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authorNick Piggin <npiggin@suse.de>2009-01-07 01:39:09 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-07 02:58:59 +0300
commit5a3d5c9813db56a75934eb1015367fda23a8b0b4 (patch)
tree656b43b3982a6513467e9a3191377429bb9f45f1 /mm/page-writeback.c
parent05fe478dd04e02fa230c305ab9b5616669821dd3 (diff)
downloadlinux-5a3d5c9813db56a75934eb1015367fda23a8b0b4.tar.xz
mm: write_cache_pages cleanups
Get rid of some complex expressions from flow control statements, add a comment, remove some duplicate code. 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.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5edca676e2c3..c3fb38b1ea43 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -899,11 +899,14 @@ int write_cache_pages(struct address_space *mapping,
}
retry:
done_index = index;
- while (!done && (index <= end) &&
- (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
- PAGECACHE_TAG_DIRTY,
- min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
- unsigned i;
+ while (!done && (index <= end)) {
+ int i;
+
+ nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+ PAGECACHE_TAG_DIRTY,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+ if (nr_pages == 0)
+ break;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
@@ -919,7 +922,16 @@ retry:
*/
lock_page(page);
+ /*
+ * Page truncated or invalidated. We can freely skip it
+ * then, even for data integrity operations: the page
+ * has disappeared concurrently, so there could be no
+ * real expectation of this data interity operation
+ * even if there is now a new, dirty page at the same
+ * pagecache address.
+ */
if (unlikely(page->mapping != mapping)) {
+continue_unlock:
unlock_page(page);
continue;
}
@@ -930,18 +942,15 @@ retry:
* end == -1 in that case.
*/
done = 1;
- unlock_page(page);
- continue;
+ goto continue_unlock;
}
if (wbc->sync_mode != WB_SYNC_NONE)
wait_on_page_writeback(page);
if (PageWriteback(page) ||
- !clear_page_dirty_for_io(page)) {
- unlock_page(page);
- continue;
- }
+ !clear_page_dirty_for_io(page))
+ goto continue_unlock;
ret = (*writepage)(page, wbc, data);
if (unlikely(ret)) {
@@ -964,7 +973,8 @@ retry:
}
if (wbc->sync_mode == WB_SYNC_NONE) {
- if (--wbc->nr_to_write <= 0)
+ wbc->nr_to_write--;
+ if (wbc->nr_to_write <= 0)
done = 1;
}
if (wbc->nonblocking && bdi_write_congested(bdi)) {