There is a possibility to hit assert qcow2_get_specific_info that
s->qcow_version is undefined. This happens when VM in starting from
suspended state, i.e. it processes incoming migration, and in the same
time 'info block' is called.
The problem is that in the qcow2_invalidate_cache closes and the image
and memsets BDRVQcowState in the middle.
The patch moves processing of qcow2_get_specific_info into coroutine
context and ensures that qcow2_invalidate_cache and qcow2_get_specific_info
can not run simultaneosly.
Signed-off-by: Denis V. Lunev <d...@openvz.org>
CC: Kevin Wolf <kw...@redhat.com>
CC: Paolo Bonzini <pbonz...@redhat.com>
---
block/qcow2.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
block/qcow2.h | 2 ++
2 files changed, 61 insertions(+), 5 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 1789af4..12eda24 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1740,6 +1740,10 @@ static void qcow2_invalidate_cache(BlockDriverState *bs,
Error **errp)
Error *local_err = NULL;
int ret;
+ qemu_co_mutex_lock(&s->lock);
+ s->in_transient_state = true;
+ qemu_co_mutex_unlock(&s->lock);
+
/*
* Backing files are read-only which makes all of their metadata
immutable,
* that means we don't have to worry about reopening them here.
@@ -1753,10 +1757,10 @@ static void qcow2_invalidate_cache(BlockDriverState
*bs, Error **errp)
bdrv_invalidate_cache(bs->file->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
- return;
+ goto done;
}
- memset(s, 0, sizeof(BDRVQcow2State));
+ memset(s, 0, offsetof(BDRVQcow2State, in_transient_state));
options = qdict_clone_shallow(bs->options);
ret = qcow2_open(bs, options, flags, &local_err);
@@ -1765,13 +1769,18 @@ static void qcow2_invalidate_cache(BlockDriverState
*bs, Error **errp)
error_setg(errp, "Could not reopen qcow2 layer: %s",
error_get_pretty(local_err));
error_free(local_err);
- return;
+ goto done;
} else if (ret < 0) {
error_setg_errno(errp, -ret, "Could not reopen qcow2 layer");
- return;
+ goto done;
}
s->cipher = cipher;
+
+done:
+ qemu_co_mutex_lock(&s->lock);
+ s->in_transient_state = false;
+ qemu_co_mutex_unlock(&s->lock);
}
static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
@@ -2778,11 +2787,21 @@ static int qcow2_get_info(BlockDriverState *bs,
BlockDriverInfo *bdi)
return 0;
}
-static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs)
+
+static ImageInfoSpecific *qcow2_co_get_specific_info(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
+ AioContext *ctx = bdrv_get_aio_context(bs);
+
ImageInfoSpecific *spec_info = g_new(ImageInfoSpecific, 1);
+ qemu_co_mutex_lock(&s->lock);
+ while (s->in_transient_state) {
+ qemu_co_mutex_unlock(&s->lock);
+ aio_poll(ctx, true);
+ qemu_co_mutex_lock(&s->lock);
+ }
+
*spec_info = (ImageInfoSpecific){
.type = IMAGE_INFO_SPECIFIC_KIND_QCOW2,
.u.qcow2 = g_new(ImageInfoSpecificQCow2, 1),
@@ -2808,10 +2827,45 @@ static ImageInfoSpecific
*qcow2_get_specific_info(BlockDriverState *bs)
* added without having it covered here */
assert(false);
}
+ qemu_co_mutex_unlock(&s->lock);
return spec_info;
}
+struct InfoCo {
+ BlockDriverState *bs;
+ ImageInfoSpecific *info;
+};
+
+static void qcow2_co_get_specific_info_entry(void *opaque)
+{
+ struct InfoCo *ret = opaque;
+ ret->info = qcow2_co_get_specific_info(ret->bs);
+}
+
+static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs)
+{
+ Coroutine *co;
+ struct InfoCo info_co = {
+ .bs = bs,
+ };
+
+ if (qemu_in_coroutine()) {
+ /* Fast-path if already in coroutine context */
+ qcow2_co_get_specific_info_entry(&info_co);
+ } else {
+ AioContext *aio_context = bdrv_get_aio_context(bs);
+
+ co = qemu_coroutine_create(qcow2_co_get_specific_info_entry);
+ qemu_coroutine_enter(co, &info_co);
+ while (info_co.info == NULL) {
+ aio_poll(aio_context, true);
+ }
+ }
+
+ return info_co.info;
+}
+
#if 0
static void dump_refcounts(BlockDriverState *bs)
{
diff --git a/block/qcow2.h b/block/qcow2.h
index a063a3c..1114528 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -293,6 +293,8 @@ typedef struct BDRVQcow2State {
* override) */
char *image_backing_file;
char *image_backing_format;
+
+ bool in_transient_state;
} BDRVQcow2State;
typedef struct Qcow2COWRegion {
