Messages in this thread | | | Date | Thu, 3 Jan 2002 16:42:46 -0700 | From | Andreas Dilger <> | Subject | Re: losetuping files in tmpfs fails? |
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On Jan 03, 2002 15:10 -0800, Andrew Morton wrote: > Andy Gaynor wrote: > > Whilst trying to figure out why my dang stripes won't persist (a separate > > but worrisome issue), I wrote a dittie which creates a couple junk files in > > /tmp (tmpfs), associates loop devices with them, whoops, losetup craps out. > > > > ... > > /tmp# mount | grep tmp # Filesystem is ... > > tmpfs on /tmp type tmpfs (rw) # tmpfs > > /tmp# echo foo > foo # Create file foo > > /tmp# losetup /dev/loop/5 foo # Give foo to /dev/loop/5 > > ioctl: LOOP_SET_FD: Invalid argument # DISCO!!! <o > <o > > > Yup, tmpfs doesn't provide some of the facilities which the > loop driver requires. Specifically, prepare_write() and > commit_write(). > > Probably it's not too hard to change loop to use generic_file_write(), > and it will then permit tmpfs file-backed loop mounts. > > It's not obvious that there's a burning need to support loop-on-tmpfs > though, is there?
Well, if you are using tmpfs as your /tmp filesystem (presumably not such a strange situation given the name ;-), then any tool which creates a loopback in /tmp will break. Good examples would be mkinitrd, or anything that is generating a floppy image (e.g. Linux Router Project floppy, boot floppy tools, etc).
Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/
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