From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36492) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgXyQ-00007b-5s for qemu-devel@nongnu.org; Tue, 21 Oct 2014 07:51:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XgXyL-0003TH-5C for qemu-devel@nongnu.org; Tue, 21 Oct 2014 07:51:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2882) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgXyK-0003T6-U5 for qemu-devel@nongnu.org; Tue, 21 Oct 2014 07:51:29 -0400 Message-ID: <544648BB.4090408@redhat.com> Date: Tue, 21 Oct 2014 13:51:23 +0200 From: Max Reitz MIME-Version: 1.0 References: <1413887956-28027-1-git-send-email-roger.pau@citrix.com> In-Reply-To: <1413887956-28027-1-git-send-email-roger.pau@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2] block: char devices on FreeBSD are not behind a pager List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Roger Pau Monne , qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi On 2014-10-21 at 12:39, Roger Pau Monne wrote: > Introduce a new flag to mark devices that require requests to be aligne= d and > replace the usage of BDRV_O_NOCACHE and O_DIRECT with this flag when > appropriate. > > If a character device is used as a backend on a FreeBSD host set this f= lag > unconditionally. > > Signed-off-by: Roger Pau Monn=C3=A9 > Cc: Kevin Wolf > Cc: Stefan Hajnoczi > --- > Changes since v1: > - Intead of appending BDRV_O_NOCACHE and O_DIRECT when a char dev is = used > on FreeBSD introduce a new flag that is used to mark if a device ne= eds > requests to be aligned. > --- > block/raw-posix.c | 25 ++++++++++++++++++++----- > 1 file changed, 20 insertions(+), 5 deletions(-) > > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 86ce4f2..b5361f7 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -150,6 +150,7 @@ typedef struct BDRVRawState { > bool has_discard:1; > bool has_write_zeroes:1; > bool discard_zeroes:1; > + bool needs_alignement:1; First, it's "alignment". Second, urgh, do you really want to use a bit=20 field here? :-/ I know and see that there is pre-existing code here which does it, but I=20 personally find it pretty ugly. There is no need to use one whatsoever. > #ifdef CONFIG_FIEMAP > bool skip_fiemap; > #endif > @@ -230,7 +231,7 @@ static void raw_probe_alignment(BlockDriverState *b= s, int fd, Error **errp) > =20 > /* For /dev/sg devices the alignment is not really used. > With buffered I/O, we don't have any restrictions. */ > - if (bs->sg || !(s->open_flags & O_DIRECT)) { > + if (bs->sg || !s->needs_alignement) { > bs->request_alignment =3D 1; > s->buf_align =3D 1; > return; > @@ -446,6 +447,8 @@ static int raw_open_common(BlockDriverState *bs, QD= ict *options, > =20 > s->has_discard =3D true; > s->has_write_zeroes =3D true; > + if ((bs->open_flags & BDRV_O_NOCACHE) !=3D 0) > + s->needs_alignement =3D true; This is not conforming to the qemu coding style (always put {} around=20 blocks). > if (fstat(s->fd, &st) < 0) { > error_setg_errno(errp, errno, "Could not stat file"); > @@ -472,6 +475,17 @@ static int raw_open_common(BlockDriverState *bs, Q= Dict *options, > } > #endif > } > +#ifdef __FreeBSD__ > + if (S_ISCHR(st.st_mode)) { > + /* > + * The file is a char device (disk), which on FreeBSD isn't be= hind > + * a pager, so force all requests to be aligned. This is neede= d > + * so Qemu makes sure all IO operations on the device are alig= ned > + * to sector size, or else FreeBSD will reject them with EINVA= L. > + */ > + s->needs_alignement =3D true; > + } > +#endif > =20 > #ifdef CONFIG_XFS > if (platform_test_xfs_fd(s->fd)) { > @@ -1076,11 +1090,12 @@ static BlockDriverAIOCB *raw_aio_submit(BlockDr= iverState *bs, > return NULL; > =20 > /* > - * If O_DIRECT is used the buffer needs to be aligned on a sector > - * boundary. Check if this is the case or tell the low-level > - * driver that it needs to copy the buffer. > + * Check if the underlying device requires requests to be aligned, > + * and if the request we are trying to submit is aligned or not. > + * If this is the case tell the low-level driver that it needs > + * to copy the buffer. > */ > - if ((bs->open_flags & BDRV_O_NOCACHE)) { > + if (s->needs_alignement) { > if (!bdrv_qiov_is_aligned(bs, qiov)) { > type |=3D QEMU_AIO_MISALIGNED; > #ifdef CONFIG_LINUX_AIO With s/alignement/alignment/ and the conditional block changed to=20 conform to the qemu coding style: Reviewed-by: Max Reitz You are free to keep needs_alignment a bit field or not (the R-b stands=20 either way). I wouldn't make it a bit field but I leave it up to you. Max