Right now devicemapper mounts thin device using online discards by default
and passes mount option "discard". Generally people discourage usage of
online discards as they can be a drain on performance. Instead it is
recommended to use fstrim once in a while to reclaim the space.
In case of containers, we recommend to keep data volumes separate. So
there might not be lot of rm, unlink operations going on and there might
not be lot of space being freed by containers. So it might not matter
much if we don't reclaim that free space in pool.
User can still pass mount option explicitly using dm.mountopt=discard to
enable discards if they would like to.
So this is more like setting the containers by default for better performance
instead of better space efficiency in pool. And user can change the behavior
if they don't like default behavior.
Reported-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
This provides an override for forcing the daemon to still attempt
running the devicemapper driver even when udev sync is not supported.
Intended to be a very clear impairment for those choosing to use it. If
udev sync is false, there will still be an error in the daemon logs,
even when the override is in place. The docs have an explicit WARNING.
Including link to the docs for users that encounter this daemon error
during an upgrade.
Signed-off-by: Vincent Batts <vbatts@redhat.com>
Right now we try device removal at the interval of 10ms and keep on trying
till either device is removed or 10 seconds are over. That means if device
is busy, we will try 1000 times in those 10 seconds.
Sounds too high a frequency of deivce removal retrial. All the logs are
filled easily. I think it is a good idea to slow down a bit and retry at
the interval of 100ms instead of 10ms.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
During device removal, we are first waiting for device to close() in a tight
loop for 10 seconds. I am not sure why do we need it. First of all we come
here once the umount() is successful so device should be free. For some reason
of device is temporarily busy, then removeDevice() logic retries device removal
logic in a loop for 10 seconds and that should cover it. Can't see why one
more 10 seoncds loop is required before attempting device removal.
One loop should be able to cover all the temporary device busy conditions and
if condition is not temporary then 10 seconds loop is not going to help anyway.
So instead of two loops of 10 seconds each, I am converting it to a single
loop of 20 seconds. May be 10 second loop is good enough but for now I am
keeping it 20 seconds to avoid any regressions.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Currently in device removal path (device deactivation), we wait
for 10 seconds for devive to actually go away. waitRemove().
In current code this is not required. If dm removal task has completed
and one has done the wait on udev cookie, then device is gone and there
is no need to write another loop to wait for device removal.
This patch removes the waitRemove() which waits for 10 seconds after
device removal. This seems unnecessary.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
devmapper graph driver retries device removal 1000 times in case of failure
and if this fills up console with 1000 messages (when daemon is running in
debug mode). So remove these debug messages.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
There are issues with libdm logging. Right now if docker daemon is run
in debug mode, logging by libdm is too verbose. And if a device can't
be removed, thousands of messages fill the console and one can not see
what's going on.
This patch removes devicemapper.LogInitVerbose() call as that call will
only work if docker was not registering its own log handler with libdm.
For some reason docker registers one with libdm and libdm hands over
all the messages to docker (including debug ones). And now it is up to
devmapper backend to figure out which ones should go to console and
which ones should not.
So by default log only fatal messages from libdm. One can easily modify
the code to change it for debugging purposes.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
when initializing the devmapper driver, attempt to sync udev and device
mapper. If udev sync is not supported, print a warning. Eventually we'll
likely bail here to avoid unpredictable behavior for users.
Signed-off-by: Vincent Batts <vbatts@redhat.com>
Fixes#9960
This adds the output of a "Backing Filesystem:" entry to `docker info`
to overlay, aufs, and devicemapper graphdrivers. The default list
includes a fairly complete list of common filesystem names from
linux/include/uapi/linux/magic.h, but if the backing filesystem is not
recognized, the code will simply show "<unknown>"
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>
There are a couple of drivers that swallow errors that may occur in
their Put() implementation.
This changes the signature of (*Driver).Put for all the drivers implemented.
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
Presenly the "Data file:" shows either the loopback _file_ or the block device.
With this, the "Data file:" will always show the device, and if it is a
loopback, then there will additionally be a "Data loop file:".
(Same for "Metadata file:")
Signed-off-by: Vincent Batts <vbatts@redhat.com>
syscall.Unmount failed sometimes when user interrupted exporting,
for example a Ctrl-C, or pipe to commands which closed the pipe early,
like "docker export <container_name> | file -"; this syscall.Unmount
could sometimes return EBUSY and didn't actually umount the filesystem;
which would cause a following export command fail to mount;
change to lazy Unmount with MNT_DETACH can fix the problem, this is
the same behavior as in Shutdown;
```text
time="2015-01-03T21:27:26Z" level=error msg="Warning: error unmounting device
34a3e77cdbca17ceffd0636aee0415bb412996adb12360bfe2585ce30467fa8e: device or resource busy"
```
```
$ docker export thirsty_ardinghelli | file -
/dev/stdin: POSIX tar archive
time="2015-01-03T21:58:17Z" level=fatal msg="write /dev/stdout: broken pipe"
$ docker export thirsty_ardinghelli
time="2015-01-03T21:54:33Z" level=fatal msg="Error: thirsty_ardinghelli: Error getting container
34a3e77cdbca17ceffd0636aee0415bb412996adb12360bfe2585ce30467fa8e from driver devicemapper:
Error mounting '/dev/mapper/docker-253:0-3148372-34a3e77cdbca17ceffd0636aee0415bb412996adb12360bfe2585ce30467fa8e'
on '/var/lib/docker/devicemapper/mnt/34a3e77cdbca17ceffd0636aee0415bb412996adb12360bfe2585ce30467fa8e': device or resource busy"
```
Signed-off-by: Derek Che <drc@yahoo-inc.com>
Use transaction logic during device deletion and do rollback if transaction
is not complete. Following is the sequence of events.
- Open transaction and save to metafile
- Delete device from pool
- Delete device metadata file from disk
- Close Transaction
If docker crashes without closing transaction then rollback will take
place upon next docker start.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Finally this patch uses the notion of transaction for device or snapshot
device creation.
Following is sequence of event.
- Open a trasaction and save details in a file.
- Create a new device/snapshot device
- If a new device id is used, refresh transaction with new device id details.
- Create device metadata file
- Close transaction.
If docker crashes anywhere in between without closing transaction, then
upon next start, docker will figure out that there was a pending transaction
and it will roll back transaction. That is it will do following.
- Delete Device from pool
- Delete device metadata file
- Remove transaction file to mark no transaction is pending.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Finally, we seem to have all the bits to keep track of all used device
Ids and find a free device Id to use when creating a new device. Start
using it.
Ideally we should completely move away from retry logic when pool returns
-EEXISTS. For now I have retained that logic and I simply output a warning.
When things are stable, we should be able to get rid of it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Open code createDevice() and createSnapDevice() and move all the logic
in the caller.
This is a sheer code reorganization so that all device Id allocation
logic is in one function. That way in case of erros, one can easily
cleanup and mark device Id free again. (Later patches benefit from
it).
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
