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Since configure.h is a generated header and it's missing traditional
ifdefs preambule - it can be included & parsed multiple times.
Normally compiler is fine when defines have same value and there is
no warning - yet we don't need to parse this several times
and by adding -include directive we can ensure every file
in the package is rightly compile with configure.h as the
first header file.
Since there is very little change there will be any new devel going
to happing with cmirror - avoid eating extra disk space and link
with already installed libdm which implements all use basic
function of dm list
Ensure configure.h is always 1st. included header.
Maybe we could eventually introduce gcc -include option, but for now
this better uses dependency tracking.
Also move _REENTRANT and _GNU_SOURCE into configure.h so it
doesn't need to be present in various source files.
This ensures consistent compilation of headers like stdio.h since
it may produce different declaration.
The device-mapper directory now holds a copy of libdm source. At
the moment this code is identical to libdm. Over time code will
migrate out to appropriate places (see doc/refactoring.txt).
The libdm directory still exists, and contains the source for the
libdevmapper shared library, which we will continue to ship (though
not neccessarily update).
All code using libdm should now use the version in device-mapper.
As we start refactoring the code to break dependencies (see doc/refactoring.txt),
I want us to use full paths in the includes (eg, #include "base/data-struct/list.h").
This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in
metadata/ from base/
I don't like having this in a common header because it means you end
up including too much and causing unneccessary dependencies. eg,
lib/misc/lib.h includes libdevmapper.h, internationalisation, and
logging stuff.
Avoid adding -g more then once for debug builds.
Avoid enabling DEBUG_MEM when we build multithreaded tools.
Link executables with -fPIE -pie and --export-dynamic LDFLAGS
Introduce PROGS_FLAGS to add option to pass flags for external libs.
Link lvm2 internally library only when really used.
Link DAEMON_LIBS with daemons.
Pass VALGRIND_CFLAGS internally
Set shell failure mode on couple places.
With clusters larger than 3 nodes, the 32-byte debug buffer in
cpg_join_callback() is too small to contain all the node IDs, because
32-bit identifiers are generally rendered in 10 decimal digits. No fixed
size is good in all cases, but this is conditionally logged debug info,
so we can simply truncate it. Double the size, nevertheless.
Cmirrord has endian bugs, which cause failure to lvcreate a mirrored lv
on s390.
- data_size is uint32, should not use xlate64 to convert, which will
cause data_size 0 after xlate.
- request_type and data_size still used by local(v5_data_switch),
should convert later. If request_type xlate too early, it will
cause request_type judge error; if data_size xlate too early, it
will cause coredump in case DM_ULOG_CLEAR_REGION.
- when receiving package in clog_request_from_network. vp[0] will always
be little endian. We could use xlate64(vp[0]) == vp[0] to decide if
the local node is little endian or not.
Signed-off-by: Lidong Zhong<lzhong@suse.com> & Liuhua Wang <lwang@suse.com>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
There are two types of CPG communications in a corosync cluster:
messages and state transitions. Cmirrord processes the state
transitions first.
When a cluster mirror issues a POSTSUSPEND, it signals the end of
cluster communication with the rest of the nodes in the cluster.
The POSTSUSPEND marks the last communication of the 'message'
type that will go around the cluster. The node then calls
cpg_leave which causes a final 'state transition' communication to
all of the nodes. Once the out-going node receives its own state
transition notice from the cluster, it finalizes the leave. At this
point, the state of the log is 'INVALID'; but it is possible that
there remains some cluster trafic that was queued up behind the
state transition that still wants to be processed. It is harmless
to attempt to dispatch any remaining messages - they won't be
delivered because the node is no longer in the cluster. However,
there was a warning message that was being printed in this case
that is now removed by this patch. The failure of the dispatch
created a false positive condition that triggered the message.
cmirrord polls for messages on the kernel and cluster interfaces.
Sometimes it is possible for messages to be received on the cluster
interface and be waiting for processing while the node is in the
process of leaving the cluster group. When this happens, the
messages received on the cluster interface are attempted to be
dispatched, but an error is returned because the connection is no
longer valid. It is a harmless situation. So, if we get the
specific error (CS_ERR_BAD_HANDLE) and we know that we have left
the group, then simply don't print the message.
The PIE and RELRO compiler/linker options can be used to produce a code
some techniques applied that makes the code more immune to some attacks:
- PIE (Position Independent Executable). It can make use of the ASLR
(Address Space Layout Randomization) provided by kernel to avoid
static locations for .text regions of executables (this is the 'pie'
compiler and linker option)
- RELRO (Relocation Read-Only). This prevents overwrite attacks of
the GOT (Global Offset Table) and PLT (Procedure Lookup Table)
used for relocations by making it read-only after all relocations
are resolved (these are the 'relro' and 'now' linker options) -
hence all symbols are resolved at the very start so there's no
need for those tables to be writeable later.
These compiler/linker options are now used by default for daemons
if the compiler/linker supports it.
The bug addressed by this patch manifested itself during testing
by showing a mirror that never became 'in-sync' after creation.
The bug is isolated to distributions that do not have support
for openAIS checkpointing (i.e. > RHEL6, > F16).
When a node joins a group that is managing a mirror log, the other
machines in the group send it a checkpoint representing the current
state of the bitmap. More than one machine can send a checkpoint,
but only the initial one should be imported. Once the bitmap state
has been imported from the initial checkpoint, operations (such
as resync, mark, and clear operations) can begin. When subsequent
checkpoints are allowed to be imported, it has the effect of erasing
all the log operations between the initial checkpoint and the ones
that follow.
When cmirrord was updated to handle the absence of openAIS
checkpointing (commit 62e38da133),
the new import_checkpoint() function failed to honor the 'no_read'
parameter. This parameter was designed to avoid reading all but
the initial checkpoint. Honoring this parameter has solved the
issue of corrupting bitmap data with secondary checkpoints.
Looking at the code in cmirrord/local.c, we can see the various different
request types handled in different ways. Some information that is non-changing
does not need to go around the cluster and can be short-circuited. For
example, once the cluster mirror is in-sync, it is pointless to continue
sending that query around the cluster. We can save network bandwidth and reply
directly back to the kernel. When it comes to status information, there are
two types 'TABLE' and 'INFO'. The 'TABLE' information never changes and
belongs to the group of requests that can be safely short-circuited. The
'STATUS' information can change - and will change if a device fails. Thus it
cannot be short-circuited, but this is exactly what was found. The 'STATUS'
information request was being short-circuited and therefore never reporting the
failure condition to anyone other than the "server" that experienced it
directly.
