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From:   Paolo Valente <paolo.valente@linaro.org>
To:     Jens Axboe <axboe@kernel.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Angelo Ruocco <angeloruocco90@gmail.com>,
        Dennis Zhou <dennis@kernel.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Liu Bo <bo.liu@linux.alibaba.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Johannes Weiner <hannes@cmpxchg.org>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        ulf.hansson@linaro.org, linus.walleij@linaro.org,
        broonie@kernel.org, bfq-iosched@googlegroups.com,
        oleksandr@natalenko.name, cgroups@vger.kernel.org,
        linux-doc@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Paolo Valente <paolo.valente@linaro.org>
Subject: [PATCH 03/12] block, cgroup: pass cftype to functions that need to use it
Date:   Mon, 12 Nov 2018 10:56:23 +0100
Message-Id: <20181112095632.69114-4-paolo.valente@linaro.org>
In-Reply-To: <20181112095632.69114-1-paolo.valente@linaro.org>
References: <20181112095632.69114-1-paolo.valente@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Some seq_show functions need to access the cftype they belong to, for
retrieving the data to show. These functions get their cftype by using
the seq_cft accessor for the seq_file. This solution is no longer
viable in case a seq_file is shared among more than one cftype,
because the accessor always returns (only) the first of the cftypes
sharing the seq_file.

This commit enables these seq_show functions to be passed their
cftype, by replacing their prototype with that of the newly defined
seq_show_cft hook, and by invoking these functions through this new
hook.

Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-cgroup.c         | 54 +++++++++++++++++++++++---------------------
 block/blk-cgroup.c         | 22 +++++++++++-------
 block/blk-throttle.c       |  8 +++----
 block/cfq-iosched.c        | 56 ++++++++++++++++++++++++----------------------
 include/linux/blk-cgroup.h | 10 +++++----
 5 files changed, 81 insertions(+), 69 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index d9a7916ff0ab..50b2d7ba6b9d 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -918,17 +918,17 @@ static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
 }
 
 #ifdef CONFIG_DEBUG_BLK_CGROUP
-static int bfqg_print_stat(struct seq_file *sf, void *v)
+static int bfqg_print_stat(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
+			  &blkcg_policy_bfq, cft->private, false);
 	return 0;
 }
 
-static int bfqg_print_rwstat(struct seq_file *sf, void *v)
+static int bfqg_print_rwstat(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
-			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
+			  &blkcg_policy_bfq, cft->private, true);
 	return 0;
 }
 
@@ -949,19 +949,21 @@ static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
 	return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 
-static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
+static int bfqg_print_stat_recursive(struct seq_file *sf, struct cftype *cft,
+				     void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
-			  seq_cft(sf)->private, false);
+			  cft->private, false);
 	return 0;
 }
 
-static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
+static int bfqg_print_rwstat_recursive(struct seq_file *sf, struct cftype *cft,
+				       void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
-			  seq_cft(sf)->private, true);
+			  cft->private, true);
 	return 0;
 }
 
@@ -1063,18 +1065,18 @@ struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.io_service_bytes",
 		.private = (unsigned long)&blkcg_policy_bfq,
-		.seq_show = blkg_print_stat_bytes,
+		.seq_show_cft = blkg_print_stat_bytes,
 	},
 	{
 		.name = "bfq.io_serviced",
 		.private = (unsigned long)&blkcg_policy_bfq,
-		.seq_show = blkg_print_stat_ios,
+		.seq_show_cft = blkg_print_stat_ios,
 	},
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	{
 		.name = "bfq.time",
 		.private = offsetof(struct bfq_group, stats.time),
-		.seq_show = bfqg_print_stat,
+		.seq_show_cft = bfqg_print_stat,
 	},
 	{
 		.name = "bfq.sectors",
@@ -1083,22 +1085,22 @@ struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.io_service_time",
 		.private = offsetof(struct bfq_group, stats.service_time),
-		.seq_show = bfqg_print_rwstat,
+		.seq_show_cft = bfqg_print_rwstat,
 	},
 	{
 		.name = "bfq.io_wait_time",
 		.private = offsetof(struct bfq_group, stats.wait_time),
-		.seq_show = bfqg_print_rwstat,
+		.seq_show_cft = bfqg_print_rwstat,
 	},
 	{
 		.name = "bfq.io_merged",
 		.private = offsetof(struct bfq_group, stats.merged),
-		.seq_show = bfqg_print_rwstat,
+		.seq_show_cft = bfqg_print_rwstat,
 	},
 	{
 		.name = "bfq.io_queued",
 		.private = offsetof(struct bfq_group, stats.queued),
-		.seq_show = bfqg_print_rwstat,
+		.seq_show_cft = bfqg_print_rwstat,
 	},
 #endif /* CONFIG_DEBUG_BLK_CGROUP */
 
