[PATCH v4 15/23] ext4: add block mapping tracepoints for iomap buffered I/O path

[Zhang Yi]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

Add tracepoints for iomap buffered read, write, partial block zeroing,
and writeback operations to help debug the iomap buffered I/O path.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/inode.c             |  6 +++++
 include/trace/events/ext4.h | 45 +++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e0dae2501292..239d387ffaf2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3961,6 +3961,8 @@ static int ext4_iomap_buffered_read_begin(struct inode *inode, loff_t offset,
 	if (ret < 0)
 		return ret;
 
+	trace_ext4_iomap_buffered_read_begin(inode, &map, offset, length,
+					     flags);
 	ext4_set_iomap(inode, iomap, &map, offset, length, flags);
 	return 0;
 }
@@ -4034,6 +4036,8 @@ static int ext4_iomap_buffered_do_write_begin(struct inode *inode,
 	if (ret < 0)
 		return ret;
 
+	trace_ext4_iomap_buffered_write_begin(inode, &map, offset, length,
+					      flags);
 	ext4_set_iomap(inode, iomap, &map, offset, length, flags);
 	return 0;
 }
@@ -4136,6 +4140,7 @@ static int ext4_iomap_zero_begin(struct inode *inode,
 			map.m_len = (start >> blkbits) - map.m_lblk;
 	}
 
+	trace_ext4_iomap_zero_begin(inode, &map, offset, length, flags);
 	ext4_set_iomap(inode, iomap, &map, offset, length, flags);
 	iomap->flags |= iomap_flags;
 
@@ -4308,6 +4313,7 @@ static int ext4_iomap_map_writeback_range(struct iomap_writepage_ctx *wpc,
 		return ret;
 	}
 out:
+	trace_ext4_iomap_map_writeback_range(inode, &map, offset, dirty_len, 0);
 	ext4_set_iomap(inode, &wpc->iomap, &map, offset, dirty_len, 0);
 	return 0;
 }
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index f493642cf121..ebafa06cd191 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -3096,6 +3096,51 @@ TRACE_EVENT(ext4_move_extent_exit,
 		  __entry->ret)
 );
 
+DECLARE_EVENT_CLASS(ext4_set_iomap_class,
+	TP_PROTO(struct inode *inode, struct ext4_map_blocks *map,
+		 loff_t offset, loff_t length, unsigned int flags),
+	TP_ARGS(inode, map, offset, length, flags),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u64, ino)
+		__field(ext4_lblk_t, m_lblk)
+		__field(unsigned int, m_len)
+		__field(unsigned int, m_flags)
+		__field(u64, m_seq)
+		__field(loff_t, offset)
+		__field(loff_t, length)
+		__field(unsigned int, iomap_flags)
+	),
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->m_lblk		= map->m_lblk;
+		__entry->m_len		= map->m_len;
+		__entry->m_flags	= map->m_flags;
+		__entry->m_seq		= map->m_seq;
+		__entry->offset		= offset;
+		__entry->length		= length;
+		__entry->iomap_flags	= flags;
+
+	),
+	TP_printk("dev %d:%d ino %llu m_lblk %u m_len %u m_flags %s m_seq %llu orig_off 0x%llx orig_len 0x%llx iomap_flags 0x%x",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->ino, __entry->m_lblk, __entry->m_len,
+		  show_mflags(__entry->m_flags), __entry->m_seq,
+		  __entry->offset, __entry->length, __entry->iomap_flags)
+)
+
+#define DEFINE_SET_IOMAP_EVENT(name) \
+DEFINE_EVENT(ext4_set_iomap_class, name, \
+	TP_PROTO(struct inode *inode, struct ext4_map_blocks *map, \
+		 loff_t offset, loff_t length, unsigned int flags), \
+	TP_ARGS(inode, map, offset, length, flags))
+
+DEFINE_SET_IOMAP_EVENT(ext4_iomap_buffered_read_begin);
+DEFINE_SET_IOMAP_EVENT(ext4_iomap_buffered_write_begin);
+DEFINE_SET_IOMAP_EVENT(ext4_iomap_map_writeback_range);
+DEFINE_SET_IOMAP_EVENT(ext4_iomap_zero_begin);
+
 #endif /* _TRACE_EXT4_H */
 
 /* This part must be outside protection */
-- 
2.52.0