disk/aio: Refactor AIO code

Move all AIO code to a separate file, disk/aio.c, to remove as much
#ifdefs as possible. Split the raw read/write disk ops into async and
sync, and choose which ones to use depending on CONFIG_HAS_AIO. Note that
we fix raw_image__close() which incorrectly checked CONFIG_HAS_VIRTIO
instead of CONFIG_HAS_AIO, and closed an unitialized disk->evt. A
subsequent commit will complete this refactoring by fixing use of the
'async' disk attribute.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

7 files changed, 167 insertions, 125 deletions

diff --git a/Makefile b/Makefile
index 25f13a0f..3862112c 100644
--- a/Makefile
+++ b/Makefile
@@ -276,10 +276,12 @@ endif
 ifeq ($(call try-build,$(SOURCE_AIO),$(CFLAGS),$(LDFLAGS) -laio),y)
 	CFLAGS_DYNOPT	+= -DCONFIG_HAS_AIO
 	LIBS_DYNOPT	+= -laio
+	OBJS_DYNOPT	+= disk/aio.o
 else
 	ifeq ($(call try-build,$(SOURCE_AIO),$(CFLAGS),$(LDFLAGS) -laio -static),y)
 		CFLAGS_STATOPT	+= -DCONFIG_HAS_AIO
 		LIBS_STATOPT	+= -laio
+		OBJS_STATOPT	+= disk/aio.o
 	else
 		NOTFOUND	+= aio
 	endif
diff --git a/disk/aio.c b/disk/aio.c
new file mode 100644
index 00000000..6afcffe5
--- /dev/null
+++ b/disk/aio.c
@@ -0,0 +1,111 @@
+#include <libaio.h>
+#include <pthread.h>
+#include <sys/eventfd.h>
+
+#include "kvm/disk-image.h"
+#include "kvm/kvm.h"
+#include "linux/list.h"
+
+#define AIO_MAX 256
+
+static int aio_pwritev(io_context_t ctx, struct iocb *iocb, int fd,
+		       const struct iovec *iov, int iovcnt, off_t offset,
+		       int ev, void *param)
+{
+	struct iocb *ios[1] = { iocb };
+	int ret;
+
+	io_prep_pwritev(iocb, fd, iov, iovcnt, offset);
+	io_set_eventfd(iocb, ev);
+	iocb->data = param;
+
+restart:
+	ret = io_submit(ctx, 1, ios);
+	if (ret == -EAGAIN)
+		goto restart;
+	return ret;
+}
+
+static int aio_preadv(io_context_t ctx, struct iocb *iocb, int fd,
+		      const struct iovec *iov, int iovcnt, off_t offset,
+		      int ev, void *param)
+{
+	struct iocb *ios[1] = { iocb };
+	int ret;
+
+	io_prep_preadv(iocb, fd, iov, iovcnt, offset);
+	io_set_eventfd(iocb, ev);
+	iocb->data = param;
+
+restart:
+	ret = io_submit(ctx, 1, ios);
+	if (ret == -EAGAIN)
+		goto restart;
+	return ret;
+}
+
+ssize_t raw_image__read_async(struct disk_image *disk, u64 sector,
+			      const struct iovec *iov, int iovcount,
+			      void *param)
+{
+	u64 offset = sector << SECTOR_SHIFT;
+	struct iocb iocb;
+
+	return aio_preadv(disk->ctx, &iocb, disk->fd, iov, iovcount,
+			  offset, disk->evt, param);
+}
+
+ssize_t raw_image__write_async(struct disk_image *disk, u64 sector,
+			       const struct iovec *iov, int iovcount,
+			       void *param)
+{
+	u64 offset = sector << SECTOR_SHIFT;
+	struct iocb iocb;
+
+	return aio_pwritev(disk->ctx, &iocb, disk->fd, iov, iovcount,
+			   offset, disk->evt, param);
+}
+
+static void *disk_aio_thread(void *param)
+{
+	struct disk_image *disk = param;
+	struct io_event event[AIO_MAX];
+	struct timespec notime = {0};
+	int nr, i;
+	u64 dummy;
+
+	kvm__set_thread_name("disk-image-io");
+
+	while (read(disk->evt, &dummy, sizeof(dummy)) > 0) {
+		nr = io_getevents(disk->ctx, 1, ARRAY_SIZE(event), event, &notime);
+		for (i = 0; i < nr; i++)
+			disk->disk_req_cb(event[i].data, event[i].res);
+	}
+
+	return NULL;
+}
+
+int disk_aio_setup(struct disk_image *disk)
+{
+	int r;
+	pthread_t thread;
+
+	disk->evt = eventfd(0, 0);
+	if (disk->evt < 0)
+		return -errno;
+
+	io_setup(AIO_MAX, &disk->ctx);
+	r = pthread_create(&thread, NULL, disk_aio_thread, disk);
+	if (r) {
+		r = -errno;
+		close(disk->evt);
+		return r;
+	}
+	return 0;
+}
+
+void disk_aio_destroy(struct disk_image *disk)
+{
+	close(disk->evt);
+	io_destroy(disk->ctx);
+}
diff --git a/disk/core.c b/disk/core.c
index 4c7c4f03..89880703 100644
--- a/disk/core.c
+++ b/disk/core.c
@@ -4,11 +4,8 @@
 #include "kvm/kvm.h"
 
