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btrfs: publish fs label in sysfs 

This adds a writeable attribute which describes the label.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Jeff Mahoney 2013-11-01 13:07:06 -04:00 committed by Chris Mason
parent 29e5be240a
commit f8ba9c11f8
1 changed files with 44 additions and 0 deletions
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44
fs/btrfs/sysfs.c
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@ -355,6 +355,49 @@ static const struct attribute *allocation_attrs[] = {
NULL,
};
static ssize_t btrfs_label_show(struct kobject *kobj,
struct kobj_attribute *a, char *buf)
{
struct btrfs_fs_info *fs_info = to_fs_info(kobj);
return snprintf(buf, PAGE_SIZE, "%s\n", fs_info->super_copy->label);
}
static ssize_t btrfs_label_store(struct kobject *kobj,
struct kobj_attribute *a,
const char *buf, size_t len)
{
struct btrfs_fs_info *fs_info = to_fs_info(kobj);
struct btrfs_trans_handle *trans;
struct btrfs_root *root = fs_info->fs_root;
int ret;
if (len >= BTRFS_LABEL_SIZE) {
pr_err("btrfs: unable to set label with more than %d bytes\n",
BTRFS_LABEL_SIZE - 1);
return -EINVAL;
}
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans))
return PTR_ERR(trans);
spin_lock(&root->fs_info->super_lock);
strcpy(fs_info->super_copy->label, buf);
spin_unlock(&root->fs_info->super_lock);
ret = btrfs_commit_transaction(trans, root);
if (!ret)
return len;
return ret;
}
BTRFS_ATTR_RW(label, 0644, btrfs_label_show, btrfs_label_store);
static struct attribute *btrfs_attrs[] = {
BTRFS_ATTR_PTR(label),
NULL,
};
static void btrfs_release_super_kobj(struct kobject *kobj)
{
struct btrfs_fs_info *fs_info = to_fs_info(kobj);
@ -364,6 +407,7 @@ static void btrfs_release_super_kobj(struct kobject *kobj)
static struct kobj_type btrfs_ktype = {
.sysfs_ops = &kobj_sysfs_ops,
.release = btrfs_release_super_kobj,
.default_attrs = btrfs_attrs,
};
static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)