[Qemu-devel] [PULL 08/25] raw-posix: Fix .bdrv_co_get_block_status() for unaligned image size

[Kevin Wolf <kwolf@redhat.com>]

Image files with an unaligned image size have a final hole that starts
at EOF, i.e. in the middle of a sector. Currently, *pnum == 0 is
returned when checking the status of this sector. In qemu-img, this
triggers an assertion failure.

In order to fix this, one type for the sector that contains EOF must be
found. Treating a hole as data is safe, so this patch rounds the
calculated number of data sectors up, so that a partial sector at EOF is
treated as a full data sector.

This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1229394

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Cole Robinson <crobinso@redhat.com>
---
 block/raw-posix.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 2990e95..44ade8c 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1848,8 +1848,9 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
         *pnum = nb_sectors;
         ret = BDRV_BLOCK_DATA;
     } else if (data == start) {
-        /* On a data extent, compute sectors to the end of the extent.  */
-        *pnum = MIN(nb_sectors, (hole - start) / BDRV_SECTOR_SIZE);
+        /* On a data extent, compute sectors to the end of the extent,
+         * possibly including a partial sector at EOF. */
+        *pnum = MIN(nb_sectors, DIV_ROUND_UP(hole - start, BDRV_SECTOR_SIZE));
         ret = BDRV_BLOCK_DATA;
     } else {
         /* On a hole, compute sectors to the beginning of the next extent.  */
-- 
1.8.3.1