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Re: How to access loop-aes mounted vfat filesystem as non-root user- help required!

Jari Ruusu wrote:
Matthias Schniedermeyer wrote:

For the filesystem any block device looks the same, regardless if it is a
HDD, FDD, a(n encrypted-)loop or whatever else is used to satisfy the
issued requests.



Actually block devices have differences that file systems have to deal with:
1)  Hard sector sizes may be different. File system code must detect block
    device hard sector size and avoid issuing partial sector accesses.
2)  Some device drivers don't support variable length read/write requests.
    XFS for example had (has?) list of 'problematic' devices that needed
    fixed size read/write requests. IIRC, md raid on 2.4 kernels was such
    block device that got upset when banged with variable length requests.
3)  Some block devices support write barriers on 2.6 kernels, some don't.
    A file system that wants to issue barrier write requests have to work
    around the not supported cases.
4)  Maximum request sizes and bunch of other limits may be different.

OK. That was new to me.

I change my paragrah to:
For the filesystem most block devices look pretty much the same. There are a few special cases, but they are only relevant for filesystem developers.

:-)



Bis denn

--
Real Programmers consider "what you see is what you get" to be just as
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated,
cryptic, powerful, unforgiving, dangerous.


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