diff options
| -rw-r--r-- | block/qcow2-refcount.c | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index dd6e293d05..d42c6e6461 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -31,6 +31,26 @@ static int update_refcount(BlockDriverState *bs, int64_t offset, int64_t length, int addend); + +static int cache_refcount_updates = 0; + +static int write_refcount_block(BDRVQcowState *s) +{ + size_t size = s->cluster_size; + + if (s->refcount_block_cache_offset == 0) { + return 0; + } + + if (bdrv_pwrite(s->hd, s->refcount_block_cache_offset, + s->refcount_block_cache, size) != size) + { + return -EIO; + } + + return 0; +} + /*********************************************************/ /* refcount handling */ @@ -68,6 +88,11 @@ static int load_refcount_block(BlockDriverState *bs, { BDRVQcowState *s = bs->opaque; int ret; + + if (cache_refcount_updates) { + write_refcount_block(s); + } + ret = bdrv_pread(s->hd, refcount_block_offset, s->refcount_block_cache, s->cluster_size); if (ret != s->cluster_size) @@ -169,6 +194,7 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) int64_t offset, refcount_block_offset; int ret, refcount_table_index; uint64_t data64; + int cache = cache_refcount_updates; /* Find L1 index and grow refcount table if needed */ refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); @@ -181,6 +207,10 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) /* Load or allocate the refcount block */ refcount_block_offset = s->refcount_table[refcount_table_index]; if (!refcount_block_offset) { + if (cache_refcount_updates) { + write_refcount_block(s); + cache_refcount_updates = 0; + } /* create a new refcount block */ /* Note: we cannot update the refcount now to avoid recursion */ offset = alloc_clusters_noref(bs, s->cluster_size); @@ -199,6 +229,7 @@ static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) refcount_block_offset = offset; s->refcount_block_cache_offset = offset; update_refcount(bs, offset, s->cluster_size, 1); + cache_refcount_updates = cache; } else { if (refcount_block_offset != s->refcount_block_cache_offset) { if (load_refcount_block(bs, refcount_block_offset) < 0) @@ -215,6 +246,10 @@ static int write_refcount_block_entries(BDRVQcowState *s, { size_t size; + if (cache_refcount_updates) { + return 0; + } + first_index &= ~(REFCOUNTS_PER_SECTOR - 1); last_index = (last_index + REFCOUNTS_PER_SECTOR) & ~(REFCOUNTS_PER_SECTOR - 1); @@ -471,6 +506,7 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount; qcow2_l2_cache_reset(bs); + cache_refcount_updates = 1; l2_table = NULL; l1_table = NULL; @@ -563,11 +599,15 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, if (l1_allocated) qemu_free(l1_table); qemu_free(l2_table); + cache_refcount_updates = 0; + write_refcount_block(s); return 0; fail: if (l1_allocated) qemu_free(l1_table); qemu_free(l2_table); + cache_refcount_updates = 0; + write_refcount_block(s); return -EIO; } |