From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2130.oracle.com ([141.146.126.79]:57484 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993AbeEBT6Q (ORCPT ); Wed, 2 May 2018 15:58:16 -0400 Date: Wed, 2 May 2018 12:58:09 -0700 From: "Darrick J. Wong" Subject: Re: [PATCH] xfsprogs: be careful about what we stat in platform_check_mount Message-ID: <20180502195809.GZ4127@magnolia> References: <92bcf603-5106-9fa0-1b48-0d13ff0608c8@sandeen.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <92bcf603-5106-9fa0-1b48-0d13ff0608c8@sandeen.net> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: linux-xfs On Wed, May 02, 2018 at 02:56:22PM -0500, Eric Sandeen wrote: > After we lost ustat(2) in commit 4e7a824, we ended up with a slightly > bonkers method to determine if our target block device was mounted: > it goes through every entry returned by getmntent and stats the dir > to see if its underlying device matches ours. > > Unfortunately that dir might be a hung nfs server and sadness ensues. > > So do some pre-checks; can we stat the mounted "device?" If so is > it really a block device? If not, skip it. > > Fixes: 4e7a824 ("libxfs/linux.c: Replace use of ustat by stat") > Signed-off-by: Eric Sandeen Looks ok, Reviewed-by: Darrick J. Wong --D > --- > > diff --git a/libxfs/linux.c b/libxfs/linux.c > index 0bace3e..7350fa7 100644 > --- a/libxfs/linux.c > +++ b/libxfs/linux.c > @@ -77,7 +77,21 @@ platform_check_mount(char *name, char *block, struct stat *s, int flags) > progname, name); > return 1; > } > + /* > + * This whole business is to work out if our block device is mounted > + * after we lost ustat(2), see: > + * 4e7a824 libxfs/linux.c: Replace use of ustat by stat > + * We don't really want to stat every single mounted directory, > + * as that may include tmpfs, cgroups, procfs or - worst - hung nfs > + * servers. So we check the "device" before going after the mountpoint. > + */ > while ((mnt = getmntent(f)) != NULL) { > + /* If the "fsname" is't a stat-able device, skip it */ > + if (stat(mnt->mnt_fsname, &mst) < 0) > + continue; > + if (!S_ISBLK(mst.st_mode)) > + continue; > + /* Ok, this entry does seem to be a mounted block device */ > if (stat(mnt->mnt_dir, &mst) < 0) > continue; > if (mst.st_dev != s->st_rdev) > > -- > 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