block/file: Add file-specific image info

Add some (optional) information that the file driver can provide for
image files, namely the extent size hint.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220620162704.80987-3-hreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 54 insertions, 2 deletions

diff --git a/block/file-posix.c b/block/file-posix.c
index fa6aeea99d..d3073a7caa 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -3092,6 +3092,34 @@ raw_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     return 0;
 }
 
+static ImageInfoSpecific *raw_get_specific_info(BlockDriverState *bs,
+                                                Error **errp)
+{
+    ImageInfoSpecificFile *file_info = g_new0(ImageInfoSpecificFile, 1);
+    ImageInfoSpecific *spec_info = g_new(ImageInfoSpecific, 1);
+
+    *spec_info = (ImageInfoSpecific){
+        .type = IMAGE_INFO_SPECIFIC_KIND_FILE,
+        .u.file.data = file_info,
+    };
+
+#ifdef FS_IOC_FSGETXATTR
+    {
+        BDRVRawState *s = bs->opaque;
+        struct fsxattr attr;
+        int ret;
+
+        ret = ioctl(s->fd, FS_IOC_FSGETXATTR, &attr);
+        if (!ret && attr.fsx_extsize != 0) {
+            file_info->has_extent_size_hint = true;
+            file_info->extent_size_hint = attr.fsx_extsize;
+        }
+    }
+#endif
+
+    return spec_info;
+}
+
 static BlockStatsSpecificFile get_blockstats_specific_file(BlockDriverState *bs)
 {
     BDRVRawState *s = bs->opaque;
@@ -3325,6 +3353,7 @@ BlockDriver bdrv_file = {
     .bdrv_co_truncate                   = raw_co_truncate,
     .bdrv_co_getlength                  = raw_co_getlength,
     .bdrv_co_get_info                   = raw_co_get_info,
+    .bdrv_get_specific_info             = raw_get_specific_info,
     .bdrv_co_get_allocated_file_size    = raw_co_get_allocated_file_size,
     .bdrv_get_specific_stats = raw_get_specific_stats,
     .bdrv_check_perm = raw_check_perm,
@@ -3696,6 +3725,7 @@ static BlockDriver bdrv_host_device = {
     .bdrv_co_truncate                   = raw_co_truncate,
     .bdrv_co_getlength                  = raw_co_getlength,
     .bdrv_co_get_info                   = raw_co_get_info,
+    .bdrv_get_specific_info             = raw_get_specific_info,
     .bdrv_co_get_allocated_file_size    = raw_co_get_allocated_file_size,
     .bdrv_get_specific_stats = hdev_get_specific_stats,
     .bdrv_check_perm = raw_check_perm,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 95ac4fa634..f5d822cbd6 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -140,15 +140,28 @@
   } }
 
 ##
+# @ImageInfoSpecificFile:
+#
+# @extent-size-hint: Extent size hint (if available)
+#
+# Since: 8.0
+##
+{ 'struct': 'ImageInfoSpecificFile',
+  'data': {
+      '*extent-size-hint': 'size'
+  } }
+
+##
 # @ImageInfoSpecificKind:
 #
 # @luks: Since 2.7
 # @rbd: Since 6.1
+# @file: Since 8.0
 #
 # Since: 1.7
 ##
 { 'enum': 'ImageInfoSpecificKind',
-  'data': [ 'qcow2', 'vmdk', 'luks', 'rbd' ] }
+  'data': [ 'qcow2', 'vmdk', 'luks', 'rbd', 'file' ] }
 
 ##
 # @ImageInfoSpecificQCow2Wrapper:
@@ -186,6 +199,14 @@
   'data': { 'data': 'ImageInfoSpecificRbd' } }
 
 ##
+# @ImageInfoSpecificFileWrapper:
+#
+# Since: 8.0
+##
+{ 'struct': 'ImageInfoSpecificFileWrapper',
+  'data': { 'data': 'ImageInfoSpecificFile' } }
+
+##
 # @ImageInfoSpecific:
 #
 # A discriminated record of image format specific information structures.
@@ -199,7 +220,8 @@
       'qcow2': 'ImageInfoSpecificQCow2Wrapper',
       'vmdk': 'ImageInfoSpecificVmdkWrapper',
       'luks': 'ImageInfoSpecificLUKSWrapper',
-      'rbd': 'ImageInfoSpecificRbdWrapper'
+      'rbd': 'ImageInfoSpecificRbdWrapper',
+      'file': 'ImageInfoSpecificFileWrapper'
   } }
 
 ##