raw-posix: Factor block size detection out of raw_probe_alignment()

Put it in new probe_logical_blocksize().
Signed-off-by: NEkaterina Tumanova <tumanova@linux.vnet.ibm.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1424087278-49393-3-git-send-email-tumanova@linux.vnet.ibm.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/raw-posix.c

@@ -218,39 +218,58 @@ static int raw_normalize_devicepath(const char **filename)
 }
 #endif
 
-static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
+/*
+ * Get logical block size via ioctl. On success store it in @sector_size_p.
+ */
+static int probe_logical_blocksize(int fd, unsigned int *sector_size_p)
 {
-    BDRVRawState *s = bs->opaque;
-    char *buf;
     unsigned int sector_size;
+    bool success = false;
 
-    /* For /dev/sg devices the alignment is not really used.
-       With buffered I/O, we don't have any restrictions. */
-    if (bs->sg || !s->needs_alignment) {
-        bs->request_alignment = 1;
-        s->buf_align = 1;
-        return;
-    }
+    errno = ENOTSUP;
 
     /* Try a few ioctls to get the right size */
-    bs->request_alignment = 0;
-    s->buf_align = 0;
-
 #ifdef BLKSSZGET
     if (ioctl(fd, BLKSSZGET, &sector_size) >= 0) {
-        bs->request_alignment = sector_size;
+        *sector_size_p = sector_size;
+        success = true;
     }
 #endif
 #ifdef DKIOCGETBLOCKSIZE
     if (ioctl(fd, DKIOCGETBLOCKSIZE, &sector_size) >= 0) {
-        bs->request_alignment = sector_size;
+        *sector_size_p = sector_size;
+        success = true;
     }
 #endif
 #ifdef DIOCGSECTORSIZE
     if (ioctl(fd, DIOCGSECTORSIZE, &sector_size) >= 0) {
-        bs->request_alignment = sector_size;
+        *sector_size_p = sector_size;
+        success = true;
     }
 #endif
+
+    return success ? 0 : -errno;
+}
+
+static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
+{
+    BDRVRawState *s = bs->opaque;
+    char *buf;
+
+    /* For /dev/sg devices the alignment is not really used.
+       With buffered I/O, we don't have any restrictions. */
+    if (bs->sg || !s->needs_alignment) {
+        bs->request_alignment = 1;
+        s->buf_align = 1;
+        return;
+    }
+
+    bs->request_alignment = 0;
+    s->buf_align = 0;
+    /* Let's try to use the logical blocksize for the alignment. */
+    if (probe_logical_blocksize(fd, &bs->request_alignment) < 0) {
+        bs->request_alignment = 0;
+    }
 #ifdef CONFIG_XFS
     if (s->is_xfs) {
         struct dioattr da;