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: kbuild test robot <lkp@xxxxxxxxx>
[ cel: force typecast for display of checksum values ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/nfscache.c | 57 +++++++++++++++++++++++++++++++-------------------
fs/nfsd/trace.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 94 insertions(+), 22 deletions(-)
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 96352ab7bd81..945d2f5e760e 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -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 @@ nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key,
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 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
/* 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 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
* 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;
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 78c574251c60..371dc198d28e 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -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
