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block: Fix unaligned zero write

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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>
This commit is contained in:
Fam Zheng 2015-03-24 09:23:49 +08:00 committed by Stefan Hajnoczi
parent 2115f2a1d8
commit fc3959e466
1 changed files with 39 additions and 6 deletions
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45
block.c
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@ -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;
return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
BDRV_REQ_ZERO_WRITE | flags);
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);
ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, &local_qiov,
BDRV_REQ_ZERO_WRITE | flags);
qemu_vfree(buf);
}
return ret;
}
/**