aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorKevin Wolf <kwolf@redhat.com>2011-07-19 13:01:48 +0200
committerKevin Wolf <kwolf@redhat.com>2011-07-19 15:39:22 +0200
commit93913dfd8acbaddc8ef3716cd7b8a2830c99cb19 (patch)
tree4bec586c8b3b30c6ab432fe1237070cfa9a93428
parent4a1d5e1fded54358ddc4d8cbd53388ca7c93499b (diff)
downloadqemu-arm-93913dfd8acbaddc8ef3716cd7b8a2830c99cb19.tar.gz
qcow2: Use Qcow2Cache in writeback mode during loadvm/savevm
In snapshotting there is no guest involved, so we can safely use a writeback mode and do the flushes in the right place (i.e. at the very end). This improves the time that creating/restoring an internal snapshot takes with an image in writethrough mode. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/qcow2-cache.c12
-rw-r--r--block/qcow2-refcount.c38
-rw-r--r--block/qcow2.h2
3 files changed, 41 insertions, 11 deletions
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 382473933c..84088477a4 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -312,3 +312,15 @@ 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;
+}
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index ac95b88fe1..14b2f67f14 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -705,8 +705,15 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
int64_t old_offset, old_l2_offset;
- int i, j, l1_modified, nb_csectors, refcount;
+ int i, j, l1_modified = 0, nb_csectors, refcount;
int ret;
+ bool old_l2_writethrough, old_refcount_writethrough;
+
+ /* Switch caches to writeback mode during update */
+ old_l2_writethrough =
+ qcow2_cache_set_writethrough(bs, s->l2_table_cache, false);
+ old_refcount_writethrough =
+ qcow2_cache_set_writethrough(bs, s->refcount_block_cache, false);
l2_table = NULL;
l1_table = NULL;
@@ -720,7 +727,11 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
l1_allocated = 1;
if (bdrv_pread(bs->file, l1_table_offset,
l1_table, l1_size2) != l1_size2)
+ {
+ ret = -EIO;
goto fail;
+ }
+
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
} else {
@@ -729,7 +740,6 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
l1_allocated = 0;
}
- l1_modified = 0;
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
@@ -773,6 +783,7 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
if (refcount < 0) {
+ ret = -EIO;
goto fail;
}
}
@@ -803,6 +814,7 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
}
if (refcount < 0) {
+ ret = -EIO;
goto fail;
} else if (refcount == 1) {
l2_offset |= QCOW_OFLAG_COPIED;
@@ -813,6 +825,18 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
}
}
+
+ ret = 0;
+fail:
+ if (l2_table) {
+ qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ }
+
+ /* Enable writethrough cache mode again */
+ qcow2_cache_set_writethrough(bs, s->l2_table_cache, old_l2_writethrough);
+ qcow2_cache_set_writethrough(bs, s->refcount_block_cache,
+ old_refcount_writethrough);
+
if (l1_modified) {
for(i = 0; i < l1_size; i++)
cpu_to_be64s(&l1_table[i]);
@@ -824,15 +848,7 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
if (l1_allocated)
qemu_free(l1_table);
- return 0;
- fail:
- if (l2_table) {
- qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
- }
-
- if (l1_allocated)
- qemu_free(l1_table);
- return -EIO;
+ return ret;
}
diff --git a/block/qcow2.h b/block/qcow2.h
index e1ae3e8c2b..6a0a21b694 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -228,6 +228,8 @@ int qcow2_read_snapshots(BlockDriverState *bs);
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
bool writethrough);
int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
+bool qcow2_cache_set_writethrough(BlockDriverState *bs, Qcow2Cache *c,
+ bool enable);
void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);