Re: [NFS] [PATCH 016 of 19] knfsd: match GRANTED_RES replies using cookies

Trond Myklebust
2006-09-01T16:03:59Z

On Fri, 2006-09-01 at 14:39 +1000, NeilBrown wrote:
> From: Olaf Kirch <okir@suse.de>
>
> When we send a GRANTED_MSG call, we current copy the NLM cookie
> provided in the original LOCK call - because in 1996, some broken
> clients seemed to rely on this bug. However, this means the cookies
> are not unique, so that when the client's GRANTED_RES message comes
> back, we cannot simply match it based on the cookie, but have to
> use the client's IP address in addition. Which breaks when you have
> a multi-homed NFS client.
>
> The X/Open spec explicitly mentions that clients should not expect the
> same cookie; so one may hope that any clients that were broken in 1996
> have either been fixed or rendered obsolete.

Vetoed. The reason why we need the client's IP address as an argument
for nlmsvc_find_block() is 'cos the cookie value is unique to the
_client_ only.

IOW: when we go searching a global list of blocks for a given cookie
value that was sent to us by a given client, then we want to know that
we're only searching through that particular client's blocks.

A better way, BTW, would be to get rid of the global list nlm_blocked,
and just move the list of blocks into a field in the nlm_host for each
client.

> Signed-off-by: Olaf Kirch <okir@suse.de>
> Signed-off-by: Neil Brown <neilb@suse.de>
>
> ### Diffstat output
> ./fs/lockd/svc4proc.c | 2 +-
> ./fs/lockd/svclock.c | 24 +++++++++++++-----------
> ./fs/lockd/svcproc.c | 2 +-
> ./include/linux/lockd/lockd.h | 2 +-
> 4 files changed, 16 insertions(+), 14 deletions(-)
>
> diff .prev/fs/lockd/svc4proc.c ./fs/lockd/svc4proc.c
> --- .prev/fs/lockd/svc4proc.c 2006-09-01 12:11:01.000000000 +1000
> +++ ./fs/lockd/svc4proc.c 2006-09-01 12:17:21.000000000 +1000
> @@ -455,7 +455,7 @@ nlm4svc_proc_granted_res(struct svc_rqst
>
> dprintk("lockd: GRANTED_RES called\n");
>
> - nlmsvc_grant_reply(rqstp, &argp->cookie, argp->status);
> + nlmsvc_grant_reply(&argp->cookie, argp->status);
> return rpc_success;
> }
>
>
> diff .prev/fs/lockd/svclock.c ./fs/lockd/svclock.c
> --- .prev/fs/lockd/svclock.c 2006-09-01 12:11:01.000000000 +1000
> +++ ./fs/lockd/svclock.c 2006-09-01 12:17:21.000000000 +1000
> @@ -139,19 +139,19 @@ static inline int nlm_cookie_match(struc
> * Find a block with a given NLM cookie.
> */
> static inline struct nlm_block *
> -nlmsvc_find_block(struct nlm_cookie *cookie, struct sockaddr_in *sin)
> +nlmsvc_find_block(struct nlm_cookie *cookie)
> {
> struct nlm_block *block;
>
> list_for_each_entry(block, &nlm_blocked, b_list) {
> - if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie)
> - && nlm_cmp_addr(sin, &block->b_host->h_addr))
> + if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
> goto found;
> }
>
> return NULL;
>
> found:
> + dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
> kref_get(&block->b_count);
> return block;
> }
> @@ -165,6 +165,11 @@ found:
> * request, but (as I found out later) that's because some implementations
> * do just this. Never mind the standards comittees, they support our
> * logging industries.
> + *
> + * 10 years later: I hope we can safely ignore these old and broken
> + * clients by now. Let's fix this so we can uniquely identify an incoming
> + * GRANTED_RES message by cookie, without having to rely on the client's IP
> + * address. --okir
> */
> static inline struct nlm_block *
> nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
> @@ -197,7 +202,7 @@ nlmsvc_create_block(struct svc_rqst *rqs
> /* Set notifier function for VFS, and init args */
> call->a_args.lock.fl.fl_flags |= FL_SLEEP;
> call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
> - call->a_args.cookie = *cookie; /* see above */
> + nlmclnt_next_cookie(&call->a_args.cookie);
>
> dprintk("lockd: created block %p...\n", block);
>
> @@ -640,17 +645,14 @@ static const struct rpc_call_ops nlmsvc_
> * block.
> */
> void
> -nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
> +nlmsvc_grant_reply(struct nlm_cookie *cookie, u32 status)
> {
> struct nlm_block *block;
> - struct nlm_file *file;
>
> - dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n",
> - *(unsigned int *)(cookie->data),
> - ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
> - if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
> + dprintk("grant_reply: looking for cookie %x, s=%d \n",
> + *(unsigned int *)(cookie->data), status);
> + if (!(block = nlmsvc_find_block(cookie)))
> return;
> - file = block->b_file;
>
> if (block) {
> if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
>
> diff .prev/fs/lockd/svcproc.c ./fs/lockd/svcproc.c
> --- .prev/fs/lockd/svcproc.c 2006-09-01 12:11:01.000000000 +1000
> +++ ./fs/lockd/svcproc.c 2006-09-01 12:17:21.000000000 +1000
> @@ -484,7 +484,7 @@ nlmsvc_proc_granted_res(struct svc_rqst
>
> dprintk("lockd: GRANTED_RES called\n");
>
> - nlmsvc_grant_reply(rqstp, &argp->cookie, argp->status);
> + nlmsvc_grant_reply(&argp->cookie, argp->status);
> return rpc_success;
> }
>
>
> diff .prev/include/linux/lockd/lockd.h ./include/linux/lockd/lockd.h
> --- .prev/include/linux/lockd/lockd.h 2006-09-01 12:17:03.000000000 +1000
> +++ ./include/linux/lockd/lockd.h 2006-09-01 12:17:21.000000000 +1000
> @@ -193,7 +193,7 @@ u32 nlmsvc_cancel_blocked(struct nlm_
> unsigned long nlmsvc_retry_blocked(void);
> void nlmsvc_traverse_blocks(struct nlm_host *, struct nlm_file *,
> nlm_host_match_fn_t match);
> -void nlmsvc_grant_reply(struct svc_rqst *, struct nlm_cookie *, u32);
> +void nlmsvc_grant_reply(struct nlm_cookie *, u32);
>
> /*
> * File handling for the server personality
>
> -------------------------------------------------------------------------
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