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[PATCH v3 01/25] tools/xenstore: explicitly specify create or modify for tdb_store()



Instead of using TDB_REPLACE for either creating or modifying a TDB
entry, use either TDB_INSERT or TDB_MODIFY when calling tdb_store().

At higher function levels use the abstract mode values NODE_CREATE
and NODE_MODIFY.

This is for preparing to get rid of TDB, even if it is beneficial
while using TDB, too.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- use an enum for the new "flag" parameter of do_tdb_write()
  (Julien Grall)
- add comment to read_state_node() (Julien Grall)
V3:
- use enum in finalize_transaction() and reduce the scope of it
  (Julien Grall)
---
 tools/xenstore/xenstored_core.c        | 32 +++++++++++++++-----------
 tools/xenstore/xenstored_core.h        | 10 ++++++--
 tools/xenstore/xenstored_domain.c      |  2 +-
 tools/xenstore/xenstored_transaction.c |  9 ++++++--
 4 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 9f1328a31f..b7fdf16718 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -601,7 +601,8 @@ static unsigned int get_acc_domid(struct connection *conn, 
TDB_DATA *key,
 }
 
 int do_tdb_write(struct connection *conn, TDB_DATA *key, TDB_DATA *data,
-                struct node_account_data *acc, bool no_quota_check)
+                struct node_account_data *acc, enum write_node_mode mode,
+                bool no_quota_check)
 {
        struct xs_tdb_record_hdr *hdr = (void *)data->dptr;
        struct node_account_data old_acc = {};
@@ -635,7 +636,8 @@ int do_tdb_write(struct connection *conn, TDB_DATA *key, 
TDB_DATA *data,
        }
 
        /* TDB should set errno, but doesn't even set ecode AFAICT. */
-       if (tdb_store(tdb_ctx, *key, *data, TDB_REPLACE) != 0) {
+       if (tdb_store(tdb_ctx, *key, *data,
+                     (mode == NODE_CREATE) ? TDB_INSERT : TDB_MODIFY) != 0) {
                domain_memory_add_nochk(conn, new_domid,
                                        -data->dsize - key->dsize);
                /* Error path, so no quota check. */
@@ -774,7 +776,7 @@ static bool read_node_can_propagate_errno(void)
 }
 
 int write_node_raw(struct connection *conn, TDB_DATA *key, struct node *node,
-                  bool no_quota_check)
+                  enum write_node_mode mode, bool no_quota_check)
 {
        TDB_DATA data;
        void *p;
@@ -812,7 +814,7 @@ int write_node_raw(struct connection *conn, TDB_DATA *key, 
struct node *node,
        p += node->datalen;
        memcpy(p, node->children, node->childlen);
 
-       if (do_tdb_write(conn, key, &data, &node->acc, no_quota_check))
+       if (do_tdb_write(conn, key, &data, &node->acc, mode, no_quota_check))
                return EIO;
 
        return 0;
@@ -823,14 +825,14 @@ int write_node_raw(struct connection *conn, TDB_DATA 
*key, struct node *node,
  * node->key. This can later be used if the change needs to be reverted.
  */
 static int write_node(struct connection *conn, struct node *node,
-                     bool no_quota_check)
+                     enum write_node_mode mode, bool no_quota_check)
 {
        int ret;
 
        if (access_node(conn, node, NODE_ACCESS_WRITE, &node->key))
                return errno;
 
-       ret = write_node_raw(conn, &node->key, node, no_quota_check);
+       ret = write_node_raw(conn, &node->key, node, mode, no_quota_check);
        if (ret && conn && conn->transaction) {
                /*
                 * Reverting access_node() is hard, so just fail the
@@ -1500,7 +1502,8 @@ static struct node *create_node(struct connection *conn, 
const void *ctx,
                        goto err;
                }
 
-               ret = write_node(conn, i, false);
+               ret = write_node(conn, i, i->parent ? NODE_CREATE : NODE_MODIFY,
+                                false);
                if (ret)
                        goto err;
 
@@ -1564,7 +1567,7 @@ static int do_write(const void *ctx, struct connection 
*conn,
        } else {
                node->data = in->buffer + offset;
                node->datalen = datalen;
-               if (write_node(conn, node, false))
+               if (write_node(conn, node, NODE_MODIFY, false))
                        return errno;
        }
 
@@ -1614,7 +1617,7 @@ static int remove_child_entry(struct connection *conn, 
struct node *node,
        memdel(node->children, offset, childlen + 1, node->childlen);
        node->childlen -= childlen + 1;
 
-       return write_node(conn, node, true);
+       return write_node(conn, node, NODE_MODIFY, true);
 }
 
 static int delete_child(struct connection *conn,
@@ -1812,7 +1815,7 @@ static int do_set_perms(const void *ctx, struct 
connection *conn,
        if (domain_nbentry_inc(conn, get_node_owner(node)))
                return ENOMEM;
 
