From 8b0c5d7659f0d0c192f78867f4dc6026e9f3506f Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 11 Dec 2020 21:39:31 +0300 Subject: [PATCH] block/io: support int64_t bytes in bdrv_aligned_preadv() 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 the bytes 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 have 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 Message-Id: <20201211183934.169161-14-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake [eblake: grammar tweak] Signed-off-by: Eric Blake --- block/io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/block/io.c b/block/io.c index 63b0fa0e9ed7..cef284e3a189 100644 --- a/block/io.c +++ b/block/io.c @@ -1475,15 +1475,16 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, * 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); @@ -1545,7 +1546,7 @@ 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)); @@ -1652,7 +1653,7 @@ 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);