Messages in this thread | | | Date | Wed, 29 Mar 2006 17:54:46 -0800 | From | Andrew Morton <> | Subject | Re: [RFC][PATCH 0/2]Extend ext3 filesystem limit from 8TB to 16TB |
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Mingming Cao <cmm@us.ibm.com> wrote: > > The things need to be done to complete this work is the issue with > current percpu counter, which could not handle u32 type count well.
I'm surprised there's much of a problem here. It is a 32-bit value, so it should mainly be a matter of treating the return value from percpu_counter_read() as unsigned long.
However a stickier problem is when dealing with a filesystem which has, say, 0xffff_ff00 blocks. Because percpu counters are approximate, and a counter which really has a value of 0xffff_feee might return 0x00000123. What do we do then?
Of course the simple option is to nuke the percpu counters in ext3 and use atomic_long_t (which is signed, so appropriate treat-it-as-unsigned code would be needed). I doubt if the percpu counters in ext3 are gaining us much. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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