[libvirt] [PATCH 3/3] storage: Allow --shrink for raw type volume of fs pool

[Osier Yang]

There is no need to use posix_fallocate or SYS_fallocate to shrink
the volume, ftruncate can do the work. qemu-img/kvm-img supports to
shrink the volume itself.
---
 src/storage/storage_backend_fs.c | 7 +++++--
 src/util/virstoragefile.c        | 5 +++--
 src/util/virstoragefile.h        | 3 ++-
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index 78f5d53..cdfa66f 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -1245,13 +1245,16 @@ virStorageBackendFileSystemVolResize(virConnectPtr conn ATTRIBUTE_UNUSED,
                                      unsigned long long capacity,
                                      unsigned int flags)
 {
-    virCheckFlags(VIR_STORAGE_VOL_RESIZE_ALLOCATE, -1);
+    virCheckFlags(VIR_STORAGE_VOL_RESIZE_ALLOCATE |
+                  VIR_STORAGE_VOL_RESIZE_SHRINK, -1);
 
     bool pre_allocate = flags & VIR_STORAGE_VOL_RESIZE_ALLOCATE;
+    bool shrink = flags & VIR_STORAGE_VOL_RESIZE_SHRINK;
 
     if (vol->target.format == VIR_STORAGE_FILE_RAW) {
         return virStorageFileResize(vol->target.path, capacity,
-                                    vol->capacity, pre_allocate);
+                                    vol->capacity, pre_allocate,
+                                    shrink);
     } else {
         if (pre_allocate) {
             virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index e42eb77..25614df 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -1044,7 +1044,8 @@ int
 virStorageFileResize(const char *path,
                      unsigned long long capacity,
                      unsigned long long orig_capacity,
-                     bool pre_allocate)
+                     bool pre_allocate,
+                     bool shrink)
 {
     int fd = -1;
     int ret = -1;
@@ -1057,7 +1058,7 @@ virStorageFileResize(const char *path,
         goto cleanup;
     }
 
-    if (pre_allocate) {
+    if (pre_allocate && !shrink) {
 #if HAVE_POSIX_FALLOCATE
         if ((rc = posix_fallocate(fd, offset, len)) != 0) {
             virReportSystemError(rc,
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index c195c9a..46fe9ba 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -92,7 +92,8 @@ void virStorageFileFreeMetadata(virStorageFileMetadataPtr meta);
 int virStorageFileResize(const char *path,
                          unsigned long long capacity,
                          unsigned long long orig_capacity,
-                         bool pre_allocate);
+                         bool pre_allocate,
+                         bool shrink);
 
 enum {
     VIR_STORAGE_FILE_SHFS_NFS = (1 << 0),
-- 
1.8.1.4