[Qemu-devel] [PULL 22/42] block: keep bs->total_sectors up to date even for growable block devices

[Stefan Hajnoczi]

From: Paolo Bonzini <address@hidden>

If a BlockDriverState is growable, after every write we need to
check if bs->total_sectors might have changed.  With this change,
bdrv_getlength does not need anymore a system call.

Signed-off-by: Paolo Bonzini <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 block.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 905bf34..d9a3a7f 100644
--- a/block.c
+++ b/block.c
@@ -2739,6 +2739,9 @@ static int coroutine_fn 
bdrv_co_do_writev(BlockDriverState *bs,
     if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
         bs->wr_highest_sector = sector_num + nb_sectors - 1;
     }
+    if (bs->growable && ret >= 0) {
+        bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
+    }
 
     tracked_request_end(&req);
 
@@ -2813,7 +2816,7 @@ int64_t bdrv_getlength(BlockDriverState *bs)
     if (!drv)
         return -ENOMEDIUM;
 
-    if (bs->growable || bdrv_dev_has_removable_media(bs)) {
+    if (bdrv_dev_has_removable_media(bs)) {
         if (drv->bdrv_getlength) {
             return drv->bdrv_getlength(bs);
         }
-- 
1.8.3.1