On Tue, 2010-04-27 at 18:21 -0400, Trond Myklebust wrote: > 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(). Actually, this patch is even better since it cleans up nfs_wb_page() too. 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. According to the trace in https://bugzilla.novell.com/show_bug.cgi?id=599628 the problem appears to be due to nfs_wb_page() not waiting for the PG_writeback flag to clear. There is a ditto problem in nfs_wb_page_cancel() Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> --- fs/nfs/write.c | 19 ++++--------------- 1 files changed, 4 insertions(+), 15 deletions(-) diff --git a/fs/nfs/write.c b/fs/nfs/write.c index ccde2ae..3aea3ca 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; @@ -1506,30 +1507,18 @@ int nfs_wb_page(struct inode *inode, struct page *page) .range_start = range_start, .range_end = range_end, }; - struct nfs_page *req; - int need_commit; 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; } - req = nfs_find_and_lock_request(page); - if (!req) - break; - if (IS_ERR(req)) { - ret = PTR_ERR(req); + ret = sync_inode(inode, &wbc); + if (ret < 0) goto out_error; - } - need_commit = test_bit(PG_CLEAN, &req->wb_flags); - nfs_clear_page_tag_locked(req); - if (need_commit) { - ret = nfs_commit_inode(inode, FLUSH_SYNC); - if (ret < 0) - goto out_error; - } } return 0; out_error: -- 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
