Message ID | 1427085970-23823-2-git-send-email-famz@redhat.com |
---|---|
State | New |
Headers | show |
On Mon, Mar 23, 2015 at 12:46:09PM +0800, Fam Zheng wrote: > @@ -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; > - } Why is it okay to drop this when the request is aligned? > + 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 {
Am 23.03.2015 um 15:14 schrieb Stefan Hajnoczi: > On Mon, Mar 23, 2015 at 12:46:09PM +0800, Fam Zheng wrote: >> @@ -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; >> - } > Why is it okay to drop this when the request is aligned? I also think it is not. This is the only point in the code that clears the MAY_UNMAP flag when we do not open with discard=on Peter
On Mon, 03/23 14:14, Stefan Hajnoczi wrote: > On Mon, Mar 23, 2015 at 12:46:09PM +0800, Fam Zheng wrote: > > @@ -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; > > - } > > Why is it okay to drop this when the request is aligned? It's not. I will restore it. > > > + 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 {
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; } /**
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 <famz@redhat.com> --- block.c | 51 ++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 42 insertions(+), 9 deletions(-)