Describes in src/RPCAL/nfs_dupreq.c, * The life of tcp drc: it gets allocated when we process the first * request on the connection. It is put into rbtree (tcp_drc_recycle_t). * drc cache maintains a ref count. Every request as well as the xprt * holds a ref count. Its ref count should go to zero when the * connection's xprt gets freed (all requests should be completed on the * xprt by this time). When the ref count goes to zero, it is also put * into a recycle queue (tcp_drc_recycle_q). When a reconnection * happens, we hope to find the same drc that was used before, and the * ref count goes up again. At the same time, the drc will be removed * from the recycle queue. Only drc's with ref count zero end up in the * recycle queue. If a reconnection doesn't happen in time, the drc gets * freed by drc_free_expired() after some period of inactivety.
Some questions about the life time of tcp drc, 1. The are two references of drc for xprt in nfs_dupreq_get_drc(). 629 /* xprt ref */ 630 drc->refcnt = 1; ... 638 (void)nfs_dupreq_ref_drc(drc); /* xprt ref */ ... 653 req->rq_xprt->xp_u2 = (void *)drc; I think it's a bug. The first one needs remove. Right? 2. The is no place to decrease the reference of drc for xprt. The xprt argument in nfs_dupreq_put_drc() is unused. Should it be used to decrease the ref? I think it's the right place to decrease the ref in nfs_dupreq_put_drc(). 3. My doubts is that, the life time of drc stored in req->rq_xprt->xp_u2 ? Start at #1, end at #2 (req->rq_xprt->xp_u2 = NULL) ? If that, the bad case is always lookup drc from tcp_drc_recycle_t. Otherwise, don't put the reference at #2, when to put it? the bad case is the drc ref always be 1 forever, am I right? thanks, Kinglong Mee ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Nfs-ganesha-devel mailing list Nfs-ganesha-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs-ganesha-devel
