From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cX6qw-00052E-8X for qemu-devel@nongnu.org; Fri, 27 Jan 2017 08:46:14 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cX6qv-000409-EK for qemu-devel@nongnu.org; Fri, 27 Jan 2017 08:46:10 -0500 Received: from mail-wm0-x244.google.com ([2a00:1450:400c:c09::244]:34373) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cX6qv-0003z1-7p for qemu-devel@nongnu.org; Fri, 27 Jan 2017 08:46:09 -0500 Received: by mail-wm0-x244.google.com with SMTP id c85so58232393wmi.1 for ; Fri, 27 Jan 2017 05:46:09 -0800 (PST) Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 27 Jan 2017 14:45:24 +0100 Message-Id: <1485524749-118532-17-git-send-email-pbonzini@redhat.com> In-Reply-To: <1485524749-118532-1-git-send-email-pbonzini@redhat.com> References: <1485524749-118532-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 16/41] block: Fix target variable of BLKSECTGET ioctl List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Eric Farman From: Eric Farman Commit 6f6071745bd0 ("raw-posix: Fetch max sectors for host block device") introduced a routine to call the kernel BLKSECTGET ioctl, which stores the result back to user space. However, the size of the data returned depends on the routine handling the ioctl. The (compat_)blkdev_ioctl returns a short, while sg_ioctl returns an int. Thus, on big-endian systems, we can find ourselves accidentally shifting the result to a much larger value. (On s390x, a short is 16 bits while an int is 32 bits.) Also, the two ioctl handlers return values in different scales (block returns sectors, while sg returns bytes), so some tweaking of the outputs is required such that hdev_get_max_transfer_length returns a value in a consistent set of units. Signed-off-by: Eric Farman Message-Id: <20170120162527.66075-3-farman@linux.vnet.ibm.com> Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- block/file-posix.c | 17 ++++++++++------- include/block/block.h | 1 + 2 files changed, 11 insertions(+), 7 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index 28b47d9..9f83725 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -651,12 +651,15 @@ static void raw_reopen_abort(BDRVReopenState *state) state->opaque = NULL; } -static int hdev_get_max_transfer_length(int fd) +static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd) { #ifdef BLKSECTGET - int max_sectors = 0; - if (ioctl(fd, BLKSECTGET, &max_sectors) == 0) { - return max_sectors; + int max_bytes = 0; + short max_sectors = 0; + if (bs->sg && ioctl(fd, BLKSECTGET, &max_bytes) == 0) { + return max_bytes; + } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) == 0) { + return max_sectors << BDRV_SECTOR_BITS; } else { return -errno; } @@ -672,9 +675,9 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp) if (!fstat(s->fd, &st)) { if (S_ISBLK(st.st_mode)) { - int ret = hdev_get_max_transfer_length(s->fd); - if (ret > 0 && ret <= BDRV_REQUEST_MAX_SECTORS) { - bs->bl.max_transfer = pow2floor(ret << BDRV_SECTOR_BITS); + int ret = hdev_get_max_transfer_length(bs, s->fd); + 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 -- 1.8.3.1