cgroup: replace cftype->read_seq_string() with cftype->seq_show()

In preparation of conversion to kernfs, cgroup file handling is
updated so that it can be easily mapped to kernfs.  This patch
replaces cftype->read_seq_string() with cftype->seq_show() which is
not limited to single_open() operation and will map directcly to
kernfs seq_file interface.

The conversions are mechanical.  As ->seq_show() doesn't have @css and
@cft, the functions which make use of them are converted to use
seq_css() and seq_cft() respectively.  In several occassions, e.f. if
it has seq_string in its name, the function name is updated to fit the
new method better.

This patch does not introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Neil Horman <nhorman@tuxdriver.com>

1 files changed, 16 insertions, 18 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 036c05d8e572..c45e63328a0a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2212,10 +2212,9 @@ static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
 	return 0;
 }
 
-static int cgroup_release_agent_show(struct cgroup_subsys_state *css,
-				     struct cftype *cft, struct seq_file *seq)
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
 {
-	struct cgroup *cgrp = css->cgroup;
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
 
 	if (!cgroup_lock_live_group(cgrp))
 		return -ENODEV;
@@ -2225,10 +2224,11 @@ static int cgroup_release_agent_show(struct cgroup_subsys_state *css,
 	return 0;
 }
 
-static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css,
-				     struct cftype *cft, struct seq_file *seq)
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
 {
-	seq_printf(seq, "%d\n", cgroup_sane_behavior(css->cgroup));
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+	seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
 	return 0;
 }
 
@@ -2291,8 +2291,8 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg)
 	struct cftype *cft = seq_cft(m);
 	struct cgroup_subsys_state *css = seq_css(m);
 
-	if (cft->read_seq_string)
-		return cft->read_seq_string(css, cft, m);
+	if (cft->seq_show)
+		return cft->seq_show(m, arg);
 
 	if (cft->read_u64)
 		seq_printf(m, "%llu\n", cft->read_u64(css, cft));
@@ -2559,7 +2559,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
 	if (cft->mode)
 		return cft->mode;
 
-	if (cft->read_u64 || cft->read_s64 || cft->read_seq_string)
+	if (cft->read_u64 || cft->read_s64 || cft->seq_show)
 		mode |= S_IRUGO;
 
 	if (cft->write_u64 || cft->write_s64 || cft->write_string ||
@@ -3874,7 +3874,7 @@ static struct cftype cgroup_base_files[] = {
 	{
 		.name = "cgroup.sane_behavior",
 		.flags = CFTYPE_ONLY_ON_ROOT,
-		.read_seq_string = cgroup_sane_behavior_show,
+		.seq_show = cgroup_sane_behavior_show,
 	},
 
 	/*
@@ -3899,7 +3899,7 @@ static struct cftype cgroup_base_files[] = {
 	{
 		.name = "release_agent",
 		.flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
-		.read_seq_string = cgroup_release_agent_show,
+		.seq_show = cgroup_release_agent_show,
 		.write_string = cgroup_release_agent_write,
 		.max_write_len = PATH_MAX,
 	},
@@ -5274,9 +5274,7 @@ static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
 	return count;
 }
 
-static int current_css_set_cg_links_read(struct cgroup_subsys_state *css,
-					 struct cftype *cft,
-					 struct seq_file *seq)
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
 {
 	struct cgrp_cset_link *link;
 	struct css_set *cset;
@@ -5301,9 +5299,9 @@ static int current_css_set_cg_links_read(struct cgroup_subsys_state *css,
 }
 
 #define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct cgroup_subsys_state *css,
-				 struct cftype *cft, struct seq_file *seq)
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
 {
+	struct cgroup_subsys_state *css = seq_css(seq);
 	struct cgrp_cset_link *link;
 
 	read_lock(&css_set_lock);
@@ -5349,12 +5347,12 @@ static struct cftype debug_files[] =  {
 
 	{
 		.name = "current_css_set_cg_links",
-		.read_seq_string = current_css_set_cg_links_read,
+		.seq_show = current_css_set_cg_links_read,
 	},
 
 	{
 		.name = "cgroup_css_links",
-		.read_seq_string = cgroup_css_links_read,
+		.seq_show = cgroup_css_links_read,
 	},
 
 	{