Commit dbe4e192 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

fs: add vfs_iter_{read,write} helpers 



Simple helpers that pass an arbitrary iov_iter to filesystems.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 05afcb77

fs/read_write.c

+46 −0
Original line number Diff line number Diff line
@@ -333,6 +333,52 @@ SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned long, offset_high, 
}

#endif



ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos)

{

	struct kiocb kiocb;

	ssize_t ret;



	if (!file->f_op->read_iter)

		return -EINVAL;



	init_sync_kiocb(&kiocb, file);

	kiocb.ki_pos = *ppos;

	kiocb.ki_nbytes = iov_iter_count(iter);



	iter->type |= READ;

	ret = file->f_op->read_iter(&kiocb, iter);

	if (ret == -EIOCBQUEUED)

		ret = wait_on_sync_kiocb(&kiocb);



	if (ret > 0)

		*ppos = kiocb.ki_pos;

	return ret;

}

EXPORT_SYMBOL(vfs_iter_read);



ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos)

{

	struct kiocb kiocb;

	ssize_t ret;



	if (!file->f_op->write_iter)

		return -EINVAL;



	init_sync_kiocb(&kiocb, file);

	kiocb.ki_pos = *ppos;

	kiocb.ki_nbytes = iov_iter_count(iter);



	iter->type |= WRITE;

	ret = file->f_op->write_iter(&kiocb, iter);

	if (ret == -EIOCBQUEUED)

		ret = wait_on_sync_kiocb(&kiocb);



	if (ret > 0)

		*ppos = kiocb.ki_pos;

	return ret;

}

EXPORT_SYMBOL(vfs_iter_write);



/*

 * rw_verify_area doesn't like huge counts. We limit

 * them to something that fits in "int" so that others

fs/splice.c

+2 −14
Original line number Diff line number Diff line
@@ -961,7 +961,6 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 
	splice_from_pipe_begin(&sd);

	while (sd.total_len) {

		struct iov_iter from;

		struct kiocb kiocb;

		size_t left;

		int n, idx;
@@ -1005,26 +1004,15 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 
			left -= this_len;

		}



		/* ... iov_iter */

		iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,

			      sd.total_len - left);



		/* ... and iocb */

		init_sync_kiocb(&kiocb, out);

		kiocb.ki_pos = sd.pos;

		kiocb.ki_nbytes = sd.total_len - left;



		/* now, send it */

		ret = out->f_op->write_iter(&kiocb, &from);

		if (-EIOCBQUEUED == ret)

			ret = wait_on_sync_kiocb(&kiocb);



		ret = vfs_iter_write(out, &from, &sd.pos);

		if (ret <= 0)

			break;



		sd.num_spliced += ret;

		sd.total_len -= ret;

		*ppos = sd.pos = kiocb.ki_pos;

		*ppos = sd.pos;



		/* dismiss the fully eaten buffers, adjust the partial one */

		while (ret) {

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -2494,6 +2494,9 @@ extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t l 
extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);

extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);



ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos);

ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos);



/* fs/block_dev.c */

extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);

extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);