Re: [PATCH][2/2] SquashFS

From: Phillip Lougher
Date: Tue Mar 15 2005 - 13:44:02 EST

Andrew Morton wrote:
Phillip Lougher <phillip@xxxxxxxxxxxxxxxxxxx> wrote:

[ on-disk bitfields ]

I've checked compatibilty against Intel 32 and 64 bit architectures, PPC 32/64 bit, ARM, MIPS
and SPARC. I've used compilers from 2.91.x upto 3.4...

hm, OK. I remain a bit skeptical but it sounds like you're the expert. I
guess if things later explode it will be pretty obvious, and the filesystem
will need rework.

One thing which I assume we don't know at this stage is whether all 27
architectures work as expected - you can bet ia64 does it differently ;)

How does one test that? Create a filesystem-in-a-file via mksquashfs, then
transfer that to a different box, then try and mount and use it, I assume?

Yes, slow and laborious, but it works...

When you upissue these patches, please include in the changelog pointers to
the relevant userspace support tools - mksquashfs, fsck.squashfs, etc. I
guess will suit.


Also, this filesystem seems to do the same thing as cramfs. We'd need to
understand in some detail what advantages squashfs has over cramfs to
justify merging it. Again, that is something which is appropriate to the
changelog for patch 1/1.

OK. Squashfs has much better compression and is much faster than cramfs, which is why many embedded systems that used cramfs have moved over to squashfs. Additionally squashfs is used in liveCDs (where cramfs can't be used because of its max 256MB size limit), where it is slowly taking over from cloop, again because it compresses better and is faster.

Both these two groups have been asking for squashfs to be in the mainline kernel.

I can put the above rationale and a pointer to some performance statistics in the changelog, will that be sufficient?

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