[PATCH v2] enable all tmem backends to be built and loaded as modules.

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There are also some patch I wrote up that are based on this patchset
that I will post soonish.

I copying here what Dan mentioned with some modifications by me:

 Since various parts of transcendent memory ("tmem") [1] were first posted in
 2009, reviewers have suggested that various tmem features should be built
 as a module and enabled by loading the module, rather than the current clunky
 method of compiling as a built-in and enabling via boot parameter.  Due
 to certain tmem initialization steps, that was not feasible at the time.
 
 [1] http://lwn.net/Articles/454795/
 
 This patchset allows each of the three merged transcendent memory
 backends (zcache, ramster, Xen tmem) to be used as modules by first
 enabling transcendent memory frontends (cleancache, frontswap) to deal
 with "lazy initialization" and, second, by adding the necessary code for
 the backends to be built and loaded as modules.
 
 The original mechanism to enable tmem backends -- namely to hardwire
 them into the kernel and select/enable one with a kernel boot
 parameter --  is retained but should be considered deprecated.  When
 backends are loaded as modules, certain knobs will now be
 properly selected via module_params rather than via undocumented
 kernel boot parameters.  Note that module UNloading is not yet
 supported as it is lower priority and will require significant
 additional work.
 
 The lazy initialization support is necessary because filesystems
 and swap devices are normally mounted early in boot and these
 activites normally trigger tmem calls to setup certain data structures;
 if the respective cleancache/frontswap ops are not yet registered
 by a back end, the tmem setup would fail for these devices and
 cleancache/frontswap would never be enabled for them which limits
 much of the value of tmem in many system configurations.  Lazy
 initialization records the necessary information in cleancache/frontswap
 data structures and "replays" it after the ops are registered
 to ensure that all filesystems and swap devices can benefit from
 the loaded tmem backend.
 
 [PATCH 1/8] mm: cleancache: lazy initialization to allow tmem
 [PATCH 2/8] mm: frontswap: lazy initialization to allow tmem

 Patches 1 and 2 are the original [2] patches to cleancache and frontswap
 proposed by Erlangen University, but rebased to 3.7-rcN plus a couple
 of bug fixes I found necessary to run properly + extra review comments.
 
 [2] http://www.spinics.net/lists/linux-mm/msg31490.html

 The other two:
 [PATCH 3/8] frontswap: Make frontswap_init use a pointer for the
 [PATCH 4/8] cleancache: Make cleancache_init use a pointer for the
 do a bit of code cleanup that can be done to make it easier to
 read and also remove some of the bools.
 
 [PATCH 5/8] staging: zcache2+ramster: enable ramster to be
 Enables module support for zcache2.  Zsmalloc support
 has not yet been merged into zcache2 but, once merged, could now
 easily be selected via a module_param.
 
 [PATCH 6/8] staging: zcache2+ramster: enable zcache2 to be
 Enables module support for ramster.  Ramster will now be
 enabled with a module_param to zcache2.
 
 [PATCH 7/8] xen: tmem: enable Xen tmem shim to be built/loaded as a
 [PATCH 8/8] xen/tmem: Remove the subsys call.
 Enables module support for the Xen tmem shim.  Xen self-ballooning and
 frontswap-selfshrinking are also "lazily"
 initialized when the Xen tmem shim is loaded as a module, unless
 explicitly disabled by module_params.


Dan Magenheimer (5):
      mm: cleancache: lazy initialization to allow tmem backends to build/run as modules
      mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
      staging: zcache2+ramster: enable ramster to be built/loaded as a module
      staging: zcache2+ramster: enable zcache2 to be built/loaded as a module
      xen: tmem: enable Xen tmem shim to be built/loaded as a module

Konrad Rzeszutek Wilk (3):
      frontswap: Make frontswap_init use a pointer for the ops.
      cleancache: Make cleancache_init use a pointer for the ops
      xen/tmem: Remove the subsys call.


 drivers/staging/ramster/Kconfig                    |    6 +-
 drivers/staging/ramster/Makefile                   |   11 +-
 drivers/staging/ramster/ramster.h                  |    6 +-
 drivers/staging/ramster/ramster/nodemanager.c      |    9 +-
 drivers/staging/ramster/ramster/ramster.c          |   29 +++-
 drivers/staging/ramster/ramster/ramster.h          |    2 +-
 .../staging/ramster/ramster/ramster_nodemanager.h  |    2 +
 drivers/staging/ramster/tmem.c                     |    6 +-
 drivers/staging/ramster/tmem.h                     |    8 +-
 drivers/staging/ramster/zcache-main.c              |   63 ++++++--
 drivers/staging/ramster/zcache.h                   |    2 +-
 drivers/staging/zcache/zcache-main.c               |   16 +-
 drivers/xen/Kconfig                                |    4 +-
 drivers/xen/tmem.c                                 |   50 ++++--
 drivers/xen/xen-selfballoon.c                      |   13 +-
 include/linux/cleancache.h                         |    2 +-
 include/linux/frontswap.h                          |    2 +-
 include/xen/tmem.h                                 |    8 +
 mm/cleancache.c                                    |  167 +++++++++++++++++---
 mm/frontswap.c                                     |   78 +++++++--
 20 files changed, 371 insertions(+), 113 deletions(-)
>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
Subject: [PATCH v2] enable all tmem backends to be built and loaded as modules.
Changelog since [v1: https://lkml.org/lkml/2012/10/31/403]
 - Addressed various people comments (most of them in the frontswap code).
 - Fixed up compile issues.

