On 2/23/20 7:58 AM, Jens Axboe wrote:
> On 2/23/20 7:49 AM, Jens Axboe wrote:
>>> Anyway, creds handling is too scattered across the code, and this do a
>>> lot of useless refcounting and bouncing. It's better to find it a
>>> better place in the near future.
>>
>> I think a good cleanup on top of this would be to move the personality
>> lookup to io_req_defer_prep(), and kill it from io_submit_sqe(). Now
>> __io_issue_sqe() does the right thing, and it'll just fall out nicely
>> with that as far as I can tell.
>>
>> Care to send a patch for that?
>
> Since we also need it for non-deferral, how about just leaving the
> lookup in there and removing the assignment? That means we only do that
> juggling in one spot, which makes more sense. I think this should just
> be folded into the previous patch.
Tested, we need a ref grab on the creds when assigning since we're
dropped at the other end.
diff --git a/fs/io_uring.c b/fs/io_uring.c
index cead1a0602b4..d83f113f22fd 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4923,7 +4923,6 @@ static inline void io_queue_link_head(struct io_kiocb *req)
static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct io_submit_state *state, struct io_kiocb **link)
{
- const struct cred *old_creds = NULL;
struct io_ring_ctx *ctx = req->ctx;
unsigned int sqe_flags;
int ret, id;
@@ -4938,14 +4937,12 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
id = READ_ONCE(sqe->personality);
if (id) {
- const struct cred *personality_creds;
-
- personality_creds = idr_find(&ctx->personality_idr, id);
- if (unlikely(!personality_creds)) {
+ req->work.creds = idr_find(&ctx->personality_idr, id);
+ if (unlikely(!req->work.creds)) {
ret = -EINVAL;
goto err_req;
}
- old_creds = override_creds(personality_creds);
+ get_cred(req->work.creds);
}
/* same numerical values with corresponding REQ_F_*, safe to copy */
@@ -4957,8 +4954,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
err_req:
io_cqring_add_event(req, ret);
io_double_put_req(req);
- if (old_creds)
- revert_creds(old_creds);
return false;
}
@@ -5019,8 +5014,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
}
}
- if (old_creds)
- revert_creds(old_creds);
return true;
}
--
Jens Axboe
