@@ -111,6 +111,8 @@
 #include <linux/poll.h>
 #include <linux/tcp.h>
 #include <linux/init.h>
+#include <linux/blkdev.h>

 #include <asm/uaccess.h>
 #include <asm/system.h>

@@ -195,6 +197,78 @@ __u32 sysctl_rmem_default = SK_RMEM_MAX;
 /* Maximal space eaten by iovec or ancilliary data plus some space */
 int sysctl_optmem_max = sizeof(unsigned long)*(2*UIO_MAXIOV + 512);

+static DEFINE_SPINLOCK(memalloc_lock);
+static int memalloc_socks;
+static unsigned long memalloc_reserve;
+
+atomic_t memalloc_skbs_used;
+EXPORT_SYMBOL_GPL(memalloc_skbs_used);
+
+/**
+ *        sk_adjust_memalloc - adjust the global memalloc reserve
+ *        @nr_socks: number of new %SOCK_MEMALLOC sockets
+ *
+ *        This function adjusts the memalloc reserve based on system demand.
+ *        For each %SOCK_MEMALLOC socket 2 * %MAX_PHYS_SEGMENTS pages are
+ *        reserved for outbound traffic (assumption: each %SOCK_MEMALLOC
+ *        socket will have a %request_queue associated).
+ *
+ *        Pages for inbound traffic are already reserved.
+ *
+ *        2 * %MAX_PHYS_SEGMENTS - the request queue can hold up to 150%,
+ *                the remaining 50% goes to being sure we can write packets
+ *                for the outgoing pages.
+ */
+static DEFINE_SPINLOCK(memalloc_lock);
+static int memalloc_socks;
+
+atomic_t memalloc_skbs_used;
+EXPORT_SYMBOL_GPL(memalloc_skbs_used);
+
+int sk_adjust_memalloc(int nr_socks)
+{
+	unsigned long flags;
+	unsigned int reserve;
+	int err;
+
+	spin_lock_irqsave(&memalloc_lock, flags);
+
+	memalloc_socks += nr_socks;
+	BUG_ON(memalloc_socks < 0);
+
+	reserve = nr_socks * 2 * MAX_PHYS_SEGMENTS;	/* outbound */
+
+	err = adjust_memalloc_reserve(reserve);
+	spin_unlock_irqrestore(&memalloc_lock, flags);
+	if (err) {
+		printk(KERN_WARNING
+			"Unable to adjust RX reserve by %lu, error: %d\n",
+			reserve, err);
+	}
+	return err;
+}
+EXPORT_SYMBOL_GPL(sk_adjust_memalloc);