nfs: Show original device name verbatim in /proc/*/mount{s,info}

commit 97a54868262da1629a3e65121e65b8e8c4419d9f upstream.

Since commit c7f404b ('vfs: new superblock methods to override
/proc/*/mount{s,info}'), nfs_path() is used to generate the mounted
device name reported back to userland.

nfs_path() always generates a trailing slash when the given dentry is
the root of an NFS mount, but userland may expect the original device
name to be returned verbatim (as it used to be).  Make this
canonicalisation optional and change the callers accordingly.

[jrnieder@gmail.com: use flag instead of bool argument]
Reported-and-tested-by: Chris Hiestand <chiestand@salk.edu>
Reference: http://bugs.debian.org/669314
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 31fdb03225cd0ed989424dddf361698394aa1241..e794deeada24ddf7c86a592b0c20cd5425d4fbb5 100644 (file)
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -353,8 +353,9 @@ extern void nfs_sb_active(struct super_block *sb);
 extern void nfs_sb_deactive(struct super_block *sb);
 
 /* namespace.c */
+#define NFS_PATH_CANONICAL 1
 extern char *nfs_path(char **p, struct dentry *dentry,
-                     char *buffer, ssize_t buflen);
+                     char *buffer, ssize_t buflen, unsigned flags);
 extern struct vfsmount *nfs_d_automount(struct path *path);
 struct vfsmount *nfs_submount(struct nfs_server *, struct dentry *,
                              struct nfs_fh *, struct nfs_fattr *);
@@ -491,7 +492,7 @@ static inline char *nfs_devname(struct dentry *dentry,
                                char *buffer, ssize_t buflen)
 {
        char *dummy;
-       return nfs_path(&dummy, dentry, buffer, buflen);
+       return nfs_path(&dummy, dentry, buffer, buflen, NFS_PATH_CANONICAL);
 }
 
 /*

diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 655925373b9161c6a6c64ad157002d10cf8064e2..dd057bc6b65b28d3822229e0c0d5d0777b7955b9 100644 (file)
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -33,6 +33,7 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
+ * @flags - options (see below)
  *
  * Helper function for constructing the server pathname
  * by arbitrary hashed dentry.
@@ -40,8 +41,14 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * This is mainly for use in figuring out the path on the
  * server side when automounting on top of an existing partition
  * and in generating /proc/mounts and friends.
+ *
+ * Supported flags:
+ * NFS_PATH_CANONICAL: ensure there is exactly one slash after
+ *                    the original device (export) name
+ *                    (if unset, the original name is returned verbatim)
  */
-char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
+              unsigned flags)
 {
        char *end;
        int namelen;
@@ -74,7 +81,7 @@ rename_retry:
                rcu_read_unlock();
                goto rename_retry;
        }
-       if (*end != '/') {
+       if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
                if (--buflen < 0) {
                        spin_unlock(&dentry->d_lock);
                        rcu_read_unlock();
@@ -91,9 +98,11 @@ rename_retry:
                return end;
        }
        namelen = strlen(base);
-       /* Strip off excess slashes in base string */
-       while (namelen > 0 && base[namelen - 1] == '/')
-               namelen--;
+       if (flags & NFS_PATH_CANONICAL) {
+               /* Strip off excess slashes in base string */
+               while (namelen > 0 && base[namelen - 1] == '/')
+                       namelen--;
+       }
        buflen -= namelen;
        if (buflen < 0) {
                spin_unlock(&dentry->d_lock);

diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index 017b4b01a69c7a747b4afab8c7591b5f2ac59a20..c077b254ec9cb239a348303d63a2b2f67b10ade0 100644 (file)
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -81,7 +81,8 @@ static char *nfs_path_component(const char *nfspath, const char *end)
 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
 {
        char *limit;
-       char *path = nfs_path(&limit, dentry, buffer, buflen);
+       char *path = nfs_path(&limit, dentry, buffer, buflen,
+                             NFS_PATH_CANONICAL);
        if (!IS_ERR(path)) {
                char *path_component = nfs_path_component(path, limit);
                if (path_component)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index b8eda700584bfbd25086d898a21b3fd03959030d..d8d73969c07b1d361e713996ae5f247a4e2abefc 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -765,7 +765,7 @@ int nfs_show_devname(struct seq_file *m, struct dentry *root)
        int err = 0;
        if (!page)
                return -ENOMEM;
-       devname = nfs_path(&dummy, root, page, PAGE_SIZE);
+       devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
        if (IS_ERR(devname))
                err = PTR_ERR(devname);
        else