[PATCH v7 28/31] ext4: add tracepoints for DISKSIZE_GROW_PENDING set, clear, and wait

[Zhang Yi]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

Add trace events ext4_iomap_mark_disksize_pending(),
ext4_iomap_clear_disksize_pending(), and
ext4_iomap_wait_disksize_pending() to track disksize-grow-pending
state changes and waiting.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/inode.c             | 15 ++++++++++++---
 include/trace/events/ext4.h | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3bdb5f3b119ab..920760ab6ea7b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -133,9 +133,12 @@ void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
  */
 void ext4_iomap_clear_disksize_pending(struct inode *inode)
 {
-	clear_and_wake_up_bit(
+	if (!test_and_clear_wake_up_bit(
 		ext4_inode_state_wait_bit(EXT4_STATE_DISKSIZE_GROW_PENDING),
-		ext4_inode_state_wait_word(inode));
+		ext4_inode_state_wait_word(inode)))
+		return;
+
+	trace_ext4_iomap_clear_disksize_pending(inode);
 }
 
 /*
@@ -144,6 +147,10 @@ void ext4_iomap_clear_disksize_pending(struct inode *inode)
  */
 void ext4_iomap_wait_disksize_pending(struct inode *inode)
 {
+	/* Only emit the trace when the bit is actually set */
+	if (ext4_test_inode_state(inode, EXT4_STATE_DISKSIZE_GROW_PENDING))
+		trace_ext4_iomap_wait_disksize_pending(inode);
+
 	wait_on_bit(ext4_inode_state_wait_word(inode),
 		    ext4_inode_state_wait_bit(EXT4_STATE_DISKSIZE_GROW_PENDING),
 		    TASK_UNINTERRUPTIBLE);
@@ -4922,8 +4929,10 @@ static int ext4_iomap_mark_disksize_pending(struct inode *inode, loff_t from)
 	 */
 	if (likely(folio_test_dirty(folio) &&
 		   !ext4_test_inode_state(inode,
-					  EXT4_STATE_DISKSIZE_GROW_PENDING)))
+					  EXT4_STATE_DISKSIZE_GROW_PENDING))) {
+		trace_ext4_iomap_mark_disksize_pending(inode);
 		ext4_set_inode_state(inode, EXT4_STATE_DISKSIZE_GROW_PENDING);
+	}
 out:
 	folio_unlock(folio);
 	folio_put(folio);
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index bcf80f518e61d..d33456d06b001 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -3204,6 +3204,39 @@ 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);
 
+DECLARE_EVENT_CLASS(ext4_iomap_disksize_pending,
+	TP_PROTO(struct inode *inode),
+	TP_ARGS(inode),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u64, ino)
+		__field(loff_t, i_disksize)
+	),
+	TP_fast_assign(
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->ino = inode->i_ino;
+		__entry->i_disksize = READ_ONCE(EXT4_I(inode)->i_disksize);
+	),
+	TP_printk("dev %d:%d ino %llu i_disksize %lld",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->ino, __entry->i_disksize)
+);
+
+DEFINE_EVENT(ext4_iomap_disksize_pending, ext4_iomap_mark_disksize_pending,
+	TP_PROTO(struct inode *inode),
+	TP_ARGS(inode)
+);
+
+DEFINE_EVENT(ext4_iomap_disksize_pending, ext4_iomap_clear_disksize_pending,
+	TP_PROTO(struct inode *inode),
+	TP_ARGS(inode)
+);
+
+DEFINE_EVENT(ext4_iomap_disksize_pending, ext4_iomap_wait_disksize_pending,
+	TP_PROTO(struct inode *inode),
+	TP_ARGS(inode)
+);
+
 #endif /* _TRACE_EXT4_H */
 
 /* This part must be outside protection */
-- 
2.52.0