Commit 9991923b authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

qcow2: flush refcount cache correctly in alloc_refcount_block() 



update_refcount() affects the refcount cache, it does not write to disk.
Therefore bdrv_flush(bs->file) does nothing.  We need to flush the
refcount cache in order to write out the refcount updates!

While we're here also add error returns when qcow2_cache_flush() fails.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 74c4510a

block/qcow2-refcount.c

+8 −2
Original line number Diff line number Diff line
@@ -201,7 +201,10 @@ static int alloc_refcount_block(BlockDriverState *bs, 
    *refcount_block = NULL;



    /* We write to the refcount table, so we might depend on L2 tables */

    qcow2_cache_flush(bs, s->l2_table_cache);

    ret = qcow2_cache_flush(bs, s->l2_table_cache);

    if (ret < 0) {

        return ret;

    }



    /* Allocate the refcount block itself and mark it as used */

    int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
@@ -237,7 +240,10 @@ static int alloc_refcount_block(BlockDriverState *bs, 
            goto fail_block;

        }



        bdrv_flush(bs->file);

        ret = qcow2_cache_flush(bs, s->refcount_block_cache);

        if (ret < 0) {

            goto fail_block;

        }



        /* Initialize the new refcount block only after updating its refcount,

         * update_refcount uses the refcount cache itself */