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btrfs: sysfs: export supported checksums

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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: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2019-10-07 11:11:03 +02:00
parent 3831bf0094
commit f7cea56c0f
3 changed files with 29 additions and 0 deletions
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5
fs/btrfs/ctree.c
View File

@ -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);

2
fs/btrfs/ctree.h
View File

@ -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.

22
fs/btrfs/sysfs.c
View File

@ -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
};