write_foo functions are called to handle IO to files in /proc/fs/nfsd/.
They can be called at any time and so generally need locking to ensure
they don't happen at an awkward time.
Many already take nfsd_mutex and check if nfsd_serv has been set. This
ensures they only run when the server is fully configured.
write_filehandle() does *not* need locking. It interacts with the
export table which is set up when the netns is set up, so it is always
valid and it has its own locking. write_filehandle() is needed before
the nfs server is started so checking nfsd_serv would be wrong.
The remaining files which do not have any locking are
write_v4_end_grace(), write_unlock_ip(), and write_unlock_fs().
None of these make sense when the nfs server is not running and there is
evidence that write_v4_end_grace() can race with ->client_tracking_op
setup/shutdown and cause problems.
This patch adds locking to these three and ensures the "unlock"
functions abort if ->nfsd_serv is not set.
Reported-and-tested-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
fs/nfsd/nfsctl.c | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 3f3e9f6c4250..6b0cad81b5fa 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -214,13 +214,18 @@ static inline struct net *netns(struct file *file)
* returns one if one or more locks were not released
* On error: return code is negative errno value
*/
-static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
+static ssize_t __write_unlock_ip(struct file *file, char *buf, size_t size)
{
struct sockaddr_storage address;
struct sockaddr *sap = (struct sockaddr *)&address;
size_t salen = sizeof(address);
char *fo_path;
struct net *net = netns(file);
+ struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+
+ if (!nn->nfsd_serv)
+ /* There cannot be any files to unlock */
+ return -EINVAL;
/* sanity check */
if (size == 0)
@@ -240,6 +245,16 @@ static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
return nlmsvc_unlock_all_by_ip(sap);
}
+static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
+{
+ ssize_t ret;
+
+ mutex_lock(&nfsd_mutex);
+ ret = __write_unlock_ip(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return ret;
+}
+
/*
* write_unlock_fs - Release all locks on a local file system
*
@@ -254,11 +269,16 @@ static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
* returns one if one or more locks were not released
* On error: return code is negative errno value
*/
-static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
+static ssize_t __write_unlock_fs(struct file *file, char *buf, size_t size)
{
struct path path;
char *fo_path;
int error;
+ struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
+
+ if (!nn->nfsd_serv)
+ /* There cannot be any files to unlock */
+ return -EINVAL;
/* sanity check */
if (size == 0)
@@ -291,6 +311,16 @@ static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
return error;
}
+static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
+{
+ ssize_t ret;
+
+ mutex_lock(&nfsd_mutex);
+ ret = __write_unlock_fs(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return ret;
+}
+
/*
* write_filehandle - Get a variable-length NFS file handle by path
*
@@ -1082,10 +1112,14 @@ static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size)
case 'Y':
case 'y':
case '1':
- if (!nn->nfsd_serv)
+ mutex_lock(&nfsd_mutex);
+ if (!nn->nfsd_serv) {
+ mutex_unlock(&nfsd_mutex);
return -EBUSY;
+ }
trace_nfsd_end_grace(netns(file));
nfsd4_end_grace(nn);
+ mutex_unlock(&nfsd_mutex);
break;
default:
return -EINVAL;
--
2.49.0
