On 3/11/25 11:40, Sidong Yang wrote:
io_uring_cmd_import_fixed_vec() could be used for using multiple
fixed buffer in uring_cmd callback.
Signed-off-by: Sidong Yang <sidong.yang@xxxxxxxxxx>
---
include/linux/io_uring/cmd.h | 14 ++++++++++++++
io_uring/uring_cmd.c | 29 +++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
index 598cacda4aa3..75cf25c1e730 100644
--- a/include/linux/io_uring/cmd.h
+++ b/include/linux/io_uring/cmd.h
@@ -44,6 +44,13 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
struct io_uring_cmd *ioucmd,
unsigned int issue_flags);
+int io_uring_cmd_import_fixed_vec(const struct iovec __user *uiovec,
+ unsigned long nr_segs, int rw,
+ struct iov_iter *iter,
+ struct io_uring_cmd *ioucmd,
nit: it's better to be the first arg
+ struct iou_vec *iou_vec, bool compat,
Same comment, iou_vec should not be exposed. And why do we
need to pass compat here? Instead of io_is_compat() inside
the helper.
+ unsigned int issue_flags);
+
/*
* Completes the request, i.e. posts an io_uring CQE and deallocates @ioucmd
* and the corresponding io_uring request.
@@ -76,6 +83,13 @@ io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
{
return -EOPNOTSUPP;
}
+int io_uring_cmd_import_fixed_vec(int rw, struct iov_iter *iter,
+ struct io_uring_cmd *ioucmd,
+ struct iou_vec *vec, unsigned nr_iovs,
+ unsigned iovec_off, unsigned int issue_flags)
+{
+ return -EOPNOTSUPP;
+}
static inline void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret,
u64 ret2, unsigned issue_flags)
{
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index de39b602aa82..58e2932f29e7 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -255,6 +255,35 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
}
EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
+int io_uring_cmd_import_fixed_vec(const struct iovec __user *uiovec,
+ unsigned long nr_segs, int rw,
+ struct iov_iter *iter,
+ struct io_uring_cmd *ioucmd,
+ struct iou_vec *iou_vec, bool compat,
+ unsigned int issue_flags)
+{
+ struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
+ struct iovec *iov;
+ int ret;
+
+ iov = iovec_from_user(uiovec, nr_segs, 0, NULL, compat);
+ if (IS_ERR(iov))
+ return PTR_ERR(iov);
That's one allocation
+
+ ret = io_vec_realloc(iou_vec, nr_segs);
That's a second one
+ if (ret) {
+ kfree(iov);
+ return ret;
+ }
+ memcpy(iou_vec->iovec, iov, sizeof(*iov) * nr_segs);
+ kfree(iov);
+
+ ret = io_import_reg_vec(rw, iter, req, iou_vec, iou_vec->nr, 0,
It's slightly out of date, the import side should use io_prep_reg_iovec(),
it abstracts from iovec placement questions.
+ issue_flags);
And there will likely be a 3rd one. That's pretty likely why
performance is not up to expectations, unlike the rw/net
side which cache it to eventually 0 realloctions.
The first one can be easily removed, but it'll need better
abstractions for cmds not to expose iou_vec. Let me think
what would be a good approach here.
--
Pavel Begunkov
