Message ID | 1413887956-28027-1-git-send-email-roger.pau@citrix.com |
---|---|
State | New |
Headers | show |
On 2014-10-21 at 12:39, Roger Pau Monne wrote: > Introduce a new flag to mark devices that require requests to be aligned 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 flag > unconditionally. > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > Cc: Kevin Wolf <kwolf@redhat.com> > Cc: Stefan Hajnoczi <stefanha@redhat.com> > --- > 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 needs > 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 field here? :-/ I know and see that there is pre-existing code here which does it, but I 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 *bs, int fd, Error **errp) > > /* 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 = 1; > s->buf_align = 1; > return; > @@ -446,6 +447,8 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, > > s->has_discard = true; > s->has_write_zeroes = true; > + if ((bs->open_flags & BDRV_O_NOCACHE) != 0) > + s->needs_alignement = true; This is not conforming to the qemu coding style (always put {} around 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, QDict *options, > } > #endif > } > +#ifdef __FreeBSD__ > + if (S_ISCHR(st.st_mode)) { > + /* > + * The file is a char device (disk), which on FreeBSD isn't behind > + * a pager, so force all requests to be aligned. This is needed > + * so Qemu makes sure all IO operations on the device are aligned > + * to sector size, or else FreeBSD will reject them with EINVAL. > + */ > + s->needs_alignement = true; > + } > +#endif > > #ifdef CONFIG_XFS > if (platform_test_xfs_fd(s->fd)) { > @@ -1076,11 +1090,12 @@ static BlockDriverAIOCB *raw_aio_submit(BlockDriverState *bs, > return NULL; > > /* > - * 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 |= QEMU_AIO_MISALIGNED; > #ifdef CONFIG_LINUX_AIO With s/alignement/alignment/ and the conditional block changed to conform to the qemu coding style: Reviewed-by: Max Reitz <mreitz@redhat.com> You are free to keep needs_alignment a bit field or not (the R-b stands either way). I wouldn't make it a bit field but I leave it up to you. Max
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; #ifdef CONFIG_FIEMAP bool skip_fiemap; #endif @@ -230,7 +231,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) /* 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 = 1; s->buf_align = 1; return; @@ -446,6 +447,8 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, s->has_discard = true; s->has_write_zeroes = true; + if ((bs->open_flags & BDRV_O_NOCACHE) != 0) + s->needs_alignement = true; 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, QDict *options, } #endif } +#ifdef __FreeBSD__ + if (S_ISCHR(st.st_mode)) { + /* + * The file is a char device (disk), which on FreeBSD isn't behind + * a pager, so force all requests to be aligned. This is needed + * so Qemu makes sure all IO operations on the device are aligned + * to sector size, or else FreeBSD will reject them with EINVAL. + */ + s->needs_alignement = true; + } +#endif #ifdef CONFIG_XFS if (platform_test_xfs_fd(s->fd)) { @@ -1076,11 +1090,12 @@ static BlockDriverAIOCB *raw_aio_submit(BlockDriverState *bs, return NULL; /* - * 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 |= QEMU_AIO_MISALIGNED; #ifdef CONFIG_LINUX_AIO
Introduce a new flag to mark devices that require requests to be aligned 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 flag unconditionally. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Cc: Kevin Wolf <kwolf@redhat.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> --- 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 needs requests to be aligned. --- block/raw-posix.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-)