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[Dazuko-devel] 2.0.5-pre4 posted

From: John Ogness
Subject: [Dazuko-devel] 2.0.5-pre4 posted
Date: Tue, 18 Jan 2005 22:02:54 +0100
User-agent: Mozilla Thunderbird 0.9 (X11/20041114)


I have posted another pre-release of 2.0.5. The last pre-release caused a lot of problems with the __d_path() function (specifically, with vfsmount_lock). This turns out to be a much bigger problem than I first thought.

The problem: __d_path(), a critical function for performing full path name lookups, is not exported to kernel modules. Dazuko could have its own copy of this function except that the function uses a kernel lock (vfsmount_lock) that is also not exported to kernel modules.

The solution: On non-SMP kernels the lock is irrelevant because non-SMP kernels don't use kernel locks. This means that for non-SMP kernels, Dazuko can use an internal copy of the __d_path() function. However, SMP kernels do need kernel locks and therefore *must* use the "real" __d_path() function in the kernel. In order to do this, the __d_path() function must be exported. A very small kernel patch is now provided with the Dazuko package to export the function.

For SMP kernels, this means that the kernel source must be patched and a new kernel built. I hate this as much as you do, but there is no way around it. Some distributions (such as Fedora Core) already export __d_path(), so a kernel patch/rebuild isn't necessary. Hopefully more distributions (and maybe even the "vanilla" kernel) will once again export this function.

Also included in the Dazuko package is a README.linux26 file that explains this. The "configure" script also produces a warning if you have an SMP kernel and suggests reading the README.linux26 file.

I am open for comments/suggestions about this. I don't know what else to do.

I normally don't post these announcements to dazuko-help, but I felt that this information was important (although a bit technical).

John Ogness

Dazuko Maintainer

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