From 5ae07b141085c9ac0e10b739639e760b71c490f2 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 11 Dec 2020 21:39:28 +0300 Subject: 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 Message-Id: <20201211183934.169161-11-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake Signed-off-by: Eric Blake --- block/io.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/block/io.c b/block/io.c index cb5064155b..98d9f5bdf4 100644 --- a/block/io.c +++ b/block/io.c @@ -41,7 +41,7 @@ static void bdrv_parent_cb_resize(BlockDriverState *bs); static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, - int64_t offset, int bytes, BdrvRequestFlags flags); + int64_t offset, int64_t bytes, BdrvRequestFlags flags); static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore, bool ignore_bds_parents) @@ -1819,7 +1819,7 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child, } static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, - int64_t offset, int bytes, BdrvRequestFlags flags) + int64_t offset, int64_t bytes, BdrvRequestFlags flags) { BlockDriver *drv = bs->drv; QEMUIOVector qiov; @@ -1834,6 +1834,8 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, bs->bl.request_alignment); int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER); + bdrv_check_request(offset, bytes, &error_abort); + if (!drv) { return -ENOMEDIUM; } @@ -1849,7 +1851,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, assert(max_write_zeroes >= bs->bl.request_alignment); while (bytes > 0 && !ret) { - int num = bytes; + int64_t num = bytes; /* Align request. Block drivers can expect the "bulk" of the request * to be aligned, and that unaligned requests do not cross cluster -- cgit v1.2.3-55-g7522