On Tue, 2018-06-26 at 11:00 -0600, Keith Busch wrote:
> The available_size attribute returns all the unused regions, but a
> namespace has to use contiguous free regions. This patch uses the
> attribute returning the largest capacity that can be created for
> determining if the namespace can be created.
>
> If this is used on a kernel that predates the new attribute, ndctl will
> fall back to the previous behavior using available_size. While that may
> still fail, it is more likely to succeed than returning a hard-coded
> value.
>
> Signed-off-by: Keith Busch <[email protected]>
> ---
> v1 -> v2:
>
> Appropriate subject-prefex for ndctl.
>
> Added the fallback to the previous behavior if the attribute is not
> found, and noted this behavior in the changelog.
>
> ndctl/lib/libndctl.c | 31 +++++++++++++++++++++++++++++++
> ndctl/lib/libndctl.sym | 1 +
> ndctl/libndctl.h | 2 ++
> ndctl/namespace.c | 2 +-
> 4 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
> index 47e005e..8ff1fa6 100644
> --- a/ndctl/lib/libndctl.c
> +++ b/ndctl/lib/libndctl.c
> @@ -2025,6 +2025,37 @@ NDCTL_EXPORT unsigned long long
> ndctl_region_get_available_size(
> return strtoull(buf, NULL, 0);
> }
>
> +NDCTL_EXPORT unsigned long long ndctl_region_get_max_available_extent(
> + struct ndctl_region *region)
> +{
> + unsigned int nstype = ndctl_region_get_nstype(region);
> + struct ndctl_ctx *ctx = ndctl_region_get_ctx(region);
> + char *path = region->region_buf;
> + int len = region->buf_len;
> + char buf[SYSFS_ATTR_SIZE];
> +
> + switch (nstype) {
> + case ND_DEVICE_NAMESPACE_PMEM:
> + case ND_DEVICE_NAMESPACE_BLK:
> + break;
> + default:
> + return 0;
> + }
> +
> + if (snprintf(path, len,
> + "%s/max_available_extent", region->region_path) >=
> len) {
> + err(ctx, "%s: buffer too small!\n",
> + ndctl_region_get_devname(region));
> + return ULLONG_MAX;
> + }
> +
> + /* fall back to legacy behavior if max extents is not exported
> */
> + if (sysfs_read_attr(ctx, path, buf) < 0)
> + return ndctl_region_get_available_size(region);
Instead of silently falling back to the legacy behavior, perhaps we should
print a dbg() warning here so that the user can be prompted to update their
kernel.
> +
> + return strtoull(buf, NULL, 0);
> +}
> +
> NDCTL_EXPORT unsigned int ndctl_region_get_range_index(struct
> ndctl_region *region)
> {
> return region->range_index;
> diff --git a/ndctl/lib/libndctl.sym b/ndctl/lib/libndctl.sym
> index c1228e5..22fd026 100644
> --- a/ndctl/lib/libndctl.sym
> +++ b/ndctl/lib/libndctl.sym
> @@ -123,6 +123,7 @@ global:
> ndctl_region_get_mappings;
> ndctl_region_get_size;
> ndctl_region_get_available_size;
> + ndctl_region_get_max_available_extent;
> ndctl_region_get_type;
> ndctl_region_get_namespace_seed;
> ndctl_region_get_btt_seed;
> diff --git a/ndctl/libndctl.h b/ndctl/libndctl.h
> index be997ac..624115d 100644
> --- a/ndctl/libndctl.h
> +++ b/ndctl/libndctl.h
> @@ -338,6 +338,8 @@ unsigned int ndctl_region_get_interleave_ways(struct
> ndctl_region *region);
> unsigned int ndctl_region_get_mappings(struct ndctl_region *region);
> unsigned long long ndctl_region_get_size(struct ndctl_region *region);
> unsigned long long ndctl_region_get_available_size(struct ndctl_region
> *region);
> +unsigned long long ndctl_region_get_max_available_extent(
> + struct ndctl_region *region);
> unsigned int ndctl_region_get_range_index(struct ndctl_region *region);
> unsigned int ndctl_region_get_type(struct ndctl_region *region);
> struct ndctl_namespace *ndctl_region_get_namespace_seed(
> diff --git a/ndctl/namespace.c b/ndctl/namespace.c
> index fe86d82..4a562a2 100644
> --- a/ndctl/namespace.c
> +++ b/ndctl/namespace.c
> @@ -764,7 +764,7 @@ static int namespace_create(struct ndctl_region
> *region)
> return -EAGAIN;
> }
>
> - available = ndctl_region_get_available_size(region);
> + available = ndctl_region_get_max_available_extent(region);
> if (!available || p.size > available) {
> debug("%s: insufficient capacity size: %llx avail:
> %llx\n",
> devname, p.size, available);
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