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List:       coreutils-bug
Subject:    bug#10863: closed (Re: bug#10863: A possible du bug?)
From:       "Voelker, Bernhard" <bernhard.voelker () siemens-enterprise ! com>
Date:       2012-02-22 7:21:04
Message-ID: 7856072A9D04C24B82DFE2B1112FE38A0F0AD4AC03 () MCHP058A ! global-ad ! net
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George R Goffe wrote:
> This tactic would fail if there was no partition mounted but the specific
> mount point was the culprit like when a user gets root (not uncommon in
> the environments I work in) and goofs by copying data to a mount point but
> has NOT mounted a partition first.

There's no way to find such shadowed files. The kernel hides those files
as long as the filesystem is mounted - unless your process still has
the mount point as working directory. The following snippet demonstrates
that by mounting a filesystem with $(pwd) as mountpoint:

linux:/mnt # mkdir d && cd d

linux:/mnt/d # dd if=/dev/zero of=shadowed bs=1M count=20
20+0 records in
20+0 records out
20971520 bytes (21 MB) copied, 3.34181 s, 6.3 MB/s

linux:/mnt/d # dd if=/dev/zero of=../fs.img bs=1M count=20
20+0 records in
20+0 records out
20971520 bytes (21 MB) copied, 0.495561 s, 42.3 MB/s

linux:/mnt/d # mkfs.ext2 -F ../fs.img >/dev/null 2>&1

linux:/mnt/d # mount -o loop -t ext2 ../fs.img $(pwd)

linux:/mnt/d # ls
shadowed

linux:/mnt/d # find . -size +10000000c -ls
151725 20480 -rw-r--r--   1 root     root     20971520 Feb 14 13:09 ./shadowed

linux:/mnt/d # cd /mnt/d

linux:/mnt/d # ls
lost+found

linux:/mnt/d # find . -size +10000000c -ls

linux:/mnt/d # cd ..

linux:/mnt # umount d

linux:/mnt # find . -size +10000000c -ls
151725 20480 -rw-r--r--   1 root     root     20971520 Feb 14 13:09 ./d/shadowed
 73888 20480 -rw-r--r--   1 root     root     20971520 Feb 14 13:13 ./fs.img

Have a nice day,
Berny


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