Roger Leigh wrote: > There are lots of Debian people out there using git, and some of them > have expressed interest over the years in having the ability to use > git as a filesystem in its own right (#477942 is an example of one > in a package I maintain). > > I've finally got down to it and written all my thoughts on the topic > down in a mostly-organised form, which you can find at > > http://www.codelibre.net/~rleigh/hashlink.pdf > > This paper looks at the concept of object-based storage, and the > creation of "hashlinks", essentially symlinks which use hashes > rather than pathnames to refer to a file.
You may be interested in my git-annex program, which implements just such a thing, although in user space, not kernel space. http://git-annex.branchable.com/ joey@gnu:~/lib/sound/misc>ls -l dj_mooch_-_misc_-_01_-_dirty_as_mud.mp3 lrwxrwxrwx 1 joey joey 113 Nov 9 14:09 dj_mooch_-_misc_-_01_-_dirty_as_mud.mp3 -> ../.git/annex/objects/SHA1:717566db4265b4b3a986ba84e797df56c25923be/SHA1:717566db4265b4b3a986ba84e797df56c25923be Note that once you have a hashlink, you can know that if another filesystem elsewhere has the same hashlink, the content can be retrieved from there. So the deduplication and general content management can be done cross-filesystem. That is a basis of much of the good stuff git-annex can do. For example: joey@gnu:~/lib/big/new>ls -l debian-6.0.0-amd64-i386-netinst.iso lrwxrwxrwx 1 joey joey 145 Feb 6 14:10 debian-6.0.0-amd64-i386-netinst.iso -> ../.git/annex/objects/WORM:1296961374:432142336:debian-6.0.0-amd64-i386-netinst.iso/WORM:1296961374:432142336:debian-6.0.0-amd64-i386-netinst.iso joey@gnu:~/lib/big/new>git log --pretty=oneline debian-6.0.0-amd64-i386-netinst.iso 97dc2f3a5b5aec7671c7f282b8ea42a89f90b44a pre passport-sync joey@gnu:~/lib/big/new>cat debian-6.0.0-amd64-i386-netinst.iso cat: debian-6.0.0-amd64-i386-netinst.iso: No such file or directory joey@gnu:~/lib/big/new>git annex get debian-6.0.0-amd64-i386-netinst.iso get debian-6.0.0-amd64-i386-netinst.iso (copying from turtle...) Also, Josh Triplett has some ideas about integrating git with dpkg for fully versioned systems. I'm not sure if he's ready to make them public, but you may find talking with him interesting. -- see shy jo
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