Re: [PATCH 1/2] ext3 percpu counter fixes to suppport for morethan 2**31 ext3 free blocks counter

From: Mingming Cao
Date: Mon Apr 24 2006 - 13:49:16 EST


On Fri, 2006-04-21 at 17:56 -0700, Ravikiran G Thirumalai wrote:
> On Fri, Apr 21, 2006 at 07:59:06AM -0700, Mingming Cao wrote:
> > The following patches are to fix the percpu counter issue support more
> > than 2**31 blocks for ext3, i.e. allow the ext3 free block accounting
> > works with more than 8TB storage.
> >
> > [PATCH 1] - Generic perpcu longlong type counter support: global counter
> > type changed from long to long long. The local counter is still remains
> > 32 bit (long type), so we could avoid doing 64 bit update in most cases.
> > Fixed the percpu_counter_read_positive() to handle the 0 value counter
> > correctly;Add support to initialize the global counter to a value that
> > are greater than 2**32.
> >
> > [PATCH 2] - ext3 part of the changes: make use of the new support to
> > initialize the free blocks counter, instead of using percpu_counter_mod
> > () indirectly.
> >
> > Patches against 2.6.17-rc1-mm2. Tested on a freshly created 10TB ext3.
> >
> > Here is Patch 1.
> >
> > Signed-Off-By: Mingming Cao <cmm@xxxxxxxxxx>
> >
> > ...
> > +static inline void
> > +percpu_counter_ll_init(struct percpu_counter *fbc, long long amount)
> > +{
> > + spin_lock_init(&fbc->lock);
> > + fbc->count = amount;
> > + fbc->counters = alloc_percpu(long);
> > +}
> > +
>
> Do we need another interface for this? Why not change percpu_counter_init
> and users to use 'amount' as an additional argument instead?

Suggestion accepted.:-)

Mingming

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