block: add gluster ifdef guard checks for SEEK_DATA/SEEK_HOLE support

Add checks to see if the system compiling QEMU has support for
SEEK_HOLE/SEEK_DATA.  If the system does not, we will flag that seek
data is unsupported in gluster.

Note: this is not a check on whether the gluster server itself supports
SEEK_DATA (that is already done during runtime), but rather if the
compilation environment supports SEEK_DATA.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-id: 00370bce5c98140d6c56ad5145635ec6551265cc.1475876377.git.jcody@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>

diff --git a/block/gluster.c b/block/gluster.c
index af76d7d..1735d12 100644 (file)
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -668,7 +668,10 @@ static void qemu_gluster_parse_flags(int bdrv_flags, int *open_flags)
  */
 static bool qemu_gluster_test_seek(struct glfs_fd *fd)
 {
-    off_t ret, eof;
+    off_t ret = 0;
+
+#if defined SEEK_HOLE && defined SEEK_DATA
+    off_t eof;
 
     eof = glfs_lseek(fd, 0, SEEK_END);
     if (eof < 0) {
@@ -678,6 +681,8 @@ static bool qemu_gluster_test_seek(struct glfs_fd *fd)
 
     /* this should always fail with ENXIO if SEEK_DATA is supported */
     ret = glfs_lseek(fd, eof, SEEK_DATA);
+#endif
+
     return (ret < 0) && (errno == ENXIO);
 }
 
@@ -1178,12 +1183,14 @@ static int find_allocation(BlockDriverState *bs, off_t start,
                            off_t *data, off_t *hole)
 {
     BDRVGlusterState *s = bs->opaque;
-    off_t offs;
 
     if (!s->supports_seek_data) {
-        return -ENOTSUP;
+        goto exit;
     }
 
+#if defined SEEK_HOLE && defined SEEK_DATA
+    off_t offs;
+
     /*
      * SEEK_DATA cases:
      * D1. offs == start: start is in data
@@ -1247,6 +1254,10 @@ static int find_allocation(BlockDriverState *bs, off_t start,
 
     /* D1 and H1 */
     return -EBUSY;
+#endif
+
+exit:
+    return -ENOTSUP;
 }
 
 /*