If the zero write is not aligned, bdrv_co_do_pwritev will segfault
because of accessing to the NULL qiov passed in by bdrv_co_write_zeroes.
Fix this by allocating a local qiov in bdrv_co_do_pwritev if the request
is not aligned. (In this case the padding iovs are necessary anyway, so
it doesn't hurt.)
Also add a check at the end of bdrv_co_do_pwritev to clear the zero flag
if padding is involved.
Signed-off-by: Fam Zheng <f...@redhat.com>
---
block.c | 51 ++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 42 insertions(+), 9 deletions(-)
diff --git a/block.c b/block.c
index 210fd5f..469b509 100644
--- a/block.c
+++ b/block.c
@@ -3086,6 +3086,19 @@ out:
return ret;
}
+static inline uint64_t bdrv_get_align(BlockDriverState *bs)
+{
+ /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
+ return MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
+}
+
+static inline bool bdrv_req_is_aligned(BlockDriverState *bs,
+ int64_t offset, size_t bytes)
+{
+ int64_t align = bdrv_get_align(bs);
+ return !(offset & (align - 1) || (bytes & (align - 1)));
+}
+
/*
* Handle a read request in coroutine context
*/
@@ -3096,8 +3109,7 @@ static int coroutine_fn
bdrv_co_do_preadv(BlockDriverState *bs,
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
- /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
- uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
+ uint64_t align = bdrv_get_align(bs);
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
@@ -3337,8 +3349,7 @@ static int coroutine_fn
bdrv_co_do_pwritev(BlockDriverState *bs,
BdrvRequestFlags flags)
{
BdrvTrackedRequest req;
- /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
- uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
+ uint64_t align = bdrv_get_align(bs);
uint8_t *head_buf = NULL;
uint8_t *tail_buf = NULL;
QEMUIOVector local_qiov;
@@ -3435,6 +3446,10 @@ static int coroutine_fn
bdrv_co_do_pwritev(BlockDriverState *bs,
bytes = ROUND_UP(bytes, align);
}
+ if (use_local_qiov) {
+ /* Local buffer may have non-zero data. */
+ flags &= ~BDRV_REQ_ZERO_WRITE;
+ }
ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
use_local_qiov ? &local_qiov : qiov,
flags);
@@ -3475,14 +3490,32 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState
*bs,
int64_t sector_num, int nb_sectors,
BdrvRequestFlags flags)
{
+ int ret;
+
trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
- if (!(bs->open_flags & BDRV_O_UNMAP)) {
- flags &= ~BDRV_REQ_MAY_UNMAP;
- }
+ if (bdrv_req_is_aligned(bs, sector_num << BDRV_SECTOR_BITS,
+ nb_sectors << BDRV_SECTOR_BITS)) {
+ ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
+ BDRV_REQ_ZERO_WRITE | flags);
+ } else {
+ uint8_t *buf;
+ QEMUIOVector local_qiov;
+ size_t bytes = nb_sectors << BDRV_SECTOR_BITS;
+
+ buf = qemu_memalign(bdrv_opt_mem_align(bs), bytes);
+ memset(buf, 0, bytes);
+ qemu_iovec_init(&local_qiov, 1);
+ qemu_iovec_add(&local_qiov, buf, bytes);
+ if (!(bs->open_flags & BDRV_O_UNMAP)) {
+ flags &= ~BDRV_REQ_MAY_UNMAP;
+ }
- return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
- BDRV_REQ_ZERO_WRITE | flags);
+ ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, &local_qiov,
+ BDRV_REQ_ZERO_WRITE | flags);
+ qemu_vfree(buf);
+ }
+ return ret;
}
/**
--
2.1.0
