NFSD: Add documenting comments for nfsctl interface

Document the NFSD sysctl interface laid out in fs/nfsd/nfsctl.c.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 437 insertions, 16 deletions

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 856b8646a480..3d93b2064ce5 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -175,10 +175,24 @@ static const struct file_operations exports_operations = {
 /*----------------------------------------------------------------------------*/
 /*
  * payload - write methods
- * If the method has a response, the response should be put in buf,
- * and the length returned.  Otherwise return 0 or and -error.
  */
 
+/**
+ * write_svc - Start kernel's NFSD server
+ *
+ * Deprecated.  /proc/fs/nfsd/threads is preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_svc
+ *                              svc_port:       port number of this
+ *                                              server's listener
+ *                              svc_nthreads:   number of threads to start
+ *                      size:   size in bytes of passed in nfsctl_svc
+ * Output:
+ *      On success:     returns zero
+ *      On error:       return code is negative errno value
+ */
 static ssize_t write_svc(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_svc *data;
@@ -188,6 +202,30 @@ static ssize_t write_svc(struct file *file, char *buf, size_t size)
         return nfsd_svc(data->svc_port, data->svc_nthreads);
 }
 
+/**
+ * write_add - Add or modify client entry in auth unix cache
+ *
+ * Deprecated.  /proc/net/rpc/auth.unix.ip is preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_client
+ *                              cl_ident:       '\0'-terminated C string
+ *                                              containing domain name
+ *                                              of client
+ *                              cl_naddr:       no. of items in cl_addrlist
+ *                              cl_addrlist:    array of client addresses
+ *                              cl_fhkeytype:   ignored
+ *                              cl_fhkeylen:    ignored
+ *                              cl_fhkey:       ignored
+ *                      size:   size in bytes of passed in nfsctl_client
+ * Output:
+ *      On success:     returns zero
+ *      On error:       return code is negative errno value
+ *
+ * Note: Only AF_INET client addresses are passed in, since
+ * nfsctl_client.cl_addrlist contains only in_addr fields for addresses.
+ */
 static ssize_t write_add(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_client *data;
@@ -197,6 +235,30 @@ static ssize_t write_add(struct file *file, char *buf, size_t size)
         return exp_addclient(data);
 }
 
+/**
+ * write_del - Remove client from auth unix cache
+ *
+ * Deprecated.  /proc/net/rpc/auth.unix.ip is preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_client
+ *                              cl_ident:       '\0'-terminated C string
+ *                                              containing domain name
+ *                                              of client
+ *                              cl_naddr:       ignored
+ *                              cl_addrlist:    ignored
+ *                              cl_fhkeytype:   ignored
+ *                              cl_fhkeylen:    ignored
+ *                              cl_fhkey:       ignored
+ *                      size:   size in bytes of passed in nfsctl_client
+ * Output:
+ *      On success:     returns zero
+ *      On error:       return code is negative errno value
+ *
+ * Note: Only AF_INET client addresses are passed in, since
+ * nfsctl_client.cl_addrlist contains only in_addr fields for addresses.
+ */
 static ssize_t write_del(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_client *data;
@@ -206,6 +268,33 @@ static ssize_t write_del(struct file *file, char *buf, size_t size)
         return exp_delclient(data);
 }
 
+/**
+ * write_export - Export part or all of a local file system
+ *
+ * Deprecated.  /proc/net/rpc/{nfsd.export,nfsd.fh} are preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_export
+ *                              ex_client:      '\0'-terminated C string
+ *                                              containing domain name
+ *                                              of client allowed to access
+ *                                              this export
+ *                              ex_path:        '\0'-terminated C string
+ *                                              containing pathname of
+ *                                              directory in local file system
+ *                              ex_dev:         fsid to use for this export
+ *                              ex_ino:         ignored
+ *                              ex_flags:       export flags for this export
+ *                              ex_anon_uid:    UID to use for anonymous
+ *                                              requests
+ *                              ex_anon_gid:    GID to use for anonymous
+ *                                              requests
+ *                      size:   size in bytes of passed in nfsctl_export
+ * Output:
+ *      On success:     returns zero
+ *      On error:       return code is negative errno value
+ */
 static ssize_t write_export(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_export *data;
@@ -215,6 +304,31 @@ static ssize_t write_export(struct file *file, char *buf, size_t size)
         return exp_export(data);
 }
 
