write_foo functions are called to handle IO to files in /proc/fs/nfsd/.
The 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-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
fs/nfsd/nfsctl.c | 115 +++++++++++++++++++++++++++++++----------------
1 file changed, 77 insertions(+), 38 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 3f3e9f6c4250..3710a1992d17 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -200,27 +200,18 @@ static inline struct net *netns(struct file *file)
return file_inode(file)->i_sb->s_fs_info;
}
-/*
- * write_unlock_ip - Release all locks used by a client
- *
- * Experimental.
- *
- * Input:
- * buf: '\n'-terminated C string containing a
- * presentation format IP address
- * size: length of C string in @buf
- * Output:
- * On success: returns zero if all specified locks were released;
- * 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)
@@ -241,24 +232,39 @@ static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
}
/*
- * write_unlock_fs - Release all locks on a local file system
+ * write_unlock_ip - Release all locks used by a client
*
* Experimental.
*
* Input:
- * buf: '\n'-terminated C string containing the
- * absolute pathname of a local file system
+ * buf: '\n'-terminated C string containing a
+ * presentation format IP address
* size: length of C string in @buf
* Output:
* On success: returns zero if all specified locks were released;
* 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_ip(struct file *file, char *buf, size_t size)
+{
+ ssize_t rv;
+
+ mutex_lock(&nfsd_mutex);
+ rv = __write_unlock_ip(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return rv;
+}
+
+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 +297,30 @@ static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
return error;
}
+/*
+ * write_unlock_fs - Release all locks on a local file system
+ *
+ * Experimental.
+ *
+ * Input:
+ * buf: '\n'-terminated C string containing the
+ * absolute pathname of a local file system
+ * size: length of C string in @buf
+ * Output:
+ * On success: returns zero if all specified locks were released;
+ * 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)
+{
+ ssize_t rv;
+
+ mutex_lock(&nfsd_mutex);
+ rv = __write_unlock_fs(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return rv;
+}
+
/*
* write_filehandle - Get a variable-length NFS file handle by path
*
@@ -1053,6 +1083,29 @@ static ssize_t write_recoverydir(struct file *file, char *buf, size_t size)
}
#endif
+static ssize_t __write_v4_end_grace(struct file *file, char *buf, size_t size)
+{
+ struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
+
+ if (size > 0) {
+ switch(buf[0]) {
+ case 'Y':
+ case 'y':
+ case '1':
+ if (!nn->nfsd_serv)
+ return -EBUSY;
+ trace_nfsd_end_grace(netns(file));
+ nfsd4_end_grace(nn);
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%c\n",
+ nn->grace_ended ? 'Y' : 'N');
+}
+
/*
* write_v4_end_grace - release grace period for nfsd's v4.x lock manager
*
@@ -1075,27 +1128,13 @@ static ssize_t write_recoverydir(struct file *file, char *buf, size_t size)
*/
static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size)
{
- struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
-
- if (size > 0) {
- switch(buf[0]) {
- case 'Y':
- case 'y':
- case '1':
- if (!nn->nfsd_serv)
- return -EBUSY;
- trace_nfsd_end_grace(netns(file));
- nfsd4_end_grace(nn);
- break;
- default:
- return -EINVAL;
- }
- }
+ ssize_t rv;
- return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%c\n",
- nn->grace_ended ? 'Y' : 'N');
+ mutex_lock(&nfsd_mutex);
+ rv = __write_v4_end_grace(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return rv;
}
-
#endif
/*----------------------------------------------------------------------------*/
--
2.49.0
