From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754107Ab3BDAQE (ORCPT ); Sun, 3 Feb 2013 19:16:04 -0500 Received: from fieldses.org ([174.143.236.118]:36440 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753885Ab3BDAQC (ORCPT ); Sun, 3 Feb 2013 19:16:02 -0500 Date: Sun, 3 Feb 2013 19:15:58 -0500 From: "J. Bruce Fields" To: Tejun Heo Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, skinsbursky@parallels.com, ebiederm@xmission.com, jmorris@namei.org, axboe@kernel.dk Subject: Re: [PATCHSET] idr: implement idr_alloc() and convert existing users Message-ID: <20130204001557.GB24778@fieldses.org> References: <1359854463-2538-1-git-send-email-tj@kernel.org> <20130203170241.GA24778@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130203170241.GA24778@fieldses.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 03, 2013 at 12:02:41PM -0500, J. Bruce Fields wrote: > On Sat, Feb 02, 2013 at 05:20:01PM -0800, Tejun Heo wrote: > > * Bruce, I couldn't convert nfsd. Can you please help? More on it > > later. > ... > > I converted all in-kernel users except nfsd and staging drivers. nfsd > > splits preloading and actual id allocation in a way that per-cpu > > preloading can't be used. I couldn't follow the control flow to > > verify whether the current code is correct either. I think the best > > way would be allocating ID upfront without installing the handle and > > then later using idr_replace() to install the pointer when the ID > > actually gets used. Bruce, would something like that be possible? > > Actually, I'm not even sure if that's necessary, we can probably just > do it all at the start. > > I'll try to have a patch doing that tomorrow. So, something like this. --b. commit 9847160469b40345e1d78a7cbf9536761bb47d91 Author: J. Bruce Fields Date: Sun Feb 3 12:23:01 2013 -0500 nfsd4: simplify idr allocation We don't really need to preallocate at all; just allocate and initialize everything at once, but leave the sc_type field initially 0 to prevent finding the stateid till it's fully initialized. Signed-off-by: J. Bruce Fields diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 4db46aa..485b1f7 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -261,33 +261,46 @@ static inline int get_new_stid(struct nfs4_stid *stid) return new_stid; } -static void init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, unsigned char type) +static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct +kmem_cache *slab) { - stateid_t *s = &stid->sc_stateid; + struct idr *stateids = &cl->cl_stateids; + static int min_stateid = 0; + struct nfs4_stid *stid; int new_id; - stid->sc_type = type; + stid = kmem_cache_alloc(slab, GFP_KERNEL); + if (!stid) + return NULL; + + if (!idr_pre_get(stateids, GFP_KERNEL)) + goto out_free; + if (idr_get_new_above(stateids, stid, min_stateid, &new_id)) + goto out_free; stid->sc_client = cl; - s->si_opaque.so_clid = cl->cl_clientid; - new_id = get_new_stid(stid); - s->si_opaque.so_id = (u32)new_id; + stid->sc_type = 0; + stid->sc_stateid.si_opaque.so_id = new_id; + stid->sc_stateid.si_opaque.so_clid = cl->cl_clientid; /* Will be incremented before return to client: */ - s->si_generation = 0; -} + stid->sc_stateid.si_generation = 0; -static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab) -{ - struct idr *stateids = &cl->cl_stateids; - - if (!idr_pre_get(stateids, GFP_KERNEL)) - return NULL; /* - * Note: if we fail here (or any time between now and the time - * we actually get the new idr), we won't need to undo the idr - * preallocation, since the idr code caps the number of - * preallocated entries. + * It shouldn't be a problem to reuse an opaque stateid value. + * I don't think it is for 4.1. But with 4.0 I worry that, for + * example, a stray write retransmission could be accepted by + * the server when it should have been rejected. Therefore, + * adopt a trick from the sctp code to attempt to maximize the + * amount of time until an id is reused, by ensuring they always + * "increase" (mod INT_MAX): */ - return kmem_cache_alloc(slab, GFP_KERNEL); + + min_stateid = new_id+1; + if (min_stateid == INT_MAX) + min_stateid = 0; + return stid; +out_free: + kfree(stid); + return NULL; } static struct nfs4_ol_stateid * nfs4_alloc_stateid(struct nfs4_client *clp) @@ -316,7 +329,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab)); if (dp == NULL) return dp; - init_stid(&dp->dl_stid, clp, NFS4_DELEG_STID); + dp->dl_stid.sc_type = NFS4_DELEG_STID; /* * delegation seqid's are never incremented. The 4.1 special * meaning of seqid 0 isn't meaningful, really, but let's avoid @@ -337,13 +350,21 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv return dp; } +void free_stid(struct nfs4_stid *s, struct kmem_cache *slab) +{ + struct idr *stateids = &s->sc_client->cl_stateids; + + idr_remove(stateids, s->sc_stateid.si_opaque.so_id); + kmem_cache_free(slab, s); +} + void nfs4_put_delegation(struct nfs4_delegation *dp) { if (atomic_dec_and_test(&dp->dl_count)) { dprintk("NFSD: freeing dp %p\n",dp); put_nfs4_file(dp->dl_file); - kmem_cache_free(deleg_slab, dp); + free_stid(&dp->dl_stid, deleg_slab); num_delegations--; } } @@ -360,9 +381,7 @@ static void nfs4_put_deleg_lease(struct nfs4_file *fp) static void unhash_stid(struct nfs4_stid *s) { - struct idr *stateids = &s->sc_client->cl_stateids; - - idr_remove(stateids, s->sc_stateid.si_opaque.so_id); + s->sc_type = 0; } /* Called under the state lock. */ @@ -519,7 +538,7 @@ static void close_generic_stateid(struct nfs4_ol_stateid *stp) static void free_generic_stateid(struct nfs4_ol_stateid *stp) { - kmem_cache_free(stateid_slab, stp); + free_stid(&stp->st_stid, stateid_slab); } static void release_lock_stateid(struct nfs4_ol_stateid *stp) @@ -1258,7 +1277,12 @@ static void gen_confirm(struct nfs4_client *clp) static struct nfs4_stid *find_stateid(struct nfs4_client *cl, stateid_t *t) { - return idr_find(&cl->cl_stateids, t->si_opaque.so_id); + struct nfs4_stid *ret; + + ret = idr_find(&cl->cl_stateids, t->si_opaque.so_id); + if (!ret || !ret->sc_type) + return NULL; + return ret; } static struct nfs4_stid *find_stateid_by_type(struct nfs4_client *cl, stateid_t *t, char typemask) @@ -2444,9 +2468,8 @@ alloc_init_open_stateowner(unsigned int strhashval, struct nfs4_client *clp, str static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) { struct nfs4_openowner *oo = open->op_openowner; - struct nfs4_client *clp = oo->oo_owner.so_client; - init_stid(&stp->st_stid, clp, NFS4_OPEN_STID); + stp->st_stid.sc_type = NFS4_OPEN_STID; INIT_LIST_HEAD(&stp->st_lockowners); list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids); list_add(&stp->st_perfile, &fp->fi_stateids); @@ -4032,7 +4055,7 @@ alloc_init_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp, struct stp = nfs4_alloc_stateid(clp); if (stp == NULL) return NULL; - init_stid(&stp->st_stid, clp, NFS4_LOCK_STID); + stp->st_stid.sc_type = NFS4_LOCK_STID; list_add(&stp->st_perfile, &fp->fi_stateids); list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids); stp->st_stateowner = &lo->lo_owner;