GNU bug report logs - #21372
df prioritizes some bind mounts over real ones.

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Message #49 received at 21372 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Dave Chiluk <chiluk <at> canonical.com>, 21372 <at> debbugs.gnu.org
Subject: Re: bug#21372: [PATCH v4] df: fix prioritize real mounts over bind
 mounts
Date: Tue, 22 Sep 2015 01:43:33 +0100

[Message part 1 (text/plain, inline)]

On 21/09/15 23:44, Pádraig Brady wrote:
> On 21/09/15 21:04, Dave Chiluk wrote:
>> Fixes an issue where bind mounts with shorter mount directories than the
>> original mount are prioritized when running df.  The root cause of this
>> is that /proc/self/mountinfo now lists the filesystem device with bind
>> mounts rather than the source directory. With /etc/mtab the source
>> device was listed as the originating directory so this was not an issue.
>>
>> More information is available here.
>> https://bugs.launchpad.net/ubuntu/+source/coreutils/+bug/1432871
>> ---
>>  src/df.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/df.c b/src/df.c
>> index 2e541b9..4a3afa2 100644
>> --- a/src/df.c
>> +++ b/src/df.c
>> @@ -652,9 +652,14 @@ filter_mount_list (bool devices_only)
>>                else if ((strchr (me->me_devname, '/')
>>                         /* let "real" devices with '/' in the name win.  */
>>                          && ! strchr (devlist->me->me_devname, '/'))
>> -                       /* let a shorter mountdir win.  */
>> -                       || (strlen (devlist->me->me_mountdir)
>> +                       /* let a shorter mountdir win. If it's mntroot is */
>> +                       /* also shorter. i.e. not a bind mount. */
>> +                       || ((strlen (devlist->me->me_mountdir)
>>                             > strlen (me->me_mountdir))
>> +                          && (devlist->me->me_mntroot == NULL
>> +                             || me->me_mntroot == NULL
>> +                             || (strlen (devlist->me->me_mntroot)
>> +                                 >= strlen(me->me_mntroot))))
>>                         /* let an entry overmounted on a new device win...  */
>>                         || (! STREQ (devlist->me->me_devname, me->me_devname)
>>                             /* ... but only when matching an existing mnt point,
>>
> 
> This logic looks correct thanks.
> I'll adjust the comment a bit and maybe refactor
> all the conditions to a single nearer_device_root boolean.
> 
> I'll push this later on,
> with the associated gnulib update.

Attached is the refactored patch,
with also lots of adjustments to commit messages.
I'll apply tomorrow.

thanks,
Pádraig.

[df-elide-bind-mounts.patch (text/x-patch, attachment)]

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