Messages in this thread Patch in this message | | | Date | Thu, 22 Jan 2009 17:13:01 -0800 | From | Greg KH <> | Subject | [patch 40/46] mm: write_cache_pages terminate quickly |
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2.6.28-stable review patch. If anyone has any objections, please let us know.
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From: Nick Piggin <npiggin@suse.de>
commit d5482cdf8a0aacb1e6468a97d5544f5829c8d8c4 upstream.
Terminate the write_cache_pages loop upon encountering the first page past end, without locking the page. Pages cannot have their index change when we have a reference on them (truncate, eg truncate_inode_pages_range performs the same check without the page lock).
Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/page-writeback.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-)
--- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -911,15 +911,24 @@ retry: for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; - done_index = page->index + 1; - /* - * At this point we hold neither mapping->tree_lock nor - * lock on the page itself: the page may be truncated or - * invalidated (changing page->mapping to NULL), or even - * swizzled back from swapper_space to tmpfs file - * mapping + * At this point, the page may be truncated or + * invalidated (changing page->mapping to NULL), or + * even swizzled back from swapper_space to tmpfs file + * mapping. However, page->index will not change + * because we have a reference on the page. */ + if (page->index > end) { + /* + * can't be range_cyclic (1st pass) because + * end == -1 in that case. + */ + done = 1; + break; + } + + done_index = page->index + 1; + lock_page(page); /* @@ -936,15 +945,6 @@ continue_unlock: continue; } - if (page->index > end) { - /* - * can't be range_cyclic (1st pass) because - * end == -1 in that case. - */ - done = 1; - goto continue_unlock; - } - if (!PageDirty(page)) { /* someone wrote it for us */ goto continue_unlock;
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