From 081e465026769a24b86ba2e6a77709cfea33f16a Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Wed, 12 Jun 2019 18:14:13 +0200 Subject: [PATCH] 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 --- block.c | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index ac4ab07f07..63c7d9b1a7 100644 --- a/block.c +++ b/block.c @@ -5005,6 +5005,31 @@ exit: return ret; } +/** + * 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; } /*