Jeff Layton wrote:
Here is a different approach to the problem of i_ino uniqueness. Again,
I'll refer to my original email and patch for a description of the
problem...
With this patch, I'm taking the approach of only assigning out an i_ino
value when it's actually needed. This adds a lazy_getattr function. If
i_ino is 0, then this does an iunique and hashes the inode before doing
the actual getattr.
Actually, after having a closer look at this, I don't think this turns
out to be feasible either. Some filesystems (including pipefs) want an
i_ino value early on for generating the qstr passed to d_alloc.
Since they want the value so early, there would be little benefit in
attempting to delay assigning an i_ino value. It might be a win for some
filesystems, but ones like pipefs and sockfs wouldn't be able to use
this scheme, and those are the ones we're primarily concerned with
performance-wise.
I'm going to plan to clean up my IDR patch and resubmit it, as I think
it's probably the best scheme we have that seems to actually fix the
problem.
Unless someone else has a better idea... :-)
-- Jeff
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