qemu-kvm/kvm-blkdebug-Add-delay-ns-option.patch

From 6386e658adc798b2af7400a53941523d21dd581d Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Tue, 21 Apr 2026 18:11:26 +0200
Subject: [PATCH 01/52] blkdebug: Add 'delay-ns' option

RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 503: ide: Fix deadlock between TRIM and drain
RH-Jira: RHEL-121686
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [1/7] b6ade079279909f3b38a03fc710c1f0ebd475915 (kmwolf/centos-qemu-kvm)

Sometimes reproducing a problem for debugging involves slow I/O, so
let's add something to blkdebug to make I/O slow when we need it. This
can be used either together with an error so that the request fails
after the delay, or with errno=0, which allows the request to succeed
after the delay.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20260421161132.99878-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit d5e4090177ad382e01084a1594a1a60a69f4c1cd)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/blkdebug.c     | 15 ++++++++++++++-
 qapi/block-core.json |  4 ++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/block/blkdebug.c b/block/blkdebug.c
index c54aee0c84..8954fc2977 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -95,6 +95,7 @@ typedef struct BlkdebugRule {
             int immediately;
             int once;
             int64_t offset;
+            int64_t delay_ns;
         } inject;
         struct {
             int new_state;
@@ -144,6 +145,10 @@ static QemuOptsList inject_error_opts = {
             .name = "immediately",
             .type = QEMU_OPT_BOOL,
         },
+        {
+            .name = "delay-ns",
+            .type = QEMU_OPT_NUMBER,
+        },
         { /* end of list */ }
     },
 };
@@ -216,6 +221,8 @@ static int add_rule(void *opaque, QemuOpts *opts, Error **errp)
         rule->options.inject.once  = qemu_opt_get_bool(opts, "once", 0);
         rule->options.inject.immediately =
             qemu_opt_get_bool(opts, "immediately", 0);
+        rule->options.inject.delay_ns =
+            qemu_opt_get_number(opts, "delay-ns", 0);
         sector = qemu_opt_get_number(opts, "sector", -1);
         rule->options.inject.offset =
             sector == -1 ? -1 : sector * BDRV_SECTOR_SIZE;
@@ -594,6 +601,7 @@ static int coroutine_fn rule_check(BlockDriverState *bs, uint64_t offset,
     BlkdebugRule *rule = NULL;
     int error;
     bool immediately;
+    int64_t delay_ns;
 
     qemu_mutex_lock(&s->lock);
     QSIMPLEQ_FOREACH(rule, &s->active_rules, active_next) {
@@ -608,13 +616,14 @@ static int coroutine_fn rule_check(BlockDriverState *bs, uint64_t offset,
         }
     }
 
-    if (!rule || !rule->options.inject.error) {
+    if (!rule) {
         qemu_mutex_unlock(&s->lock);
         return 0;
     }
 
     immediately = rule->options.inject.immediately;
     error = rule->options.inject.error;
+    delay_ns  = rule->options.inject.delay_ns;
 
     if (rule->options.inject.once) {
         QSIMPLEQ_REMOVE(&s->active_rules, rule, BlkdebugRule, active_next);
@@ -622,6 +631,10 @@ static int coroutine_fn rule_check(BlockDriverState *bs, uint64_t offset,
     }
 
     qemu_mutex_unlock(&s->lock);
+
+    if (delay_ns) {
+        qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, delay_ns);
+    }
     if (!immediately) {
         aio_co_schedule(qemu_get_current_aio_context(), qemu_coroutine_self());
         qemu_coroutine_yield();
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 0236936139..6cf8c1b9c8 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3909,6 +3909,9 @@
 #
 # @errno: error identifier (errno) to be returned; defaults to EIO
 #
+# @delay-ns: request delay before completion in nanoseconds
+#            (default: 0, since: 11.1)
+#
 # @sector: specifies the sector index which has to be affected in
 #     order to actually trigger the event; defaults to "any sector"
 #
@@ -3924,6 +3927,7 @@
             '*state': 'int',
             '*iotype': 'BlkdebugIOType',
             '*errno': 'int',
+            '*delay-ns': 'int',
             '*sector': 'int',
             '*once': 'bool',
             '*immediately': 'bool' } }
-- 
2.52.0