linux-toradex.git/include/linux/drbd_genl.h, branch v4.12

genetlink: statically initialize families

2016-10-27T20:16:09+00:00

Instead of providing macros/inline functions to initialize
the families, make all users initialize them statically and
get rid of the macros.

This reduces the kernel code size by about 1.6k on x86-64
(with allyesconfig).

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller

drbd: when receiving P_TRIM, zero-out partial unaligned chunks

2016-06-14T03:43:05+00:00

We can avoid spurious data divergence caused by partially-ignored
discards on certain backends with discard_zeroes_data=0, if we
translate partial unaligned discard requests into explicit zero-out.

The relevant use case is LVM/DM thin.

If on different nodes, DRBD is backed by devices with differing
discard characteristics, discards may lead to data divergence
(old data or garbage left over on one backend, zeroes due to
unmapped areas on the other backend). Online verify would now
potentially report tons of spurious differences.

While probably harmless for most use cases (fstrim on a file system),
DRBD cannot have that, it would violate our promise to upper layers
that our data instances on the nodes are identical.

To be correct and play safe (make sure data is identical on both copies),
we would have to disable discard support, if our local backend (on a
Primary) does not support "discard_zeroes_data=true".

We'd also have to translate discards to explicit zero-out on the
receiving (typically: Secondary) side, unless the receiving side
supports "discard_zeroes_data=true".

Which both would allocate those blocks, instead of unmapping them,
in contrast with expectations.

LVM/DM thin does set discard_zeroes_data=0,
because it silently ignores discards to partial chunks.

We can work around this by checking the alignment first.
For unaligned (wrt. alignment and granularity) or too small discards,
we zero-out the initial (and/or) trailing unaligned partial chunks,
but discard all the aligned full chunks.

At least for LVM/DM thin, the result is effectively "discard_zeroes_data=1".

Arguably it should behave this way internally, by default,
and we'll try to make that happen.

But our workaround is still valid for already deployed setups,
and for other devices that may behave this way.

Setting discard-zeroes-if-aligned=yes will allow DRBD to use
discards, and to announce discard_zeroes_data=true, even on
backends that announce discard_zeroes_data=false.

Setting discard-zeroes-if-aligned=no will cause DRBD to always
fall-back to zero-out on the receiving side, and to not even
announce discard capabilities on the Primary, if the respective
backend announces discard_zeroes_data=false.

We used to ignore the discard_zeroes_data setting completely.
To not break established and expected behaviour, and suddenly
cause fstrim on thin-provisioned LVs to run out-of-space,
instead of freeing up space, the default value is "yes".

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: Introduce new disk config option rs-discard-granularity

2016-06-14T03:43:04+00:00

As long as the value is 0 the feature is disabled. With setting
it to a positive value, DRBD limits and aligns its resync requests
to the rs-discard-granularity setting. If the sync source detects
all zeros in such a block, the resync target discards the range
on disk.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: Backport the "status" command

2015-11-25T16:22:00+00:00

The status command originates the drbd9 code base. While for now we
keep the status information in /proc/drbd available, this commit
allows the user base to gracefully migrate their monitoring
infrastructure to the new status reporting interface.

In drbd9 no status information is exposed through /proc/drbd.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: Backport the "events2" command

2015-11-25T16:22:00+00:00

The events2 command originates from drbd-9 development. It features
more information but requires a incompatible change in output
format.
Therefore the previous events command continues to exist, the new
improved events2 command becomes available now.

This prepares the user-base for a later switch to the complete
drbd9 code base.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: New net configuration option socket-check-timeout

2014-07-10T16:35:01+00:00

In setups involving a DRBD-proxy and connections that experience a lot of
buffer-bloat it might be necessary to set ping-timeout to an
unusual high value. By default DRBD uses the same value to wait if a newly
established TCP-connection is stable. Since the DRBD-proxy is usually located
in the same data center such a long wait time may hinder DRBD's connect process.

In such setups socket-check-timeout should be set to
at least to the round trip time between DRBD and DRBD-proxy. I.e. in most
cases to 1.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg

drbd: implement csums-after-crash-only

2014-07-10T16:35:00+00:00

Checksum based resync trades CPU cycles for network bandwidth,
in situations where we expect much of the to-be-resynced blocks
to be actually identical on both sides already.

In a "network hickup" scenario, it won't help:
all to-be-resynced blocks will typically be different.

The use case is for the resync of *potentially* different blocks
after crash recovery -- the crash recovery had marked larger areas
(those covered by the activity log) as need-to-be-resynced,
just in case. Most of those blocks will be identical.

This option makes it possible to configure checksum based resync,
but only actually use it for the first resync after primary crash.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg

drbd: Define the size of res_opts->cpu_mask in a single place

2014-02-17T15:46:48+00:00

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Philipp Reisner

drbd: Improve some function and variable naming

2014-02-17T15:44:52+00:00

Rename functions
conn_destroy() -> drbd_destroy_connection(),
drbd_minor_destroy() -> drbd_destroy_device()
drbd_adm_add_minor() -> drbd_adm_add_minor()
drbd_adm_delete_minor() -> drbd_adm_del_minor()

Rename global variable minors to drbd_devices

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Philipp Reisner

drbd: Allow online change of al-stripes and al-stripe-size

2013-06-28T14:04:36+00:00

Allow to change the AL layout with an resize operation. For that
the reisze command gets two new fields: al_stripes and al_stripe_size.

In order to make the operation crash save:
1) Lock out all IO and MD-IO
2) Write the super block with MDF_PRIMARY_IND clear
3) write the bitmap to the new location (all zeros, since
   we allow only while connected)
4) Initialize the new AL-area
5) Write the super block with the restored MDF_PRIMARY_IND.
6) Unfreeze all IO

Since the AL-layout has no influence on the protocol, this operation
needs to be beforemed on both sides of a resource (if intended).

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Philipp Reisner 
Signed-off-by: Jens Axboe