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block: Add .bdrv_co_pwrite_zeroes()

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Update bdrv_co_do_write_zeroes() to be byte-based, and select
between the new byte-based bdrv_co_pwrite_zeroes() or the old
bdrv_co_write_zeroes().  The next patches will convert drivers,
then remove the old interface.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2016-06-01 15:10:03 -06:00 committed by Kevin Wolf
parent cf081fca4e
commit d05aa8bb4a
2 changed files with 46 additions and 36 deletions
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78
block/io.c
View file

@ -42,8 +42,8 @@ static BlockAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
void *opaque,
bool is_write);
static void coroutine_fn bdrv_co_do_rw(void *opaque);
static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags);
static void bdrv_parent_drained_begin(BlockDriverState *bs)
{
@ -893,10 +893,12 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
goto err;
}
if (drv->bdrv_co_write_zeroes &&
if ((drv->bdrv_co_write_zeroes || drv->bdrv_co_pwrite_zeroes) &&
buffer_is_zero(bounce_buffer, iov.iov_len)) {
ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num,
cluster_nb_sectors, 0);
ret = bdrv_co_do_pwrite_zeroes(bs,
cluster_sector_num * BDRV_SECTOR_SIZE,
cluster_nb_sectors * BDRV_SECTOR_SIZE,
0);
} else {
/* This does not change the data on the disk, it is not necessary
* to flush even in cache=writethrough mode.
@ -1110,8 +1112,8 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
#define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768
static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags)
{
BlockDriver *drv = bs->drv;
QEMUIOVector qiov;
@ -1122,20 +1124,16 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
int tail = 0;
int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_pwrite_zeroes, INT_MAX);
int write_zeroes_sector_align =
bs->bl.pwrite_zeroes_alignment >> BDRV_SECTOR_BITS;
int alignment = MAX(bs->bl.pwrite_zeroes_alignment ?: 1,
bs->request_alignment);
max_write_zeroes >>= BDRV_SECTOR_BITS;
if (write_zeroes_sector_align) {
assert(is_power_of_2(bs->bl.pwrite_zeroes_alignment));
head = sector_num & (write_zeroes_sector_align - 1);
tail = (sector_num + nb_sectors) & (write_zeroes_sector_align - 1);
max_write_zeroes &= ~(write_zeroes_sector_align - 1);
}
assert(is_power_of_2(alignment));
head = offset & (alignment - 1);
tail = (offset + count) & (alignment - 1);
max_write_zeroes &= ~(alignment - 1);
assert(nb_sectors <= BDRV_REQUEST_MAX_SECTORS);
while (nb_sectors > 0 && !ret) {
int num = nb_sectors;
while (count > 0 && !ret) {
int num = count;
/* Align request. Block drivers can expect the "bulk" of the request
* to be aligned, and that unaligned requests do not cross cluster
@ -1143,9 +1141,9 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
*/
if (head) {
/* Make a small request up to the first aligned sector. */
num = MIN(nb_sectors, write_zeroes_sector_align - head);
num = MIN(count, alignment - head);
head = 0;
} else if (tail && num > write_zeroes_sector_align) {
} else if (tail && num > alignment) {
/* Shorten the request to the last aligned sector. */
num -= tail;
}
@ -1157,8 +1155,18 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
ret = -ENOTSUP;
/* First try the efficient write zeroes operation */
if (drv->bdrv_co_write_zeroes) {
ret = drv->bdrv_co_write_zeroes(bs, sector_num, num,
if (drv->bdrv_co_pwrite_zeroes) {
ret = drv->bdrv_co_pwrite_zeroes(bs, offset, num,
flags & bs->supported_zero_flags);
if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) &&
!(bs->supported_zero_flags & BDRV_REQ_FUA)) {
need_flush = true;
}
} else if (drv->bdrv_co_write_zeroes) {
assert(offset % BDRV_SECTOR_SIZE == 0);
assert(count % BDRV_SECTOR_SIZE == 0);
ret = drv->bdrv_co_write_zeroes(bs, offset >> BDRV_SECTOR_BITS,
num >> BDRV_SECTOR_BITS,
flags & bs->supported_zero_flags);
if (ret != -ENOTSUP && (flags & BDRV_REQ_FUA) &&
!(bs->supported_zero_flags & BDRV_REQ_FUA)) {
@ -1181,33 +1189,31 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
write_flags &= ~BDRV_REQ_FUA;
need_flush = true;
}
num = MIN(num, max_xfer_len);
iov.iov_len = num * BDRV_SECTOR_SIZE;
num = MIN(num, max_xfer_len << BDRV_SECTOR_BITS);
iov.iov_len = num;
if (iov.iov_base == NULL) {
iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
iov.iov_base = qemu_try_blockalign(bs, num);
if (iov.iov_base == NULL) {
ret = -ENOMEM;
goto fail;
}
memset(iov.iov_base, 0, num * BDRV_SECTOR_SIZE);
memset(iov.iov_base, 0, num);
}
qemu_iovec_init_external(&qiov, &iov, 1);
ret = bdrv_driver_pwritev(bs, sector_num * BDRV_SECTOR_SIZE,
num * BDRV_SECTOR_SIZE, &qiov,
write_flags);
ret = bdrv_driver_pwritev(bs, offset, num, &qiov, write_flags);
/* Keep bounce buffer around if it is big enough for all
* all future requests.
*/
if (num < max_xfer_len) {
if (num < max_xfer_len << BDRV_SECTOR_BITS) {
qemu_vfree(iov.iov_base);
iov.iov_base = NULL;
}
}
sector_num += num;
nb_sectors -= num;
offset += num;
count -= num;
}
fail:
@ -1245,7 +1251,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
!(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_write_zeroes &&
!(flags & BDRV_REQ_ZERO_WRITE) &&
(drv->bdrv_co_pwrite_zeroes || drv->bdrv_co_write_zeroes) &&
qemu_iovec_is_zero(qiov)) {
flags |= BDRV_REQ_ZERO_WRITE;
if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
@ -1257,7 +1264,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
/* Do nothing, write notifier decided to fail this request */
} else if (flags & BDRV_REQ_ZERO_WRITE) {
bdrv_debug_event(bs, BLKDBG_PWRITEV_ZERO);
ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors, flags);
ret = bdrv_co_do_pwrite_zeroes(bs, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, flags);
} else {
bdrv_debug_event(bs, BLKDBG_PWRITEV);
ret = bdrv_driver_pwritev(bs, offset, bytes, qiov, flags);

4
include/block/block_int.h
View file

@ -165,6 +165,8 @@ struct BlockDriver {
*/
int coroutine_fn (*bdrv_co_write_zeroes)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
int coroutine_fn (*bdrv_co_pwrite_zeroes)(BlockDriverState *bs,
int64_t offset, int count, BdrvRequestFlags flags);
int coroutine_fn (*bdrv_co_discard)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors);
int64_t coroutine_fn (*bdrv_co_get_block_status)(BlockDriverState *bs,
@ -456,7 +458,7 @@ struct BlockDriverState {
unsigned int request_alignment;
/* Flags honored during pwrite (so far: BDRV_REQ_FUA) */
unsigned int supported_write_flags;
/* Flags honored during write_zeroes (so far: BDRV_REQ_FUA,
/* Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA,
* BDRV_REQ_MAY_UNMAP) */
unsigned int supported_zero_flags;