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block: Convert bdrv_get_block_status_above() to bytes

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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 name of the function from bdrv_get_block_status_above()
to bdrv_block_status_above() ensures that the compiler enforces that
all callers are updated.  Likewise, since it a byte interface allows
an offset mapping that might not be sector aligned, split the mapping
out of the return value and into a pass-by-reference parameter.  For
now, the io.c layer still assert()s that all uses are sector-aligned,
but that can be relaxed when a later patch implements byte-based
block status in the drivers.

For the most part this patch is just the addition of scaling at the
callers followed by inverse scaling at bdrv_block_status(), plus
updates for the new split return interface.  But some code,
particularly bdrv_block_status(), gets a lot simpler because it no
longer has to mess with sectors.  Likewise, mirror code no longer
computes s->granularity >> BDRV_SECTOR_BITS, and can therefore drop
an assertion about alignment because the loop no longer depends on
alignment (never mind that we don't really have a driver that
reports sub-sector alignments, so it's not really possible to test
the effect of sub-sector mirroring).  Fix a neighboring assertion to
use is_power_of_2 while there.

For ease of review, bdrv_get_block_status() 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 2017-10-11 22:47:08 -05:00 • committed by Kevin Wolf
parent 5b648c67e3
commit 3182664220
5 changed files with 57 additions and 103 deletions
Download patch file Download diff file Expand all files Collapse all files

49
qemu-img.c
View file

@ -1226,7 +1226,7 @@ static int img_compare(int argc, char **argv)
BlockDriverState *bs1, *bs2;
int64_t total_sectors1, total_sectors2;
uint8_t *buf1 = NULL, *buf2 = NULL;
int pnum1, pnum2;
int64_t pnum1, pnum2;
int allocated1, allocated2;
int ret = 0; /* return value - 0 Ident, 1 Different, >1 Error */
bool progress = false, quiet = false, strict = false;
@ -1374,15 +1374,17 @@ static int img_compare(int argc, char **argv)
}
for (;;) {
int64_t status1, status2;
int status1, status2;
nb_sectors = sectors_to_process(total_sectors, sector_num);
if (nb_sectors <= 0) {
break;
}
status1 = bdrv_get_block_status_above(bs1, NULL, sector_num,
total_sectors1 - sector_num,
&pnum1, NULL);
status1 = bdrv_block_status_above(bs1, NULL,
sector_num * BDRV_SECTOR_SIZE,
(total_sectors1 - sector_num) *
BDRV_SECTOR_SIZE,
&pnum1, NULL, NULL);
if (status1 < 0) {
ret = 3;
error_report("Sector allocation test failed for %s", filename1);
@ -1390,25 +1392,29 @@ static int img_compare(int argc, char **argv)
}
allocated1 = status1 & BDRV_BLOCK_ALLOCATED;
status2 = bdrv_get_block_status_above(bs2, NULL, sector_num,
total_sectors2 - sector_num,
&pnum2, NULL);
status2 = bdrv_block_status_above(bs2, NULL,
sector_num * BDRV_SECTOR_SIZE,
(total_sectors2 - sector_num) *
BDRV_SECTOR_SIZE,
&pnum2, NULL, NULL);
if (status2 < 0) {
ret = 3;
error_report("Sector allocation test failed for %s", filename2);
goto out;
}
allocated2 = status2 & BDRV_BLOCK_ALLOCATED;
/* TODO: Relax this once comparison is byte-based, and we no longer
* have to worry about sector alignment */
assert(QEMU_IS_ALIGNED(pnum1 | pnum2, BDRV_SECTOR_SIZE));
if (pnum1) {
nb_sectors = MIN(nb_sectors, pnum1);
nb_sectors = MIN(nb_sectors, pnum1 >> BDRV_SECTOR_BITS);
}
if (pnum2) {
nb_sectors = MIN(nb_sectors, pnum2);
nb_sectors = MIN(nb_sectors, pnum2 >> BDRV_SECTOR_BITS);
}
if (strict) {
if ((status1 & ~BDRV_BLOCK_OFFSET_MASK) !=
(status2 & ~BDRV_BLOCK_OFFSET_MASK)) {
if (status1 != status2) {
ret = 1;
qprintf(quiet, "Strict mode: Offset %" PRId64
" block status mismatch!\n",
@ -1417,7 +1423,7 @@ static int img_compare(int argc, char **argv)
}
}
if ((status1 & BDRV_BLOCK_ZERO) && (status2 & BDRV_BLOCK_ZERO)) {
nb_sectors = MIN(pnum1, pnum2);
nb_sectors = DIV_ROUND_UP(MIN(pnum1, pnum2), BDRV_SECTOR_SIZE);
} else if (allocated1 == allocated2) {
if (allocated1) {
ret = blk_pread(blk1, sector_num << BDRV_SECTOR_BITS, buf1,
@ -1589,8 +1595,8 @@ static void convert_select_part(ImgConvertState *s, int64_t sector_num,
static int convert_iteration_sectors(ImgConvertState *s, int64_t sector_num)
{
int64_t ret, src_cur_offset;
int n, src_cur;
int64_t src_cur_offset;
int ret, n, src_cur;
convert_select_part(s, sector_num, &src_cur, &src_cur_offset);
@ -1598,23 +1604,24 @@ static int convert_iteration_sectors(ImgConvertState *s, int64_t sector_num)
n = MIN(s->total_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
if (s->sector_next_status <= sector_num) {
int64_t count = n * BDRV_SECTOR_SIZE;
if (s->target_has_backing) {
int64_t count = n * BDRV_SECTOR_SIZE;
ret = bdrv_block_status(blk_bs(s->src[src_cur]),
(sector_num - src_cur_offset) *
BDRV_SECTOR_SIZE,
count, &count, NULL, NULL);
assert(ret < 0 || QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE));
n = count >> BDRV_SECTOR_BITS;
} else {
ret = bdrv_get_block_status_above(blk_bs(s->src[src_cur]), NULL,
sector_num - src_cur_offset,
n, &n, NULL);
ret = bdrv_block_status_above(blk_bs(s->src[src_cur]), NULL,
(sector_num - src_cur_offset) *
BDRV_SECTOR_SIZE,
count, &count, NULL, NULL);
}
if (ret < 0) {
return ret;
}
n = DIV_ROUND_UP(count, BDRV_SECTOR_SIZE);
if (ret & BDRV_BLOCK_ZERO) {
s->status = BLK_ZERO;