memcg has a significant number of files exposed to kernfs where their
value is either exposed directly or is "max" in the case of
PAGE_COUNTER_MAX.

This patch makes this generic by providing a single function to do this
work. In combination with the previous patch adding mem_cgroup_from_seq,
this makes all of the seq_show feeder functions significantly more
simple.

Signed-off-by: Chris Down <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
 mm/memcontrol.c | 64 +++++++++++++++----------------------------------
 1 file changed, 19 insertions(+), 45 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 98aad31f5226..81b6f752471a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5375,6 +5375,16 @@ static void mem_cgroup_bind(struct cgroup_subsys_state 
*root_css)
                root_mem_cgroup->use_hierarchy = false;
 }
 
+static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
+{
+       if (value == PAGE_COUNTER_MAX)
+               seq_puts(m, "max\n");
+       else
+               seq_printf(m, "%llu\n", (u64)value * PAGE_SIZE);
+
+       return 0;
+}
+
 static u64 memory_current_read(struct cgroup_subsys_state *css,
                               struct cftype *cft)
 {
@@ -5385,15 +5395,8 @@ static u64 memory_current_read(struct 
cgroup_subsys_state *css,
 
 static int memory_min_show(struct seq_file *m, void *v)
 {
-       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-       unsigned long min = READ_ONCE(memcg->memory.min);
-
-       if (min == PAGE_COUNTER_MAX)
-               seq_puts(m, "max\n");
-       else
-               seq_printf(m, "%llu\n", (u64)min * PAGE_SIZE);
-
-       return 0;
+       return seq_puts_memcg_tunable(m,
+               READ_ONCE(mem_cgroup_from_seq(m)->memory.min));
 }
 
 static ssize_t memory_min_write(struct kernfs_open_file *of,
@@ -5415,15 +5418,8 @@ static ssize_t memory_min_write(struct kernfs_open_file 
*of,
 
 static int memory_low_show(struct seq_file *m, void *v)
 {
-       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-       unsigned long low = READ_ONCE(memcg->memory.low);
-
-       if (low == PAGE_COUNTER_MAX)
-               seq_puts(m, "max\n");
-       else
-               seq_printf(m, "%llu\n", (u64)low * PAGE_SIZE);
-
-       return 0;
+       return seq_puts_memcg_tunable(m,
+               READ_ONCE(mem_cgroup_from_seq(m)->memory.low));
 }
 
 static ssize_t memory_low_write(struct kernfs_open_file *of,
@@ -5445,15 +5441,7 @@ static ssize_t memory_low_write(struct kernfs_open_file 
*of,
 
 static int memory_high_show(struct seq_file *m, void *v)
 {
-       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-       unsigned long high = READ_ONCE(memcg->high);
-
-       if (high == PAGE_COUNTER_MAX)
-               seq_puts(m, "max\n");
-       else
-               seq_printf(m, "%llu\n", (u64)high * PAGE_SIZE);
-
-       return 0;
+       return seq_puts_memcg_tunable(m, 
READ_ONCE(mem_cgroup_from_seq(m)->high));
 }
 
 static ssize_t memory_high_write(struct kernfs_open_file *of,
@@ -5482,15 +5470,8 @@ static ssize_t memory_high_write(struct kernfs_open_file 
*of,
 
 static int memory_max_show(struct seq_file *m, void *v)
 {
-       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-       unsigned long max = READ_ONCE(memcg->memory.max);
-
-       if (max == PAGE_COUNTER_MAX)
-               seq_puts(m, "max\n");
-       else
-               seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE);
-
-       return 0;
+       return seq_puts_memcg_tunable(m,
+               READ_ONCE(mem_cgroup_from_seq(m)->memory.max));
 }
 
 static ssize_t memory_max_write(struct kernfs_open_file *of,
@@ -6622,15 +6603,8 @@ static u64 swap_current_read(struct cgroup_subsys_state 
*css,
 
 static int swap_max_show(struct seq_file *m, void *v)
 {
-       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
-       unsigned long max = READ_ONCE(memcg->swap.max);
-
-       if (max == PAGE_COUNTER_MAX)
-               seq_puts(m, "max\n");
-       else
-               seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE);
-
-       return 0;
+       return seq_puts_memcg_tunable(m,
+               READ_ONCE(mem_cgroup_from_seq(m)->swap.max));
 }
 
 static ssize_t swap_max_write(struct kernfs_open_file *of,
-- 
2.20.1

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