From a55bd292116344617f738548bec268c46aedd7e1 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 18 Jun 2010 15:22:33 -0300
Subject: [PATCH 15/18] qcow2: Allow alloc_clusters_noref to return errors

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1276874554-9820-16-git-send-email-kwolf@redhat.com>
Patchwork-id: 9990
O-Subject: [RHEL-5.6 KVM PATCH 15/16] qcow2: Allow alloc_clusters_noref to
	return errors
Bugzilla: 605701
RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Christoph Hellwig <chellwig@redhat.com>
RH-Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>

Bugzilla: 605701
Upstream commit: 2eaa8f633854b623050cf000febe989d144927fe

Currently it would consider blocks for which get_refcount fails used. However,
it's unlikely that get_refcount would succeed for the next cluster, so it's not
really helpful. Return an error instead.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qemu/block-qcow2.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/block-qcow2.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/qemu/block-qcow2.c b/qemu/block-qcow2.c
index d835efd..8df2f29 100644
--- a/qemu/block-qcow2.c
+++ b/qemu/block-qcow2.c
@@ -2630,14 +2630,19 @@ static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
 static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
 {
     BDRVQcowState *s = bs->opaque;
-    int i, nb_clusters;
+    int i, nb_clusters, refcount;
 
     nb_clusters = size_to_clusters(s, size);
 retry:
     for(i = 0; i < nb_clusters; i++) {
-        int64_t i = s->free_cluster_index++;
-        if (get_refcount(bs, i) != 0)
+        int64_t next_cluster_index = s->free_cluster_index++;
+        refcount = get_refcount(bs, next_cluster_index);
+
+        if (refcount < 0) {
+            return refcount;
+        } else if (refcount != 0) {
             goto retry;
+        }
     }
 #ifdef DEBUG_ALLOC2
     printf("alloc_clusters: size=%lld -> %lld\n",
@@ -2668,6 +2673,10 @@ static int64_t alloc_clusters(BlockDriverState *bs, int64_t size)
     int ret;
 
     offset = alloc_clusters_noref(bs, size);
+    if (offset < 0) {
+        return offset;
+    }
+
     ret = update_refcount(bs, offset, size, 1);
     if (ret < 0) {
         return ret;
@@ -2817,7 +2826,10 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index)
      */
 
     /* Allocate the refcount block itself and mark it as used */
-    uint64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
+    int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
+    if (new_block < 0) {
+        return new_block;
+    }
 
 #ifdef DEBUG_ALLOC2
     fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
-- 
1.7.0.3