ovl: make path-type a bitmap

OVL_PATH_PURE_UPPER -> __OVL_PATH_UPPER | __OVL_PATH_PURE
OVL_PATH_UPPER      -> __OVL_PATH_UPPER
OVL_PATH_MERGE      -> __OVL_PATH_UPPER | __OVL_PATH_MERGE
OVL_PATH_LOWER      -> 0

Multiple R/O layers will allow __OVL_PATH_MERGE without __OVL_PATH_UPPER.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

6 files changed, 41 insertions, 36 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index ea10a8719107..a5bfd60f4f6f 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -385,7 +385,7 @@ int ovl_copy_up(struct dentry *dentry)
                 struct kstat stat;
                 enum ovl_path_type type = ovl_path_type(dentry);
 
-                if (type != OVL_PATH_LOWER)
+                if (OVL_TYPE_UPPER(type))
                         break;
 
                 next = dget(dentry);
@@ -394,7 +394,7 @@ int ovl_copy_up(struct dentry *dentry)
                         parent = dget_parent(next);
 
                         type = ovl_path_type(parent);
-                        if (type != OVL_PATH_LOWER)
+                        if (OVL_TYPE_UPPER(type))
                                 break;
 
                         dput(next);
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 8ffc4b980f1b..ab50bd111feb 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -152,7 +152,7 @@ static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
          * correct link count.  nlink=1 seems to pacify 'find' and
          * other utilities.
          */
-        if (type == OVL_PATH_MERGE)
+        if (OVL_TYPE_MERGE(type))
                 stat->nlink = 1;
 
         return 0;
@@ -630,7 +630,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
                 goto out_drop_write;
 
         type = ovl_path_type(dentry);
-        if (type == OVL_PATH_PURE_UPPER) {
+        if (OVL_TYPE_PURE_UPPER(type)) {
                 err = ovl_remove_upper(dentry, is_dir);
         } else {
                 const struct cred *old_cred;
@@ -712,7 +712,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
         /* Don't copy up directory trees */
         old_type = ovl_path_type(old);
         err = -EXDEV;
-        if ((old_type == OVL_PATH_LOWER || old_type == OVL_PATH_MERGE) && is_dir)
+        if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
                 goto out;
 
         if (new->d_inode) {
@@ -725,25 +725,25 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 
                 new_type = ovl_path_type(new);
                 err = -EXDEV;
-                if (!overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir)
+                if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
                         goto out;
 
                 err = 0;
-                if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
+                if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
                         if (ovl_dentry_lower(old)->d_inode ==
                             ovl_dentry_lower(new)->d_inode)
                                 goto out;
                 }
-                if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
+                if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
                         if (ovl_dentry_upper(old)->d_inode ==
                             ovl_dentry_upper(new)->d_inode)
                                 goto out;
                 }
         } else {
                 if (ovl_dentry_is_opaque(new))
-                        new_type = OVL_PATH_UPPER;
+                        new_type = __OVL_PATH_UPPER;
                 else
-                        new_type = OVL_PATH_PURE_UPPER;
+                        new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
         }
 
         err = ovl_want_write(old);
@@ -763,8 +763,8 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
                         goto out_drop_write;
         }
 
-        old_opaque = old_type != OVL_PATH_PURE_UPPER;
-        new_opaque = new_type != OVL_PATH_PURE_UPPER;
+        old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
+        new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 
         if (old_opaque || new_opaque) {
                 err = -ENOMEM;
@@ -787,7 +787,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
                 old_cred = override_creds(override_cred);
         }
 
-        if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) {
+        if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
                 opaquedir = ovl_check_empty_and_clear(new);
                 err = PTR_ERR(opaquedir);
                 if (IS_ERR(opaquedir)) {
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 07d74b24913b..48492f1240ad 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -238,7 +238,10 @@ out:
 static bool ovl_need_xattr_filter(struct dentry *dentry,
                                   enum ovl_path_type type)
 {
-        return type == OVL_PATH_UPPER && S_ISDIR(dentry->d_inode->i_mode);
+        if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER)
+                return S_ISDIR(dentry->d_inode->i_mode);
+        else
+                return false;
 }
 
 ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
@@ -299,7 +302,7 @@ int ovl_removexattr(struct dentry *dentry, const char *name)
         if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
                 goto out_drop_write;
 
