This is a note to let you know that I've just added the patch titled block: ublk: check IO buffer based on flag need_get_data to the 6.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: block-ublk-check-io-buffer-based-on-flag-need_get_da.patch and it can be found in the queue-6.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit b6ae1275350df3bf9fb6110e6f7592ef61a25d6e Author: Liu Xiaodong <xiaodong.liu@xxxxxxxxx> Date: Fri Feb 10 09:13:56 2023 -0500 block: ublk: check IO buffer based on flag need_get_data [ Upstream commit 2f1e07dda1e1310873647abc40bbc49eaf3b10e3 ] Currently, uring_cmd with UBLK_IO_FETCH_REQ or UBLK_IO_COMMIT_AND_FETCH_REQ is always checked whether userspace server has provided IO buffer even flag UBLK_F_NEED_GET_DATA is configured. This is a excessive check. If UBLK_F_NEED_GET_DATA is configured, FETCH_RQ doesn't need to provide IO buffer; COMMIT_AND_FETCH_REQ also doesn't need to do that if the IO type is not READ. Check ub_cmd->addr together with ublk_need_get_data() and IO type in ublk_ch_uring_cmd(). With this fix, userspace server doesn't need to preserve buffers for every ublk_io when flag UBLK_F_NEED_GET_DATA is configured, in order to save memory. Signed-off-by: Liu Xiaodong <xiaodong.liu@xxxxxxxxx> Fixes: c86019ff75c1 ("ublk_drv: add support for UBLK_IO_NEED_GET_DATA") Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230210141356.112321-1-xiaodong.liu@xxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 450bd54fd0061..4aec9be0ab77e 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1206,6 +1206,7 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) u32 cmd_op = cmd->cmd_op; unsigned tag = ub_cmd->tag; int ret = -EINVAL; + struct request *req; pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n", __func__, cmd->cmd_op, ub_cmd->q_id, tag, @@ -1256,8 +1257,8 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) */ if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV) goto out; - /* FETCH_RQ has to provide IO buffer */ - if (!ub_cmd->addr) + /* FETCH_RQ has to provide IO buffer if NEED GET DATA is not enabled */ + if (!ub_cmd->addr && !ublk_need_get_data(ubq)) goto out; io->cmd = cmd; io->flags |= UBLK_IO_FLAG_ACTIVE; @@ -1266,8 +1267,12 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) ublk_mark_io_ready(ub, ubq); break; case UBLK_IO_COMMIT_AND_FETCH_REQ: - /* FETCH_RQ has to provide IO buffer */ - if (!ub_cmd->addr) + req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag); + /* + * COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is + * not enabled or it is Read IO. + */ + if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ)) goto out; if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)) goto out;