There are also some patch I wrote up that are based on this patchset
that I will post soonish.

I copying here what Dan mentioned with some modifications by me:

 Since various parts of transcendent memory ("tmem") [1] were first posted in
 2009, reviewers have suggested that various tmem features should be built
 as a module and enabled by loading the module, rather than the current clunky
 method of compiling as a built-in and enabling via boot parameter.  Due
 to certain tmem initialization steps, that was not feasible at the time.
 
 [1] http://lwn.net/Articles/454795/
 
 This patchset allows each of the three merged transcendent memory
 backends (zcache, ramster, Xen tmem) to be used as modules by first
 enabling transcendent memory frontends (cleancache, frontswap) to deal
 with "lazy initialization" and, second, by adding the necessary code for
 the backends to be built and loaded as modules.
 
 The original mechanism to enable tmem backends -- namely to hardwire
 them into the kernel and select/enable one with a kernel boot
 parameter --  is retained but should be considered deprecated.  When
 backends are loaded as modules, certain knobs will now be
 properly selected via module_params rather than via undocumented
 kernel boot parameters.  Note that module UNloading is not yet
 supported as it is lower priority and will require significant
 additional work.
 
 The lazy initialization support is necessary because filesystems
 and swap devices are normally mounted early in boot and these
 activites normally trigger tmem calls to setup certain data structures;
 if the respective cleancache/frontswap ops are not yet registered
 by a back end, the tmem setup would fail for these devices and
 cleancache/frontswap would never be enabled for them which limits
 much of the value of tmem in many system configurations.  Lazy
 initialization records the necessary information in cleancache/frontswap
 data structures and "replays" it after the ops are registered
 to ensure that all filesystems and swap devices can benefit from
 the loaded tmem backend.
 
 [PATCH 1/8] mm: cleancache: lazy initialization to allow tmem
 [PATCH 2/8] mm: frontswap: lazy initialization to allow tmem

 Patches 1 and 2 are the original [2] patches to cleancache and frontswap
 proposed by Erlangen University, but rebased to 3.7-rcN plus a couple
 of bug fixes I found necessary to run properly + extra review comments.
 
 [2] http://www.spinics.net/lists/linux-mm/msg31490.html

 The other two:
 [PATCH 3/8] frontswap: Make frontswap_init use a pointer for the
 [PATCH 4/8] cleancache: Make cleancache_init use a pointer for the
 do a bit of code cleanup that can be done to make it easier to
 read and also remove some of the bools.
 
 [PATCH 5/8] staging: zcache2+ramster: enable ramster to be
 Enables module support for zcache2.  Zsmalloc support
 has not yet been merged into zcache2 but, once merged, could now
 easily be selected via a module_param.
 
 [PATCH 6/8] staging: zcache2+ramster: enable zcache2 to be
 Enables module support for ramster.  Ramster will now be
 enabled with a module_param to zcache2.
 
 [PATCH 7/8] xen: tmem: enable Xen tmem shim to be built/loaded as a
 [PATCH 8/8] xen/tmem: Remove the subsys call.
 Enables module support for the Xen tmem shim.  Xen self-ballooning and
 frontswap-selfshrinking are also "lazily"
 initialized when the Xen tmem shim is loaded as a module, unless
 explicitly disabled by module_params.


Dan Magenheimer (5):
      mm: cleancache: lazy initialization to allow tmem backends to build/run as modules
      mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
      staging: zcache2+ramster: enable ramster to be built/loaded as a module
      staging: zcache2+ramster: enable zcache2 to be built/loaded as a module
      xen: tmem: enable Xen tmem shim to be built/loaded as a module

Konrad Rzeszutek Wilk (3):
      frontswap: Make frontswap_init use a pointer for the ops.
      cleancache: Make cleancache_init use a pointer for the ops
      xen/tmem: Remove the subsys call.


 drivers/staging/ramster/Kconfig                    |    6 +-
 drivers/staging/ramster/Makefile                   |   11 +-
 drivers/staging/ramster/ramster.h                  |    6 +-
 drivers/staging/ramster/ramster/nodemanager.c      |    9 +-
 drivers/staging/ramster/ramster/ramster.c          |   29 +++-
 drivers/staging/ramster/ramster/ramster.h          |    2 +-
 .../staging/ramster/ramster/ramster_nodemanager.h  |    2 +
 drivers/staging/ramster/tmem.c                     |    6 +-
 drivers/staging/ramster/tmem.h                     |    8 +-
 drivers/staging/ramster/zcache-main.c              |   63 ++++++--
 drivers/staging/ramster/zcache.h                   |    2 +-
 drivers/staging/zcache/zcache-main.c               |   16 +-
 drivers/xen/Kconfig                                |    4 +-
 drivers/xen/tmem.c                                 |   50 ++++--
 drivers/xen/xen-selfballoon.c                      |   13 +-
 include/linux/cleancache.h                         |    2 +-
 include/linux/frontswap.h                          |    2 +-
 include/xen/tmem.h                                 |    8 +
 mm/cleancache.c                                    |  167 +++++++++++++++++---
 mm/frontswap.c                                     |   78 +++++++--
 20 files changed, 371 insertions(+), 113 deletions(-)
>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: [PATCH] zcache2 cleanups (s/int/bool/ + debugfs move).
In-Reply-To: 
Changelog since rfc: https://lkml.org/lkml/2012/11/5/549
 - Added Reviewed-by from Dan.

