[PATCH -next v5 30/32] ext4: add tracepoints for EOF block zeroing and disksize-grow I/O

[Zhang Yi]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

Add tracepoints to track the disksize-grow-pending lifecycle in the
writeback path and the block-zero-EOF entry point:

- ext4_iomap_wb_disksize_pending_submit: ioend is marked as
  DISKSIZE_GROW_IO in ext4_iomap_writeback_submit.
- ext4_iomap_wb_disksize_pending_complete: ioend of type
  DISKSIZE_GROW_IO completes in ext4_iomap_end_bio.
- ext4_iomap_wb_disksize_pending_wait: ioend worker waits for the
  pending zeroed EOF block to complete.
- ext4_iomap_wb_update_disksize: i_disksize is advanced in
  ext4_iomap_wb_update_disksize, including the new value and
  whether the update is a disksize-grow completion.
- ext4_block_zero_eof: ext4_block_zero_eof is called with the range
  and zeroing outcome, capturing the producer-side entry point.

Together with the previous mark/clear/wait tracepoints, these cover the
full lifetime of the disksize-grow-pending state.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/inode.c             |   3 +
 fs/ext4/page-io.c           |  13 ++++-
 include/trace/events/ext4.h | 107 ++++++++++++++++++++++++++++++++++++
 3 files changed, 121 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bca7d5c33919..ee15366422a1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4406,6 +4406,8 @@ static int ext4_iomap_writeback_submit(struct iomap_writepage_ctx *wpc,
 	    round_down(ioend->io_offset, blocksize) <= pstart &&
 	    round_up(ioend->io_offset + ioend->io_size, blocksize) >=
 			pstart + plen) {
+		trace_ext4_iomap_wb_disksize_pending_submit(inode,
+				ioend->io_offset, ioend->io_size);
 		ioend->io_bio.bi_end_io = ext4_iomap_end_bio;
 		ioend->io_private = (void *)EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO;
 	}
@@ -5001,6 +5003,7 @@ int ext4_block_zero_eof(struct inode *inode, loff_t from, loff_t end)
 			return err;
 	}
 
+	trace_ext4_block_zero_eof(inode, from, length, did_zero, zero_written);
 	return 0;
 }
 
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 4f1176b9332f..4464eb03c972 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -31,6 +31,8 @@
 #include "xattr.h"
 #include "acl.h"
 
+#include <trace/events/ext4.h>
+
 static struct kmem_cache *io_end_cachep;
 static struct kmem_cache *io_end_vec_cachep;
 
@@ -574,6 +576,7 @@ static void ext4_iomap_wb_disksize_pending_wait(struct inode *inode,
 	if (!plen || pos < pstart + plen)
 		return;
 
+	trace_ext4_iomap_wb_disksize_pending_wait(inode, pos, size);
 	ext4_iomap_wait_disksize_pending(inode);
 }
 
@@ -617,8 +620,11 @@ static int ext4_iomap_wb_update_disksize(handle_t *handle, struct inode *inode,
 	 * after the data has been persisted.
 	 */
 	new_disksize = is_disksize_grow ? i_size : min(end, i_size);
-	if (new_disksize > ei->i_disksize)
+	if (new_disksize > ei->i_disksize) {
+		trace_ext4_iomap_wb_update_disksize(inode, end, i_size,
+				ei->i_disksize, new_disksize, is_disksize_grow);
 		WRITE_ONCE(ei->i_disksize, new_disksize);
+	}
 	up_write(&ei->i_data_sem);
 	ret = ext4_mark_inode_dirty(handle, inode);
 	if (ret)
@@ -729,8 +735,11 @@ void ext4_iomap_end_bio(struct bio *bio)
 	 * state set in ext4_block_zero_eof() and wake up all waiters
 	 * that will update the inode i_disksize.
 	 */
-	if (io_mode == EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO)
+	if (io_mode == EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO) {
+		trace_ext4_iomap_wb_disksize_pending_complete(ioend->io_inode,
+				ioend->io_offset, ioend->io_size);
 		ext4_iomap_clear_disksize_pending(ioend->io_inode);
+	}
 
 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
 	if (list_empty(&ei->i_rsv_conversion_list))
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 4539ef8e5f86..c9259c2a3e36 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -3237,6 +3237,113 @@ DEFINE_EVENT(ext4_iomap_disksize_pending, ext4_iomap_wait_disksize_pending,
 	TP_ARGS(inode)
 );
 
