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- #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 <linux/slab.h>
- #include <net/netlink.h>
- #include <net/genetlink.h>
- static const struct genl_multicast_group quota_mcgrps[] = {
- { .name = "events", },
- };
- /* Netlink family structure for quota */
- static struct genl_family quota_genl_family = {
- /*
- * Needed due to multicast group ID abuse - old code assumed
- * the family ID was also a valid multicast group ID (which
- * isn't true) and userspace might thus rely on it. Assign a
- * static ID for this group to make dealing with that easier.
- */
- .id = GENL_ID_VFS_DQUOT,
- .hdrsize = 0,
- .name = "VFS_DQUOT",
- .version = 1,
- .maxattr = QUOTA_NL_A_MAX,
- .mcgrps = quota_mcgrps,
- .n_mcgrps = ARRAY_SIZE(quota_mcgrps),
- };
- /**
- * quota_send_warning - Send warning to userspace about exceeded quota
- * @qid: The kernel internal quota identifier.
- * @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(struct kqid qid, 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),
- "a_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, qid.type);
- if (ret)
- goto attr_err_out;
- ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID,
- from_kqid_munged(&init_user_ns, qid));
- 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,
- from_kuid_munged(&init_user_ns, current_uid()));
- if (ret)
- goto attr_err_out;
- genlmsg_end(skb, msg_head);
- genlmsg_multicast("a_genl_family, skb, 0, 0, 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("a_genl_family) != 0)
- printk(KERN_ERR
- "VFS: Failed to create quota netlink interface.\n");
- return 0;
- };
- module_init(quota_init);
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