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 <linux/slab.h> 9 #include <net/netlink.h> 10 #include <net/genetlink.h> 11 12 /* Netlink family structure for quota */ 13 static struct genl_family quota_genl_family = { 14 .id = GENL_ID_GENERATE, 15 .hdrsize = 0, 16 .name = "VFS_DQUOT", 17 .version = 1, 18 .maxattr = QUOTA_NL_A_MAX, 19 }; 20 21 /** 22 * quota_send_warning - Send warning to userspace about exceeded quota 23 * @type: The quota type: USRQQUOTA, GRPQUOTA,... 24 * @id: The user or group id of the quota that was exceeded 25 * @dev: The device on which the fs is mounted (sb->s_dev) 26 * @warntype: The type of the warning: QUOTA_NL_... 27 * 28 * This can be used by filesystems (including those which don't use 29 * dquot) to send a message to userspace relating to quota limits. 30 * 31 */ 32 33 void quota_send_warning(short type, unsigned int id, dev_t dev, 34 const char warntype) 35 { 36 static atomic_t seq; 37 struct sk_buff *skb; 38 void *msg_head; 39 int ret; 40 int msg_size = 4 * nla_total_size(sizeof(u32)) + 41 2 * nla_total_size(sizeof(u64)); 42 43 /* We have to allocate using GFP_NOFS as we are called from a 44 * filesystem performing write and thus further recursion into 45 * the fs to free some data could cause deadlocks. */ 46 skb = genlmsg_new(msg_size, GFP_NOFS); 47 if (!skb) { 48 printk(KERN_ERR 49 "VFS: Not enough memory to send quota warning.\n"); 50 return; 51 } 52 msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq), 53 "a_genl_family, 0, QUOTA_NL_C_WARNING); 54 if (!msg_head) { 55 printk(KERN_ERR 56 "VFS: Cannot store netlink header in quota warning.\n"); 57 goto err_out; 58 } 59 ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type); 60 if (ret) 61 goto attr_err_out; 62 ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id); 63 if (ret) 64 goto attr_err_out; 65 ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype); 66 if (ret) 67 goto attr_err_out; 68 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev)); 69 if (ret) 70 goto attr_err_out; 71 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev)); 72 if (ret) 73 goto attr_err_out; 74 ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid()); 75 if (ret) 76 goto attr_err_out; 77 genlmsg_end(skb, msg_head); 78 79 genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS); 80 return; 81 attr_err_out: 82 printk(KERN_ERR "VFS: Not enough space to compose quota message!\n"); 83 err_out: 84 kfree_skb(skb); 85 } 86 EXPORT_SYMBOL(quota_send_warning); 87 88 static int __init quota_init(void) 89 { 90 if (genl_register_family("a_genl_family) != 0) 91 printk(KERN_ERR 92 "VFS: Failed to create quota netlink interface.\n"); 93 return 0; 94 }; 95 96 module_init(quota_init); 97