* [Qemu-devel] [PATCH 1/2] block: Fix unaligned zero write
2015-03-23 4:46 [Qemu-devel] [PATCH 0/2] block: Fix unaligned zero write Fam Zheng
@ 2015-03-23 4:46 ` Fam Zheng
2015-03-23 14:14 ` Stefan Hajnoczi
2015-03-23 4:46 ` [Qemu-devel] [PATCH 2/2] qemu-iotests: Test unaligned 4k " Fam Zheng
1 sibling, 1 reply; 6+ messages in thread
From: Fam Zheng @ 2015-03-23 4:46 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, qemu-block, qemu-stable, Stefan Hajnoczi
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(-)
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
^ permalink raw reply related [flat|nested] 6+ messages in thread* [Qemu-devel] [PATCH 2/2] qemu-iotests: Test unaligned 4k zero write
2015-03-23 4:46 [Qemu-devel] [PATCH 0/2] block: Fix unaligned zero write Fam Zheng
2015-03-23 4:46 ` [Qemu-devel] [PATCH 1/2] " Fam Zheng
@ 2015-03-23 4:46 ` Fam Zheng
1 sibling, 0 replies; 6+ messages in thread
From: Fam Zheng @ 2015-03-23 4:46 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, qemu-block, qemu-stable, Stefan Hajnoczi
Signed-off-by: Fam Zheng <famz@redhat.com>
---
tests/qemu-iotests/033 | 47 +++++++++++++++++++++++++++++-----------------
tests/qemu-iotests/033.out | 26 +++++++++++++++++++++++++
2 files changed, 56 insertions(+), 17 deletions(-)
diff --git a/tests/qemu-iotests/033 b/tests/qemu-iotests/033
index ea3351c..4008f10 100755
--- a/tests/qemu-iotests/033
+++ b/tests/qemu-iotests/033
@@ -46,26 +46,39 @@ _supported_os Linux
size=128M
_make_test_img $size
-echo
-echo "== preparing image =="
-$QEMU_IO -c "write -P 0xa 0x200 0x400" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "write -P 0xa 0x20000 0x600" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "write -z 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
+do_test()
+{
+ local align=$1
+ local iocmd=$2
+ local img=$3
+ {
+ echo "open -o driver=$IMGFMT,file.align=$align blkdebug::$img"
+ echo $iocmd
+ } | $QEMU_IO
+}
+
+for align in 512 4k; do
+ echo
+ echo "== preparing image =="
+ do_test $align "write -P 0xa 0x200 0x400" "$TEST_IMG" | _filter_qemu_io
+ do_test $align "write -P 0xa 0x20000 0x600" "$TEST_IMG" | _filter_qemu_io
+ do_test $align "write -z 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
-echo
-echo "== verifying patterns (1) =="
-$QEMU_IO -c "read -P 0xa 0x200 0x200" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0x0 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0xa 0x20400 0x200" "$TEST_IMG" | _filter_qemu_io
+ echo
+ echo "== verifying patterns (1) =="
+ do_test $align "read -P 0xa 0x200 0x200" "$TEST_IMG" | _filter_qemu_io
+ do_test $align "read -P 0x0 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
+ do_test $align "read -P 0xa 0x20400 0x200" "$TEST_IMG" | _filter_qemu_io
-echo
-echo "== rewriting zeroes =="
-$QEMU_IO -c "write -P 0xb 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "write -z 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
+ echo
+ echo "== rewriting zeroes =="
+ do_test $align "write -P 0xb 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
+ do_test $align "write -z 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
-echo
-echo "== verifying patterns (2) =="
-$QEMU_IO -c "read -P 0x0 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
+ echo
+ echo "== verifying patterns (2) =="
+ do_test $align "read -P 0x0 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
+done
# success, all done
echo "*** done"
diff --git a/tests/qemu-iotests/033.out b/tests/qemu-iotests/033.out
index 41475ee..305949f 100644
--- a/tests/qemu-iotests/033.out
+++ b/tests/qemu-iotests/033.out
@@ -26,4 +26,30 @@ wrote 65536/65536 bytes at offset 65536
== verifying patterns (2) ==
read 131072/131072 bytes at offset 1024
128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== preparing image ==
+wrote 1024/1024 bytes at offset 512
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1536/1536 bytes at offset 131072
+1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (1) ==
+read 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 132096
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== rewriting zeroes ==
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (2) ==
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
*** done
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread