From eddc7ef52a6b37b7ba3d1c8a8fbb63d5d9914f8a Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 13 Dec 2019 21:18:10 -0700
Subject: [PATCH] io_uring: add support for IORING_OP_STATX

This provides support for async statx(2) through io_uring.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 86 ++++++++++++++++++++++++++++++++++-
 include/uapi/linux/io_uring.h |  2 +
 2 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4325068324b7..115c7d413372 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -379,9 +379,13 @@ struct io_sr_msg {
 struct io_open {
 	struct file			*file;
 	int				dfd;
-	umode_t				mode;
+	union {
+		umode_t			mode;
+		unsigned		mask;
+	};
 	const char __user		*fname;
 	struct filename			*filename;
+	struct statx __user		*buffer;
 	int				flags;
 };
 
@@ -2266,6 +2270,74 @@ err:
 	return 0;
 }
 
+static int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	unsigned lookup_flags;
+	int ret;
+
+	if (sqe->ioprio || sqe->buf_index)
+		return -EINVAL;
+
+	req->open.dfd = READ_ONCE(sqe->fd);
+	req->open.mask = READ_ONCE(sqe->len);
+	req->open.fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	req->open.buffer = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	req->open.flags = READ_ONCE(sqe->statx_flags);
+
+	if (vfs_stat_set_lookup_flags(&lookup_flags, req->open.flags))
+		return -EINVAL;
+
+	req->open.filename = getname_flags(req->open.fname, lookup_flags, NULL);
+	if (IS_ERR(req->open.filename)) {
+		ret = PTR_ERR(req->open.filename);
+		req->open.filename = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static int io_statx(struct io_kiocb *req, struct io_kiocb **nxt,
+		    bool force_nonblock)
+{
+	struct io_open *ctx = &req->open;
+	unsigned lookup_flags;
+	struct path path;
+	struct kstat stat;
+	int ret;
+
+	if (force_nonblock)
+		return -EAGAIN;
+
+	if (vfs_stat_set_lookup_flags(&lookup_flags, ctx->flags))
+		return -EINVAL;
+
+retry:
+	/* filename_lookup() drops it, keep a reference */
+	ctx->filename->refcnt++;
+
+	ret = filename_lookup(ctx->dfd, ctx->filename, lookup_flags, &path,
+				NULL);
+	if (ret)
+		goto err;
+
+	ret = vfs_getattr(&path, &stat, ctx->mask, ctx->flags);
+	path_put(&path);
+	if (retry_estale(ret, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
+	if (!ret)
+		ret = cp_statx(&stat, ctx->buffer);
+err:
+	putname(ctx->filename);
+	if (ret < 0)
+		req_set_fail_links(req);
+	io_cqring_add_event(req, ret);
+	io_put_req_find_next(req, nxt);
+	return 0;
+}
+
 static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	/*
@@ -3427,6 +3499,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
 	case IORING_OP_FILES_UPDATE:
 		ret = io_files_update_prep(req, sqe);
 		break;
+	case IORING_OP_STATX:
+		ret = io_statx_prep(req, sqe);
+		break;
 	default:
 		printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
 				req->opcode);
@@ -3613,6 +3688,14 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		}
 		ret = io_files_update(req, force_nonblock);
 		break;
+	case IORING_OP_STATX:
+		if (sqe) {
+			ret = io_statx_prep(req, sqe);
+			if (ret)
+				break;
+		}
+		ret = io_statx(req, nxt, force_nonblock);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -3699,6 +3782,7 @@ static int io_req_needs_file(struct io_kiocb *req, int fd)
 	case IORING_OP_LINK_TIMEOUT:
 		return 0;
 	case IORING_OP_OPENAT:
+	case IORING_OP_STATX:
 		return fd != -1;
 	default:
 		if (io_req_op_valid(req->opcode))
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index ca436b9d4921..3f45f7c543de 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -35,6 +35,7 @@ struct io_uring_sqe {
 		__u32		accept_flags;
 		__u32		cancel_flags;
 		__u32		open_flags;
+		__u32		statx_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	union {
@@ -81,6 +82,7 @@ enum {
 	IORING_OP_OPENAT,
 	IORING_OP_CLOSE,
 	IORING_OP_FILES_UPDATE,
+	IORING_OP_STATX,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
-- 
2.25.1