1 files changed, 461 insertions, 0 deletions
diff --git a/fs/bcachefs/thread_with_file.c b/fs/bcachefs/thread_with_file.c
new file mode 100644
index 000000000000..b1af7ac430f6
--- /dev/null
+++ b/fs/bcachefs/thread_with_file.c
@@ -0,0 +1,461 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef NO_BCACHEFS_FS
+
+#include "bcachefs.h"
+#include "thread_with_file.h"
+
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/poll.h>
+#include <linux/sched/sysctl.h>
+
+void bch2_thread_with_file_exit(struct thread_with_file *thr)
+{
+	if (thr->task) {
+		kthread_stop(thr->task);
+		put_task_struct(thr->task);
+	}
+}
+
+int bch2_run_thread_with_file(struct thread_with_file *thr,
+			      const struct file_operations *fops,
+			      int (*fn)(void *))
+{
+	struct file *file = NULL;
+	int ret, fd = -1;
+	unsigned fd_flags = O_CLOEXEC;
+
+	if (fops->read && fops->write)
+		fd_flags |= O_RDWR;
+	else if (fops->read)
+		fd_flags |= O_RDONLY;
+	else if (fops->write)
+		fd_flags |= O_WRONLY;
+
+	char name[TASK_COMM_LEN];
+	get_task_comm(name, current);
+
+	thr->ret = 0;
+	thr->task = kthread_create(fn, thr, "%s", name);
+	ret = PTR_ERR_OR_ZERO(thr->task);
+	if (ret)
+		return ret;
+
+	ret = get_unused_fd_flags(fd_flags);
+	if (ret < 0)
+		goto err;
+	fd = ret;
+
+	file = anon_inode_getfile(name, fops, thr, fd_flags);
+	ret = PTR_ERR_OR_ZERO(file);
+	if (ret)
+		goto err;
+
+	get_task_struct(thr->task);
+	wake_up_process(thr->task);
+	fd_install(fd, file);
+	return fd;
+err:
+	if (fd >= 0)
+		put_unused_fd(fd);
+	if (thr->task)
+		kthread_stop(thr->task);
+	return ret;
+}
+
+/* stdio_redirect */
+
+static bool stdio_redirect_has_input(struct stdio_redirect *stdio)
+{
+	return stdio->input.buf.nr || stdio->done;
+}
+
+static bool stdio_redirect_has_output(struct stdio_redirect *stdio)
+{
+	return stdio->output.buf.nr || stdio->done;
+}
+
+#define STDIO_REDIRECT_BUFSIZE		4096
+
+static bool stdio_redirect_has_input_space(struct stdio_redirect *stdio)
+{
+	return stdio->input.buf.nr < STDIO_REDIRECT_BUFSIZE || stdio->done;
+}
+
+static bool stdio_redirect_has_output_space(struct stdio_redirect *stdio)
+{
+	return stdio->output.buf.nr < STDIO_REDIRECT_BUFSIZE || stdio->done;
+}
+
+static void stdio_buf_init(struct stdio_buf *buf)
+{
+	spin_lock_init(&buf->lock);
+	init_waitqueue_head(&buf->wait);
+	darray_init(&buf->buf);
+}
+
+/* thread_with_stdio */
+
+static void thread_with_stdio_done(struct thread_with_stdio *thr)
+{
+	thr->thr.done = true;
+	thr->stdio.done = true;
+	wake_up(&thr->stdio.input.wait);
+	wake_up(&thr->stdio.output.wait);
+}
+
+static ssize_t thread_with_stdio_read(struct file *file, char __user *ubuf,
+				      size_t len, loff_t *ppos)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+	struct stdio_buf *buf = &thr->stdio.output;
+	size_t copied = 0, b;
+	int ret = 0;
+
+	if (!(file->f_flags & O_NONBLOCK)) {
+		ret = wait_event_interruptible(buf->wait, stdio_redirect_has_output(&thr->stdio));
+		if (ret)
+			return ret;
+	} else if (!stdio_redirect_has_output(&thr->stdio))
+		return -EAGAIN;
+
+	while (len && buf->buf.nr) {
+		if (fault_in_writeable(ubuf, len) == len) {
+			ret = -EFAULT;
+			break;
+		}
+
+		spin_lock_irq(&buf->lock);
+		b = min_t(size_t, len, buf->buf.nr);
+
+		if (b && !copy_to_user_nofault(ubuf, buf->buf.data, b)) {
+			ubuf	+= b;
+			len	-= b;
+			copied	+= b;
+			buf->buf.nr -= b;
+			memmove(buf->buf.data,
+				buf->buf.data + b,
+				buf->buf.nr);
+		}
+		spin_unlock_irq(&buf->lock);
+	}
+
+	return copied ?: ret;
+}
+
+static int thread_with_stdio_release(struct inode *inode, struct file *file)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+
