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raw_bsd: Convert to byte-based interface

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Since the raw format driver is just passing things through, we can
do byte-based read and write if the underlying protocol does
likewise.

There's one tricky part - if we probed the image format, we document
that we restrict operations on the initial sector.  It's easiest to
keep this guarantee by enforcing read-modify-write on sub-sector
operations (yes, this partially reverts commit ad82be2f).

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 1468624988-423-20-git-send-email-eblake@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Eric Blake 2016-07-15 17:23:08 -06:00 committed by Stefan Hajnoczi
parent 70c4fb2648
commit decaeed773
1 changed files with 26 additions and 19 deletions
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45
block/raw_bsd.c
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@ -50,33 +50,30 @@ static int raw_reopen_prepare(BDRVReopenState *reopen_state,
return 0;
}
static int coroutine_fn raw_co_readv(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
return bdrv_co_readv(bs->file, sector_num, nb_sectors, qiov);
return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn
raw_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
QEMUIOVector *qiov, int flags)
static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
void *buf = NULL;
BlockDriver *drv;
QEMUIOVector local_qiov;
int ret;
if (bs->probed && sector_num == 0) {
/* As long as these conditions are true, we can't get partial writes to
* the probe buffer and can just directly check the request. */
if (bs->probed && offset < BLOCK_PROBE_BUF_SIZE && bytes) {
/* Handling partial writes would be a pain - so we just
* require that guests have 512-byte request alignment if
* probing occurred */
QEMU_BUILD_BUG_ON(BLOCK_PROBE_BUF_SIZE != 512);
QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != 512);
if (nb_sectors == 0) {
/* qemu_iovec_to_buf() would fail, but we want to return success
* instead of -EINVAL in this case. */
return 0;
}
assert(offset == 0 && bytes >= BLOCK_PROBE_BUF_SIZE);
buf = qemu_try_blockalign(bs->file->bs, 512);
if (!buf) {
@ -105,8 +102,7 @@ raw_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
}
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
ret = bdrv_co_pwritev(bs->file, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE, qiov, flags);
ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
fail:
if (qiov == &local_qiov) {
@ -150,6 +146,16 @@ static int raw_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
return bdrv_get_info(bs->file->bs, bdi);
}
static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
{
if (bs->probed) {
/* To make it easier to protect the first sector, any probed
* image is restricted to read-modify-write on sub-sector
* operations. */
bs->bl.request_alignment = BDRV_SECTOR_SIZE;
}
}
static int raw_truncate(BlockDriverState *bs, int64_t offset)
{
return bdrv_truncate(bs->file->bs, offset);
@ -240,8 +246,8 @@ BlockDriver bdrv_raw = {
.bdrv_open = &raw_open,
.bdrv_close = &raw_close,
.bdrv_create = &raw_create,
.bdrv_co_readv = &raw_co_readv,
.bdrv_co_writev_flags = &raw_co_writev_flags,
.bdrv_co_preadv = &raw_co_preadv,
.bdrv_co_pwritev = &raw_co_pwritev,
.bdrv_co_pwrite_zeroes = &raw_co_pwrite_zeroes,
.bdrv_co_pdiscard = &raw_co_pdiscard,
.bdrv_co_get_block_status = &raw_co_get_block_status,
@ -249,6 +255,7 @@ BlockDriver bdrv_raw = {
.bdrv_getlength = &raw_getlength,
.has_variable_length = true,
.bdrv_get_info = &raw_get_info,
.bdrv_refresh_limits = &raw_refresh_limits,
.bdrv_probe_blocksizes = &raw_probe_blocksizes,
.bdrv_probe_geometry = &raw_probe_geometry,
.bdrv_media_changed = &raw_media_changed,