Re: [patch] pagecache-2.3.9-H3, bmap & ext2fs cleanup patch

Ingo Molnar (mingo@chiara.csoma.elte.hu)
Sat, 26 Jun 1999 21:39:23 +0200 (CEST)


On Sat, 26 Jun 1999, Linus Torvalds wrote:

> > hm, i cant see any place where we have (!Mapped && Uptodate) in pre4. We
> > have (!Mapped && !Uptodate), but thats normal.
>
> Look at block_read_full_page() - when it sees a zero return from bmap, it
> will clear the block and mark it up-to-date (but never set it Allocated).

oh, i see. (i was used to setting this in the fs, this is why i missed it)
I think encoding holes in this way is bad, it will prevent legitimate uses
of the very same bit-combination: (!Mapped && Uptodate) will be useful if
we'll ever do 'delayed allocation' of filesystem blocks, it will represent
pretty ordinary blocks which are not yet mapped to the filesystem.

-- mingo

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