[PATCH 2/4] swapcgroup: add member to swap_info_struct for cgroup

[Daisuke Nishimura <nishimura-YQH0OdQVrdy45+QrQBaojngSJqDPrsil@public.gmane.org>]

This patch add a member to swap_info_struct for cgroup.

This member, array of pointers to mem_cgroup, is used to
remember to which cgroup each swap entries are charged.

The memory for this array of pointers is allocated on swapon,
and freed on swapoff.


Signed-off-by: Daisuke Nishimura <nishimura-YQH0OdQVrdy45+QrQBaojngSJqDPrsil@public.gmane.org>

---
 include/linux/swap.h |    3 +++
 mm/swapfile.c        |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index de40f16..67de27b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -141,6 +141,9 @@ struct swap_info_struct {
 	struct swap_extent *curr_swap_extent;
 	unsigned old_block_size;
 	unsigned short * swap_map;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	struct mem_cgroup **memcg;
+#endif
 	unsigned int lowest_bit;
 	unsigned int highest_bit;
 	unsigned int cluster_next;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index d3caf3a..232bf20 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1207,6 +1207,9 @@ asmlinkage long sys_swapoff(const char __user * specialfile)
 {
 	struct swap_info_struct * p = NULL;
 	unsigned short *swap_map;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	struct mem_cgroup **memcg;
+#endif
 	struct file *swap_file, *victim;
 	struct address_space *mapping;
 	struct inode *inode;
@@ -1309,10 +1312,17 @@ asmlinkage long sys_swapoff(const char __user * specialfile)
 	p->max = 0;
 	swap_map = p->swap_map;
 	p->swap_map = NULL;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	memcg = p->memcg;
+	p->memcg = NULL;
+#endif
 	p->flags = 0;
 	spin_unlock(&swap_lock);
 	mutex_unlock(&swapon_mutex);
 	vfree(swap_map);
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	vfree(memcg);
+#endif
 	inode = mapping->host;
 	if (S_ISBLK(inode->i_mode)) {
 		struct block_device *bdev = I_BDEV(inode);
@@ -1456,6 +1466,9 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 	unsigned long maxpages = 1;
 	int swapfilesize;
 	unsigned short *swap_map;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	struct mem_cgroup **memcg;
+#endif
 	struct page *page = NULL;
 	struct inode *inode = NULL;
 	int did_down = 0;
@@ -1479,6 +1492,9 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 	p->swap_file = NULL;
 	p->old_block_size = 0;
 	p->swap_map = NULL;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	p->memcg = NULL;
+#endif
 	p->lowest_bit = 0;
 	p->highest_bit = 0;
 	p->cluster_nr = 0;
@@ -1651,6 +1667,15 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
 				1 /* header page */;
 		if (error)
 			goto bad_swap;
+
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+		p->memcg = vmalloc(maxpages * sizeof(struct mem_cgroup *));
+		if (!p->memcg) {
+			error = -ENOMEM;
+			goto bad_swap;
+		}
+		memset(p->memcg, 0, maxpages * sizeof(struct mem_cgroup *));
+#endif
 	}
 
 	if (nr_good_pages) {
@@ -1710,11 +1735,18 @@ bad_swap_2:
 	swap_map = p->swap_map;
 	p->swap_file = NULL;
 	p->swap_map = NULL;
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	memcg = p->memcg;
+	p->memcg = NULL;
+#endif
 	p->flags = 0;
 	if (!(swap_flags & SWAP_FLAG_PREFER))
 		++least_priority;
 	spin_unlock(&swap_lock);
 	vfree(swap_map);
+#ifdef CONFIG_CGROUP_SWAP_RES_CTLR
+	vfree(memcg);
+#endif
 	if (swap_file)
 		filp_close(swap_file, NULL);
 out: