ovl: enumerate private xattrs

Instead of passing the xattr name down to the ovl_do_*xattr() accessor
functions, pass an enumerated value.  The enum can use the same names as
the the previous #define for each xattr name.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/namei.c

@@ -106,12 +106,12 @@ int ovl_check_fb_len(struct ovl_fb *fb, int fb_len)
 }
 
 static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
-				 const char *name)
+				 enum ovl_xattr ox)
 {
 	int res, err;
 	struct ovl_fh *fh = NULL;
 
-	res = ovl_do_getxattr(ofs, dentry, name, NULL, 0);
+	res = ovl_do_getxattr(ofs, dentry, ox, NULL, 0);
 	if (res < 0) {
 		if (res == -ENODATA || res == -EOPNOTSUPP)
 			return NULL;
@@ -125,7 +125,7 @@ static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry,
 	if (!fh)
 		return ERR_PTR(-ENOMEM);
 
-	res = ovl_do_getxattr(ofs, dentry, name, fh->buf, res);
+	res = ovl_do_getxattr(ofs, dentry, ox, fh->buf, res);
 	if (res < 0)
 		goto fail;
 
@@ -416,9 +416,9 @@ static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
  * Return 0 on match, -ESTALE on mismatch, < 0 on error.
  */
 static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
-			 const char *name, const struct ovl_fh *fh)
+			 enum ovl_xattr ox, const struct ovl_fh *fh)
 {
-	struct ovl_fh *ofh = ovl_get_fh(ofs, dentry, name);
+	struct ovl_fh *ofh = ovl_get_fh(ofs, dentry, ox);
 	int err = 0;
 
 	if (!ofh)
@@ -443,7 +443,7 @@ static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry,
  * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
  */
 int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
-		      const char *name, struct dentry *real, bool is_upper,
+		      enum ovl_xattr ox, struct dentry *real, bool is_upper,
 		      bool set)
 {
 	struct inode *inode;
@@ -457,9 +457,9 @@ int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
 		goto fail;
 	}
 
-	err = ovl_verify_fh(ofs, dentry, name, fh);
+	err = ovl_verify_fh(ofs, dentry, ox, fh);
 	if (set && err == -ENODATA)
-		err = ovl_do_setxattr(ofs, dentry, name, fh->buf, fh->fb.len);
+		err = ovl_do_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len);
 	if (err)
 		goto fail;
 

fs/overlayfs/overlayfs.h

@@ -23,13 +23,16 @@ enum ovl_path_type {
 #define OVL_TYPE_ORIGIN(type)	((type) & __OVL_PATH_ORIGIN)
 
 #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
-#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
-#define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
-#define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
-#define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
-#define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
-#define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
-#define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
+
+enum ovl_xattr {
+	OVL_XATTR_OPAQUE,
+	OVL_XATTR_REDIRECT,
+	OVL_XATTR_ORIGIN,
+	OVL_XATTR_IMPURE,
+	OVL_XATTR_NLINK,
+	OVL_XATTR_UPPER,
+	OVL_XATTR_METACOPY,
+};
 
 enum ovl_inode_flag {
 	/* Pure upper dir that may contain non pure upper entries */
@@ -110,6 +113,12 @@ struct ovl_fh {
 #define OVL_FH_FID_OFFSET	(OVL_FH_WIRE_OFFSET + \
 				 offsetof(struct ovl_fb, fid))
 
+extern const char *ovl_xattr_table[];
+static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
+{
+	return ovl_xattr_table[ox];
+}
+
 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	int err = vfs_rmdir(dir, dentry);
@@ -171,16 +180,18 @@ static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
 }
 
 static inline ssize_t ovl_do_getxattr(struct ovl_fs *ofs, struct dentry *dentry,
-				      const char *name, void *value,
+				      enum ovl_xattr ox, void *value,
 				      size_t size)
 {
+	const char *name = ovl_xattr(ofs, ox);
 	return vfs_getxattr(dentry, name, value, size);
 }
 
 static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
-				  const char *name, const void *value,
+				  enum ovl_xattr ox, const void *value,
 				  size_t size)
 {
+	const char *name = ovl_xattr(ofs, ox);
 	int err = vfs_setxattr(dentry, name, value, size, 0);
 	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0) = %i\n",
 		 dentry, name, min((int)size, 48), value, size, err);
@@ -188,8 +199,9 @@ static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
 }
 
 static inline int ovl_do_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
-				     const char *name)
+				     enum ovl_xattr ox)
 {
+	const char *name = ovl_xattr(ofs, ox);
 	int err = vfs_removexattr(dentry, name);
 	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
 	return err;
@@ -291,9 +303,9 @@ void ovl_copy_up_end(struct dentry *dentry);
 bool ovl_already_copied_up(struct dentry *dentry, int flags);
 bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry);
 bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
-			 const char *name);
+			 enum ovl_xattr ox);
 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
-		       const char *name, const void *value, size_t size,
+		       enum ovl_xattr ox, const void *value, size_t size,
 		       int xerr);
 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
 void ovl_set_flag(unsigned long flag, struct inode *inode);
@@ -376,7 +388,7 @@ struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 			struct dentry *upperdentry, struct ovl_path **stackp);
 int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
-		      const char *name, struct dentry *real, bool is_upper,
+		      enum ovl_xattr ox, struct dentry *real, bool is_upper,
 		      bool set);
 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);

fs/overlayfs/util.c

@@ -558,7 +558,7 @@ bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry)
 }
 
 bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
-			 const char *name)
+			 enum ovl_xattr ox)
 {
 	int res;
 	char val;
@@ -566,15 +566,36 @@ bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
 	if (!d_is_dir(dentry))
 		return false;
 
-	res = ovl_do_getxattr(OVL_FS(sb), dentry, name, &val, 1);
+	res = ovl_do_getxattr(OVL_FS(sb), dentry, ox, &val, 1);
 	if (res == 1 && val == 'y')
 		return true;
 
 	return false;
 }
 
+#define OVL_XATTR_OPAQUE_POSTFIX	"opaque"
+#define OVL_XATTR_REDIRECT_POSTFIX	"redirect"
+#define OVL_XATTR_ORIGIN_POSTFIX	"origin"
+#define OVL_XATTR_IMPURE_POSTFIX	"impure"
+#define OVL_XATTR_NLINK_POSTFIX		"nlink"
+#define OVL_XATTR_UPPER_POSTFIX		"upper"
+#define OVL_XATTR_METACOPY_POSTFIX	"metacopy"
+
+#define OVL_XATTR_TAB_ENTRY(x) \
+	[x] = OVL_XATTR_PREFIX x ## _POSTFIX
+
+const char *ovl_xattr_table[] = {
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
+};
+
 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
-		       const char *name, const void *value, size_t size,
+		       enum ovl_xattr ox, const void *value, size_t size,
 		       int xerr)
 {
 	int err;
@@ -583,10 +604,10 @@ int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
 	if (ofs->noxattr)
 		return xerr;
 
-	err = ovl_do_setxattr(ofs, upperdentry, name, value, size);
+	err = ovl_do_setxattr(ofs, upperdentry, ox, value, size);
 
 	if (err == -EOPNOTSUPP) {
-		pr_warn("cannot set %s xattr on upper\n", name);
+		pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
 		ofs->noxattr = true;
 		return xerr;
 	}