Initial filesystem design synopsis.

Simon 'corecode' Schubert corecode at fs.ei.tum.de
Mon Feb 26 17:24:53 PST 2007


Matthew Dillon wrote:
    The alternative is to set a specific endianess for the filesystem in
    stone, just like the 'network byte order' concept locked in a 
    particular byte ordering for packets.  People today STILL hate the
    fact that they have to translate certain protocols to network byte
    order even when the machines on both ends use the same byte order,
    but one that happens to not be 'network' byte order.
But is this really so much effort compared to doing this thing only if the endianness differs between storage and native?

I think code would always look something like:

read data
if (need_conversion)
 convert_data
use data
if (need_conversion)
 convert_data_back
write data
how is that different from:

read data
convert_data
use data
convert_data_back
write_data
yes, sure, there is *always* the conversion.  but seriously, that's negligible compared to disk seek/write times.

    We're not making that same mistake, hence the filesystem will be speced
    for endian neutrality even if the code isn't written to support it right
    off the bat.
I don't think having a fixed byte ordering is a mistake.  Actually I fear that converting the byte order only if the orders differ might introduce more or at least more obscure bugs.

cheers
 simon
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