| Message ID | 20170913160333.23622-2-eblake@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | make bdrv_get_block_status byte-based | expand |
On 09/13/2017 12:03 PM, Eric Blake wrote: > Not all callers care about which BDS owns the mapping for a given > range of the file. This patch merely simplifies the callers by > consolidating the logic in the common call point, while guaranteeing > a non-NULL file to all the driver callbacks, for no semantic change. > The only caller that does not care about pnum is bdrv_is_allocated, > as invoked by vvfat; we can likewise add assertions that the rest > of the stack does not have to worry about a NULL pnum. > > Furthermore, this will also set the stage for a future cleanup: when > a caller does not care about which BDS owns an offset, it would be > nice to allow the driver to optimize things to not have to return > BDRV_BLOCK_OFFSET_VALID in the first place. In the case of fragmented > allocation (for example, it's fairly easy to create a qcow2 image > where consecutive guest addresses are not at consecutive host > addresses), the current contract requires bdrv_get_block_status() > to clamp *pnum to the limit where host addresses are no longer > consecutive, but allowing a NULL file means that *pnum could be > set to the full length of known-allocated data. > > Signed-off-by: Eric Blake <eblake@redhat.com> > > --- > v4: only context changes > v3: rebase to recent changes (qcow2_measure), dropped R-b > v2: use local variable and final transfer, rather than assignment > of parameter to local > [previously in different series]: > v2: new patch, https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg05645.html > --- > include/block/block_int.h | 10 ++++++---- > block/io.c | 44 ++++++++++++++++++++++++++++---------------- > block/mirror.c | 3 +-- > block/qcow2.c | 8 ++------ > qemu-img.c | 10 ++++------ > 5 files changed, 41 insertions(+), 34 deletions(-) > > diff --git a/include/block/block_int.h b/include/block/block_int.h > index 55c5d573d4..7f71c585a0 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -202,10 +202,12 @@ struct BlockDriver { > int64_t offset, int bytes); > > /* > - * Building block for bdrv_block_status[_above]. The driver should > - * answer only according to the current layer, and should not > - * set BDRV_BLOCK_ALLOCATED, but may set BDRV_BLOCK_RAW. See block.h > - * for the meaning of _DATA, _ZERO, and _OFFSET_VALID. > + * Building block for bdrv_block_status[_above] and > + * bdrv_is_allocated[_above]. The driver should answer only > + * according to the current layer, and should not set > + * BDRV_BLOCK_ALLOCATED, but may set BDRV_BLOCK_RAW. See block.h > + * for the meaning of _DATA, _ZERO, and _OFFSET_VALID. The block > + * layer guarantees non-NULL pnum and file. > */ > int64_t coroutine_fn (*bdrv_co_get_block_status)(BlockDriverState *bs, > int64_t sector_num, int nb_sectors, int *pnum, > diff --git a/block/io.c b/block/io.c > index 8a0cd8835a..f250029395 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -695,7 +695,6 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags) > { > int64_t target_sectors, ret, nb_sectors, sector_num = 0; > BlockDriverState *bs = child->bs; > - BlockDriverState *file; > int n; > > target_sectors = bdrv_nb_sectors(bs); > @@ -708,7 +707,7 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags) > if (nb_sectors <= 0) { > return 0; > } > - ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, &file); > + ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, NULL); > if (ret < 0) { > error_report("error getting block status at sector %" PRId64 ": %s", > sector_num, strerror(-ret)); > @@ -1755,8 +1754,9 @@ int64_t coroutine_fn bdrv_co_get_block_status_from_backing(BlockDriverState *bs, > * beyond the end of the disk image it will be clamped; if 'pnum' is set to > * the end of the image, then the returned value will include BDRV_BLOCK_EOF. > * > - * If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file' > - * points to the BDS which the sector range is allocated in. > + * If returned value is positive, BDRV_BLOCK_OFFSET_VALID bit is set, and > + * 'file' is non-NULL, then '*file' points to the BDS which the sector range > + * is allocated in. > */ > static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > int64_t sector_num, > @@ -1766,15 +1766,22 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > int64_t total_sectors; > int64_t n; > int64_t ret, ret2; > + BlockDriverState *local_file = NULL; > > - *file = NULL; > + assert(pnum); nice