Re: [BUG? liburing] io_uring_register_files_update with liburing 2.0 on 5.13.17

[Jens Axboe <axboe@kernel.dk>]

On 9/18/21 5:37 PM, Jens Axboe wrote:
>> and it failed with the same as before...
>>
>> io_uring_register(13, IORING_REGISTER_FILES, [-1, -1, -1, 3, 4, 5, 6, 7, 8,
>> 9, 10, 11, 12, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
>> -1, -1, -1, -1,
>> -1, ...], 32768) = -1 EMFILE (Too many open files)
>>
>> if you want i can debug it for you tomorrow? (in london)
> 
> Nah that's fine, I think it's just because you have other files opened
> too. We bump the cur limit _to_ 'nr', but that leaves no room for anyone
> else. Would be my guess. It works fine for the test case I ran here, but
> your case may be different. Does it work if you just make it:
> 
> rlim.rlim_cur += nr;
> 
> instead?

Specifically, just something like the below incremental. If rlim_cur
_seems_ big enough, leave it alone. If not, add the amount we need to
cur. And don't do any error checking here, let's leave failure to the
kernel.

diff --git a/src/register.c b/src/register.c
index bab42d0..7597ec1 100644
--- a/src/register.c
+++ b/src/register.c
@@ -126,9 +126,7 @@ static int bump_rlimit_nofile(unsigned nr)
 	if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
 		return -errno;
 	if (rlim.rlim_cur < nr) {
-		if (nr > rlim.rlim_max)
-			return -EMFILE;
-		rlim.rlim_cur = nr;
+		rlim.rlim_cur += nr;
 		setrlimit(RLIMIT_NOFILE, &rlim);
 	}
 

-- 
Jens Axboe