Messages in this thread | | | Date | Wed, 4 Jan 2012 00:14:32 +0100 | From | Djalal Harouni <> | Subject | Re: [PATCH] fs/ext{3,4}: fix potential race when setversion ioctl updates inode |
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On Tue, Jan 03, 2012 at 01:46:24PM +0100, Jan Kara wrote: > Hello, > > On Tue 03-01-12 02:31:52, Djalal Harouni wrote: > > > > The EXT{3,4}_IOC_SETVERSION ioctl() updates the inode without i_mutex, > > this can lead to a race with the other operations that update the same > > inode. > > > > Patch tested. > Thanks for the patch but I don't quite understand the problem. > i_generation is set when: > a) inode is loaded from disk > b) inode is allocated > c) in SETVERSION ioctl > > The only thing that can race here seems to be c) against c) and that is > racy with i_mutex as well. So what problems do you exactly observe without > the patch? Right, but what about the related i_ctime change ? (i_ctime is updated in other places...)
The i_ctime update must reflect the _appropriate_ inode modification operation. This is why IMHO we should protect them to avoid a lost update.
BTW the i_generation which is used by NFS and fuse filesystems is updated even if the inode is marked immutable, is this the intended behaviour?
> Honza Thanks for your response.
-- tixxdz http://opendz.org
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