df reports bind mounts creating noisy output

[Bob Proulx]

In order to develop and compile for a number of different GNU/Linux
system configurations it is typical to use a chroot build system
utilizing Linux kernel bind mounts.  Also this allows running 32-bit
applications in a particular configuration on a 64-bit system.

However on these systems running 'df' produces long and redundant
output.  This has been annoying me.  Here is 'df -T' output.

  Filesystem    Type   1K-blocks      Used Available Use% Mounted on
  /dev/sda1 reiserfs   115230652 106305108   8925544  93% /
  tmpfs        tmpfs      511324         0    511324   0% /dev/shm
  /dev/hda5      xfs    18584960    477332  18107628   3% /chroots/oldtesuji
  /home         none   115230652 106305108   8925544  93% /chroots/rh9/home
  /tmp          none   115230652 106305108   8925544  93% /chroots/rh9/tmp
  /home         none   115230652 106305108   8925544  93% /chroots/rh7.3/home
  /tmp          none   115230652 106305108   8925544  93% /chroots/rh7.3/tmp
  /home         none   115230652 106305108   8925544  93% /chroots/sid64/home
  /tmp          none   115230652 106305108   8925544  93% /chroots/sid64/tmp
  /home         none   115230652 106305108   8925544  93% /chroots/sid32/home
  /tmp          none   115230652 106305108   8925544  93% /chroots/sid32/tmp
  /home         none   115230652 106305108   8925544  93% /chroots/woody/home
  /tmp          none   115230652 106305108   8925544  93% /chroots/woody/tmp
  tmpfs        tmpfs       10240       748      9492   8% /dev

That is very noisy.  I propose that bind mounts of type "none" be
ignored by df when listing filesystem information.  The information
only needs to be reported once.  Here is this example with that change.

  Filesystem           1K-blocks      Used Available Use% Mounted on
  /dev/sda1            115230652 106310032   8920620  93% /
  tmpfs                   511324         0    511324   0% /dev/shm
  /dev/hda5             18584960    477332  18107628   3% /chroots/oldtesuji
  tmpfs                    10240       748      9492   8% /dev

Here is a proposed patch to implement this behavior.

2005-10-01  Bob Proulx  <address@hidden>

        * (ME_DUMMY): Add "none" to the list of ignored fs_type
          strings.  Avoids listing bind mounts multiple times.

Index: mountlist.c
===================================================================
RCS file: /home/bob/src/coreutils-cvsroot/coreutils/lib/mountlist.c,v
retrieving revision 1.55
diff -u -r1.55 mountlist.c
--- mountlist.c 22 Sep 2005 06:05:39 -0000      1.55
+++ mountlist.c 1 Oct 2005 15:40:48 -0000
@@ -144,6 +144,7 @@
 # define ME_DUMMY(Fs_name, Fs_type)            \
     (strcmp (Fs_type, "autofs") == 0           \
      || strcmp (Fs_type, "subfs") == 0         \
+     || strcmp (Fs_type, "none") == 0          \
      /* for Irix 6.5 */                                \
      || strcmp (Fs_type, "ignore") == 0)
 #endif