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authorRoger Pau Monne <roger.pau@citrix.com>2014-10-21 16:03:03 +0200
committerMax Reitz <mreitz@redhat.com>2014-10-23 16:56:53 +0200
commit3cad83075c7b847fe0eb6e61316fdf50984d4570 (patch)
treea286ce1b56987c52fd99bb6dff2079d8fc75ab81 /block
parent1b2dd0bee6bd03045b90c8a7549c8134466b2938 (diff)
block: char devices on FreeBSD are not behind a pager
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>
Diffstat (limited to 'block')
-rw-r--r--block/raw-posix.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/block/raw-posix.c b/block/raw-posix.c
index ee4ca3c01e..475cf74655 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_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