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Diffstat (limited to 'block/qcow2-cache.c')
-rw-r--r--block/qcow2-cache.c45
1 files changed, 16 insertions, 29 deletions
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 3a318955e6..2035cd8ab2 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -242,51 +242,38 @@ int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c)
return 0;
}
-static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c)
-{
- int i;
- uint64_t min_lru_counter = UINT64_MAX;
- int min_index = -1;
-
-
- for (i = 0; i < c->size; i++) {
- if (c->entries[i].ref) {
- continue;
- }
-
- if (c->entries[i].lru_counter < min_lru_counter) {
- min_index = i;
- min_lru_counter = c->entries[i].lru_counter;
- }
- }
-
- if (min_index == -1) {
- /* This can't happen in current synchronous code, but leave the check
- * here as a reminder for whoever starts using AIO with the cache */
- abort();
- }
- return min_index;
-}
-
static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c,
uint64_t offset, void **table, bool read_from_disk)
{
BDRVQcowState *s = bs->opaque;
int i;
int ret;
+ uint64_t min_lru_counter = UINT64_MAX;
+ int min_lru_index = -1;
trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache,
offset, read_from_disk);
/* Check if the table is already cached */
for (i = 0; i < c->size; i++) {
- if (c->entries[i].offset == offset) {
+ const Qcow2CachedTable *t = &c->entries[i];
+ if (t->offset == offset) {
goto found;
}
+ if (t->ref == 0 && t->lru_counter < min_lru_counter) {
+ min_lru_counter = t->lru_counter;
+ min_lru_index = i;
+ }
+ }
+
+ if (min_lru_index == -1) {
+ /* This can't happen in current synchronous code, but leave the check
+ * here as a reminder for whoever starts using AIO with the cache */
+ abort();
}
- /* If not, write a table back and replace it */
- i = qcow2_cache_find_entry_to_replace(c);
+ /* Cache miss: write a table back and replace it */
+ i = min_lru_index;
trace_qcow2_cache_get_replace_entry(qemu_coroutine_self(),
c == s->l2_table_cache, i);
if (i < 0) {