diff options
Diffstat (limited to 'block/io.c')
| -rw-r--r-- | block/io.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/block/io.c b/block/io.c index 1eb2b2bddc..7e4cb74cf4 100644 --- a/block/io.c +++ b/block/io.c @@ -1565,10 +1565,12 @@ static bool bdrv_init_padding(BlockDriverState *bs, pad->tail = align - pad->tail; } - if ((!pad->head && !pad->tail) || !bytes) { + if (!pad->head && !pad->tail) { return false; } + assert(bytes); /* Nothing good in aligning zero-length requests */ + sum = pad->head + bytes + pad->tail; pad->buf_len = (sum > align && pad->head && pad->tail) ? 2 * align : align; pad->buf = qemu_blockalign(bs, pad->buf_len); @@ -1706,6 +1708,18 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child, return ret; } + if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) { + /* + * Aligning zero request is nonsense. Even if driver has special meaning + * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass + * it to driver due to request_alignment. + * + * Still, no reason to return an error if someone do unaligned + * zero-length read occasionally. + */ + return 0; + } + bdrv_inc_in_flight(bs); /* Don't do copy-on-read if we read data before write operation */ @@ -2116,6 +2130,18 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child, return -ENOTSUP; } + if (bytes == 0 && !QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)) { + /* + * Aligning zero request is nonsense. Even if driver has special meaning + * of zero-length (like qcow2_co_pwritev_compressed_part), we can't pass + * it to driver due to request_alignment. + * + * Still, no reason to return an error if someone do unaligned + * zero-length write occasionally. + */ + return 0; + } + bdrv_inc_in_flight(bs); /* * Align write if necessary by performing a read-modify-write cycle. |