On Feb 14, 2012, at 8:50 PM, Myklebust, Trond wrote:
> On Tue, 2012-02-14 at 19:53 -0500, J. Bruce Fields wrote:
>> On Wed, Feb 15, 2012 at 12:43:08AM +0000, Myklebust, Trond wrote:
>>> Then we have a problem. The zero initialisation is already in use out
>>> there in both commercial and non-commercial versions of Linux. It is too
>>> late to change that now.
>>>
>>> Furthermore, since none of the servers we've tested against in earlier
>>> Bakeathons and Connectathons have complained, I suggest that we rather
>>> change the spec with an errata.
>>
>> Argh.
>>
>> I just noticed that the server was crashing intermittently and traced it
>> to incorrect handling of the case where the client sends a one-op
>> SEQUENCE compound with seqid 0. I'm not sure why it started popping up
>> just in 3.3--perhaps some change in the way the client uses slots made
>> that more likely.
>>
>> The server code actually looks like it did assume initial seqid 1, but
>> accepted initial seqid 0 (except in this one case) basically by mistake.
>>
>> In any case, I think it should be easy enough to teach it just to accept
>> any seqid on a previously unused slot, so I'll do that....
>
> Hang on... Looking at 3.2, I think you're correct. We used to initialise
> to 1, and now we're initialising to 0.
No, commit aacd5537270a752fe12a9914a207284fc2341c6d initializes and resets the slot tables with the ivalue which is 1 for the forechannel and 0 for the back channel, just as in 3.2.
To be clear from aacd5537:
-static int nfs4_init_slot_tables(struct nfs4_session *session)
+static int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
{
struct nfs4_slot_table *tbl;
- int status = 0;
+ int status;
- tbl = &session->fc_slot_table;
+ dprintk("--> %s\n", __func__);
+ /* Fore channel */
+ tbl = &ses->fc_slot_table;
if (tbl->slots == NULL) {
- status = nfs4_init_slot_table(tbl,
- session->fc_attrs.max_reqs, 1);
^^^^^^^
ivalue of 1
+ status = nfs4_init_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
^^^^^
ivalue of 1
+ if (status) /* -ENOMEM */
+ return status;
+ } else {
+ status = nfs4_reset_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
^^^^^
ivalue of 1
if (status)
return status;
}
-
- tbl = &session->bc_slot_table;
+ /* Back channel */
+ tbl = &ses->bc_slot_table;
if (tbl->slots == NULL) {
- status = nfs4_init_slot_table(tbl,
- session->bc_attrs.max_reqs, 0);
+ status = nfs4_init_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
if (status)
- nfs4_destroy_slot_tables(session);
- }
-
+ /* Fore and back channel share a connection so get
+ * both slot tables or neither */
+ nfs4_destroy_slot_tables(ses);
+ } else
+ status = nfs4_reset_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
return status;
}
-->Andy
>
> Ah... I see what happened.
>
> commit aacd5537270a752fe12a9914a207284fc2341c6d (NFSv4.1: cleanup init
> and reset of session slot tables) seems to have removed the call to
> nfs4_reset_slot_tables() that was doing that initialisation. OK.
> this is a Linux 3.3-rcX only regression, and should be treated as
> such...
>
> How about the following instead so that we ensure we fully share the
> initialisation code between nfs4_reset_slot_tables and
> nfs4_init_slot_tables?
>
> 8<-------------------------------------------------------------------------
> From 8ae8d177cc106ecdb3e29b48c78ec37cf76ea549 Mon Sep 17 00:00:00 2001
> From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> Date: Tue, 14 Feb 2012 20:33:19 -0500
> Subject: [PATCH] NFSv4.1: Fix a NFSv4.1 session initialisation regression
>
> Commit aacd553 (NFSv4.1: cleanup init and reset of session slot tables)
> introduces a regression in the session initialisation code. New tables
> now find their sequence ids initialised to 0, rather than the mandated
> value of 1 (see RFC5661).
