1 files changed, 95 insertions, 0 deletions

diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
new file mode 100644
index 000000000000..2663ed90fb03
--- /dev/null
+++ b/fs/quota/netlink.c
@@ -0,0 +1,95 @@
+
+#include <linux/cred.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/quotaops.h>
+#include <linux/sched.h>
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+/* Netlink family structure for quota */
+static struct genl_family quota_genl_family = {
+        .id = GENL_ID_GENERATE,
+        .hdrsize = 0,
+        .name = "VFS_DQUOT",
+        .version = 1,
+        .maxattr = QUOTA_NL_A_MAX,
+};
+
+/**
+ * quota_send_warning - Send warning to userspace about exceeded quota
+ * @type: The quota type: USRQQUOTA, GRPQUOTA,...
+ * @id: The user or group id of the quota that was exceeded
+ * @dev: The device on which the fs is mounted (sb->s_dev)
+ * @warntype: The type of the warning: QUOTA_NL_...
+ *
+ * This can be used by filesystems (including those which don't use
+ * dquot) to send a message to userspace relating to quota limits.
+ *
+ */
+
+void quota_send_warning(short type, unsigned int id, dev_t dev,
+                        const char warntype)
+{
+        static atomic_t seq;
+        struct sk_buff *skb;
+        void *msg_head;
+        int ret;
+        int msg_size = 4 * nla_total_size(sizeof(u32)) +
+                       2 * nla_total_size(sizeof(u64));
+
+        /* We have to allocate using GFP_NOFS as we are called from a
+         * filesystem performing write and thus further recursion into
+         * the fs to free some data could cause deadlocks. */
+        skb = genlmsg_new(msg_size, GFP_NOFS);
+        if (!skb) {
+                printk(KERN_ERR
+                  "VFS: Not enough memory to send quota warning.\n");
+                return;
+        }
+        msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
+                        &quota_genl_family, 0, QUOTA_NL_C_WARNING);
+        if (!msg_head) {
+                printk(KERN_ERR
+                  "VFS: Cannot store netlink header in quota warning.\n");
+                goto err_out;
+        }
+        ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
+        if (ret)
+                goto attr_err_out;
+        ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
+        if (ret)
+                goto attr_err_out;
+        ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
+        if (ret)
+                goto attr_err_out;
+        ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
+        if (ret)
+                goto attr_err_out;
+        ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
+        if (ret)
+                goto attr_err_out;
+        ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
+        if (ret)
+                goto attr_err_out;
+        genlmsg_end(skb, msg_head);
+
+        genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
+        return;
+attr_err_out:
+        printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
+err_out:
+        kfree_skb(skb);
+}
+EXPORT_SYMBOL(quota_send_warning);
+
+static int __init quota_init(void)
+{
+        if (genl_register_family(&quota_genl_family) != 0)
+                printk(KERN_ERR
+                       "VFS: Failed to create quota netlink interface.\n");
+        return 0;
+};
+
+module_init(quota_init);