assert.. > total_sectors = bdrv_nb_sectors(bs); > if (total_sectors < 0) { > + if (file) { > + *file = NULL; > + } Function reads slightly worse for the wear now with all of the return logic handled at various places within, but unifying it might be even stranger, perhaps.. Let's see if I hate this more: out: bdrv_dec_in_flight(bs); bdrv_dec_in_flight(bs); if (ret >= 0 && sector_num + *pnum == total_sectors) { ret |= BDRV_BLOCK_EOF; } early_out: if (file) { *file = local_file; } return ret; and then earlier in the function, we can just: if (total_sectors < 0) { ret = total_sectors; goto early_out; } > return total_sectors; > } > > if (sector_num >= total_sectors) { > *pnum = 0; > + if (file) { > + *file = NULL; > + } ret = BDRV_BLOCK_EOF; goto early_out; > return BDRV_BLOCK_EOF; > } > > @@ -1791,23 +1798,27 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > } > if (bs->drv->protocol_name) { > ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE); > - *file = bs; > + if (file) { > + *file = bs; > + } local_file = bs; > + } else if (file) { > + *file = NULL; no longer needed > } > return ret; replaced with: goto early_out; > } > > bdrv_inc_in_flight(bs); > ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum, > - file); > + &local_file); > if (ret < 0) { > *pnum = 0; > goto out; > } > > if (ret & BDRV_BLOCK_RAW) { > - assert(ret & BDRV_BLOCK_OFFSET_VALID && *file); > - ret = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS, > - *pnum, pnum, file); > + assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file); > + ret = bdrv_co_get_block_status(local_file, ret >> BDRV_SECTOR_BITS, > + *pnum, pnum, &local_file); > goto out; > } > > @@ -1825,14 +1836,13 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > } > } > > - if (*file && *file != bs && > + if (local_file && local_file != bs && > (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) && > (ret & BDRV_BLOCK_OFFSET_VALID)) { > - BlockDriverState *file2; > int file_pnum; > > - ret2 = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS, > - *pnum, &file_pnum, &file2); > + ret2 = bdrv_co_get_block_status(local_file, ret >> BDRV_SECTOR_BITS, > + *pnum, &file_pnum, NULL); > if (ret2 >= 0) { > /* Ignore errors. This is just providing extra information, it > * is useful but not necessary. > @@ -1854,6 +1864,9 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > } > > out: > + if (file) { > + *file = local_file; > + } > bdrv_dec_in_flight(bs); > if (ret >= 0 && sector_num + *pnum == total_sectors) { > ret |= BDRV_BLOCK_EOF; > @@ -1957,7 +1970,6 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, > int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset, > int64_t bytes, int64_t *pnum) > { > - BlockDriverState *file; > int64_t sector_num = offset >> BDRV_SECTOR_BITS; > int nb_sectors = bytes >> BDRV_SECTOR_BITS; > int64_t ret; > @@ -1966,7 +1978,7 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset, > assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); > assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE) && bytes < INT_MAX); > ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &psectors, > - &file); > + NULL); > if (ret < 0) { > return ret; > } > diff --git a/block/mirror.c b/block/mirror.c > index 5cdaaed7be..032cfe91fa 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -390,7 +390,6 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > int io_sectors; > unsigned int io_bytes; > int64_t io_bytes_acct; > - BlockDriverState *file; > enum MirrorMethod { > MIRROR_METHOD_COPY, > MIRROR_METHOD_ZERO, > @@ -401,7 +400,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > ret = bdrv_get_block_status_above(source, NULL, > offset >> BDRV_SECTOR_BITS, > nb_chunks * sectors_per_chunk, > - &io_sectors, &file); > + &io_sectors, NULL); > io_bytes = io_sectors * BDRV_SECTOR_SIZE; > if (ret < 0) { > io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); > diff --git a/block/qcow2.c b/block/qcow2.c > index 64dcd98a91..9a7b5cd41f 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -2975,7 +2975,6 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t start, > uint32_t count) > { > int nr; > - BlockDriverState *file; > int64_t res; > > if (start + count > bs->total_sectors) { > @@ -2985,8 +2984,7 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t start, > if (!count) { > return true; > } > - res = bdrv_get_block_status_above(bs, NULL, start, count, > - &nr, &file); > + res = bdrv_get_block_status_above(bs, NULL, start, count, &nr, NULL); > return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == count; > } > > @@ -3654,13 +3652,11 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, > offset += pnum * BDRV_SECTOR_SIZE) { > int nb_sectors = MIN(ssize - offset, > BDRV_REQUEST_MAX_BYTES) / BDRV_SECTOR_SIZE; > - BlockDriverState *file; > int64_t ret; > > ret = bdrv_get_block_status_above(in_bs, NULL, > offset >> BDRV_SECTOR_BITS, > - nb_sectors, > - &pnum, &file); > + nb_sectors, &pnum, NULL); > if (ret < 0) { > error_setg_errno(&local_err, -ret, > "Unable to get block status"); > diff --git a/qemu-img.c b/qemu-img.c > index df984b11b9..0c12e1c240 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -1374,7 +1374,6 @@ static int img_compare(int argc, char **argv) > > for (;;) { > int64_t status1, status2; > - BlockDriverState *file; > > nb_sectors = sectors_to_process(total_sectors, sector_num); > if (nb_sectors <= 0) { > @@ -1382,7 +1381,7 @@ static int img_compare(int argc, char **argv) > } > status1 = bdrv_get_block_status_above(bs1, NULL, sector_num, > total_sectors1 - sector_num, > - &pnum1, &file); > + &pnum1, NULL); > if (status1 < 0) { > ret = 3; > error_report("Sector allocation test failed for %s", filename1); > @@ -1392,7 +1391,7 @@ static int img_compare(int argc, char **argv) > > status2 = bdrv_get_block_status_above(bs2, NULL, sector_num, > total_sectors2 - sector_num, > - &pnum2, &file); > + &pnum2, NULL); > if (status2 < 0) { > ret = 3; > error_report("Sector allocation test failed for %s", filename2); > @@ -1598,15 +1597,14 @@ 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) { > - BlockDriverState *file; > if (s->target_has_backing) { > ret = bdrv_get_block_status(blk_bs(s->src[src_cur]), > sector_num - src_cur_offset, > - n, &n, &file); > + n, &n, NULL); > } else { > ret = bdrv_get_block_status_above(blk_bs(s->src[src_cur]), NULL, > sector_num - src_cur_offset, > - n, &n, &file); > + n, &n, NULL); > } > if (ret < 0) { > return ret; > It's only shed paint, though: Reviewed-by: John Snow <jsnow@redhat.com> I'm looking at the rest of the series now, so please stand by.
On 09/25/2017 05:43 PM, John Snow wrote: > > > On 09/13/2017 12:03 PM, Eric Blake wrote: >> Not all callers care about which BDS owns the mapping for a given >> range of the file. This patch merely simplifies the callers by >> consolidating the logic in the common call point, while guaranteeing >> a non-NULL file to all the driver callbacks, for no semantic change. >> The only caller that does not care about pnum is bdrv_is_allocated, >> as invoked by vvfat; we can likewise add assertions that the rest >> of the stack does not have to worry about a NULL pnum. >> >> Furthermore, this will also set the stage for a future cleanup: when >> a caller does not care about which BDS owns an offset, it would be >> nice to allow the driver to optimize things to not have to return >> BDRV_BLOCK_OFFSET_VALID in the first place. In the case of fragmented >> allocation (for example, it's fairly easy to create a qcow2 image >> where consecutive guest addresses are not at consecutive host >> addresses), the current contract requires bdrv_get_block_status() >> to clamp *pnum to the limit where host addresses are no longer >> consecutive, but allowing a NULL file means that *pnum could be >> set to the full length of known-allocated data. >> > > Function reads slightly worse for the wear now with all of the return > logic handled at various places within, but unifying it might be even > stranger, perhaps.. > > Let's see if I hate this more: > > out: > bdrv_dec_in_flight(bs); > bdrv_dec_in_flight(bs); > if (ret >= 0 && sector_num + *pnum == total_sectors) { > ret |= BDRV_BLOCK_EOF; > } > early_out: > if (file) { > *file = local_file; > } > return ret; > > > and then earlier in the function, we can just: > > if (total_sectors < 0) { > ret = total_sectors; > goto early_out; > } Seems reasonable enough, I'll work that in to v5, since there are other reasons to respin the series anyway. > > It's only shed paint, though: > > Reviewed-by: John Snow <jsnow@redhat.com> > > I'm looking at the rest of the series now, so please stand by. >
