even when the filesystem gets unmounted, this changed data still stick
in the buffers and when you try to make a copy of this isofs now,
ISO9660 file name is corrupt (lower case) and as a result e.g. you can't
read these files anymore in MSDOS.
trashing memory/buffer cache or running "flushb" on the device before
reading the isofs data seems to fix this but I don't think this should
be necessary.
at least after umount, these modified buffers should be flushed IMHO.
otherwise, e.g. mounting a freshly mastered isofs to do some last
minutes checks will trash the data and if you're trying to burn
a CDR afterwards, data will be broken :-(
please try the following:
cd /tmp
mkisofs /usr/src/linux/fs > iso.orig
swapoff /dev/swap2 # (or use any other spare partition...)
cp iso.orig /dev/swap2
mount -t iso9660 /dev/swap2 /mnt
ls -lR /mnt > /dev/null
umount /mnt
dd if=/dev/swap2 bs=`wc -c < iso.orig` count=1 of=iso.copy1
mount -t iso9660 /dev/swap2 /mnt
umount /mnt
dd if=/dev/swap2 bs=`wc -c < iso.orig` count=1 of=iso.copy2
cmp -l iso.orig iso.copy1 | wc
cmp -l iso.orig iso.copy2 | wc
why does `mount -o map=off ...' flush buffers (as iso.copy2 isn't corrupted anymore) ?
instead of using `cmp' for comparison you can also do
cp iso.orig /dev/swap2
mount -o map=off -t iso9660 /dev/swap2 /mnt
ls -l /mnt
umount /mnt
cp iso.copy1 /dev/swap2
mount -o map=off -t iso9660 /dev/swap2 /mnt
ls -l /mnt
umount /mnt
comments ?
Harald
-- All SCSI disks will from now on ___ _____ be required to send an email notice 0--,| /OOOOOOO\ 24 hours prior to complete hardware failure! <_/ / /OOOOOOOOOOO\ \ \/OOOOOOOOOOOOOOO\ \ OOOOOOOOOOOOOOOOO|// Harald Koenig, \/\/\/\/\/\/\/\/\/ Inst.f.Theoret.Astrophysik // / \\ \ koenig@tat.physik.uni-tuebingen.de ^^^^^ ^^^^^