fs/quota/netlink.c

   1
   2 #include <linux/cred.h>
   3 #include <linux/init.h>
   4 #include <linux/module.h>
   5 #include <linux/kernel.h>
   6 #include <linux/quotaops.h>
   7 #include <linux/sched.h>
   8 #include <net/netlink.h>
   9 #include <net/genetlink.h>
  10
  11 /* Netlink family structure for quota */
  12 static struct genl_family quota_genl_family = {
  13         .id = GENL_ID_GENERATE,
  14         .hdrsize = 0,
  15         .name = "VFS_DQUOT",
  16         .version = 1,
  17         .maxattr = QUOTA_NL_A_MAX,
  18 };
  19
  20 /**
  21  * quota_send_warning - Send warning to userspace about exceeded quota
  22  * @type: The quota type: USRQQUOTA, GRPQUOTA,...
  23  * @id: The user or group id of the quota that was exceeded
  24  * @dev: The device on which the fs is mounted (sb->s_dev)
  25  * @warntype: The type of the warning: QUOTA_NL_...
  26  *
  27  * This can be used by filesystems (including those which don't use
  28  * dquot) to send a message to userspace relating to quota limits.
  29  *
  30  */
  31
  32 void quota_send_warning(short type, unsigned int id, dev_t dev,
  33                         const char warntype)
  34 {
  35         static atomic_t seq;
  36         struct sk_buff *skb;
  37         void *msg_head;
  38         int ret;
  39         int msg_size = 4 * nla_total_size(sizeof(u32)) +
  40                        2 * nla_total_size(sizeof(u64));
  41
  42         /* We have to allocate using GFP_NOFS as we are called from a
  43          * filesystem performing write and thus further recursion into
  44          * the fs to free some data could cause deadlocks. */
  45         skb = genlmsg_new(msg_size, GFP_NOFS);
  46         if (!skb) {
  47                 printk(KERN_ERR
  48                   "VFS: Not enough memory to send quota warning.\n");
  49                 return;
  50         }
  51         msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
  52                         &quota_genl_family, 0, QUOTA_NL_C_WARNING);
  53         if (!msg_head) {
  54                 printk(KERN_ERR
  55                   "VFS: Cannot store netlink header in quota warning.\n");
  56                 goto err_out;
  57         }
  58         ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
  59         if (ret)
  60                 goto attr_err_out;
  61         ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
  62         if (ret)
  63                 goto attr_err_out;
  64         ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
  65         if (ret)
  66                 goto attr_err_out;
  67         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
  68         if (ret)
  69                 goto attr_err_out;
  70         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
  71         if (ret)
  72                 goto attr_err_out;
  73         ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
  74         if (ret)
  75                 goto attr_err_out;
  76         genlmsg_end(skb, msg_head);
  77
  78         genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
  79         return;
  80 attr_err_out:
  81         printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
  82 err_out:
  83         kfree_skb(skb);
  84 }
  85 EXPORT_SYMBOL(quota_send_warning);
  86
  87 static int __init quota_init(void)
  88 {
  89         if (genl_register_family(&quota_genl_family) != 0)
  90                 printk(KERN_ERR
  91                        "VFS: Failed to create quota netlink interface.\n");
  92         return 0;
  93 };
  94
  95 module_init(quota_init);