diff --git a/include/block/block_int.h b/include/block/block_int.h index 55c5d573d4..7f71c585a0 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -202,10 +202,12 @@ struct BlockDriver { int64_t offset, int bytes); /* - * Building block for bdrv_block_status[_above]. The driver should - * answer only according to the current layer, and should not - * set BDRV_BLOCK_ALLOCATED, but may set BDRV_BLOCK_RAW. See block.h - * for the meaning of _DATA, _ZERO, and _OFFSET_VALID. + * Building block for bdrv_block_status[_above] and + * bdrv_is_allocated[_above]. The driver should answer only + * according to the current layer, and should not set + * BDRV_BLOCK_ALLOCATED, but may set BDRV_BLOCK_RAW. See block.h + * for the meaning of _DATA, _ZERO, and _OFFSET_VALID. The block + * layer guarantees non-NULL pnum and file. */ int64_t coroutine_fn (*bdrv_co_get_block_status)(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum, diff --git a/block/io.c b/block/io.c index 8a0cd8835a..f250029395 100644 --- a/block/io.c +++ b/block/io.c @@ -695,7 +695,6 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags) { int64_t target_sectors, ret, nb_sectors, sector_num = 0; BlockDriverState *bs = child->bs; - BlockDriverState *file; int n; target_sectors = bdrv_nb_sectors(bs); @@ -708,7 +707,7 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags) if (nb_sectors <= 0) { return 0; } - ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, &file); + ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, NULL); if (ret < 0) { error_report("error getting block status at sector %" PRId64 ": %s", sector_num, strerror(-ret)); @@ -1755,8 +1754,9 @@ int64_t coroutine_fn bdrv_co_get_block_status_from_backing(BlockDriverState *bs, * beyond the end of the disk image it will be clamped; if 'pnum' is set to * the end of the image, then the returned value will include BDRV_BLOCK_EOF. * - * If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file' - * points to the BDS which the sector range is allocated in. + * If returned value is positive, BDRV_BLOCK_OFFSET_VALID bit is set, and + * 'file' is non-NULL, then '*file' points to the BDS which the sector range + * is allocated in. */ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, int64_t sector_num, @@ -1766,15 +1766,22 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, int64_t total_sectors; int64_t n; int64_t ret, ret2; + BlockDriverState *local_file = NULL; - *file = NULL; + assert(pnum); total_sectors = bdrv_nb_sectors(bs); if (total_sectors < 0) { + if (file) { + *file = NULL; + } return total_sectors; } if (sector_num >= total_sectors) { *pnum = 0; + if (file) { + *file = NULL; + } return BDRV_BLOCK_EOF; } @@ -1791,23 +1798,27 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, } if (bs->drv->protocol_name) { ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE); - *file = bs; + if (file) { + *file = bs; + } + } else if (file) { + *file = NULL; } return ret; } bdrv_inc_in_flight(bs); ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum, - file); + &local_file); if (ret < 0) { *pnum = 0; goto out; } if (ret & BDRV_BLOCK_RAW) { - assert(ret & BDRV_BLOCK_OFFSET_VALID && *file); - ret = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS, - *pnum, pnum, file); + assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file); + ret = bdrv_co_get_block_status(local_file, ret >> BDRV_SECTOR_BITS, + *pnum, pnum, &local_file); goto out; } @@ -1825,14 +1836,13 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, } } - if (*file && *file != bs && + if (local_file && local_file != bs && (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) && (ret & BDRV_BLOCK_OFFSET_VALID)) { - BlockDriverState *file2; int file_pnum; - ret2 = bdrv_co_get_block_status(*file, ret >> BDRV_SECTOR_BITS, - *pnum, &file_pnum, &file2); + ret2 = bdrv_co_get_block_status(local_file, ret >> BDRV_SECTOR_BITS, + *pnum, &file_pnum, NULL); if (ret2 >= 0) { /* Ignore errors. This is just providing extra information, it * is useful but not necessary. @@ -1854,6 +1864,9 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, } out: + if (file) { + *file = local_file; + } bdrv_dec_in_flight(bs); if (ret >= 0 && sector_num + *pnum == total_sectors) { ret |= BDRV_BLOCK_EOF; @@ -1957,7 +1970,6 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes, int64_t *pnum) { - BlockDriverState *file; int64_t sector_num = offset >> BDRV_SECTOR_BITS; int nb_sectors = bytes >> BDRV_SECTOR_BITS; int64_t ret; @@ -1966,7 +1978,7 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset, assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE) && bytes < INT_MAX); ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &psectors, - &file); + NULL); if (ret < 0) { return ret; } diff --git a/block/mirror.c b/block/mirror.c index 5cdaaed7be..032cfe91fa 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -390,7 +390,6 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) int io_sectors; unsigned