[Qemu-block] [PATCH 1/1] block: add gluster ifdef guard checks for SEEK_DATA/SEEK_HOLE support

[Jeff Cody]

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.

Signed-off-by: Jeff Cody <address@hidden>
---

Note: this patch is untested on older systems that do not support SEEK_DATA
(e.g.. RHEL6).  This won't be pulled into my tree until it is verified.


 block/gluster.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/block/gluster.c b/block/gluster.c
index e7bd13c..acb1934 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -672,8 +672,10 @@ 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;
+    off_t eof;
 
+#if defined SEEK_HOLE && defined SEEK_DATA
     eof = glfs_lseek(fd, 0, SEEK_END);
     if (eof < 0) {
         /* this should never occur */
@@ -682,6 +684,7 @@ 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);
 }
 
@@ -1185,9 +1188,10 @@ static int find_allocation(BlockDriverState *bs, off_t 
start,
     off_t offs;
 
     if (!s->supports_seek_data) {
-        return -ENOTSUP;
+        goto exit;
     }
 
+#if defined SEEK_HOLE && defined SEEK_DATA
     /*
      * SEEK_DATA cases:
      * D1. offs == start: start is in data
@@ -1251,6 +1255,9 @@ static int find_allocation(BlockDriverState *bs, off_t 
start,
 
     /* D1 and H1 */
     return -EBUSY;
+#endif
+exit:
+    return -ENOTSUP;
 }
 
 /*
-- 
2.7.4