On Thu, Sep 28, 2017 at 3:02 PM, Dave Chinner [off-list ref] wrote:
On Thu, Sep 28, 2017 at 08:39:33AM -0400, Mimi Zohar wrote:
quoted
Don't attempt to take the i_rwsem, if it has already been taken
exclusively.
Signed-off-by: Mimi Zohar <redacted>
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?
Linus
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