Messages in this thread | | | Date | Sat, 26 Jun 1999 13:21:36 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [patch] pagecache-2.3.9-H3, bmap & ext2fs cleanup patch |
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On Sat, 26 Jun 1999, Ingo Molnar wrote: > > delayed write. So let me modify my original claim to be that "Hole" is > > useless, because it is exactly the same as > > > > "!Mapped && !Dirty && Uptodate" > > > > Ok? > > i think this is just playing tricks with _currently_ invalid > bitcombinations.
No.
The code is much simpler and much more straightforward, and it makes sense. No "tricks" involved.
See it my way:
- I have simpler code, with one less made-up bit of information. If you look at the patches, you'll notice that NOTHING actually ever needs to test the above combination - it just falls out as the natural behaviour.
vs
- more complex code, with more state, that doesn't give anything new and adds more rules that have to be tested for.
So obviously I'll drop the BH_Hole bit - it isn't buying us anything at all, and it _is_ setting us up for coherency problems.
> !Mapped && Uptodate && !Dirty can be a valid combination > in the future as well - we might want to destroy buffer-heads (the > mapping) under a data block for legitimate reasons, eg. in the future it > might be possible to move the device under a filesystem, or we simply have > a filesystem with nonpermanent mappings, eg. a filesystem might choose to > destroy the mapping after the IO has been finished.
I'll believe you when I see it. My motto is: never overdesign. It sounds like you're making up reasons to overdesign something that isn't needed.
Linus
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