Re: [PATCH v3 10/12] ima: defer calling __fput()

["Kasatkin, Dmitry" <dmitry.kasatkin@xxxxxxxxx>]

On Thu, Mar 22, 2012 at 5:09 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> On Thu, Mar 22, 2012 at 10:53:04AM -0400, Mimi Zohar wrote:
>> > BTW, you've missed several other places in mm/* doing fput(), so it wouldn't
>> > be enough to paper over your problem anyway.
>> >
>> > Final fput() *can* happen under mmap_sem.  Period.
>>
>> I think I got that loud and clear; otherwise we wouldn't have come up
>> with deferring the __fput().  We have a very real problem here - writing
>> extended attributes requires taking the i_mutex.
>
> Don't do it, then?  If you _must_ write to xattr on final fput, I'd suggest
> starting to figure out if xattr needs its protection to be ->i_mutex - it
> might make sense to introduce a separate mutex for xattr crap.  Or not - I'm

"Or not" ... How to understand you?

> not familiar enough with the guts of xattr handling in individual filesystems
> to tell if that would work (e.g. if it would need unpleasant changes to
> ->setattr() instances)...
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