Re: How do I fsck and XFS file system in "Squeeze"

Mark Allums put forth on 5/22/2010 8:32 PM:
On 5/22/2010 2:22 AM, Stan Hoeppner wrote:
Mark Allums put forth on 5/21/2010 7:37 PM:

64-bit Knoppix is in the TODO list of Klaus Knopper, but for rescue
purposes, 32-bit should be able to do the job.

This is incorrect _if_ the filesystem is large and thus contains 64
bit inode
numbers. If there is any remote possibility that 64 bit inodes exist
on the
XFS filesystem to be checked/repaired, the rescue kernel and xfsprogs
need to
be 64 bit binaries.

That's a very odd thing. Thanks for correcting me. I would not have
guessed that file system structure would be dependent on OS word width.
I mean, that seems like a catastrophic implementation/design bug.

It's not an instruction word width issue, but has more to do with the width of
the data registers, and addressable virtual memory of 32bit platforms.

Running a 32bit kernel, how do you process 64bit inode numbers in 32bit data
registers? That would require a lot of code changes for a dying platform
(ia32). Add the fact that i386 kernels have a maximum virtual address space
of 16TB, which, not coincidentally, is the maximum 32bit XFS filesystem size.
I think this last point is really the key to this issue, because if you were
to add support to 32bit XFS for 9 exabyte filesystems, you'd only be able to
mmap files up to the 16TB boundary. AFAIK, most I/O these days is done with
mmap. If you have files or filesystems larger than your virtual memory space,
you can't mmap anything beyond that address boundary.


To UNSUBSCRIBE, email to debian-user-REQUEST@xxxxxxxxxxxxxxxx
with a subject of "unsubscribe". Trouble? Contact listmaster@xxxxxxxxxxxxxxxx

Relevant Pages

  • [PATCH 1/2] VFS: update overview document
    ... -The Virtual File System (otherwise known as the Virtual Filesystem ... The pathname argument is used by the VFS to search through the ... -directory entry cache (dentry cache or "dcache"). ... -An individual dentry usually has a pointer to an inode. ...
  • Re: [PATCH 0/7] vfs: notify_changes() error handling
    ... there are more problems than these in the truncate path. ... have filesystems call their truncate sequence ... from ->setattr if filesystem specific operations are required. ... to be used to copy simple attributes into the generic inode. ...
  • Re: Starting a grad project that may change kernel VFS. Early research
    ... directory of the filesystem after an unclean shutdown. ... No. Updating the size at the same time as the main inode write is far ... You don't need to sync before umount. ... have a file living in src/linux/v2.6.29/README, and it is a hard link ...
  • Re: [PATCH] prune_icache_sb
    ... In Linux a filesystem is a dumb layer which sits between the VFS and the ... inode (that this cluster lock is created for). ...
  • [RFC][0/21]extend file size and filesystem size
    ... I have tried to extend the filesystem size and file size in ext2/3 ... A summary of my reform to extend the specs in ext2/3 is as below. ... type of variables in relation to block and inode, ... Change the type of 4byte variables manipulating a block or ...