[Qemu-devel] [PATCH v2 5/9] block: Fix handling of image enlarging write

[Fam Zheng <famz@redhat.com>]

Two problems exist when a write request that enlarges the image (i.e.
write beyond EOF) finishes:

1) parent is not notified about size change;
2) dirty bitmap is not resized although we try to set the dirty bits;

Fix them just like how bdrv_co_truncate works.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/io.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/block/io.c b/block/io.c
index 03d9eb0a65..f06978dda0 100644
--- a/block/io.c
+++ b/block/io.c
@@ -40,6 +40,7 @@
 
 static AioWait drain_all_aio_wait;
 
+static void bdrv_parent_cb_resize(BlockDriverState *bs);
 static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
     int64_t offset, int bytes, BdrvRequestFlags flags);
 
@@ -1571,13 +1572,17 @@ bdrv_co_write_req_finish(BdrvChild *child, BdrvTrackedRequest *req, int ret)
     BlockDriverState *bs = child->bs;
 
     atomic_inc(&bs->write_gen);
-    bdrv_set_dirty(bs, req->offset, req->bytes);
 
     stat64_max(&bs->wr_highest_offset, req->offset + req->bytes);
 
-    if (ret == 0) {
-        bs->total_sectors = MAX(bs->total_sectors, end_sector);
+    if (req->type != BDRV_TRACKED_DISCARD &&
+        ret == 0 &&
+        end_sector > bs->total_sectors) {
+        bs->total_sectors = end_sector;
+        bdrv_parent_cb_resize(bs);
+        bdrv_dirty_bitmap_truncate(bs, end_sector << BDRV_SECTOR_BITS);
     }
+    bdrv_set_dirty(bs, req->offset, req->bytes);
 }
 
 /*
-- 
2.17.1