@@ -1106,18 +1108,18 @@ struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.io_service_bytes_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
-		.seq_show = blkg_print_stat_bytes_recursive,
+		.seq_show_cft = blkg_print_stat_bytes_recursive,
 	},
 	{
 		.name = "bfq.io_serviced_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
-		.seq_show = blkg_print_stat_ios_recursive,
+		.seq_show_cft = blkg_print_stat_ios_recursive,
 	},
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	{
 		.name = "bfq.time_recursive",
 		.private = offsetof(struct bfq_group, stats.time),
-		.seq_show = bfqg_print_stat_recursive,
+		.seq_show_cft = bfqg_print_stat_recursive,
 	},
 	{
 		.name = "bfq.sectors_recursive",
@@ -1126,22 +1128,22 @@ struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.io_service_time_recursive",
 		.private = offsetof(struct bfq_group, stats.service_time),
-		.seq_show = bfqg_print_rwstat_recursive,
+		.seq_show_cft = bfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "bfq.io_wait_time_recursive",
 		.private = offsetof(struct bfq_group, stats.wait_time),
-		.seq_show = bfqg_print_rwstat_recursive,
+		.seq_show_cft = bfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "bfq.io_merged_recursive",
 		.private = offsetof(struct bfq_group, stats.merged),
-		.seq_show = bfqg_print_rwstat_recursive,
+		.seq_show_cft = bfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "bfq.io_queued_recursive",
 		.private = offsetof(struct bfq_group, stats.queued),
-		.seq_show = bfqg_print_rwstat_recursive,
+		.seq_show_cft = bfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "bfq.avg_queue_size",
@@ -1150,22 +1152,22 @@ struct cftype bfq_blkcg_legacy_files[] = {
 	{
 		.name = "bfq.group_wait_time",
 		.private = offsetof(struct bfq_group, stats.group_wait_time),
-		.seq_show = bfqg_print_stat,
+		.seq_show_cft = bfqg_print_stat,
 	},
 	{
 		.name = "bfq.idle_time",
 		.private = offsetof(struct bfq_group, stats.idle_time),
-		.seq_show = bfqg_print_stat,
+		.seq_show_cft = bfqg_print_stat,
 	},
 	{
 		.name = "bfq.empty_time",
 		.private = offsetof(struct bfq_group, stats.empty_time),
-		.seq_show = bfqg_print_stat,
+		.seq_show_cft = bfqg_print_stat,
 	},
 	{
 		.name = "bfq.dequeue",
 		.private = offsetof(struct bfq_group, stats.dequeue),
-		.seq_show = bfqg_print_stat,
+		.seq_show_cft = bfqg_print_stat,
 	},
 #endif	/* CONFIG_DEBUG_BLK_CGROUP */
 	{ }	/* terminate */
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 992da5592c6e..f173e7437203 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -667,15 +667,16 @@ static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
 /**
  * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes
  * @sf: seq_file to print to
+ * @cft: cftype holding the data
  * @v: unused
  *
  * To be used as cftype->seq_show to print blkg->stat_bytes.
  * cftype->private must be set to the blkcg_policy.
  */
-int blkg_print_stat_bytes(struct seq_file *sf, void *v)
+int blkg_print_stat_bytes(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-			  blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
+			  blkg_prfill_rwstat_field, (void *)cft->private,