+/**
+ * write_unexport - Unexport a previously exported file system
+ *
+ * Deprecated.  /proc/net/rpc/{nfsd.export,nfsd.fh} are preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_export
+ *                              ex_client:      '\0'-terminated C string
+ *                                              containing domain name
+ *                                              of client no longer allowed
+ *                                              to access this export
+ *                              ex_path:        '\0'-terminated C string
+ *                                              containing pathname of
+ *                                              directory in local file system
+ *                              ex_dev:         ignored
+ *                              ex_ino:         ignored
+ *                              ex_flags:       ignored
+ *                              ex_anon_uid:    ignored
+ *                              ex_anon_gid:    ignored
+ *                      size:   size in bytes of passed in nfsctl_export
+ * Output:
+ *      On success:     returns zero
+ *      On error:       return code is negative errno value
+ */
 static ssize_t write_unexport(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_export *data;
@@ -225,6 +339,30 @@ static ssize_t write_unexport(struct file *file, char *buf, size_t size)
         return exp_unexport(data);
 }
 
+/**
+ * write_getfs - Get a variable-length NFS file handle by path
+ *
+ * Deprecated.  /proc/fs/nfsd/filehandle is preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_fsparm
+ *                              gd_addr:        socket address of client
+ *                              gd_path:        '\0'-terminated C string
+ *                                              containing pathname of
+ *                                              directory in local file system
+ *                              gd_maxlen:      maximum size of returned file
+ *                                              handle
+ *                      size:   size in bytes of passed in nfsctl_fsparm
+ * Output:
+ *      On success:     passed-in buffer filled with a knfsd_fh structure
+ *                      (a variable-length raw NFS file handle);
+ *                      return code is the size in bytes of the file handle
+ *      On error:       return code is negative errno value
+ *
+ * Note: Only AF_INET client addresses are passed in, since gd_addr
+ * is the same size as a struct sockaddr_in.
+ */
 static ssize_t write_getfs(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_fsparm *data;
@@ -264,6 +402,29 @@ static ssize_t write_getfs(struct file *file, char *buf, size_t size)
         return err;
 }
 
+/**
+ * write_getfd - Get a fixed-length NFS file handle by path (used by mountd)
+ *
+ * Deprecated.  /proc/fs/nfsd/filehandle is preferred.
+ * Function remains to support old versions of nfs-utils.
+ *
+ * Input:
+ *                      buf:    struct nfsctl_fdparm
+ *                              gd_addr:        socket address of client
+ *                              gd_path:        '\0'-terminated C string
+ *                                              containing pathname of
+ *                                              directory in local file system
+ *                              gd_version:     fdparm structure version
+ *                      size:   size in bytes of passed in nfsctl_fdparm
+ * Output:
+ *      On success:     passed-in buffer filled with nfsctl_res
+ *                      (a fixed-length raw NFS file handle);
+ *                      return code is the size in bytes of the file handle
+ *      On error:       return code is negative errno value
+ *
+ * Note: Only AF_INET client addresses are passed in, since gd_addr
+ * is the same size as a struct sockaddr_in.
+ */
 static ssize_t write_getfd(struct file *file, char *buf, size_t size)
 {
         struct nfsctl_fdparm *data;
@@ -308,6 +469,22 @@ static ssize_t write_getfd(struct file *file, char *buf, size_t size)
         return err;
 }
 
