Re: [PATCH 4/6] vhost: refactor VDUSE reconnection log mapping

[David Marchand <david.marchand@redhat.com>]

On Wed, Oct 23, 2024 at 5:16 PM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
>
> This patch moves the VDUSE reconnection log mapping, as
> well as creation if needed, into a dedicated function.
>
> This is a preliminary rework to simplify VDUSE device
> creation.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/vhost/vduse.c | 138 +++++++++++++++++++++++++---------------------
>  1 file changed, 75 insertions(+), 63 deletions(-)
>
> diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
> index c8c4761293..985d4cc58d 100644
> --- a/lib/vhost/vduse.c
> +++ b/lib/vhost/vduse.c
> @@ -431,6 +431,9 @@ vduse_reconnect_path_init(void)
>         const char *directory;
>         int ret;
>
> +       if (vduse_reconnect_path_set == true)
> +               return 0;
> +
>         /* from RuntimeDirectory= see systemd.exec */
>         directory = getenv("RUNTIME_DIRECTORY");
>         if (directory == NULL) {
> @@ -462,9 +465,74 @@ vduse_reconnect_path_init(void)
>         VHOST_CONFIG_LOG("vduse", INFO, "Created VDUSE reconnect directory in %s",
>                         vduse_reconnect_dir);
>
> +       vduse_reconnect_path_set = true;
> +
>         return 0;
>  }
>
> +static int
> +vduse_reconnect_log_map(const char *dev_name, struct vhost_reconnect_data **reco_log, bool create)

You can pass struct virtio_net *dev instead of patch 6.


> +{
> +       char reco_file[PATH_MAX];
> +       int fd, ret;
> +
> +       if (vduse_reconnect_path_init() < 0) {
> +               VHOST_CONFIG_LOG(dev_name, ERR, "Failed to initialize reconnect path");
> +                       return -1;

Weird indent.


