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authorJens Axboe <axboe@kernel.dk>2020-03-03 15:45:36 -0700
committerJens Axboe <axboe@kernel.dk>2020-03-03 20:04:48 -0700
commit843c96d0be7117bd89fcc9d9ed74f78130c2e527 (patch)
tree14a66f81faa72704843df69cb21b63719b6fa08f
parent14309739929df6d23f2594dd19bc6784a2a3f7fd (diff)
io_uring: test patch for fd passingio_uring-fd-pass
This allows a chain link to set ->fd to IOSQE_FD_LAST_OPEN, which will then be turned into the results from the last open (or accept) request in the chain. If no open has been done, this isn't valid and the request will be errored with -EBADF. With this, we can define chains of open+read+close, where the read and close part can work on the fd instantiated by the open request. Totally a work in progress, POC so far. Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c56
-rw-r--r--include/uapi/linux/io_uring.h6
2 files changed, 58 insertions, 4 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 047bee3e8fdb..176c0ba68f45 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -511,6 +511,7 @@ enum {
REQ_F_OVERFLOW_BIT,
REQ_F_POLLED_BIT,
REQ_F_BUFFER_SELECTED_BIT,
+ REQ_F_OPEN_FD_BIT,
/* not a real bit, just to check we're not overflowing the space */
__REQ_F_LAST_BIT,
@@ -562,6 +563,8 @@ enum {
REQ_F_POLLED = BIT(REQ_F_POLLED_BIT),
/* buffer already selected */
REQ_F_BUFFER_SELECTED = BIT(REQ_F_BUFFER_SELECTED_BIT),
+ /* use chain previous open fd */
+ REQ_F_OPEN_FD = BIT(REQ_F_OPEN_FD_BIT),
};
struct async_poll {
@@ -600,6 +603,9 @@ struct io_kiocb {
bool needs_fixed_file;
u8 opcode;
+ int last_open_fd;
+ struct file *last_open_file;
+
struct io_ring_ctx *ctx;
struct list_head list;
unsigned int flags;
@@ -1344,7 +1350,7 @@ static inline void io_put_file(struct io_kiocb *req, struct file *file,
{
if (fixed)
percpu_ref_put(&req->ctx->file_data->refs);
- else
+ else if (!(req->flags & REQ_F_OPEN_FD))
fput(file);
}
@@ -1487,6 +1493,14 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
list_del_init(&req->link_list);
if (!list_empty(&nxt->link_list))
nxt->flags |= REQ_F_LINK;
+ if (nxt->flags & REQ_F_OPEN_FD) {
+ WARN_ON_ONCE(nxt->file);
+ if (unlikely(!req->last_open_file))
+ nxt->flags |= REQ_F_FAIL_LINK;
+ nxt->last_open_file = req->last_open_file;
+ nxt->last_open_fd = req->last_open_fd;
+ nxt->file = req->last_open_file;
+ }
*nxtptr = nxt;
break;
}
@@ -2965,8 +2979,8 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
static int io_openat2(struct io_kiocb *req, bool force_nonblock)
{
+ struct file *file = NULL;
struct open_flags op;
- struct file *file;
int ret;
if (force_nonblock)
@@ -2991,8 +3005,12 @@ static int io_openat2(struct io_kiocb *req, bool force_nonblock)
err:
putname(req->open.filename);
req->flags &= ~REQ_F_NEED_CLEANUP;
- if (ret < 0)
+ if (ret < 0) {
req_set_fail_links(req);
+ } else if (req->flags & REQ_F_LINK) {
+ req->last_open_file = file;
+ req->last_open_fd = ret;
+ }
io_cqring_add_event(req, ret);
io_put_req(req);
return 0;
@@ -3410,6 +3428,14 @@ static int io_close(struct io_kiocb *req, bool force_nonblock)
{
int ret;
+ if (req->flags & REQ_F_OPEN_FD) {
+ if (req->close.fd != IOSQE_FD_LAST_OPEN)
+ return -EBADF;
+ req->close.fd = req->last_open_fd;
+ req->last_open_file = NULL;
+ req->last_open_fd = -1;
+ }
+
if (req->file->f_op == &io_uring_fops ||
req->close.fd == req->ctx->ring_fd)
return -EBADF;
@@ -3963,8 +3989,14 @@ static int __io_accept(struct io_kiocb *req, bool force_nonblock)
return -EAGAIN;
if (ret == -ERESTARTSYS)
ret = -EINTR;
- if (ret < 0)
+ if (ret < 0) {
req_set_fail_links(req);
+ } else if (req->flags & REQ_F_LINK) {
+ rcu_read_lock();
+ req->last_open_file = fcheck_files(current->files, ret);
+ rcu_read_unlock();
+ req->last_open_fd = ret;
+ }
io_cqring_add_event(req, ret);
io_put_req(req);
return 0;
@@ -5000,6 +5032,9 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct io_ring_ctx *ctx = req->ctx;
int ret;
+ if ((req->flags & REQ_F_OPEN_FD) && !req->file)
+ return -EBADF;
+
switch (req->opcode) {
case IORING_OP_NOP:
ret = io_nop(req);
@@ -5336,6 +5371,14 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
return 0;
fixed = (flags & IOSQE_FIXED_FILE);
+ if (fd == IOSQE_FD_LAST_OPEN) {
+ if (fixed)
+ return -EBADF;
+ req->flags |= REQ_F_OPEN_FD;
+ req->file = NULL;
+ return 0;
+ }
+
if (unlikely(!fixed && req->needs_fixed_file))
return -EBADF;
@@ -5647,6 +5690,9 @@ err_req:
trace_io_uring_link(ctx, req, head);
list_add_tail(&req->link_list, &head->link_list);
+ req->last_open_fd = -1;
+ req->last_open_file = NULL;
+
/* last request of a link, enqueue the link */
if (!(sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK))) {
io_queue_link_head(head);
@@ -5659,6 +5705,8 @@ err_req:
}
if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) {
req->flags |= REQ_F_LINK;
+ req->last_open_fd = -1;
+ req->last_open_file = NULL;
INIT_LIST_HEAD(&req->link_list);
ret = io_req_defer_prep(req, sqe);
if (ret)
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index cef4c0c0f26b..3ee4ba230c82 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -86,6 +86,12 @@ enum {
#define IOSQE_BUFFER_SELECT (1U << IOSQE_BUFFER_SELECT_BIT)
/*
+ * 'magic' ->fd values don't point to a real fd, but rather define how fds
+ * can be inherited through links in a chain
+ */
+#define IOSQE_FD_LAST_OPEN (-4096) /* previous result is fd */
+
+/*
* io_uring_setup() flags
*/
#define IORING_SETUP_IOPOLL (1U << 0) /* io_context is polled */