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authorSteven Whitehouse <swhiteho@redhat.com>2009-09-28 12:35:17 +0100
committerSteven Whitehouse <swhiteho@redhat.com>2009-12-03 11:53:02 +0000
commit86e931a35e93d94e6e91b57cc76456e16d188ea9 (patch)
tree55078897d1c3dfa43fed6458a7721af17362b4a3 /fs/quota/quota.c
parente285c100362762f7440643be637dd332460fdc75 (diff)
VFS: Export dquot_send_warning
Sending a message to userspace in a generic format to warn of events (e.g. quota exceeded) in the quota subsystem is a generically useful feature. This patch makes some minor changes to the send_message function from dquot.c renaming it quota_send_message, moving it to quota.c and exporting it for use by filesystems which do not use the dquot code. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/quota/quota.c')
-rw-r--r--fs/quota/quota.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 95c5b42384b..ee91e275695 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -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
+