block/io: support int64_t bytes in bdrv_co_do_pwrite_zeroes()
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_co_do_pwrite_zeroes() now. Callers are safe, as converting int to int64_t is safe. Concentrate on 'bytes' usage in the function (thx to Eric Blake): compute 'int tail' via % 'int alignment' - safe fragmentation loop 'int num' - still fragments with a cap on max_transfer use of 'num' within the loop MIN(bytes, max_transfer) as well as %alignment - still works, so calculations in if (head) {} are safe clamp size by 'int max_write_zeroes' - safe drv->bdrv_co_pwrite_zeroes(int) - safe because of clamping clamp size by 'int max_transfer' - safe buf allocation is still clamped to max_transfer qemu_iovec_init_buf(size_t) - safe because of clamping bdrv_driver_pwritev(uint64_t) - safe Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20201211183934.169161-11-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
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@ -41,7 +41,7 @@
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static void bdrv_parent_cb_resize(BlockDriverState *bs);
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static void bdrv_parent_cb_resize(BlockDriverState *bs);
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static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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int64_t offset, int bytes, BdrvRequestFlags flags);
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int64_t offset, int64_t bytes, BdrvRequestFlags flags);
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static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,
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static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore,
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bool ignore_bds_parents)
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bool ignore_bds_parents)
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@ -1819,7 +1819,7 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
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}
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}
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static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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int64_t offset, int bytes, BdrvRequestFlags flags)
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int64_t offset, int64_t bytes, BdrvRequestFlags flags)
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{
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{
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BlockDriver *drv = bs->drv;
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BlockDriver *drv = bs->drv;
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QEMUIOVector qiov;
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QEMUIOVector qiov;
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@ -1834,6 +1834,8 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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bs->bl.request_alignment);
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bs->bl.request_alignment);
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int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER);
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int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER);
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bdrv_check_request(offset, bytes, &error_abort);
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if (!drv) {
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if (!drv) {
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return -ENOMEDIUM;
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return -ENOMEDIUM;
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}
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}
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@ -1849,7 +1851,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
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assert(max_write_zeroes >= bs->bl.request_alignment);
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assert(max_write_zeroes >= bs->bl.request_alignment);
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while (bytes > 0 && !ret) {
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while (bytes > 0 && !ret) {
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int num = bytes;
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int64_t num = bytes;
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/* Align request. Block drivers can expect the "bulk" of the request
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/* Align request. Block drivers can expect the "bulk" of the request
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* to be aligned, and that unaligned requests do not cross cluster
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* to be aligned, and that unaligned requests do not cross cluster
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