On Tue, 2010-04-27 at 08:00 -0400, Trond Myklebust wrote: > On Tue, 2010-04-27 at 14:35 +1000, Neil Brown wrote: > > Hi Trond, > > I think the above mentioned commit might have added a new race to replace > > the old .... > > > > I have report of a BUG in nfs_page_async_flush. > > > > It isn't a vanilla upstream kernel - there are a bunch of SUSE patches > > in there - so quoting the line-number won't help you, but it is the > > BUG_ON(ret != 0); > > after the call to nfs_set_page_writeback. > > (https://bugzilla.novell.com/show_bug.cgi?id=599628) > > > > This implies that nfs_find_and_lock_request got a new lock on the page, > > and then we found that it was already flagged for writeback. > > That's odd. Callers such as write_cache_pages() should normally be doing > a wait_on_page_writeback() after taking the page lock but prior to > calling the filesystem. The following patch ought to fix it. I suspect the same race exists in the ->readpage() path, so it makes sense to fix nfs_wb_page() rather than putting the wait_on_page_writeback call in nfs_try_to_update_request(). Cheers Trond ------------------------------------------------------------------------------------------------ NFS: Ensure that nfs_wb_page() waits for Pg_writeback to clear From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> Neil Brown reports that he is seeing the BUG_ON(ret == 0) trigger in nfs_page_async_flush. Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> --- fs/nfs/write.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/fs/nfs/write.c b/fs/nfs/write.c index ccde2ae..c700698 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1472,6 +1472,7 @@ int nfs_wb_page_cancel(struct inode *inode, struct page *page) BUG_ON(!PageLocked(page)); for (;;) { + wait_on_page_writeback(page); req = nfs_page_find_request(page); if (req == NULL) break; @@ -1511,10 +1512,12 @@ int nfs_wb_page(struct inode *inode, struct page *page) int ret; while(PagePrivate(page)) { + wait_on_page_writeback(page); if (clear_page_dirty_for_io(page)) { ret = nfs_writepage_locked(page, &wbc); if (ret < 0) goto out_error; + continue; } req = nfs_find_and_lock_request(page); if (!req) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
