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SubjectRe: Bugfix in dquot_transfer()

On Sun, 17 Sep 2000, Jan Kara wrote:

> > How about the following:
> > * dquot_{alloc,free}_block() _never_ blocks.
> > * we have 3 inlined helper functions - alloc_block(), free_block() and
> > change_xid(). They get exclusion (BKL, spinlock, whatever) and update both
> > quota and i_blocks.
> >
> > Consequences:
> > * quota for filesystems without ->i_blocks is history. It doesn't
> > work anyway - quota for minixfs is so easy to screw that it's not even
> > funny.
> > * we can't print any messages from the dquot_{alloc,free}_block().
> > Let the helper thread do it - we would just add a request to queue and let
> > it pick the thing.
> > BTW, use of global buffer for creating the messages is
> > extremely bad idea - TTY output can block and you've got no protection
> > around print_warning().

> Seems I'll have to read that part of kernel... I didn't expect writing
> to console can block (especially as this code was there for ages).

Come again? It's current->tty, not console. Can be _any_ TTY driver. And
this code had been racey since conception (Melbourne quota was a major
PITA way before Linux appeared).

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