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Commit 2723480a authored by Sargun Dhillon's avatar Sargun Dhillon Committed by David Sterba
Browse files

btrfs: Add quota_override knob into sysfs 



This patch adds the read-write attribute quota_override into sysfs.
Any process which has CAP_SYS_RESOURCE can set this flag to on, and
once it is set to true, processes with CAP_SYS_RESOURCE can exceed
the quota.

Signed-off-by: default avatarSargun Dhillon <sargun@sargun.me>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ minor changelog edits ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f29efe29

fs/btrfs/sysfs.c

+41 −0
Original line number Diff line number Diff line
@@ -447,11 +447,52 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj, 


BTRFS_ATTR(clone_alignment, btrfs_clone_alignment_show);



static ssize_t quota_override_show(struct kobject *kobj,

				   struct kobj_attribute *a, char *buf)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);

	int quota_override;



	quota_override = test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);

	return snprintf(buf, PAGE_SIZE, "%d\n", quota_override);

}



static ssize_t quota_override_store(struct kobject *kobj,

				    struct kobj_attribute *a,

				    const char *buf, size_t len)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);

	unsigned long knob;

	int err;



	if (!fs_info)

		return -EPERM;



	if (!capable(CAP_SYS_RESOURCE))

		return -EPERM;



	err = kstrtoul(buf, 10, &knob);

	if (err)

		return err;

	if (knob > 1)

		return -EINVAL;



	if (knob)

		set_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);

	else

		clear_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);



	return len;

}



BTRFS_ATTR_RW(quota_override, quota_override_show, quota_override_store);



static const struct attribute *btrfs_attrs[] = {

	BTRFS_ATTR_PTR(label),

	BTRFS_ATTR_PTR(nodesize),

	BTRFS_ATTR_PTR(sectorsize),

	BTRFS_ATTR_PTR(clone_alignment),

	BTRFS_ATTR_PTR(quota_override),

	NULL,

};