diff --git a/block.c b/block.c
index d0d9669b66c9348dbd21c160ec759c82cca4f040..1894f1bd62b3bbd26b2d74a85e6d1f78b0364822 100644
--- a/block.c
+++ b/block.c
@@ -29,6 +29,7 @@
#include "qemu/error-report.h"
#include "qemu/module.h"
#include "qapi/qmp/qerror.h"
+#include "qapi/qmp/qbool.h"
#include "qapi/qmp/qjson.h"
#include "sysemu/block-backend.h"
#include "sysemu/sysemu.h"
@@ -706,9 +707,16 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
/* Enable protocol handling, disable format probing for bs->file */
flags |= BDRV_O_PROTOCOL;
+ /* If the cache mode isn't explicitly set, inherit direct and no-flush from
+ * the parent. */
+ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
+ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+
/* Our block drivers take care to send flushes and respect unmap policy,
- * so we can enable both unconditionally on lower layers. */
- flags |= BDRV_O_CACHE_WB | BDRV_O_UNMAP;
+ * so we can default to enable both on lower layers regardless of the
+ * corresponding parent options. */
+ qdict_set_default_str(child_options, BDRV_OPT_CACHE_WB, "on");
+ flags |= BDRV_O_UNMAP;
/* Clear flags that only apply to the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
@@ -747,6 +755,11 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
{
int flags = parent_flags;
+ /* The cache mode is inherited unmodified for backing files */
+ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_WB);
+ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
+ qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+
/* backing files always opened read-only */
flags &= ~(BDRV_O_RDWR | BDRV_O_COPY_ON_READ);
@@ -780,6 +793,42 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags)
return open_flags;
}
+static void update_flags_from_options(int *flags, QemuOpts *opts)
+{
+ *flags &= ~BDRV_O_CACHE_MASK;
+
+ assert(qemu_opt_find(opts, BDRV_OPT_CACHE_WB));
+ if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_WB, false)) {
+ *flags |= BDRV_O_CACHE_WB;
+ }
+
+ assert(qemu_opt_find(opts, BDRV_OPT_CACHE_NO_FLUSH));
+ if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
+ *flags |= BDRV_O_NO_FLUSH;
+ }
+
+ assert(qemu_opt_find(opts, BDRV_OPT_CACHE_DIRECT));
+ if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_DIRECT, false)) {
+ *flags |= BDRV_O_NOCACHE;
+ }
+}
+
+static void update_options_from_flags(QDict *options, int flags)
+{
+ if (!qdict_haskey(options, BDRV_OPT_CACHE_WB)) {
+ qdict_put(options, BDRV_OPT_CACHE_WB,
+ qbool_from_bool(flags & BDRV_O_CACHE_WB));
+ }
+ if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
+ qdict_put(options, BDRV_OPT_CACHE_DIRECT,
+ qbool_from_bool(flags & BDRV_O_NOCACHE));
+ }
+ if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
+ qdict_put(options, BDRV_OPT_CACHE_NO_FLUSH,
+ qbool_from_bool(flags & BDRV_O_NO_FLUSH));
+ }
+}
+
static void bdrv_assign_node_name(BlockDriverState *bs,
const char *node_name,
Error **errp)
@@ -831,6 +880,21 @@ static QemuOptsList bdrv_runtime_opts = {
.type = QEMU_OPT_STRING,
.help = "Block driver to use for the node",
},
+ {
+ .name = BDRV_OPT_CACHE_WB,
+ .type = QEMU_OPT_BOOL,
+ .help = "Enable writeback mode",
+ },
+ {
+ .name = BDRV_OPT_CACHE_DIRECT,
+ .type = QEMU_OPT_BOOL,
+ .help = "Bypass software writeback cache on the host",
+ },
+ {
+ .name = BDRV_OPT_CACHE_NO_FLUSH,
+ .type = QEMU_OPT_BOOL,
+ .help = "Ignore flush requests",
+ },
{ /* end of list */ }
},
};
@@ -925,7 +989,9 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
bs->drv = drv;
bs->opaque = g_malloc0(drv->instance_size);
- bs->enable_write_cache = !!(flags & BDRV_O_CACHE_WB);
+ /* Apply cache mode options */
+ update_flags_from_options(&bs->open_flags, opts);
+ bdrv_set_enable_write_cache(bs, bs->open_flags & BDRV_O_CACHE_WB);
/* Open the image, either directly or using a protocol */
if (drv->bdrv_file_open) {
@@ -1075,6 +1141,9 @@ static int bdrv_fill_options(QDict **options, const char *filename,
*flags &= ~BDRV_O_PROTOCOL;
}
+ /* Translate cache options from flags into options */
+ update_options_from_flags(*options, *flags);
+
/* Fetch the file name from the options QDict if necessary */
if (protocol && filename) {
if (!qdict_haskey(*options, "filename")) {
@@ -1747,12 +1816,22 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
/*
* Precedence of options:
* 1. Explicitly passed in options (highest)
- * 2. TODO Set in flags (only for top level)
+ * 2. Set in flags (only for top level)
* 3. Retained from explicitly set options of bs
* 4. Inherited from parent node
* 5. Retained from effective options of bs
*/
+ if (!parent_options) {
+ /*
+ * Any setting represented by flags is always updated. If the
+ * corresponding QDict option is set, it takes precedence. Otherwise
+ * the flag is translated into a QDict option. The old setting of bs is
+ * not considered.
