NFS: Add server and volume lists to /proc

Make two new proc files available:

	/proc/fs/nfsfs/servers
	/proc/fs/nfsfs/volumes

The first lists the servers with which we are currently dealing (struct
nfs_client), and the second lists the volumes we have on those servers (struct
nfs_server).

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 303 insertions, 0 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index dafba608c0a0..27f64781444a 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1148,3 +1148,287 @@ out_free_server:
         dprintk("<-- nfs_clone_server() = error %d\n", error);
         return ERR_PTR(error);
 }
+
+#ifdef CONFIG_PROC_FS
+static struct proc_dir_entry *proc_fs_nfs;
+
+static int nfs_server_list_open(struct inode *inode, struct file *file);
+static void *nfs_server_list_start(struct seq_file *p, loff_t *pos);
+static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos);
+static void nfs_server_list_stop(struct seq_file *p, void *v);
+static int nfs_server_list_show(struct seq_file *m, void *v);
+
+static struct seq_operations nfs_server_list_ops = {
+        .start  = nfs_server_list_start,
+        .next   = nfs_server_list_next,
+        .stop   = nfs_server_list_stop,
+        .show   = nfs_server_list_show,
+};
+
+static struct file_operations nfs_server_list_fops = {
+        .open           = nfs_server_list_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};
+
+static int nfs_volume_list_open(struct inode *inode, struct file *file);
+static void *nfs_volume_list_start(struct seq_file *p, loff_t *pos);
+static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos);
+static void nfs_volume_list_stop(struct seq_file *p, void *v);
+static int nfs_volume_list_show(struct seq_file *m, void *v);
+
+static struct seq_operations nfs_volume_list_ops = {
+        .start  = nfs_volume_list_start,
+        .next   = nfs_volume_list_next,
+        .stop   = nfs_volume_list_stop,
+        .show   = nfs_volume_list_show,
+};
+
+static struct file_operations nfs_volume_list_fops = {
+        .open           = nfs_volume_list_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};
+
+/*
+ * open "/proc/fs/nfsfs/servers" which provides a summary of servers with which
+ * we're dealing
+ */
+static int nfs_server_list_open(struct inode *inode, struct file *file)
+{
+        struct seq_file *m;
+        int ret;
+
+        ret = seq_open(file, &nfs_server_list_ops);
+        if (ret < 0)
+                return ret;
+
+        m = file->private_data;
+        m->private = PDE(inode)->data;
+
+        return 0;
+}
+
+/*
+ * set up the iterator to start reading from the server list and return the first item
+ */
+static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
+{
+        struct list_head *_p;
+        loff_t pos = *_pos;
+
+        /* lock the list against modification */
+        spin_lock(&nfs_client_lock);
+
+        /* allow for the header line */
+        if (!pos)
+                return SEQ_START_TOKEN;
+        pos--;
+
+        /* find the n'th element in the list */
+        list_for_each(_p, &nfs_client_list)
+                if (!pos--)
+                        break;
+
+        return _p != &nfs_client_list ? _p : NULL;
+}
+
+/*
+ * move to next server
+ */
+static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
+{
+        struct list_head *_p;
+
+        (*pos)++;
+
+        _p = v;
+        _p = (v == SEQ_START_TOKEN) ? nfs_client_list.next : _p->next;
+
+        return _p != &nfs_client_list ? _p : NULL;
+}
+
+/*
+ * clean up after reading from the transports list
+ */
+static void nfs_server_list_stop(struct seq_file *p, void *v)
+{
+        spin_unlock(&nfs_client_lock);
+}
+
+/*
+ * display a header line followed by a load of call lines
+ */
+static int nfs_server_list_show(struct seq_file *m, void *v)
+{
+        struct nfs_client *clp;
+
+        /* display header on line 1 */
+        if (v == SEQ_START_TOKEN) {
+                seq_puts(m, "NV SERVER   PORT USE HOSTNAME\n");
+                return 0;
+        }
+
+        /* display one transport per line on subsequent lines */
+        clp = list_entry(v, struct nfs_client, cl_share_link);
+
+        seq_printf(m, "v%d %02x%02x%02x%02x %4hx %3d %s\n",
+                   clp->cl_nfsversion,
+                   NIPQUAD(clp->cl_addr.sin_addr),
+                   ntohs(clp->cl_addr.sin_port),
+                   atomic_read(&clp->cl_count),
+                   clp->cl_hostname);
+
+        return 0;
+}
+
+/*
+ * open "/proc/fs/nfsfs/volumes" which provides a summary of extant volumes
+ */
+static int nfs_volume_list_open(struct inode *inode, struct file *file)
+{
+        struct seq_file *m;
+        int ret;
+
+        ret = seq_open(file, &nfs_volume_list_ops);
+        if (ret < 0)
+                return ret;
+
+        m = file->private_data;
+        m->private = PDE(inode)->data;
+
+        return 0;
+}
+
+/*
+ * set up the iterator to start reading from the volume list and return the first item
+ */
+static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
+{
+        struct list_head *_p;
+        loff_t pos = *_pos;
+
+        /* lock the list against modification */
+        spin_lock(&nfs_client_lock);
+
+        /* allow for the header line */
+        if (!pos)
+                return SEQ_START_TOKEN;
+        pos--;
+
+        /* find the n'th element in the list */
+        list_for_each(_p, &nfs_volume_list)
+                if (!pos--)
+                        break;
+
+        return _p != &nfs_volume_list ? _p : NULL;
+}
+
+/*
+ * move to next volume
+ */
+static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
+{
+        struct list_head *_p;
+
+        (*pos)++;
+
+        _p = v;
+        _p = (v == SEQ_START_TOKEN) ? nfs_volume_list.next : _p->next;
+
+        return _p != &nfs_volume_list ? _p : NULL;
+}
+
+/*
+ * clean up after reading from the transports list
+ */
+static void nfs_volume_list_stop(struct seq_file *p, void *v)
+{
+        spin_unlock(&nfs_client_lock);
+}
+
+/*
+ * display a header line followed by a load of call lines
+ */
+static int nfs_volume_list_show(struct seq_file *m, void *v)
+{
+        struct nfs_server *server;
+        struct nfs_client *clp;
+        char dev[8], fsid[17];
+
+        /* display header on line 1 */
+        if (v == SEQ_START_TOKEN) {
+                seq_puts(m, "NV SERVER   PORT DEV     FSID\n");
+                return 0;
+        }
+        /* display one transport per line on subsequent lines */
+        server = list_entry(v, struct nfs_server, master_link);
+        clp = server->nfs_client;
+
+        snprintf(dev, 8, "%u:%u",
+                 MAJOR(server->s_dev), MINOR(server->s_dev));
+
+        snprintf(fsid, 17, "%llx:%llx",
+                 server->fsid.major, server->fsid.minor);
+
+        seq_printf(m, "v%d %02x%02x%02x%02x %4hx %-7s %-17s\n",
+                   clp->cl_nfsversion,
+                   NIPQUAD(clp->cl_addr.sin_addr),
+                   ntohs(clp->cl_addr.sin_port),
+                   dev,
+                   fsid);
+
+        return 0;
+}
+
+/*
+ * initialise the /proc/fs/nfsfs/ directory
+ */
+int __init nfs_fs_proc_init(void)
+{
+        struct proc_dir_entry *p;
+
+        proc_fs_nfs = proc_mkdir("nfsfs", proc_root_fs);
+        if (!proc_fs_nfs)
+                goto error_0;
+
+        proc_fs_nfs->owner = THIS_MODULE;
+
+        /* a file of servers with which we're dealing */
+        p = create_proc_entry("servers", S_IFREG|S_IRUGO, proc_fs_nfs);
+        if (!p)
+                goto error_1;
+
+        p->proc_fops = &nfs_server_list_fops;
+        p->owner = THIS_MODULE;
+
+        /* a file of volumes that we have mounted */
+        p = create_proc_entry("volumes", S_IFREG|S_IRUGO, proc_fs_nfs);
+        if (!p)
+                goto error_2;
+
+        p->proc_fops = &nfs_volume_list_fops;
+        p->owner = THIS_MODULE;
+        return 0;
+
+error_2:
+        remove_proc_entry("servers", proc_fs_nfs);
+error_1:
+        remove_proc_entry("nfsfs", proc_root_fs);
+error_0:
+        return -ENOMEM;
+}
+
+/*
+ * clean up the /proc/fs/nfsfs/ directory
+ */
+void nfs_fs_proc_exit(void)
+{
+        remove_proc_entry("volumes", proc_fs_nfs);
+        remove_proc_entry("servers", proc_fs_nfs);
+        remove_proc_entry("nfsfs", proc_root_fs);
+}
+
+#endif /* CONFIG_PROC_FS */
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index a547c58a83e6..cb5c65f0bc12 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1141,6 +1141,10 @@ static int __init init_nfs_fs(void)
 {
         int err;
 
