writeback: add more tracepoints

Add tracepoints for page dirtying, writeback_single_inode start, inode
dirtying and writeback.  For the latter two inode events, a pair of
events are defined to denote start and end of the operations (the
starting one has _start suffix and the one w/o suffix happens after
the operation is complete).  These inode ops are FS specific and can
be non-trivial and having enclosing tracepoints is useful for external
tracers.

This is part of tracepoint additions to improve visiblity into
dirtying / writeback operations for io tracer and userland.

v2: writeback_dirty_inode[_start] TPs may be called for files on
    pseudo FSes w/ unregistered bdi.  Check whether bdi->dev is %NULL
    before dereferencing.

v3: buffer dirtying moved to a block TP.

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

1 files changed, 116 insertions, 0 deletions

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index b453d92c2253..6a16fd2e70ed 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -32,6 +32,115 @@
 
 struct wb_writeback_work;
 
+TRACE_EVENT(writeback_dirty_page,
+
+        TP_PROTO(struct page *page, struct address_space *mapping),
+
+        TP_ARGS(page, mapping),
+
+        TP_STRUCT__entry (
+                __array(char, name, 32)
+                __field(unsigned long, ino)
+                __field(pgoff_t, index)
+        ),
+
+        TP_fast_assign(
+                strncpy(__entry->name,
+                        mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)", 32);
+                __entry->ino = mapping ? mapping->host->i_ino : 0;
+                __entry->index = page->index;
+        ),
+
+        TP_printk("bdi %s: ino=%lu index=%lu",
+                __entry->name,
+                __entry->ino,
+                __entry->index
+        )
+);
+
+DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
+
+        TP_PROTO(struct inode *inode, int flags),
+
+        TP_ARGS(inode, flags),
+
+        TP_STRUCT__entry (
+                __array(char, name, 32)
+                __field(unsigned long, ino)
+                __field(unsigned long, flags)
+        ),
+
+        TP_fast_assign(
+                struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
+
+                /* may be called for files on pseudo FSes w/ unregistered bdi */
+                strncpy(__entry->name,
+                        bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+                __entry->ino            = inode->i_ino;
+                __entry->flags          = flags;
+        ),
+
+        TP_printk("bdi %s: ino=%lu flags=%s",
+                __entry->name,
+                __entry->ino,
+                show_inode_state(__entry->flags)
+        )
+);
+
+DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode_start,
+
+        TP_PROTO(struct inode *inode, int flags),
+
+        TP_ARGS(inode, flags)
+);
+
+DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
+
+        TP_PROTO(struct inode *inode, int flags),
+
+        TP_ARGS(inode, flags)
+);
+
+DECLARE_EVENT_CLASS(writeback_write_inode_template,
+
+        TP_PROTO(struct inode *inode, struct writeback_control *wbc),
+
+        TP_ARGS(inode, wbc),
+
+        TP_STRUCT__entry (
+                __array(char, name, 32)
+                __field(unsigned long, ino)
+                __field(int, sync_mode)
+        ),
+
+        TP_fast_assign(
+                strncpy(__entry->name,
+                        dev_name(inode->i_mapping->backing_dev_info->dev), 32);
+                __entry->ino            = inode->i_ino;
+                __entry->sync_mode      = wbc->sync_mode;
+        ),
+
+        TP_printk("bdi %s: ino=%lu sync_mode=%d",
+                __entry->name,
+                __entry->ino,
+                __entry->sync_mode
+        )
+);
+
+DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode_start,
+
+        TP_PROTO(struct inode *inode, struct writeback_control *wbc),
+
+        TP_ARGS(inode, wbc)
+);
+
+DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode,
+
+        TP_PROTO(struct inode *inode, struct writeback_control *wbc),
+
+        TP_ARGS(inode, wbc)
+);
+
 DECLARE_EVENT_CLASS(writeback_work_class,
         TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
         TP_ARGS(bdi, work),
@@ -479,6 +588,13 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
         )
 );
 
+DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode_start,
+        TP_PROTO(struct inode *inode,
+                 struct writeback_control *wbc,
+                 unsigned long nr_to_write),
+        TP_ARGS(inode, wbc, nr_to_write)
+);
+
 DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode,
         TP_PROTO(struct inode *inode,
                  struct writeback_control *wbc,