On Friday 12 December 2008 01:56, OGAWA Hirofumi wrote:
> ...Just FYI for people, probably you know though,
> inode->i_size has race on 32bit arch. It is 64bit value, so,
>
> *size += blocksize;
>
> means something like the following. E.g.
>
> load 0x0(size), %reg1
> load 0x4(size), %reg2
> add blocksize, %reg1
> add-carry %reg2
> store %reg1, 0x0(size)
> <---- (W)
> store %reg2, 0x4(size)
>
> So, block I/O library like block_write_full_page() can read the size at
> (W) point. The result may be bogus size.
>
> We have to fix this later, maybe change with phtree. (don't read i_size
> without lock, or use i_size_read()/i_size_write())
Ah, I thought about that when you mentioned it earlier and forgot to
take care of it in my patch. Something like this:
loff_t tux_create_entry(struct inode *dir, const char *name, int len, inum_t
inum, unsigned mode)
{
loff_t size = i_size_read(dir);
int err = _tux_create_entry(dir, name, len, inum, mode, &size);
i_size_write(dir, size);
return err;
}
Regards,
Daniel
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