Messages in this thread | | | Date | Mon, 09 Sep 2013 14:46:57 -0400 | From | Waiman Long <> | Subject | Re: [PATCH v4 1/1] dcache: Translating dentry into pathname without taking rename_lock |
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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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