diff options
| author | Eric Blake <eblake@redhat.com> | 2016-06-23 16:37:19 -0600 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2016-07-05 16:46:25 +0200 |
| commit | 5def6b80e1eca696c1fc6099e7f4d36729686402 (patch) | |
| tree | 5948b16242a3b57bb1dffa6c650ef05e9154f59e /block/io.c | |
| parent | 79ba8c986adb9ca07f52abd0b3d33c3aee8e6ff9 (diff) | |
block: Switch transfer length bounds to byte-based
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>
Diffstat (limited to 'block/io.c')
| -rw-r--r-- | block/io.c | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/block/io.c b/block/io.c index 323e822dd4..8ca9d43724 100644 --- a/block/io.c +++ b/block/io.c @@ -88,8 +88,8 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) error_propagate(errp, local_err); return; } - bs->bl.opt_transfer_length = bs->file->bs->bl.opt_transfer_length; - bs->bl.max_transfer_length = bs->file->bs->bl.max_transfer_length; + bs->bl.opt_transfer = bs->file->bs->bl.opt_transfer; + bs->bl.max_transfer = bs->file->bs->bl.max_transfer; bs->bl.min_mem_alignment = bs->file->bs->bl.min_mem_alignment; bs->bl.opt_mem_alignment = bs->file->bs->bl.opt_mem_alignment; bs->bl.max_iov = bs->file->bs->bl.max_iov; @@ -107,12 +107,10 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp) error_propagate(errp, local_err); return; } - bs->bl.opt_transfer_length = - MAX(bs->bl.opt_transfer_length, - bs->backing->bs->bl.opt_transfer_length); - bs->bl.max_transfer_length = - MIN_NON_ZERO(bs->bl.max_transfer_length, - bs->backing->bs->bl.max_transfer_length); + bs->bl.opt_transfer = MAX(bs->bl.opt_transfer, + bs->backing->bs->bl.opt_transfer); + bs->bl.max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, + bs->backing->bs->bl.max_transfer); bs->bl.opt_mem_alignment = MAX(bs->bl.opt_mem_alignment, bs->backing->bs->bl.opt_mem_alignment); @@ -1156,7 +1154,8 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0); } -#define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768 +/* Maximum buffer for write zeroes fallback, in bytes */ +#define MAX_WRITE_ZEROES_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS) static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int count, BdrvRequestFlags flags) @@ -1214,7 +1213,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, if (ret == -ENOTSUP) { /* Fall back to bounce buffer if write zeroes is unsupported */ - int max_xfer_len = MIN_NON_ZERO(bs->bl.max_transfer_length, + int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_WRITE_ZEROES_BOUNCE_BUFFER); BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE; @@ -1225,7 +1224,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, write_flags &= ~BDRV_REQ_FUA; need_flush = true; } - num = MIN(num, max_xfer_len << BDRV_SECTOR_BITS); + num = MIN(num, max_transfer); iov.iov_len = num; if (iov.iov_base == NULL) { iov.iov_base = qemu_try_blockalign(bs, num); @@ -1242,7 +1241,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, /* Keep bounce buffer around if it is big enough for all * all future requests. */ - if (num < max_xfer_len << BDRV_SECTOR_BITS) { + if (num < max_transfer) { qemu_vfree(iov.iov_base); iov.iov_base = NULL; } |