1 files changed, 145 insertions, 0 deletions
diff --git a/fs/xfs/scrub/blob.c b/fs/xfs/scrub/blob.c
new file mode 100644
index 000000000000..94912fcb1fd1
--- /dev/null
+++ b/fs/xfs/scrub/blob.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "scrub/array.h"
+#include "scrub/blob.h"
+#include "scrub/xfile.h"
+
+/*
+ * XFS Blob Storage
+ * ================
+ * Stores and retrieves blobs using a memfd object.  Objects are appended to
+ * the file and the offset is returned as a magic cookie for retrieval.
+ */
+
+#define XB_KEY_MAGIC	0xABAADDAD
+struct xb_key {
+	uint32_t		magic;
+	uint32_t		size;
+	loff_t			offset;
+	/* blob comes after here */
+} __packed;
+
+/* Initialize a blob storage object. */
+struct xblob *
+xblob_init(void)
+{
+	struct xblob	*blob;
+	struct file	*filp;
+	int		error;
+
+	filp = xfile_create("blob storage");
+	if (!filp)
+		return ERR_PTR(-ENOMEM);
+	if (IS_ERR(filp))
+		return ERR_CAST(filp);
+
+	error = -ENOMEM;
+	blob = kmem_alloc(sizeof(struct xblob), KM_NOFS | KM_MAYFAIL);
+	if (!blob)
+		goto out_filp;
+
+	blob->filp = filp;
+	blob->last_offset = PAGE_SIZE;
+	return blob;
+out_filp:
+	fput(filp);
+	return ERR_PTR(error);
+}
+
+/* Destroy a blob storage object. */
+void
+xblob_destroy(
+	struct xblob	*blob)
+{
+	xfile_destroy(blob->filp);
+	kmem_free(blob);
+}
+
+/* Retrieve a blob. */
+int
+xblob_get(
+	struct xblob	*blob,
+	xblob_cookie	cookie,
+	void		*ptr,
+	uint32_t	size)
+{
+	struct xb_key	key;
+	loff_t		pos = cookie;
+	int		error;
+
+	error = xfile_io(blob->filp, XFILE_IO_READ, &pos, &key, sizeof(key));
+	if (error)
+		return error;
+
+	if (key.magic != XB_KEY_MAGIC || key.offset != cookie) {
+		ASSERT(0);
+		return -ENODATA;
+	}
+	if (size < key.size) {
+		ASSERT(0);
+		return -EFBIG;
+	}
+
+	return xfile_io(blob->filp, XFILE_IO_READ, &pos, ptr, key.size);
+}
+
+/* Store a blob. */
+int
+xblob_put(
+	struct xblob	*blob,
+	xblob_cookie	*cookie,
+	void		*ptr,
+	uint32_t	size)
+{
+	struct xb_key	key = {
+		.offset = blob->last_offset,
+		.magic = XB_KEY_MAGIC,
+		.size = size,
+	};
+	loff_t		pos = blob->last_offset;
+	int		error;
+
+	error = xfile_io(blob->filp, XFILE_IO_WRITE, &pos, &key, sizeof(key));
+	if (error)
+		goto out_err;
+
+	error = xfile_io(blob->filp, XFILE_IO_WRITE, &pos, ptr, size);
+	if (error)
+		goto out_err;
+
+	*cookie = blob->last_offset;
+	blob->last_offset = pos;
+	return 0;
+out_err:
+	xfile_discard(blob->filp, blob->last_offset, pos - 1);
+	return -ENOMEM;
+}
+
+/* Free a blob. */
+int
+xblob_free(
+	struct xblob	*blob,
+	xblob_cookie	cookie)
+{
+	struct xb_key	key;
+	loff_t		pos = cookie;
+	int		error;
+
+	error = xfile_io(blob->filp, XFILE_IO_READ, &pos, &key, sizeof(key));
+	if (error)
+		return error;
+
+	if (key.magic != XB_KEY_MAGIC || key.offset != cookie) {
+		ASSERT(0);
+		return -ENODATA;
+	}
+
+	xfile_discard(blob->filp, cookie, cookie + sizeof(key) + key.size - 1);
+	return 0;
+}