+	thread_with_stdio_done(thr);
+	bch2_thread_with_file_exit(&thr->thr);
+	darray_exit(&thr->stdio.input.buf);
+	darray_exit(&thr->stdio.output.buf);
+	thr->ops->exit(thr);
+	return 0;
+}
+
+static ssize_t thread_with_stdio_write(struct file *file, const char __user *ubuf,
+				       size_t len, loff_t *ppos)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+	struct stdio_buf *buf = &thr->stdio.input;
+	size_t copied = 0;
+	ssize_t ret = 0;
+
+	while (len) {
+		if (thr->thr.done) {
+			ret = -EPIPE;
+			break;
+		}
+
+		size_t b = len - fault_in_readable(ubuf, len);
+		if (!b) {
+			ret = -EFAULT;
+			break;
+		}
+
+		spin_lock(&buf->lock);
+		if (buf->buf.nr < STDIO_REDIRECT_BUFSIZE)
+			darray_make_room_gfp(&buf->buf,
+				min(b, STDIO_REDIRECT_BUFSIZE - buf->buf.nr), GFP_NOWAIT);
+		b = min(len, darray_room(buf->buf));
+
+		if (b && !copy_from_user_nofault(&darray_top(buf->buf), ubuf, b)) {
+			buf->buf.nr += b;
+			ubuf	+= b;
+			len	-= b;
+			copied	+= b;
+		}
+		spin_unlock(&buf->lock);
+
+		if (b) {
+			wake_up(&buf->wait);
+		} else {
+			if ((file->f_flags & O_NONBLOCK)) {
+				ret = -EAGAIN;
+				break;
+			}
+
+			ret = wait_event_interruptible(buf->wait,
+					stdio_redirect_has_input_space(&thr->stdio));
+			if (ret)
+				break;
+		}
+	}
+
+	return copied ?: ret;
+}
+
+static __poll_t thread_with_stdio_poll(struct file *file, struct poll_table_struct *wait)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+
+	poll_wait(file, &thr->stdio.output.wait, wait);
+	poll_wait(file, &thr->stdio.input.wait, wait);
+
+	__poll_t mask = 0;
+
+	if (stdio_redirect_has_output(&thr->stdio))
+		mask |= EPOLLIN;
+	if (stdio_redirect_has_input_space(&thr->stdio))
+		mask |= EPOLLOUT;
+	if (thr->thr.done)
+		mask |= EPOLLHUP|EPOLLERR;
+	return mask;
+}
+
+static __poll_t thread_with_stdout_poll(struct file *file, struct poll_table_struct *wait)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+
+	poll_wait(file, &thr->stdio.output.wait, wait);
+
+	__poll_t mask = 0;
+
+	if (stdio_redirect_has_output(&thr->stdio))
+		mask |= EPOLLIN;
+	if (thr->thr.done)
+		mask |= EPOLLHUP|EPOLLERR;
+	return mask;
+}
+
+static int thread_with_stdio_flush(struct file *file, fl_owner_t id)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+
+	return thr->thr.ret;
+}
+
+static long thread_with_stdio_ioctl(struct file *file, unsigned int cmd, unsigned long p)
+{
+	struct thread_with_stdio *thr =
+		container_of(file->private_data, struct thread_with_stdio, thr);
+
+	if (thr->ops->unlocked_ioctl)
+		return thr->ops->unlocked_ioctl(thr, cmd, p);
+	return -ENOTTY;
+}
+
+static const struct file_operations thread_with_stdio_fops = {
+	.llseek		= no_llseek,
+	.read		= thread_with_stdio_read,
+	.write		= thread_with_stdio_write,
+	.poll		= thread_with_stdio_poll,
+	.flush		= thread_with_stdio_flush,
+	.release	= thread_with_stdio_release,
+	.unlocked_ioctl	= thread_with_stdio_ioctl,
+};
+
+static const struct file_operations thread_with_stdout_fops = {
+	.llseek		= no_llseek,
+	.read		= thread_with_stdio_read,
+	.poll		= thread_with_stdout_poll,
+	.flush		= thread_with_stdio_flush,
+	.release	= thread_with_stdio_release,
+	.unlocked_ioctl	= thread_with_stdio_ioctl,
+};
+
+static int thread_with_stdio_fn(void *arg)
+{
+	struct thread_with_stdio *thr = arg;
+
+	thr->thr.ret = thr->ops->fn(thr);
+
+	thread_with_stdio_done(thr);
+	return 0;
+}
+
+void bch2_thread_with_stdio_init(struct thread_with_stdio *thr,
+				 const struct thread_with_stdio_ops *ops)
+{
+	stdio_buf_init(&thr->stdio.input);
+	stdio_buf_init(&thr->stdio.output);
+	thr->ops = ops;
+}
+
