queue-6.6/ublk-complete-command-synchronously-on-error.patch

From 5df6646864caef2931e25351fc4aa64f7b47c6cc Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 25 Feb 2025 14:24:55 -0700
Subject: ublk: complete command synchronously on error

From: Caleb Sander Mateos <csander@purestorage.com>

[ Upstream commit 603f9be21c1894e462416e3324962d6c9c2b95f8 ]

In case of an error, ublk's ->uring_cmd() functions currently return
-EIOCBQUEUED and immediately call io_uring_cmd_done(). -EIOCBQUEUED and
io_uring_cmd_done() are intended for asynchronous completions. For
synchronous completions, the ->uring_cmd() function can just return the
negative return code directly. This skips io_uring_cmd_del_cancelable(),
and deferring the completion to task work. So return the error code
directly from __ublk_ch_uring_cmd() and ublk_ctrl_uring_cmd().

Update ublk_ch_uring_cmd_cb(), which currently ignores the return value
from __ublk_ch_uring_cmd(), to call io_uring_cmd_done() for synchronous
completions.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250225212456.2902549-1-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stable-dep-of: c6a45ee7607d ("ublk: prevent invalid access with DEBUG")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/ublk_drv.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 6419f304fa5e2..88d566f0ffa64 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1821,10 +1821,9 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
 	return -EIOCBQUEUED;
 
  out:
-	io_uring_cmd_done(cmd, ret, 0, issue_flags);
 	pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
 			__func__, cmd_op, tag, ret, io->flags);
-	return -EIOCBQUEUED;
+	return ret;
 }
 
 static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
@@ -1880,7 +1879,10 @@ static inline int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
 static void ublk_ch_uring_cmd_cb(struct io_uring_cmd *cmd,
 		unsigned int issue_flags)
 {
-	ublk_ch_uring_cmd_local(cmd, issue_flags);
+	int ret = ublk_ch_uring_cmd_local(cmd, issue_flags);
+
+	if (ret != -EIOCBQUEUED)
+		io_uring_cmd_done(cmd, ret, 0, issue_flags);
 }
 
 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
@@ -2948,10 +2950,9 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
 	if (ub)
 		ublk_put_device(ub);
  out:
-	io_uring_cmd_done(cmd, ret, 0, issue_flags);
 	pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
 			__func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
-	return -EIOCBQUEUED;
+	return ret;
 }
 
 static const struct file_operations ublk_ctl_fops = {
-- 
2.51.0