switch pipe_read() to copy_page_to_iter() (637b58c2) · Commits · e / devices / android_kernel_xiaomi_markw

fs/pipe.c

+8 −71

Original line number	Diff line number	Diff line
		@@ -142,55 +142,6 @@ pipe_iov_copy_from_user(void to, struct iovec iov, unsigned long len,
		return 0;
		}

		static int
		pipe_iov_copy_to_user(struct iovec iov, const void from, unsigned long len,
		int atomic)
		{
		unsigned long copy;

		while (len > 0) {
		while (!iov->iov_len)
		iov++;
		copy = min_t(unsigned long, len, iov->iov_len);

		if (atomic) {
		if (__copy_to_user_inatomic(iov->iov_base, from, copy))
		return -EFAULT;
		} else {
		if (copy_to_user(iov->iov_base, from, copy))
		return -EFAULT;
		}
		from += copy;
		len -= copy;
		iov->iov_base += copy;
		iov->iov_len -= copy;
		}
		return 0;
		}

		/*
		* Attempt to pre-fault in the user memory, so we can use atomic copies.
		* Returns the number of bytes not faulted in.
		*/
		static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
		{
		while (!iov->iov_len)
		iov++;

		while (len > 0) {
		unsigned long this_len;

		this_len = min_t(unsigned long, len, iov->iov_len);
		if (fault_in_pages_writeable(iov->iov_base, this_len))
		break;

		len -= this_len;
		iov++;
		}

		return len;
		}

		/*
		* Pre-fault in the user memory, so we can use atomic copies.
		*/
		@@ -329,12 +280,15 @@ pipe_read(struct kiocb iocb, const struct iovec _iov,
		ssize_t ret;
		struct iovec iov = (struct iovec )_iov;
		size_t total_len;
		struct iov_iter iter;

		total_len = iov_length(iov, nr_segs);
		/* Null read succeeds. */
		if (unlikely(total_len == 0))
		return 0;

		iov_iter_init(&iter, iov, nr_segs, total_len, 0);

		do_wakeup = 0;
		ret = 0;
		__pipe_lock(pipe);
		@@ -344,9 +298,9 @@ pipe_read(struct kiocb iocb, const struct iovec _iov,
		int curbuf = pipe->curbuf;
		struct pipe_buffer *buf = pipe->bufs + curbuf;
		const struct pipe_buf_operations *ops = buf->ops;
		void *addr;
		size_t chars = buf->len;
		int error, atomic;
		size_t written;
		int error;

		if (chars > total_len)
		chars = total_len;
		@@ -358,27 +312,10 @@ pipe_read(struct kiocb iocb, const struct iovec _iov,
		break;
		}

		atomic = !iov_fault_in_pages_write(iov, chars);
		redo:
		if (atomic)
		addr = kmap_atomic(buf->page);
		else
		addr = kmap(buf->page);
		error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
		if (atomic)
		kunmap_atomic(addr);
		else
		kunmap(buf->page);
		if (unlikely(error)) {
		/*
		* Just retry with the slow path if we failed.
		*/
		if (atomic) {
		atomic = 0;
		goto redo;
		}
		written = copy_page_to_iter(buf->page, buf->offset, chars, &iter);
		if (unlikely(written < chars)) {
		if (!ret)
		ret = error;
		ret = -EFAULT;
		break;
		}
		ret += chars;