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Tejun Heo 682aa8e1a6 writeback: implement unlocked_inode_to_wb transaction and use it for stat updates 
The mechanism for detecting whether an inode should switch its wb
(bdi_writeback) association is now in place.  This patch build the
framework for the actual switching.

This patch adds a new inode flag I_WB_SWITCHING, which has two
functions.  First, the easy one, it ensures that there's only one
switching in progress for a give inode.  Second, it's used as a
mechanism to synchronize wb stat updates.

The two stats, WB_RECLAIMABLE and WB_WRITEBACK, aren't event counters
but track the current number of dirty pages and pages under writeback
respectively.  As such, when an inode is moved from one wb to another,
the inode's portion of those stats have to be transferred together;
unfortunately, this is a bit tricky as those stat updates are percpu
operations which are performed without holding any lock in some
places.

This patch solves the problem in a similar way as memcg.  Each such
lockless stat updates are wrapped in transaction surrounded by
unlocked_inode_to_wb_begin/end().  During normal operation, they map
to rcu_read_lock/unlock(); however, if I_WB_SWITCHING is asserted,
mapping->tree_lock is grabbed across the transaction.

In turn, the switching path sets I_WB_SWITCHING and waits for a RCU
grace period to pass before actually starting to switch, which
guarantees that all stat update paths are synchronizing against
mapping->tree_lock.

This patch still doesn't implement the actual switching.

v3: Updated on top of the recent cancel_dirty_page() updates.
    unlocked_inode_to_wb_begin() now nests inside
    mem_cgroup_begin_page_stat() to match the locking order.

v2: The i_wb access transaction will be used for !stat accesses too.
    Function names and comments updated accordingly.

    s/inode_wb_stat_unlocked_{begin|end}/unlocked_inode_to_wb_{begin|end}/
    s/switch_wb/switch_wbs/

