9p: Implement show_options

Implement the show_options superblock op for 9p as part of a bid to get
rid of s_options and generic_show_options() to make it easier to implement
a context-based mount where the mount options can be passed individually
over a file descriptor.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Ron Minnich <rminnich@sandia.gov>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: v9fs-developer@lists.sourceforge.net
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 61 insertions, 0 deletions

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index c202930086ed..8fb89ddc6cc7 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -33,6 +33,7 @@
 #include <linux/parser.h>
 #include <linux/idr.h>
 #include <linux/slab.h>
+#include <linux/seq_file.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 #include <net/9p/transport.h>
@@ -82,6 +83,13 @@ static const match_table_t tokens = {
         {Opt_err, NULL}
 };
 
+static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
+        [CACHE_NONE]    = "none",
+        [CACHE_MMAP]    = "mmap",
+        [CACHE_LOOSE]   = "loose",
+        [CACHE_FSCACHE] = "fscache",
+};
+
 /* Interpret mount options for cache mode */
 static int get_cache_mode(char *s)
 {
@@ -104,6 +112,58 @@ static int get_cache_mode(char *s)
         return version;
 }
 
+/*
+ * Display the mount options in /proc/mounts.
+ */
+int v9fs_show_options(struct seq_file *m, struct dentry *root)
+{
+        struct v9fs_session_info *v9ses = root->d_sb->s_fs_info;
+
+        if (v9ses->debug)
+                seq_printf(m, ",debug=%x", v9ses->debug);
+        if (!uid_eq(v9ses->dfltuid, V9FS_DEFUID))
+                seq_printf(m, ",dfltuid=%u",
+                           from_kuid_munged(&init_user_ns, v9ses->dfltuid));
+        if (!gid_eq(v9ses->dfltgid, V9FS_DEFGID))
+                seq_printf(m, ",dfltgid=%u",
+                           from_kgid_munged(&init_user_ns, v9ses->dfltgid));
+        if (v9ses->afid != ~0)
+                seq_printf(m, ",afid=%u", v9ses->afid);
+        if (strcmp(v9ses->uname, V9FS_DEFUSER) != 0)
+                seq_printf(m, ",uname=%s", v9ses->uname);
+        if (strcmp(v9ses->aname, V9FS_DEFANAME) != 0)
+                seq_printf(m, ",aname=%s", v9ses->aname);
+        if (v9ses->nodev)
+                seq_puts(m, ",nodevmap");
+        if (v9ses->cache)
+                seq_printf(m, ",%s", v9fs_cache_modes[v9ses->cache]);
+#ifdef CONFIG_9P_FSCACHE
+        if (v9ses->cachetag && v9ses->cache == CACHE_FSCACHE)
+                seq_printf(m, ",cachetag=%s", v9ses->cachetag);
+#endif
+
+        switch (v9ses->flags & V9FS_ACCESS_MASK) {
+        case V9FS_ACCESS_USER:
+                seq_puts(m, ",access=user");
+                break;
+        case V9FS_ACCESS_ANY:
+                seq_puts(m, ",access=any");
+                break;
+        case V9FS_ACCESS_CLIENT:
+                seq_puts(m, ",access=client");
+                break;
+        case V9FS_ACCESS_SINGLE:
+                seq_printf(m, ",access=%u",
+                           from_kuid_munged(&init_user_ns, v9ses->uid));
+                break;
+        }
+
+        if (v9ses->flags & V9FS_POSIX_ACL)
+                seq_puts(m, ",posixacl");
+
+        return p9_show_client_options(m, v9ses->clnt);
+}
+
 /**
  * v9fs_parse_options - parse mount options into session structure
  * @v9ses: existing v9fs session information
@@ -230,6 +290,7 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
                         break;
                 case Opt_cachetag:
 #ifdef CONFIG_9P_FSCACHE
+                        kfree(v9ses->cachetag);
                         v9ses->cachetag = match_strdup(&args[0]);
 #endif
                         break;