1 files changed, 40 insertions, 18 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index fcd97b783fa1..3b1bd469accd 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -669,38 +669,59 @@ struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
         return inode;
 }
 
+/*
+ * Does overlay inode need to be hashed by lower inode?
+ */
+static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
+                             struct dentry *lower, struct dentry *index)
+{
+        struct ovl_fs *ofs = sb->s_fs_info;
+
+        /* No, if pure upper */
+        if (!lower)
+                return false;
+
+        /* Yes, if already indexed */
+        if (index)
+                return true;
+
+        /* Yes, if won't be copied up */
+        if (!ofs->upper_mnt)
+                return true;
+
+        /* No, if lower hardlink is or will be broken on copy up */
+        if ((upper || !ovl_indexdir(sb)) &&
+            !d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
+                return false;
+
+        /* No, if non-indexed upper with NFS export */
+        if (sb->s_export_op && upper)
+                return false;
+
+        /* Otherwise, hash by lower inode for fsnotify */
+        return true;
+}
+
 struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
                             struct dentry *lowerdentry, struct dentry *index,
                             unsigned int numlower)
 {
-        struct ovl_fs *ofs = sb->s_fs_info;
         struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
         struct inode *inode;
-        /* Already indexed or could be indexed on copy up? */
-        bool indexed = (index || (ovl_indexdir(sb) && !upperdentry));
-        struct dentry *origin = indexed ? lowerdentry : NULL;
+        bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index);
         bool is_dir;
 
-        if (WARN_ON(upperdentry && indexed && !lowerdentry))
-                return ERR_PTR(-EIO);
-
         if (!realinode)
                 realinode = d_inode(lowerdentry);
 
         /*
-         * Copy up origin (lower) may exist for non-indexed non-dir upper, but
-         * we must not use lower as hash key in that case.
-         * Hash non-dir that is or could be indexed by origin inode.
-         * Hash dir that is or could be merged by origin inode.
-         * Hash pure upper and non-indexed non-dir by upper inode.
-         * Hash non-indexed dir by upper inode for NFS export.
+         * Copy up origin (lower) may exist for non-indexed upper, but we must
+         * not use lower as hash key if this is a broken hardlink.
          */
         is_dir = S_ISDIR(realinode->i_mode);
-        if (is_dir && (indexed || !sb->s_export_op || !ofs->upper_mnt))
-                origin = lowerdentry;
-
-        if (upperdentry || origin) {
-                struct inode *key = d_inode(origin ?: upperdentry);
+        if (upperdentry || bylower) {
+                struct inode *key = d_inode(bylower ? lowerdentry :
+                                                      upperdentry);
                 unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
 
                 inode = iget5_locked(sb, (unsigned long) key,
@@ -728,6 +749,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
                         nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);
                 set_nlink(inode, nlink);
         } else {
+                /* Lower hardlink that will be broken on copy up */
                 inode = new_inode(sb);
                 if (!inode)
                         goto out_nomem;