From 2723480a0f8fe6c045d23715eaa28f208644f42a Mon Sep 17 00:00:00 2001 From: Sargun Dhillon Date: Thu, 11 May 2017 21:18:03 +0000 Subject: [PATCH] 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: Sargun Dhillon Reviewed-by: David Sterba [ minor changelog edits ] Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 1f157fba8940..c2d5f3580b4c 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, };