Messages in this thread | | | Date | Wed, 16 Jul 2008 15:48:39 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 12/15] driver core: Implement tagged directory support for device classes. |
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Hello, Eric.
Eric W. Biederman wrote: > Tejun Heo <htejun@gmail.com> writes: > >> It's a bit scary tho. Working inode->i_dentry or dentry->d_alias >> crosses multiple sb's. sysfs isn't too greedy about dcache/icache. >> Only open files and directories hold them and only single copy of >> sysfs_dirent is there for most nodes. Wouldn't it be better to stay on >> the safer side and use separate inode hierarchy? > > To do that I believe we would need to ensure sysfs does not use > the inode->i_mutex lock except to keep the VFS layer out. Allowing us > to safely change the directory structure, without holding it.
I don't think sysfs is depending on i_mutex anymore but I need to go through the code to make sure.
> You raise a good point about inode->i_dentry and dentry->d_alias. > Generally they are used by fat like filesystems but I am starting to > see uses in generic pieces of code. I don't see any problems today > but yes it would be good to do the refactoring to allow us to duplicate > the inodes.
Yeah, I can't spot any place which can cause actual problem yet but it's still scary as we're breaking a vfs assumption and even if it's not a problem now, future seemingly unrelated changes can break things subtly.
Thanks.
-- tejun
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