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authorNick Piggin <npiggin@suse.de>2007-07-17 04:03:34 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:02 -0700
commit787d2214c19bcc9b6ac48af0ce098277a801eded (patch)
treea040604fdf9620a66dc83a0cde4f2140e2ec25b3 /mm/page-writeback.c
parenta1ed3dda0ad181532f1e0f0d548067fb9fdddac4 (diff)
fs: introduce some page/buffer invariants
It is a bug to set a page dirty if it is not uptodate unless it has buffers. If the page has buffers, then the page may be dirty (some buffers dirty) but not uptodate (some buffers not uptodate). The exception to this rule is if the set_page_dirty caller is racing with truncate or invalidate. A buffer can not be set dirty if it is not uptodate. If either of these situations occurs, it indicates there could be some data loss problem. Some of these warnings could be a harmless one where the page or buffer is set uptodate immediately after it is dirtied, however we should fix those up, and enforce this ordering. Bring the order of operations for truncate into line with those of invalidate. This will prevent a page from being able to go !uptodate while we're holding the tree_lock, which is probably a good thing anyway. Signed-off-by: Nick Piggin <npiggin@suse.de> 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.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ea9da3bed3e..886ea0d5a13 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -824,6 +824,7 @@ int __set_page_dirty_nobuffers(struct page *page)
mapping2 = page_mapping(page);
if (mapping2) { /* Race with truncate? */
BUG_ON(mapping2 != mapping);
+ WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
if (mapping_cap_account_dirty(mapping)) {
__inc_zone_page_state(page, NR_FILE_DIRTY);
task_io_account_write(PAGE_CACHE_SIZE);