 			  offsetof(struct blkcg_gq, stat_bytes), true);
 	return 0;
 }
@@ -684,15 +685,16 @@ EXPORT_SYMBOL_GPL(blkg_print_stat_bytes);
 /**
  * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios
  * @sf: seq_file to print to
+ * @cft: cftype holding the data
  * @v: unused
  *
  * To be used as cftype->seq_show to print blkg->stat_ios.  cftype->private
  * must be set to the blkcg_policy.
  */
-int blkg_print_stat_ios(struct seq_file *sf, void *v)
+int blkg_print_stat_ios(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-			  blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
+			  blkg_prfill_rwstat_field, (void *)cft->private,
 			  offsetof(struct blkcg_gq, stat_ios), true);
 	return 0;
 }
@@ -710,13 +712,15 @@ static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
 /**
  * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes
  * @sf: seq_file to print to
+ * @cft: cftype holding the data
  * @v: unused
  */
-int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v)
+int blkg_print_stat_bytes_recursive(struct seq_file *sf, struct cftype *cft,
+				    void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  blkg_prfill_rwstat_field_recursive,
-			  (void *)seq_cft(sf)->private,
+			  (void *)cft->private,
 			  offsetof(struct blkcg_gq, stat_bytes), true);
 	return 0;
 }
@@ -725,13 +729,15 @@ EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive);
 /**
  * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios
  * @sf: seq_file to print to
+ * @cft: cftype holding the data
  * @v: unused
  */
-int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
+int blkg_print_stat_ios_recursive(struct seq_file *sf, struct cftype *cft,
+				  void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  blkg_prfill_rwstat_field_recursive,
-			  (void *)seq_cft(sf)->private,
+			  (void *)cft->private,
 			  offsetof(struct blkcg_gq, stat_ios), true);
 	return 0;
 }
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 4bda70e8db48..5c43821dc528 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1493,22 +1493,22 @@ static struct cftype throtl_legacy_files[] = {
 	{
 		.name = "throttle.io_service_bytes",
 		.private = (unsigned long)&blkcg_policy_throtl,
-		.seq_show = blkg_print_stat_bytes,
+		.seq_show_cft = blkg_print_stat_bytes,
 	},
 	{
 		.name = "throttle.io_service_bytes_recursive",
 		.private = (unsigned long)&blkcg_policy_throtl,
-		.seq_show = blkg_print_stat_bytes_recursive,
+		.seq_show_cft = blkg_print_stat_bytes_recursive,
 	},
 	{
 		.name = "throttle.io_serviced",
 		.private = (unsigned long)&blkcg_policy_throtl,
-		.seq_show = blkg_print_stat_ios,
+		.seq_show_cft = blkg_print_stat_ios,
 	},
 	{
 		.name = "throttle.io_serviced_recursive",
 		.private = (unsigned long)&blkcg_policy_throtl,
-		.seq_show = blkg_print_stat_ios_recursive,
+		.seq_show_cft = blkg_print_stat_ios_recursive,
 	},
 	{ }	/* terminate */
 };
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6a3d87dd3c1a..af0c59c2dcde 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1884,17 +1884,17 @@ static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
 	return __cfq_set_weight(css, val, false, false, true);
 }
 
