[dm-devel] [PATCH 01/30] kpartx: dasd: fix -Waddress-of-packed-member warning from gcc9

[Martin Wilck]

Fixes the following warning:

dasd.c: In function ‘read_dasd_pt’:
dasd.c:206:3: warning: converting a packed ‘volume_label_t’ {aka ‘struct
volume_label’} pointer (alignment 1) to a ‘label_ints_t’ {aka ‘unsigned int’}
pointer (alignment 4) may result in an unaligned pointer value
[-Waddress-of-packed-member]
  206 |   label_ints_t *label = (label_ints_t *) &vlabel;
      |   ^~~~~~~~~~~~

As volume_label_t is only used in read_dasd_pt(), and filled with memcpy(),
increasing its alignment should be safe.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 kpartx/dasd.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kpartx/dasd.h b/kpartx/dasd.h
index 749af49a..8ad5d620 100644
--- a/kpartx/dasd.h
+++ b/kpartx/dasd.h
@@ -68,7 +68,7 @@ typedef struct volume_label
 	char res3[28];	        /* reserved                                  */
 	uint8_t ldl_version;    /* version number, valid for ldl format      */
 	uint64_t formatted_blocks; /* valid when ldl_version >= f2           */
-} __attribute__ ((packed)) volume_label_t;
+} __attribute__ ((packed, aligned(__alignof__(int)))) volume_label_t;
 
 
 typedef struct extent
-- 
2.21.0