[Ocfs2-devel] [PATCH 1/2] Ocfs2: Add new ioctls prototype and corresponding data structure to ocfs2 header.

[Tristan Ye]

We use OCFS2_IOC_INFO to manipulate the new ioctl, the requests can
be stored in a array of (struct ocfs2_info_request), which should be
NULL-terminated, kernel therefore can recoginze and fill them one by
one.

The reason why we need these ioctls is to offer the none-privileged
end-user a possibility to get filesys info gathering.

Idea here is to make the spearated request small enough to guarantee
a better backward&forward compatibility since a small piece of request
would be less likely to be broken if filesys on raw disk get changed.

Currently, the first version include following request type:

	OCFS2_INFO_CLUSTERSIZE,
	OCFS2_INFO_BLOCKSIZE,
	OCFS2_INFO_SLOTNUM,
	OCFS2_INFO_LABEL,
	OCFS2_INFO_UUID,
	OCFS2_INFO_FS_FEATURES

It may be grown from time to time:)

Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
---
 fs/ocfs2/ocfs2_fs.h |   69 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index e9431e4..dac7f4c 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -309,6 +309,75 @@ struct reflink_arguments {
 };
 #define OCFS2_IOC_REFLINK	_IOW('o', 4, struct reflink_arguments)
 
+#define OCFS2_UUID_LEN              16
+#define OCFS2_MAX_LABEL_LEN         64
+
+/*
+ * Used to query fs information for none-privileged 
+ * users by using OCFS2_IOC_INFO ioctols, a series of
+ * following requests need to be NULL-terminated.
+ *
+ * Always try to separate info request into small pieces to
+ * guarantee the backward&forward compatibility.
+ */
+struct ocfs2_info_request {
+	__u32 ir_code;	/* Info request code */
+	__u32 ir_flags; /* Request flags */
+};
+
+struct ocfs2_info_request_clustersize {
+	struct ocfs2_info_request ir_request;
+	__u32 ir_clustersize;
+};
+
+struct ocfs2_info_request_blocksize {
+	struct ocfs2_info_request ir_request;
+	__u32 ir_blocksize;
+};
+
+struct ocfs2_info_request_slotnum {
+	struct ocfs2_info_request ir_request;
+	__u16 ir_slotnum;
+};
+
+struct ocfs2_info_request_label {
+	struct ocfs2_info_request ir_request;
+	__u8	ir_label[OCFS2_MAX_LABEL_LEN];
+};
+
+struct ocfs2_info_request_uuid {
+	struct ocfs2_info_request ir_request;
+	__u8	ir_uuid[OCFS2_UUID_LEN];
+};
+
+struct ocfs2_info_request_fs_features {
+	struct ocfs2_info_request ir_quest;
+	__u32 ir_compat_features;
+	__u32 ir_incompat_features;
+	__u32 ir_ro_compat_features;
+};
+
+/* Codes for cfs2_info_request */
+
+#define OCFS2_INFO_CLUSTERSIZE	0x00000001
+#define OCFS2_INFO_BLOCKSIZE	0x00000002
+#define OCFS2_INFO_SLOTNUM      0x00000004
+#define OCFS2_INFO_LABEL        0x00000008
+#define OCFS2_INFO_UUID         0x00000010
+#define OCFS2_INFO_FS_FEATURES	0x00000020
+
+/* Flags for struct ocfs2_info_request */
+/* Filled by the caller */
+#define OCFS2_INFO_FL_NON_COHERENT  0x00000001  /* Cluster coherency not required.
+						   This is a hint.  It is up to
+						   ocfs2 whether the request can
+						   be fulfilled without locking. */
+/* Filled by ocfs2 */
+#define OCFS2_INFO_FL_FILLED        0x80000000  /* Filesystem understood this
+						   request and filled in the
+						   answer */
+
+#define OCFS2_IOC_INFO		_IOR('o', 5, struct ocfs2_info_request)
 
 /*
  * Journal Flags (ocfs2_dinode.id1.journal1.i_flags)
-- 
1.5.5