This patchset depends on the recently posted V2 of making the
frontswap/cleancache backends be module capable:
 http://mid.gmane.org/1352919432-9699-1-git-send-email-konrad.wilk@xxxxxxxxxx

I think that once the V2 is OK I will combine this patchset along
with the V2 and send the whole thing to GregKH? Or perhaps just
if Greg is Ok I will do via my tree.

This is a copy of what I wrote in the RFC posting:

Looking at the zcache2 code there were a couple of things that I thought
would make sense to move out of the code. For one thing it makes it easier
to read, and for anoter - it can be cleanly compiled out. It also allows
to have a clean seperation of counters that we _need_ vs the optional ones.
Which means that in the future we could get rid of the optional ones.

It fixes some outstanding compile warnings, cleans
up some of the code, and rips out the debug counters out of zcache-main.c
and sticks them in a debug.c file.

I was hoping it would end up with less code, but sadly it ended up with
a bit more due to the empty non-debug functions - but the code is easier
to read.


 drivers/staging/ramster/Kconfig       |    8 +
 drivers/staging/ramster/Makefile      |    1 +
 drivers/staging/ramster/debug.c       |   66 +++++++
 drivers/staging/ramster/debug.h       |  229 ++++++++++++++++++++++
 drivers/staging/ramster/zcache-main.c |  336 +++++++--------------------------
 5 files changed, 370 insertions(+), 270 deletions(-)


Konrad Rzeszutek Wilk (11):
      zcache: Provide accessory functions for counter increase
      zcache: Provide accessory functions for counter decrease.
      zcache: The last of the atomic reads has now an accessory function.
      zcache: Fix compile warnings due to usage of debugfs_create_size_t
      zcache: Make the debug code use pr_debug
      zcache: Move debugfs code out of zcache-main.c file.
      zcache: Use an array to initialize/use debugfs attributes.
      zcache: Move the last of the debugfs counters out
      zcache: Allow to compile if ZCACHE_DEBUG and !DEBUG_FS
      zcache: Module license is defined twice.
      zcache: Coalesce all debug under CONFIG_ZCACHE2_DEBUG

>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
Subject: [PATCH] zcache2 cleanups (s/int/bool/ + debugfs move).
Changelog since rfc: https://lkml.org/lkml/2012/11/5/549
 - Added Reviewed-by from Dan.

This patchset depends on the recently posted V2 of making the
frontswap/cleancache backends be module capable:
 http://mid.gmane.org/1352919432-9699-1-git-send-email-konrad.wilk@xxxxxxxxxx

I think that once the V2 is OK I will combine this patchset along
with the V2 and send the whole thing to GregKH? Or perhaps just
if Greg is Ok I will do via my tree.

This is a copy of what I wrote in the RFC posting:

Looking at the zcache2 code there were a couple of things that I thought
would make sense to move out of the code. For one thing it makes it easier
to read, and for anoter - it can be cleanly compiled out. It also allows
to have a clean seperation of counters that we _need_ vs the optional ones.
Which means that in the future we could get rid of the optional ones.

It fixes some outstanding compile warnings, cleans
up some of the code, and rips out the debug counters out of zcache-main.c
and sticks them in a debug.c file.

I was hoping it would end up with less code, but sadly it ended up with
a bit more due to the empty non-debug functions - but the code is easier
to read.


 drivers/staging/ramster/Kconfig       |    8 +
 drivers/staging/ramster/Makefile      |    1 +
 drivers/staging/ramster/debug.c       |   66 +++++++
 drivers/staging/ramster/debug.h       |  229 ++++++++++++++++++++++
 drivers/staging/ramster/zcache-main.c |  336 +++++++--------------------------
 5 files changed, 370 insertions(+), 270 deletions(-)


Konrad Rzeszutek Wilk (11):
      zcache: Provide accessory functions for counter increase
      zcache: Provide accessory functions for counter decrease.
      zcache: The last of the atomic reads has now an accessory function.
      zcache: Fix compile warnings due to usage of debugfs_create_size_t
      zcache: Make the debug code use pr_debug
      zcache: Move debugfs code out of zcache-main.c file.
      zcache: Use an array to initialize/use debugfs attributes.
      zcache: Move the last of the debugfs counters out
      zcache: Allow to compile if ZCACHE_DEBUG and !DEBUG_FS
      zcache: Module license is defined twice.
      zcache: Coalesce all debug under CONFIG_ZCACHE2_DEBUG

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