static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i)
{
BDRVQcowState *s = bs->opaque;
int ret = 0;
if (!c->entries[i].dirty || !c->entries[i].offset) {
return 0;
}
trace_qcow2_cache_entry_flush(qemu_coroutine_self(),
c == s->l2_table_cache, i);
if (c->depends) {
ret = qcow2_cache_flush_dependency(bs, c);
} else if (c->depends_on_flush) {
ret = bdrv_flush(bs->file);
if (ret >= 0) {
c->depends_on_flush = false;
}
}
if (ret < 0) {
return ret;
}
if (c == s->refcount_block_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_REFCOUNT_BLOCK,
c->entries[i].offset, s->cluster_size);
} else if (c == s->l2_table_cache) {
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
c->entries[i].offset, s->cluster_size);
} else {
ret = qcow2_pre_write_overlap_check(bs, 0,
c->entries[i].offset, s->cluster_size);
}
if (ret < 0) {
return ret;
}
if (c == s->refcount_block_cache) {
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART);
} else if (c == s->l2_table_cache) {
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
}
ret = bdrv_pwrite(bs->file, c->entries[i].offset,
qcow2_cache_get_table_addr(bs, c, i), s->cluster_size);
if (ret < 0) {
return ret;
}
c->entries[i].dirty = false;
return 0;
}
static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c,
int i, int num_tables)
{
#if QEMU_MADV_DONTNEED != QEMU_MADV_INVALID
BDRVQcow2State *s = bs->opaque;
void *t = qcow2_cache_get_table_addr(bs, c, i);
int align = getpagesize();
size_t mem_size = (size_t) s->cluster_size * num_tables;
size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t;
size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align);
if (length > 0) {
qemu_madvise((uint8_t *) t + offset, length, QEMU_MADV_DONTNEED);
}
#endif
}
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;
int lookup_index;
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 */
i = lookup_index = (offset / s->cluster_size * 4) % c->size;
do {
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 (++i == c->size) {
i = 0;
}
} while (i != lookup_index);
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();
}
/* 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) {
return i;
}
ret = qcow2_cache_entry_flush(bs, c, i);
if (ret < 0) {
return ret;
}
trace_qcow2_cache_get_read(qemu_coroutine_self(),
c == s->l2_table_cache, i);
c->entries[i].offset = 0;
if (read_from_disk) {
if (c == s->l2_table_cache) {
BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
}
ret = bdrv_pread(bs->file, offset, qcow2_cache_get_table_addr(bs, c, i),
s->cluster_size);
if (ret < 0) {
return ret;
}
}
c->entries[i].offset = offset;
/* And return the right table */
found:
c->entries[i].ref++;
*table = qcow2_cache_get_table_addr(bs, c, i);
trace_qcow2_cache_get_done(qemu_coroutine_self(),
c == s->l2_table_cache, i);
return 0;
}