blockdev: add BLKDISCARDZEROES

Signed-off-by: Karel Zak <kzak@redhat.com>

disk-utils/blockdev.c

@@ -74,6 +74,12 @@ struct bdc bdcms[] =
 		.argtype = ARG_INT,
 		.argval = -1,
 		.help = N_("get read-only")
+	},{
+		IOCTL_ENTRY(BLKDISCARDZEROES),
+		.name = "--getdiscardzeroes",
+		.argtype = ARG_UINT,
+		.argval = -1,
+		.help = N_("get discard zeroes support status")
 	},{
 		IOCTL_ENTRY(BLKSSZGET),
 		.name = "--getss",

include/blkdev.h

@@ -33,6 +33,7 @@
 
 #endif /* BLKROSET && __linux__ */
 
+
 #ifdef APPLE_DARWIN
 #define BLKGETSIZE DKIOCGETBLOCKCOUNT32
 #endif
@@ -45,6 +46,11 @@
 #define BLKPBSZGET _IO(0x12,123)
 #endif
 
+/* discard zeroes support, introduced in 2.6.33 (commait 98262f27) */
+#ifndef BLKDISCARDZEROES
+#define BLKDISCARDZEROES _IO(0x12,124)
+#endif
+
 #ifndef FIFREEZE
 #define FIFREEZE   _IOWR('X', 119, int)    /* Freeze */
 #define FITHAW     _IOWR('X', 120, int)    /* Thaw */