[PATCH v3 2/2] io_uring: add support for ftruncate

Tony Solomonik
2024-01-23T21:19:59Z

Libraries that are built on io_uring currently need to maintain a
separate thread pool implementation when they want to truncate a file.

Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com>
---
include/uapi/linux/io_uring.h | 1 +
io_uring/Makefile | 2 +-
io_uring/opdef.c | 9 +++++++
io_uring/truncate.c | 48 +++++++++++++++++++++++++++++++++++
io_uring/truncate.h | 4 +++
5 files changed, 63 insertions(+), 1 deletion(-)
create mode 100644 io_uring/truncate.c
create mode 100644 io_uring/truncate.h

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index f1c16f817742..be682e000c94 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -253,6 +253,7 @@ enum io_uring_op {
IORING_OP_FUTEX_WAIT,
IORING_OP_FUTEX_WAKE,
IORING_OP_FUTEX_WAITV,
+ IORING_OP_FTRUNCATE,

/* this goes last, obviously */
IORING_OP_LAST,
diff --git a/io_uring/Makefile b/io_uring/Makefile
index e5be47e4fc3b..4f8ed6530a29 100644
--- a/io_uring/Makefile
+++ b/io_uring/Makefile
@@ -8,6 +8,6 @@ obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \
statx.o net.o msg_ring.o timeout.o \
sqpoll.o fdinfo.o tctx.o poll.o \
cancel.o kbuf.o rsrc.o rw.o opdef.o \
- notif.o waitid.o
+ notif.o waitid.o truncate.o
obj-$(CONFIG_IO_WQ) += io-wq.o
obj-$(CONFIG_FUTEX) += futex.o
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 799db44283c7..7830d087d03f 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -35,6 +35,7 @@
#include "rw.h"
#include "waitid.h"
#include "futex.h"
+#include "truncate.h"

static int io_no_issue(struct io_kiocb *req, unsigned int issue_flags)
{
@@ -469,6 +470,11 @@ const struct io_issue_def io_issue_defs[] = {
.prep = io_eopnotsupp_prep,
#endif
},
+ [IORING_OP_FTRUNCATE] = {
+ .needs_file = 1,
+ .prep = io_ftruncate_prep,
+ .issue = io_ftruncate,
+ },
};

const struct io_cold_def io_cold_defs[] = {
@@ -704,6 +710,9 @@ const struct io_cold_def io_cold_defs[] = {
[IORING_OP_FUTEX_WAITV] = {
.name = "FUTEX_WAITV",
},
+ [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
new file mode 100644
index 000000000000..4b48376149f9
--- /dev/null
+++ b/io_uring/truncate.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <linux/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "../fs/internal.h"
+
+#include "io_uring.h"
+#include "truncate.h"
+
+struct io_ftrunc {
+ struct file *file;
+ loff_t len;
+};
+
+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->rw_flags || sqe->addr || sqe->len || sqe->buf_index ||
+ sqe->splice_fd_in || sqe->addr3)
+ return -EINVAL;
+
+ ft->len = READ_ONCE(sqe->off);
+
+ 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 = ftruncate_file(req->file, ft->len, 0);
+
+ io_req_set_res(req, ret, 0);
+ return IOU_OK;
+}
diff --git a/io_uring/truncate.h b/io_uring/truncate.h
new file mode 100644
index 000000000000..ec088293a478
--- /dev/null
+++ b/io_uring/truncate.h
@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
+
+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