On 09/09/2013 02:36 PM, Al Viro wrote:
On Mon, Sep 09, 2013 at 07:21:11PM +0100, Al Viro wrote:
Actually, it's better for prepend_path() as well, because it's actually
rcu_read_lock();
seq = read_seqbegin(&rename_lock);
again:
....
if (error)
goto done;
....
if (!seqretry_and_lock(&rename_lock, seq))
goto again; /* now as writer */
done:
seqretry_done(&rename_lock, seq);
rcu_read_unlock();
Posted variant will sometimes hit the following path:
* seq_readlock()
* start generating the output
* hit an error
[another process has taken and released rename_lock for some reason]
* hit read_seqretry_and_unlock(), which returns 1.
* retry everything with seq_writelock(), despite the error.
It's not too horrible (we won't be looping indefinitely, ignoring error
all along), but it's certainly subtle enough...
FWIW, what I propose is this (just the d_path-related parts):
I am fine with your proposed change as long as it gets the job done. It
doesn't really matter if you do it or I do it.
Thank for taking the effort to make it better for us all.
-Longman
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