From ad5f2e2908c9b79a86529281a48e94d644d43dc7 Mon Sep 17 00:00:00 2001 From: Caleb Sander Mateos Date: Wed, 28 Jan 2026 13:56:34 -0700 Subject: [PATCH] ublk: restore auto buf unregister refcount optimization Commit 1ceeedb59749 ("ublk: optimize UBLK_IO_UNREGISTER_IO_BUF on daemon task") optimized ublk request buffer unregistration to use a non-atomic reference count decrement when performed on the ublk_io's daemon task. The optimization applied to auto buffer unregistration, which happens as part of handling UBLK_IO_COMMIT_AND_FETCH_REQ on the daemon task. However, commit b749965edda8 ("ublk: remove ublk_commit_and_fetch()") reordered the ublk_sub_req_ref() for the completed request before the io_buffer_unregister_bvec() call. As a result, task_registered_buffers is already 0 when io_buffer_unregister_bvec() calls ublk_io_release() and the non-atomic refcount optimization doesn't apply. Move the io_buffer_unregister_bvec() call back to before ublk_need_complete_req() to restore the reference counting optimization. Signed-off-by: Caleb Sander Mateos Fixes: b749965edda8 ("ublk: remove ublk_commit_and_fetch()") Reviewed-by: Ming Lei Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 8a5a6ba29a1de..5efaf53261cec 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -3334,11 +3334,11 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, io->res = result; req = ublk_fill_io_cmd(io, cmd); ret = ublk_config_io_buf(ub, io, cmd, addr, &buf_idx); + if (buf_idx != UBLK_INVALID_BUF_IDX) + io_buffer_unregister_bvec(cmd, buf_idx, issue_flags); compl = ublk_need_complete_req(ub, io); /* can't touch 'ublk_io' any more */ - if (buf_idx != UBLK_INVALID_BUF_IDX) - io_buffer_unregister_bvec(cmd, buf_idx, issue_flags); if (req_op(req) == REQ_OP_ZONE_APPEND) req->__sector = addr; if (compl) -- 2.47.3