Messages in this thread | | | Subject | Re: Is there a "make hole" (truncate in middle) syscall? | From | Vladimir Saveliev <> | Date | Fri, 12 Dec 2003 17:01:59 +0300 |
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On Fri, 2003-12-12 at 16:53, Rob Landley wrote: > On Friday 12 December 2003 07:28, Vladimir Saveliev wrote: > > Hi > > > > On Fri, 2003-12-12 at 15:55, Jörn Engel wrote: > > > On Thu, 11 December 2003 14:32:12 -0600, Rob Landley wrote: > > > > On Thursday 11 December 2003 13:48, Jörn Engel wrote: > > > > > If you really do it, please don't add a syscall for it. Simply check > > > > > each written page if it is completely filled with zero. (This will > > > > > be a very quick check for most pages, as they will contain something > > > > > nonzero in the first couple of words) > > > > > > > > Cache poisoning, streaming writes to large RAID arrays... There are > > > > about 8 zllion reasons not to do this. Really. (It defeats the whole > > > > purpose of DMA, doesn't it?) > > > > Sorry, > > but doesn't truncate do almost exactly what "make hole" is supposed to > > do? > > I have a 2 gigabyte file. I want to punch a hole from 257 megabytes to 364 > megabytes, saving over 100 megs of disk space. I do NOT want to have to copy > off and rewrite 1.6 gigabytes of data from the end of the file. (There may > not even be enough room on the disk, and it would take a long time anyway.) > ok. But I asked why would "make hole" have problems you list (8 zillions) and truncate would not have them?
> No, it doesn't do the same thing. Truncate is always to end of file. Punch > hole is like a write, it takes a length. lseek(pos), punch(length). > > Rob > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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