writeback: update writeback tracepoints to report cgroup

The following tracepoints are updated to report the cgroup used during
cgroup writeback.

* writeback_write_inode[_start]
* writeback_queue
* writeback_exec
* writeback_start
* writeback_written
* writeback_wait
* writeback_nowork
* writeback_wake_background
* wbc_writepage
* writeback_queue_io
* bdi_dirty_ratelimit
* balance_dirty_pages
* writeback_sb_inodes_requeue
* writeback_single_inode[_start]

Note that writeback_bdi_register is separated out from writeback_class
as reporting cgroup doesn't make sense to it.  Tracepoints which take
bdi are updated to take bdi_writeback instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 141 insertions, 39 deletions

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index a7aa607a4c55..fff846b512e6 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -131,6 +131,66 @@ DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
         TP_ARGS(inode, flags)
 );
 
+#ifdef CREATE_TRACE_POINTS
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+        return kernfs_path_len(wb->memcg_css->cgroup->kn) + 1;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+        struct cgroup *cgrp = wb->memcg_css->cgroup;
+        char *path;
+
+        path = cgroup_path(cgrp, buf, kernfs_path_len(cgrp->kn) + 1);
+        WARN_ON_ONCE(path != buf);
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+        if (wbc->wb)
+                return __trace_wb_cgroup_size(wbc->wb);
+        else
+                return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+                                             struct writeback_control *wbc)
+{
+        if (wbc->wb)
+                __trace_wb_assign_cgroup(buf, wbc->wb);
+        else
+                strcpy(buf, "/");
+}
+
+#else   /* CONFIG_CGROUP_WRITEBACK */
+
+static inline size_t __trace_wb_cgroup_size(struct bdi_writeback *wb)
+{
+        return 2;
+}
+
+static inline void __trace_wb_assign_cgroup(char *buf, struct bdi_writeback *wb)
+{
+        strcpy(buf, "/");
+}
+
+static inline size_t __trace_wbc_cgroup_size(struct writeback_control *wbc)
+{
+        return 2;
+}
+
+static inline void __trace_wbc_assign_cgroup(char *buf,
+                                             struct writeback_control *wbc)
+{
+        strcpy(buf, "/");
+}
+
+#endif  /* CONFIG_CGROUP_WRITEBACK */
+#endif  /* CREATE_TRACE_POINTS */
+
 DECLARE_EVENT_CLASS(writeback_write_inode_template,
 
         TP_PROTO(struct inode *inode, struct writeback_control *wbc),
@@ -141,6 +201,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
                 __array(char, name, 32)
                 __field(unsigned long, ino)
                 __field(int, sync_mode)
+                __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
         ),
 
         TP_fast_assign(
@@ -148,12 +209,14 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
                         dev_name(inode_to_bdi(inode)->dev), 32);
                 __entry->ino            = inode->i_ino;
                 __entry->sync_mode      = wbc->sync_mode;
+                __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
         ),
 
-        TP_printk("bdi %s: ino=%lu sync_mode=%d",
+        TP_printk("bdi %s: ino=%lu sync_mode=%d cgroup=%s",
                 __entry->name,
                 __entry->ino,
-                __entry->sync_mode
+                __entry->sync_mode,
+                __get_str(cgroup)
         )
 );
 
@@ -172,8 +235,8 @@ DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode,
 );
 
