1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/raid/raid10.h b/include/linux/raid/raid10.h
index dfa528385e3..b1103298a8c 100644
--- a/include/linux/raid/raid10.h
+++ b/include/linux/raid/raid10.h
@@ -104,6 +104,13 @@ struct r10bio_s {
         } devs[0];
 };
 
+/* when we get a read error on a read-only array, we redirect to another
+ * device without failing the first device, or trying to over-write to
+ * correct the read error.  To keep track of bad blocks on a per-bio
+ * level, we store IO_BLOCKED in the appropriate 'bios' pointer
+ */
+#define IO_BLOCKED ((struct bio*)1)
+
 /* bits for r10bio.state */
 #define R10BIO_Uptodate 0
 #define R10BIO_IsSync   1