linux-ext4 - [PATCH v3 06/10] ext4: enhance tracepoints during the folios writeback

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Message-ID: <20250701130635.4079595-7-yi.zhang@huaweicloud.com>
Date: Tue,  1 Jul 2025 21:06:31 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ojaswin@...ux.ibm.com,
	sashal@...nel.org,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	libaokun1@...wei.com,
	yukuai3@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH v3 06/10] ext4: enhance tracepoints during the folios writeback

From: Zhang Yi <yi.zhang@...wei.com>

After mpage_map_and_submit_extent() supports restarting handle if
credits are insufficient during allocating blocks, it is more likely to
exit the current mapping iteration and continue to process the current
processing partially mapped folio again. The existing tracepoints are
not sufficient to track this situation, so enhance the tracepoints to
track the writeback position and the return value before and after
submitting the folios.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/inode.c             |  5 ++++-
 include/trace/events/ext4.h | 42 ++++++++++++++++++++++++++++++++-----
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index efe778aaf74b..79389874d35f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2934,7 +2934,8 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
 		}
 		mpd->do_map = 1;
 
-		trace_ext4_da_write_pages(inode, mpd->start_pos, wbc);
+		trace_ext4_da_write_folios_start(inode, mpd->start_pos,
+				mpd->next_pos, wbc);
 		ret = mpage_prepare_extent_to_map(mpd);
 		if (!ret && mpd->map.m_len)
 			ret = mpage_map_and_submit_extent(handle, mpd,
@@ -2972,6 +2973,8 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
 		} else
 			ext4_put_io_end(mpd->io_submit.io_end);
 		mpd->io_submit.io_end = NULL;
+		trace_ext4_da_write_folios_end(inode, mpd->start_pos,
+				mpd->next_pos, wbc, ret);
 
 		if (ret == -ENOSPC && sbi->s_journal) {
 			/*
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 62d52997b5c6..845451077c41 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -482,16 +482,17 @@ TRACE_EVENT(ext4_writepages,
 		  (unsigned long) __entry->writeback_index)
 );
 
-TRACE_EVENT(ext4_da_write_pages,
-	TP_PROTO(struct inode *inode, loff_t start_pos,
+TRACE_EVENT(ext4_da_write_folios_start,
+	TP_PROTO(struct inode *inode, loff_t start_pos, loff_t next_pos,
 		 struct writeback_control *wbc),
 
-	TP_ARGS(inode, start_pos, wbc),
+	TP_ARGS(inode, start_pos, next_pos, wbc),
 
 	TP_STRUCT__entry(
 		__field(	dev_t,	dev			)
 		__field(	ino_t,	ino			)
 		__field(       loff_t,	start_pos		)
+		__field(       loff_t,	next_pos		)
 		__field(	 long,	nr_to_write		)
 		__field(	  int,	sync_mode		)
 	),
@@ -500,16 +501,47 @@ TRACE_EVENT(ext4_da_write_pages,
 		__entry->dev		= inode->i_sb->s_dev;
 		__entry->ino		= inode->i_ino;
 		__entry->start_pos	= start_pos;
+		__entry->next_pos	= next_pos;
 		__entry->nr_to_write	= wbc->nr_to_write;
 		__entry->sync_mode	= wbc->sync_mode;
 	),
 
-	TP_printk("dev %d,%d ino %lu start_pos 0x%llx nr_to_write %ld sync_mode %d",
+	TP_printk("dev %d,%d ino %lu start_pos 0x%llx next_pos 0x%llx nr_to_write %ld sync_mode %d",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
-		  (unsigned long) __entry->ino, __entry->start_pos,
+		  (unsigned long) __entry->ino, __entry->start_pos, __entry->next_pos,
 		  __entry->nr_to_write, __entry->sync_mode)
 );
 
+TRACE_EVENT(ext4_da_write_folios_end,
+	TP_PROTO(struct inode *inode, loff_t start_pos, loff_t next_pos,
+		 struct writeback_control *wbc, int ret),
+
+	TP_ARGS(inode, start_pos, next_pos, wbc, ret),
+
+	TP_STRUCT__entry(
+		__field(	dev_t,	dev			)
+		__field(	ino_t,	ino			)
+		__field(       loff_t,	start_pos		)
+		__field(       loff_t,	next_pos		)
+		__field(	 long,	nr_to_write		)
+		__field(	  int,	ret			)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->start_pos	= start_pos;
+		__entry->next_pos	= next_pos;
+		__entry->nr_to_write	= wbc->nr_to_write;
+		__entry->ret		= ret;
+	),
+
+	TP_printk("dev %d,%d ino %lu start_pos 0x%llx next_pos 0x%llx nr_to_write %ld ret %d",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  (unsigned long) __entry->ino, __entry->start_pos, __entry->next_pos,
+		  __entry->nr_to_write, __entry->ret)
+);
+
 TRACE_EVENT(ext4_da_write_pages_extent,
 	TP_PROTO(struct inode *inode, struct ext4_map_blocks *map),
 
-- 
2.46.1