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From: Sargun Dhillon <sargun@sargun.me>
To: linux-btrfs@vger.kernel.org
Cc: dsterba@suse.cz, quwenruo@cn.fujitsu.com
Subject: [PATCH v2 2/2] btrfs: Add quota_override knob into sysfs
Date: Thu, 11 May 2017 21:18:03 +0000	[thread overview]
Message-ID: <20170511211801.GA8422@ircssh-2.c.rugged-nimbus-611.internal> (raw)
In-Reply-To: <20170511211658.GA8401@ircssh-2.c.rugged-nimbus-611.internal>

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 | 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


  parent reply	other threads:[~2017-05-11 21:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-11 21:17 [PATCH v2 0/2] btrfs: allow mechanism to override quota Sargun Dhillon
2017-05-11 21:17 ` [PATCH v2 1/2] btrfs: add quota override flag to enable quota override for sys_resource Sargun Dhillon
2017-05-11 21:18 ` Sargun Dhillon [this message]
2017-05-12 14:48 ` [PATCH v2 0/2] btrfs: allow mechanism to override quota David Sterba
2017-05-19  8:39   ` Sargun Dhillon
2017-05-19 13:26     ` David Sterba

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