+/**
+ * write_unlock_ip - Release all locks used by a client
+ *
+ * Experimental.
+ *
+ * Input:
+ *                      buf:    '\n'-terminated C string containing a
+ *                              presentation format IPv4 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
+ *
+ * Note: Only AF_INET client addresses are passed in
+ */
 static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
 {
         struct sockaddr_in sin = {
@@ -338,6 +515,20 @@ static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
         return nlmsvc_unlock_all_by_ip((struct sockaddr *)&sin);
 }
 
+/**
+ * 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)
 {
         struct path path;
@@ -359,21 +550,44 @@ static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
         if (error)
                 return error;
 
+        /*
+         * XXX: Needs better sanity checking.  Otherwise we could end up
+         * releasing locks on the wrong file system.
+         *
+         * For example:
+         * 1.  Does the path refer to a directory?
+         * 2.  Is that directory a mount point, or
+         * 3.  Is that directory the root of an exported file system?
+         */
         error = nlmsvc_unlock_all_by_sb(path.mnt->mnt_sb);
 
         path_put(&path);
         return error;
 }
 
+/**
+ * write_filehandle - Get a variable-length NFS file handle by path
+ *
+ * On input, the buffer contains a '\n'-terminated C string comprised of
+ * three alphanumeric words separated by whitespace.  The string may
+ * contain escape sequences.
+ *
+ * Input:
+ *                      buf:
+ *                              domain:         client domain name
+ *                              path:           export pathname
+ *                              maxsize:        numeric maximum size of
+ *                                              @buf
+ *                      size:   length of C string in @buf
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C
+ *                      string containing a ASCII hex text version
+ *                      of the NFS file handle;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is negative errno value
+ */
 static ssize_t write_filehandle(struct file *file, char *buf, size_t size)
 {
-        /* request is:
-         *   domain path maxsize
-         * response is
-         *   filehandle
-         *
-         * qword quoting is used, so filehandle will be \x....
-         */
         char *dname, *path;
         int uninitialized_var(maxsize);
         char *mesg = buf;
@@ -427,11 +641,36 @@ static ssize_t write_filehandle(struct file *file, char *buf, size_t size)
         return mesg - buf;      
 }
 
+/**
+ * write_threads - Start NFSD, or report the current number of running threads
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C
+ *                      string numeric value representing the number of
+ *                      running NFSD threads;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing an unsigned
+ *                                      integer value representing the
+ *                                      number of NFSD threads to start
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     NFS service is started;
+ *                      passed-in buffer filled with '\n'-terminated C
+ *                      string numeric value representing the number of
+ *                      running NFSD threads;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_threads(struct file *file, char *buf, size_t size)
 {
-        /* if size > 0, look for a number of threads and call nfsd_svc
-         * then write out number of threads as reply
-         */
         char *mesg = buf;
         int rv;
         if (size > 0) {
@@ -449,6 +688,28 @@ static ssize_t write_threads(struct file *file, char *buf, size_t size)
         return strlen(buf);
 }
 
+/**
+ * write_pool_threads - Set or report the current number of threads per pool
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing whitespace-
+ *                                      separated unsigned integer values
+ *                                      representing the number of NFSD
+ *                                      threads to start in each pool
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C
+ *                      string containing integer values representing the
+ *                      number of NFSD threads in each pool;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_pool_threads(struct file *file, char *buf, size_t size)
 {
         /* if size > 0, look for an array of number of threads per node
@@ -519,10 +780,6 @@ out_free:
 
 static ssize_t __write_versions(struct file *file, char *buf, size_t size)
 {
-        /*
-         * Format:
-         *   [-/+]vers [-/+]vers ...
-         */
         char *mesg = buf;
         char *vers, sign;
         int len, num;
@@ -580,6 +837,38 @@ static ssize_t __write_versions(struct file *file, char *buf, size_t size)
         return len;
 }
 
