From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58409) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCvvW-0007BT-KT for qemu-devel@nongnu.org; Tue, 14 Jun 2016 17:31:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bCvvP-0006uG-Fb for qemu-devel@nongnu.org; Tue, 14 Jun 2016 17:31:13 -0400 From: Eric Blake Date: Tue, 14 Jun 2016 15:30:28 -0600 Message-Id: <1465939839-30097-7-git-send-email-eblake@redhat.com> In-Reply-To: <1465939839-30097-1-git-send-email-eblake@redhat.com> References: <1465939839-30097-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v2 06/17] iscsi: Advertise realistic limits to block layer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, Ronnie Sahlberg , Paolo Bonzini , Peter Lieven , Max Reitz 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 --- v2: new patch --- block/iscsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/iscsi.c b/block/iscsi.c index 7e78ade..4290e41 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -1697,7 +1697,9 @@ 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) -- 2.5.5