1 files changed, 45 insertions, 24 deletions

diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index f32b8603dca8..859cdaba4c1c 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -25,33 +25,31 @@ static LIST_HEAD(nfs_automount_list);
 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
 int nfs_mountpoint_expiry_timeout = 500 * HZ;
 
-static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
-                                        const struct dentry *dentry,
+static struct vfsmount *nfs_do_submount(struct super_block *sb,
+                                        struct dentry *dentry,
                                         struct nfs_fh *fh,
                                         struct nfs_fattr *fattr);
 
 /*
  * nfs_path - reconstruct the path given an arbitrary dentry
- * @base - arbitrary string to prepend to the path
- * @droot - pointer to root dentry for mountpoint
+ * @base - used to return pointer to the end of devname part of path
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
  *
- * Helper function for constructing the path from the
- * root dentry to an arbitrary hashed dentry.
+ * Helper function for constructing the server pathname
+ * by arbitrary hashed dentry.
  *
  * This is mainly for use in figuring out the path on the
- * server side when automounting on top of an existing partition.
+ * server side when automounting on top of an existing partition
+ * and in generating /proc/mounts and friends.
  */
-char *nfs_path(const char *base,
-               const struct dentry *droot,
-               const struct dentry *dentry,
-               char *buffer, ssize_t buflen)
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
 {
         char *end;
         int namelen;
         unsigned seq;
+        const char *base;
 
 rename_retry:
         end = buffer+buflen;
@@ -60,7 +58,10 @@ rename_retry:
 
         seq = read_seqbegin(&rename_lock);
         rcu_read_lock();
-        while (!IS_ROOT(dentry) && dentry != droot) {
+        while (1) {
+                spin_lock(&dentry->d_lock);
+                if (IS_ROOT(dentry))
+                        break;
                 namelen = dentry->d_name.len;
                 buflen -= namelen + 1;
                 if (buflen < 0)
@@ -68,27 +69,47 @@ rename_retry:
                 end -= namelen;
                 memcpy(end, dentry->d_name.name, namelen);
                 *--end = '/';
+                spin_unlock(&dentry->d_lock);
                 dentry = dentry->d_parent;
         }
-        rcu_read_unlock();
-        if (read_seqretry(&rename_lock, seq))
+        if (read_seqretry(&rename_lock, seq)) {
+                spin_unlock(&dentry->d_lock);
+                rcu_read_unlock();
                 goto rename_retry;
+        }
         if (*end != '/') {
-                if (--buflen < 0)
+                if (--buflen < 0) {
+                        spin_unlock(&dentry->d_lock);
+                        rcu_read_unlock();
                         goto Elong;
+                }
                 *--end = '/';
         }
+        *p = end;
+        base = dentry->d_fsdata;
+        if (!base) {
+                spin_unlock(&dentry->d_lock);
+                rcu_read_unlock();
+                WARN_ON(1);
+                return end;
+        }
         namelen = strlen(base);
         /* Strip off excess slashes in base string */
         while (namelen > 0 && base[namelen - 1] == '/')
                 namelen--;
         buflen -= namelen;
-        if (buflen < 0)
+        if (buflen < 0) {
+                spin_lock(&dentry->d_lock);
+                rcu_read_unlock();
                 goto Elong;
+        }
         end -= namelen;
         memcpy(end, base, namelen);
+        spin_unlock(&dentry->d_lock);
+        rcu_read_unlock();
         return end;
 Elong_unlock:
+        spin_lock(&dentry->d_lock);
         rcu_read_unlock();
         if (read_seqretry(&rename_lock, seq))
                 goto rename_retry;
@@ -143,9 +164,9 @@ struct vfsmount *nfs_d_automount(struct path *path)
         }
 
         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
-                mnt = nfs_do_refmount(path->mnt, path->dentry);
+                mnt = nfs_do_refmount(path->mnt->mnt_sb, path->dentry);
         else
-                mnt = nfs_do_submount(path->mnt, path->dentry, fh, fattr);
+                mnt = nfs_do_submount(path->mnt->mnt_sb, path->dentry, fh, fattr);
         if (IS_ERR(mnt))
                 goto out;
 
@@ -209,19 +230,19 @@ static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
 
 /**
  * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
- * @mnt_parent - mountpoint of parent directory
+ * @sb - superblock of parent directory
  * @dentry - parent directory
  * @fh - filehandle for new root dentry
  * @fattr - attributes for new root inode
  *
  */
-static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
-                                        const struct dentry *dentry,
+static struct vfsmount *nfs_do_submount(struct super_block *sb,
+                                        struct dentry *dentry,
                                         struct nfs_fh *fh,
                                         struct nfs_fattr *fattr)
 {
         struct nfs_clone_mount mountdata = {
-                .sb = mnt_parent->mnt_sb,
+                .sb = sb,
                 .dentry = dentry,
                 .fh = fh,
                 .fattr = fattr,
@@ -237,11 +258,11 @@ static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
                         dentry->d_name.name);
         if (page == NULL)
                 goto out;
-        devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
+        devname = nfs_devname(dentry, page, PAGE_SIZE);
         mnt = (struct vfsmount *)devname;
         if (IS_ERR(devname))
                 goto free_page;
-        mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
+        mnt = nfs_do_clone_mount(NFS_SB(sb), devname, &mountdata);
 free_page:
         free_page((unsigned long)page);
 out: