[dpdk-dev] [PATCH RESEND] eal: allow hugetlbfs sub-directories

[Dmitry Kozlyuk]

2021-06-25 11:44 (UTC+0100), John Levon:
> get_hugepage_dir() was implemented in such a way that a --huge-dir option
> had to exactly match the mountpoint, but there's no reason for this
> restriction. Fix the implementation to allow a sub-directory within a
> suitable hugetlbfs mountpoint to be specified.
> 
> Signed-off-by: John Levon <john.levon at nutanix.com>
> ---
>  lib/eal/linux/eal_hugepage_info.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/eal/linux/eal_hugepage_info.c b/lib/eal/linux/eal_hugepage_info.c
> index d97792cad..d7e9918f8 100644
> --- a/lib/eal/linux/eal_hugepage_info.c
> +++ b/lib/eal/linux/eal_hugepage_info.c
> @@ -226,16 +226,29 @@ get_hugepage_dir(uint64_t hugepage_sz, char *hugedir, int len)
>  		default_size = get_default_hp_size();
>  
>  	while (fgets(buf, sizeof(buf), fd)){
> +		const char *dir;
> +
>  		if (rte_strsplit(buf, sizeof(buf), splitstr, _FIELDNAME_MAX,
>  				split_tok) != _FIELDNAME_MAX) {
>  			RTE_LOG(ERR, EAL, "Error parsing %s\n", proc_mounts);
>  			break; /* return NULL */
>  		}
>  
> -		/* we have a specified --huge-dir option, only examine that dir */
> -		if (internal_conf->hugepage_dir != NULL &&
> -				strcmp(splitstr[MOUNTPT], internal_conf->hugepage_dir) != 0)
> -			continue;
> +		dir = splitstr[MOUNTPT];
> +
> +		/*
> +		 * If a --huge-dir option has been specified, only examine
> +		 * mounts that contain that directory, and make sure to return
> +		 * the directory, not the mount.
> +		 */
> +		if (internal_conf->hugepage_dir != NULL) {
> +			if (strncmp(internal_conf->hugepage_dir,
> +				splitstr[MOUNTPT],
> +				strlen(splitstr[MOUNTPT])) != 0)
> +				continue;
> +
> +			dir = internal_conf->hugepage_dir;
> +		}

Suppose there are /mnt/huge and /mnt/huge-2M mounted with -o pagesize=2M.
If --huge-dir=/mnt/huge-2M is specified, this code will select /mnt/huge.
The code would be shorter with `splitstr[MOUNTPT]` -> `dir`.