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 0f1be2e3846bbb2b4a4a49a4b4bb8ccf06050a96..f9e045ff2be856434d1fcfff55e5ee64b6fdf2be 100644 (file)
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -442,6 +442,22 @@ static QemuOptsList qcow2_runtime_opts = {
             .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 @@ static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
     [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 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
         }
     }
 
-    /* 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 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* 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));
 

diff --git a/block/qcow2.h b/block/qcow2.h
index 671783defec6cd27f747a4d67a14d927d7650af2..6aeb7ea90fd5aaf3b3bb613acee9f51783713a1c 100644 (file)
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -91,6 +91,9 @@
 #define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
+#define QCOW2_OPT_CACHE_SIZE "cache-size"
+#define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
+#define QCOW2_OPT_REFCOUNT_CACHE_SIZE "refcount-cache-size"
 
 typedef struct QCowHeader {
     uint32_t magic;