Messages in this thread | | | Subject | Re: BKL removal from VFS | From | Steve Lord <> | Date | 19 Feb 2002 10:19:11 -0600 |
| |
On Tue, 2002-02-19 at 10:11, Alexander Viro wrote: > > > On 19 Feb 2002, Steve Lord wrote: > > > Al, I am not proposing this to go in, but what is your opinion on a > > change like this? XFS does not need the BKL at all, so for some aim7 > > experiments on large systems this patch was used to bypass the BKL for > > filesystems which state they can live without it: > > > +#define lock_kernel_optional(ip) \ > > + if (!(ip->i_flags & S_NOBKL)) lock_kernel() > > + > > Denied. No way in hell that (or similar) will ever go in. Locking must > be consistent, _period_. No provisions for "legacy drivers" and crap > like that - it's a standard policy in all kernel and that had been discussed > a lot of times. > > _Please_, check 2.5. We already don't take BKL on majority of directory > operations. The rest will follow pretty soon. > > In particular, in current Linus' tree there are 3 (three) instances of > lock_kernel() in fs/namei.c. Namely, ->permission() and two calls of > d_move(). The latter will go when ->d_parent mess is cleaned up. The > former will go as soon as we get to ->setattr()/->permission() cleanups - > hopefully in a week or so. > > In general, such changes are done by global lock shifting - simultaneous > for all instances and being a trivial search-and-replace. Once the lock > is taken inside the method individual filesystems/drivers/etc. can > shrink the protected areas - in separate patches. > > That's how it works - and that's how it had been done for most of the methods > already. Magic flags that make locking different for different instances > are Not Good. And not needed - see above for the usual way to do that stuff.
Whoa, light blue touch paper and stand back! Like I said I was not proposing this to go into the kernel, just asking your opinion. Yes I am aware of the changes going into locking in 2.5 and like the way things are going there, XFS is ticking along quite happily in 2.5.5-pre1 here.
Steve
--
Steve Lord voice: +1-651-683-3511 Principal Engineer, Filesystem Software email: lord@sgi.com - 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/
| |