Break out the function that compares the rqstp and checksum against a
reply cache entry. While we're at it, track the efficacy of the checksum
over the NFS data by tracking the cases where we would have incorrectly
matched a DRC entry if we had not tracked it or the length.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfsd/nfscache.c | 44 ++++++++++++++++++++++++++++++++++----------
1 file changed, 34 insertions(+), 10 deletions(-)
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 62c1ee1..3fba32f 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -23,9 +23,21 @@
static struct hlist_head * cache_hash;
static struct list_head lru_head;
static struct kmem_cache *drc_slab;
+
+/*
+ * Stats and other tracking of on the duplicate reply cache. All of these and
+ * the "rc" fields in nfsdstats are protected by the cache_lock
+ */
+
+/* total number of entries */
static unsigned int num_drc_entries;
+
+/* max number of entries allowed in the cache */
static unsigned int max_drc_entries;
+/* cache misses due only to checksum comparison failures */
+static unsigned int payload_misses;
+
/*
* Calculate the hash index from an XID.
*/
@@ -272,6 +284,26 @@ nfsd_cache_csum(struct svc_rqst *rqstp)
return csum;
}
+static bool
+nfsd_cache_match(struct svc_rqst *rqstp, __wsum csum, struct svc_cacherep *rp)
+{
+ /* Check RPC header info first */
+ if (rqstp->rq_xid != rp->c_xid || rqstp->rq_proc != rp->c_proc ||
+ rqstp->rq_prot != rp->c_prot || rqstp->rq_vers != rp->c_vers ||
+ rqstp->rq_arg.len != rp->c_len ||
+ !rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) ||
+ rpc_get_port(svc_addr(rqstp)) != rpc_get_port((struct sockaddr *)&rp->c_addr))
+ return false;
+
+ /* compare checksum of NFS data */
+ if (csum != rp->c_csum) {
+ ++payload_misses;
+ return false;
+ }
+
+ return true;
+}
+
/*
* Search the request hash for an entry that matches the given rqstp.
* Must be called with cache_lock held. Returns the found entry or
@@ -282,18 +314,10 @@ nfsd_cache_search(struct svc_rqst *rqstp, __wsum csum)
{
struct svc_cacherep *rp;
struct hlist_head *rh;
- __be32 xid = rqstp->rq_xid;
- u32 proto = rqstp->rq_prot,
- vers = rqstp->rq_vers,
- proc = rqstp->rq_proc;
- rh = &cache_hash[request_hash(xid)];
+ rh = &cache_hash[request_hash(rqstp->rq_xid)];
hlist_for_each_entry(rp, rh, c_hash) {
- if (xid == rp->c_xid && proc == rp->c_proc &&
- proto == rp->c_prot && vers == rp->c_vers &&
- rqstp->rq_arg.len == rp->c_len && csum == rp->c_csum &&
- rpc_cmp_addr(svc_addr(rqstp), (struct sockaddr *)&rp->c_addr) &&
- rpc_get_port(svc_addr(rqstp)) == rpc_get_port((struct sockaddr *)&rp->c_addr))
+ if (nfsd_cache_match(rqstp, csum, rp))
return rp;
}
return NULL;
--
1.7.11.7
--
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