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 <angeloruocc...@gmail.com>
Signed-off-by: Paolo Valente <paolo.vale...@linaro.org>
---
 block/bfq-cgroup.c         | 54 ++++++++++++++++++++++++----------------------
 block/blk-cgroup.c         | 22 ++++++++++++-------
 block/blk-throttle.c       |  8 +++----
 include/linux/blk-cgroup.h | 10 +++++----
 4 files changed, 52 insertions(+), 42 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index a7a1712632b0..038e418fa64f 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 63d226a084cd..772d32bbecae 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -565,15 +565,16 @@ 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;
 }
@@ -582,15 +583,16 @@ 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;
 }
@@ -608,13 +610,15 @@ 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;
 }
@@ -623,13 +627,15 @@ 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 8f0a104770ee..6bfdaac53b6f 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/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index a9e2e2037129..770b59e0d35f 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -207,10 +207,12 @@ 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

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