Re: [PATCH] remove BKL from ext2's readdir

Andrew Morton (akpm@digeo.com)
Sat, 15 Mar 2003 02:36:14 -0800


Alex Tomas <bzzz@tmi.comex.ru> wrote:
>
>
> hi!
>
> I took a look at readdir() in 2.5.64's ext2 and found it serialized by BKL.

Yes, I had this in -mm for ages, seem to have lost it. Also removal of BKL
from lseek().

The theory is that the lock is there to avoid f_pos races against lseek. We
ended up deciding that the way to address this is to ensure that all readdir
implementations do:

foo_readdir()
{
loff_t pos = file->f_pos;

....
<code which doesn't touch file->f_pos, but which modifies pos>
...

file->f_pos = pos;
}

ext2 does this right and does not need the lock_kernel(). Once all
filesystems have been audited (and, if necessary, fixed) we can remove the
BKL from lseek also.

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