[PATCH 2/2] io_uring: add support for ftruncate

[Tony Solomonik <tony.solomonik@gmail.com>]

Like truncate, ftruncate should also be supported in io_uring.
---
 include/uapi/linux/io_uring.h |  1 +
 io_uring/opdef.c              |  7 +++++++
 io_uring/truncate.c           | 37 +++++++++++++++++++++++++++++++++++
 io_uring/truncate.h           |  3 +++
 4 files changed, 48 insertions(+)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 513f31ee8ce9..8ebaf667c07d 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -254,6 +254,7 @@ enum io_uring_op {
 	IORING_OP_FUTEX_WAKE,
 	IORING_OP_FUTEX_WAITV,
 	IORING_OP_TRUNCATE,
+	IORING_OP_FTRUNCATE,
 
 	/* this goes last, obviously */
 	IORING_OP_LAST,
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 60827099e244..88054f3df83c 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -474,6 +474,10 @@ const struct io_issue_def io_issue_defs[] = {
 		.prep			= io_truncate_prep,
 		.issue			= io_truncate,
 	},
+	[IORING_OP_FTRUNCATE] = {
+		.prep			= io_ftruncate_prep,
+		.issue			= io_ftruncate,
+	},
 };
 
 const struct io_cold_def io_cold_defs[] = {
@@ -712,6 +716,9 @@ const struct io_cold_def io_cold_defs[] = {
 	[IORING_OP_TRUNCATE] = {
 		.name			= "TRUNCATE",
 	},
+	[IORING_OP_FTRUNCATE] = {
+		.name			= "FTRUNCATE",
+	},
 };
 
 const char *io_uring_get_opcode(u8 opcode)
diff --git a/io_uring/truncate.c b/io_uring/truncate.c
index 82648b2fbc7e..e31d28a478d2 100644
--- a/io_uring/truncate.c
+++ b/io_uring/truncate.c
@@ -21,6 +21,12 @@ struct io_trunc {
 	loff_t				len;
 };
 
+struct io_ftrunc {
+	struct file			*file;
+	int				dfd;
+	loff_t				len;
+};
+
 int io_truncate_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_trunc *tr = io_kiocb_to_cmd(req, struct io_trunc);
@@ -51,3 +57,34 @@ int io_truncate(struct io_kiocb *req, unsigned int issue_flags)
 	io_req_set_res(req, ret, 0);
 	return IOU_OK;
 }
+
+int io_ftruncate_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_ftrunc *ft = io_kiocb_to_cmd(req, struct io_ftrunc);
+
+	if (sqe->off || sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
+		return -EBADF;
+
+	ft->dfd = READ_ONCE(sqe->fd);
+	ft->len = READ_ONCE(sqe->len);
+
+	req->flags |= REQ_F_NEED_CLEANUP;
+	req->flags |= REQ_F_FORCE_ASYNC;
+	return 0;
+}
+
+int io_ftruncate(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ftrunc *ft = io_kiocb_to_cmd(req, struct io_ftrunc);
+	int ret;
+
+	WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);
+
+	ret = do_sys_ftruncate(ft->dfd, ft->len, 1);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	io_req_set_res(req, ret, 0);
+	return IOU_OK;
+}
diff --git a/io_uring/truncate.h b/io_uring/truncate.h
index ab17cb9acc90..a9fc20b5f926 100644
--- a/io_uring/truncate.h
+++ b/io_uring/truncate.h
@@ -2,3 +2,6 @@
 
 int io_truncate_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_truncate(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_ftruncate_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_ftruncate(struct io_kiocb *req, unsigned int issue_flags);
-- 
2.34.1