-       if (write_node(conn, node, false))
+       if (write_node(conn, node, NODE_MODIFY, false))
                return errno;
 
        fire_watches(conn, ctx, name, node, false, &old_perms);
@@ -2326,7 +2329,7 @@ static void manual_node(const char *name, const char 
*child)
        if (child)
                node->childlen = strlen(child) + 1;
 
-       if (write_node(NULL, node, false))
+       if (write_node(NULL, node, NODE_CREATE, false))
                barf_perror("Could not create initial node %s", name);
        talloc_free(node);
 }
@@ -3474,12 +3477,15 @@ void read_state_node(const void *ctx, const void *state)
                        barf("allocation error restoring node");
 
                set_tdb_key(parentname, &key);
-               if (write_node_raw(NULL, &key, parent, true))
+               if (write_node_raw(NULL, &key, parent, NODE_MODIFY, true))
                        barf("write parent error restoring node");
        }
 
        set_tdb_key(name, &key);
-       if (write_node_raw(NULL, &key, node, true))
+
+       /* The "/" node is already existing, so it can only be modified here. */
+       if (write_node_raw(NULL, &key, node,
+                          strcmp(name, "/") ? NODE_CREATE : NODE_MODIFY, true))
                barf("write node error restoring node");
 
        if (domain_nbentry_inc(&conn, get_node_owner(node)))
diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
index 005556de90..19a81adc49 100644
--- a/tools/xenstore/xenstored_core.h
+++ b/tools/xenstore/xenstored_core.h
@@ -238,8 +238,13 @@ static inline unsigned int get_node_owner(const struct 
node *node)
 }
 
 /* Write a node to the tdb data base. */
+enum write_node_mode {
+       NODE_CREATE,
+       NODE_MODIFY
+};
+
 int write_node_raw(struct connection *conn, TDB_DATA *key, struct node *node,
-                  bool no_quota_check);
+                  enum write_node_mode mode, bool no_quota_check);
 
 /* Get a node from the tdb data base. */
 struct node *read_node(struct connection *conn, const void *ctx,
@@ -359,7 +364,8 @@ int remember_string(struct hashtable *hash, const char 
*str);
 
 void set_tdb_key(const char *name, TDB_DATA *key);
 int do_tdb_write(struct connection *conn, TDB_DATA *key, TDB_DATA *data,
-                struct node_account_data *acc, bool no_quota_check);
+                struct node_account_data *acc, enum write_node_mode mode,
+                bool no_quota_check);
 int do_tdb_delete(struct connection *conn, TDB_DATA *key,
                  struct node_account_data *acc);
 
diff --git a/tools/xenstore/xenstored_domain.c 
b/tools/xenstore/xenstored_domain.c
index cc67af5b98..569c3bfbd0 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -523,7 +523,7 @@ static int domain_tree_remove_sub(const void *ctx, struct 
connection *conn,
                node->perms.p[0].id = priv_domid;
                node->acc.memory = 0;
                domain_nbentry_inc(NULL, priv_domid);
-               if (write_node_raw(NULL, &key, node, true)) {
+               if (write_node_raw(NULL, &key, node, NODE_MODIFY, true)) {
                        /* That's unfortunate. We only can try to continue. */
                        syslog(LOG_ERR,
                               "error when moving orphaned node %s to dom0\n",
diff --git a/tools/xenstore/xenstored_transaction.c 
b/tools/xenstore/xenstored_transaction.c
index 334f1609f1..baad9e472d 100644
--- a/tools/xenstore/xenstored_transaction.c
+++ b/tools/xenstore/xenstored_transaction.c
@@ -290,7 +290,8 @@ int access_node(struct connection *conn, struct node *node,
                        i->check_gen = true;
                        if (node->generation != NO_GENERATION) {
                                set_tdb_key(i->trans_name, &local_key);
-                               ret = write_node_raw(conn, &local_key, node, 
true);
+                               ret = write_node_raw(conn, &local_key, node,
+                                                    NODE_CREATE, true);
                                if (ret)
                                        goto err;
                                i->ta_node = true;
@@ -401,12 +402,16 @@ static int finalize_transaction(struct connection *conn,
                        set_tdb_key(i->trans_name, &ta_key);
                        data = tdb_fetch(tdb_ctx, ta_key);
                        if (data.dptr) {
+                               enum write_node_mode mode;
+
                                trace_tdb("read %s size %zu\n", ta_key.dptr,
                                          ta_key.dsize + data.dsize);
                                hdr = (void *)data.dptr;
                                hdr->generation = ++generation;
+                               mode = (i->generation == NO_GENERATION)
+                                      ? NODE_CREATE : NODE_MODIFY;
                                *is_corrupt |= do_tdb_write(conn, &key, &data,
-                                                           NULL, true);
+                                                           NULL, mode, true);
                                talloc_free(data.dptr);
                                if (do_tdb_delete(conn, &ta_key, NULL))
                                        *is_corrupt = true;
-- 
2.35.3




 


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