 #include <linux/err.h>
-#include <sys/eventfd.h>
 #include <poll.h>
 
-#define AIO_MAX 256
-
 int debug_iodelay;
 
 static int disk_image__close(struct disk_image *disk);
@@ -54,27 +51,6 @@ int disk_img_name_parser(const struct option *opt, const char *arg, int unset)
 	return 0;
 }
 
-#ifdef CONFIG_HAS_AIO
-static void *disk_image__thread(void *param)
-{
-	struct disk_image *disk = param;
-	struct io_event event[AIO_MAX];
-	struct timespec notime = {0};
-	int nr, i;
-	u64 dummy;
-
-	kvm__set_thread_name("disk-image-io");
-
-	while (read(disk->evt, &dummy, sizeof(dummy)) > 0) {
-		nr = io_getevents(disk->ctx, 1, ARRAY_SIZE(event), event, &notime);
-		for (i = 0; i < nr; i++)
-			disk->disk_req_cb(event[i].data, event[i].res);
-	}
-
-	return NULL;
-}
-#endif
-
 struct disk_image *disk_image__new(int fd, u64 size,
 				   struct disk_image_operations *ops,
 				   int use_mmap)
@@ -99,26 +75,22 @@ struct disk_image *disk_image__new(int fd, u64 size,
 		disk->priv = mmap(NULL, size, PROT_RW, MAP_PRIVATE | MAP_NORESERVE, fd, 0);
 		if (disk->priv == MAP_FAILED) {
 			r = -errno;
-			free(disk);
-			return ERR_PTR(r);
+			goto err_free_disk;
 		}
 	}
 
-#ifdef CONFIG_HAS_AIO
-	{
-		pthread_t thread;
+	r = disk_aio_setup(disk);
+	if (r)
+		goto err_unmap_disk;
 
-		disk->evt = eventfd(0, 0);
-		io_setup(AIO_MAX, &disk->ctx);
-		r = pthread_create(&thread, NULL, disk_image__thread, disk);
-		if (r) {
-			r = -errno;
-			free(disk);
-			return ERR_PTR(r);
-		}
-	}
-#endif
 	return disk;
+
+err_unmap_disk:
+	if (disk->priv)
+		munmap(disk->priv, size);
+err_free_disk:
+	free(disk);
+	return ERR_PTR(r);
 }
 
 static struct disk_image *disk_image__open(const char *filename, bool readonly, bool direct)
@@ -243,6 +215,8 @@ static int disk_image__close(struct disk_image *disk)
 	if (!disk)
 		return 0;
 
