Messages in this thread | | | Date | Wed, 4 Jun 1997 20:47:11 +0100 | From | "Stephen C. Tweedie" <> | Subject | Re: Ext2fs and hashed table. |
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Hi,
On Wed, 4 Jun 1997 04:41:23 +0200 (Funky), Matthias Urlichs <smurf@work.smurf.noris.de> said:
> Hi, > Stephen C. Tweedie wrote: >> >> [ extent mapping ] >> >> The main problem with this technique is that it completely falls apart >> when you consider Unix semantics for files with holes --- you end up >> having to reshuffle the entire extent map any time you insert new data >> by writing into a hole. The current plan is simply to convert >> on-the-fly from extent mapped to direct indexed block mapping if such >> a write occurs. >> > Moving the extent mp around shouldn't be _too_ difficult...
The trouble is that you have to do it for _every_ write request in the hole, unless you do fancy things with the tree and have a sparse map --- in which case you're losing a lot of the intended efficiency gain anyway. The direct map table seems to be a better idea all round for writing into holes.
Cheers, Stephen.
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