On Wed, May 13, 2009 at 02:05:16PM -0700, p v wrote:
> doesn't seem to work - I tried to clear the extflg in the
> versionnum of the superblock (in every copy of it as well) but it
> doesn't work. The flag is still set on all extents.
Sure - that xfs_db command only clears it from the superblock so
that *new* preallocations don't have the unwritten bit set. it
doesn't change existing allocations.
> And once I make the file xfs_repair complains and resets the sb
> flag - my guess is that in the extent allocation path it is
> hardcoded for the version 4.
More likely is that repair is seeing an existing unwritten extent
and setting the flag on the superblock.
> - any extent allocated beyond file size will get the flag .
Allocation beyond EOF does not use unwritten extents unless
it is preallocation.
> Also - 2 questions -
> 1) what is inode64 and where can I find out all of the
> undocumented mkfs/mount options (it's unfortunate that such a good
> fs doesnt' have a correspondingly good documentation)
All the options should be documented. Try 'man mkfs.xfs', 'man 8
mount' and Documentation/filesystems/xfs.txt
> 2) why is the largest extent size limited to xxx blocks
2^21 blocks. Limited to that because there are 21 bits for
the extent size in the on disk extent record.
> (can't find
> out thenumber - when does the inode get finally flushed? ls -i
> reports 19 as the inode number but even after unmounting inode 19
> in xfs_db still shows a free inode - is it still only in the
Might be, or you are seeing stale cached block device data
(xfs_db operates in a different address space to a mounted
filesystem). Try dropping the page cache and then re-read.
> ? I assumed that xfs_bmap gets me the correct number of
> extents but now looking at the inode with xfs_db it's obvious that
> xfs_bmap reports contiguous ranges rather than actual extents in
> the blockmap tree.
Sure it does. You can tell how many extents a specific range is from
their maximum size (e.g. one extent per 8GB for a 4k block size