AFS: Use d_automount() rather than abusing follow_link()

Make AFS use the new d_automount() dentry operation rather than abusing
follow_link() on directories.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 19 insertions, 30 deletions

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index e6a4ab980e31..20c106f24927 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -66,6 +66,7 @@ const struct dentry_operations afs_fs_dentry_operations = {
         .d_revalidate   = afs_d_revalidate,
         .d_delete       = afs_d_delete,
         .d_release      = afs_d_release,
+        .d_automount    = afs_d_automount,
 };
 
 #define AFS_DIR_HASHTBL_SIZE    128
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 0747339011c3..db66c5201474 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -184,7 +184,8 @@ struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
         inode->i_generation     = 0;
 
         set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
-        inode->i_flags |= S_NOATIME;
+        set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+        inode->i_flags |= S_AUTOMOUNT | S_NOATIME;
         unlock_new_inode(inode);
         _leave(" = %p", inode);
         return inode;
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 58c633b80246..5a9b6843bac1 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -592,6 +592,7 @@ extern const struct inode_operations afs_mntpt_inode_operations;
 extern const struct inode_operations afs_autocell_inode_operations;
 extern const struct file_operations afs_mntpt_file_operations;
 
+extern struct vfsmount *afs_d_automount(struct path *);
 extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
 extern void afs_mntpt_kill_timer(void);
 
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index f3e891d57a2c..d23b2e344a78 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -24,7 +24,6 @@ static struct dentry *afs_mntpt_lookup(struct inode *dir,
                                        struct dentry *dentry,
                                        struct nameidata *nd);
 static int afs_mntpt_open(struct inode *inode, struct file *file);
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd);
 static void afs_mntpt_expiry_timed_out(struct work_struct *work);
 
 const struct file_operations afs_mntpt_file_operations = {
@@ -34,13 +33,11 @@ const struct file_operations afs_mntpt_file_operations = {
 
 const struct inode_operations afs_mntpt_inode_operations = {
         .lookup         = afs_mntpt_lookup,
-        .follow_link    = afs_mntpt_follow_link,
         .readlink       = page_readlink,
         .getattr        = afs_getattr,
 };
 
 const struct inode_operations afs_autocell_inode_operations = {
-        .follow_link    = afs_mntpt_follow_link,
         .getattr        = afs_getattr,
 };
 
@@ -88,6 +85,7 @@ int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
                 _debug("symlink is a mountpoint");
                 spin_lock(&vnode->lock);
                 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+                vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
                 spin_unlock(&vnode->lock);
         }
 
@@ -238,49 +236,37 @@ error_no_devname:
 }
 
 /*
- * follow a link from a mountpoint directory, thus causing it to be mounted
+ * handle an automount point
  */
-static void *afs_mntpt_follow_link(struct dentry *dentry, struct nameidata *nd)
+struct vfsmount *afs_d_automount(struct path *path)
 {
         struct vfsmount *newmnt;
         int err;
 
-        _enter("%p{%s},{%s:%p{%s},}",
-               dentry,
-               dentry->d_name.name,
-               nd->path.mnt->mnt_devname,
-               dentry,
-               nd->path.dentry->d_name.name);
-
-        dput(nd->path.dentry);
-        nd->path.dentry = dget(dentry);
+        _enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
 
-        newmnt = afs_mntpt_do_automount(nd->path.dentry);
-        if (IS_ERR(newmnt)) {
-                path_put(&nd->path);
-                return (void *)newmnt;
-        }
+        newmnt = afs_mntpt_do_automount(path->dentry);
+        if (IS_ERR(newmnt))
+                return newmnt;
 
         mntget(newmnt);
-        err = do_add_mount(newmnt, &nd->path, MNT_SHRINKABLE, &afs_vfsmounts);
+        err = do_add_mount(newmnt, path, MNT_SHRINKABLE, &afs_vfsmounts);
         switch (err) {
         case 0:
-                path_put(&nd->path);
-                nd->path.mnt = newmnt;
-                nd->path.dentry = dget(newmnt->mnt_root);
                 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
                                    afs_mntpt_expiry_timeout * HZ);
-                break;
+                _leave(" = %p {%s}", newmnt, newmnt->mnt_devname);
+                return newmnt;
         case -EBUSY:
                 /* someone else made a mount here whilst we were busy */
-                err = follow_down(&nd->path, false);
+                mntput(newmnt);
+                _leave(" = NULL [EBUSY]");
+                return NULL;
         default:
                 mntput(newmnt);
-                break;
+                _leave(" = %d", err);
+                return ERR_PTR(err);
         }
-
-        _leave(" = %d", err);
-        return ERR_PTR(err);
 }
 
 /*