[Qemu-devel] [PATCH V10 12/13] quorum: Add quorum_open() and quorum_close().

[Benoît Canet]

From: Benoît Canet <address@hidden>

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 <address@hidden>
---
 block/quorum.c   | 308 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json |  21 +++-
 2 files changed, 328 insertions(+), 1 deletion(-)

diff --git a/block/quorum.c b/block/quorum.c
index e7b2090..0c0d630 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 {
@@ -702,12 +706,316 @@ static bool 
quorum_recurse_is_first_non_filter(BlockDriverState *bs,
     return false;
 }
 
+static int quorum_match_key(const char *key,
+                            char **key_prefix)
+{
+    const char *start;
+    char *next;
+    unsigned long long idx;
+    int ret;
+
+    *key_prefix = NULL;
+
+    /* the following code is a translation of the following pseudo code:
+     *       match = key.match('(^children\.(\d+)\.)$suffix)
+     *       if not match:
+     *           return -1;
+     *       key_prefix = match.outer_match()
+     *       idx = match.inner_match()
+     *
+     * note: we also match the .file suffix to avoid futher checkings
+     */
+
+    /* this key is not a child */
+    if (strncmp(key, KEY_PREFIX, strlen(KEY_PREFIX))) {
+        return -1;
+    }
+
+    /* take first char after prefix */
+    start = key + strlen(KEY_PREFIX);
+
+    /* if the string end here -> scan fail */
+    if (start[0] == '\0') {
+        return -1;
+    }
+
+    /* try to retrieve the index */
+    ret = parse_uint(start, &idx, &next, 10);
+
+    /* no int found -> scan fail */
+    if (ret < 0) {
+        return -1;
+    }
+
+    /* we are taking a reference via QMP */
+    if (next - key == strlen(key)) {
+        *key_prefix = g_strdup(key);
+        return idx;
+    }
+
+    /* match the suffix to avoid matching the same idx
+     * multiple times and be required to do more checks later
+     */
+    if (strncmp(next, KEY_FILENAME_SUFFIX, strlen(KEY_FILENAME_SUFFIX))) {
+        return -1;
+    }
+
+    /* do not include '.' */
+    int len = next - key;
+    *key_prefix = g_strndup(key, len);
+
+    return idx;
+}
+
+static QDict *quorum_get_children_idx(const QDict *options)
+{
+    const QDictEntry *ent;
+    QDict *result;
+    char *key_prefix;
+    int idx;
+
+    result = qdict_new();
+
+    for (ent = qdict_first(options); ent; ent = qdict_next(options, ent)) {
+        const char *key = qdict_entry_key(ent);
+        idx = quorum_match_key(key,
+                               &key_prefix);
+
+        /* if the result zero or positive we got a key */
+        if (idx < 0) {
+            continue;
+        }
+
+        qdict_put(result, key_prefix, qint_from_int(idx));
+    }
+
+    return result;
+}
+
+static int quorum_fill_validation_array(bool *array,
+                                        const QDict *dict,
+                                        int total,
+                                        Error **errp)
+{
+    const QDictEntry *ent;
+
+    /* fill the checking array with children indexes */
+    for (ent = qdict_first(dict); ent; ent = qdict_next(dict, ent)) {
+        const char *key = qdict_entry_key(ent);
+        int idx = qdict_get_int(dict, key);
+
+        if (idx < 0 || idx >= total) {
+            error_setg(errp,
+                "Children index must be between 0 and children count -1");
+            return -ERANGE;
+        }
+
+        array[idx] = true;
+    }
+
+    return 0;
+}
+
+static int quorum_valid_indexes(const bool *array, int total, Error **errp)
+{
+    int i;
+
+    for (i = 0; i < total; i++) {
+        if (array[i] == true) {
+            continue;
+        }
+
+        error_setg(errp,
+            "All child indexes between 0 and children count -1  must be "
+            " used");
+        return -ERANGE;
+    }
+
+    return 0;
+}
+
+static int quorum_valid_children_indexes(const QDict *dict,
+                                         int total,
+                                         Error **errp)
+{
+    bool *array;
+    int ret = 0;;
+
+    /* allocate indexes checking array and put false in it */
+    array = g_new0(bool, total);
+
+    ret = quorum_fill_validation_array(array, dict, total, errp);
+    if (ret < 0) {
+        goto free_exit;
+    }
+
+    ret = quorum_valid_indexes(array, total, errp);
+free_exit:
+    g_free(array);
+    return ret;
+}
+
+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 <= children count must be true");
+        return -ERANGE;
+    }
+
+    return 0;
+}
+
+static int quorum_open(BlockDriverState *bs,
+                       QDict *options,
+                       int flags,
+                       Error **errp)
+{
+    BDRVQuorumState *s = bs->opaque;
+    Error *local_err = NULL;
+    const QDictEntry *ent;
+    QDict *idx_dict;
+    bool *opened;
+    const char *value;
+    char *next;
+    int i;
+    int ret = 0;
+
+    /* get a dict of children indexes for validation */
+    idx_dict = quorum_get_children_idx(options);
+
+    /* count how many different children indexes are present and validate */
+    s->total = qdict_size(idx_dict);
+    if (s->total < 2) {
+        error_setg(&local_err,
+                   "Number of provided children must be greater than 1");
+        ret = -EINVAL;
+        goto exit;
+    }
+
+    /* validate that the set of index is coherent */
+    ret = quorum_valid_children_indexes(idx_dict, s->total, &local_err);
+    if (ret < 0) {
+        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, (unsigned long long *) &s->threshold, &next, 
10);
+
+        /* no int found -> scan fail */
+        if (ret < 0) {
+            error_setg(&local_err,
+                       "invalid voter_threshold specified");
+            ret = -EINVAL;
+            goto exit;
+        }
+    }
+
+    /* and validate it againts 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;
+    }
+    qdict_del(options, "blkverify");
+
+    /* allocate the children BlockDriverState array */
+    s->bs = g_new0(BlockDriverState *, s->total);
+    opened = g_new0(bool, s->total);
+
+    /* open children bs */
+    for (ent = qdict_first(idx_dict);
+         ent; ent = qdict_next(idx_dict, ent)) {
+        const char *key = qdict_entry_key(ent);
+        int idx = qdict_get_int(idx_dict, key);
+        ret = bdrv_open_image(&s->bs[idx],
+                              NULL,
+                              options,
+                              key,
+                              flags,
+                              false,
+                              &local_err);
+        if (ret < 0) {
+            goto close_exit;
+        }
+        opened[idx] = true;
+    }
+
+    g_free(opened);
+    goto exit;
+
+close_exit:
+    /* cleanup on error */
+    for (i = 0; i < s->total; i++) {
+        if (!opened[i]) {
+            continue;
+        }
+        bdrv_close(s->bs[i]);
+    }
+    g_free(s->bs);
+    g_free(opened);
+exit:
+    /* propagate error */
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
+    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]);
+        /* close manually because we'll free s->bs */
+        bdrv_close(s->bs[i]);
+    }
+
+    g_free(s->bs);
+}
+
 static BlockDriver bdrv_quorum = {
     .format_name        = "quorum",
     .protocol_name      = "quorum",
 
