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: kbuild test robot <lkp@intel.com> [ cel: force typecast for display of checksum values ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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Chuck Lever
parent
d88ff9587b
commit
0b175b1864
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@ -20,8 +20,7 @@
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#include "nfsd.h"
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#include "cache.h"
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#define NFSDDBG_FACILITY NFSDDBG_REPCACHE
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#include "trace.h"
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/*
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* We use this value to determine the number of hash buckets from the max
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@ -323,8 +322,10 @@ nfsd_cache_key_cmp(const struct svc_cacherep *key,
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const struct svc_cacherep *rp, struct nfsd_net *nn)
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{
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if (key->c_key.k_xid == rp->c_key.k_xid &&
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key->c_key.k_csum != rp->c_key.k_csum)
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key->c_key.k_csum != rp->c_key.k_csum) {
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++nn->payload_misses;
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trace_nfsd_drc_mismatch(nn, key, rp);
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}
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return memcmp(&key->c_key, &rp->c_key, sizeof(key->c_key));
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}
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@ -377,15 +378,22 @@ out:
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return ret;
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}
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/*
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/**
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* nfsd_cache_lookup - Find an entry in the duplicate reply cache
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* @rqstp: Incoming Call to find
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*
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* Try to find an entry matching the current call in the cache. When none
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* is found, we try to grab the oldest expired entry off the LRU list. If
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* a suitable one isn't there, then drop the cache_lock and allocate a
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* new one, then search again in case one got inserted while this thread
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* didn't hold the lock.
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*
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* Return values:
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* %RC_DOIT: Process the request normally
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* %RC_REPLY: Reply from cache
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* %RC_DROPIT: Do not process the request further
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*/
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int
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nfsd_cache_lookup(struct svc_rqst *rqstp)
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int nfsd_cache_lookup(struct svc_rqst *rqstp)
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{
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struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
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struct svc_cacherep *rp, *found;
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@ -399,7 +407,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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rqstp->rq_cacherep = NULL;
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if (type == RC_NOCACHE) {
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nfsdstats.rcnocache++;
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return rtn;
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goto out;
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}
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csum = nfsd_cache_csum(rqstp);
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@ -409,10 +417,8 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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* preallocate an entry.
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*/
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rp = nfsd_reply_cache_alloc(rqstp, csum, nn);
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if (!rp) {
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dprintk("nfsd: unable to allocate DRC entry!\n");
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return rtn;
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}
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if (!rp)
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goto out;
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spin_lock(&b->cache_lock);
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found = nfsd_cache_insert(b, rp, nn);
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@ -431,8 +437,10 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
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/* go ahead and prune the cache */
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prune_bucket(b, nn);
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out:
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out_unlock:
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spin_unlock(&b->cache_lock);
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out:
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return rtn;
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found_entry:
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@ -442,13 +450,13 @@ found_entry:
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/* Request being processed */
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if (rp->c_state == RC_INPROG)
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goto out;
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goto out_trace;
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/* From the hall of fame of impractical attacks:
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* Is this a user who tries to snoop on the cache? */
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rtn = RC_DOIT;
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if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && rp->c_secure)
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goto out;
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goto out_trace;
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/* Compose RPC reply header */
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switch (rp->c_type) {
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@ -460,7 +468,7 @@ found_entry:
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break;
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case RC_REPLBUFF:
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if (!nfsd_cache_append(rqstp, &rp->c_replvec))
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goto out; /* should not happen */
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goto out_unlock; /* should not happen */
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rtn = RC_REPLY;
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break;
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default:
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@ -468,13 +476,19 @@ found_entry:
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nfsd_reply_cache_free_locked(b, rp, nn);
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}
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goto out;
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out_trace:
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trace_nfsd_drc_found(nn, rqstp, rtn);
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goto out_unlock;
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}
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/*
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* Update a cache entry. This is called from nfsd_dispatch when
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* the procedure has been executed and the complete reply is in
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* rqstp->rq_res.
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/**
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* nfsd_cache_update - Update an entry in the duplicate reply cache.
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* @rqstp: svc_rqst with a finished Reply
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* @cachetype: which cache to update
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* @statp: Reply's status code
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*
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* This is called from nfsd_dispatch when the procedure has been
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* executed and the complete reply is in rqstp->rq_res.
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*
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* We're copying around data here rather than swapping buffers because
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* the toplevel loop requires max-sized buffers, which would be a waste
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@ -487,8 +501,7 @@ found_entry:
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* nfsd failed to encode a reply that otherwise would have been cached.
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* In this case, nfsd_cache_update is called with statp == NULL.
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*/
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void
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nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
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void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
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{
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struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
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struct svc_cacherep *rp = rqstp->rq_cacherep;
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@ -432,6 +432,65 @@ TRACE_EVENT(nfsd_file_fsnotify_handle_event,
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__entry->nlink, __entry->mode, __entry->mask)
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);
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#include "cache.h"
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TRACE_DEFINE_ENUM(RC_DROPIT);
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TRACE_DEFINE_ENUM(RC_REPLY);
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TRACE_DEFINE_ENUM(RC_DOIT);
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#define show_drc_retval(x) \
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__print_symbolic(x, \
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{ RC_DROPIT, "DROPIT" }, \
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{ RC_REPLY, "REPLY" }, \
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{ RC_DOIT, "DOIT" })
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TRACE_EVENT(nfsd_drc_found,
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TP_PROTO(
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const struct nfsd_net *nn,
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const struct svc_rqst *rqstp,
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int result
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),
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TP_ARGS(nn, rqstp, result),
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TP_STRUCT__entry(
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__field(unsigned long long, boot_time)
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__field(unsigned long, result)
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__field(u32, xid)
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),
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TP_fast_assign(
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__entry->boot_time = nn->boot_time;
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__entry->result = result;
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__entry->xid = be32_to_cpu(rqstp->rq_xid);
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),
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TP_printk("boot_time=%16llx xid=0x%08x result=%s",
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__entry->boot_time, __entry->xid,
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show_drc_retval(__entry->result))
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);
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TRACE_EVENT(nfsd_drc_mismatch,
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TP_PROTO(
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const struct nfsd_net *nn,
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const struct svc_cacherep *key,
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const struct svc_cacherep *rp
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),
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TP_ARGS(nn, key, rp),
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TP_STRUCT__entry(
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__field(unsigned long long, boot_time)
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__field(u32, xid)
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__field(u32, cached)
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__field(u32, ingress)
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),
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TP_fast_assign(
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__entry->boot_time = nn->boot_time;
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__entry->xid = be32_to_cpu(key->c_key.k_xid);
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__entry->cached = (__force u32)key->c_key.k_csum;
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__entry->ingress = (__force u32)rp->c_key.k_csum;
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),
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TP_printk("boot_time=%16llx xid=0x%08x cached-csum=0x%08x ingress-csum=0x%08x",
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__entry->boot_time, __entry->xid, __entry->cached,
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__entry->ingress)
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);
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#endif /* _NFSD_TRACE_H */
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#undef TRACE_INCLUDE_PATH
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