VFS: Export dquot_send_warning
[linux-2.6.git] / fs / quota / quota.c
index 95c5b42..ee91e27 100644 (file)
@@ -18,6 +18,8 @@
 #include <linux/capability.h>
 #include <linux/quotaops.h>
 #include <linux/types.h>
+#include <net/netlink.h>
+#include <net/genetlink.h>
 
 /* Check validity of generic quotactl commands */
 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd,
@@ -525,3 +527,94 @@ asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
        return ret;
 }
 #endif
+
+
+#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
+
+/* 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);
+#endif
+