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
 		2015-06-02 08:40:20 -06:00
..
kasan mm/mempool.c: kasan: poison mempool elements 2015-04-15 16:35:20 -07:00
Kconfig mm: cma: debugfs interface 2015-04-14 16:49:00 -07:00
Kconfig.debug mm/debug_pagealloc: remove obsolete Kconfig options 2015-01-08 15:10:52 -08:00
Makefile mm: move memtest under mm 2015-04-14 16:49:06 -07:00
backing-dev.c writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb() 2015-06-02 08:39:08 -06:00
balloon_compaction.c mm/balloon_compaction: fix deflation when compaction is disabled 2014-10-29 16:33:15 -07:00
bootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
cleancache.c cleancache: remove limit on the number of cleancache enabled filesystems 2015-04-14 16:49:03 -07:00
cma.c mm: cma: add trace events for CMA allocations and freeings 2015-04-15 16:35:19 -07:00
cma.h mm: cma: allocation trigger 2015-04-14 16:49:00 -07:00
cma_debug.c mm/cma_debug.c: remove blank lines before DEFINE_SIMPLE_ATTRIBUTE() 2015-04-15 16:35:20 -07:00
compaction.c mm/compaction.c: fix "suitable_migration_target() unused" warning 2015-04-15 16:35:20 -07:00
debug-pagealloc.c mm/debug-pagealloc: make debug-pagealloc boottime configurable 2014-12-13 12:42:48 -08:00
debug.c mm: account pmd page tables to the process 2015-02-11 17:06:04 -08:00
dmapool.c mm/dmapool.c: fixed a brace coding style issue 2014-10-09 22:26:00 -04:00
early_ioremap.c mm: create generic early_ioremap() support 2014-04-07 16:36:15 -07:00
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap.c writeback: implement unlocked_inode_to_wb transaction and use it for stat updates 2015-06-02 08:40:20 -06:00
frontswap.c mm/frontswap.c: fix the condition in BUG_ON 2014-12-10 17:41:08 -08:00
gup.c mm: use READ_ONCE() for non-scalar types 2015-04-15 16:35:18 -07:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c thp: cleanup khugepaged startup 2015-04-15 16:35:19 -07:00
hugetlb.c mm: hugetlb: cleanup using paeg_huge_active() 2015-04-15 16:35:19 -07:00
hugetlb_cgroup.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
hwpoison-inject.c mm/hwpoison-inject.c: remove unnecessary null test before debugfs_remove_recursive 2014-08-06 18:01:19 -07:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c kmemleak: disable kasan instrumentation for kmemleak 2015-02-13 21:21:41 -08:00
ksm.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
list_lru.c memcg: reparent list_lrus and free kmemcg_id on css offline 2015-02-12 18:54:10 -08:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c writeback: separate out include/linux/backing-dev-defs.h 2015-06-02 08:33:34 -06:00
memblock.c mm/memblock.c: add debug output for memblock_add() 2015-04-15 16:35:19 -07:00
memcontrol.c writeback: implement memcg writeback domain based throttling 2015-06-02 08:38:13 -06:00
memory-failure.c mm: hugetlb: introduce page_huge_active 2015-04-15 16:35:19 -07:00
memory.c mm: new pfn_mkwrite same as page_mkwrite for VM_PFNMAP 2015-04-15 16:35:20 -07:00
memory_hotplug.c mm: hugetlb: cleanup using paeg_huge_active() 2015-04-15 16:35:19 -07:00
mempolicy.c mm, thp: really limit transparent hugepage allocation to local node 2015-04-14 16:49:03 -07:00
mempool.c mm/mempool.c: kasan: poison mempool elements 2015-04-15 16:35:20 -07:00
memtest.c memtest: use phys_addr_t for physical addresses 2015-04-14 16:49:06 -07:00
migrate.c mm/migrate: check-before-clear PageSwapCache 2015-04-15 16:35:17 -07:00
mincore.c mincore: apply page table walker on do_mincore() 2015-02-11 17:06:06 -08:00
mlock.c mm: move mm_populate()-related code to mm/gup.c 2015-04-14 16:49:00 -07:00
mm_init.c mm/mm_init.c: mark mminit_loglevel __meminitdata 2015-02-12 18:54:11 -08:00
mmap.c mm/mmap.c: use while instead of if+goto 2015-04-15 16:35:19 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mmu_notifier: add the callback for mmu_notifier_invalidate_range() 2014-11-13 13:46:09 +11:00
mmzone.c mm: microoptimize zonelist operations 2015-02-11 17:06:02 -08:00
mprotect.c mm: numa: preserve PTE write permissions across a NUMA hinting fault 2015-03-25 16:20:31 -07:00
mremap.c mm/mremap.c: clean up goto just return ERR_PTR 2015-04-15 16:35:18 -07:00
msync.c mm: remove rest usage of VM_NONLINEAR and pte_file() 2015-02-10 14:30:31 -08:00
nobootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
nommu.c nommu: use __vfs_read() 2015-04-11 22:27:56 -04:00
oom_kill.c mm/oom_kill.c: fix typo in comment 2015-04-15 16:35:16 -07:00
page-writeback.c writeback: implement unlocked_inode_to_wb transaction and use it for stat updates 2015-06-02 08:40:20 -06:00
page_alloc.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
page_counter.c mm: page_counter: pull "-1" handling out of page_counter_memparse() 2015-02-11 17:06:02 -08:00
page_ext.c mm/page_owner: keep track of page owners 2014-12-13 12:42:48 -08:00
page_io.c suspend: simplify block I/O handling 2015-05-19 09:19:59 -06:00
page_isolation.c mm/page_alloc.c: call kernel_map_pages in unset_migrateype_isolate 2015-03-25 16:20:30 -07:00
page_owner.c mm/page_owner.c: remove unnecessary stack_trace field 2015-02-11 17:06:07 -08:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated 2014-09-02 14:46:05 -04:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c percpu: Fix trivial typos in comments 2015-03-24 13:41:54 -04:00
pgtable-generic.c mm: convert p[te|md]_mknonnuma and remaining page table manipulations 2015-02-12 18:54:08 -08:00
process_vm_access.c process_vm_access: switch to {compat_,}import_iovec() 2015-04-11 22:27:12 -04:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
rmap.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
shmem.c VFS: assorted weird filesystems: d_inode() annotations 2015-04-15 15:06:58 -04:00
slab.c mm: remove GFP_THISNODE 2015-04-14 16:49:03 -07:00
slab.h slub: make dead caches discard free slabs immediately 2015-02-12 18:54:10 -08:00
slab_common.c mm: slub: add kernel address sanitizer support for slub allocator 2015-02-13 21:21:41 -08:00
slob.c slob: make slob_alloc_node() static and remove EXPORT_SYMBOL() 2015-04-14 16:48:59 -07:00
slub.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap.c mm: don't call __page_cache_release for hugetlb 2015-04-15 16:35:19 -07:00
swap_cgroup.c mm: page_cgroup: rename file to mm/swap_cgroup.c 2014-12-10 17:41:09 -08:00
swap_state.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
swapfile.c mm: remove rest of ACCESS_ONCE() usages 2015-04-15 16:35:18 -07:00
truncate.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
util.c mm: uninline and cleanup page-mapping related helpers 2015-04-15 16:35:19 -07:00
vmacache.c mm,vmacache: count number of system-wide flushes 2014-12-13 12:42:48 -08:00
vmalloc.c mm/vmalloc: get rid of dirty bitmap inside vmap_block structure 2015-04-15 16:35:18 -07:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use 2015-06-02 08:38:13 -06:00
vmstat.c vmstat: Reduce time interval to stat update on idle cpu 2015-02-11 17:06:07 -08:00
workingset.c list_lru: add helpers to isolate items 2015-02-12 18:54:10 -08:00
zbud.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00
zpool.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00
zsmalloc.c zsmalloc: remove extra cond_resched() in __zs_compact 2015-04-15 16:35:22 -07:00
zswap.c mm/zpool: add name argument to create zpool 2015-02-12 18:54:12 -08:00