Blame SOURCES/kvm-nbd-server-add-nbd_meta_empty_or_pattern-helper.patch

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From de65ad93b1b0a38c8a3f26eb1bc4090eb19db00f Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Wed, 18 Jul 2018 22:55:02 +0200
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Subject: [PATCH 244/268] nbd/server: add nbd_meta_empty_or_pattern helper
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20180718225511.14878-27-jsnow@redhat.com>
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Patchwork-id: 81398
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 26/35] nbd/server: add nbd_meta_empty_or_pattern helper
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Bugzilla: 1207657
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Add nbd_meta_pattern() and nbd_meta_empty_or_pattern() helpers for
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metadata query parsing. nbd_meta_pattern() will be reused for the
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"qemu" namespace in following patches.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Message-Id: <20180609151758.17343-4-vsementsov@virtuozzo.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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[eblake: comment tweaks]
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Signed-off-by: Eric Blake <eblake@redhat.com>
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(cherry picked from commit b0769d8f8df0b51881f1f15c9e29722cf6191a43)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 nbd/server.c | 89 ++++++++++++++++++++++++++++++++++++++++++------------------
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 1 file changed, 62 insertions(+), 27 deletions(-)
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diff --git a/nbd/server.c b/nbd/server.c
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index 26cc41a..9171cd4 100644
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--- a/nbd/server.c
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+++ b/nbd/server.c
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@@ -733,53 +733,87 @@ static int nbd_negotiate_send_meta_context(NBDClient *client,
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     return qio_channel_writev_all(client->ioc, iov, 2, errp) < 0 ? -EIO : 0;
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 }
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-/* nbd_meta_base_query
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- *
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- * Handle queries to 'base' namespace. For now, only the base:allocation
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- * context is available.  'len' is the amount of text remaining to be read from
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- * the current name, after the 'base:' portion has been stripped.
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+/* Read strlen(@pattern) bytes, and set @match to true if they match @pattern.
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+ * @match is never set to false.
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  *
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  * Return -errno on I/O error, 0 if option was completely handled by
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  * sending a reply about inconsistent lengths, or 1 on success.
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  *
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- * Note: return code = 1 doesn't mean that we've parsed the "base:allocation"
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- * namespace. It only means that there are no errors.
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+ * Note: return code = 1 doesn't mean that we've read exactly @pattern.
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+ * It only means that there are no errors.
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  */
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-static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,
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-                               uint32_t len, Error **errp)
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+static int nbd_meta_pattern(NBDClient *client, const char *pattern, bool *match,
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+                            Error **errp)
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 {
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     int ret;
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-    char query[sizeof("allocation") - 1];
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-    size_t alen = strlen("allocation");
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-
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-    if (len == 0) {
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-        if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
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-            meta->base_allocation = true;
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-        }
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-        trace_nbd_negotiate_meta_query_parse("base:");
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-        return 1;
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-    }
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+    char *query;
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+    size_t len = strlen(pattern);
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-    if (len != alen) {
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-        trace_nbd_negotiate_meta_query_skip("not base:allocation");
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-        return nbd_opt_skip(client, len, errp);
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-    }
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+    assert(len);
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+    query = g_malloc(len);
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     ret = nbd_opt_read(client, query, len, errp);
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     if (ret <= 0) {
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+        g_free(query);
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         return ret;
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     }
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-    if (strncmp(query, "allocation", alen) == 0) {
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-        trace_nbd_negotiate_meta_query_parse("base:allocation");
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-        meta->base_allocation = true;
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+    if (strncmp(query, pattern, len) == 0) {
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+        trace_nbd_negotiate_meta_query_parse(pattern);
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+        *match = true;
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     } else {
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-        trace_nbd_negotiate_meta_query_skip("not base:allocation");
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+        trace_nbd_negotiate_meta_query_skip("pattern not matched");
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     }
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+    g_free(query);
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     return 1;
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 }
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+/*
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+ * Read @len bytes, and set @match to true if they match @pattern, or if @len
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+ * is 0 and the client is performing _LIST_. @match is never set to false.
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+ *
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+ * Return -errno on I/O error, 0 if option was completely handled by
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+ * sending a reply about inconsistent lengths, or 1 on success.
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+ *
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+ * Note: return code = 1 doesn't mean that we've read exactly @pattern.
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+ * It only means that there are no errors.
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+ */
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+static int nbd_meta_empty_or_pattern(NBDClient *client, const char *pattern,
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+                                     uint32_t len, bool *match, Error **errp)
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+{
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+    if (len == 0) {
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+        if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
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+            *match = true;
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+        }
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+        trace_nbd_negotiate_meta_query_parse("empty");
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+        return 1;
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+    }
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+
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+    if (len != strlen(pattern)) {
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+        trace_nbd_negotiate_meta_query_skip("different lengths");
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+        return nbd_opt_skip(client, len, errp);
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+    }
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+
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+    return nbd_meta_pattern(client, pattern, match, errp);
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+}
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+
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+/* nbd_meta_base_query
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+ *
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+ * Handle queries to 'base' namespace. For now, only the base:allocation
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+ * context is available.  'len' is the amount of text remaining to be read from
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+ * the current name, after the 'base:' portion has been stripped.
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+ *
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+ * Return -errno on I/O error, 0 if option was completely handled by
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+ * sending a reply about inconsistent lengths, or 1 on success.
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+ */
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+static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,
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+                               uint32_t len, Error **errp)
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+{
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+    return nbd_meta_empty_or_pattern(client, "allocation", len,
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+                                     &meta->base_allocation, errp);
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+}
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+
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 /* nbd_negotiate_meta_query
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  *
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  * Parse namespace name and call corresponding function to parse body of the
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@@ -823,6 +857,7 @@ static int nbd_negotiate_meta_query(NBDClient *client,
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         return nbd_opt_skip(client, len, errp);
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     }
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+    trace_nbd_negotiate_meta_query_parse("base:");
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     return nbd_meta_base_query(client, meta, len, errp);
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 }
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-- 
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1.8.3.1
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