Re: 2.6.19 file content corruption on ext3

[Andrei Popa <andrei.popa@i-neo.ro>]

> (On that note: Andrei - if you do test this out, I'd suggest applying my 
> patch too - the one that you already tested. It won't apply cleanly on top 
> of Andrew's patch, but it should be trivial to apply by hand, since you 
> really just want to remove the whole "if (ret) {...}" sequence. I realize 
> that it didn't make any difference for you, but applying that patch is 
> probably a good idea just to remove the noise for a codepath that you 
> already showed to not matter)


I applied Linus patch, Andrew patch, Peter Zijlstra patches(the last
two). All unified patch is attached. I tested and I have no corruption.


diff --git a/fs/buffer.c b/fs/buffer.c
index d1f1b54..263f88e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2834,7 +2834,7 @@ int try_to_free_buffers(struct page *pag
 	int ret = 0;
 
 	BUG_ON(!PageLocked(page));
-	if (PageWriteback(page))
+	if (PageDirty(page) || PageWriteback(page))
 		return 0;
 
 	if (mapping == NULL) {		/* can this still happen? */
@@ -2845,22 +2845,6 @@ int try_to_free_buffers(struct page *pag
 	spin_lock(&mapping->private_lock);
 	ret = drop_buffers(page, &buffers_to_free);
 	spin_unlock(&mapping->private_lock);
-	if (ret) {
-		/*
-		 * If the filesystem writes its buffers by hand (eg ext3)
-		 * then we can have clean buffers against a dirty page.  We
-		 * clean the page here; otherwise later reattachment of buffers
-		 * could encounter a non-uptodate page, which is unresolvable.
-		 * This only applies in the rare case where try_to_free_buffers
-		 * succeeds but the page is not freed.
-		 *
-		 * Also, during truncate, discard_buffer will have marked all
-		 * the page's buffers clean.  We discover that here and clean
-		 * the page also.
-		 */
-		if (test_clear_page_dirty(page))
-			task_io_account_cancelled_write(PAGE_CACHE_SIZE);
-	}
 out:
 	if (buffers_to_free) {
 		struct buffer_head *bh = buffers_to_free;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0f05cab..760442f 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1245,7 +1245,7 @@ retry:
 				wait_on_page_writeback(page);
 
 			if (PageWriteback(page) ||
-					!test_clear_page_dirty(page)) {
+					!test_clear_page_dirty(page, 1)) {
 				unlock_page(page);
 				break;
 			}
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1387749..da2bdb1 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -484,7 +484,7 @@ static int fuse_commit_write(struct file
 		spin_unlock(&fc->lock);
 
 		if (offset == 0 && to == PAGE_CACHE_SIZE) {
-			clear_page_dirty(page);
+			clear_page_dirty(page, 0);
 			SetPageUptodate(page);
 		}
 	}
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index ed2c223..7b87875 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -176,7 +176,7 @@ static int hugetlbfs_commit_write(struct
 
 static void truncate_huge_page(struct page *page)
 {
-	clear_page_dirty(page);
+	clear_page_dirty(page, 1);
 	ClearPageUptodate(page);
 	remove_from_page_cache(page);
 	put_page(page);
diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
index b1a1c72..47a6b62 100644
--- a/fs/jfs/jfs_metapage.c
+++ b/fs/jfs/jfs_metapage.c
@@ -773,7 +773,7 @@ #if MPS_PER_PAGE == 1
 
