From dc1c0523a61932fb0c26a795b7e7391eadf2171a Mon Sep 17 00:00:00 2001

From: Boris Ranto <branto@redhat.com>

Date: Mon, 1 Dec 2014 09:24:14 +0100

Subject: [PATCH 1/1] du: handle sub-bind-mount cycles gracefully

This patch fixes the handling of sub-bind-mount cycles which are

incorrectly detected as the file system errors.  If you bind mount the

directory 'a' to its subdirectory 'a/b/c' and then run 'du a/b' you

will get the circular dependency warning even though nothing is wrong

with the file system.  This happens because the first directory that is

traversed twice in this case is not a bind mount but a child of bind

mount.  The solution is to traverse all the directories in the cycle

that fts detected and check whether they are not a (bind) mount.

* src/du.c (mount_point_in_fts_cycle): New function that checks whether

any of the directories in the cycle that fts detected is a mount point.

* src/du.c (process_file): Update the function to use the new function

that looks up all the directories in the fts cycle instead of only the

last one.

* tests/du/bind-mount-dir-cycle-v2.sh: New test case that exhibits the

described behavior.

* tests/local.mk: Reference the new root test.

---

 src/du.c                            |   23 ++++++++++++++++++++-

 tests/du/bind-mount-dir-cycle-v2.sh |   38 +++++++++++++++++++++++++++++++++++

 tests/local.mk                      |    1 +

 3 files changed, 61 insertions(+), 1 deletions(-)

 create mode 100755 tests/du/bind-mount-dir-cycle-v2.sh

diff --git a/src/du.c b/src/du.c

index ba20120..f5726c7 100644

--- a/src/du.c

+++ b/src/du.c

@@ -419,6 +419,27 @@ print_size (const struct duinfo *pdui, const char *string)

   fflush (stdout);

 }

+/* This function checks whether any of the directories in the cycle that

+   fts detected is a mount point.  */

+

+static bool

+mount_point_in_fts_cycle (FTSENT const *ent)

+{

+  FTSENT const *cycle_ent = ent->fts_cycle;

+

+  while (ent && ent != cycle_ent)

+    {

+      if (di_set_lookup (di_mnt, ent->fts_statp->st_dev,

+                         ent->fts_statp->st_ino) > 0)

+        {

+          return true;

+        }

+      ent = ent->fts_parent;

+    }

+

+  return false;

+}

+

 /* This function is called once for every file system object that fts

    encounters.  fts does a depth-first traversal.  This function knows

    that and accumulates per-directory totals based on changes in

@@ -514,15 +514,11 @@ process_file (FTS *fts, FTSENT *ent)

           break;

         case FTS_DC:

-          if (cycle_warning_required (fts, ent))

+          /* If not following symlinks and not a (bind) mount point.  */

+          if (cycle_warning_required (fts, ent)

+              && ! mount_point_in_fts_cycle (ent))

             {

-              /* If this is a mount point, then diagnose it and avoid

-                 the cycle.  */

-              if (di_set_lookup (di_mnt, sb->st_dev, sb->st_ino))

-                error (0, 0, _("mount point %s already traversed"),

-                       quote (file));

-              else

-                emit_cycle_warning (file);

+              emit_cycle_warning (file);

               return false;

             }

           return true;

diff --git a/tests/du/bind-mount-dir-cycle-v2.sh b/tests/du/bind-mount-dir-cycle-v2.sh

new file mode 100755

index 0000000..08bfae2

--- /dev/null

+++ b/tests/du/bind-mount-dir-cycle-v2.sh

@@ -0,0 +1,38 @@

+#!/bin/sh

+# Check that du can handle sub-bind-mounts cycles as well.

+

+# Copyright (C) 2014 Free Software foundation, Inc.

+

+# This program is free software: you can redistribute it and/or modify

+# it under the terms of the GNU General Public License as published by

+# the Free Software Foundation, either version 3 of the License, or

+# (at your option) any later version.

+

+# This program is distributed in the hope that it will be useful,

+# but WITHOUT ANY WARRANTY; without even the implied warranty of

+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

+# GNU General Public License for more details.

+

+# You should have received a copy of the GNU General Public License

+# along with this program.  If not, see <http://www.gnu.org/licenses/>.

+

+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src

+print_ver_ du

+require_root_

+

+cleanup_() { umount a/b/c; }

+

+mkdir -p a/b/c || framework_failure_

+mount --bind a a/b/c \

+  || skip_ 'This test requires mount with a working --bind option.'

+

+echo a/b/c > exp || framework_failure_

+echo a/b >> exp || framework_failure_

+

+du a/b > out 2> err || fail=1

+sed 's/^[0-9][0-9]*	//' out > k && mv k out

+

+compare /dev/null err || fail=1

+compare exp out || fail=1

+

+Exit $fail

diff --git a/tests/local.mk b/tests/local.mk

index 653c984..349e322 100644

--- a/tests/local.mk

+++ b/tests/local.mk

@@ -117,6 +117,7 @@ all_root_tests =				\

   tests/dd/skip-seek-past-dev.sh		\

   tests/df/problematic-chars.sh			\

   tests/du/bind-mount-dir-cycle.sh		\

+  tests/du/bind-mount-dir-cycle-v2.sh		\

   tests/id/setgid.sh				\

   tests/install/install-C-root.sh		\

   tests/ls/capability.sh			\

-- 

1.7.2.5

diff -urNp coreutils-8.22-orig/tests/du/bind-mount-dir-cycle.sh coreutils-8.22/tests/du/bind-mount-dir-cycle.sh

--- coreutils-8.22-orig/tests/du/bind-mount-dir-cycle.sh	2013-12-04 15:48:30.000000000 +0100

+++ coreutils-8.22/tests/du/bind-mount-dir-cycle.sh	2015-07-02 15:58:49.230632316 +0200

@@ -27,12 +27,11 @@ mount --bind a a/b \

   || skip_ "This test requires mount with a working --bind option."

 echo a > exp || framework_failure_

-echo "du: mount point 'a/b' already traversed" > exp-err || framework_failure_

-du a > out 2> err && fail=1

+du a > out 2> err || fail=1

 sed 's/^[0-9][0-9]*	//' out > k && mv k out

-compare exp-err err || fail=1

+compare /dev/null err || fail=1

 compare exp out || fail=1

 Exit $fail