[PATCH] ext2 corruption - regression between 2.6.9 and 2.6.10

Whilst trying to stress test a Promise SX8 card, we stumbled across
some nasty filesystem corruption in ext2. Our tests involved
creating an ext2 partition, mounting, running several concurrent
fsx's over it, umounting, and fsck'ing, all scripted[1]. The fsck
would always return with errors.

This regression was traced back to a change between 2.6.9 and
2.6.10, which moves the functionality of ext2_put_inode into
ext2_clear_inode.  The attached patch reverses this change, and
eliminated the source of corruption.

Mingming Cao <cmm@us.ibm.com> said:

I think his patch for ext2 is correct.  The corruption on ext3 is not the same
issue he saw on ext2.  I believe that's the race between discard reservation
and reservation in-use that we already fixed it in 2.6.12- rc1.

For the problem related to ext2, at the time when we design reservation for
ext3, we decide we only need to discard the reservation at the last file
close, so we have ext3_discard_r...