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Commit 9dc56143 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
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nfsd: break out comparator into separate function 



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: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 0b9ea37f

fs/nfsd/nfscache.c

+35 −11
Original line number Diff line number Diff line
@@ -23,9 +23,21 @@ 
static struct hlist_head *	cache_hash;

static struct list_head 	lru_head;

static struct kmem_cache	*drc_slab;

static unsigned int		num_drc_entries;



/* max number of entries allowed in the cache */

static unsigned int		max_drc_entries;



/*

 * 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;



/* cache misses due only to checksum comparison failures */

static unsigned int		payload_misses;



/*

 * Calculate the hash index from an XID.

 */
@@ -273,6 +285,26 @@ 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
@@ -283,18 +315,10 @@ 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;