mm: write_cache_pages terminate quickly
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>wifi-calibration
parent
515f4a037f
commit
d5482cdf8a
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@ -911,15 +911,24 @@ retry:
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for (i = 0; i < nr_pages; i++) {
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for (i = 0; i < nr_pages; i++) {
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struct page *page = pvec.pages[i];
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struct page *page = pvec.pages[i];
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/*
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* At this point, the page may be truncated or
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* invalidated (changing page->mapping to NULL), or
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* even swizzled back from swapper_space to tmpfs file
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* mapping. However, page->index will not change
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* because we have a reference on the page.
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*/
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if (page->index > end) {
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/*
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* can't be range_cyclic (1st pass) because
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* end == -1 in that case.
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*/
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done = 1;
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break;
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}
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done_index = page->index + 1;
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done_index = page->index + 1;
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/*
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* At this point we hold neither mapping->tree_lock nor
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* lock on the page itself: the page may be truncated or
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* invalidated (changing page->mapping to NULL), or even
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* swizzled back from swapper_space to tmpfs file
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* mapping
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*/
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lock_page(page);
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lock_page(page);
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/*
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/*
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@ -936,15 +945,6 @@ continue_unlock:
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continue;
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continue;
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}
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}
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if (page->index > end) {
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/*
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* can't be range_cyclic (1st pass) because
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* end == -1 in that case.
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*/
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done = 1;
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goto continue_unlock;
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}
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if (!PageDirty(page)) {
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if (!PageDirty(page)) {
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/* someone wrote it for us */
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/* someone wrote it for us */
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goto continue_unlock;
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goto continue_unlock;
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