From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2130.oracle.com ([156.151.31.86]:36930 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751599AbeAZHNp (ORCPT ); Fri, 26 Jan 2018 02:13:45 -0500 Date: Thu, 25 Jan 2018 23:13:32 -0800 From: "Darrick J. Wong" Subject: Re: [RFC][PATCH] xfs: preserve i_rdev when recycling a reclaimable inode Message-ID: <20180126071332.GB11926@magnolia> References: <1516915298-8886-1-git-send-email-amir73il@gmail.com> <20180125213040.GO9068@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Amir Goldstein Cc: Eryu Guan , Miklos Szeredi , linux-xfs , linux-fsdevel , Christoph Hellwig On Fri, Jan 26, 2018 at 08:51:01AM +0200, Amir Goldstein wrote: > On Thu, Jan 25, 2018 at 11:30 PM, Darrick J. Wong > wrote: > > On Thu, Jan 25, 2018 at 11:21:38PM +0200, Amir Goldstein wrote: > >> Signed-off-by: Amir Goldstein > >> --- > >> > >> Darrick, > >> > >> This patch fixes a problem I am hitting consistenty with xfstest > >> overlay/017 with certain overlay mount options (index=on,nfs_export=off). > >> > >> I see that overlayfs looks up in underlying xfs and gets a chardev > >> or blockdev inode with non initialized i_rdev (these are not whiteout > >> inodes). > >> > >> It takes a certain timing which happens in this test that does lookup > >> immediately after drop caches. The test causes a permanent error in > >> inode cache of xfs that is only fixed after another drop caches or > >> cycle mount. > >> > >> So I am certain there is a problem and that this patch fixes the > >> problem, I'm just not sure this is the right fix and if it is, which > >> is the commit that it "Fixes". > > > > We're basically reinitializing a VFS inode that was on its way to being > > reclaimed, which means that we don't xfs_iread. We still have to > > reinitialize the vfs inode state (because we'd already torn that down), > > so we have to preserve all the vfs inode state that the xfs inode stores > > in the vfs inode. > > > > Oh, right, hch moved if_rdev to i_rdev in 66f364649d870 ("xfs: remove > > if_rdev") but forgot the xfs_reinit_inode usage. so that would be the > > commit that this fixes. Doh. > > > > Then this is a v4.15 regression fix and worth a last minute pull request IMO. > Devices may become unavailable under memory pressure... weird things can happen. It probably ought to have a proper changelog & Fixes: tag then. --D > > > > >> > >> Thanks, > >> Amir. > >> > >> fs/xfs/xfs_icache.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > >> index 3861d61fb265..3ce946063ffe 100644 > >> --- a/fs/xfs/xfs_icache.c > >> +++ b/fs/xfs/xfs_icache.c > >> @@ -295,6 +295,7 @@ xfs_reinit_inode( > >> uint32_t generation = inode->i_generation; > >> uint64_t version = inode->i_version; > >> umode_t mode = inode->i_mode; > >> + dev_t dev = inode->i_rdev; > >> > >> error = inode_init_always(mp->m_super, inode); > >> > >> @@ -302,6 +303,7 @@ xfs_reinit_inode( > >> inode->i_generation = generation; > >> inode->i_version = version; > >> inode->i_mode = mode; > >> + inode->i_rdev = dev; > >> return error; > >> } > >> > >> -- > >> 2.7.4 > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html