> From: Dan Magenheimer > Subject: RE: [PATCH V3 0/8] Cleancache: overview > > > From: Christoph Hellwig [mailto:hch@xxxxxxxxxxxxx] > > Subject: Re: [PATCH V3 0/8] Cleancache: overview > > > > On Fri, Jul 23, 2010 at 06:58:03AM -0700, Dan Magenheimer wrote: > > > CHRISTOPH AND ANDREW, if you disagree and your concerns have > > > not been resolved, please speak up. > > Hi Christoph -- > > Thanks very much for the quick (instantaneous?) reply! > > > Anything that need modification of a normal non-shared fs is utterly > > broken and you'll get a clear NAK, so the propsal before is a good > > one. > > Unless/until all filesystems are 100% built on top of VFS, > I have to disagree. Abstractions (e.g. VFS) are never perfect. After thinking about this some more, I can see a way to enforce "opt-in" in the cleancache backend without any changes to non-generic fs code. I think it's a horrible hack and we can try it, but I expect fs maintainers would prefer the explicit one-line-patch opt-in. 1) Cleancache backend maintains a list of "known working" filesystems (those that have been tested). 2) Nitin's proposed changes pass the *sb as a parameter. The string name of the filesystem type is available via sb->s_type->name. This can be compared against the "known working" list. Using the sb pointer as a "handle" requires an extra table search on every cleancache get/put/flush, and fs/super.c changes are required for fs unmount notification anyway (e.g. to call cleancache_flush_fs) so I'd prefer to keep the cleancache_poolid addition to the sb. I'll assume this is OK since this is in generic fs code. Dan -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
