# HG changeset patch
# User Rusty Russell <rusty@xxxxxxxxxxxxxxx>
# Node ID 703e0e8e7efce364f62a79b209af0d48195b6825
# Parent 6d2f8b0a18c4713286a16d22fd2a11d7ab4525b4
Delay delete of transaction file when transaction fails with EAGAIN.
Randomized testing with killing xenstored reveals a flaw: if it dies before
client gets response from xs_transaction_end (ie. transaction commit), we can't
tell if commit failed (EAGAIN) or succeeded. This is the only non-repeatable
operation.
Note that this won't happen on a clean shutdown, but delaying delete allows us
to handle the unexpected death case: the client will reconnect, attach to
transaction again, the second commit attempt will fail.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
diff -r 6d2f8b0a18c4 -r 703e0e8e7efc tools/xenstore/xenstored_core.c
--- a/tools/xenstore/xenstored_core.c Mon Sep 26 04:30:14 2005
+++ b/tools/xenstore/xenstored_core.c Mon Sep 26 10:53:13 2005
@@ -1185,6 +1185,12 @@
if (type != XS_WATCH_ACK)
conn->waiting_for_ack = NULL;
+ /* Now we're sure they know transaction is over. */
+ if (conn->last_transaction) {
+ talloc_free(conn->last_transaction);
+ conn->last_transaction = NULL;
+ }
+
/* Careful: process_message may free connection. We detach
* "in" beforehand and allocate the new buffer to avoid
* touching conn after process_message.
@@ -1282,7 +1288,7 @@
new->fd = -1;
new->id = 0;
new->domain = NULL;
- new->transaction = NULL;
+ new->transaction = new->last_transaction = NULL;
new->write = write;
new->read = read;
new->can_write = true;
diff -r 6d2f8b0a18c4 -r 703e0e8e7efc tools/xenstore/xenstored_core.h
--- a/tools/xenstore/xenstored_core.h Mon Sep 26 04:30:14 2005
+++ b/tools/xenstore/xenstored_core.h Mon Sep 26 10:53:13 2005
@@ -84,8 +84,8 @@
/* If we had a watch fire outgoing when we needed to reply... */
struct buffered_data *waiting_reply;
- /* My transaction, if any. */
- struct transaction *transaction;
+ /* My transaction, if any, and aborted one. */
+ struct transaction *transaction, *last_transaction;
/* The domain I'm associated with, if any. */
struct domain *domain;
diff -r 6d2f8b0a18c4 -r 703e0e8e7efc tools/xenstore/xenstored_transaction.c
--- a/tools/xenstore/xenstored_transaction.c Mon Sep 26 04:30:14 2005
+++ b/tools/xenstore/xenstored_transaction.c Mon Sep 26 10:53:13 2005
@@ -219,6 +219,8 @@
if (streq(arg, "T")) {
/* FIXME: Merge, rather failing on any change. */
if (trans->generation != generation) {
+ /* Keep transaction around: more robust if we die. */
+ conn->last_transaction = talloc_steal(conn, trans);
send_error(conn, EAGAIN);
return;
}
@@ -248,7 +250,7 @@
transdir = talloc_strdup(talloc_autofree_context(), xs_daemon_tdb());
if (strrchr(transdir, '/'))
- *strchr(transdir, '/') = '\0';
+ *strrchr(transdir, '/') = '\0';
else
transdir = talloc_strdup(transdir, ".");
@@ -267,6 +269,7 @@
if (!trans->tdb) {
eprintf("Could not reopen transaction %i: corrupt?",
id);
+ unlink(trans->tdb_name);
talloc_free(trans);
}
}
--
A bad analogy is like a leaky screwdriver -- Richard Braakman
_______________________________________________
Xen-tools mailing list
Xen-tools@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-tools
|
Home