NFSD: Clean up find_or_add_file()

Remove the call to find_file_locked() in insert_nfs4_file(). Tracing
shows that over 99% of these calls return NULL. Thus it is not worth
the expense of the extra bucket list traversal. insert_file() already
deals correctly with the case where the item is already in the hash
bucket.

Since nfsd4_file_hash_insert() is now just a wrapper around
insert_file(), move the meat of insert_file() into
nfsd4_file_hash_insert() and get rid of it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: NeilBrown <neilb@suse.de>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fb70cab..d63ce21 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4698,24 +4698,42 @@ find_file_locked(const struct svc_fh *fh, unsigned int hashval)
        return NULL;
 }
 
-static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
-                                    unsigned int hashval)
+static struct nfs4_file * find_file(struct svc_fh *fh)
 {
        struct nfs4_file *fp;
+       unsigned int hashval = file_hashval(fh);
+
+       rcu_read_lock();
+       fp = find_file_locked(fh, hashval);
+       rcu_read_unlock();
+       return fp;
+}
+
+/*
+ * On hash insertion, identify entries with the same inode but
+ * distinct filehandles. They will all be in the same hash bucket
+ * because nfs4_file's are hashed by the address in the fi_inode
+ * field.
+ */
+static noinline_for_stack struct nfs4_file *
+nfsd4_file_hash_insert(struct nfs4_file *new, const struct svc_fh *fhp)
+{
+       unsigned int hashval = file_hashval(fhp);
        struct nfs4_file *ret = NULL;
        bool alias_found = false;
+       struct nfs4_file *fi;
 
        spin_lock(&state_lock);
-       hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
+       hlist_for_each_entry_rcu(fi, &file_hashtbl[hashval], fi_hash,
                                 lockdep_is_held(&state_lock)) {
-               if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
-                       if (refcount_inc_not_zero(&fp->fi_ref))
-                               ret = fp;
-               } else if (d_inode(fh->fh_dentry) == fp->fi_inode)
-                       fp->fi_aliased = alias_found = true;
+               if (fh_match(&fi->fi_fhandle, &fhp->fh_handle)) {
+                       if (refcount_inc_not_zero(&fi->fi_ref))
+                               ret = fi;
+               } else if (d_inode(fhp->fh_dentry) == fi->fi_inode)
+                       fi->fi_aliased = alias_found = true;
        }
        if (likely(ret == NULL)) {
-               nfsd4_file_init(fh, new);
+               nfsd4_file_init(fhp, new);
                hlist_add_head_rcu(&new->fi_hash, &file_hashtbl[hashval]);
                new->fi_aliased = alias_found;
                ret = new;
@@ -4724,32 +4742,6 @@ static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
        return ret;
 }
 
-static struct nfs4_file * find_file(struct svc_fh *fh)
-{
-       struct nfs4_file *fp;
-       unsigned int hashval = file_hashval(fh);
-
-       rcu_read_lock();
-       fp = find_file_locked(fh, hashval);
-       rcu_read_unlock();
-       return fp;
-}
-
-static struct nfs4_file *
-find_or_add_file(struct nfs4_file *new, struct svc_fh *fh)
-{
-       struct nfs4_file *fp;
-       unsigned int hashval = file_hashval(fh);
-
-       rcu_read_lock();
-       fp = find_file_locked(fh, hashval);
-       rcu_read_unlock();
-       if (fp)
-               return fp;
-
-       return insert_file(new, fh, hashval);
-}
-
 static noinline_for_stack void nfsd4_file_hash_remove(struct nfs4_file *fi)
 {
        hlist_del_rcu(&fi->fi_hash);
@@ -5641,7 +5633,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
         * and check for delegations in the process of being recalled.
         * If not found, create the nfs4_file struct
         */
-       fp = find_or_add_file(open->op_file, current_fh);
+       fp = nfsd4_file_hash_insert(open->op_file, current_fh);
        if (fp != open->op_file) {
                status = nfs4_check_deleg(cl, open, &dp);
                if (status)