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From:   Trond Myklebust <trondmy@gmail.com>
To:     "J. Bruce Fields" <bfields@redhat.com>
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH 5/8] nfsd: export upcalls must not return ESTALE when mountd is down
Date:   Sun,  1 Mar 2020 18:21:42 -0500
Message-Id: <20200301232145.1465430-6-trond.myklebust@hammerspace.com>
In-Reply-To: <20200301232145.1465430-5-trond.myklebust@hammerspace.com>
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 <20200301232145.1465430-3-trond.myklebust@hammerspace.com>
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 <20200301232145.1465430-5-trond.myklebust@hammerspace.com>
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If the rpc.mountd daemon goes down, then that should not cause all
exports to start failing with ESTALE errors. Let's explicitly
distinguish between the cache upcall cases that need to time out,
and those that do not.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dns_resolve.c              | 11 ++++---
 fs/nfsd/export.c                  | 12 +++++++
 fs/nfsd/nfs4idmap.c               | 14 ++++++++
 include/linux/sunrpc/cache.h      |  3 ++
 net/sunrpc/auth_gss/svcauth_gss.c | 12 +++++++
 net/sunrpc/cache.c                | 53 +++++++++++++++----------------
 net/sunrpc/svcauth_unix.c         | 12 +++++++
 7 files changed, 85 insertions(+), 32 deletions(-)

diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index 89bd5581f317..963800037609 100644
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -152,12 +152,13 @@ static int nfs_dns_upcall(struct cache_detail *cd,
 		struct cache_head *ch)
 {
 	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
-	int ret;
 
-	ret = nfs_cache_upcall(cd, key->hostname);
-	if (ret)
-		ret = sunrpc_cache_pipe_upcall(cd, ch);
-	return ret;
+	if (test_and_set_bit(CACHE_PENDING, &ch->flags))
+		return 0;
+	if (!nfs_cache_upcall(cd, key->hostname))
+		return 0;
+	clear_bit(CACHE_PENDING, &ch->flags);
+	return sunrpc_cache_pipe_upcall_timeout(cd, ch);
 }
 
 static int nfs_dns_match(struct cache_head *ca,
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 6e6cbeb7ac2b..cb777fe82988 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -51,6 +51,11 @@ static void expkey_put(struct kref *ref)
 	kfree_rcu(key, ek_rcu);
 }
 
+static int expkey_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall(cd, h);
+}
+
 static void expkey_request(struct cache_detail *cd,
 			   struct cache_head *h,
 			   char **bpp, int *blen)
@@ -254,6 +259,7 @@ static const struct cache_detail svc_expkey_cache_template = {
 	.hash_size	= EXPKEY_HASHMAX,
 	.name		= "nfsd.fh",
 	.cache_put	= expkey_put,
+	.cache_upcall	= expkey_upcall,
 	.cache_request	= expkey_request,
 	.cache_parse	= expkey_parse,
 	.cache_show	= expkey_show,
@@ -335,6 +341,11 @@ static void svc_export_put(struct kref *ref)
 	kfree_rcu(exp, ex_rcu);
 }
 
+static int svc_export_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall(cd, h);
+}
+
 static void svc_export_request(struct cache_detail *cd,
 			       struct cache_head *h,
 			       char **bpp, int *blen)
@@ -774,6 +785,7 @@ static const struct cache_detail svc_export_cache_template = {
 	.hash_size	= EXPORT_HASHMAX,
 	.name		= "nfsd.export",
 	.cache_put	= svc_export_put,
+	.cache_upcall	= svc_export_upcall,
 	.cache_request	= svc_export_request,
 	.cache_parse	= svc_export_parse,
 	.cache_show	= svc_export_show,
diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c
index d1f285245af8..9460be8a8321 100644
--- a/fs/nfsd/nfs4idmap.c
+++ b/fs/nfsd/nfs4idmap.c
@@ -122,6 +122,12 @@ idtoname_hash(struct ent *ent)
 	return hash;
 }
 
+static int
+idtoname_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall_timeout(cd, h);
+}
+
 static void
 idtoname_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
     int *blen)
@@ -184,6 +190,7 @@ static const struct cache_detail idtoname_cache_template = {
 	.hash_size	= ENT_HASHMAX,
 	.name		= "nfs4.idtoname",
 	.cache_put	= ent_put,
+	.cache_upcall	= idtoname_upcall,
 	.cache_request	= idtoname_request,
 	.cache_parse	= idtoname_parse,
 	.cache_show	= idtoname_show,
@@ -295,6 +302,12 @@ nametoid_hash(struct ent *ent)
 	return hash_str(ent->name, ENT_HASHBITS);
 }
 
+static int
+nametoid_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall_timeout(cd, h);
+}
+
 static void
 nametoid_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
     int *blen)
@@ -347,6 +360,7 @@ static const struct cache_detail nametoid_cache_template = {
 	.hash_size	= ENT_HASHMAX,
 	.name		= "nfs4.nametoid",
 	.cache_put	= ent_put,
+	.cache_upcall	= nametoid_upcall,
 	.cache_request	= nametoid_request,
 	.cache_parse	= nametoid_parse,
 	.cache_show	= nametoid_show,
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 0f64de7caa39..656882a50991 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -179,6 +179,9 @@ sunrpc_cache_update(struct cache_detail *detail,
 
 extern int
 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
+extern int
+sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
+				 struct cache_head *h);
 
 
 extern void cache_clean_deferred(void *owner);
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 65b67b257302..6d698bf1c16e 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -184,6 +184,11 @@ static struct cache_head *rsi_alloc(void)
 		return NULL;
 }
 