+	disk_aio_destroy(disk);
+
 	if (disk->ops->close)
 		return disk->ops->close(disk);
 
diff --git a/disk/raw.c b/disk/raw.c
index 93b2b4e8..09da7e08 100644
--- a/disk/raw.c
+++ b/disk/raw.c
@@ -2,38 +2,17 @@
 
 #include <linux/err.h>
 
-#ifdef CONFIG_HAS_AIO
-#include <libaio.h>
-#endif
-
-ssize_t raw_image__read(struct disk_image *disk, u64 sector, const struct iovec *iov,
+ssize_t raw_image__read_sync(struct disk_image *disk, u64 sector, const struct iovec *iov,
 				int iovcount, void *param)
 {
-	u64 offset = sector << SECTOR_SHIFT;
-
-#ifdef CONFIG_HAS_AIO
-	struct iocb iocb;
-
-	return aio_preadv(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
-				disk->evt, param);
-#else
-	return preadv_in_full(disk->fd, iov, iovcount, offset);
-#endif
+	return preadv_in_full(disk->fd, iov, iovcount, sector << SECTOR_SHIFT);
 }
 
-ssize_t raw_image__write(struct disk_image *disk, u64 sector, const struct iovec *iov,
-				int iovcount, void *param)
+ssize_t raw_image__write_sync(struct disk_image *disk, u64 sector,
+			      const struct iovec *iov, int iovcount,
+			      void *param)
 {
-	u64 offset = sector << SECTOR_SHIFT;
-
-#ifdef CONFIG_HAS_AIO
-	struct iocb iocb;
-
-	return aio_pwritev(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
-				disk->evt, param);
-#else
-	return pwritev_in_full(disk->fd, iov, iovcount, offset);
-#endif
+	return pwritev_in_full(disk->fd, iov, iovcount, sector << SECTOR_SHIFT);
 }
 
 ssize_t raw_image__read_mmap(struct disk_image *disk, u64 sector, const struct iovec *iov,
@@ -79,12 +58,6 @@ int raw_image__close(struct disk_image *disk)
 	if (disk->priv != MAP_FAILED)
 		ret = munmap(disk->priv, disk->size);
 
-	close(disk->evt);
-
-#ifdef CONFIG_HAS_VIRTIO
-	io_destroy(disk->ctx);
-#endif
-
 	return ret;
 }
 
diff --git a/include/kvm/disk-image.h b/include/kvm/disk-image.h
index 4746e88c..953beb2d 100644
--- a/include/kvm/disk-image.h
+++ b/include/kvm/disk-image.h
@@ -19,6 +19,10 @@
 #include <unistd.h>
 #include <fcntl.h>
 
+#ifdef CONFIG_HAS_AIO
+#include <libaio.h>
+#endif
+
 #define SECTOR_SHIFT		9
 #define SECTOR_SIZE		(1UL << SECTOR_SHIFT)
 
@@ -61,10 +65,10 @@ struct disk_image {
 	void				(*disk_req_cb)(void *param, long len);
 	bool				readonly;
 	bool				async;
-	int				evt;
 #ifdef CONFIG_HAS_AIO
 	io_context_t			ctx;
-#endif
+	int				evt;
+#endif /* CONFIG_HAS_AIO */
 	const char			*wwpn;
 	const char			*tpgt;
 	int				debug_iodelay;
@@ -84,14 +88,39 @@ ssize_t disk_image__get_serial(struct disk_image *disk, void *buffer, ssize_t *l
 struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly);
 struct disk_image *blkdev__probe(const char *filename, int flags, struct stat *st);
 