>
> Reported-by: Vitaliy Gusev <gusev.vitaliy@xxxxxxxxxxx>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> ---
> fs/nfs/nfs4proc.c | 58 ++++++++++++++++++++++++++++++++---------------------
> 1 files changed, 35 insertions(+), 23 deletions(-)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index d202e04..9f76ce9 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -5008,37 +5008,53 @@ int nfs4_proc_get_lease_time(struct nfs_client *clp, struct nfs_fsinfo *fsinfo)
> return status;
> }
>
> +static struct nfs4_slot *nfs4_session_alloc_slots(u32 max_slots, gfp_t gfp_flags)
> +{
> + return kcalloc(max_slots, sizeof(struct nfs4_slot), gfp_flags);
> +}
> +
> +static void nfs4_session_add_slots(struct nfs4_slot_table *tbl,
> + struct nfs4_slot *new,
> + u32 max_slots,
> + u32 ivalue)
> +{
> + struct nfs4_slot *old = NULL;
> + u32 i;
> +
> + spin_lock(&tbl->slot_tbl_lock);
> + if (new) {
> + old = tbl->slots;
> + tbl->slots = new;
> + tbl->max_slots = max_slots;
> + }
> + tbl->highest_used_slotid = -1; /* no slot is currently used */
> + for (i = 0; i < tbl->max_slots; i++)
> + tbl->slots[i].seq_nr = ivalue;
> + spin_unlock(&tbl->slot_tbl_lock);
> + kfree(old);
> +}
> +
> /*
> * Reset a slot table
> */
> static int nfs4_reset_slot_table(struct nfs4_slot_table *tbl, u32 max_reqs,
> - int ivalue)
> + u32 ivalue)
> {
> struct nfs4_slot *new = NULL;
> - int i;
> - int ret = 0;
> + int ret = -ENOMEM;
>
> dprintk("--> %s: max_reqs=%u, tbl->max_slots %d\n", __func__,
> max_reqs, tbl->max_slots);
>
> /* Does the newly negotiated max_reqs match the existing slot table? */
> if (max_reqs != tbl->max_slots) {
> - ret = -ENOMEM;
> - new = kmalloc(max_reqs * sizeof(struct nfs4_slot),
> - GFP_NOFS);
> + new = nfs4_session_alloc_slots(max_reqs, GFP_NOFS);
> if (!new)
> goto out;
> - ret = 0;
> - kfree(tbl->slots);
> }
> - spin_lock(&tbl->slot_tbl_lock);
> - if (new) {
> - tbl->slots = new;
> - tbl->max_slots = max_reqs;
> - }
> - for (i = 0; i < tbl->max_slots; ++i)
> - tbl->slots[i].seq_nr = ivalue;
> - spin_unlock(&tbl->slot_tbl_lock);
> + ret = 0;
> +
> + nfs4_session_add_slots(tbl, new, max_reqs, ivalue);
> dprintk("%s: tbl=%p slots=%p max_slots=%d\n", __func__,
> tbl, tbl->slots, tbl->max_slots);
> out:
> @@ -5064,7 +5080,7 @@ static void nfs4_destroy_slot_tables(struct nfs4_session *session)
> * Initialize slot table
> */
> static int nfs4_init_slot_table(struct nfs4_slot_table *tbl,
> - int max_slots, int ivalue)
> + u32 max_slots, u32 ivalue)
> {
> struct nfs4_slot *slot;
> int ret = -ENOMEM;
> @@ -5073,16 +5089,12 @@ static int nfs4_init_slot_table(struct nfs4_slot_table *tbl,
>
> dprintk("--> %s: max_reqs=%u\n", __func__, max_slots);
>
> - slot = kcalloc(max_slots, sizeof(struct nfs4_slot), GFP_NOFS);
> + slot = nfs4_session_alloc_slots(max_slots, GFP_NOFS);
> if (!slot)
> goto out;
> ret = 0;
>
> - spin_lock(&tbl->slot_tbl_lock);
> - tbl->max_slots = max_slots;
> - tbl->slots = slot;
> - tbl->highest_used_slotid = -1; /* no slot is currently used */
> - spin_unlock(&tbl->slot_tbl_lock);
> + nfs4_session_add_slots(tbl, slot, max_slots, ivalue);
> dprintk("%s: tbl=%p slots=%p max_slots=%d\n", __func__,
> tbl, tbl->slots, tbl->max_slots);
> out:
> --
> 1.7.7.6
>
>
> --
> Trond Myklebust
> Linux NFS client maintainer
>
> NetApp
> Trond.Myklebust@xxxxxxxxxx
> www.netapp.com
>
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