fs: add vfs_iter_{read,write} helpers
Simple helpers that pass an arbitrary iov_iter to filesystems.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/read_write.c b/fs/read_write.c
index c0805c9..ab4f26a 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -333,6 +333,52 @@
}
#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