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>

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 796d06f..e9d4013 100644 (file)
--- 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 50dc214..bc6d261 100644 (file)
--- 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;
 }