+ */
+ update_options_from_flags(options, flags);
+ }
+
/* Old explicitly set values (don't overwrite by inherited value) */
old_options = qdict_clone_shallow(bs->explicit_options);
bdrv_join_options(bs, options, old_options);
@@ -1923,6 +2002,19 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
goto error;
}
+ update_flags_from_options(&reopen_state->flags, opts);
+
+ /* If a guest device is attached, it owns WCE */
+ if (reopen_state->bs->blk && blk_get_attached_dev(reopen_state->bs->blk)) {
+ bool old_wce = bdrv_enable_write_cache(reopen_state->bs);
+ bool new_wce = (reopen_state->flags & BDRV_O_CACHE_WB);
+ if (old_wce != new_wce) {
+ error_setg(errp, "Cannot change cache.writeback: Device attached");
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+
/* node-name and driver must be unchanged. Put them back into the QDict, so
* that they are checked at the end of this function. */
value = qemu_opt_get(opts, "node-name");
diff --git a/blockdev.c b/blockdev.c
index 2f88004511984d658f481c7045a095c021e34534..64dbfeb15bd57059c816c4ea5f776711c0068e5e 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -387,16 +387,6 @@ static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
}
}
- if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_WB, true)) {
- *bdrv_flags |= BDRV_O_CACHE_WB;
- }
- if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_DIRECT, false)) {
- *bdrv_flags |= BDRV_O_NOCACHE;
- }
- if (qemu_opt_get_bool(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
- *bdrv_flags |= BDRV_O_NO_FLUSH;
- }
-
if ((aio = qemu_opt_get(opts, "aio")) != NULL) {
if (!strcmp(aio, "native")) {
*bdrv_flags |= BDRV_O_NATIVE_AIO;
@@ -569,9 +559,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
}
if (snapshot) {
- /* always use cache=unsafe with snapshot */
- bdrv_flags &= ~BDRV_O_CACHE_MASK;
- bdrv_flags |= (BDRV_O_SNAPSHOT|BDRV_O_CACHE_WB|BDRV_O_NO_FLUSH);
+ bdrv_flags |= BDRV_O_SNAPSHOT;
}
/* init */
@@ -603,6 +591,20 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
file = NULL;
}
+ /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
+ * with other callers) rather than what we want as the real defaults.
+ * Apply the defaults here instead. */
+ qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_WB, "on");
+ qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
+ qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
+
+ if (snapshot) {
+ /* always use cache=unsafe with snapshot */
+ qdict_put(bs_opts, BDRV_OPT_CACHE_WB, qstring_from_str("on"));
+ qdict_put(bs_opts, BDRV_OPT_CACHE_DIRECT, qstring_from_str("off"));
+ qdict_put(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, qstring_from_str("on"));
+ }
+
blk = blk_new_open(qemu_opts_id(opts), file, NULL, bs_opts, bdrv_flags,
errp);
if (!blk) {
@@ -3869,18 +3871,6 @@ QemuOptsList qemu_common_drive_opts = {
.name = "discard",
.type = QEMU_OPT_STRING,
.help = "discard operation (ignore/off, unmap/on)",
- },{
- .name = BDRV_OPT_CACHE_WB,
- .type = QEMU_OPT_BOOL,
- .help = "enables writeback mode for any caches",
- },{
- .name = BDRV_OPT_CACHE_DIRECT,
- .type = QEMU_OPT_BOOL,
- .help = "enables use of O_DIRECT (bypass the host page cache)",
- },{
- .name = BDRV_OPT_CACHE_NO_FLUSH,
- .type = QEMU_OPT_BOOL,
- .help = "ignore any flush requests for the device",
},{
.name = "aio",
.type = QEMU_OPT_STRING,
@@ -3988,18 +3978,6 @@ static QemuOptsList qemu_root_bds_opts = {
.name = "discard",
.type = QEMU_OPT_STRING,
.help = "discard operation (ignore/off, unmap/on)",
- },{
- .name = "cache.writeback",
- .type = QEMU_OPT_BOOL,
- .help = "enables writeback mode for any caches",
- },{
- .name = "cache.direct",
- .type = QEMU_OPT_BOOL,
- .help = "enables use of O_DIRECT (bypass the host page cache)",
- },{
- .name = "cache.no-flush",
- .type = QEMU_OPT_BOOL,
- .help = "ignore any flush requests for the device",
},{
.name = "aio",
.type = QEMU_OPT_STRING,