Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754733AbbHDT6Q (ORCPT ); Tue, 4 Aug 2015 15:58:16 -0400 Received: from mga11.intel.com ([192.55.52.93]:20469 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752621AbbHDT6M (ORCPT ); Tue, 4 Aug 2015 15:58:12 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,610,1432623600"; d="scan'208";a="619267249" From: Matthew Wilcox To: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Matthew Wilcox Subject: [PATCH 03/11] dax: Improve comment about truncate race Date: Tue, 4 Aug 2015 15:57:57 -0400 Message-Id: <1438718285-21168-4-git-send-email-matthew.r.wilcox@intel.com> X-Mailer: git-send-email 2.4.6 In-Reply-To: <1438718285-21168-1-git-send-email-matthew.r.wilcox@intel.com> References: <1438718285-21168-1-git-send-email-matthew.r.wilcox@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1248 Lines: 37 From: Matthew Wilcox Jan Kara pointed out I should be more explicit here about the perils of racing against truncate. The comment is mostly the same as for the PTE case. Signed-off-by: Matthew Wilcox --- fs/dax.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 15f8ffc..0a13118 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -553,7 +553,12 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) goto fallback; - /* Guard against a race with truncate */ + /* + * If a truncate happened while we were allocating blocks, we may + * leave blocks allocated to the file that are beyond EOF. We can't + * take i_mutex here, so just leave them hanging; they'll be freed + * when the file is deleted. + */ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; if (pgoff >= size) { result = VM_FAULT_SIGBUS; -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/