 DECLARE_EVENT_CLASS(writeback_work_class,
-        TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
-        TP_ARGS(bdi, work),
+        TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work),
+        TP_ARGS(wb, work),
         TP_STRUCT__entry(
                 __array(char, name, 32)
                 __field(long, nr_pages)
@@ -183,10 +246,11 @@ DECLARE_EVENT_CLASS(writeback_work_class,
                 __field(int, range_cyclic)
                 __field(int, for_background)
                 __field(int, reason)
+                __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
         ),
         TP_fast_assign(
                 strncpy(__entry->name,
-                        bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+                        wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
                 __entry->nr_pages = work->nr_pages;
                 __entry->sb_dev = work->sb ? work->sb->s_dev : 0;
                 __entry->sync_mode = work->sync_mode;
@@ -194,9 +258,10 @@ DECLARE_EVENT_CLASS(writeback_work_class,
                 __entry->range_cyclic = work->range_cyclic;
                 __entry->for_background = work->for_background;
                 __entry->reason = work->reason;
+                __trace_wb_assign_cgroup(__get_str(cgroup), wb);
         ),
         TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
-                  "kupdate=%d range_cyclic=%d background=%d reason=%s",
+                  "kupdate=%d range_cyclic=%d background=%d reason=%s cgroup=%s",
                   __entry->name,
                   MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev),
                   __entry->nr_pages,
@@ -204,13 +269,14 @@ DECLARE_EVENT_CLASS(writeback_work_class,
                   __entry->for_kupdate,
                   __entry->range_cyclic,
                   __entry->for_background,
-                  __print_symbolic(__entry->reason, WB_WORK_REASON)
+                  __print_symbolic(__entry->reason, WB_WORK_REASON),
+                  __get_str(cgroup)
         )
 );
 #define DEFINE_WRITEBACK_WORK_EVENT(name) \
 DEFINE_EVENT(writeback_work_class, name, \
-        TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work), \
-        TP_ARGS(bdi, work))
+        TP_PROTO(struct bdi_writeback *wb, struct wb_writeback_work *work), \
+        TP_ARGS(wb, work))
 DEFINE_WRITEBACK_WORK_EVENT(writeback_queue);
 DEFINE_WRITEBACK_WORK_EVENT(writeback_exec);
 DEFINE_WRITEBACK_WORK_EVENT(writeback_start);
@@ -230,26 +296,42 @@ TRACE_EVENT(writeback_pages_written,
 );
 
 DECLARE_EVENT_CLASS(writeback_class,
-        TP_PROTO(struct backing_dev_info *bdi),
-        TP_ARGS(bdi),
+        TP_PROTO(struct bdi_writeback *wb),
+        TP_ARGS(wb),
         TP_STRUCT__entry(
                 __array(char, name, 32)
+                __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
         ),
         TP_fast_assign(
-                strncpy(__entry->name, dev_name(bdi->dev), 32);
+                strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+                __trace_wb_assign_cgroup(__get_str(cgroup), wb);
         ),
-        TP_printk("bdi %s",
-                  __entry->name
+        TP_printk("bdi %s: cgroup=%s",
+                  __entry->name,
+                  __get_str(cgroup)
         )
 );
 #define DEFINE_WRITEBACK_EVENT(name) \
 DEFINE_EVENT(writeback_class, name, \
-        TP_PROTO(struct backing_dev_info *bdi), \
-        TP_ARGS(bdi))
+        TP_PROTO(struct bdi_writeback *wb), \
+        TP_ARGS(wb))
 
 DEFINE_WRITEBACK_EVENT(writeback_nowork);
 DEFINE_WRITEBACK_EVENT(writeback_wake_background);
-DEFINE_WRITEBACK_EVENT(writeback_bdi_register);
+
+TRACE_EVENT(writeback_bdi_register,
+        TP_PROTO(struct backing_dev_info *bdi),
+        TP_ARGS(bdi),
+        TP_STRUCT__entry(
+                __array(char, name, 32)
+        ),
+        TP_fast_assign(
+                strncpy(__entry->name, dev_name(bdi->dev), 32);
+        ),
+        TP_printk("bdi %s",
+                __entry->name
+        )
+);
 
 DECLARE_EVENT_CLASS(wbc_class,
         TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi),
@@ -265,6 +347,7 @@ DECLARE_EVENT_CLASS(wbc_class,
                 __field(int, range_cyclic)
                 __field(long, range_start)
                 __field(long, range_end)
+                __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
         ),
 
         TP_fast_assign(
@@ -278,11 +361,12 @@ DECLARE_EVENT_CLASS(wbc_class,
                 __entry->range_cyclic   = wbc->range_cyclic;
                 __entry->range_start    = (long)wbc->range_start;
                 __entry->range_end      = (long)wbc->range_end;
+                __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
         ),
 
         TP_printk("bdi %s: towrt=%ld skip=%ld mode=%d kupd=%d "
                 "bgrd=%d reclm=%d cyclic=%d "
-                "start=0x%lx end=0x%lx",
+                "start=0x%lx end=0x%lx cgroup=%s",
                 __entry->name,
                 __entry->nr_to_write,
                 __entry->pages_skipped,
@@ -292,7 +376,9 @@ DECLARE_EVENT_CLASS(wbc_class,
                 __entry->for_reclaim,
                 __entry->range_cyclic,
                 __entry->range_start,
-                __entry->range_end)
+                __entry->range_end,
+                __get_str(cgroup)
+        )
 )
 
