Commit 0b175b18 authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Add tracepoints to NFSD's duplicate reply cache 



Try to capture DRC failures.

Two additional clean-ups:
- Introduce Doxygen-style comments for the main entry points
- Remove a dprintk that fires for an allocation failure. This was
  the only dprintk in the REPCACHE class.

Reported-by: default avatarkbuild test robot <lkp@intel.com>
[ cel: force typecast for display of checksum values ]
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent d88ff958

fs/nfsd/nfscache.c

+35 −22
Original line number Diff line number Diff line
@@ -20,8 +20,7 @@ 


#include "nfsd.h"

#include "cache.h"



#define NFSDDBG_FACILITY	NFSDDBG_REPCACHE

#include "trace.h"



/*

 * We use this value to determine the number of hash buckets from the max
@@ -323,8 +322,10 @@ nfsd_cache_key_cmp(const struct svc_cacherep *key, 
			const struct svc_cacherep *rp, struct nfsd_net *nn)

{

	if (key->c_key.k_xid == rp->c_key.k_xid &&

	    key->c_key.k_csum != rp->c_key.k_csum)

	    key->c_key.k_csum != rp->c_key.k_csum) {

		++nn->payload_misses;

		trace_nfsd_drc_mismatch(nn, key, rp);

	}



	return memcmp(&key->c_key, &rp->c_key, sizeof(key->c_key));

}
@@ -377,15 +378,22 @@ out: 
	return ret;

}



/*

/**

 * nfsd_cache_lookup - Find an entry in the duplicate reply cache

 * @rqstp: Incoming Call to find

 *

 * Try to find an entry matching the current call in the cache. When none

 * is found, we try to grab the oldest expired entry off the LRU list. If

 * a suitable one isn't there, then drop the cache_lock and allocate a

 * new one, then search again in case one got inserted while this thread

 * didn't hold the lock.

 *

 * Return values:

 *   %RC_DOIT: Process the request normally

 *   %RC_REPLY: Reply from cache

 *   %RC_DROPIT: Do not process the request further

 */

int

nfsd_cache_lookup(struct svc_rqst *rqstp)

int nfsd_cache_lookup(struct svc_rqst *rqstp)

{

	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

	struct svc_cacherep	*rp, *found;
@@ -399,7 +407,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) 
	rqstp->rq_cacherep = NULL;

	if (type == RC_NOCACHE) {

		nfsdstats.rcnocache++;

		return rtn;

		goto out;

	}



	csum = nfsd_cache_csum(rqstp);
@@ -409,10 +417,8 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) 
	 * preallocate an entry.

	 */

	rp = nfsd_reply_cache_alloc(rqstp, csum, nn);

	if (!rp) {

		dprintk("nfsd: unable to allocate DRC entry!\n");

		return rtn;

	}

	if (!rp)

		goto out;



	spin_lock(&b->cache_lock);

	found = nfsd_cache_insert(b, rp, nn);
@@ -431,8 +437,10 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) 


	/* go ahead and prune the cache */

	prune_bucket(b, nn);

 out:



out_unlock:

	spin_unlock(&b->cache_lock);

out:

	return rtn;



found_entry:
@@ -442,13 +450,13 @@ found_entry: 


	/* Request being processed */

	if (rp->c_state == RC_INPROG)

		goto out;

		goto out_trace;



	/* From the hall of fame of impractical attacks:

	 * Is this a user who tries to snoop on the cache? */

	rtn = RC_DOIT;

	if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && rp->c_secure)

		goto out;

		goto out_trace;



	/* Compose RPC reply header */

	switch (rp->c_type) {
@@ -460,7 +468,7 @@ found_entry: 
		break;

	case RC_REPLBUFF:

		if (!nfsd_cache_append(rqstp, &rp->c_replvec))

			goto out;	/* should not happen */

			goto out_unlock; /* should not happen */

		rtn = RC_REPLY;

		break;

	default:
@@ -468,13 +476,19 @@ found_entry: 
		nfsd_reply_cache_free_locked(b, rp, nn);

	}



	goto out;

out_trace:

	trace_nfsd_drc_found(nn, rqstp, rtn);

	goto out_unlock;

}



/*

 * Update a cache entry. This is called from nfsd_dispatch when

 * the procedure has been executed and the complete reply is in

 * rqstp->rq_res.

/**

 * nfsd_cache_update - Update an entry in the duplicate reply cache.

 * @rqstp: svc_rqst with a finished Reply

 * @cachetype: which cache to update

 * @statp: Reply's status code

 *

 * This is called from nfsd_dispatch when the procedure has been

 * executed and the complete reply is in rqstp->rq_res.

 *

 * We're copying around data here rather than swapping buffers because

 * the toplevel loop requires max-sized buffers, which would be a waste
@@ -487,8 +501,7 @@ found_entry: 
 * nfsd failed to encode a reply that otherwise would have been cached.

 * In this case, nfsd_cache_update is called with statp == NULL.

 */

void

nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)

void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)

{

	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

	struct svc_cacherep *rp = rqstp->rq_cacherep;

fs/nfsd/trace.h

+59 −0
Original line number Diff line number Diff line
@@ -432,6 +432,65 @@ TRACE_EVENT(nfsd_file_fsnotify_handle_event, 
			__entry->nlink, __entry->mode, __entry->mask)

);



#include "cache.h"



TRACE_DEFINE_ENUM(RC_DROPIT);

TRACE_DEFINE_ENUM(RC_REPLY);

TRACE_DEFINE_ENUM(RC_DOIT);



#define show_drc_retval(x)						\

	__print_symbolic(x,						\

		{ RC_DROPIT, "DROPIT" },				\

		{ RC_REPLY, "REPLY" },					\

		{ RC_DOIT, "DOIT" })



TRACE_EVENT(nfsd_drc_found,

	TP_PROTO(

		const struct nfsd_net *nn,

		const struct svc_rqst *rqstp,

		int result

	),

	TP_ARGS(nn, rqstp, result),

	TP_STRUCT__entry(

		__field(unsigned long long, boot_time)

		__field(unsigned long, result)

		__field(u32, xid)

	),

	TP_fast_assign(

		__entry->boot_time = nn->boot_time;

		__entry->result = result;

		__entry->xid = be32_to_cpu(rqstp->rq_xid);

	),

	TP_printk("boot_time=%16llx xid=0x%08x result=%s",

		__entry->boot_time, __entry->xid,

		show_drc_retval(__entry->result))



);



TRACE_EVENT(nfsd_drc_mismatch,

	TP_PROTO(

		const struct nfsd_net *nn,

		const struct svc_cacherep *key,

		const struct svc_cacherep *rp

	),

	TP_ARGS(nn, key, rp),

	TP_STRUCT__entry(

		__field(unsigned long long, boot_time)

		__field(u32, xid)

		__field(u32, cached)

		__field(u32, ingress)

	),

	TP_fast_assign(

		__entry->boot_time = nn->boot_time;

		__entry->xid = be32_to_cpu(key->c_key.k_xid);

		__entry->cached = (__force u32)key->c_key.k_csum;

		__entry->ingress = (__force u32)rp->c_key.k_csum;

	),

	TP_printk("boot_time=%16llx xid=0x%08x cached-csum=0x%08x ingress-csum=0x%08x",

		__entry->boot_time, __entry->xid, __entry->cached,

		__entry->ingress)

);



#endif /* _NFSD_TRACE_H */



#undef TRACE_INCLUDE_PATH

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