int io_bytes; int64_t io_bytes_acct; - BlockDriverState *file; enum MirrorMethod { MIRROR_METHOD_COPY, MIRROR_METHOD_ZERO, @@ -401,7 +400,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) ret = bdrv_get_block_status_above(source, NULL, offset >> BDRV_SECTOR_BITS, nb_chunks * sectors_per_chunk, - &io_sectors, &file); + &io_sectors, NULL); io_bytes = io_sectors * BDRV_SECTOR_SIZE; if (ret < 0) { io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); diff --git a/block/qcow2.c b/block/qcow2.c index 64dcd98a91..9a7b5cd41f 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2975,7 +2975,6 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t start, uint32_t count) { int nr; - BlockDriverState *file; int64_t res; if (start + count > bs->total_sectors) { @@ -2985,8 +2984,7 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t start, if (!count) { return true; } - res = bdrv_get_block_status_above(bs, NULL, start, count, - &nr, &file); + res = bdrv_get_block_status_above(bs, NULL, start, count, &nr, NULL); return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == count; } @@ -3654,13 +3652,11 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, offset += pnum * BDRV_SECTOR_SIZE) { int nb_sectors = MIN(ssize - offset, BDRV_REQUEST_MAX_BYTES) / BDRV_SECTOR_SIZE; - BlockDriverState *file; int64_t ret; ret = bdrv_get_block_status_above(in_bs, NULL, offset >> BDRV_SECTOR_BITS, - nb_sectors, - &pnum, &file); + nb_sectors, &pnum, NULL); if (ret < 0) { error_setg_errno(&local_err, -ret, "Unable to get block status"); diff --git a/qemu-img.c b/qemu-img.c index df984b11b9..0c12e1c240 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1374,7 +1374,6 @@ static int img_compare(int argc, char **argv) for (;;) { int64_t status1, status2; - BlockDriverState *file; nb_sectors = sectors_to_process(total_sectors, sector_num); if (nb_sectors <= 0) { @@ -1382,7 +1381,7 @@ static int img_compare(int argc, char **argv) } status1 = bdrv_get_block_status_above(bs1, NULL, sector_num, total_sectors1 - sector_num, - &pnum1, &file); + &pnum1, NULL); if (status1 < 0) { ret = 3; error_report("Sector allocation test failed for %s", filename1); @@ -1392,7 +1391,7 @@ static int img_compare(int argc, char **argv) status2 = bdrv_get_block_status_above(bs2, NULL, sector_num, total_sectors2 - sector_num, - &pnum2, &file); + &pnum2, NULL); if (status2 < 0) { ret = 3; error_report("Sector allocation test failed for %s", filename2); @@ -1598,15 +1597,14 @@ 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) { - BlockDriverState *file; if (s->target_has_backing) { ret = bdrv_get_block_status(blk_bs(s->src[src_cur]), sector_num - src_cur_offset, - n, &n, &file); + n, &n, NULL); } else { ret = bdrv_get_block_status_above(blk_bs(s->src[src_cur]), NULL, sector_num - src_cur_offset, - n, &n, &file); + n, &n, NULL); } if (ret < 0) { return ret;
Not all callers care about which BDS owns the mapping for a given range of the file. This patch merely simplifies the callers by consolidating the logic in the common call point, while guaranteeing a non-NULL file to all the driver callbacks, for no semantic change. The only caller that does not care about pnum is bdrv_is_allocated, as invoked by vvfat; we can likewise add assertions that the rest of the stack does not have to worry about a NULL pnum. Furthermore, this will also set the stage for a future cleanup: when a caller does not care about which BDS owns an offset, it would be nice to allow the driver to optimize things to not have to return BDRV_BLOCK_OFFSET_VALID in the first place. In the case of fragmented allocation (for example, it's fairly easy to create a qcow2 image where consecutive guest addresses are not at consecutive host addresses), the current contract requires bdrv_get_block_status() to clamp *pnum to the limit where host addresses are no longer consecutive, but allowing a NULL file means that *pnum could be set to the full length of known-allocated data. Signed-off-by: Eric Blake <eblake@redhat.com> --- v4: only context changes v3: rebase to recent changes (qcow2_measure), dropped R-b v2: use local variable and final transfer, rather than assignment of parameter to local [previously in different series]: v2: new patch, https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg05645.html --- include/block/block_int.h | 10 ++++++---- block/io.c | 44 ++++++++++++++++++++++++++++---------------- block/mirror.c | 3 +-- block/qcow2.c | 8 ++------ qemu-img.c | 10 ++++------ 5 files changed, 41 insertions(+), 34 deletions(-)