Merge tag 'nfs-for-6.16-1' of git://git.linux-nfs.org/projects/anna/linux-nfs

Pull NFS clent updates from Anna Schumaker:
 "New Features:

   - Implement the Sunrpc rfc2203 rpcsec_gss sequence number cache

   - Add support for FALLOC_FL_ZERO_RANGE on NFS v4.2

   - Add a localio sysfs attribute

  Stable Fixes:

   - Fix double-unlock bug in nfs_return_empty_folio()

   - Don't check for OPEN feature support in v4.1

   - Always probe for LOCALIO support asynchronously

   - Prevent hang on NFS mounts with xprtsec=[m]tls

  Other Bugfixes:

   - xattr handlers should check for absent nfs filehandles

   - Fix setattr caching of TIME_[MODIFY|ACCESS]_SET when timestamps are
     delegated

   - Fix listxattr to return selinux security labels

   - Connect to NFSv3 DS using TLS if MDS connection uses TLS

   - Clear SB_RDONLY before getting a superblock, and ignore when
     remounting

   - Fix incorrect handling of NFS error codes in nfs4_do_mkdir()

   - Various nfs_localio fixes from Neil Brown that include fixing an
     rcu compilation error found by older gcc versions.

   - Update stats on flexfiles pNFS DSes when receiving NFS4ERR_DELAY

  Cleanups:

   - Add a refcount tracker for struct net in the nfs_client

   - Allow FREE_STATEID to clean up delegations

   - Always set NLINK even if the server doesn't support it

   - Cleanups to the NFS folio writeback code

   - Remove dead code from xs_tcp_tls_setup_socket()"

* tag 'nfs-for-6.16-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (30 commits)
  flexfiles/pNFS: update stats on NFS4ERR_DELAY for v4.1 DSes
  nfs_localio: change nfsd_file_put_local() to take a pointer to __rcu pointer
  nfs_localio: protect race between nfs_uuid_put() and nfs_close_local_fh()
  nfs_localio: duplicate nfs_close_local_fh()
  nfs_localio: simplify interface to nfsd for getting nfsd_file
  nfs_localio: always hold nfsd net ref with nfsd_file ref
  nfs_localio: use cmpxchg() to install new nfs_file_localio
  SUNRPC: Remove dead code from xs_tcp_tls_setup_socket()
  SUNRPC: Prevent hang on NFS mount with xprtsec=[m]tls
  nfs: fix incorrect handling of large-number NFS errors in nfs4_do_mkdir()
  nfs: ignore SB_RDONLY when remounting nfs
  nfs: clear SB_RDONLY before getting superblock
  NFS: always probe for LOCALIO support asynchronously
  pnfs/flexfiles: connect to NFSv3 DS using TLS if MDS connection uses TLS
  NFS: add localio to sysfs
  nfs: use writeback_iter directly
  nfs: refactor nfs_do_writepage
  nfs: don't return AOP_WRITEPAGE_ACTIVATE from nfs_do_writepage
  nfs: fold nfs_page_async_flush into nfs_do_writepage
  NFSv4: Always set NLINK even if the server doesn't support it
  ...

3 files changed, 83 insertions, 22 deletions

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index ab85e6a2454f..e108b6c705b4 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -378,15 +378,41 @@ nfsd_file_put(struct nfsd_file *nf)
  * the reference of the nfsd_file.
  */
 struct net *
-nfsd_file_put_local(struct nfsd_file *nf)
+nfsd_file_put_local(struct nfsd_file __rcu **pnf)
 {
-	struct net *net = nf->nf_net;
+	struct nfsd_file *nf;
+	struct net *net = NULL;
 
-	nfsd_file_put(nf);
+	nf = unrcu_pointer(xchg(pnf, NULL));
+	if (nf) {
+		net = nf->nf_net;
+		nfsd_file_put(nf);
+	}
 	return net;
 }
 
 /**
+ * nfsd_file_get_local - get nfsd_file reference and reference to net
+ * @nf: nfsd_file of which to put the reference
+ *
+ * Get reference to both the nfsd_file and nf->nf_net.
+ */
+struct nfsd_file *
+nfsd_file_get_local(struct nfsd_file *nf)
+{
+	struct net *net = nf->nf_net;
+
+	if (nfsd_net_try_get(net)) {
+		nf = nfsd_file_get(nf);
+		if (!nf)
+			nfsd_net_put(net);
+	} else {
+		nf = NULL;
+	}
+	return nf;
+}
+
+/**
  * nfsd_file_file - get the backing file of an nfsd_file
  * @nf: nfsd_file of which to access the backing file.
  *
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index 5865f9c72712..722b26c71e45 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -62,7 +62,8 @@ void nfsd_file_cache_shutdown(void);
 int nfsd_file_cache_start_net(struct net *net);
 void nfsd_file_cache_shutdown_net(struct net *net);
 void nfsd_file_put(struct nfsd_file *nf);
-struct net *nfsd_file_put_local(struct nfsd_file *nf);
+struct net *nfsd_file_put_local(struct nfsd_file __rcu **nf);
+struct nfsd_file *nfsd_file_get_local(struct nfsd_file *nf);
 struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
 struct file *nfsd_file_file(struct nfsd_file *nf);
 void nfsd_file_close_inode_sync(struct inode *inode);
diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c
index 238647fa379e..80d9ff6608a7 100644
--- a/fs/nfsd/localio.c
+++ b/fs/nfsd/localio.c
@@ -24,21 +24,6 @@
 #include "filecache.h"
 #include "cache.h"
 
