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authorNick Piggin <npiggin@suse.de>2009-01-06 17:39:11 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 18:59:00 -0500
commitd5482cdf8a0aacb1e6468a97d5544f5829c8d8c4 (patch)
tree3565702c805deecd51e32ed1458f567a0064815d /mm/page-writeback.c
parent515f4a037fb9ab736f8bad733fcd2ffd350cf265 (diff)
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>
Diffstat (limited to 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c32
1 files changed, 16 insertions, 16 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2e8c2b01d5d5..0d986c13d473 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -911,15 +911,24 @@ retry:
911 for (i = 0; i < nr_pages; i++) { 911 for (i = 0; i < nr_pages; i++) {
912 struct page *page = pvec.pages[i]; 912 struct page *page = pvec.pages[i];
913 913
914 done_index = page->index + 1;
915
916 /* 914 /*
917 * At this point we hold neither mapping->tree_lock nor 915 * At this point, the page may be truncated or
918 * lock on the page itself: the page may be truncated or 916 * invalidated (changing page->mapping to NULL), or
919 * invalidated (changing page->mapping to NULL), or even 917 * even swizzled back from swapper_space to tmpfs file
920 * swizzled back from swapper_space to tmpfs file 918 * mapping. However, page->index will not change
921 * mapping 919 * because we have a reference on the page.
922 */ 920 */
921 if (page->index > end) {
922 /*
923 * can't be range_cyclic (1st pass) because
924 * end == -1 in that case.
925 */
926 done = 1;
927 break;
928 }
929
930 done_index = page->index + 1;
931
923 lock_page(page); 932 lock_page(page);
924 933
925 /* 934 /*
@@ -936,15 +945,6 @@ continue_unlock:
936 continue; 945 continue;
937 } 946 }
938 947
939 if (page->index > end) {
940 /*
941 * can't be range_cyclic (1st pass) because
942 * end == -1 in that case.
943 */
944 done = 1;
945 goto continue_unlock;
946 }
947
948 if (!PageDirty(page)) { 948 if (!PageDirty(page)) {
949 /* someone wrote it for us */ 949 /* someone wrote it for us */
950 goto continue_unlock; 950 goto continue_unlock;