From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59556) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cUJgR-0004Wi-CH for qemu-devel@nongnu.org; Thu, 19 Jan 2017 15:51:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cUJgP-00086E-3S for qemu-devel@nongnu.org; Thu, 19 Jan 2017 15:51:47 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:37383) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cUJgO-00085d-Pt for qemu-devel@nongnu.org; Thu, 19 Jan 2017 15:51:45 -0500 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0JKhneI056742 for ; Thu, 19 Jan 2017 15:51:43 -0500 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0a-001b2d01.pphosted.com with ESMTP id 282y7aq0rv-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 19 Jan 2017 15:51:42 -0500 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 19 Jan 2017 20:51:40 -0000 From: Eric Farman Date: Thu, 19 Jan 2017 21:51:34 +0100 In-Reply-To: <20170119205134.50112-1-farman@linux.vnet.ibm.com> References: <20170119205134.50112-1-farman@linux.vnet.ibm.com> Message-Id: <20170119205134.50112-4-farman@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH v2 3/3] block: get max_transfer limit for char (scsi-generic) devices List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: Eric Farman , kwolf@redhat.com, mreitz@redhat.com Commit 6f607174 introduced a routine to get the maximum number of bytes for a single I/O transfer for block devices, however scsi generic devices are character devices, not block. Add a condition for this, such that scsi generic devices can view the same data. Some tweaking of data is required, because the block and sg ioctls return values in different scales (sectors versus bytes). So adjust hdev_get_max_transfer_length such that it always returns a value in bytes. Signed-off-by: Eric Farman --- block/file-posix.c | 10 ++++++---- include/block/block.h | 1 + 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index 2115155..94068ca 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -657,9 +657,11 @@ static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd) int max_sectors = 0; short max_sectors_short = 0; if (bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) == 0) { + /* sg returns a value in bytes */ return max_sectors; } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors_short) == 0) { - return max_sectors_short; + /* block returns a value in sectors */ + return max_sectors_short << BDRV_SECTOR_BITS; } else { return -errno; } @@ -674,10 +676,10 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp) struct stat st; if (!fstat(s->fd, &st)) { - if (S_ISBLK(st.st_mode)) { + if (S_ISBLK(st.st_mode) || S_ISCHR(st.st_mode)) { int ret = hdev_get_max_transfer_length(bs, s->fd); - if (ret > 0 && ret <= BDRV_REQUEST_MAX_SECTORS) { - bs->bl.max_transfer = pow2floor(ret << BDRV_SECTOR_BITS); + if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { + bs->bl.max_transfer = pow2floor(ret); } } } diff --git a/include/block/block.h b/include/block/block.h index 8b0dcda..4e81f20 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -116,6 +116,7 @@ typedef struct HDGeometry { #define BDRV_REQUEST_MAX_SECTORS MIN(SIZE_MAX >> BDRV_SECTOR_BITS, \ INT_MAX >> BDRV_SECTOR_BITS) +#define BDRV_REQUEST_MAX_BYTES (BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS) /* * Allocation status flags -- 2.8.4