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* frontswap: get rid of swap_lock dependencyMinchan Kim2013-04-301-8/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | Frontswap initialization routine depends on swap_lock, which want to be atomic about frontswap's first appearance. IOW, frontswap is not present and will fail all calls OR frontswap is fully functional but if new swap_info_struct isn't registered by enable_swap_info, swap subsystem doesn't start I/O so there is no race between init procedure and page I/O working on frontswap. So let's remove unnecessary swap_lock dependency. Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Signed-off-by: Minchan Kim <minchan@kernel.org> [v1: Rebased on my branch, reworked to work with backends loading late] [v2: Added a check for !map] [v3: Made the invalidate path follow the init path] [v4: Address comments by Wanpeng Li <liwanp@linux.vnet.ibm.com>] Signed-off-by: Konrad Rzeszutek Wilk <konrad@darnok.org> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: frontswap: cleanup codeBob Liu2013-04-301-27/+30
| | | | | | | | | | | | | | | | | | | | After allowing tmem backends to build/run as modules, frontswap_enabled always true if defined CONFIG_FRONTSWAP. But frontswap_test() depends on whether backend is registered, mv it into frontswap.c using fronstswap_ops to make the decision. frontswap_set/clear are not used outside frontswap, so don't export them. Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: make frontswap_init use a pointer for the opsKonrad Rzeszutek Wilk2013-04-301-20/+18
| | | | | | | | | | | | | | | | | This simplifies the code in the frontswap - we can get rid of the 'backend_registered' test and instead check against frontswap_ops. [v1: Rebase on top of 703ba7fe5e0 (ramster->zcache move] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: frontswap: lazy initialization to allow tmem backends to build/run as ↵Dan Magenheimer2013-04-301-10/+84
| | | | | | | | | | | | | | | | | | | | | | | | | | | | modules With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to be built/loaded as modules rather than built-in and enabled by a boot parameter, this patch provides "lazy initialization", allowing backends to register to frontswap even after swapon was run. Before a backend registers all calls to init are recorded and the creation of tmem_pools delayed until a backend registers or until a frontswap store is attempted. Signed-off-by: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Florian Schmaus <fschmaus@gmail.com> Signed-off-by: Andor Daam <andor.daam@googlemail.com> Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> [v1: Fixes per Seth Jennings suggestions] [v2: Removed FRONTSWAP_HAS_.. ] [v3: Fix up per Bob Liu <lliubbo@gmail.com> recommendations] [v4: Fix up per Andrew's comments] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: support exclusive gets if tmem backend is capableDan Magenheimer2012-09-211-1/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tmem, as originally specified, assumes that "get" operations performed on persistent pools never flush the page of data out of tmem on a successful get, waiting instead for a flush operation. This is intended to mimic the model of a swap disk, where a disk read is non-destructive. Unlike a disk, however, freeing up the RAM can be valuable. Over the years that frontswap was in the review process, several reviewers (and notably Hugh Dickins in 2010) pointed out that this would result, at least temporarily, in two copies of the data in RAM: one (compressed for zcache) copy in tmem, and one copy in the swap cache. We wondered if this could be done differently, at least optionally. This patch allows tmem backends to instruct the frontswap code that this backend performs exclusive gets. Zcache2 already contains hooks to support this feature. Other backends are completely unaffected unless/until they are updated to support this feature. While it is not clear that exclusive gets are a performance win on all workloads at all times, this small patch allows for experimentation by backends. P.S. Let's not quibble about the naming of "get" vs "read" vs "load" etc. The naming is currently horribly inconsistent between cleancache and frontswap and existing tmem backends, so will need to be straightened out as a separate patch. "Get" is used by the tmem architecture spec, existing backends, and all documentation and presentation material so I am using it in this patch. Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: fix a wrong if condition in frontswap_shrinkZhenzhong Duan2012-09-211-2/+7
