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authorFam Zheng <famz@redhat.com>2015-03-24 09:23:49 +0800
committerStefan Hajnoczi <stefanha@redhat.com>2015-03-27 10:01:12 +0000
commitfc3959e4669a1c2149b91ccb05101cfc7ae1fc05 (patch)
treeb3e2be4c49d43cd621a579de7865c3687b7b59e9 /block.c
parent2115f2a1d8c77c2a735add1ed02ae0c1feae0d9a (diff)
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block: Fix unaligned zero write
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> Message-id: 1427160230-4489-2-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c45
1 files changed, 39 insertions, 6 deletions
diff --git a/block.c b/block.c
index 0fe97de..f2f8ae7 100644
--- a/block.c
+++ b/block.c
@@ -3118,6 +3118,19 @@ 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
*/
@@ -3128,8 +3141,7 @@ 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;
@@ -3371,8 +3383,7 @@ 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;
@@ -3471,6 +3482,10 @@ 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);
@@ -3511,14 +3526,32 @@ 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);
- 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;
}
/**