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blockdev: acquire aio_context for bitmap add/remove 

When bitmaps are persistent, they may incur a disk read or write when bitmaps
are added or removed. For configurations like virtio-dataplane, failing to
acquire this lock will abort QEMU when disk IO occurs.

We used to acquire aio_context as part of the bitmap lookup, so re-introduce
the lock for just the cases that have an IO penalty. Commit 2119882c removed
these locks, and I failed to notice this when we committed fd5ae4cc, so this
has been broken since persistent bitmaps were introduced.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1672010
Reported-By: Aihua Liang <aliang@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190218233154.19303-1-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
John Snow 2019-02-19 17:49:43 -05:00
parent 73ab5d601c
commit 0a6c86d024
1 changed files with 20 additions and 6 deletions
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26
blockdev.c
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@ -2820,6 +2820,7 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
{
BlockDriverState *bs;
BdrvDirtyBitmap *bitmap;
AioContext *aio_context = NULL;
if (!name || name[0] == '\0') {
error_setg(errp, "Bitmap name cannot be empty");
@ -2854,15 +2855,17 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
disabled = false;
}
if (persistent &&
!bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp))
{
return;
if (persistent) {
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
if (!bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp)) {
goto out;
}
}
bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
if (bitmap == NULL) {
return;
goto out;
}
if (disabled) {
@ -2870,6 +2873,10 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
}
bdrv_dirty_bitmap_set_persistance(bitmap, persistent);
out:
if (aio_context) {
aio_context_release(aio_context);
}
}
void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
@ -2878,6 +2885,7 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
BlockDriverState *bs;
BdrvDirtyBitmap *bitmap;
Error *local_err = NULL;
AioContext *aio_context = NULL;
bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
if (!bitmap || !bs) {
@ -2892,14 +2900,20 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
}
if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_remove_persistent_dirty_bitmap(bs, name, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
return;
goto out;
}
}
bdrv_release_dirty_bitmap(bs, bitmap);
out:
if (aio_context) {
aio_context_release(aio_context);
}
}
/**