+/* disksize pending I/O tracepoints for iomap Buffered I/O path */
+DECLARE_EVENT_CLASS(ext4_iomap_wb_disksize_pending,
+	TP_PROTO(struct inode *inode, loff_t io_offset, size_t io_size),
+	TP_ARGS(inode, io_offset, io_size),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u64, ino)
+		__field(loff_t, io_offset)
+		__field(size_t, io_size)
+		__field(loff_t, i_size)
+		__field(loff_t, i_disksize)
+	),
+	TP_fast_assign(
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->ino = inode->i_ino;
+		__entry->io_offset = io_offset;
+		__entry->io_size = io_size;
+		__entry->i_size = i_size_read(inode);
+		__entry->i_disksize = READ_ONCE(EXT4_I(inode)->i_disksize);
+	),
+	TP_printk("dev %d:%d ino %llu io_offset %lld io_size %zu i_size %lld i_disksize %lld",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->ino, __entry->io_offset, __entry->io_size,
+		  __entry->i_size, __entry->i_disksize)
+);
+
+DEFINE_EVENT(ext4_iomap_wb_disksize_pending,
+	ext4_iomap_wb_disksize_pending_submit,
+	TP_PROTO(struct inode *inode, loff_t io_offset, size_t io_size),
+	TP_ARGS(inode, io_offset, io_size)
+);
+
+DEFINE_EVENT(ext4_iomap_wb_disksize_pending,
+	ext4_iomap_wb_disksize_pending_complete,
+	TP_PROTO(struct inode *inode, loff_t io_offset, size_t io_size),
+	TP_ARGS(inode, io_offset, io_size)
+);
+
+DEFINE_EVENT(ext4_iomap_wb_disksize_pending,
+	ext4_iomap_wb_disksize_pending_wait,
+	TP_PROTO(struct inode *inode, loff_t io_offset, size_t io_size),
+	TP_ARGS(inode, io_offset, io_size)
+);
+
+/* i_disksize update tracepoint */
+TRACE_EVENT(ext4_iomap_wb_update_disksize,
+	TP_PROTO(struct inode *inode, loff_t end, loff_t i_size,
+		 loff_t i_disksize, loff_t new_disksize,
+		 bool is_disksize_grow),
+	TP_ARGS(inode, end, i_size, i_disksize, new_disksize,
+		is_disksize_grow),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u64, ino)
+		__field(loff_t, end)
+		__field(loff_t, i_size)
+		__field(loff_t, i_disksize)
+		__field(loff_t, new_disksize)
+		__field(bool, is_disksize_grow)
+	),
+	TP_fast_assign(
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->ino = inode->i_ino;
+		__entry->end = end;
+		__entry->i_size = i_size;
+		__entry->i_disksize = i_disksize;
+		__entry->new_disksize = new_disksize;
+		__entry->is_disksize_grow = is_disksize_grow;
+	),
+	TP_printk("dev %d:%d ino %llu end %lld i_size %lld i_disksize %lld new_disksize %lld is_disksize_grow %d",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->ino, __entry->end, __entry->i_size,
+		  __entry->i_disksize, __entry->new_disksize,
+		  __entry->is_disksize_grow)
+);
+
+/* Block zero EOF tracepoint */
+TRACE_EVENT(ext4_block_zero_eof,
+	TP_PROTO(struct inode *inode, loff_t from, loff_t length,
+		 bool did_zero, bool zero_written),
+	TP_ARGS(inode, from, length, did_zero, zero_written),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u64, ino)
+		__field(loff_t, from)
+		__field(loff_t, length)
+		__field(loff_t, i_size)
+		__field(loff_t, i_disksize)
+		__field(bool, did_zero)
+		__field(bool, zero_written)
+	),
+	TP_fast_assign(
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->ino = inode->i_ino;
+		__entry->from = from;
+		__entry->length = length;
+		__entry->i_size = inode->i_size;
+		__entry->i_disksize = READ_ONCE(EXT4_I(inode)->i_disksize);
+		__entry->did_zero = did_zero;
+		__entry->zero_written = zero_written;
+	),
+	TP_printk("dev %d:%d ino %llu zero EOF from %lld length %lld i_size %lld i_disksize %lld did_zero %d zero_written %d",
+		  MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino,
+		  __entry->from, __entry->length, __entry->i_size,
+		  __entry->i_disksize, __entry->did_zero, __entry->zero_written)
+);
+
 #endif /* _TRACE_EXT4_H */
 
 /* This part must be outside protection */
-- 
2.52.0