On Wed, Apr 08, 2015 at 06:21:04PM +0200, Christoph Hellwig wrote: > On Tue, Apr 07, 2015 at 05:07:47PM -0400, J. Bruce Fields wrote: > > On Tue, Apr 07, 2015 at 05:35:44PM +0200, Christoph Hellwig wrote: > > > We want to drop all I/O path locks when recalling layouts, and that includes > > > i_mutex for the write path. Without this we get stuck processe when recalls > > > take too long. > > > > Also if the writer is an nfsd thread than we'd rather just error out > > than wait. (To be clear: ACK to this patch as far as I'm concerned, I've got another concern but we need this fix regardless.) > We have no way to know we are called by nfsd here unfortunately. I was imagining the possible deadlock here as mostly theoretical, but now that I think of it it doesn't sound unlikely at all: - file is under heavy write load - conflicting operation breaks layout - nfsd threads all block in writes to that file - no nfsd threads available to service layout return - recall times out, client fenced. Ugh. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
