Use posix_memalign() for memory used to write bitmaps

This makes super[01].c properly align buffers used for the bitmap
using posix_memalign() to make sure the writes don't fail in case the
bitmap is opened using O_DIRECT.

This is based on https://bugzilla.redhat.com/show_bug.cgi?id=789898
and an initial patch by Alexander Murashkin.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 5 insertions, 2 deletions

diff --git a/super1.c b/super1.c
index cfa237a0..a18952a7 100644
--- a/super1.c
+++ b/super1.c
@@ -1641,12 +1641,14 @@ static int write_bitmap1(struct supertype *st, int fd)
 	struct mdp_superblock_1 *sb = st->sb;
 	bitmap_super_t *bms = (bitmap_super_t*)(((char*)sb)+1024);
 	int rv = 0;
-
+	void *buf;
 	int towrite, n;
-	char buf[4096];
 
 	locate_bitmap1(st, fd);
 
+	if (posix_memalign(&buf, 4096, 4096))
+		return -ENOMEM;
+
 	memset(buf, 0xff, 4096);
 	memcpy(buf, ((char*)sb)+1024, sizeof(bitmap_super_t));
 
@@ -1669,6 +1671,7 @@ static int write_bitmap1(struct supertype *st, int fd)
 	if (towrite)
 		rv = -2;
 
+	free(buf);
 	return rv;
 }