[Qemu-devel] [PATCH v2] block/gluster: defend on legacy ftruncate api use

[Niels de Vos <ndevos@redhat.com>]

From: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

New versions of Glusters libgfapi.so have an updated glfs_ftruncate()
function that returns additional 'struct stat' structures to enable
advanced caching of attributes. This is useful for file servers, not so
much for QEMU. Never the less, the API has changed and needs to be
adopted.

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Signed-off-by: Niels de Vos <ndevos@redhat.com>

--
v2: do a compile check as suggested by Eric Blake
---
 block/gluster.c | 15 +++++++++++++--
 configure       | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/block/gluster.c b/block/gluster.c
index 4fd55a9cc5..d1c6f81f5c 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -997,6 +997,7 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
                                     PreallocMode prealloc, Error **errp)
 {
     int64_t current_length;
+    int ret;
 
     current_length = glfs_lseek(fd, 0, SEEK_END);
     if (current_length < 0) {
@@ -1024,7 +1025,12 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
 #endif /* CONFIG_GLUSTERFS_FALLOCATE */
 #ifdef CONFIG_GLUSTERFS_ZEROFILL
     case PREALLOC_MODE_FULL:
-        if (glfs_ftruncate(fd, offset)) {
+#ifdef CONFIG_GLUSTERFS_LEGACY_FTRUNCATE
+        ret = glfs_ftruncate(fd, offset);
+#else
+        ret = glfs_ftruncate(fd, offset, NULL, NULL);
+#endif
+        if (ret) {
             error_setg_errno(errp, errno, "Could not resize file");
             return -errno;
         }
@@ -1035,7 +1041,12 @@ static int qemu_gluster_do_truncate(struct glfs_fd *fd, int64_t offset,
         break;
 #endif /* CONFIG_GLUSTERFS_ZEROFILL */
     case PREALLOC_MODE_OFF:
-        if (glfs_ftruncate(fd, offset)) {
+#ifdef CONFIG_GLUSTERFS_LEGACY_FTRUNCATE
+        ret = glfs_ftruncate(fd, offset);
+#else
+        ret = glfs_ftruncate(fd, offset, NULL, NULL);
+#endif
+        if (ret) {
             error_setg_errno(errp, errno, "Could not resize file");
             return -errno;
         }
diff --git a/configure b/configure
index 2a7796ea80..f3c0918d6b 100755
--- a/configure
+++ b/configure
@@ -451,6 +451,7 @@ glusterfs_xlator_opt="no"
 glusterfs_discard="no"
 glusterfs_fallocate="no"
 glusterfs_zerofill="no"
+glusterfs_legacy_ftruncate="no"
 gtk=""
 gtkabi=""
 gtk_gl="no"
@@ -3947,6 +3948,19 @@ if test "$glusterfs" != "no" ; then
       glusterfs_fallocate="yes"
       glusterfs_zerofill="yes"
     fi
+    cat > $TMPC << EOF
+#include <glusterfs/api/glfs.h>
+
+int
+main(void)
+{
+	/* new glfs_ftruncate() passes two additional args */
+	return glfs_ftruncate(NULL, 0 /*, NULL, NULL */);
+}
+EOF
+    if compile_prog "$glusterfs_cflags" "$glusterfs_libs" ; then
+      glusterfs_legacy_ftruncate="yes"
+    fi
   else
     if test "$glusterfs" = "yes" ; then
       feature_not_found "GlusterFS backend support" \
@@ -6644,6 +6658,10 @@ if test "$glusterfs_zerofill" = "yes" ; then
   echo "CONFIG_GLUSTERFS_ZEROFILL=y" >> $config_host_mak
 fi
 
+if test "$glusterfs_legacy_ftruncate" = "yes" ; then
+  echo "CONFIG_GLUSTERFS_LEGACY_FTRUNCATE=y" >> $config_host_mak
+fi
+
 if test "$libssh2" = "yes" ; then
   echo "CONFIG_LIBSSH2=m" >> $config_host_mak
   echo "LIBSSH2_CFLAGS=$libssh2_cflags" >> $config_host_mak
-- 
2.17.1