| Message ID | 20170421231304.GA3787@ircssh-2.c.rugged-nimbus-611.internal (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Apr 21, 2017 at 11:13:06PM +0000, Sargun Dhillon wrote: > 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. So we've moved to the hardest part, where to put the sysfs file and how to name it. My first though was against putting it right under the filesystem UUID and rather introduce a directory with all tunables, but we already have a read-write label there. Ok then. The valid values are 0 and 1. And no locking is needed as fs_info::flags are updated atomically (once patch 1 is updated). -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 1f157fb..c62acca 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -447,11 +447,47 @@ 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); + + return snprintf(buf, PAGE_SIZE, "%d\n", fs_info->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; + + fs_info->quota_override = !!knob; + + 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, };
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: Sargun Dhillon <sargun@sargun.me> --- fs/btrfs/sysfs.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)