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.
However, 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 <ebl...@redhat.com> --- v2: new patch --- block/io.c | 15 +++++++++------ block/mirror.c | 3 +-- block/qcow2.c | 4 +--- qemu-img.c | 10 ++++------ 4 files changed, 15 insertions(+), 17 deletions(-) diff --git a/block/io.c b/block/io.c index 8e6c3fe..eea74cb 100644 --- a/block/io.c +++ b/block/io.c @@ -706,7 +706,6 @@ 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); @@ -719,7 +718,7 @@ 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)); @@ -1737,8 +1736,9 @@ typedef struct BdrvCoGetBlockStatusData { * 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes * beyond the end of the disk image it will be clamped. * - * 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, @@ -1748,7 +1748,11 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, int64_t total_sectors; int64_t n; int64_t ret, ret2; + BlockDriverState *tmpfile; + if (!file) { + file = &tmpfile; + } *file = NULL; total_sectors = bdrv_nb_sectors(bs); if (total_sectors < 0) { @@ -1916,9 +1920,8 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { - BlockDriverState *file; int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum, - &file); + NULL); if (ret < 0) { return ret; } diff --git a/block/mirror.c b/block/mirror.c index e86f8f8..4563ba7 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -392,7 +392,6 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) while (nb_chunks > 0 && sector_num < end) { int64_t ret; int io_sectors, io_sectors_acct; - BlockDriverState *file; enum MirrorMethod { MIRROR_METHOD_COPY, MIRROR_METHOD_ZERO, @@ -402,7 +401,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) assert(!(sector_num % sectors_per_chunk)); ret = bdrv_get_block_status_above(source, NULL, sector_num, nb_chunks * sectors_per_chunk, - &io_sectors, &file); + &io_sectors, NULL); if (ret < 0) { io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors); } else if (ret & BDRV_BLOCK_DATA) { diff --git a/block/qcow2.c b/block/qcow2.c index b3ba5da..8e9e29b 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2448,7 +2448,6 @@ 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) { @@ -2458,8 +2457,7 @@ 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; } diff --git a/qemu-img.c b/qemu-img.c index 5aef8ef..cb78696 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1398,7 +1398,6 @@ 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) { @@ -1406,7 +1405,7 @@ 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); @@ -1416,7 +1415,7 @@ 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); @@ -1615,15 +1614,14 @@ 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; -- 2.9.4