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Recent change 2c8d6f5c90
actually droped restart when the reason of failing open is missing
device completely - check for ENOENT now as another reason
to start new dmeventd server (when there is no systemd to maintain it).
Use fputs() when printing plain string,
easier then fprintf which needs to parse it.
Also check fd before close is >= 0 -
it is - but coverity fail to see it, so eliminate
this false-positive warning.
Put calls related to fifo opening into a single function.
Fix Time-Of-Check-Time-Of-Use and use fstat()
and fchmod() on already opened fd instead of
checking first path and then risking to open something
different.
If plugin's lvm command execution fails too often (>10 times),
there is no point to torture system more then necessary, just log
and drop monitoring in this case.
Improve event string parser to avoid unneeded alloc+free.
Daemon talk function uses '-' to mark NULL/missing field.
So restore the NULL pointer back on parser.
This should have made old tools like 'dmevent_tool' work again.
As now 'uuid' or 'dso' could become NULL and then be
properly used in _want_registered_device() function.
Since lvm2 always fill these parameters, this change should
have no effect on lvm2.
Older pthread library was missing 'trick'
in pthread_cleanup_pop() which lead to
compilation error:
error: label at end of compound statement
Use explicit ';' to fix it.
Implementing exit when 'dmeventd' is idle.
Default idle timeout set to 1 hour - after this time period
dmeventd will cleanly exit.
On systems with 'systemd' - service is automatically started with
next contact on dmeventd communication socket/fifo.
On other systems - new dmeventd starts again when lvm2 command detects
its missing and monitoring is needed.
Add support to unmonitor device when monitor recognizes there is
nothing to monitor anymore.
TODO: possibly API change with return value could be also used.
Redesign threading code:
- plugin registration runs within its new created thread for
improved parallel usage.
- wait task is created just once and used during whole plugin lifetime.
- event thread is based over 'events' filter being set - when
filter is 0, such thread is 'unused'.
- event loop is simplified.
- timeout thread is never signaling 'processing' thread.
- pending of events filter cnange is properly reported and
running event thread is signalled when possible.
- helgrind is not reporting problems.
Need here to keep control device opened while there is 'any' dso
plugin loaded - otherwise there would a race closing controlfd
inside lvm2 plugin while some other monitoring thread would
tried to execute another WAITEVENT task.
Move all DSO related function in front, so they could be easily
referenced from rest of code.
Add proper error paths with logging and error reporting.
Drop mutex locking when releasing DSO - since DSO is always
allocated and released in main 'event' processing thread.
Respect lvm2_log_fn prototype. The idea of 'reusing' print_log with
plain cast is causing very strange crashes with some older 'gcc' compilers.
So just do it cleanly...
Rework thread creation code to better use resources.
New code will not leak 'timeout' registered thread on error path.
Also if the thread already exist - avoid creation of thread
object and it's later destruction.
If the race is noticed during adding new monitoring thread,
such thread is put on cleanup list and -EEXIST is reported.
As we now use 'unified' logging macro system - we no longer need
to protect from change of logging function pointer - it's set
once at the start of dmeventd and not change anymore
(as lvm2 library no longer interferers here).
There are reports of unexplained ioctl failures when using dmeventd.
An explanation might be that the wrong value of errno is being used.
Change libdevmapper to store an errno set by from dm ioctl() directly
and provide it to the caller through a new dm_task_get_errno() function.
[Replaced f9510548667754d9209b232348ccd2d806c0f1d8]
When responding to DM_EVENT_CMD_GET_REGISTERED_DEVICE no longer
ignore threads that have already been unregistered but which
are still present.
This means the caller can unregister a device and poll dmeventd
to ensure the monitoring thread has gone away before removing
the device. If a device was registered and unregistered in quick
succession and then removed, WAITEVENT could run in parallel with
the REMOVE.
Threads are moved to the _thread_registry_unused list when they
are unregistered.
