124 lines
4.8 KiB
Diff
124 lines
4.8 KiB
Diff
From 261ee33e0e6711fadd3049e4640bb731ee3d44ff Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Mon, 24 Feb 2020 16:57:10 +0000
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Subject: [PATCH 9/9] mirror: Don't let an operation wait for itself
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20200224165710.4830-3-kwolf@redhat.com>
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Patchwork-id: 94045
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O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH 2/2] mirror: Don't let an operation wait for itself
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Bugzilla: 1794692
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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mirror_wait_for_free_in_flight_slot() just picks a random operation to
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wait for. However, when mirror_co_read() waits for free slots, its
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MirrorOp is already in s->ops_in_flight, so if not enough slots are
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immediately available, an operation can end up waiting for itself to
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complete, which results in a hang.
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Fix this by passing the current MirrorOp and skipping this operation
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when picking an operation to wait for.
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Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1794692
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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(cherry picked from commit 7e6c4ff792734e196c8ca82564c56b5e7c6288ca)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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block/mirror.c | 21 ++++++++++++---------
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1 file changed, 12 insertions(+), 9 deletions(-)
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diff --git a/block/mirror.c b/block/mirror.c
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index 8959e42..cacbc70 100644
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--- a/block/mirror.c
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+++ b/block/mirror.c
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@@ -283,11 +283,14 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset,
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}
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static inline void coroutine_fn
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-mirror_wait_for_any_operation(MirrorBlockJob *s, bool active)
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+mirror_wait_for_any_operation(MirrorBlockJob *s, MirrorOp *self, bool active)
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{
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MirrorOp *op;
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QTAILQ_FOREACH(op, &s->ops_in_flight, next) {
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+ if (self == op) {
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+ continue;
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+ }
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/* Do not wait on pseudo ops, because it may in turn wait on
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* some other operation to start, which may in fact be the
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* caller of this function. Since there is only one pseudo op
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@@ -302,10 +305,10 @@ mirror_wait_for_any_operation(MirrorBlockJob *s, bool active)
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}
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static inline void coroutine_fn
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-mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s)
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+mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s, MirrorOp *self)
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{
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/* Only non-active operations use up in-flight slots */
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- mirror_wait_for_any_operation(s, false);
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+ mirror_wait_for_any_operation(s, self, false);
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}
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/* Perform a mirror copy operation.
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@@ -348,7 +351,7 @@ static void coroutine_fn mirror_co_read(void *opaque)
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while (s->buf_free_count < nb_chunks) {
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trace_mirror_yield_in_flight(s, op->offset, s->in_flight);
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- mirror_wait_for_free_in_flight_slot(s);
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+ mirror_wait_for_free_in_flight_slot(s, op);
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}
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/* Now make a QEMUIOVector taking enough granularity-sized chunks
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@@ -555,7 +558,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
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while (s->in_flight >= MAX_IN_FLIGHT) {
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trace_mirror_yield_in_flight(s, offset, s->in_flight);
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- mirror_wait_for_free_in_flight_slot(s);
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+ mirror_wait_for_free_in_flight_slot(s, pseudo_op);
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}
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if (s->ret < 0) {
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@@ -609,7 +612,7 @@ static void mirror_free_init(MirrorBlockJob *s)
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static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s)
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{
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while (s->in_flight > 0) {
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- mirror_wait_for_free_in_flight_slot(s);
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+ mirror_wait_for_free_in_flight_slot(s, NULL);
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}
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}
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@@ -794,7 +797,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
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if (s->in_flight >= MAX_IN_FLIGHT) {
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trace_mirror_yield(s, UINT64_MAX, s->buf_free_count,
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s->in_flight);
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- mirror_wait_for_free_in_flight_slot(s);
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+ mirror_wait_for_free_in_flight_slot(s, NULL);
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continue;
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}
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@@ -947,7 +950,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
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/* Do not start passive operations while there are active
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* writes in progress */
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while (s->in_active_write_counter) {
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- mirror_wait_for_any_operation(s, true);
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+ mirror_wait_for_any_operation(s, NULL, true);
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}
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if (s->ret < 0) {
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@@ -973,7 +976,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
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if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 ||
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(cnt == 0 && s->in_flight > 0)) {
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trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight);
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- mirror_wait_for_free_in_flight_slot(s);
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+ mirror_wait_for_free_in_flight_slot(s, NULL);
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continue;
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} else if (cnt != 0) {
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delay_ns = mirror_iteration(s);
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--
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1.8.3.1
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