do_div considered harmful

From: Andries.Brouwer@cwi.nl
Date: Sun Aug 03 2003 - 21:03:53 EST


Writing this ide capacity patch an hour ago or so
I split off a helper sectors_to_MB() since Erik's recent
patch uses this also.
Now that I compare, he wrote
        nativeMb = do_div(nativeMb, 1000000);
to divide nativeMb by 1000000.
Similarly, I find in fs/cifs/inode.c
        inode->i_blocks = do_div(findData.NumOfBytes, inode->i_blksize);

So, it seems natural to expect that do_div() gives the quotient.
But it gives the remainder.
(Strange, Erik showed correct output.)

Since the semantics of this object are very unlike that of a C function,
I wonder whether we should write DO_DIV instead, or DO_DIV_AND_REM
to show that a remainder is returned.

Andries
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