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 4f10d8188ab6e49168568a658b699d67c5935004..399a505e024e860f166dedc95f0c81bededf44a5 100644 (file)
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -274,8 +274,9 @@ 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);
 
 /* getroot.c */
@@ -349,7 +350,7 @@ 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 1f063bacd2857caa119f4dce1bf429402b0be909..d6122ef16f4174e2b0064f170c9f0f04d883e75b 100644 (file)
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -37,6 +37,7 @@ static struct vfsmount *nfs_do_submount(struct dentry *dentry,
  * @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.
@@ -44,8 +45,14 @@ static struct vfsmount *nfs_do_submount(struct dentry *dentry,
  * 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;
@@ -78,7 +85,7 @@ 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();
@@ -95,9 +102,11 @@ 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 bb80c49b6533b44aab58171dcd69397ff02f39a2..96f2b67aac30a8059a90afaaeb9280562750ba70 100644 (file)
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -57,7 +57,8 @@ Elong:
 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 *colon = strchr(path, ':');
                if (colon && colon < limit)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index a1f3d6e57f082e246e7fec2b8e65a8e6fd6ddf14..23f02232a51def8b9c70f3c943af9e5a20bae6ba 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -763,7 +763,7 @@ static int nfs_show_devname(struct seq_file *m, struct vfsmount *mnt)
        int err = 0;
        if (!page)
                return -ENOMEM;
-       devname = nfs_path(&dummy, mnt->mnt_root, page, PAGE_SIZE);
+       devname = nfs_path(&dummy, mnt->mnt_root, page, PAGE_SIZE, 0);
        if (IS_ERR(devname))
                err = PTR_ERR(devname);
        else