Switch to allocate buffer from heap, since it might be potentially
bigger when extremaly large set of volumes would be monitored.
In case of allocation failure send ENOMEM message.
Also implicitelly ignore msg->size when msg->data is NULL.
When the last entry in the timeout queue is unregistered,
wakeup sleeping condition, so the thread is deleted earlier.
So the thread resource is release earlier.
Also when monitored with tools like valgrind this eliminites reported
leak.
Individual events are handled through separate threads,
so once we have more then a single thread in this eventwait
sleeping, we got race on the dm_log setting, since
if one event is timeout out on alarm, while another is still waiting,
then dm log has been restored to NULL and the next sigalarm
has been reported as error.
Fix it by introducing counter which is protected via mutex,
and only when the last event is released, logging is restored.
TODO: libdm seems to have some static vars which may audit
for this type of use.
The DM_EVENT_GET_PARAMETERS requests the parameters under which
the running dmeventd is run and the it sends them to caller.
The parameters sent:
- the pid of the running dmeventd
- foreground state
- exec_method (currently either "direct" or "systemd")
The exact message sent back:
pid=<pid> daemon=<no/yes> exec_method=<direct/systemd>
Trying to restart dmeventd as a reload action is causing problems
under systemd environment. The systemd loses track of new dmeventd
this way. See also https://bugzilla.redhat.com/show_bug.cgi?id=1060134
for more info.
We need to call dmeventd -R directly instead of "systemctl reload dm-event.service"
that was used before (the reload is aimed at configuration reload anyway,
not stateful restart of the daemon - we did this before just because
there's no ExecRestart in systemd and there's only ExecStart and
ExecStop with which we'd lose the state).
Also, use ExecStart="dmeventd -f" to run dmeventd in foreground
(and let's rely on systemd to daemonize it) and change the
service type from "forking" to "simple".
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.
Failures in the temporary mirror used when up-converting cause dmeventd
to issue 'lvconvert --repair' on the sub-LV, <lv_name>_mimagetmp_?. The
'lvconvert' command refuses to deal with this sub-LV outright - it
expects to be given the name of the top-level LV. So, just like we do
with mirrored logs, we strip-off the portion of the name that is not
the top-level LV and issue the command on the top-level LV instead.
When creating a timeout thread for snapshots, the thread is not
tracked and thus never joined. This means that the exit status
of the timeout thread is held indefinitely. Saves a bit of
memory to set PTHREAD_CREATE_DETACHED when creating this thread.
I've also added pthread_attr_init|destroy to setup the creation
pthread_attr_t.
Reported-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Start separating the validation from the action in the basic lvresize
code moved to the library.
Remove incorrect use of command line error codes from lvresize library
functions. Move errors.h to tools directory to reinforce this,
exporting public versions of the error codes in lvm2cmd.h for dmeventd
plugins to use.
Instead of calling syslog() from signal event handler,
run all logging code in the main loop.
Also it needs to take the lock and check for list
only when really needed.
Switch to use libdm dm_get_status_snapshot() function for
reading status info.
This fixes bug, where the code was using 32bit integers,
while the snapshot target is able to return 64bit sizes.
However this also means, someone is using >1TB snapshot
cow devices, which is actually very bad idea anyway, since the
perfomance and memory usage in this case is very bad.
Sharing char* with field has a problem in error path,
when we allocate event, but fail to allocate timeout string.
Instead of creating complicated error paths to resolve
it individually stop using unions, and let the resource
to be released in a simple _free_message().
On glibc, those are erroneously (namespace pollution) pulled in via
other headers. this doesn't work with conformant libcs (musl libc in
this case), we simply need to include all needed headers.
Signed-Off-By: John Spencer <maillist-lvm@barfooze.de>
For reseting locale environment into significantly less memory
consuming version 'C' - use LC_ALL instead of LANG since it has
higher priority in locale settings.
Otherwise we may observe whole locale-archive which might be
over 100MB on i.e. Fedora systems locked in memory with
some daemons.
