Am 03.02.2014 um 22:51 hat Benoît Canet geschrieben:
> From: Benoît Canet <ben...@irqsave.net>
>
> Example of command line:
> -drive if=virtio,file.driver=quorum,\
> file.children.0.file.filename=1.raw,\
> file.children.0.node-name=1.raw,\
> file.children.0.driver=raw,\
> file.children.1.file.filename=2.raw,\
> file.children.1.node-name=2.raw,\
> file.children.1.driver=raw,\
> file.children.2.file.filename=3.raw,\
> file.children.2.node-name=3.raw,\
> file.children.2.driver=raw,\
> file.vote_threshold=2
>
> file.blkverify=on with file.vote_threshold=2 and two files can be passed to
> emulated blkverify.
>
> Signed-off-by: Benoit Canet <ben...@irqsave.net>
> ---
> block/quorum.c | 171
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> qapi-schema.json | 21 ++++++-
> 2 files changed, 191 insertions(+), 1 deletion(-)
>
> diff --git a/block/quorum.c b/block/quorum.c
> index 1e683f8..d2bea29 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -17,8 +17,12 @@
> #include <gnutls/crypto.h>
> #include "block/block_int.h"
> #include "qapi/qmp/qjson.h"
> +#include "qapi/qmp/types.h"
> +#include "qemu-common.h"
>
> #define HASH_LENGTH 32
> +#define KEY_PREFIX "children."
> +#define KEY_FILENAME_SUFFIX ".file.filename"
>
> /* This union holds a vote hash value */
> typedef union QuorumVoteValue {
> @@ -712,12 +716,179 @@ static bool
> quorum_recurse_is_first_non_filter(BlockDriverState *bs,
> return false;
> }
>
> +static int quorum_valid_threshold(int threshold,
> + int total,
> + Error **errp)
> +{
> +
> + if (threshold < 1) {
> + error_set(errp, QERR_INVALID_PARAMETER_VALUE,
> + "vote-threshold", "value >= 1");
> + return -ERANGE;
> + }
> +
> + if (threshold > total) {
> + error_setg(errp, "threshold may not exceed children count");
> + return -ERANGE;
> + }
> +
> + return 0;
> +}
> +
> +static int quorum_open(BlockDriverState *bs,
> + QDict *options,
> + int flags,
> + Error **errp)
> +{
> + BDRVQuorumState *s = bs->opaque;
> + Error *local_err = NULL;
> + bool *opened;
> + QDict *sub = NULL;
> + QList *list = NULL;
> + const QListEntry *lentry;
> + const QDictEntry *dentry;
> + const char *value;
> + char *next;
> + int i;
> + int ret = 0;
> + unsigned long long threshold = 0;
> +
> + qdict_flatten(options);
> + qdict_extract_subqdict(options, &sub, "children.");
> + qdict_array_split(sub, &list);
> +
> + /* count how many different children are present and validate */
> + s->total = !qlist_size(list) ? qdict_size(sub) : qlist_size(list);
Which case does qdict_size(sub) address?
> + if (s->total < 2) {
> + error_setg(&local_err,
> + "Number of provided children must be greater than 1");
> + ret = -EINVAL;
> + goto exit;
> + }
> +
> + ret = qdict_get_try_int(options, "vote-threshold", -1);
> + /* from QMP */
> + if (ret != -1) {
> + qdict_del(options, "vote-threshold");
> + s->threshold = ret;
> + /* from command line */
> + } else {
> + /* retrieve the threshold option from the command line */
> + value = qdict_get_try_str(options, "vote_threshold");
> + if (!value) {
> + error_setg(&local_err,
> + "vote_threshold must be provided");
> + ret = -EINVAL;
> + goto exit;
> + }
> + qdict_del(options, "vote_threshold");
> +
> + ret = parse_uint(value, &threshold, &next, 10);
> +
> + /* no int found -> scan fail */
> + if (ret < 0) {
> + error_setg(&local_err,
> + "invalid vote_threshold specified");
> + ret = -EINVAL;
> + goto exit;
> + }
> + s->threshold = threshold;
> + }
This part looks seriously wrong. I think you should consider using an
QemuOpts like other drivers do (have a look at qcow2, for example), that
should parse the integer for you.
> + /* and validate it against s->total */
> + ret = quorum_valid_threshold(s->threshold, s->total, &local_err);
> + if (ret < 0) {
> + goto exit;
> + }
> +
> + /* is the driver in blkverify mode */
> + value = qdict_get_try_str(options, "blkverify");
> + if (value && !strcmp(value, "on") &&
> + s->total == 2 && s->threshold == 2) {
> + s->is_blkverify = true;
> + } else if (value && strcmp(value, "off")) {
> + fprintf(stderr, "blkverify mode is set by setting blkverify=on "
> + "and using two files with vote_threshold=2\n");
> + }
> + qdict_del(options, "blkverify");
And the QemuOpts would also know how to parse a boolean.
> +
> + /* allocate the children BlockDriverState array */
> + s->bs = g_new0(BlockDriverState *, s->total);
> + opened = g_new0(bool, s->total);
> +
> + /* Open by file name or options dict (command line or QMP) */
> + if (s->total == qlist_size(list)) {
> + for (i = 0, lentry = qlist_first(list); lentry;
> + lentry = qlist_next(lentry), i++) {
> + ret = bdrv_open(&s->bs[i], NULL, NULL,
> + qobject_to_qdict(lentry->value),
> + flags, NULL, &local_err);
> + if (ret < 0) {
> + goto close_exit;
> + }
> + opened[i] = true;
> + }
> + /* Open by QMP references */
> + } else {
> + for (i = 0, dentry = qdict_first(sub); dentry;
> + dentry = qdict_next(sub, dentry), i++) {
> + ret = bdrv_open(&s->bs[i], NULL,
> +
> qstring_get_str(qobject_to_qstring(dentry->value)),
> + NULL, flags, NULL, &local_err);
> + if (ret < 0) {
> + goto close_exit;
> + }
> + opened[i] = true;
> + }
> + }
What does the reference case look like? (Should work on the command
line, too) I imagine something like this:
-drive if=virtio,file.driver=quorum,\
file.children.0=image0,\
file.children.1=image1,\
file.children.2=image2,\
file.vote_threshold=2
Doesn't qdict_array_split() split this into a list of strings? The whole
thing with directly accessing QDict entries for references confuses me.
> + g_free(opened);
> + goto exit;
> +
> +close_exit:
> + /* cleanup on error */
> + for (i = 0; i < s->total; i++) {
> + if (!opened[i]) {
> + continue;
> + }
> + bdrv_unref(s->bs[i]);
> + }
> + g_free(s->bs);
> + g_free(opened);
> +exit:
> + /* propagate error */
> + if (error_is_set(&local_err)) {
> + error_propagate(errp, local_err);
> + }
> + QDECREF(sub);
> + QDECREF(list);
> + return ret;
> +}
> +
> +static void quorum_close(BlockDriverState *bs)
> +{
> + BDRVQuorumState *s = bs->opaque;
> + int i;
> +
> + for (i = 0; i < s->total; i++) {
> + /* Ensure writes reach stable storage */
> + bdrv_flush(s->bs[i]);
Not necessary, block.c code will flush for us.
> + /* close manually because we'll free s->bs */
> + bdrv_unref(s->bs[i]);
> + }
> +
> + g_free(s->bs);
> +}
Kevin
