diff options
| author | Kevin Wolf <kwolf@redhat.com> | 2010-01-20 15:03:04 +0100 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2010-01-26 14:59:19 -0600 |
| commit | 09508d13f3874d07bf25f8dd9f5303cbd8139d1b (patch) | |
| tree | 5ff5fa695dc03315235f225a91e74ffdbe3aa451 /block | |
| parent | f2b7c8b37045e0e030ef027cfb6d574558fb732a (diff) | |
qcow2: Improve error handling in update_refcount
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>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow2-refcount.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 6f449c6a70..a84620ffe2 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -278,6 +278,7 @@ 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=%" PRId64 " size=%" PRId64 " addend=%d\n", @@ -292,6 +293,7 @@ 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; @@ -309,10 +311,12 @@ 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 & @@ -326,24 +330,38 @@ 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; } /* addend must be 1 or -1 */ |