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qcow2: always operate caches in writeback mode

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Writethrough does not need special-casing anymore in the qcow2 caches.
The block layer adds flushes after every guest-initiated data write,
and these will also flush the qcow2 caches to the OS.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-06-06 00:04:55 +02:00 • committed by Kevin Wolf
parent 7cdd481cdf
commit 6af4e9ead4
4 changed files with 5 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

25
block/qcow2-cache.c
View file

@ -40,11 +40,9 @@ struct Qcow2Cache {
struct Qcow2Cache* depends;
int size;
bool depends_on_flush;
bool writethrough;
};
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
bool writethrough)
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
{
BDRVQcowState *s = bs->opaque;
Qcow2Cache *c;
@ -53,7 +51,6 @@ Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
c = g_malloc0(sizeof(*c));
c->size = num_tables;
c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
c->writethrough = writethrough;
for (i = 0; i < c->size; i++) {
c->entries[i].table = qemu_blockalign(bs, s->cluster_size);
@ -307,12 +304,7 @@ found:
*table = NULL;
assert(c->entries[i].ref >= 0);
if (c->writethrough) {
return qcow2_cache_entry_flush(bs, c, i);
} else {
return 0;
}
return 0;
}
void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table)
@ -329,16 +321,3 @@ void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table)
found:
c->entries[i].dirty = true;
}
bool qcow2_cache_set_writethrough(BlockDriverState *bs, Qcow2Cache *c,
bool enable)
{
bool old = c->writethrough;
if (!old && enable) {
qcow2_cache_flush(bs, c);
}
c->writethrough = enable;
return old;
}