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authorKevin Wolf <kwolf@redhat.com>2009-05-26 14:36:03 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2009-05-27 09:45:20 -0500
commita980c98cf1acb3e813428d4f783a8ebd153ef036 (patch)
tree92e2b4bf3e581fa1c2b1cbe5eeb9d860f9ddd60b /block
parent44ff42de1c2df7255108d88e98c2bfe6e7bdbf88 (diff)
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qcow2: Update multiple refcounts at once
Don't write each single changed refcount block entry to the disk after it is written, but update all entries of the block and write all of them at once. 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.c40
1 files changed, 36 insertions, 4 deletions
diff --git a/block/qcow2.c b/block/qcow2.c
index ba946e6..619b923 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2578,6 +2578,9 @@ static int update_refcount(BlockDriverState *bs,
{
BDRVQcowState *s = bs->opaque;
int64_t start, last, cluster_offset;
+ int64_t refcount_block_offset = 0;
+ int64_t table_index = -1, old_table_index;
+ int first_index = -1, last_index = -1;
#ifdef DEBUG_ALLOC2
printf("update_refcount: offset=%lld size=%lld addend=%d\n",
@@ -2590,10 +2593,25 @@ static int update_refcount(BlockDriverState *bs,
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size)
{
- int64_t refcount_block_offset;
int block_index, refcount;
int64_t cluster_index = cluster_offset >> s->cluster_bits;
+ /* Only write refcount block to disk when we are done with it */
+ old_table_index = table_index;
+ table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
+ if ((old_table_index >= 0) && (table_index != old_table_index)) {
+ size_t size = (last_index - first_index + 1) << REFCOUNT_SHIFT;
+ if (bdrv_pwrite(s->hd,
+ refcount_block_offset + (first_index << REFCOUNT_SHIFT),
+ &s->refcount_block_cache[first_index], size) != size)
+ {
+ return -EIO;
+ }
+
+ first_index = -1;
+ last_index = -1;
+ }
+
/* Load the refcount block and allocate it if needed */
refcount_block_offset = alloc_refcount_block(bs, cluster_index);
if (refcount_block_offset < 0) {
@@ -2603,6 +2621,13 @@ static int update_refcount(BlockDriverState *bs,
/* we can update the count and save it */
block_index = cluster_index &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
+ if (first_index == -1 || block_index < first_index) {
+ first_index = block_index;
+ }
+ if (block_index > last_index) {
+ last_index = block_index;
+ }
+
refcount = be16_to_cpu(s->refcount_block_cache[block_index]);
refcount += addend;
if (refcount < 0 || refcount > 0xffff)
@@ -2611,12 +2636,19 @@ static int update_refcount(BlockDriverState *bs,
s->free_cluster_index = cluster_index;
}
s->refcount_block_cache[block_index] = cpu_to_be16(refcount);
+ }
+
+ /* Write last changed block to disk */
+ if (refcount_block_offset != 0) {
+ size_t size = (last_index - first_index + 1) << REFCOUNT_SHIFT;
if (bdrv_pwrite(s->hd,
- refcount_block_offset + (block_index << REFCOUNT_SHIFT),
- &s->refcount_block_cache[block_index], 2) != 2)
+ refcount_block_offset + (first_index << REFCOUNT_SHIFT),
+ &s->refcount_block_cache[first_index], size) != size)
+ {
return -EIO;
-
+ }
}
+
return 0;
}