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block: char devices on FreeBSD are not behind a pager

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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>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Roger Pau Monne 2014-10-21 16:03:03 +02:00 committed by Max Reitz
parent 1b2dd0bee6
commit 3cad83075c
1 changed files with 21 additions and 5 deletions
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26
block/raw-posix.c
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@ -150,6 +150,7 @@ typedef struct BDRVRawState {
bool has_discard:1;
bool has_write_zeroes:1;
bool discard_zeroes:1;
bool needs_alignment;
#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_alignment) {
bs->request_alignment = 1;
s->buf_align = 1;
return;
@ -446,6 +447,9 @@ 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_alignment = true;
}
if (fstat(s->fd, &st) < 0) {
error_setg_errno(errp, errno, "Could not stat file");
@ -472,6 +476,17 @@ 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_alignment = true;
}
#endif
#ifdef CONFIG_XFS
if (platform_test_xfs_fd(s->fd)) {
@ -1076,11 +1091,12 @@ static BlockAIOCB *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_alignment) {
if (!bdrv_qiov_is_aligned(bs, qiov)) {
type |= QEMU_AIO_MISALIGNED;
#ifdef CONFIG_LINUX_AIO