 	/* Retest mp->count since we may have released page lock */
 	if (test_bit(META_discard, &mp->flag) && !mp->count) {
-		clear_page_dirty(page);
+		clear_page_dirty(page, 1);
 		ClearPageUptodate(page);
 	}
 #else
diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
index 47e7027..a97e198 100644
--- a/fs/reiserfs/stree.c
+++ b/fs/reiserfs/stree.c
@@ -1459,7 +1459,7 @@ static void unmap_buffers(struct page *p
 				bh = next;
 			} while (bh != head);
 			if (PAGE_SIZE == bh->b_size) {
-				clear_page_dirty(page);
+				clear_page_dirty(page, 0);
 			}
 		}
 	}
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index b56eb75..d65ba84 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -343,7 +343,7 @@ xfs_start_page_writeback(
 	ASSERT(!PageWriteback(page));
 	set_page_writeback(page);
 	if (clear_dirty)
-		clear_page_dirty(page);
+		clear_page_dirty(page, 1);
 	unlock_page(page);
 	if (!buffers) {
 		end_page_writeback(page);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 4830a3b..175ab3c 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -253,13 +253,13 @@ #define ClearPageUncached(page)	clear_bi
 
 struct page;	/* forward declaration */
 
-int test_clear_page_dirty(struct page *page);
+int test_clear_page_dirty(struct page *page, int must_clean_ptes);
 int test_clear_page_writeback(struct page *page);
 int test_set_page_writeback(struct page *page);
 
-static inline void clear_page_dirty(struct page *page)
+static inline void clear_page_dirty(struct page *page, int
must_clean_ptes)
 {
-	test_clear_page_dirty(page);
+	test_clear_page_dirty(page, must_clean_ptes);
 }
 
 static inline void set_page_writeback(struct page *page)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 237107c..561d702 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -848,7 +848,7 @@ EXPORT_SYMBOL(set_page_dirty_lock);
  * Clear a page's dirty flag, while caring for dirty memory
accounting. 
  * Returns true if the page was previously dirty.
  */
-int test_clear_page_dirty(struct page *page)
+int test_clear_page_dirty(struct page *page, int must_clean_ptes)
 {
 	struct address_space *mapping = page_mapping(page);
 	unsigned long flags;
@@ -866,7 +866,9 @@ int test_clear_page_dirty(struct page *p
 		 * page is locked, which pins the address_space
 		 */
 		if (mapping_cap_account_dirty(mapping)) {
-			page_mkclean(page);
+			int cleaned = page_mkclean(page);
+			if (!must_clean_ptes && cleaned)
+				set_page_dirty(page);
 			dec_zone_page_state(page, NR_FILE_DIRTY);
 		}
 		return 1;
diff --git a/mm/rmap.c b/mm/rmap.c
index d8a842a..3f9061e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -448,7 +448,7 @@ static int page_mkclean_one(struct page 
 		goto unlock;
 
 	entry = ptep_get_and_clear(mm, address, pte);
-	entry = pte_mkclean(entry);
+	/*entry = pte_mkclean(entry);*/
 	entry = pte_wrprotect(entry);
 	ptep_establish(vma, address, pte, entry);
 	lazy_mmu_prot_update(entry);
diff --git a/mm/truncate.c b/mm/truncate.c
index 9bfb8e8..cafa843 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -70,7 +70,7 @@ truncate_complete_page(struct address_sp
 	if (PagePrivate(page))
 		do_invalidatepage(page, 0);
 
-	if (test_clear_page_dirty(page))
+	if (test_clear_page_dirty(page, 1))
 		task_io_account_cancelled_write(PAGE_CACHE_SIZE);
 	ClearPageUptodate(page);
 	ClearPageMappedToDisk(page);
@@ -386,7 +386,7 @@ int invalidate_inode_pages2_range(struct
 					  PAGE_CACHE_SIZE, 0);
 				}
 			}
-			was_dirty = test_clear_page_dirty(page);
+			was_dirty = test_clear_page_dirty(page, 0);
 			if (!invalidate_complete_page2(mapping, page)) {
 				if (was_dirty)
 					set_page_dirty(page);

> 
> > I'm guessing that if we do the WARN_ON() some folks might get a lot of 
> > output, perhaps WARN_ON_ONCE() ?
> 
> Well, I'd rather get lots of noise to see all the paths that can cause 
> this. We've been concentrating mainly on one (try_to_free_buffers()), but 
> that one was already shown not to matter or at least not to be the _whole_ 
> issue, so..
> 
> 		Linus

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