diff options
| -rw-r--r-- | block/io.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/block/io.c b/block/io.c index e579eda504..959e1401df 100644 --- a/block/io.c +++ b/block/io.c @@ -1179,6 +1179,8 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX); int alignment = MAX(bs->bl.pwrite_zeroes_alignment, bs->bl.request_alignment); + int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, + MAX_WRITE_ZEROES_BOUNCE_BUFFER); assert(alignment % bs->bl.request_alignment == 0); head = offset % alignment; @@ -1194,9 +1196,12 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, * boundaries. */ if (head) { - /* Make a small request up to the first aligned sector. */ - num = MIN(count, alignment - head); - head = 0; + /* Make a small request up to the first aligned sector. For + * convenience, limit this request to max_transfer even if + * we don't need to fall back to writes. */ + num = MIN(MIN(count, max_transfer), alignment - head); + head = (head + num) % alignment; + assert(num < max_write_zeroes); } else if (tail && num > alignment) { /* Shorten the request to the last aligned sector. */ num -= tail; @@ -1222,8 +1227,6 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, if (ret == -ENOTSUP) { /* Fall back to bounce buffer if write zeroes is unsupported */ - int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, - MAX_WRITE_ZEROES_BOUNCE_BUFFER); BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE; if ((flags & BDRV_REQ_FUA) && |