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block: Make bdrv_is_allocated_above() byte-based

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We are gradually moving away from sector-based interfaces, towards
byte-based.  In the common case, allocation is unlikely to ever use
values that are not naturally sector-aligned, but it is possible
that byte-based values will let us be more precise about allocation
at the end of an unaligned file that can do byte-based access.

Changing the signature of the function to use int64_t *pnum ensures
that the compiler enforces that all callers are updated.  For now,
the io.c layer still assert()s that all callers are sector-aligned,
but that can be relaxed when a later patch implements byte-based
block status.  Therefore, for the most part this patch is just the
addition of scaling at the callers followed by inverse scaling at
bdrv_is_allocated().  But some code, particularly stream_run(),
gets a lot simpler because it no longer has to mess with sectors.
Leave comments where we can further simplify by switching to
byte-based iterations, once later patches eliminate the need for
sector-aligned operations.

For ease of review, bdrv_is_allocated() was tackled separately.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-07-07 07:44:59 -05:00 • committed by Kevin Wolf
parent c00716beb3
commit 51b0a48888
7 changed files with 65 additions and 56 deletions
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17
block/replication.c
View file

@ -264,7 +264,8 @@ static coroutine_fn int replication_co_writev(BlockDriverState *bs,
BdrvChild *top = bs->file;
BdrvChild *base = s->secondary_disk;
BdrvChild *target;
int ret, n;
int ret;
int64_t n;
ret = replication_get_io_status(s);
if (ret < 0) {
@ -283,14 +284,20 @@ static coroutine_fn int replication_co_writev(BlockDriverState *bs,
*/
qemu_iovec_init(&hd_qiov, qiov->niov);
while (remaining_sectors > 0) {
ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
remaining_sectors, &n);
int64_t count;
ret = bdrv_is_allocated_above(top->bs, base->bs,
sector_num * BDRV_SECTOR_SIZE,
remaining_sectors * BDRV_SECTOR_SIZE,
&count);
if (ret < 0) {
goto out1;
}
assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE));
n = count >> BDRV_SECTOR_BITS;
qemu_iovec_reset(&hd_qiov);
qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count);
target = ret ? top : base;
ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
@ -300,7 +307,7 @@ static coroutine_fn int replication_co_writev(BlockDriverState *bs,
remaining_sectors -= n;
sector_num += n;
bytes_done += n * BDRV_SECTOR_SIZE;
bytes_done += count;
}
out1: