From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42049) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKSd7-0000kg-DR for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKSd6-0006Uc-9m for qemu-devel@nongnu.org; Tue, 05 Jul 2016 11:51:21 -0400 From: Kevin Wolf Date: Tue, 5 Jul 2016 17:50:16 +0200 Message-Id: <1467733852-27097-8-git-send-email-kwolf@redhat.com> In-Reply-To: <1467733852-27097-1-git-send-email-kwolf@redhat.com> References: <1467733852-27097-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 07/43] iscsi: Advertise realistic limits to block layer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Eric Blake The function sector_limits_lun2qemu() returns a value in units of the block layer's 512-byte sector, and can be as large as 0x40000000, which is much larger than the block layer's inherent limit of BDRV_REQUEST_MAX_SECTORS. The block layer already handles '0' as a synonym to the inherent limit, and it is nicer to return this value than it is to calculate an arbitrary maximum, for two reasons: we want to ensure that the block layer continues to special-case '0' as 'no limit beyond the inherent limits'; and we want to be able to someday expand the block layer to allow 64-bit limits, where auditing for uses of BDRV_REQUEST_MAX_SECTORS will help us make sure we aren't artificially constraining iscsi to old block layer limits. Signed-off-by: Eric Blake Reviewed-by: Kevin Wolf Reviewed-by: Fam Zheng Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/iscsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/iscsi.c b/block/iscsi.c index 9bb5ff6..c5dedb3 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -1698,7 +1698,9 @@ static void iscsi_close(BlockDriverState *bs) static int sector_limits_lun2qemu(int64_t sector, IscsiLun *iscsilun) { - return MIN(sector_lun2qemu(sector, iscsilun), INT_MAX / 2 + 1); + int limit = MIN(sector_lun2qemu(sector, iscsilun), INT_MAX / 2 + 1); + + return limit < BDRV_REQUEST_MAX_SECTORS ? limit : 0; } static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp) -- 1.8.3.1