-static const struct nfsd_localio_operations nfsd_localio_ops = {
-	.nfsd_net_try_get  = nfsd_net_try_get,
-	.nfsd_net_put  = nfsd_net_put,
-	.nfsd_open_local_fh = nfsd_open_local_fh,
-	.nfsd_file_put_local = nfsd_file_put_local,
-	.nfsd_file_get = nfsd_file_get,
-	.nfsd_file_put = nfsd_file_put,
-	.nfsd_file_file = nfsd_file_file,
-};
-
-void nfsd_localio_ops_init(void)
-{
-	nfs_to = &nfsd_localio_ops;
-}
-
 /**
  * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to nfsd_file
  *
@@ -47,6 +32,7 @@ void nfsd_localio_ops_init(void)
  * @rpc_clnt: rpc_clnt that the client established
  * @cred: cred that the client established
  * @nfs_fh: filehandle to lookup
+ * @nfp: place to find the nfsd_file, or store it if it was non-NULL
  * @fmode: fmode_t to use for open
  *
  * This function maps a local fh to a path on a local filesystem.
@@ -57,10 +43,11 @@ void nfsd_localio_ops_init(void)
  * set. Caller (NFS client) is responsible for calling nfsd_net_put and
  * nfsd_file_put (via nfs_to_nfsd_file_put_local).
  */
-struct nfsd_file *
+static struct nfsd_file *
 nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
 		   struct rpc_clnt *rpc_clnt, const struct cred *cred,
-		   const struct nfs_fh *nfs_fh, const fmode_t fmode)
+		   const struct nfs_fh *nfs_fh, struct nfsd_file __rcu **pnf,
+		   const fmode_t fmode)
 {
 	int mayflags = NFSD_MAY_LOCALIO;
 	struct svc_cred rq_cred;
@@ -71,6 +58,15 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
 	if (nfs_fh->size > NFS4_FHSIZE)
 		return ERR_PTR(-EINVAL);
 
+	if (!nfsd_net_try_get(net))
+		return ERR_PTR(-ENXIO);
+
+	rcu_read_lock();
+	localio = nfsd_file_get(rcu_dereference(*pnf));
+	rcu_read_unlock();
+	if (localio)
+		return localio;
+
 	/* nfs_fh -> svc_fh */
 	fh_init(&fh, NFS4_FHSIZE);
 	fh.fh_handle.fh_size = nfs_fh->size;
@@ -92,9 +88,47 @@ nfsd_open_local_fh(struct net *net, struct auth_domain *dom,
 	if (rq_cred.cr_group_info)
 		put_group_info(rq_cred.cr_group_info);
 
+	if (!IS_ERR(localio)) {
+		struct nfsd_file *new;
+		if (!nfsd_net_try_get(net)) {
+			nfsd_file_put(localio);
+			nfsd_net_put(net);
+			return ERR_PTR(-ENXIO);
+		}
+		nfsd_file_get(localio);
+	again:
+		new = unrcu_pointer(cmpxchg(pnf, NULL, RCU_INITIALIZER(localio)));
+		if (new) {
+			/* Some other thread installed an nfsd_file */
+			if (nfsd_file_get(new) == NULL)
+				goto again;
+			/*
+			 * Drop the ref we were going to install and the
+			 * one we were going to return.
+			 */
+			nfsd_file_put(localio);
+			nfsd_file_put(localio);
+			localio = new;
+		}
+	} else
+		nfsd_net_put(net);
+
 	return localio;
 }
-EXPORT_SYMBOL_GPL(nfsd_open_local_fh);
+
+static const struct nfsd_localio_operations nfsd_localio_ops = {
+	.nfsd_net_try_get  = nfsd_net_try_get,
+	.nfsd_net_put  = nfsd_net_put,
+	.nfsd_open_local_fh = nfsd_open_local_fh,
+	.nfsd_file_put_local = nfsd_file_put_local,
+	.nfsd_file_get_local = nfsd_file_get_local,
+	.nfsd_file_file = nfsd_file_file,
+};
+
+void nfsd_localio_ops_init(void)
+{
+	nfs_to = &nfsd_localio_ops;
+}
 
 /*
  * UUID_IS_LOCAL XDR functions