Commit f7cea56c authored by David Sterba's avatar David Sterba
Browse files

btrfs: sysfs: export supported checksums 



Export supported checksum algorithms via sysfs in the list of static
features:

  /sys/fs/btrfs/features/supported_checksums

Space spearated list of checksum algorithm names.

Co-developed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 3831bf00

fs/btrfs/ctree.c

+5 −0
Original line number Diff line number Diff line
@@ -53,6 +53,11 @@ const char *btrfs_super_csum_name(u16 csum_type) 
	return btrfs_csums[csum_type].name;

}



size_t __const btrfs_get_num_csums(void)

{

	return ARRAY_SIZE(btrfs_csums);

}



struct btrfs_path *btrfs_alloc_path(void)

{

	return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);

fs/btrfs/ctree.h

+2 −0
Original line number Diff line number Diff line
@@ -2163,6 +2163,8 @@ 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 __const btrfs_get_num_csums(void);





/*

 * The leaf data grows from end-to-front in the node.

fs/btrfs/sysfs.c

+22 −0
Original line number Diff line number Diff line
@@ -295,8 +295,30 @@ static ssize_t rmdir_subvol_show(struct kobject *kobj, 
}

BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);



static ssize_t 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_ATTR(static_feature, supported_checksums, supported_checksums_show);



static struct attribute *btrfs_supported_static_feature_attrs[] = {

	BTRFS_ATTR_PTR(static_feature, rmdir_subvol),

	BTRFS_ATTR_PTR(static_feature, supported_checksums),

	NULL

};