On Wed, Jun 25, 2008 at 02:40:39PM +0200, Miklos Szeredi (miklos@xxxxxxxxxx) wrote: > From: Miklos Szeredi <mszeredi@xxxxxxx> > > Clearing the uptodate page flag will cause page_cache_pipe_buf_confirm() > to return -ENODATA if that page was in the buffer. This in turn will cause > splice() to return a short or zero count. > > This manifested itself in rare I/O errors seen on nfs exported fuse > filesystems. This is because nfsd uses splice_direct_to_actor() to > read files, and fuse uses invalidate_inode_pages2() to invalidate > stale data on open. > > Fix this by not clearing PG_uptodate on page invalidation. This will > result in the old, invalid page contents being copied. But that's OK, > the contents were valid at splice-in time (which is when the the > "copy" was conceptually done). > > I haven't done an audit of all code that checks the PG_uptodate flags, > but I suspect, that this change won't have any harmful effects. Most > code checks page->mapping to see if the page was truncated or > invalidated, before using it, and retries the find/read on the page if > it wasn't. The page_cache_pipe_buf_confirm() code is an exception in > this regard. What about writing path, when page is written after some previous write? Like __block_prepare_write()? > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx> > --- > mm/truncate.c | 1 - > 1 file changed, 1 deletion(-) > > Index: linux-2.6/mm/truncate.c > =================================================================== > --- linux-2.6.orig/mm/truncate.c 2008-06-24 20:49:25.000000000 +0200 > +++ linux-2.6/mm/truncate.c 2008-06-24 23:28:32.000000000 +0200 > @@ -356,7 +356,6 @@ invalidate_complete_page2(struct address > BUG_ON(PagePrivate(page)); > __remove_from_page_cache(page); > write_unlock_irq(&mapping->tree_lock); > - ClearPageUptodate(page); > page_cache_release(page); /* pagecache ref */ > return 1; > failed: Don't do that, add new function instead which will do exactly that, if you do need exactly this behaviour. Also why isn't invalidate_complete_page() enough, if you want to have that page to be half invalidated? -- Evgeniy Polyakov -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
