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From: Jan Kara on 11 Feb 2010 18:10
Make some paranoic checks to verify that code does what it's expected to do.

Signed-off-by: Jan Kara <jack(a)suse.cz>
---
mm/page-writeback.c | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index f37cbc2..a389feb 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -822,6 +822,45 @@ void tag_pages_for_writeback(struct address_space *mapping,
spin_lock_irq(&mapping->tree_lock);
radix_tree_gang_tag_if_tagged(&mapping->page_tree, start, end,
PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE);
+ /* Debugging aid */
+ {
+ int i;
+ pgoff_t index;
+ unsigned int nr_pages;
+ struct pagevec pvec;
+
+ index = start;
+ do {
+ nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+ PAGECACHE_TAG_DIRTY,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+ for (i = 0; i < nr_pages; i++) {
+ if (pvec.pages[i]->index > end) {
+ nr_pages = 0;
+ break;
+ }
+ if (!radix_tree_tag_get(&mapping->page_tree, pvec.pages[i]->index, PAGECACHE_TAG_TOWRITE))
+ printk("Seeing DIRTY !TOWRITE page %lu, state %lu\n", pvec.pages[i]->index, pvec.pages[i]->flags);
+ }
+ pagevec_release(&pvec);
+ } while (nr_pages);
+
+ index = start;
+ do {
+ nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+ PAGECACHE_TAG_TOWRITE,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
+ for (i = 0; i < nr_pages; i++) {
+ if (pvec.pages[i]->index > end) {
+ nr_pages = 0;
+ break;
+ }
+ if (!radix_tree_tag_get(&mapping->page_tree, pvec.pages[i]->index, PAGECACHE_TAG_DIRTY))
+ printk("Seeing !DIRTY TOWRITE page %lu, state %lu\n", pvec.pages[i]->index, pvec.pages[i]->flags);
+ }
+ pagevec_release(&pvec);
+ } while (nr_pages);
+ }
spin_unlock_irq(&mapping->tree_lock);
}
EXPORT_SYMBOL(tag_pages_for_writeback);
--
1.6.4.2

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