[PATCH 3/6] io_uring: add support for IORING_OP_OPENAT

Jens Axboe
2020-01-07T17:00:41Z

This works just like openat(2), except it can be performed async. For
the normal case of a non-blocking path lookup this will complete
inline. If we have to do IO to perform the open, it'll be done from
async context.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
fs/io_uring.c | 107 +++++++++++++++++++++++++++++++++-
include/uapi/linux/io_uring.h | 2 +
2 files changed, 107 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1822bf9aba12..53ff67ab5c4b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -70,6 +70,8 @@
#include <linux/sizes.h>
#include <linux/hugetlb.h>
#include <linux/highmem.h>
+#include <linux/namei.h>
+#include <linux/fsnotify.h>

#define CREATE_TRACE_POINTS
#include <trace/events/io_uring.h>
@@ -353,6 +355,15 @@ struct io_sr_msg {
int msg_flags;
};

+struct io_open {
+ struct file *file;
+ int dfd;
+ umode_t mode;
+ const char __user *fname;
+ struct filename *filename;
+ int flags;
+};
+
struct io_async_connect {
struct sockaddr_storage address;
};
@@ -371,12 +382,17 @@ struct io_async_rw {
ssize_t size;
};

+struct io_async_open {
+ struct filename *filename;
+};
+
struct io_async_ctx {
union {
struct io_async_rw rw;
struct io_async_msghdr msg;
struct io_async_connect connect;
struct io_timeout_data timeout;
+ struct io_async_open open;
};
};

@@ -397,6 +413,7 @@ struct io_kiocb {
struct io_timeout timeout;
struct io_connect connect;
struct io_sr_msg sr_msg;
+ struct io_open open;
};

struct io_async_ctx *io;
@@ -2135,6 +2152,79 @@ static int io_fallocate(struct io_kiocb *req, struct io_kiocb **nxt,
return 0;
}

+static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ int ret;
+
+ if (sqe->ioprio || sqe->buf_index)
+ return -EINVAL;
+
+ req->open.dfd = READ_ONCE(sqe->fd);
+ req->open.mode = READ_ONCE(sqe->len);
+ req->open.fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
+ req->open.flags = READ_ONCE(sqe->open_flags);
+
+ req->open.filename = getname(req->open.fname);
+ if (IS_ERR(req->open.filename)) {
+ ret = PTR_ERR(req->open.filename);
+ req->open.filename = NULL;
+ return ret;
+ }
+
+ return 0;
+}
+
+static void io_openat_async(struct io_wq_work **workptr)
+{
+ struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+ struct filename *filename = req->open.filename;
+
+ io_wq_submit_work(workptr);
+ putname(filename);
+}
+
+static int io_openat(struct io_kiocb *req, struct io_kiocb **nxt,
+ bool force_nonblock)
+{
+ struct open_flags op;
+ struct open_how how;
+ struct file *file;
+ int ret;
+
+ how = build_open_how(req->open.flags, req->open.mode);
+ ret = build_open_flags(&how, &op);
+ if (ret)
+ goto err;
+ if (force_nonblock)
+ op.lookup_flags |= LOOKUP_NONBLOCK;
+
+ ret = get_unused_fd_flags(how.flags);
+ if (ret < 0)
+ goto err;
+
+ file = do_filp_open(req->open.dfd, req->open.filename, &op);
+ if (IS_ERR(file)) {
+ put_unused_fd(ret);
+ ret = PTR_ERR(file);
+ if (ret == -EAGAIN) {
+ req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+ req->work.func = io_openat_async;
+ return -EAGAIN;
+ }
+ } else {
+ fsnotify_open(file);
+ fd_install(ret, file);
+ }
+err:
+ if (!io_wq_current_is_worker())
+ putname(req->open.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_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_ring_ctx *ctx = req->ctx;
@@ -3160,6 +3250,9 @@ static int io_req_defer_prep(struct io_kiocb *req,
case IORING_OP_FALLOCATE:
ret = io_fallocate_prep(req, sqe);
break;
+ case IORING_OP_OPENAT:
+ ret = io_openat_prep(req, sqe);
+ break;
default:
printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
req->opcode);
@@ -3322,6 +3415,14 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
ret = io_fallocate(req, nxt, force_nonblock);
break;
+ case IORING_OP_OPENAT:
+ if (sqe) {
+ ret = io_openat_prep(req, sqe);
+ if (ret)
+ break;
+ }
+ ret = io_openat(req, nxt, force_nonblock);
+ break;
default:
ret = -EINVAL;
break;
@@ -3403,7 +3504,7 @@ static bool io_req_op_valid(int op)
return op >= IORING_OP_NOP && op < IORING_OP_LAST;
}

-static int io_req_needs_file(struct io_kiocb *req)
+static int io_req_needs_file(struct io_kiocb *req, int fd)
{
switch (req->opcode) {
case IORING_OP_NOP:
@@ -3413,6 +3514,8 @@ static int io_req_needs_file(struct io_kiocb *req)
case IORING_OP_ASYNC_CANCEL:
case IORING_OP_LINK_TIMEOUT:
return 0;
+ case IORING_OP_OPENAT:
+ return fd != -1;
default:
if (io_req_op_valid(req->opcode))
return 1;
@@ -3442,7 +3545,7 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
if (flags & IOSQE_IO_DRAIN)
req->flags |= REQ_F_IO_DRAIN;

- ret = io_req_needs_file(req);
+ ret = io_req_needs_file(req, fd);
if (ret <= 0)
return ret;

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index bdbe2b130179..02af580754ce 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -34,6 +34,7 @@ struct io_uring_sqe {
__u32 timeout_flags;
__u32 accept_flags;
__u32 cancel_flags;
+ __u32 open_flags;
};
__u64 user_data; /* data to be passed back at completion time */
union {
@@ -77,6 +78,7 @@ enum {
IORING_OP_LINK_TIMEOUT,
IORING_OP_CONNECT,
IORING_OP_FALLOCATE,
+ IORING_OP_OPENAT,

/* this goes last, obviously */
IORING_OP_LAST,
--
2.24.1