     .instance_size      = sizeof(BDRVQuorumState),
 
+    .bdrv_file_open     = quorum_open,
+    .bdrv_close         = quorum_close,
+
     .bdrv_co_flush_to_disk = quorum_co_flush,
 
     .bdrv_getlength     = quorum_getlength,
diff --git a/qapi-schema.json b/qapi-schema.json
index 05ced9d..903a3a0 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4352,6 +4352,24 @@
             'raw': 'BlockdevRef' } }
 
 ##
+# @BlockdevOptionsQuorum
+#
+# Driver specific block device options for Quorum
+#
+# @blkverify:      #optional true if the driver must print content mismatch
+#
+# @children:       the children block device to use
+#
+# @vote_threshold: the vote limit under which a read will fail
+#
+# Since: 2.0
+##
+{ 'type': 'BlockdevOptionsQuorum',
+  'data': { '*blkverify': 'bool',
+            'children': [ 'BlockdevRef' ],
+            'vote-threshold': 'int' } }
+
+##
 # @BlockdevOptions
 #
 # Options for creating a block device.
@@ -4389,7 +4407,8 @@
       'vdi':        'BlockdevOptionsGenericFormat',
       'vhdx':       'BlockdevOptionsGenericFormat',
       'vmdk':       'BlockdevOptionsGenericCOWFormat',
-      'vpc':        'BlockdevOptionsGenericFormat'
+      'vpc':        'BlockdevOptionsGenericFormat',
+      'quorum':     'BlockdevOptionsQuorum'
   } }
 
 ##
-- 
1.8.3.2