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 <sar...@sargun.me>
---
fs/btrfs/sysfs.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 1f157fb..c2d5f35 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -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,
};
--
2.9.3
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