| | | | | | | | | | | | pages_to_unuse is set to 0 to unuse all frontswap pages But that doesn't happen since a wrong condition in frontswap_shrink cancel it. -v2: Add comment to explain return value of __frontswap_shrink, as suggested by Dan Carpenter, thanks Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm/frontswap: fix uninit'ed variable warningSeth Jennings2012-08-131-1/+1
| | | | | | | | | | Fixes uninitialized variable warning on 'type' in frontswap_shrink(). type is set before use by __frontswap_unuse_pages() called by __frontswap_shrink() called by frontswap_shrink() before use by try_to_unuse(). Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm/frontswap: cleanup doc and comment errorWanpeng Li2012-07-231-1/+1
| | | | | Signed-off-by: Wanpeng Li <liwp.linux@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove unneeded headersSasha Levin2012-07-231-4/+0
| | | | | | Signed-off-by: Sasha Levin <levinsasha928@gmail.com> [v1: Rebased with tracing removed] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out function to clear a page outSasha Levin2012-07-191-6/+9
| | | | | Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove unnecessary check during initializationSasha Levin2012-06-111-2/+1
| | | | | | | | | | | | The check whether frontswap is enabled or not is done in the API functions in the frontswap header, before they are passed to the internal double-underscored frontswap functions. Remove the check from __frontswap_init for consistency. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: make all branches of if statement in put page consistentSasha Levin2012-06-111-5/+5
| | | | | | | | | Currently it has a complex structure where different things are compared at each branch. Simplify that and make both branches look similar. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split frontswap_shrink further to simplify lockingSasha Levin2012-06-111-15/+21
| | | | | | | | | | Split frontswap_shrink to simplify the locking in the original code. Also, assert that the function that was split still runs under the swap spinlock. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out __frontswap_unuse_pagesSasha Levin2012-06-111-20/+39
| | | | | | | | | | | | An attempt at making frontswap_shrink shorter and more readable. This patch splits out walking through the swap list to find an entry with enough pages to unuse. Also, assert that the internal __frontswap_unuse_pages is called under swap lock, since that part of code was previously directly happen inside the lock. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out __frontswap_curr_pagesSasha Levin2012-06-111-11/+17
| | | | | | | | | | Code was duplicated in two functions, clean it up. Also, assert that the deduplicated code runs under the swap spinlock. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: trivial coding convention issuesSasha Levin2012-06-111-3/+4
| | | | | | Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove casting from function calls through ops structureSasha Levin2012-06-111-5/+5
| | | | | | | | Removes unneeded casts. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* frontswap: s/put_page/store/g s/get_page/loadKonrad Rzeszutek Wilk2012-05-151-28/+28
| | | | | | | Sounds so much more natural. Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: core frontswap functionalityDan Magenheimer2012-05-151-0/+314
This patch, 3of4, provides the core frontswap code that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: mm/frontswap.c [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v11: sjenning@linux.vnet.ibm.com: s/puts/failed_puts/] [v10: sjenning@linux.vnet.ibm.com: fix debugfs calls on 32-bit] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v9: akpm@linux-foundation.org: mark some statics __read_mostly] [v9: akpm@linux-foundation.org: add clarifying comments] [v9: akpm@linux-foundation.org: no need to loop repeating try_to_unuse] [v9: error27@gmail.com: remove superfluous check for NULL] [v8: rebase to 3.0-rc4] [v8: kamezawa.hiroyu@jp.fujitsu.com: add comment to clarify find_next_to_unuse] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: use new static inlines, no-ops if not config'd] [v6: rebase to 3.1-rc1] [v6: lliubbo@gmail.com: use vzalloc] [v6: lliubbo@gmail.com: fix null pointer deref if vzalloc fails] [v6: konrad.wilk@oracl.com: various checks and code clarifications/comments] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> [v12: Squashed s/flush/invalidate/ in] [v15: A bit of cleanup and seperate DEBUGFS] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
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