f2fs: support FAULT_TIMEOUT

Support to inject a timeout fault into function, currently it only
support to inject timeout to commit_atomic_write flow to reproduce
inconsistent bug, like the bug fixed by commit f098aeb ("f2fs:
fix to avoid atomicity corruption of atomic file").

By default, the new type fault will inject 1000ms timeout, and the
timeout process can be interrupted by SIGKILL.

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -735,6 +735,7 @@ Description:	Support configuring fault injection type, should be
 		FAULT_BLKADDR_CONSISTENCE        0x000080000
 		FAULT_NO_SEGMENT                 0x000100000
 		FAULT_INCONSISTENT_FOOTER        0x000200000
+		FAULT_TIMEOUT                    0x000400000 (1000ms)
 		===========================      ===========
 
 What:		/sys/fs/f2fs/<disk>/discard_io_aware_gran

Documentation/filesystems/f2fs.rst

@@ -207,6 +207,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_BLKADDR_CONSISTENCE        0x000080000
 			 FAULT_NO_SEGMENT                 0x000100000
 			 FAULT_INCONSISTENT_FOOTER        0x000200000
+			 FAULT_TIMEOUT                    0x000400000 (1000ms)
 			 ===========================      ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random

fs/f2fs/f2fs.h

@@ -63,6 +63,7 @@ enum {
 	FAULT_BLKADDR_CONSISTENCE,
 	FAULT_NO_SEGMENT,
 	FAULT_INCONSISTENT_FOOTER,
+	FAULT_TIMEOUT,
 	FAULT_MAX,
 };
 
@@ -613,6 +614,9 @@ enum {
 /* congestion wait timeout value, default: 20ms */
 #define	DEFAULT_IO_TIMEOUT	(msecs_to_jiffies(20))
 
+/* timeout value injected, default: 1000ms */
+#define DEFAULT_FAULT_TIMEOUT	(msecs_to_jiffies(1000))
+
 /* maximum retry quota flush count */
 #define DEFAULT_RETRY_QUOTA_FLUSH_COUNT		8
 
@@ -4815,6 +4819,19 @@ static inline void f2fs_io_schedule_timeout(long timeout)
 	io_schedule_timeout(timeout);
 }
 
+static inline void f2fs_io_schedule_timeout_killable(long timeout)
+{
+	while (timeout) {
+		if (fatal_signal_pending(current))
+			return;
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		io_schedule_timeout(DEFAULT_IO_TIMEOUT);
+		if (timeout <= DEFAULT_IO_TIMEOUT)
+			return;
+		timeout -= DEFAULT_IO_TIMEOUT;
+	}
+}
+
 static inline void f2fs_handle_page_eio(struct f2fs_sb_info *sbi,
 				struct folio *folio, enum page_type type)
 {

fs/f2fs/segment.c

@@ -371,6 +371,9 @@ static int __f2fs_commit_atomic_write(struct inode *inode)
 	}
 
 out:
+	if (time_to_inject(sbi, FAULT_TIMEOUT))
+		f2fs_io_schedule_timeout_killable(DEFAULT_FAULT_TIMEOUT);
+
 	if (ret) {
 		sbi->revoked_atomic_block += fi->atomic_write_cnt;
 	} else {

fs/f2fs/super.c

@@ -65,6 +65,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_BLKADDR_CONSISTENCE]	= "inconsistent blkaddr",
 	[FAULT_NO_SEGMENT]		= "no free segment",
 	[FAULT_INCONSISTENT_FOOTER]	= "inconsistent footer",
+	[FAULT_TIMEOUT]			= "timeout",
 };
 
 int f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned long rate,