[PATCH v4 3/3] io_uring: add support for getdents64

[Stefan Roesch <shr@fb.com>]

This adds support for getdents64 to io_uring.

Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c                 | 52 +++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |  1 +
 2 files changed, 53 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 08b1b3de9b3f..8fdff4745742 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -691,6 +691,13 @@ struct io_hardlink {
 	int				flags;
 };
 
+struct io_getdents {
+	struct file			*file;
+	struct linux_dirent64 __user	*dirent;
+	unsigned int			count;
+	loff_t				pos;
+};
+
 struct io_async_connect {
 	struct sockaddr_storage		address;
 };
@@ -856,6 +863,7 @@ struct io_kiocb {
 		struct io_mkdir		mkdir;
 		struct io_symlink	symlink;
 		struct io_hardlink	hardlink;
+		struct io_getdents	getdents;
 	};
 
 	u8				opcode;
@@ -1105,6 +1113,9 @@ static const struct io_op_def io_op_defs[] = {
 	[IORING_OP_MKDIRAT] = {},
 	[IORING_OP_SYMLINKAT] = {},
 	[IORING_OP_LINKAT] = {},
+	[IORING_OP_GETDENTS] = {
+		.needs_file		= 1,
+	},
 };
 
 /* requests with any of those set should undergo io_disarm_next() */
@@ -3971,6 +3982,42 @@ static int io_linkat(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
+static int io_getdents_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_getdents *getdents = &req->getdents;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->rw_flags || sqe->buf_index)
+		return -EINVAL;
+
+	getdents->pos = READ_ONCE(sqe->off);
+	getdents->dirent = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	getdents->count = READ_ONCE(sqe->len);
+
+	return 0;
+}
+
+static int io_getdents(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_getdents *getdents = &req->getdents;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = vfs_getdents(req->file, getdents->dirent, getdents->count, getdents->pos);
+	if (ret < 0) {
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+
+		req_set_fail(req);
+	}
+
+	io_req_complete(req, ret);
+	return 0;
+}
+
 static int io_shutdown_prep(struct io_kiocb *req,
 			    const struct io_uring_sqe *sqe)
 {
@@ -6486,6 +6533,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return io_symlinkat_prep(req, sqe);
 	case IORING_OP_LINKAT:
 		return io_linkat_prep(req, sqe);
+	case IORING_OP_GETDENTS:
+		return io_getdents_prep(req, sqe);
 	}
 
 	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6771,6 +6820,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	case IORING_OP_LINKAT:
 		ret = io_linkat(req, issue_flags);
 		break;
+	case IORING_OP_GETDENTS:
+		ret = io_getdents(req, issue_flags);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 787f491f0d2a..57dc88db5793 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -143,6 +143,7 @@ enum {
 	IORING_OP_MKDIRAT,
 	IORING_OP_SYMLINKAT,
 	IORING_OP_LINKAT,
+	IORING_OP_GETDENTS,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.30.2