From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50493) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIfTc-0003nY-OX for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:33:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YIfTT-000094-FH for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:33:20 -0500 Received: from mx2.parallels.com ([199.115.105.18]:59620) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YIfTT-00008w-6z for qemu-devel@nongnu.org; Tue, 03 Feb 2015 10:33:11 -0500 Message-ID: <54D0EA2D.2070900@parallels.com> Date: Tue, 3 Feb 2015 18:33:01 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1422965567-8611-1-git-send-email-pl@kamp.de> <54D0CD54.9080309@parallels.com> <54D0DB80.4070004@kamp.de> In-Reply-To: <54D0DB80.4070004@kamp.de> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] block: introduce BDRV_REQUEST_MAX_SECTORS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven , qemu-devel@nongnu.org Cc: kwolf@redhat.com On 03/02/15 17:30, Peter Lieven wrote: > Am 03.02.2015 um 14:29 schrieb Denis V. Lunev: >> On 03/02/15 15:12, Peter Lieven wrote: >>> we check and adjust request sizes at several places with >>> sometimes inconsistent checks or default values: >>> INT_MAX >>> INT_MAX >> BDRV_SECTOR_BITS >>> UINT_MAX >> BDRV_SECTOR_BITS >>> SIZE_MAX >> BDRV_SECTOR_BITS >>> >>> This patches introdocues a macro for the maximal allowed sectors >>> per request and uses it at several places. >>> >>> Signed-off-by: Peter Lieven >>> --- >>> block.c | 19 ++++++++----------- >>> hw/block/virtio-blk.c | 4 ++-- >>> include/block/block.h | 3 +++ >>> 3 files changed, 13 insertions(+), 13 deletions(-) >>> >>> diff --git a/block.c b/block.c >>> index 8272ef9..4e58b35 100644 >>> --- a/block.c >>> +++ b/block.c >>> @@ -2671,7 +2671,7 @@ static int >>> bdrv_check_byte_request(BlockDriverState *bs, int64_t offset, >>> static int bdrv_check_request(BlockDriverState *bs, int64_t >>> sector_num, >>> int nb_sectors) >>> { >>> - if (nb_sectors < 0 || nb_sectors > INT_MAX / BDRV_SECTOR_SIZE) { >>> + if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) { >>> return -EIO; >>> } >>> @@ -2758,7 +2758,7 @@ static int bdrv_rw_co(BlockDriverState *bs, >>> int64_t sector_num, uint8_t *buf, >>> .iov_len = nb_sectors * BDRV_SECTOR_SIZE, >>> }; >>> - if (nb_sectors < 0 || nb_sectors > INT_MAX / BDRV_SECTOR_SIZE) { >>> + if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) { >>> return -EINVAL; >>> } >>> @@ -2826,13 +2826,10 @@ int bdrv_make_zero(BlockDriverState *bs, >>> BdrvRequestFlags flags) >>> } >>> for (;;) { >>> - nb_sectors = target_sectors - sector_num; >>> + nb_sectors = MIN(target_sectors - sector_num, >>> BDRV_REQUEST_MAX_SECTORS); >>> if (nb_sectors <= 0) { >>> return 0; >>> } >>> - if (nb_sectors > INT_MAX / BDRV_SECTOR_SIZE) { >>> - nb_sectors = INT_MAX / BDRV_SECTOR_SIZE; >>> - } >>> ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n); >>> if (ret < 0) { >>> error_report("error getting block status at sector %" >>> PRId64 ": %s", >>> @@ -3167,7 +3164,7 @@ static int coroutine_fn >>> bdrv_co_do_readv(BlockDriverState *bs, >>> int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, >>> BdrvRequestFlags flags) >>> { >>> - if (nb_sectors < 0 || nb_sectors > (UINT_MAX >> >>> BDRV_SECTOR_BITS)) { >>> + if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) { >>> return -EINVAL; >>> } >>> @@ -3202,8 +3199,8 @@ static int coroutine_fn >>> bdrv_co_do_write_zeroes(BlockDriverState *bs, >>> struct iovec iov = {0}; >>> int ret = 0; >>> - int max_write_zeroes = bs->bl.max_write_zeroes ? >>> - bs->bl.max_write_zeroes : INT_MAX; >>> + int max_write_zeroes = MIN_NON_ZERO(bs->bl.max_write_zeroes, >>> + BDRV_REQUEST_MAX_SECTORS); >>> while (nb_sectors > 0 && !ret) { >>> int num = nb_sectors; >>> @@ -3458,7 +3455,7 @@ static int coroutine_fn >>> bdrv_co_do_writev(BlockDriverState *bs, >>> int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, >>> BdrvRequestFlags flags) >>> { >>> - if (nb_sectors < 0 || nb_sectors > (INT_MAX >> >>> BDRV_SECTOR_BITS)) { >>> + if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) { >>> return -EINVAL; >>> } >>> @@ -5120,7 +5117,7 @@ int coroutine_fn >>> bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, >>> return 0; >>> } >>> - max_discard = bs->bl.max_discard ? bs->bl.max_discard : INT_MAX; >>> + max_discard = MIN_NON_ZERO(bs->bl.max_discard, >>> BDRV_REQUEST_MAX_SECTORS); >>> while (nb_sectors > 0) { >>> int ret; >>> int num = nb_sectors; >>> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c >>> index 8c51a29..1a8a176 100644 >>> --- a/hw/block/virtio-blk.c >>> +++ b/hw/block/virtio-blk.c >>> @@ -381,7 +381,7 @@ void virtio_blk_submit_multireq(BlockBackend >>> *blk, MultiReqBuffer *mrb) >>> } >>> max_xfer_len = >>> blk_get_max_transfer_length(mrb->reqs[0]->dev->blk); >>> - max_xfer_len = MIN_NON_ZERO(max_xfer_len, INT_MAX); >>> + max_xfer_len = MIN_NON_ZERO(max_xfer_len, >>> BDRV_REQUEST_MAX_SECTORS); >>> qsort(mrb->reqs, mrb->num_reqs, sizeof(*mrb->reqs), >>> &multireq_compare); >>> @@ -447,7 +447,7 @@ static bool virtio_blk_sect_range_ok(VirtIOBlock >>> *dev, >>> uint64_t nb_sectors = size >> BDRV_SECTOR_BITS; >>> uint64_t total_sectors; >>> - if (nb_sectors > INT_MAX) { >>> + if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) { >>> return false; >>> } >>> if (sector & dev->sector_mask) { >>> diff --git a/include/block/block.h b/include/block/block.h >>> index 3082d2b..25a6d62 100644 >>> --- a/include/block/block.h >>> +++ b/include/block/block.h >>> @@ -83,6 +83,9 @@ typedef enum { >>> #define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS) >>> #define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1) >>> +#define BDRV_REQUEST_MAX_SECTORS MIN(SIZE_MAX >> BDRV_SECTOR_BITS, \ >>> + INT_MAX >> BDRV_SECTOR_BITS) >>> + >>> /* >>> * Allocation status flags >>> * BDRV_BLOCK_DATA: data is read from bs->file or another file >> Reviewed-by: Denis V. Lunev >> >> On the other hand the limitation to INT_MAX for a request size >> (in bytes) is here. >> >> bdrv_check_byte_request >> if (size > INT_MAX) { >> return -EIO; >> } >> >> which means that all my patches from series >> [PATCH v3 0/2] fix max_discard for NBD/gluster block drivers >> becomes unnecessary but this was not that obvious before this >> clarification :) > > No, not completely. If we run into the check above the request fails. > If you set max_write_zeroes the request is appropiately trimmed. > So if the driver allows less than BDRV_REQUEST_MAX_SECTORS sectors > you still have to set it in the BlockLimits. > > Peter > your point will be correct after the following patch applied diff --git a/block.c b/block.c index 4e58b35..49e0073 100644 --- a/block.c +++ b/block.c @@ -2647,7 +2647,7 @@ static int bdrv_check_byte_request(BlockDriverState *bs, i { int64_t len; - if (size > INT_MAX) { + if (size > BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS) { return -EIO; } without we will fail at entry point inside bdrv_check_byte_request(). My patch applies the limit of UINT32_MAX over the value which is not greater than INT_MAX in the current codebase. bdrv_check_byte_request() is performed at the very-very beginning of the processing, f.e bdrv_co_discard bdrv_check_request bdrv_check_byte_request <-- (INT_MAX limit applied) max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS); Den