hw/9pfs: Add new virtfs option writeout=immediate skip host page cache
writeout=immediate implies the after pwritev we do a sync_file_range.
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 9559ff6..47295b7 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -203,16 +203,30 @@
static ssize_t local_pwritev(FsContext *ctx, int fd, const struct iovec *iov,
int iovcnt, off_t offset)
{
+ ssize_t ret
+;
#ifdef CONFIG_PREADV
- return pwritev(fd, iov, iovcnt, offset);
+ ret = pwritev(fd, iov, iovcnt, offset);
#else
int err = lseek(fd, offset, SEEK_SET);
if (err == -1) {
return err;
} else {
- return writev(fd, iov, iovcnt);
+ ret = writev(fd, iov, iovcnt);
}
#endif
+#ifdef CONFIG_SYNC_FILE_RANGE
+ if (ret > 0 && ctx->export_flags & V9FS_IMMEDIATE_WRITEOUT) {
+ /*
+ * Initiate a writeback. This is not a data integrity sync.
+ * We want to ensure that we don't leave dirty pages in the cache
+ * after write when writeout=immediate is sepcified.
+ */
+ sync_file_range(fd, offset, ret,
+ SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
+ }
+#endif
+ return ret;
}
static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
