[ENBD] ENBD on 2.4.x

[Jon Arney]

> Are you mounting the fs sync?
No, I'm not, but I'll give it a shot.

> Probably vfs is full. File bigger than memory, etc. Is the fs mounted
> sync? If not, mount it sync. If that doesn't help, load the module with
> sync_intvl=1. That will flush VFS frequently, before it can ever fill
> up (well, small ram, fast cpu will still let it block, but we hope
> not).

When I say "Blocks indefinitely", I mean that it blocks and NEVER
flushes. It's dead, jim! :)

As to the "merge_requests=0" option, I suppose I should have
used that before jumping to conclusions, but you should see
the VAST changes between 2.4.0 and 2.4.1 in the 'elevator.c' code.
It just makes me a little scared that whatever's there isn't stable,
so I'd rather not try to muck with it until it is.  I agree that we
should try to clean up the merge code and I'll try your 
suggestion:

  int nbd = MINOR(bh->b_rdev) >> NBD_SHIFT;
  if (bh->b_size != blksize_size[NBD_MAJOR][nbd])
    NBD_ALERT ...

and see what happens, but I have a sneaking suspicion that we should
wait until like 2.4.5 or something before we believe that the elevator
stuff is stable.

Also, I stand corrected on the 'd[ei]spatch' spelling.

-Jon


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