From 64a58b0c174552396630862e4556d904d61509b2 Mon Sep 17 00:00:00 2001 From: Kevin Wolf <kwolf@redhat.com> Date: Thu, 21 Jan 2010 14:03:05 -0200 Subject: [PATCH 07/10] qcow2: Improve error handling in update_refcount RH-Author: Kevin Wolf <kwolf@redhat.com> Message-id: <1264082588-10273-8-git-send-email-kwolf@redhat.com> Patchwork-id: 6516 O-Subject: [RHEL-5.5 KVM PATCH 07/10] qcow2: Improve error handling in update_refcount Bugzilla: 537077 RH-Acked-by: Christoph Hellwig <chellwig@redhat.com> RH-Acked-by: Juan Quintela <quintela@redhat.com> RH-Acked-by: Gleb Natapov <gleb@redhat.com> RH-Acked-by: Markus Armbruster <armbru@redhat.com> Bugzilla: 537077 Upstream status: Submitted If update_refcount fails, try to undo any changes made so far to avoid inconsistencies in the image file. Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- qemu/block-qcow2.c | 32 +++++++++++++++++++++++++------- 1 files changed, 25 insertions(+), 7 deletions(-) Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> --- qemu/block-qcow2.c | 32 +++++++++++++++++++++++++------- 1 files changed, 25 insertions(+), 7 deletions(-) diff --git a/qemu/block-qcow2.c b/qemu/block-qcow2.c index e0d60b7..4dc2886 100644 --- a/qemu/block-qcow2.c +++ b/qemu/block-qcow2.c @@ -2788,6 +2788,7 @@ static int update_refcount(BlockDriverState *bs, int64_t refcount_block_offset = 0; int64_t table_index = -1, old_table_index; int first_index = -1, last_index = -1; + int ret; #ifdef DEBUG_ALLOC2 printf("update_refcount: offset=%lld size=%lld addend=%d\n", @@ -2802,6 +2803,7 @@ static int update_refcount(BlockDriverState *bs, { int block_index, refcount; int64_t cluster_index = cluster_offset >> s->cluster_bits; + int64_t new_block; /* Only write refcount block to disk when we are done with it */ old_table_index = table_index; @@ -2819,10 +2821,12 @@ static int update_refcount(BlockDriverState *bs, } /* Load the refcount block and allocate it if needed */ - refcount_block_offset = alloc_refcount_block(bs, cluster_index); - if (refcount_block_offset < 0) { - return refcount_block_offset; + new_block = alloc_refcount_block(bs, cluster_index); + if (new_block < 0) { + ret = new_block; + goto fail; } + refcount_block_offset = new_block; /* we can update the count and save it */ block_index = cluster_index & @@ -2836,24 +2840,38 @@ static int update_refcount(BlockDriverState *bs, refcount = be16_to_cpu(s->refcount_block_cache[block_index]); refcount += addend; - if (refcount < 0 || refcount > 0xffff) - return -EINVAL; + if (refcount < 0 || refcount > 0xffff) { + ret = -EINVAL; + goto fail; + } if (refcount == 0 && cluster_index < s->free_cluster_index) { s->free_cluster_index = cluster_index; } s->refcount_block_cache[block_index] = cpu_to_be16(refcount); } + ret = 0; +fail: + /* Write last changed block to disk */ if (refcount_block_offset != 0) { if (write_refcount_block_entries(s, refcount_block_offset, first_index, last_index) < 0) { - return -EIO; + return ret < 0 ? ret : -EIO; } } - return 0; + /* + * Try do undo any updates if an error is returned (This may succeed in + * some cases like ENOSPC for allocating a new refcount block) + */ + if (ret < 0) { + int dummy; + dummy = update_refcount(bs, offset, cluster_offset - offset, -addend); + } + + return ret; } /* -- 1.6.3.rc4.29.g8146