generic_file_direct_write(): switch to iov_iter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/btrfs/file.c

@@ -1669,15 +1669,13 @@ static ssize_t __btrfs_direct_write(struct kiocb *iocb,
 	loff_t endbyte;
 	int err;
 
-	written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
-					    count, ocount);
+	iov_iter_init(&i, iov, nr_segs, count, 0);
+	written = generic_file_direct_write(iocb, &i, pos, count, ocount);
 
 	if (written < 0 || written == count)
 		return written;
 
 	pos += written;
-	count -= written;
-	iov_iter_init(&i, iov, nr_segs, count, written);
 	written_buffered = __btrfs_buffered_write(file, &i, pos);
 	if (written_buffered < 0) {
 		err = written_buffered;

fs/fuse/file.c

@@ -1235,15 +1235,13 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		goto out;
 
 	if (file->f_flags & O_DIRECT) {
-		written = generic_file_direct_write(iocb, iov, &nr_segs, pos, 
-						    count, ocount);
+		iov_iter_init(&i, iov, nr_segs, count, 0);
+		written = generic_file_direct_write(iocb, &i, pos, count, ocount);
 		if (written < 0 || written == count)
 			goto out;
 
 		pos += written;
-		count -= written;
 
-		iov_iter_init(&i, iov, nr_segs, count, written);
 		written_buffered = fuse_perform_write(file, mapping, &i, pos);
 		if (written_buffered < 0) {
 			err = written_buffered;

fs/ocfs2/file.c

@@ -2251,6 +2251,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 	int full_coherency = !(osb->s_mount_opt &
 			       OCFS2_MOUNT_COHERENCY_BUFFERED);
 	int unaligned_dio = 0;
+	struct iov_iter from;
 
 	trace_ocfs2_file_aio_write(inode, file, file->f_path.dentry,
 		(unsigned long long)OCFS2_I(inode)->ip_blkno,
@@ -2365,16 +2366,15 @@ relock:
 	if (ret)
 		goto out_dio;
 
+	iov_iter_init(&from, iov, nr_segs, count, 0);
 	if (direct_io) {
-		written = generic_file_direct_write(iocb, iov, &nr_segs, *ppos,
+		written = generic_file_direct_write(iocb, &from, *ppos,
 						    count, ocount);
 		if (written < 0) {
 			ret = written;
 			goto out_dio;
 		}
 	} else {
-		struct iov_iter from;
-		iov_iter_init(&from, iov, nr_segs, count, 0);
 		current->backing_dev_info = file->f_mapping->backing_dev_info;
 		written = generic_perform_write(file, &from, *ppos);
 		if (likely(written >= 0))

fs/xfs/xfs_file.c

@@ -641,6 +641,7 @@ xfs_file_dio_aio_write(
 	int			iolock;
 	struct xfs_buftarg	*target = XFS_IS_REALTIME_INODE(ip) ?
 					mp->m_rtdev_targp : mp->m_ddev_targp;
+	struct iov_iter		from;
 
 	/* DIO must be aligned to device logical sector size */
 	if ((pos | count) & target->bt_logical_sectormask)
@@ -698,8 +699,8 @@ xfs_file_dio_aio_write(
 	}
 
 	trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
-	ret = generic_file_direct_write(iocb, iovp,
-			&nr_segs, pos, count, ocount);
+	iov_iter_init(&from, iovp, nr_segs, count, 0);
+	ret = generic_file_direct_write(iocb, &from, pos, count, ocount);
 
 out:
 	xfs_rw_iunlock(ip, iolock);

include/linux/fs.h

@@ -2407,8 +2407,8 @@ int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isbl
 extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
 extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long);
 extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
-extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
-		unsigned long *, loff_t, size_t, size_t);
+extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *,
+		loff_t, size_t, size_t);
 extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);

mm/filemap.c

@@ -2385,9 +2385,8 @@ int pagecache_write_end(struct file *file, struct address_space *mapping,
 EXPORT_SYMBOL(pagecache_write_end);
 
 ssize_t
-generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
-		unsigned long *nr_segs, loff_t pos,
-		size_t count, size_t ocount)
+generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
+		loff_t pos, size_t count, size_t ocount)
 {
 	struct file	*file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
@@ -2397,9 +2396,9 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 	pgoff_t		end;
 
 	if (count != ocount)
-		*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
+		from->nr_segs = iov_shorten((struct iovec *)from->iov, from->nr_segs, count);
 
-	write_len = iov_length(iov, *nr_segs);
+	write_len = iov_length(from->iov, from->nr_segs);
 	end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
 
 	written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
@@ -2426,7 +2425,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 		}
 	}
 
-	written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
+	written = mapping->a_ops->direct_IO(WRITE, iocb, from->iov, pos, from->nr_segs);
 
 	/*
 	 * Finally, try again to invalidate clean pages which might have been
@@ -2443,6 +2442,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 
 	if (written > 0) {
 		pos += written;
+		iov_iter_advance(from, written);
 		if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
 			i_size_write(inode, pos);
 			mark_inode_dirty(inode);
@@ -2645,11 +2645,10 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	if (unlikely(file->f_flags & O_DIRECT)) {
 		loff_t endbyte;
 
-		written = generic_file_direct_write(iocb, iov, &from.nr_segs, pos,
+		written = generic_file_direct_write(iocb, &from, pos,
 							count, ocount);
 		if (written < 0 || written == count)
 			goto out;
-		iov_iter_advance(&from, written);
 
 		/*
 		 * direct-io write to a hole: fall through to buffered I/O