Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull shmem rename fixes from Al Viro:
 "A couple of shmem rename fixes - recent regression from tree-in-dcache
  series and older breakage from stable directory offsets stuff"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  shmem: fix recovery on rename failures
  shmem_whiteout(): fix regression from tree-in-dcache series

1 files changed, 21 insertions, 29 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 9264523be85c..591eb649ebba 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -346,22 +346,22 @@ void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry)
  * User space expects the directory offset value of the replaced
  * (new) directory entry to be unchanged after a rename.
  *
- * Returns zero on success, a negative errno value on failure.
+ * Caller must have grabbed a slot for new_dentry in the maple_tree
+ * associated with new_dir, even if dentry is negative.
  */
-int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
-			 struct inode *new_dir, struct dentry *new_dentry)
+void simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
+			  struct inode *new_dir, struct dentry *new_dentry)
 {
 	struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
 	struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
 	long new_offset = dentry2offset(new_dentry);
 
-	simple_offset_remove(old_ctx, old_dentry);
+	if (WARN_ON(!new_offset))
+		return;
 
-	if (new_offset) {
-		offset_set(new_dentry, 0);
-		return simple_offset_replace(new_ctx, old_dentry, new_offset);
-	}
-	return simple_offset_add(new_ctx, old_dentry);
+	simple_offset_remove(old_ctx, old_dentry);
+	offset_set(new_dentry, 0);
+	WARN_ON(simple_offset_replace(new_ctx, old_dentry, new_offset));
 }
 
 /**
@@ -388,31 +388,23 @@ int simple_offset_rename_exchange(struct inode *old_dir,
 	long new_index = dentry2offset(new_dentry);
 	int ret;
 
-	simple_offset_remove(old_ctx, old_dentry);
-	simple_offset_remove(new_ctx, new_dentry);
+	if (WARN_ON(!old_index || !new_index))
+		return -EINVAL;
 
-	ret = simple_offset_replace(new_ctx, old_dentry, new_index);
-	if (ret)
-		goto out_restore;
+	ret = mtree_store(&new_ctx->mt, new_index, old_dentry, GFP_KERNEL);
+	if (WARN_ON(ret))
+		return ret;
 
-	ret = simple_offset_replace(old_ctx, new_dentry, old_index);
-	if (ret) {
-		simple_offset_remove(new_ctx, old_dentry);
-		goto out_restore;
+	ret = mtree_store(&old_ctx->mt, old_index, new_dentry, GFP_KERNEL);
+	if (WARN_ON(ret)) {
+		mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL);
+		return ret;
 	}
 
-	ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
-	if (ret) {
-		simple_offset_remove(new_ctx, old_dentry);
-		simple_offset_remove(old_ctx, new_dentry);
-		goto out_restore;
-	}
+	offset_set(old_dentry, new_index);
+	offset_set(new_dentry, old_index);
+	simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
 	return 0;
-
-out_restore:
-	(void)simple_offset_replace(old_ctx, old_dentry, old_index);
-	(void)simple_offset_replace(new_ctx, new_dentry, new_index);
-	return ret;
 }
 
 /**