+static int rsi_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall_timeout(cd, h);
+}
+
 static void rsi_request(struct cache_detail *cd,
 		       struct cache_head *h,
 		       char **bpp, int *blen)
@@ -282,6 +287,7 @@ static const struct cache_detail rsi_cache_template = {
 	.hash_size	= RSI_HASHMAX,
 	.name           = "auth.rpcsec.init",
 	.cache_put      = rsi_put,
+	.cache_upcall	= rsi_upcall,
 	.cache_request  = rsi_request,
 	.cache_parse    = rsi_parse,
 	.match		= rsi_match,
@@ -428,6 +434,11 @@ rsc_alloc(void)
 		return NULL;
 }
 
+static int rsc_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return -EINVAL;
+}
+
 static int rsc_parse(struct cache_detail *cd,
 		     char *mesg, int mlen)
 {
@@ -554,6 +565,7 @@ static const struct cache_detail rsc_cache_template = {
 	.hash_size	= RSC_HASHMAX,
 	.name		= "auth.rpcsec.context",
 	.cache_put	= rsc_put,
+	.cache_upcall	= rsc_upcall,
 	.cache_parse	= rsc_parse,
 	.match		= rsc_match,
 	.init		= rsc_init,
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index bd843a81afa0..5e14513603cb 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -38,7 +38,6 @@
 
 static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
 static void cache_revisit_request(struct cache_head *item);
-static bool cache_listeners_exist(struct cache_detail *detail);
 
 static void cache_init(struct cache_head *h, struct cache_detail *detail)
 {
@@ -224,13 +223,6 @@ struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
 }
 EXPORT_SYMBOL_GPL(sunrpc_cache_update);
 
-static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h)
-{
-	if (cd->cache_upcall)
-		return cd->cache_upcall(cd, h);
-	return sunrpc_cache_pipe_upcall(cd, h);
-}
-
 static inline int cache_is_valid(struct cache_head *h)
 {
 	if (!test_bit(CACHE_VALID, &h->flags))
@@ -303,17 +295,14 @@ int cache_check(struct cache_detail *detail,
 		   (h->expiry_time != 0 && age > refresh_age/2)) {
 		dprintk("RPC:       Want update, refage=%lld, age=%lld\n",
 				refresh_age, age);
-		if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
-			switch (cache_make_upcall(detail, h)) {
-			case -EINVAL:
-				rv = try_to_negate_entry(detail, h);
-				break;
-			case -EAGAIN:
-				cache_fresh_unlocked(h, detail);
-				break;
-			}
-		} else if (!cache_listeners_exist(detail))
+		switch (detail->cache_upcall(detail, h)) {
+		case -EINVAL:
 			rv = try_to_negate_entry(detail, h);
+			break;
+		case -EAGAIN:
+			cache_fresh_unlocked(h, detail);
+			break;
+		}
 	}
 
 	if (rv == -EAGAIN) {
@@ -1195,20 +1184,12 @@ static bool cache_listeners_exist(struct cache_detail *detail)
  *
  * Each request is at most one page long.
  */
-int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
+static int cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
 {
-
 	char *buf;
 	struct cache_request *crq;
 	int ret = 0;
 
-	if (!detail->cache_request)
-		return -EINVAL;
-
-	if (!cache_listeners_exist(detail)) {
-		warn_no_listener(detail);
-		return -EINVAL;
-	}
 	if (test_bit(CACHE_CLEANED, &h->flags))
 		/* Too late to make an upcall */
 		return -EAGAIN;
@@ -1242,8 +1223,26 @@ int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
 	}
 	return ret;
 }
+
+int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h)
+{
+	if (test_and_set_bit(CACHE_PENDING, &h->flags))
+		return 0;
+	return cache_pipe_upcall(detail, h);
+}
 EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall);
 
+int sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
+				     struct cache_head *h)
+{
+	if (!cache_listeners_exist(detail)) {
+		warn_no_listener(detail);
+		return -EINVAL;
+	}
+	return sunrpc_cache_pipe_upcall(detail, h);
+}
+EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall_timeout);
+
 /*
  * parse a message from user-space and pass it
  * to an appropriate cache
diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 04aa80a2d752..6c8f802c4261 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -148,6 +148,11 @@ static struct cache_head *ip_map_alloc(void)
 		return NULL;
 }
 
+static int ip_map_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall(cd, h);
+}
+
 static void ip_map_request(struct cache_detail *cd,
 				  struct cache_head *h,
 				  char **bpp, int *blen)
@@ -467,6 +472,11 @@ static struct cache_head *unix_gid_alloc(void)
 		return NULL;
 }
 
+static int unix_gid_upcall(struct cache_detail *cd, struct cache_head *h)
+{
+	return sunrpc_cache_pipe_upcall_timeout(cd, h);
+}
+
 static void unix_gid_request(struct cache_detail *cd,
 			     struct cache_head *h,
 			     char **bpp, int *blen)
@@ -584,6 +594,7 @@ static const struct cache_detail unix_gid_cache_template = {
 	.hash_size	= GID_HASHMAX,
 	.name		= "auth.unix.gid",
 	.cache_put	= unix_gid_put,
+	.cache_upcall	= unix_gid_upcall,
 	.cache_request	= unix_gid_request,
 	.cache_parse	= unix_gid_parse,
 	.cache_show	= unix_gid_show,
@@ -881,6 +892,7 @@ static const struct cache_detail ip_map_cache_template = {
 	.hash_size	= IP_HASHMAX,
 	.name		= "auth.unix.ip",
 	.cache_put	= ip_map_put,
+	.cache_upcall	= ip_map_upcall,
 	.cache_request	= ip_map_request,
 	.cache_parse	= ip_map_parse,
 	.cache_show	= ip_map_show,
-- 
2.24.1