[RFC PATCH 3/3] fs: detect that the i_rwsem has already been taken exclusively

Linus Torvalds torvalds at linux-foundation.org
Thu Sep 28 23:39:23 UTC 2017

On Thu, Sep 28, 2017 at 3:02 PM, Dave Chinner <david at fromorbit.com> wrote:
> On Thu, Sep 28, 2017 at 08:39:33AM -0400, Mimi Zohar wrote:
>> Don't attempt to take the i_rwsem, if it has already been taken
>> exclusively.
>> Signed-off-by:  Mimi Zohar <zohar at linux.vnet.ibm.com>
> That's bloody awful.
> The locking in filesystem IO paths is already complex enough without
> adding a new IO path semantic that says "caller has already locked
> the i_rwsem in some order and some dependencies that we have no idea
> about".

I do have to admit that I never got a satisfactory answer on why IMA
doesn't just use its own private per-inode lock for this all.

It isn't using the i_rwsem for file consistency reasons anyway, so it
seems to be purely about serializing the actual signature generation
with the xattr writing, but since IMA does those both, why isn't IMA
just using its own lock (not the filesystem lock) to do that?

To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

More information about the Linux-security-module-archive mailing list