[PATCH] libubi: ubi_update_start: slightly improve documentation

[Zhihao Cheng]

在 2024/7/10 19:29, Christian Eggers 写道:
> Calling ubi_update_start() may fail if exclusive access to the UBI
> volume cannot be established by the kernel. This is likely to happen if
> an UBI volume is updated directly after creation, because current
> versions of (systemd-)udevd run their internal 'blkid' also for UBI
> volumes as soon as they appear (trying to read the UBIFS UUID).
> 
> There are mainly to options for this case:
> 1. Don't allow udevd to read UBI volumes at all (means loosing
> functionatlity)
> 2. Wait until udevd has finished accessing a new volume (requires
> cooperation with udevd)
> 3. Simply retry after short time in case of EBUSY
> 
> For using option 3, the documentation should state that the concrete
> error code can be read via errno (this has always been the case since
> libubi has been introduced).
> 
> Link: https://groups.google.com/g/swupdate/c/8NVooKjD9oo
> Signed-off-by: Christian Eggers <ceggers at arri.de>
> ---

Reviewed-by: Zhihao Cheng <chengzhihao1 at huawei.com>

>   include/libubi.h | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/libubi.h b/include/libubi.h
> index e1e234e1b01b..9cb5037bb92a 100644
> --- a/include/libubi.h
> +++ b/include/libubi.h
> @@ -431,8 +431,8 @@ int ubi_vol_block_remove(int fd);
>    * @bytes: how many bytes will be written to the volume
>    *
>    * This function initiates UBI volume update and returns %0 in case of success
> - * and %-1 in case of error. The caller is assumed to write @bytes data to the
> - * volume @fd afterward.
> + * and %-1 in case of error (errno is set). The caller is assumed to write
> + * @bytes data to the volume @fd afterward.
>    */
>   int ubi_update_start(libubi_t desc, int fd, long long bytes);
>   
>