+        err = nfs_fs_proc_init();
+        if (err)
+                goto out5;
+
         err = nfs_init_nfspagecache();
         if (err)
                 goto out4;
@@ -1181,6 +1185,8 @@ out2:
 out3:
         nfs_destroy_nfspagecache();
 out4:
+        nfs_fs_proc_exit();
+out5:
         return err;
 }
 
@@ -1195,6 +1201,7 @@ static void __exit exit_nfs_fs(void)
         rpc_proc_unregister("nfs");
 #endif
         unregister_nfs_fs();
+        nfs_fs_proc_exit();
 }
 
 /* Not quite true; I just maintain it */
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index e73ba4f1052a..bea0b016bd70 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -47,6 +47,18 @@ extern void nfs_free_server(struct nfs_server *server);
 extern struct nfs_server *nfs_clone_server(struct nfs_server *,
                                            struct nfs_fh *,
                                            struct nfs_fattr *);
+#ifdef CONFIG_PROC_FS
+extern int __init nfs_fs_proc_init(void);
+extern void nfs_fs_proc_exit(void);
+#else
+static inline int nfs_fs_proc_init(void)
+{
+        return 0;
+}
+static inline void nfs_fs_proc_exit(void)
+{
+}
+#endif
 
 /* nfs4namespace.c */
 #ifdef CONFIG_NFS_V4