> +       }
> +
> +       ret = snprintf(reco_file, sizeof(reco_file), "%s/%s", vduse_reconnect_dir, dev_name);
> +       if (ret < 0 || ret == sizeof(reco_file)) {
> +               VHOST_CONFIG_LOG(dev_name, ERR, "Failed to create vduse reconnect path name");
> +               return -1;
> +       }
> +
> +       if (create) {
> +               fd = open(reco_file, O_CREAT | O_EXCL | O_RDWR, 0600);
> +               if (fd < 0) {
> +                       if (errno == EEXIST) {
> +                               VHOST_CONFIG_LOG(dev_name, ERR, "Reconnect file %s exists but not the device",
> +                                               reco_file);
> +                       } else {
> +                               VHOST_CONFIG_LOG(dev_name, ERR, "Failed to open reconnect file %s (%s)",
> +                                               reco_file, strerror(errno));
> +                       }
> +                       return -1;
> +               }
> +
> +               ret = ftruncate(fd, sizeof(**reco_log));
> +               if (ret < 0) {
> +                       VHOST_CONFIG_LOG(dev_name, ERR, "Failed to truncate reconnect file %s (%s)",
> +                                       reco_file, strerror(errno));
> +                       goto out_close;
> +               }
> +       } else {
> +               fd = open(reco_file, O_RDWR, 0600);
> +               if (fd < 0) {
> +                       if (errno == ENOENT)
> +                               VHOST_CONFIG_LOG(dev_name, ERR, "Missing reconnect file (%s)", reco_file);
> +                       else
> +                               VHOST_CONFIG_LOG(dev_name, ERR, "Failed to open reconnect file %s (%s)",
> +                                               reco_file, strerror(errno));
> +                       return -1;
> +               }
> +       }
> +
> +       *reco_log = mmap(NULL, sizeof(**reco_log), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> +       if (*reco_log == MAP_FAILED) {
> +               VHOST_CONFIG_LOG(dev_name, ERR, "Failed to mmap reconnect file %s (%s)",
> +                               reco_file, strerror(errno));
> +               ret = -1;
> +               goto out_close;
> +       }
> +       ret = 0;
> +
> +out_close:
> +       close(fd);
> +
> +       return ret;
> +}
> +
>  static void
>  vduse_reconnect_handler(int fd, void *arg, int *remove)
>  {
> @@ -519,7 +587,7 @@ vduse_reconnect_start_device(struct virtio_net *dev)
>  int
>  vduse_device_create(const char *path, bool compliant_ol_flags)
>  {
> -       int control_fd, dev_fd, vid, ret, reco_fd;
> +       int control_fd, dev_fd, vid, ret;
>         uint32_t i, max_queue_pairs, total_queues;
>         struct virtio_net *dev;
>         struct virtio_net_config vnet_config = {{ 0 }};
> @@ -527,7 +595,6 @@ vduse_device_create(const char *path, bool compliant_ol_flags)
>         uint64_t features;
>         struct vduse_dev_config *dev_config = NULL;
>         const char *name = path + strlen("/dev/vduse/");
> -       char reconnect_file[PATH_MAX];
>         struct vhost_reconnect_data *reconnect_log = MAP_FAILED;
>         bool reconnect = false;
>
> @@ -539,20 +606,6 @@ vduse_device_create(const char *path, bool compliant_ol_flags)
>                 }
>         }
>
> -       if (vduse_reconnect_path_set == false) {
> -               if (vduse_reconnect_path_init() < 0) {
> -                       VHOST_CONFIG_LOG(path, ERR, "failed to initialize reconnect path");
> -                       return -1;
> -               }
> -               vduse_reconnect_path_set = true;
> -       }
> -
> -       ret = snprintf(reconnect_file, sizeof(reconnect_file), "%s/%s", vduse_reconnect_dir, name);
> -       if (ret < 0 || ret == sizeof(reconnect_file)) {
> -               VHOST_CONFIG_LOG(name, ERR, "Failed to create vduse reconnect path name");
> -               return -1;
> -       }
> -
>         control_fd = open(VDUSE_CTRL_PATH, O_RDWR);
>         if (control_fd < 0) {
>                 VHOST_CONFIG_LOG(name, ERR, "Failed to open %s: %s",
> @@ -592,26 +645,10 @@ vduse_device_create(const char *path, bool compliant_ol_flags)
>                 VHOST_CONFIG_LOG(name, INFO, "Device already exists, reconnecting...");
>                 reconnect = true;
>
> -               reco_fd = open(reconnect_file, O_RDWR, 0600);
> -               if (reco_fd < 0) {
> -                       if (errno == ENOENT)
> -                               VHOST_CONFIG_LOG(name, ERR, "Missing reconnect file (%s)",
> -                                               reconnect_file);
> -                       else
> -                               VHOST_CONFIG_LOG(name, ERR, "Failed to open reconnect file %s (%s)",
> -                                               reconnect_file, strerror(errno));
> -                       ret = -1;
> -                       goto out_dev_close;
> -               }
> -
> -               reconnect_log = mmap(NULL, sizeof(*reconnect_log), PROT_READ | PROT_WRITE,
> -                               MAP_SHARED, reco_fd, 0);
> -               close(reco_fd);
> -               if (reconnect_log == MAP_FAILED) {
> -                       VHOST_CONFIG_LOG(name, ERR, "Failed to mmap reconnect file %s (%s)",
> -                                       reconnect_file, strerror(errno));
> -                       ret = -1;
> -                       goto out_dev_close;
> +               ret = vduse_reconnect_log_map(name, &reconnect_log, false);
> +               if (ret < 0) {
> +                       VHOST_CONFIG_LOG(name, ERR, "Failed to map reconnect log file");

No additional log, all error cases are covered, afaics.



> +                       goto out_ctrl_close;
>                 }
>
>                 if (reconnect_log->version != VHOST_RECONNECT_VERSION) {


-- 
David Marchand