Re: ext4: fix metadata checksum calculation for the superblock

["George Spelvin" <linux@horizon.com>]

> Oh, so ... it's just nfsd that causes the linear fallback?  Regular (i.e.
> non-nfs) users can see everything in the dir, no error messages?

Yup.  After it survived one e2fsck -D, I poked at the directory a bit
to see if I could cause the error.  No success from local access.

It's also probably an NFSv2 client.  I wonder if it's doing something
odd with directory seeks that's causing problems; perhaps htree and the
32-bit seek cookie limit are not friends?

>> I haven't observed it, no.  But the nature of the symptoms suggests it
>> might be happening.

> Hum.  When linear scan happens on a hashed dir, it's scanning the same
> blocks that the hash scan sees.   The htree block looks like a regular
> directory block with one huge "unused" dirent that wraps all the htree
> data.  So, the linear scan should find the exact same files as a htree
> scan would.  If it doesn't, something's wrong.  But you say it isn't,
> so I imagine it's fine.

Maybe I was wrong.  I was worried that it was aborting the directory
scan due to the error and thus files would disappear.  If that doesn't
happen, no worries.