-static int cfqg_print_stat(struct seq_file *sf, void *v)
+static int cfqg_print_stat(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-			  &blkcg_policy_cfq, seq_cft(sf)->private, false);
+			  &blkcg_policy_cfq, cft->private, false);
 	return 0;
 }
 
-static int cfqg_print_rwstat(struct seq_file *sf, void *v)
+static int cfqg_print_rwstat(struct seq_file *sf, struct cftype *cft, void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
-			  &blkcg_policy_cfq, seq_cft(sf)->private, true);
+			  &blkcg_policy_cfq, cft->private, true);
 	return 0;
 }
 
@@ -1914,19 +1914,21 @@ static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
 	return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 
-static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
+static int cfqg_print_stat_recursive(struct seq_file *sf, struct cftype *cft,
+				     void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
-			  seq_cft(sf)->private, false);
+			  cft->private, false);
 	return 0;
 }
 
-static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
+static int cfqg_print_rwstat_recursive(struct seq_file *sf, struct cftype *cft,
+				       void *v)
 {
 	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
 			  cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
-			  seq_cft(sf)->private, true);
+			  cft->private, true);
 	return 0;
 }
 
@@ -2034,7 +2036,7 @@ static struct cftype cfq_blkcg_legacy_files[] = {
 	{
 		.name = "time",
 		.private = offsetof(struct cfq_group, stats.time),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 	{
 		.name = "sectors",
@@ -2043,39 +2045,39 @@ static struct cftype cfq_blkcg_legacy_files[] = {
 	{
 		.name = "io_service_bytes",
 		.private = (unsigned long)&blkcg_policy_cfq,
-		.seq_show = blkg_print_stat_bytes,
+		.seq_show_cft = blkg_print_stat_bytes,
 	},
 	{
 		.name = "io_serviced",
 		.private = (unsigned long)&blkcg_policy_cfq,
-		.seq_show = blkg_print_stat_ios,
+		.seq_show_cft = blkg_print_stat_ios,
 	},
 	{
 		.name = "io_service_time",
 		.private = offsetof(struct cfq_group, stats.service_time),
-		.seq_show = cfqg_print_rwstat,
+		.seq_show_cft = cfqg_print_rwstat,
 	},
 	{
 		.name = "io_wait_time",
 		.private = offsetof(struct cfq_group, stats.wait_time),
-		.seq_show = cfqg_print_rwstat,
+		.seq_show_cft = cfqg_print_rwstat,
 	},
 	{
 		.name = "io_merged",
 		.private = offsetof(struct cfq_group, stats.merged),
-		.seq_show = cfqg_print_rwstat,
+		.seq_show_cft = cfqg_print_rwstat,
 	},
 	{
 		.name = "io_queued",
 		.private = offsetof(struct cfq_group, stats.queued),
-		.seq_show = cfqg_print_rwstat,
+		.seq_show_cft = cfqg_print_rwstat,
 	},
 
 	/* the same statictics which cover the cfqg and its descendants */
 	{
 		.name = "time_recursive",
 		.private = offsetof(struct cfq_group, stats.time),
-		.seq_show = cfqg_print_stat_recursive,
+		.seq_show_cft = cfqg_print_stat_recursive,
 	},
 	{
 		.name = "sectors_recursive",
@@ -2084,32 +2086,32 @@ static struct cftype cfq_blkcg_legacy_files[] = {
 	{
 		.name = "io_service_bytes_recursive",
 		.private = (unsigned long)&blkcg_policy_cfq,
-		.seq_show = blkg_print_stat_bytes_recursive,
+		.seq_show_cft = blkg_print_stat_bytes_recursive,
 	},
 	{
 		.name = "io_serviced_recursive",
 		.private = (unsigned long)&blkcg_policy_cfq,
-		.seq_show = blkg_print_stat_ios_recursive,
+		.seq_show_cft = blkg_print_stat_ios_recursive,
 	},
 	{
 		.name = "io_service_time_recursive",
 		.private = offsetof(struct cfq_group, stats.service_time),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.seq_show_cft = cfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "io_wait_time_recursive",
 		.private = offsetof(struct cfq_group, stats.wait_time),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.seq_show_cft = cfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "io_merged_recursive",
 		.private = offsetof(struct cfq_group, stats.merged),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.seq_show_cft = cfqg_print_rwstat_recursive,
 	},
 	{
 		.name = "io_queued_recursive",
 		.private = offsetof(struct cfq_group, stats.queued),
-		.seq_show = cfqg_print_rwstat_recursive,
+		.seq_show_cft = cfqg_print_rwstat_recursive,
 	},
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	{
@@ -2119,27 +2121,27 @@ static struct cftype cfq_blkcg_legacy_files[] = {
 	{
 		.name = "group_wait_time",
 		.private = offsetof(struct cfq_group, stats.group_wait_time),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 	{
 		.name = "idle_time",
 		.private = offsetof(struct cfq_group, stats.idle_time),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 	{
 		.name = "empty_time",
 		.private = offsetof(struct cfq_group, stats.empty_time),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 	{
 		.name = "dequeue",
 		.private = offsetof(struct cfq_group, stats.dequeue),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 	{
 		.name = "unaccounted_time",
 		.private = offsetof(struct cfq_group, stats.unaccounted_time),
-		.seq_show = cfqg_print_stat,
+		.seq_show_cft = cfqg_print_stat,
 	},
 #endif	/* CONFIG_DEBUG_BLK_CGROUP */
 	{ }	/* terminate */
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 1e76ceebeb5d..7e016338724e 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -212,10 +212,12 @@ u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 		       int off);
-int blkg_print_stat_bytes(struct seq_file *sf, void *v);
-int blkg_print_stat_ios(struct seq_file *sf, void *v);
-int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
-int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
+int blkg_print_stat_bytes(struct seq_file *sf, struct cftype *cft, void *v);
+int blkg_print_stat_ios(struct seq_file *sf, struct cftype *cft, void *v);
+int blkg_print_stat_bytes_recursive(struct seq_file *sf, struct cftype *cft,
+				    void *v);
+int blkg_print_stat_ios_recursive(struct seq_file *sf, struct cftype *cft,
+				  void *v);
 
 u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
 			    struct blkcg_policy *pol, int off);
-- 
2.16.1