Hi, Caveat - this series is very much an RFC. Not because I don't think the idea is sound (and the way it should be done), but because the series itself is not very clean. It should be split a bit more. So just look at the final result, not as much the individual patches just yet. For a full explanation of the goal of the series, see patch #3. tldr is that our currently rsrc node handling can block freeing of resources for an indeterminite amount of time, which is very unfortunate for potentially long lived request. For example, networked workloads and using fixed files, where a previously long lived socket has the full resource tables of the entire ring pinned. That can lead to files being held open for a very long time. This series handles the resource nodes separately, so a request pins just the resources it needs, and only for the duration of that request. In doing so, it also unifies how these resources are tracked. As it stands, the current kernel duplicates state across user_bufs and buf_data, and ditto for the file_table and file_data. Not only is some of it duplicated (like the node arrays), it also needs to alloc and copy the tags that are potentially associated with the resource. With the unification, state is only in one spot for each type of resource, and tags are handled at registration time rather than needing to be retained for the duration of the resource. As with cleaning up of structures, it also shrinks io_ring_ctx by 64b (should be more, it adds holes too in spots), and the actual resource node goes from needing 48b and 16b of put info, to 40b. Lightly tested - it passes the liburing test suite, and doesn't leak any memory. And it removes a net of about 250 lines of code, as can be seen from the diffstat below. In my opinion it's also easier to follow. Can also be found here: https://git.kernel.dk/cgit/linux/log/?h=io_uring-rsrc include/linux/io_uring_types.h | 25 +- io_uring/cancel.c | 4 +- io_uring/fdinfo.c | 10 +- io_uring/filetable.c | 71 ++-- io_uring/filetable.h | 26 +- io_uring/io_uring.c | 51 +-- io_uring/msg_ring.c | 4 +- io_uring/net.c | 15 +- io_uring/notif.c | 3 +- io_uring/opdef.c | 2 + io_uring/register.c | 3 +- io_uring/rsrc.c | 586 +++++++++++---------------------- io_uring/rsrc.h | 97 +++--- io_uring/rw.c | 12 +- io_uring/splice.c | 42 ++- io_uring/splice.h | 1 + io_uring/uring_cmd.c | 16 +- 17 files changed, 366 insertions(+), 602 deletions(-) -- Jens Axboe
