In some scenarios, we want to modify the blk timeout, but the
blk timeout is a hard-code constant, the default value is 30s,
so this patch changes blk timeout to a variable that can be
controlled via sysctl.

Signed-off-by: lwk <lwk111111@126.com>

	modified:   block/blk-mq.c
	modified:   drivers/block/Makefile
	new file:   drivers/block/blk_sysctl.c
	modified:   include/linux/blkdev.h
---
 block/blk-mq.c             |  2 +-
 drivers/block/Makefile     |  1 +
 drivers/block/blk_sysctl.c | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h     |  1 +
 4 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 drivers/block/blk_sysctl.c

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 40490ac88..2a087b6b8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4537,7 +4537,7 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 		goto err_hctxs;
 
 	INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
-	blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
+	blk_queue_rq_timeout(q, set->timeout ? set->timeout : sysctl_blk_timeout);
 
 	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 1105a2d4f..544e6b6b5 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -12,6 +12,7 @@ ccflags-y				+= -I$(src)
 obj-$(CONFIG_BLK_DEV_RUST_NULL) += rnull_mod.o
 rnull_mod-y := rnull.o
 
+obj-$(CONFIG_SYSCTL)        += blk_sysctl.o
 obj-$(CONFIG_MAC_FLOPPY)	+= swim3.o
 obj-$(CONFIG_BLK_DEV_SWIM)	+= swim_mod.o
 obj-$(CONFIG_BLK_DEV_FD)	+= floppy.o
diff --git a/drivers/block/blk_sysctl.c b/drivers/block/blk_sysctl.c
new file mode 100644
index 000000000..f8f96ad12
--- /dev/null
+++ b/drivers/block/blk_sysctl.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * blk_sysctl.c: sysctl interface to block subsystem.
+ *
+ * Begun Nov 10, 2025, lwk.
+ * Added /proc/sys/block directory entry
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sysctl.h>
+#include <linux/blkdev.h>
+
+
+unsigned int sysctl_blk_timeout = 30;
+
+static struct ctl_table blk_table_sysctls[] = {
+	{
+		.procname		= "blk_timeout",
+		.data			= &sysctl_blk_timeout,
+		.maxlen			= sizeof(int),
+		.mode			= 0644,
+		.proc_handler	= proc_dointvec
+	},
+	{}
+};
+
+static __init int sysctl_blk_init(void)
+{
+#ifdef CONFIG_SYSCTL
+	register_sysctl_init("block", blk_table_sysctls);
+#endif
+
+	return 0;
+}
+
+__initcall(sysctl_blk_init);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d37751789..51802d5f7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -42,6 +42,7 @@ struct blk_queue_stats;
 struct blk_stat_callback;
 struct blk_crypto_profile;
 
+extern unsigned int sysctl_blk_timeout;
 extern const struct device_type disk_type;
 extern const struct device_type part_type;
 extern const struct class block_class;
-- 
2.47.3