On Thu, Mar 15 2007, Nick Piggin wrote: > On Thu, Mar 15, 2007 at 12:52:37PM +0100, Jens Axboe wrote: > > On Wed, Mar 14 2007, Nick Piggin wrote: > > > Here are a couple of splice patches I found when digging in the area. > > > I could be wrong, so I'd appreciate confirmation. > > > > > > Untested other than compile, because I don't have a good splice test > > > setup. > > > > > > Considering these are data corruption / information leak issues, then > > > we could do worse than to merge them in 2.6.21 and earlier stable > > > trees. > > > > > > Does anyone really use splice stealing? > > > > That's a damn shame, I'd greatly prefer if we can try and fix it > > instead. Splice isn't really all that used yet to my knowledge, but > > stealing is one of the niftier features I think. Otherwise you're just > > copying data again. > > We should be able to allow for it with the new a_ops API I'm working > on.
"Should be" and in progress stuff, is it guarenteed to get there? > Basically we can pass the page down to the filesystem, and tell it to > attempt to install that page in-place. > > The problem is that we can't just put this page here hoping the fs can > take it, becaue it might fail allocating blocks, for example. > > Anyway, we can still copy files with 1 less copy than read/write ;) It's not about 1 vs 2 copies, it's more about 0 vs 1 copy. But yes, we can file copy with less copies. > It is a nifty feature, but I think it is more of a niche than simply > saving that 1 copy, because you have to know that the source isn't > going to be used again. Well yes, same as when you free() a page. A little more tricky, but that's mainly the vm assumptions/requirements for page stealing. > But I'll try to support it with begin_write. -- Jens Axboe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
