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authorMax Reitz <mreitz@redhat.com>2019-06-12 18:14:13 +0200
committerKevin Wolf <kwolf@redhat.com>2020-09-07 12:31:31 +0200
commit081e465026769a24b86ba2e6a77709cfea33f16a (patch)
tree7fcf59220af674ee450618289de6cb8e609061d9
parentf706a92f249b573c624fa5a8067fa1c6636a6ae0 (diff)
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block: Improve get_allocated_file_size's default
There are two practical problems with bdrv_get_allocated_file_size()'s default right now: (1) For drivers with children, we should generally sum all their sizes instead of just passing the request through to bs->file. The latter is good for filters, but not so much for format drivers. (2) Filters need not have bs->file, so we should actually go to the filtered child instead of hard-coding bs->file. Fix this by splitting the default implementation into three branches: (1) For filter drivers: Return the size of the filtered child (2) For protocol drivers: Return -ENOTSUP, because the default implementation cannot make a guess (3) For other drivers: Sum all data-bearing children's sizes Signed-off-by: Max Reitz <mreitz@redhat.com>
-rw-r--r--block.c42
1 files changed, 39 insertions, 3 deletions
diff --git a/block.c b/block.c
index ac4ab07..63c7d9b 100644
--- a/block.c
+++ b/block.c
@@ -5006,6 +5006,31 @@ exit:
}
/**
+ * Implementation of BlockDriver.bdrv_get_allocated_file_size() that
+ * sums the size of all data-bearing children. (This excludes backing
+ * children.)
+ */
+static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs)
+{
+ BdrvChild *child;
+ int64_t child_size, sum = 0;
+
+ QLIST_FOREACH(child, &bs->children, next) {
+ if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
+ BDRV_CHILD_FILTERED))
+ {
+ child_size = bdrv_get_allocated_file_size(child->bs);
+ if (child_size < 0) {
+ return child_size;
+ }
+ sum += child_size;
+ }
+ }
+
+ return sum;
+}
+
+/**
* Length of a allocated file in bytes. Sparse files are counted by actual
* allocated space. Return < 0 if error or unknown.
*/
@@ -5018,10 +5043,21 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
if (drv->bdrv_get_allocated_file_size) {
return drv->bdrv_get_allocated_file_size(bs);
}
- if (bs->file) {
- return bdrv_get_allocated_file_size(bs->file->bs);
+
+ if (drv->bdrv_file_open) {
+ /*
+ * Protocol drivers default to -ENOTSUP (most of their data is
+ * not stored in any of their children (if they even have any),
+ * so there is no generic way to figure it out).
+ */
+ return -ENOTSUP;
+ } else if (drv->is_filter) {
+ /* Filter drivers default to the size of their filtered child */
+ return bdrv_get_allocated_file_size(bdrv_filter_bs(bs));
+ } else {
+ /* Other drivers default to summing their children's sizes */
+ return bdrv_sum_allocated_file_size(bs);
}
- return -ENOTSUP;
}
/*