DragonFly BSD
DragonFly kernel List (threaded) for 2006-01
[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]

Re: nullfs stabilization I

From: "Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>
Date: Tue, 10 Jan 2006 21:05:15 +0100

Matthew Dillon wrote:
    (2) Do not have a shadow callback.  Instead have null_nresolve()
	call a new function, cache_shadow(), which creates the relationship
	between the upper and lower layer namecache records.  Only
	null_nresolve() would need the added sophistication.

While I completely agree with the rest of your proposals, I see one problem here:

Imagine you create a file in the NULLFS layer. For this the code cache_lookup()s and then gets a locked namecache entry, which might not be resolved yet (new file, not in cache). This would mean that we have a locked record but no shadow association. At the same time another process can race in the shadowed layer and as well lock the record which is the counterpart to the already locked NULLFS namecache entry.

Not good. This is the reason why I used this callback in the first place. Do you have a better method to do this?


Serve - BSD     +++  RENT this banner advert  +++    ASCII Ribbon   /"\
Work - Mac      +++  space for low €€€ NOW!1  +++      Campaign     \ /
Party Enjoy Relax   |   http://dragonflybsd.org      Against  HTML   \
Dude 2c 2 the max   !   http://golden-apple.biz       Mail + News   / \

[Date Prev][Date Next]  [Thread Prev][Thread Next]  [Date Index][Thread Index]