md: override md superblock recovery_offset for journal device
Journal device stores data in a log structure. We need record the log
start. Here we override md superblock recovery_offset for this purpose.
This field of a journal device is meaningless otherwise.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index eaaab52..a5f54ff 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -258,7 +258,10 @@
__le64 data_offset; /* sector start of data, often 0 */
__le64 data_size; /* sectors in this device that can be used for data */
__le64 super_offset; /* sector start of this superblock */
- __le64 recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
+ union {
+ __le64 recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
+ __le64 journal_tail;/* journal tail of journal device (from data_offset) */
+ };
__le32 dev_number; /* permanent identifier of this device - not role in raid */
__le32 cnt_corrected_read; /* number of read errors that were corrected by re-writing */
__u8 device_uuid[16]; /* user-space setable, ignored by kernel */