+/**
+ * write_versions - Set or report the available NFS protocol versions
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C
+ *                      string containing positive or negative integer
+ *                      values representing the current status of each
+ *                      protocol version;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing whitespace-
+ *                                      separated positive or negative
+ *                                      integer values representing NFS
+ *                                      protocol versions to enable ("+n")
+ *                                      or disable ("-n")
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     status of zero or more protocol versions has
+ *                      been updated; passed-in buffer filled with
+ *                      '\n'-terminated C string containing positive
+ *                      or negative integer values representing the
+ *                      current status of each protocol version;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_versions(struct file *file, char *buf, size_t size)
 {
         ssize_t rv;
@@ -689,6 +978,75 @@ static ssize_t __write_ports(struct file *file, char *buf, size_t size)
         return -EINVAL;
 }
 
+/**
+ * write_ports - Pass a socket file descriptor or transport name to listen on
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ * Output:
+ *      On success:     passed-in buffer filled with a '\n'-terminated C
+ *                      string containing a whitespace-separated list of
+ *                      named NFSD listeners;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing an unsigned
+ *                                      integer value representing a bound
+ *                                      but unconnected socket that is to be
+ *                                      used as an NFSD listener
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     NFS service is started;
+ *                      passed-in buffer filled with a '\n'-terminated C
+ *                      string containing a unique alphanumeric name of
+ *                      the listener;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing a "-" followed
+ *                                      by an integer value representing a
+ *                                      previously passed in socket file
+ *                                      descriptor
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     NFS service no longer listens on that socket;
+ *                      passed-in buffer filled with a '\n'-terminated C
+ *                      string containing a unique name of the listener;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing a transport
+ *                                      name and an unsigned integer value
+ *                                      representing the port to listen on,
+ *                                      separated by whitespace
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     returns zero; NFS service is started
+ *      On error:       return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing a "-" followed
+ *                                      by a transport name and an unsigned
+ *                                      integer value representing the port
+ *                                      to listen on, separated by whitespace
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     returns zero; NFS service no longer listens
+ *                      on that transport
+ *      On error:       return code is a negative errno value
+ */
 static ssize_t write_ports(struct file *file, char *buf, size_t size)
 {
         ssize_t rv;
@@ -702,6 +1060,27 @@ static ssize_t write_ports(struct file *file, char *buf, size_t size)
 
 int nfsd_max_blksize;
 
+/**
+ * write_maxblksize - Set or report the current NFS blksize
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing an unsigned
+ *                                      integer value representing the new
+ *                                      NFS blksize
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C string
+ *                      containing numeric value of the current NFS blksize
+ *                      setting;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_maxblksize(struct file *file, char *buf, size_t size)
 {
         char *mesg = buf;
@@ -754,6 +1133,27 @@ static ssize_t __write_leasetime(struct file *file, char *buf, size_t size)
         return strlen(buf);
 }
 
+/**
+ * write_leasetime - Set or report the current NFSv4 lease time
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing an unsigned
+ *                                      integer value representing the new
+ *                                      NFSv4 lease expiry time
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C
+ *                      string containing unsigned integer value of the
+ *                      current lease expiry time;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_leasetime(struct file *file, char *buf, size_t size)
 {
         ssize_t rv;
@@ -790,6 +1190,27 @@ static ssize_t __write_recoverydir(struct file *file, char *buf, size_t size)
         return strlen(buf);
 }
 
+/**
+ * write_recoverydir - Set or report the pathname of the recovery directory
+ *
+ * Input:
+ *                      buf:            ignored
+ *                      size:           zero
+ *
+ * OR
+ *
+ * Input:
+ *                      buf:            C string containing the pathname
+ *                                      of the directory on a local file
+ *                                      system containing permanent NFSv4
+ *                                      recovery data
+ *                      size:           non-zero length of C string in @buf
+ * Output:
+ *      On success:     passed-in buffer filled with '\n'-terminated C string
+ *                      containing the current recovery pathname setting;
+ *                      return code is the size in bytes of the string
+ *      On error:       return code is zero or a negative errno value
+ */
 static ssize_t write_recoverydir(struct file *file, char *buf, size_t size)
 {
         ssize_t rv;