 #define DEFINE_WBC_EVENT(name) \
@@ -312,6 +398,7 @@ TRACE_EVENT(writeback_queue_io,
                 __field(long,           age)
                 __field(int,            moved)
                 __field(int,            reason)
+                __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
         ),
         TP_fast_assign(
                 unsigned long *older_than_this = work->older_than_this;
@@ -321,13 +408,15 @@ TRACE_EVENT(writeback_queue_io,
                                   (jiffies - *older_than_this) * 1000 / HZ : -1;
                 __entry->moved  = moved;
                 __entry->reason = work->reason;
+                __trace_wb_assign_cgroup(__get_str(cgroup), wb);
         ),
-        TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s",
+        TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s cgroup=%s",
                 __entry->name,
                 __entry->older, /* older_than_this in jiffies */
                 __entry->age,   /* older_than_this in relative milliseconds */
                 __entry->moved,
-                __print_symbolic(__entry->reason, WB_WORK_REASON)
+                __print_symbolic(__entry->reason, WB_WORK_REASON),
+                __get_str(cgroup)
         )
 );
 
@@ -381,11 +470,11 @@ TRACE_EVENT(global_dirty_state,
 
 TRACE_EVENT(bdi_dirty_ratelimit,
 
-        TP_PROTO(struct backing_dev_info *bdi,
+        TP_PROTO(struct bdi_writeback *wb,
                  unsigned long dirty_rate,
                  unsigned long task_ratelimit),
 
-        TP_ARGS(bdi, dirty_rate, task_ratelimit),
+        TP_ARGS(wb, dirty_rate, task_ratelimit),
 
         TP_STRUCT__entry(
                 __array(char,           bdi, 32)
@@ -395,36 +484,39 @@ TRACE_EVENT(bdi_dirty_ratelimit,
                 __field(unsigned long,  dirty_ratelimit)
                 __field(unsigned long,  task_ratelimit)
                 __field(unsigned long,  balanced_dirty_ratelimit)
+                __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
         ),
 
         TP_fast_assign(
-                strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
-                __entry->write_bw       = KBps(bdi->wb.write_bandwidth);
-                __entry->avg_write_bw   = KBps(bdi->wb.avg_write_bandwidth);
+                strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+                __entry->write_bw       = KBps(wb->write_bandwidth);
+                __entry->avg_write_bw   = KBps(wb->avg_write_bandwidth);
                 __entry->dirty_rate     = KBps(dirty_rate);
-                __entry->dirty_ratelimit = KBps(bdi->wb.dirty_ratelimit);
+                __entry->dirty_ratelimit = KBps(wb->dirty_ratelimit);
                 __entry->task_ratelimit = KBps(task_ratelimit);
                 __entry->balanced_dirty_ratelimit =
-                                        KBps(bdi->wb.balanced_dirty_ratelimit);
+                                        KBps(wb->balanced_dirty_ratelimit);
+                __trace_wb_assign_cgroup(__get_str(cgroup), wb);
         ),
 
         TP_printk("bdi %s: "
                   "write_bw=%lu awrite_bw=%lu dirty_rate=%lu "
                   "dirty_ratelimit=%lu task_ratelimit=%lu "
-                  "balanced_dirty_ratelimit=%lu",
+                  "balanced_dirty_ratelimit=%lu cgroup=%s",
                   __entry->bdi,
                   __entry->write_bw,            /* write bandwidth */
                   __entry->avg_write_bw,        /* avg write bandwidth */
                   __entry->dirty_rate,          /* bdi dirty rate */
                   __entry->dirty_ratelimit,     /* base ratelimit */
                   __entry->task_ratelimit, /* ratelimit with position control */
-                  __entry->balanced_dirty_ratelimit /* the balanced ratelimit */
+                  __entry->balanced_dirty_ratelimit, /* the balanced ratelimit */
+                  __get_str(cgroup)
         )
 );
 
 TRACE_EVENT(balance_dirty_pages,
 
-        TP_PROTO(struct backing_dev_info *bdi,
+        TP_PROTO(struct bdi_writeback *wb,
                  unsigned long thresh,
                  unsigned long bg_thresh,
                  unsigned long dirty,
@@ -437,7 +529,7 @@ TRACE_EVENT(balance_dirty_pages,
                  long pause,
                  unsigned long start_time),
 
