| Message ID | 20201211183934.169161-14-vsementsov@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 64bit block-layer: part I | expand |
On 12/11/20 12:39 PM, Vladimir Sementsov-Ogievskiy wrote: > We are generally moving to int64_t for both offset and bytes parameters > on all io paths. > > Main motivation is realization of 64-bit write_zeroes operation for > fast zeroing large disk chunks, up to the whole disk. > > We chose signed type, to be consistent with off_t (which is signed) and > with possibility for signed return type (where negative value means > error). > > So, prepare bdrv_aligned_preadv() now. > > Make byte variable in bdrv_padding_rmw_read() int64_t, as it defined > only to be passed to bdrv_aligned_preadv(). Reads awkwardly, how about: Make the byte variable in bdrv_padding_rmw_read() int64_t, as it is only used for pass-through to bdrv_aligned_preadv(). > > All bdrv_aligned_preadv() callers are safe as type is widening. Let's > look inside: > > - add a new-style assertion that request is good. > - callees bdrv_is_allocated(), bdrv_co_do_copy_on_readv() supports > int64_t bytes > - conversion of bytes_remaining is OK, as we never has requests have > overflowing BDRV_MAX_LENGTH > - looping through bytes_remaining is ok, num is updated to int64_t > - for bdrv_driver_preadv we have same limit of max_transfer > - qemu_iovec_memset is OK, as bytes+qiov_offset should not overflow > qiov->size anyway (thanks to bdrv_check_qiov_request()) > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > --- > block/io.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > Reviewed-by: Eric Blake <eblake@redhat.com>
22.01.2021 19:54, Eric Blake wrote: > On 12/11/20 12:39 PM, Vladimir Sementsov-Ogievskiy wrote: >> We are generally moving to int64_t for both offset and bytes parameters >> on all io paths. >> >> Main motivation is realization of 64-bit write_zeroes operation for >> fast zeroing large disk chunks, up to the whole disk. >> >> We chose signed type, to be consistent with off_t (which is signed) and >> with possibility for signed return type (where negative value means >> error). >> >> So, prepare bdrv_aligned_preadv() now. >> >> Make byte variable in bdrv_padding_rmw_read() int64_t, as it defined >> only to be passed to bdrv_aligned_preadv(). > > Reads awkwardly, how about: > > Make the byte variable in bdrv_padding_rmw_read() int64_t, as it is only > used for pass-through to bdrv_aligned_preadv(). and also s/byte/bytes/ > >> >> All bdrv_aligned_preadv() callers are safe as type is widening. Let's >> look inside: >> >> - add a new-style assertion that request is good. >> - callees bdrv_is_allocated(), bdrv_co_do_copy_on_readv() supports >> int64_t bytes >> - conversion of bytes_remaining is OK, as we never has requests > > have > >> overflowing BDRV_MAX_LENGTH >> - looping through bytes_remaining is ok, num is updated to int64_t >> - for bdrv_driver_preadv we have same limit of max_transfer >> - qemu_iovec_memset is OK, as bytes+qiov_offset should not overflow >> qiov->size anyway (thanks to bdrv_check_qiov_request()) >> >> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >> --- >> block/io.c | 9 +++++---- >> 1 file changed, 5 insertions(+), 4 deletions(-) >> > > Reviewed-by: Eric Blake <eblake@redhat.com> >
diff --git a/block/io.c b/block/io.c index d8c07fac56..93a89a56e3 100644 --- a/block/io.c +++ b/block/io.c @@ -1453,15 +1453,16 @@ err: * reads; any other features must be implemented by the caller. */ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child, - BdrvTrackedRequest *req, int64_t offset, unsigned int bytes, + BdrvTrackedRequest *req, int64_t offset, int64_t bytes, int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags) { BlockDriverState *bs = child->bs; int64_t total_bytes, max_bytes; int ret = 0; - uint64_t bytes_remaining = bytes; + int64_t bytes_remaining = bytes; int max_transfer; + bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort); assert(is_power_of_2(align)); assert((offset & (align - 1)) == 0); assert((bytes & (align - 1)) == 0); @@ -1518,7 +1519,7 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child, } while (bytes_remaining) { - int num; + int64_t num; if (max_bytes) { num = MIN(bytes_remaining, MIN(max_bytes, max_transfer)); @@ -1624,7 +1625,7 @@ static int bdrv_padding_rmw_read(BdrvChild *child, assert(req->serialising && pad->buf); if (pad->head || pad->merge_reads) { - uint64_t bytes = pad->merge_reads ? pad->buf_len : align; + int64_t bytes = pad->merge_reads ? pad->buf_len : align; qemu_iovec_init_buf(&local_qiov, pad->buf, bytes);
We are generally moving to int64_t for both offset and bytes parameters on all io paths. Main motivation is realization of 64-bit write_zeroes operation for fast zeroing large disk chunks, up to the whole disk. We chose signed type, to be consistent with off_t (which is signed) and with possibility for signed return type (where negative value means error). So, prepare bdrv_aligned_preadv() now. Make byte variable in bdrv_padding_rmw_read() int64_t, as it defined only to be passed to bdrv_aligned_preadv(). All bdrv_aligned_preadv() callers are safe as type is widening. Let's look inside: - add a new-style assertion that request is good. - callees bdrv_is_allocated(), bdrv_co_do_copy_on_readv() supports int64_t bytes - conversion of bytes_remaining is OK, as we never has requests overflowing BDRV_MAX_LENGTH - looping through bytes_remaining is ok, num is updated to int64_t - for bdrv_driver_preadv we have same limit of max_transfer - qemu_iovec_memset is OK, as bytes+qiov_offset should not overflow qiov->size anyway (thanks to bdrv_check_qiov_request()) Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> --- block/io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)