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| author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2015-04-15 00:45:27 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-15 01:49:01 +0200 |
| commit | b9ea25152e56365ce149b9a39637cd7a16eec556 (patch) | |
| tree | e8ab83d71a0bea5330d38e77e948170c0054d2a3 /mm/filemap.c | |
| parent | mm: incorporate zero pages into transparent huge pages (diff) | |
| download | linux-b9ea25152e56365ce149b9a39637cd7a16eec556.tar.xz linux-b9ea25152e56365ce149b9a39637cd7a16eec556.zip | |
page_writeback: clean up mess around cancel_dirty_page()
This patch replaces cancel_dirty_page() with a helper function
account_page_cleaned() which only updates counters. It's called from
truncate_complete_page() and from try_to_free_buffers() (hack for ext3).
Page is locked in both cases, page-lock protects against concurrent
dirtiers: see commit 2d6d7f982846 ("mm: protect set_page_dirty() from
ongoing truncation").
Delete_from_page_cache() shouldn't be called for dirty pages, they must
be handled by caller (either written or truncated). This patch treats
final dirty accounting fixup at the end of __delete_from_page_cache() as
a debug check and adds WARN_ON_ONCE() around it. If something removes
dirty pages without proper handling that might be a bug and unwritten
data might be lost.
Hugetlbfs has no dirty pages accounting, ClearPageDirty() is enough
here.
cancel_dirty_page() in nfs_wb_page_cancel() is redundant. This is
helper for nfs_invalidate_page() and it's called only in case complete
invalidation.
The mess was started in v2.6.20 after commits 46d2277c796f ("Clean up
and make try_to_free_buffers() not race with dirty pages") and
3e67c0987d75 ("truncate: clear page dirtiness before running
try_to_free_buffers()") first was reverted right in v2.6.20 in commit
ecdfc9787fe5 ("Resurrect 'try_to_free_buffers()' VM hackery"), second in
v2.6.25 commit a2b345642f53 ("Fix dirty page accounting leak with ext3
data=journal").
Custom fixes were introduced between these points. NFS in v2.6.23, commit
1b3b4a1a2deb ("NFS: Fix a write request leak in nfs_invalidate_page()").
Kludge in __delete_from_page_cache() in v2.6.24, commit 3a6927906f1b ("Do
dirty page accounting when removing a page from the page cache"). Since
v2.6.25 all of them are redundant.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index ad7242043bdb..434dba317400 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -203,16 +203,15 @@ void __delete_from_page_cache(struct page *page, void *shadow) BUG_ON(page_mapped(page)); /* - * Some filesystems seem to re-dirty the page even after - * the VM has canceled the dirty bit (eg ext3 journaling). + * At this point page must be either written or cleaned by truncate. + * Dirty page here signals a bug and loss of unwritten data. * - * Fix it up by doing a final dirty accounting check after - * having removed the page entirely. + * This fixes dirty accounting after removing the page entirely but + * leaves PageDirty set: it has no effect for truncated page and + * anyway will be cleared before returning page into buddy allocator. */ - if (PageDirty(page) && mapping_cap_account_dirty(mapping)) { - dec_zone_page_state(page, NR_FILE_DIRTY); - dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE); - } + if (WARN_ON_ONCE(PageDirty(page))) + account_page_cleaned(page, mapping); } /** |