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[Qemu-devel] [PATCH v5 2/4] qcow2: add qcow2_cache_discard
From: |
Pavel Butsykin |
Subject: |
[Qemu-devel] [PATCH v5 2/4] qcow2: add qcow2_cache_discard |
Date: |
Wed, 12 Jul 2017 14:46:58 +0300 |
Whenever l2/refcount table clusters are discarded from the file we can
automatically drop unnecessary content of the cache tables. This reduces
the chance of eviction useful cache data and eliminates inconsistent data
in the cache with the data in the file.
Signed-off-by: Pavel Butsykin <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
block/qcow2-cache.c | 26 ++++++++++++++++++++++++++
block/qcow2-refcount.c | 14 ++++++++++++++
block/qcow2.h | 3 +++
3 files changed, 43 insertions(+)
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 1d25147392..75746a7f43 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -411,3 +411,29 @@ void qcow2_cache_entry_mark_dirty(BlockDriverState *bs,
Qcow2Cache *c,
assert(c->entries[i].offset != 0);
c->entries[i].dirty = true;
}
+
+void *qcow2_cache_is_table_offset(BlockDriverState *bs, Qcow2Cache *c,
+ uint64_t offset)
+{
+ int i;
+
+ for (i = 0; i < c->size; i++) {
+ if (c->entries[i].offset == offset) {
+ return qcow2_cache_get_table_addr(bs, c, i);
+ }
+ }
+ return NULL;
+}
+
+void qcow2_cache_discard(BlockDriverState *bs, Qcow2Cache *c, void *table)
+{
+ int i = qcow2_cache_get_table_idx(bs, c, table);
+
+ assert(c->entries[i].ref == 0);
+
+ c->entries[i].offset = 0;
+ c->entries[i].lru_counter = 0;
+ c->entries[i].dirty = false;
+
+ qcow2_cache_table_release(bs, c, i, 1);
+}
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index c9b0dcb4f3..8050db4544 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -862,6 +862,20 @@ static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState *bs,
s->set_refcount(refcount_block, block_index, refcount);
if (refcount == 0 && s->discard_passthrough[type]) {
+ void *table;
+
+ table = qcow2_cache_is_table_offset(bs, s->refcount_block_cache,
+ offset);
+ if (table != NULL) {
+ qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+ qcow2_cache_discard(bs, s->refcount_block_cache, table);
+ }
+
+ table = qcow2_cache_is_table_offset(bs, s->l2_table_cache, offset);
+ if (table != NULL) {
+ qcow2_cache_discard(bs, s->l2_table_cache, table);
+ }
+
update_refcount_discard(bs, cluster_offset, s->cluster_size);
}
}
diff --git a/block/qcow2.h b/block/qcow2.h
index 96a8d43c17..52c374e9ed 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -649,6 +649,9 @@ int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c,
uint64_t offset,
int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
void **table);
void qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
+void *qcow2_cache_is_table_offset(BlockDriverState *bs, Qcow2Cache *c,
+ uint64_t offset);
+void qcow2_cache_discard(BlockDriverState *bs, Qcow2Cache *c, void *table);
/* qcow2-bitmap.c functions */
int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
--
2.13.0
- [Qemu-devel] [PATCH v5 0/4] Add shrink image for qcow2, Pavel Butsykin, 2017/07/12
- [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Pavel Butsykin, 2017/07/12
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Kevin Wolf, 2017/07/12
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Max Reitz, 2017/07/12
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Kevin Wolf, 2017/07/13
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Max Reitz, 2017/07/13
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Pavel Butsykin, 2017/07/13
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Kevin Wolf, 2017/07/14
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Pavel Butsykin, 2017/07/13
- Re: [Qemu-devel] [PATCH v5 3/4] qcow2: add shrink image support, Kevin Wolf, 2017/07/14
[Qemu-devel] [PATCH v5 2/4] qcow2: add qcow2_cache_discard,
Pavel Butsykin <=
[Qemu-devel] [PATCH v5 1/4] qemu-img: add --shrink flag for resize, Pavel Butsykin, 2017/07/12
[Qemu-devel] [PATCH v5 4/4] qemu-iotests: add shrinking image test, Pavel Butsykin, 2017/07/12
Re: [Qemu-devel] [PATCH v5 0/4] Add shrink image for qcow2, Max Reitz, 2017/07/12