ovl: use vfs_get_link()

Resulting in a complete removal of a function basically implementing the
inverse of vfs_readlink().

As a bonus, now the proper security hook is also called.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

2 files changed, 7 insertions, 49 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 796d06fafd09..e9d4013ed3c6 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -177,40 +177,6 @@ out_fput:
         return error;
 }
 
-static char *ovl_read_symlink(struct dentry *realdentry)
-{
-        int res;
-        char *buf;
-        struct inode *inode = realdentry->d_inode;
-        mm_segment_t old_fs;
-
-        res = -EINVAL;
-        if (!inode->i_op->readlink)
-                goto err;
-
-        res = -ENOMEM;
-        buf = (char *) __get_free_page(GFP_KERNEL);
-        if (!buf)
-                goto err;
-
-        old_fs = get_fs();
-        set_fs(get_ds());
-        /* The cast to a user pointer is valid due to the set_fs() */
-        res = inode->i_op->readlink(realdentry,
-                                    (char __user *)buf, PAGE_SIZE - 1);
-        set_fs(old_fs);
-        if (res < 0) {
-                free_page((unsigned long) buf);
-                goto err;
-        }
-        buf[res] = '\0';
-
-        return buf;
-
-err:
-        return ERR_PTR(res);
-}
-
 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 {
         struct iattr attr = {
@@ -342,18 +308,20 @@ out_cleanup:
 int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                     struct path *lowerpath, struct kstat *stat)
 {
+        DEFINE_DELAYED_CALL(done);
         struct dentry *workdir = ovl_workdir(dentry);
         int err;
         struct kstat pstat;
         struct path parentpath;
+        struct dentry *lowerdentry = lowerpath->dentry;
         struct dentry *upperdir;
         struct dentry *upperdentry;
-        char *link = NULL;
+        const char *link = NULL;
 
         if (WARN_ON(!workdir))
                 return -EROFS;
 
-        ovl_do_check_copy_up(lowerpath->dentry);
+        ovl_do_check_copy_up(lowerdentry);
 
         ovl_path_upper(parent, &parentpath);
         upperdir = parentpath.dentry;
@@ -363,7 +331,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                 return err;
 
         if (S_ISLNK(stat->mode)) {
-                link = ovl_read_symlink(lowerpath->dentry);
+                link = vfs_get_link(lowerdentry, &done);
                 if (IS_ERR(link))
                         return PTR_ERR(link);
         }
@@ -388,9 +356,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
         }
 out_unlock:
         unlock_rename(workdir, upperdir);
-
-        if (link)
-                free_page((unsigned long) link);
+        do_delayed_call(&done);
 
         return err;
 }
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 50dc214c44f2..bc6d261db669 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -156,22 +156,14 @@ static const char *ovl_get_link(struct dentry *dentry,
                                 struct inode *inode,
                                 struct delayed_call *done)
 {
-        struct dentry *realdentry;
-        struct inode *realinode;
         const struct cred *old_cred;
         const char *p;
 
         if (!dentry)
                 return ERR_PTR(-ECHILD);
 
-        realdentry = ovl_dentry_real(dentry);
-        realinode = realdentry->d_inode;
-
-        if (WARN_ON(!realinode->i_op->get_link))
-                return ERR_PTR(-EPERM);
-
         old_cred = ovl_override_creds(dentry->d_sb);
-        p = realinode->i_op->get_link(realdentry, realinode, done);
+        p = vfs_get_link(ovl_dentry_real(dentry), done);
         revert_creds(old_cred);
         return p;
 }