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

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 10/23/24 18:07, David Marchand wrote:
> 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.

At patch 4, the struct virtio_net *dev has not yet been allocated when
this function is called.

Or, maybe you mean I should squash patch 6 with this one?

> 
> 
>> +{
>> +       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.

Fixed.

> 
>> +       }
>> +
>> +       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.

Ack.

> 
> 
>> +                       goto out_ctrl_close;

and it should be out_dev_close here, will change in v2.

Thanks,
Maxime

>>                  }
>>
>>                  if (reconnect_log->version != VHOST_RECONNECT_VERSION) {
> 
>