On 19 March 2010 20:03, Valerie Aurora <vaurora@xxxxxxxxxx> wrote: > On Fri, Mar 19, 2010 at 01:21:53AM +0100, Michal Suchanek wrote: >> Hello >> >> I was wondering in what state is the Linux UnionMount. As all other >> union solutions were rejected from the kernel so far the development >> on them is stagnating and it's not exactly easy to get them patched on >> top of new kernels. >> >> There is a repo at >> http://git.kernel.org/?p=linux/kernel/git/val/linux-2.6.git;a=summary >> >> which has tags for some older kernels up to 2.6.32-rc5 and the code >> does not seem merged into current kernels such as 2.6.34-rc1, I don't >> see it in config. > > Where union mounts is right now is in need of more review from VFS > experts (and thanks to those who have already reviewed it). I'm > rewriting the in-file copyup code right now, which is dependent on a > lot of ongoing VFS work by Al Viro, Nick Piggin, Dmitriy Monakhov, and > others. Here's my description of the problem I'm currently working, > which is where I could use review the most: > > http://groups.google.com/group/linux.kernel/msg/217ca5aedbd7bfd0 > > Like anyone else, VFS developers prioritize what they are working on, > and unioning file systems in general tend to be low on the list. > Union mounts is my first priority but not anyone else's. :) > > Thanks for your email, > > -VAL > > Hello How is the unionmount going along? I see multiple branches based off 2.6.34 kernel in the git repo. Reading the doc I find a few points quite unsetting: 99 What happens when I... 100 101 - creat() /newfile -> creates on topmost layer 102 - unlink() /oldfile -> creates a whiteout on topmost layer 103 - Edit /existingfile -> copies up to top layer at open(O_WR) time 104 - truncate /existingfile -> copies up to topmost layer + N bytes if specified 105 - touch()/chmod()/chown()/etc. -> copies up to topmost layer I'm not sure if touching a file is common operation for non-zero files. Somebody might want working atimes in the shared root use case so there should be an optimization in place for this case. 106 - mkdir() /newdir -> creates on topmost layer Does this mean that the mkdir() can succeed if there is no directory in topmost layer and there is one in the bottom layer? That's certainly not what mkdir should do. Thanks Michal -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
