Merge tag 'nfsd-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

Pull more nfsd updates from Chuck Lever:

 - filecache code clean-ups

* tag 'nfsd-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  nfsd: rework hashtable handling in nfsd_do_file_acquire
  nfsd: fix nfsd_file_unhash_and_dispose

1 files changed, 29 insertions, 59 deletions

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index d5c57360b418..29a62db155fb 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -405,22 +405,15 @@ nfsd_file_unhash(struct nfsd_file *nf)
 	return false;
 }
 
-/*
- * Return true if the file was unhashed.
- */
-static bool
+static void
 nfsd_file_unhash_and_dispose(struct nfsd_file *nf, struct list_head *dispose)
 {
 	trace_nfsd_file_unhash_and_dispose(nf);
-	if (!nfsd_file_unhash(nf))
-		return false;
-	/* keep final reference for nfsd_file_lru_dispose */
-	if (refcount_dec_not_one(&nf->nf_ref))
-		return true;
-
-	nfsd_file_lru_remove(nf);
-	list_add(&nf->nf_lru, dispose);
-	return true;
+	if (nfsd_file_unhash(nf)) {
+		/* caller must call nfsd_file_dispose_list() later */
+		nfsd_file_lru_remove(nf);
+		list_add(&nf->nf_lru, dispose);
+	}
 }
 
 static void
@@ -562,8 +555,6 @@ nfsd_file_dispose_list_delayed(struct list_head *dispose)
  * @lock: LRU list lock (unused)
  * @arg: dispose list
  *
- * Note this can deadlock with nfsd_file_cache_purge.
- *
  * Return values:
  *   %LRU_REMOVED: @item was removed from the LRU
  *   %LRU_ROTATE: @item is to be moved to the LRU tail
@@ -748,8 +739,6 @@ nfsd_file_close_inode(struct inode *inode)
  *
  * Walk the LRU list and close any entries that have not been used since
  * the last scan.
- *
- * Note this can deadlock with nfsd_file_cache_purge.
  */
 static void
 nfsd_file_delayed_close(struct work_struct *work)
@@ -891,16 +880,12 @@ out_err:
 	goto out;
 }
 
-/*
- * Note this can deadlock with nfsd_file_lru_cb.
- */
 static void
 __nfsd_file_cache_purge(struct net *net)
 {
 	struct rhashtable_iter iter;
 	struct nfsd_file *nf;
 	LIST_HEAD(dispose);
-	bool del;
 
 	rhashtable_walk_enter(&nfsd_file_rhash_tbl, &iter);
 	do {
@@ -910,14 +895,7 @@ __nfsd_file_cache_purge(struct net *net)
 		while (!IS_ERR_OR_NULL(nf)) {
 			if (net && nf->nf_net != net)
 				continue;
-			del = nfsd_file_unhash_and_dispose(nf, &dispose);
-
-			/*
-			 * Deadlock detected! Something marked this entry as
-			 * unhased, but hasn't removed it from the hash list.
-			 */
-			WARN_ON_ONCE(!del);
-
+			nfsd_file_unhash_and_dispose(nf, &dispose);
 			nf = rhashtable_walk_next(&iter);
 		}
 
@@ -1064,9 +1042,10 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		.need	= may_flags & NFSD_FILE_MAY_MASK,
 		.net	= SVC_NET(rqstp),
 	};
-	struct nfsd_file *nf, *new;
-	bool retry = true;
+	bool open_retry = true;
+	struct nfsd_file *nf;
 	__be32 status;
+	int ret;
 
 	status = fh_verify(rqstp, fhp, S_IFREG,
 				may_flags|NFSD_MAY_OWNER_OVERRIDE);
@@ -1076,35 +1055,33 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	key.cred = get_current_cred();
 
 retry:
-	/* Avoid allocation if the item is already in cache */
-	nf = rhashtable_lookup_fast(&nfsd_file_rhash_tbl, &key,
-				    nfsd_file_rhash_params);
+	rcu_read_lock();
+	nf = rhashtable_lookup(&nfsd_file_rhash_tbl, &key,
+			       nfsd_file_rhash_params);
 	if (nf)
 		nf = nfsd_file_get(nf);
+	rcu_read_unlock();
 	if (nf)
 		goto wait_for_construction;
 
-	new = nfsd_file_alloc(&key, may_flags);
-	if (!new) {
+	nf = nfsd_file_alloc(&key, may_flags);
+	if (!nf) {
 		status = nfserr_jukebox;
 		goto out_status;
 	}
 
-	nf = rhashtable_lookup_get_insert_key(&nfsd_file_rhash_tbl,
-					      &key, &new->nf_rhash,
-					      nfsd_file_rhash_params);
-	if (!nf) {
-		nf = new;
-		goto open_file;
-	}
-	if (IS_ERR(nf))
-		goto insert_err;
-	nf = nfsd_file_get(nf);
-	if (nf == NULL) {
-		nf = new;
+	ret = rhashtable_lookup_insert_key(&nfsd_file_rhash_tbl,
+					   &key, &nf->nf_rhash,
+					   nfsd_file_rhash_params);
+	if (likely(ret == 0))
 		goto open_file;
-	}
-	nfsd_file_slab_free(&new->nf_rcu);
+
+	nfsd_file_slab_free(&nf->nf_rcu);
+	if (ret == -EEXIST)
+		goto retry;
+	trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, ret);
+	status = nfserr_jukebox;
+	goto out_status;
 
 wait_for_construction:
 	wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
@@ -1112,11 +1089,11 @@ wait_for_construction:
 	/* Did construction of this file fail? */
 	if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
 		trace_nfsd_file_cons_err(rqstp, key.inode, may_flags, nf);
-		if (!retry) {
+		if (!open_retry) {
 			status = nfserr_jukebox;
 			goto out;
 		}
-		retry = false;
+		open_retry = false;
 		nfsd_file_put_noref(nf);
 		goto retry;
 	}
@@ -1164,13 +1141,6 @@ open_file:
 	smp_mb__after_atomic();
 	wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
 	goto out;
-
-insert_err:
-	nfsd_file_slab_free(&new->nf_rcu);
-	trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, PTR_ERR(nf));
-	nf = NULL;
-	status = nfserr_jukebox;
-	goto out_status;
 }
 
 /**