Add an 'async' attribute to disk_image_operations, that describes if they
can submit async I/O or not. disk_image->async is now set iff
CONFIG_HAS_AIO and the ops do use AIO.
This fixes qcow1, which used to set async = 1 even though the qcow
operations don't use AIO. The disk core would perform the read/write
operation without pushing the completion onto the virtio queue, and the
guest would be stuck waiting.
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
disk/aio.c | 9 +++++++++
disk/blk.c | 9 ++-------
disk/qcow.c | 2 --
disk/raw.c | 15 +++------------
include/kvm/disk-image.h | 1 +
5 files changed, 15 insertions(+), 21 deletions(-)
diff --git a/disk/aio.c b/disk/aio.c
index 6afcffe5a..007415c69 100644
--- a/disk/aio.c
+++ b/disk/aio.c
@@ -90,6 +90,10 @@ int disk_aio_setup(struct disk_image *disk)
int r;
pthread_t thread;
+ /* No need to setup AIO if the disk ops won't make use of it */
+ if (!disk->ops->async)
+ return 0;
+
disk->evt = eventfd(0, 0);
if (disk->evt < 0)
return -errno;
@@ -101,11 +105,16 @@ int disk_aio_setup(struct disk_image *disk)
close(disk->evt);
return r;
}
+
+ disk->async = true;
return 0;
}
void disk_aio_destroy(struct disk_image *disk)
{
+ if (!disk->async)
+ return;
+
close(disk->evt);
io_destroy(disk->ctx);
}
diff --git a/disk/blk.c b/disk/blk.c
index 37581d331..48922e028 100644
--- a/disk/blk.c
+++ b/disk/blk.c
@@ -9,6 +9,7 @@
static struct disk_image_operations blk_dev_ops = {
.read = raw_image__read,
.write = raw_image__write,
+ .async = true,
};
static bool is_mounted(struct stat *st)
@@ -35,7 +36,6 @@ static bool is_mounted(struct stat *st)
struct disk_image *blkdev__probe(const char *filename, int flags, struct stat *st)
{
- struct disk_image *disk;
int fd, r;
u64 size;
@@ -67,10 +67,5 @@ struct disk_image *blkdev__probe(const char *filename, int flags, struct stat *s
* mmap large disk. There is not enough virtual address space
* in 32-bit host. However, this works on 64-bit host.
*/
- disk = disk_image__new(fd, size, &blk_dev_ops, DISK_IMAGE_REGULAR);
-#ifdef CONFIG_HAS_AIO
- if (!IS_ERR_OR_NULL(disk))
- disk->async = 1;
-#endif
- return disk;
+ return disk_image__new(fd, size, &blk_dev_ops, DISK_IMAGE_REGULAR);
}
diff --git a/disk/qcow.c b/disk/qcow.c
index bed70c65c..dd6be62ee 100644
--- a/disk/qcow.c
+++ b/disk/qcow.c
@@ -1337,7 +1337,6 @@ static struct disk_image *qcow2_probe(int fd, bool readonly)
if (IS_ERR_OR_NULL(disk_image))
goto free_refcount_table;
- disk_image->async = 0;
disk_image->priv = q;
return disk_image;
@@ -1474,7 +1473,6 @@ static struct disk_image *qcow1_probe(int fd, bool readonly)
if (!disk_image)
goto free_l1_table;
- disk_image->async = 1;
disk_image->priv = q;
return disk_image;
diff --git a/disk/raw.c b/disk/raw.c
index 09da7e081..e869d6cc2 100644
--- a/disk/raw.c
+++ b/disk/raw.c
@@ -67,6 +67,7 @@ int raw_image__close(struct disk_image *disk)
static struct disk_image_operations raw_image_regular_ops = {
.read = raw_image__read,
.write = raw_image__write,
+ .async = true,
};
struct disk_image_operations ro_ops = {
@@ -77,12 +78,11 @@ struct disk_image_operations ro_ops = {
struct disk_image_operations ro_ops_nowrite = {
.read = raw_image__read,
+ .async = true,
};
struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
{
- struct disk_image *disk;
-
if (readonly) {
/*
* Use mmap's MAP_PRIVATE to implement non-persistent write
@@ -93,10 +93,6 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
disk = disk_image__new(fd, st->st_size, &ro_ops, DISK_IMAGE_MMAP);
if (IS_ERR_OR_NULL(disk)) {
disk = disk_image__new(fd, st->st_size, &ro_ops_nowrite, DISK_IMAGE_REGULAR);
-#ifdef CONFIG_HAS_AIO
- if (!IS_ERR_OR_NULL(disk))
- disk->async = 1;
-#endif
}
return disk;
@@ -104,11 +100,6 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
/*
* Use read/write instead of mmap
*/
- disk = disk_image__new(fd, st->st_size, &raw_image_regular_ops, DISK_IMAGE_REGULAR);
-#ifdef CONFIG_HAS_AIO
- if (!IS_ERR_OR_NULL(disk))
- disk->async = 1;
-#endif
- return disk;
+ return disk_image__new(fd, st->st_size, &raw_image_regular_ops, DISK_IMAGE_REGULAR);
}
}
diff --git a/include/kvm/disk-image.h b/include/kvm/disk-image.h
index 953beb2d5..adc9fe465 100644
--- a/include/kvm/disk-image.h
+++ b/include/kvm/disk-image.h
@@ -42,6 +42,7 @@ struct disk_image_operations {
int iovcount, void *param);
int (*flush)(struct disk_image *disk);
int (*close)(struct disk_image *disk);
+ bool async;
};
struct disk_image_params {
--
2.21.0
