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;
