diff options
| author | Hanna Reitz <hreitz@redhat.com> | 2022-01-18 17:59:59 +0100 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2022-01-28 16:52:40 -0600 |
| commit | 113b727ce788335cf76f65355d670c9bc130fd75 (patch) | |
| tree | f88a392bce62431f6bbe9415895132cc1a0783d9 /block/io.c | |
| parent | 3a8fa0edd18f76e222d983a31e486e76a51348a7 (diff) | |
block/io: Update BSC only if want_zero is true
We update the block-status cache whenever we get new information from a
bdrv_co_block_status() call to the block driver. However, if we have
passed want_zero=false to that call, it may flag areas containing zeroes
as data, and so we would update the block-status cache with wrong
information.
Therefore, we should not update the cache with want_zero=false.
Reported-by: Nir Soffer <nsoffer@redhat.com>
Fixes: 0bc329fbb00 ("block: block-status cache for data regions")
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220118170000.49423-2-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'block/io.c')
| -rw-r--r-- | block/io.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/block/io.c b/block/io.c index bb0a254def..4e4cb556c5 100644 --- a/block/io.c +++ b/block/io.c @@ -2497,8 +2497,12 @@ static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs, * non-protocol nodes, and then it is never used. However, filling * the cache requires an RCU update, so double check here to avoid * such an update if possible. + * + * Check want_zero, because we only want to update the cache when we + * have accurate information about what is zero and what is data. */ - if (ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) && + if (want_zero && + ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) && QLIST_EMPTY(&bs->children)) { /* |