-        TP_ARGS(bdi, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
+        TP_ARGS(wb, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
                 dirty_ratelimit, task_ratelimit,
                 dirtied, period, pause, start_time),
 
@@ -456,11 +548,12 @@ TRACE_EVENT(balance_dirty_pages,
                 __field(         long,  pause)
                 __field(unsigned long,  period)
                 __field(         long,  think)
+                __dynamic_array(char, cgroup, __trace_wb_cgroup_size(wb))
         ),
 
         TP_fast_assign(
                 unsigned long freerun = (thresh + bg_thresh) / 2;
-                strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
+                strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
 
                 __entry->limit          = global_wb_domain.dirty_limit;
                 __entry->setpoint       = (global_wb_domain.dirty_limit +
@@ -478,6 +571,7 @@ TRACE_EVENT(balance_dirty_pages,
                 __entry->period         = period * 1000 / HZ;
                 __entry->pause          = pause * 1000 / HZ;
                 __entry->paused         = (jiffies - start_time) * 1000 / HZ;
+                __trace_wb_assign_cgroup(__get_str(cgroup), wb);
         ),
 
 
@@ -486,7 +580,7 @@ TRACE_EVENT(balance_dirty_pages,
                   "bdi_setpoint=%lu bdi_dirty=%lu "
                   "dirty_ratelimit=%lu task_ratelimit=%lu "
                   "dirtied=%u dirtied_pause=%u "
-                  "paused=%lu pause=%ld period=%lu think=%ld",
+                  "paused=%lu pause=%ld period=%lu think=%ld cgroup=%s",
                   __entry->bdi,
                   __entry->limit,
                   __entry->setpoint,
@@ -500,7 +594,8 @@ TRACE_EVENT(balance_dirty_pages,
                   __entry->paused,      /* ms */
                   __entry->pause,       /* ms */
                   __entry->period,      /* ms */
-                  __entry->think        /* ms */
+                  __entry->think,       /* ms */
+                  __get_str(cgroup)
           )
 );
 
@@ -514,6 +609,8 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
                 __field(unsigned long, ino)
                 __field(unsigned long, state)
                 __field(unsigned long, dirtied_when)
+                __dynamic_array(char, cgroup,
+                                __trace_wb_cgroup_size(inode_to_wb(inode)))
         ),
 
         TP_fast_assign(
@@ -522,14 +619,16 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
                 __entry->ino            = inode->i_ino;
                 __entry->state          = inode->i_state;
                 __entry->dirtied_when   = inode->dirtied_when;
+                __trace_wb_assign_cgroup(__get_str(cgroup), inode_to_wb(inode));
         ),
 
-        TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu",
+        TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu cgroup=%s",
                   __entry->name,
                   __entry->ino,
                   show_inode_state(__entry->state),
                   __entry->dirtied_when,
-                  (jiffies - __entry->dirtied_when) / HZ
+                  (jiffies - __entry->dirtied_when) / HZ,
+                  __get_str(cgroup)
         )
 );
 
@@ -585,6 +684,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
                 __field(unsigned long, writeback_index)
                 __field(long, nr_to_write)
                 __field(unsigned long, wrote)
+                __dynamic_array(char, cgroup, __trace_wbc_cgroup_size(wbc))
         ),
 
         TP_fast_assign(
@@ -596,10 +696,11 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
                 __entry->writeback_index = inode->i_mapping->writeback_index;
                 __entry->nr_to_write    = nr_to_write;
                 __entry->wrote          = nr_to_write - wbc->nr_to_write;
+                __trace_wbc_assign_cgroup(__get_str(cgroup), wbc);
         ),
 
         TP_printk("bdi %s: ino=%lu state=%s dirtied_when=%lu age=%lu "
-                  "index=%lu to_write=%ld wrote=%lu",
+                  "index=%lu to_write=%ld wrote=%lu cgroup=%s",
                   __entry->name,
                   __entry->ino,
                   show_inode_state(__entry->state),
@@ -607,7 +708,8 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
                   (jiffies - __entry->dirtied_when) / HZ,
                   __entry->writeback_index,
                   __entry->nr_to_write,
-                  __entry->wrote
+                  __entry->wrote,
+                  __get_str(cgroup)
         )
 );