[Qemu-devel] [PATCH 3/4] qcow2: Add overlap-check.template option

[Max Reitz <mreitz@redhat.com>]

Being able to set the overlap-check option to a string and then refine
it via the overlap-check.* options is a nice idea for the command line
but does not work so well for non-flattened dicts. In that case, one can
only specify either but not both, so add a field to overlap-check.*
which does the same as directly specifying overlap-check but can be used
in conjunction with the other fields in non-flattened dicts.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2.c | 24 ++++++++++++++++++++++--
 block/qcow2.h |  1 +
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index c64d611..c6099b5 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -403,6 +403,12 @@ static QemuOptsList qcow2_runtime_opts = {
                     "templates (none, constant, cached, all)",
         },
         {
+            .name = QCOW2_OPT_OVERLAP_TEMPLATE,
+            .type = QEMU_OPT_STRING,
+            .help = "Selects which overlap checks to perform from a range of "
+                    "templates (none, constant, cached, all)",
+        },
+        {
             .name = QCOW2_OPT_OVERLAP_MAIN_HEADER,
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into the main qcow2 header",
@@ -539,7 +545,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     Error *local_err = NULL;
     uint64_t ext_end;
     uint64_t l1_vm_state_index;
-    const char *opt_overlap_check;
+    const char *opt_overlap_check, *opt_overlap_check_template;
     int overlap_check_template = 0;
     uint64_t l2_cache_size, refcount_cache_size;
 
@@ -919,7 +925,21 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     s->discard_passthrough[QCOW2_DISCARD_OTHER] =
         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);
 
-    opt_overlap_check = qemu_opt_get(opts, "overlap-check") ?: "cached";
+    opt_overlap_check = qemu_opt_get(opts, QCOW2_OPT_OVERLAP);
+    opt_overlap_check_template = qemu_opt_get(opts, QCOW2_OPT_OVERLAP_TEMPLATE);
+    if (opt_overlap_check_template && opt_overlap_check &&
+        strcmp(opt_overlap_check_template, opt_overlap_check))
+    {
+        error_setg(errp, "Conflicting values for qcow2 options '"
+                   QCOW2_OPT_OVERLAP "' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
+                   "' ('%s')", opt_overlap_check, opt_overlap_check_template);
+        ret = -EINVAL;
+        goto fail;
+    }
+    if (!opt_overlap_check) {
+        opt_overlap_check = opt_overlap_check_template ?: "cached";
+    }
+
     if (!strcmp(opt_overlap_check, "none")) {
         overlap_check_template = 0;
     } else if (!strcmp(opt_overlap_check, "constant")) {
diff --git a/block/qcow2.h b/block/qcow2.h
index 6aeb7ea..7806ba1 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -83,6 +83,7 @@
 #define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
 #define QCOW2_OPT_DISCARD_OTHER "pass-discard-other"
 #define QCOW2_OPT_OVERLAP "overlap-check"
+#define QCOW2_OPT_OVERLAP_TEMPLATE "overlap-check.template"
 #define QCOW2_OPT_OVERLAP_MAIN_HEADER "overlap-check.main-header"
 #define QCOW2_OPT_OVERLAP_ACTIVE_L1 "overlap-check.active-l1"
 #define QCOW2_OPT_OVERLAP_ACTIVE_L2 "overlap-check.active-l2"
-- 
2.0.4