qcow2: Add runtime options for cache sizes
Add options for specifying the size of the metadata caches. This can
either be done directly for each cache (if only one is given, the other
will be derived according to a default ratio) or combined for both.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qcow2.c b/block/qcow2.c
index 0f1be2e..f9e045f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -442,6 +442,22 @@
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into an inactive L2 table",
},
+ {
+ .name = QCOW2_OPT_CACHE_SIZE,
+ .type = QEMU_OPT_SIZE,
+ .help = "Maximum combined metadata (L2 tables and refcount blocks) "
+ "cache size",
+ },
+ {
+ .name = QCOW2_OPT_L2_CACHE_SIZE,
+ .type = QEMU_OPT_SIZE,
+ .help = "Maximum L2 table cache size",
+ },
+ {
+ .name = QCOW2_OPT_REFCOUNT_CACHE_SIZE,
+ .type = QEMU_OPT_SIZE,
+ .help = "Maximum refcount block cache size",
+ },
{ /* end of list */ }
},
};
@@ -457,6 +473,61 @@
[QCOW2_OL_INACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L2,
};
+static void read_cache_sizes(QemuOpts *opts, uint64_t *l2_cache_size,
+ uint64_t *refcount_cache_size, Error **errp)
+{
+ uint64_t combined_cache_size;
+ bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
+
+ combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
+ l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
+ refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
+
+ combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0);
+ *l2_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE, 0);
+ *refcount_cache_size = qemu_opt_get_size(opts,
+ QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0);
+
+ if (combined_cache_size_set) {
+ if (l2_cache_size_set && refcount_cache_size_set) {
+ error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE
+ " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set "
+ "the same time");
+ return;
+ } else if (*l2_cache_size > combined_cache_size) {
+ error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed "
+ QCOW2_OPT_CACHE_SIZE);
+ return;
+ } else if (*refcount_cache_size > combined_cache_size) {
+ error_setg(errp, QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not exceed "
+ QCOW2_OPT_CACHE_SIZE);
+ return;
+ }
+
+ if (l2_cache_size_set) {
+ *refcount_cache_size = combined_cache_size - *l2_cache_size;
+ } else if (refcount_cache_size_set) {
+ *l2_cache_size = combined_cache_size - *refcount_cache_size;
+ } else {
+ *refcount_cache_size = combined_cache_size
+ / (DEFAULT_L2_REFCOUNT_SIZE_RATIO + 1);
+ *l2_cache_size = combined_cache_size - *refcount_cache_size;
+ }
+ } else {
+ if (!l2_cache_size_set && !refcount_cache_size_set) {
+ *l2_cache_size = DEFAULT_L2_CACHE_BYTE_SIZE;
+ *refcount_cache_size = *l2_cache_size
+ / DEFAULT_L2_REFCOUNT_SIZE_RATIO;
+ } else if (!l2_cache_size_set) {
+ *l2_cache_size = *refcount_cache_size
+ * DEFAULT_L2_REFCOUNT_SIZE_RATIO;
+ } else if (!refcount_cache_size_set) {
+ *refcount_cache_size = *l2_cache_size
+ / DEFAULT_L2_REFCOUNT_SIZE_RATIO;
+ }
+ }
+}
+
static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
@@ -707,17 +778,43 @@
}
}
- /* alloc L2 table/refcount block cache */
- l2_cache_size = DEFAULT_L2_CACHE_BYTE_SIZE / s->cluster_size;
+ /* get L2 table/refcount block cache size from command line options */
+ opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
+ qemu_opts_absorb_qdict(opts, options, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ read_cache_sizes(opts, &l2_cache_size, &refcount_cache_size, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ ret = -EINVAL;
+ goto fail;
+ }
+
+ l2_cache_size /= s->cluster_size;
if (l2_cache_size < MIN_L2_CACHE_SIZE) {
l2_cache_size = MIN_L2_CACHE_SIZE;
}
+ if (l2_cache_size > INT_MAX) {
+ error_setg(errp, "L2 cache size too big");
+ ret = -EINVAL;
+ goto fail;
+ }
- refcount_cache_size = l2_cache_size / DEFAULT_L2_REFCOUNT_SIZE_RATIO;
+ refcount_cache_size /= s->cluster_size;
if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) {
refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE;
}
+ if (refcount_cache_size > INT_MAX) {
+ error_setg(errp, "Refcount cache size too big");
+ ret = -EINVAL;
+ goto fail;
+ }
+ /* alloc L2 table/refcount block cache */
s->l2_table_cache = qcow2_cache_create(bs, l2_cache_size);
s->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size);
if (s->l2_table_cache == NULL || s->refcount_block_cache == NULL) {
@@ -809,14 +906,6 @@
}
/* Enable lazy_refcounts according to image and command line options */
- opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
- qemu_opts_absorb_qdict(opts, options, &local_err);
- if (local_err) {
- error_propagate(errp, local_err);
- ret = -EINVAL;
- goto fail;
- }
-
s->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
(s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));