+int __bch2_run_thread_with_stdio(struct thread_with_stdio *thr)
+{
+	return bch2_run_thread_with_file(&thr->thr, &thread_with_stdio_fops, thread_with_stdio_fn);
+}
+
+int bch2_run_thread_with_stdio(struct thread_with_stdio *thr,
+			       const struct thread_with_stdio_ops *ops)
+{
+	bch2_thread_with_stdio_init(thr, ops);
+
+	return __bch2_run_thread_with_stdio(thr);
+}
+
+int bch2_run_thread_with_stdout(struct thread_with_stdio *thr,
+				const struct thread_with_stdio_ops *ops)
+{
+	stdio_buf_init(&thr->stdio.input);
+	stdio_buf_init(&thr->stdio.output);
+	thr->ops = ops;
+
+	return bch2_run_thread_with_file(&thr->thr, &thread_with_stdout_fops, thread_with_stdio_fn);
+}
+EXPORT_SYMBOL_GPL(bch2_run_thread_with_stdout);
+
+int bch2_stdio_redirect_read(struct stdio_redirect *stdio, char *ubuf, size_t len)
+{
+	struct stdio_buf *buf = &stdio->input;
+
+	/*
+	 * we're waiting on user input (or for the file descriptor to be
+	 * closed), don't want a hung task warning:
+	 */
+	do {
+		wait_event_timeout(buf->wait, stdio_redirect_has_input(stdio),
+				   sysctl_hung_task_timeout_secs * HZ / 2);
+	} while (!stdio_redirect_has_input(stdio));
+
+	if (stdio->done)
+		return -1;
+
+	spin_lock(&buf->lock);
+	int ret = min(len, buf->buf.nr);
+	buf->buf.nr -= ret;
+	memcpy(ubuf, buf->buf.data, ret);
+	memmove(buf->buf.data,
+		buf->buf.data + ret,
+		buf->buf.nr);
+	spin_unlock(&buf->lock);
+
+	wake_up(&buf->wait);
+	return ret;
+}
+
+int bch2_stdio_redirect_readline(struct stdio_redirect *stdio, char *ubuf, size_t len)
+{
+	struct stdio_buf *buf = &stdio->input;
+	size_t copied = 0;
+	ssize_t ret = 0;
+again:
+	do {
+		wait_event_timeout(buf->wait, stdio_redirect_has_input(stdio),
+				   sysctl_hung_task_timeout_secs * HZ / 2);
+	} while (!stdio_redirect_has_input(stdio));
+
+	if (stdio->done) {
+		ret = -1;
+		goto out;
+	}
+
+	spin_lock(&buf->lock);
+	size_t b = min(len, buf->buf.nr);
+	char *n = memchr(buf->buf.data, '\n', b);
+	if (n)
+		b = min_t(size_t, b, n + 1 - buf->buf.data);
+	buf->buf.nr -= b;
+	memcpy(ubuf, buf->buf.data, b);
+	memmove(buf->buf.data,
+		buf->buf.data + b,
+		buf->buf.nr);
+	ubuf += b;
+	len -= b;
+	copied += b;
+	spin_unlock(&buf->lock);
+
+	wake_up(&buf->wait);
+
+	if (!n && len)
+		goto again;
+out:
+	return copied ?: ret;
+}
+
+__printf(3, 0)
+static ssize_t bch2_darray_vprintf(darray_char *out, gfp_t gfp, const char *fmt, va_list args)
+{
+	ssize_t ret;
+
+	do {
+		va_list args2;
+		size_t len;
+
+		va_copy(args2, args);
+		len = vsnprintf(out->data + out->nr, darray_room(*out), fmt, args2);
+		va_end(args2);
+
+		if (len + 1 <= darray_room(*out)) {
+			out->nr += len;
+			return len;
+		}
+
+		ret = darray_make_room_gfp(out, len + 1, gfp);
+	} while (ret == 0);
+
+	return ret;
+}
+
+ssize_t bch2_stdio_redirect_vprintf(struct stdio_redirect *stdio, bool nonblocking,
+				    const char *fmt, va_list args)
+{
+	struct stdio_buf *buf = &stdio->output;
+	unsigned long flags;
+	ssize_t ret;
+
+again:
+	spin_lock_irqsave(&buf->lock, flags);
+	ret = bch2_darray_vprintf(&buf->buf, GFP_NOWAIT, fmt, args);
+	spin_unlock_irqrestore(&buf->lock, flags);
+
+	if (ret < 0) {
+		if (nonblocking)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(buf->wait,
+				stdio_redirect_has_output_space(stdio));
+		if (ret)
+			return ret;
+		goto again;
+	}
+
+	wake_up(&buf->wait);
+	return ret;
+}
+
+ssize_t bch2_stdio_redirect_printf(struct stdio_redirect *stdio, bool nonblocking,
+				const char *fmt, ...)
+{
+	va_list args;
+	ssize_t ret;
+
+	va_start(args, fmt);
+	ret = bch2_stdio_redirect_vprintf(stdio, nonblocking, fmt, args);
+	va_end(args);
+
+	return ret;
+}
+
+#endif /* NO_BCACHEFS_FS */