-        if (type == OVL_PATH_LOWER) {
+        if (!OVL_TYPE_UPPER(type)) {
                 err = vfs_getxattr(realpath.dentry, name, NULL, 0);
                 if (err < 0)
                         goto out_drop_write;
@@ -321,7 +324,7 @@ out:
 static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
                                   struct dentry *realdentry)
 {
-        if (type != OVL_PATH_LOWER)
+        if (OVL_TYPE_UPPER(type))
                 return false;
 
         if (special_file(realdentry->d_inode->i_mode))
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 814bed33dd07..d39eaa8f5e47 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -12,12 +12,17 @@
 struct ovl_entry;
 
 enum ovl_path_type {
-        OVL_PATH_PURE_UPPER,
-        OVL_PATH_UPPER,
-        OVL_PATH_MERGE,
-        OVL_PATH_LOWER,
+        __OVL_PATH_PURE         = (1 << 0),
+        __OVL_PATH_UPPER        = (1 << 1),
+        __OVL_PATH_MERGE        = (1 << 2),
 };
 
+#define OVL_TYPE_UPPER(type)    ((type) & __OVL_PATH_UPPER)
+#define OVL_TYPE_MERGE(type)    ((type) & __OVL_PATH_MERGE)
+#define OVL_TYPE_PURE_UPPER(type) ((type) & __OVL_PATH_PURE)
+#define OVL_TYPE_MERGE_OR_LOWER(type) \
+        (OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type))
+
 extern const char *ovl_opaque_xattr;
 
 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 3efa44acf98b..481e44873b65 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -253,8 +253,8 @@ static void ovl_dir_reset(struct file *file)
                 ovl_cache_put(od, dentry);
                 od->cache = NULL;
         }
-        WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
-        if (od->is_real && type == OVL_PATH_MERGE)
+        WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type));
+        if (od->is_real && OVL_TYPE_MERGE(type))
                 od->is_real = false;
 }
 
@@ -429,7 +429,7 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
         /*
          * Need to check if we started out being a lower dir, but got copied up
          */
-        if (!od->is_upper && ovl_path_type(dentry) != OVL_PATH_LOWER) {
+        if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) {
                 struct inode *inode = file_inode(file);
 
                 realfile = lockless_dereference(od->upperfile);
@@ -495,8 +495,8 @@ static int ovl_dir_open(struct inode *inode, struct file *file)
         }
         INIT_LIST_HEAD(&od->cursor.l_node);
         od->realfile = realfile;
-        od->is_real = (type != OVL_PATH_MERGE);
-        od->is_upper = (type != OVL_PATH_LOWER);
+        od->is_real = !OVL_TYPE_MERGE(type);
+        od->is_upper = OVL_TYPE_UPPER(type);
         od->cursor.is_cursor = true;
         file->private_data = od;
 
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index f16d318b71f8..821719cc8537 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -64,22 +64,19 @@ const char *ovl_opaque_xattr = "trusted.overlay.opaque";
 enum ovl_path_type ovl_path_type(struct dentry *dentry)
 {
         struct ovl_entry *oe = dentry->d_fsdata;
+        enum ovl_path_type type = 0;
 
         if (oe->__upperdentry) {
+                type = __OVL_PATH_UPPER;
+
                 if (oe->lowerdentry) {
                         if (S_ISDIR(dentry->d_inode->i_mode))
-                                return OVL_PATH_MERGE;
-                        else
-                                return OVL_PATH_UPPER;
-                } else {
-                        if (oe->opaque)
-                                return OVL_PATH_UPPER;
-                        else
-                                return OVL_PATH_PURE_UPPER;
+                                type |= __OVL_PATH_MERGE;
+                } else if (!oe->opaque) {
+                        type |= __OVL_PATH_PURE;
                 }
-        } else {
-                return OVL_PATH_LOWER;
         }
+        return type;
 }
 
 static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
@@ -101,7 +98,7 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 
         enum ovl_path_type type = ovl_path_type(dentry);
 
-        if (type == OVL_PATH_LOWER)
+        if (!OVL_TYPE_UPPER(type))
                 ovl_path_lower(dentry, path);
         else
                 ovl_path_upper(dentry, path);