On 7.10.19 г. 12:11 ч., Johannes Thumshirn wrote:
> From: David Sterba <dste...@suse.com>
>
> Export supported checksum algorithms via sysfs.
>
> Co-developed-by: David Sterba <dste...@suse.com>
> Signed-off-by: Johannes Thumshirn <jthumsh...@suse.de>
> ---
> fs/btrfs/ctree.c | 5 +++++
> fs/btrfs/ctree.h | 2 ++
> fs/btrfs/sysfs.c | 33 +++++++++++++++++++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index b66509ee62eb..5debd74dc61c 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -53,6 +53,11 @@ const char *btrfs_super_csum_name(u16 csum_type)
> return btrfs_csums[csum_type].name;
> }
>
> +size_t btrfs_get_num_csums(void)
> +{
> + return ARRAY_SIZE(btrfs_csums);
> +}
nit: This function is used only once and the ARRAY_SIZE() macro is
descriptive enough, why not just remove it and opencoude the call to
array_size
> +
> struct btrfs_path *btrfs_alloc_path(void)
> {
> return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index d17e79a40930..0180554f6970 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -2165,6 +2165,8 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation,
> struct btrfs_super_block,
>
> int btrfs_super_csum_size(const struct btrfs_super_block *s);
> const char *btrfs_super_csum_name(u16 csum_type);
> +size_t btrfs_get_num_csums(void);
> +
>
> /*
> * The leaf data grows from end-to-front in the node.
> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
> index f6d3c80f2e28..aeebbdfe1a98 100644
> --- a/fs/btrfs/sysfs.c
> +++ b/fs/btrfs/sysfs.c
> @@ -246,6 +246,28 @@ static umode_t btrfs_feature_visible(struct kobject
> *kobj,
> return mode;
> }
>
> +static ssize_t btrfs_supported_checksums_show(struct kobject *kobj,
> + struct kobj_attribute *a,
> + char *buf)
> +{
> + ssize_t ret = 0;
> + int i;
> +
> + for (i = 0; i < btrfs_get_num_csums(); i++) {
> + /*
> + * This "trick" only works as long as 'enum btrfs_csum_type' has
> + * no holes in it
> + */
> + ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
> + (i == 0 ? "" : ", "),
> + btrfs_super_csum_name(i));
> +
> + }
> +
> + ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
> + return ret;
> +}
> +
> BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
> BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
> BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
> @@ -259,6 +281,14 @@ BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
> BTRFS_FEAT_ATTR_INCOMPAT(metadata_uuid, METADATA_UUID);
> BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
>
> +static struct btrfs_feature_attr btrfs_attr_features_checksums_name = {
> + .kobj_attr = __INIT_KOBJ_ATTR(supported_checksums, S_IRUGO,
> + btrfs_supported_checksums_show,
> + NULL),
> + .feature_set = FEAT_INCOMPAT,
> + .feature_bit = 0,
> +};
> +
> static struct attribute *btrfs_supported_feature_attrs[] = {
> BTRFS_FEAT_ATTR_PTR(mixed_backref),
> BTRFS_FEAT_ATTR_PTR(default_subvol),
> @@ -272,6 +302,9 @@ static struct attribute *btrfs_supported_feature_attrs[]
> = {
> BTRFS_FEAT_ATTR_PTR(no_holes),
> BTRFS_FEAT_ATTR_PTR(metadata_uuid),
> BTRFS_FEAT_ATTR_PTR(free_space_tree),
> +
> + &btrfs_attr_features_checksums_name.kobj_attr.attr,
> +
> NULL
> };
>
>
