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block: Switch transfer length bounds to byte-based

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Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_transfer_length
and opt_transfer_length.  Rename them (dropping the _length suffix)
so that the compiler will help us catch the change in semantics
across any rebased code, and improve the documentation.  Use unsigned
values, so that we don't have to worry about negative values and
so that bit-twiddling is easier; however, we are still constrained
by 2^31 of signed int in most APIs.

When a value comes from an external source (iscsi and raw-posix),
sanitize the results to ensure that opt_transfer is a power of 2.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2016-06-23 16:37:19 -06:00 • committed by Kevin Wolf
parent 79ba8c986a
commit 5def6b80e1
10 changed files with 57 additions and 47 deletions
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8
qemu-img.c
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@ -2085,13 +2085,13 @@ static int img_convert(int argc, char **argv)
}
out_bs = blk_bs(out_blk);
/* increase bufsectors from the default 4096 (2M) if opt_transfer_length
/* increase bufsectors from the default 4096 (2M) if opt_transfer
* or discard_alignment of the out_bs is greater. Limit to 32768 (16MB)
* as maximum. */
bufsectors = MIN(32768,
MAX(bufsectors, MAX(out_bs->bl.opt_transfer_length,
out_bs->bl.discard_alignment))
);
MAX(bufsectors,
MAX(out_bs->bl.opt_transfer >> BDRV_SECTOR_BITS,
out_bs->bl.discard_alignment)));
if (skip_create) {
int64_t output_sectors = blk_nb_sectors(out_blk);