From 98c4a01c21b99b13d8aaa406ab15b7424ee5ef9f Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 23 May 2018 16:30:49 -0500 Subject: [PATCH] xfsprogs: be careful about what we stat in platform_check_mount 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 just do a really simple sanity check before we try to stat the mountpoint: does its device start with a / ? If not, skip it. Fixes: 4e7a824 ("libxfs/linux.c: Replace use of ustat by stat") Signed-off-by: Eric Sandeen Reviewed-by: Allison Henderson Signed-off-by: Eric Sandeen --- libfrog/linux.c | 10 ++++++++++ 1 file changed, 10 insertions(+) Index: xfsprogs-4.5.0/libxfs/linux.c =================================================================== --- xfsprogs-4.5.0.orig/libxfs/linux.c +++ xfsprogs-4.5.0/libxfs/linux.c @@ -68,7 +68,17 @@ platform_check_ismounted(char *name, cha 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 first, a simple check: does the "dev" start with "/" ? + */ while ((mnt = getmntent(f)) != NULL) { + if (mnt->mnt_fsname[0] != '/') + continue; if (stat64(mnt->mnt_dir, &mst) < 0) continue; if (mst.st_dev != s->st_rdev) @@ -99,7 +109,17 @@ platform_check_iswritable(char *name, ch "mounted filesystem\n"), progname, name); return fatal; } + /* + * 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 first, a simple check: does the "dev" start with "/" ? + */ while ((mnt = getmntent(f)) != NULL) { + if (mnt->mnt_fsname[0] != '/') + continue; if (stat64(mnt->mnt_fsname, &mst) < 0) continue; if ((mst.st_mode & S_IFMT) != S_IFBLK)