-ssize_t raw_image__read(struct disk_image *disk, u64 sector,
-				const struct iovec *iov, int iovcount, void *param);
-ssize_t raw_image__write(struct disk_image *disk, u64 sector,
-				const struct iovec *iov, int iovcount, void *param);
+ssize_t raw_image__read_sync(struct disk_image *disk, u64 sector,
+			     const struct iovec *iov, int iovcount, void *param);
+ssize_t raw_image__write_sync(struct disk_image *disk, u64 sector,
+			      const struct iovec *iov, int iovcount, void *param);
 ssize_t raw_image__read_mmap(struct disk_image *disk, u64 sector,
 				const struct iovec *iov, int iovcount, void *param);
 ssize_t raw_image__write_mmap(struct disk_image *disk, u64 sector,
 				const struct iovec *iov, int iovcount, void *param);
 int raw_image__close(struct disk_image *disk);
 void disk_image__set_callback(struct disk_image *disk, void (*disk_req_cb)(void *param, long len));
+
+#ifdef CONFIG_HAS_AIO
+int disk_aio_setup(struct disk_image *disk);
+void disk_aio_destroy(struct disk_image *disk);
+ssize_t raw_image__read_async(struct disk_image *disk, u64 sector,
+			      const struct iovec *iov, int iovcount, void *param);
+ssize_t raw_image__write_async(struct disk_image *disk, u64 sector,
+			       const struct iovec *iov, int iovcount, void *param);
+
+#define raw_image__read		raw_image__read_async
+#define raw_image__write	raw_image__write_async
+
+#else /* !CONFIG_HAS_AIO */
+static inline int disk_aio_setup(struct disk_image *disk)
+{
+	/* No-op */
+	return 0;
+}
+static inline void disk_aio_destroy(struct disk_image *disk)
+{
+}
+#define raw_image__read		raw_image__read_sync
+#define raw_image__write	raw_image__write_sync
+#endif /* CONFIG_HAS_AIO */
+
 #endif /* KVM__DISK_IMAGE_H */
diff --git a/include/kvm/read-write.h b/include/kvm/read-write.h
index acbd6f0b..8375d7c7 100644
--- a/include/kvm/read-write.h
+++ b/include/kvm/read-write.h
@@ -5,10 +5,6 @@
 #include <sys/uio.h>
 #include <unistd.h>
 
-#ifdef CONFIG_HAS_AIO
-#include <libaio.h>
-#endif
-
 ssize_t xread(int fd, void *buf, size_t count);
 ssize_t xwrite(int fd, const void *buf, size_t count);
 
@@ -35,11 +31,4 @@ ssize_t xpwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset);
 ssize_t preadv_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset);
 ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offset);
 
-#ifdef CONFIG_HAS_AIO
-int aio_preadv(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
-		off_t offset, int ev, void *param);
-int aio_pwritev(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
-		off_t offset, int ev, void *param);
-#endif
-
 #endif /* KVM_READ_WRITE_H */
diff --git a/util/read-write.c b/util/read-write.c
index bf6fb2fc..06fc0dff 100644
--- a/util/read-write.c
+++ b/util/read-write.c
@@ -337,39 +337,3 @@ ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offse
 
 	return total;
 }
-
-#ifdef CONFIG_HAS_AIO
-int aio_pwritev(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
-		off_t offset, int ev, void *param)
-{
-	struct iocb *ios[1] = { iocb };
-	int ret;
-
-	io_prep_pwritev(iocb, fd, iov, iovcnt, offset);
-	io_set_eventfd(iocb, ev);
-	iocb->data = param;
-
-restart:
-	ret = io_submit(ctx, 1, ios);
-	if (ret == -EAGAIN)
-		goto restart;
-	return ret;
-}
-
-int aio_preadv(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
-		off_t offset, int ev, void *param)
-{
-	struct iocb *ios[1] = { iocb };
-	int ret;
-
-	io_prep_preadv(iocb, fd, iov, iovcnt, offset);
-	io_set_eventfd(iocb, ev);
-	iocb->data = param;
-
-restart:
-	ret = io_submit(ctx, 1, ios);
-	if (ret == -EAGAIN)
-		goto restart;
-	return ret;
-}
-#endif