[PATCH 06/14] sysfs: Rewrite sysfs_get_dentry
Eric W. Biederman
ebiederm at xmission.com
Wed Aug 1 10:07:39 PDT 2007
Tejun Heo <htejun at gmail.com> writes:
> Hello, Eric.
> Eric W. Biederman wrote:
>> I will look a little more and see. But right now it looks like the
>> real problem with locking is that we use sysfs_mutex to lock the
>> sysfs_dirent s_children list.
>> Instead it really looks like we should use i_mutex from the appropriate
>> inode. Or is there a real performance problem with forcing the directory
>> inodes in core when we modify the directories?
> I don't think there is any performance problem. Problems with using
> i_mutex were...
> * It was messy. I don't remember all the details now but IIRC symlink
> walk code was pretty complex.
> * And more importantly, inodes are reclaimable and might or might not be
Yes. But we can always force inodes into the cache when we need them.
When I complete it I will have to show you a patch using the inode lock
for locking directory modifications. From what I can tell so far it allows
me to fix the weird lock order problems and generally simplify the locking.
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