITE) && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + iov_length(iov, nr_segs);
+		loff_t end = offset + iov_iter_count(iter);
 
 		if ((end > isize) && inode_newsize_ok(inode, isize) == 0) {
 			truncate_setsize(inode, isize);

@@ -119,8 +119,7 @@ static int udf_adinicb_write_end(struct file *file,
 }
 
 static ssize_t udf_adinicb_direct_IO(int rw, struct kiocb *iocb,
-				     const struct iovec *iov,
-				     loff_t offset, unsigned long nr_segs)
+				     struct iov_iter *iter, loff_t offset)
 {
 	/* Fallback to buffered I/O. */
 	return 0;

@@ -145,19 +145,17 @@ static int udf_write_begin(struct file *file, struct address_space *mapping,
 	return ret;
 }
 
-static ssize_t udf_direct_IO(int rw, struct kiocb *iocb,
-			     const struct iovec *iov,
-			     loff_t offset, unsigned long nr_segs)
+static ssize_t udf_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
+			     loff_t offset)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = mapping->host;
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
-				  udf_get_block);
+	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, udf_get_block);
 	if (unlikely(ret < 0 && (rw & WRITE)))
-		udf_write_failed(mapping, offset + iov_length(iov, nr_segs));
+		udf_write_failed(mapping, offset + iov_iter_count(iter));
 	return ret;
 }