[dm-devel] [PATCH V3 1/3] multipath-tools: Increase MAX_REPLY_LEN.

[Hannes Reinecke]

On 07/01/2016 02:46 PM, Gris Ge wrote:
> Problem:
> 
>     mpath_recv_reply() return -EINVA with 2k paths.
> 
> Root cause:
> 
>     With 2k paths(1k mpaths) simulated by scsi_debug, the 'show maps json'
>     requires 1633217 bytes while MAX_REPLY_LEN is 65535 bytes.
> 
> Fix:
> 
>     Increase MAX_REPLY_LEN to 10485760(10MiB) which is enough for 10k
>     paths.
> 
> Signed-off-by: Gris Ge <fge at redhat.com>
> ---
>  libmpathcmd/mpath_cmd.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/libmpathcmd/mpath_cmd.h b/libmpathcmd/mpath_cmd.h
> index f33f000..d65c648 100644
> --- a/libmpathcmd/mpath_cmd.h
> +++ b/libmpathcmd/mpath_cmd.h
> @@ -28,7 +28,9 @@ extern "C" {
>  
>  #define DEFAULT_SOCKET		"/org/kernel/linux/storage/multipathd"
>  #define DEFAULT_REPLY_TIMEOUT	1000
> -#define MAX_REPLY_LEN		65536
> +#define MAX_REPLY_LEN		10485760
> +/* ^ 10 MiB, enough for 'show maps json' command with 10k paths which
> + *   requires about 8 MiB */
>  
>  
Huh.
Can't say I like it. The limit is pretty much self-imposed, so I'd
rather bite the bullet and make it size-independent.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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