[PATCH] f2fs: support fault injection for flush submission error

[Yangtao Li <frank.li@vivo.com>]

This patch supports to inject fault into __submit_flush_wait() to
simulate flush cmd io error.

Usage:
a) echo 524288 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=524288 <dev> <mountpoint>

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 Documentation/filesystems/f2fs.rst |  1 +
 fs/f2fs/f2fs.h                     |  1 +
 fs/f2fs/segment.c                  | 12 +++++++++++-
 fs/f2fs/super.c                    |  1 +
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index 6e67c5e6c7c3..316d153cc5fb 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -202,6 +202,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_DQUOT_INIT	  0x000010000
 			 FAULT_LOCK_OP		  0x000020000
 			 FAULT_BLKADDR		  0x000040000
+			 FAULT_FLUSH		  0x000080000
 			 ===================	  ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 04ef4cce3d7f..832baf08ecac 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -61,6 +61,7 @@ enum {
 	FAULT_DQUOT_INIT,
 	FAULT_LOCK_OP,
 	FAULT_BLKADDR,
+	FAULT_FLUSH,
 	FAULT_MAX,
 };
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index aa4be7f25963..61c650db7627 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -486,7 +486,17 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi, bool from_bg)
 static int __submit_flush_wait(struct f2fs_sb_info *sbi,
 				struct block_device *bdev)
 {
-	int ret = blkdev_issue_flush(bdev);
+	int ret;
+
+	if (time_to_inject(sbi, FAULT_FLUSH)) {
+		f2fs_show_injection_info(sbi, FAULT_FLUSH);
+		ret = -EIO;
+		goto submit;
+	}
+
+	ret = blkdev_issue_flush(bdev);
+
+submit:
 
 	trace_f2fs_issue_flush(bdev, test_opt(sbi, NOBARRIER),
 				test_opt(sbi, FLUSH_MERGE), ret);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index a43d8a46a6e5..3d3d22ac527b 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -62,6 +62,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_DQUOT_INIT]	= "dquot initialize",
 	[FAULT_LOCK_OP]		= "lock_op",
 	[FAULT_BLKADDR]		= "invalid blkaddr",
+	[FAULT_FLUSH]		= "flush error",
 };
 
 void f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned int rate,
-- 
2.25.1