f2fs: support errors=remount-ro|continue|panic mountoption

This patch supports errors=remount-ro|continue|panic mount option
for f2fs.

f2fs behaves as below in three different modes:
mode			continue	remount-ro	panic
access ops		normal		noraml		N/A
syscall errors		-EIO		-EROFS		N/A
mount option		rw		ro		N/A
pending dir write	keep		keep		N/A
pending non-dir write	drop		keep		N/A
pending node write	drop		keep		N/A
pending meta write	keep		keep		N/A

By default it uses "continue" mode.

[Yangtao helps to clean up function's name]
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/filesystems/f2fs.rst

@@ -351,6 +351,22 @@ age_extent_cache	 Enable an age extent cache based on rb-tree. It records
 			 data block update frequency of the extent per inode, in
 			 order to provide better temperature hints for data block
 			 allocation.
+errors=%s		 Specify f2fs behavior on critical errors. This supports modes:
+			 "panic", "continue" and "remount-ro", respectively, trigger
+			 panic immediately, continue without doing anything, and remount
+			 the partition in read-only mode. By default it uses "continue"
+			 mode.
+			 ====================== =============== =============== ========
+			 mode			continue	remount-ro	panic
+			 ====================== =============== =============== ========
+			 access ops		normal		noraml		N/A
+			 syscall errors		-EIO		-EROFS		N/A
+			 mount option		rw		ro		N/A
+			 pending dir write	keep		keep		N/A
+			 pending non-dir write	drop		keep		N/A
+			 pending node write	drop		keep		N/A
+			 pending meta write	keep		keep		N/A
+			 ====================== =============== =============== ========
 ======================== ============================================================
 
 Debugfs Entries

fs/f2fs/checkpoint.c

@@ -30,12 +30,9 @@ void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io,
 						unsigned char reason)
 {
 	f2fs_build_fault_attr(sbi, 0, 0);
-	set_ckpt_flags(sbi, CP_ERROR_FLAG);
+	if (!end_io)
-	if (!end_io) {
 		f2fs_flush_merged_writes(sbi);
-
+	f2fs_handle_critical_error(sbi, reason, end_io);
-		f2fs_handle_stop(sbi, reason);
-	}
 }
 
 /*

fs/f2fs/data.c

@@ -2807,6 +2807,10 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 		if (S_ISDIR(inode->i_mode) &&
 				!is_sbi_flag_set(sbi, SBI_IS_CLOSE))
 			goto redirty_out;
+
+		/* keep data pages in remount-ro mode */
+		if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_READONLY)
+			goto redirty_out;
 		goto out;
 	}
 

fs/f2fs/f2fs.h

@@ -162,6 +162,7 @@ struct f2fs_mount_info {
 	int fs_mode;			/* fs mode: LFS or ADAPTIVE */
 	int bggc_mode;			/* bggc mode: off, on or sync */
 	int memory_mode;		/* memory mode */
+	int errors;			/* errors parameter */
 	int discard_unit;		/*
 					 * discard command's offset/size should
 					 * be aligned to this unit: block,
@@ -1370,6 +1371,12 @@ enum {
 	MEMORY_MODE_LOW,	/* memory mode for low memry devices */
 };
 
+enum errors_option {
+	MOUNT_ERRORS_READONLY,	/* remount fs ro on errors */
+	MOUNT_ERRORS_CONTINUE,	/* continue on errors */
+	MOUNT_ERRORS_PANIC,	/* panic on errors */
+};
+
 static inline int f2fs_test_bit(unsigned int nr, char *addr);
 static inline void f2fs_set_bit(unsigned int nr, char *addr);
 static inline void f2fs_clear_bit(unsigned int nr, char *addr);
@@ -1721,8 +1728,14 @@ struct f2fs_sb_info {
 
 	struct workqueue_struct *post_read_wq;	/* post read workqueue */
 
-	unsigned char errors[MAX_F2FS_ERRORS];	/* error flags */
+	/*
-	spinlock_t error_lock;			/* protect errors array */
+	 * If we are in irq context, let's update error information into
+	 * on-disk superblock in the work.
+	 */
+	struct work_struct s_error_work;
+	unsigned char errors[MAX_F2FS_ERRORS];		/* error flags */
+	unsigned char stop_reason[MAX_STOP_REASON];	/* stop reason */
+	spinlock_t error_lock;			/* protect errors/stop_reason array */
 	bool error_dirty;			/* errors of sb is dirty */
 
 	struct kmem_cache *inline_xattr_slab;	/* inline xattr entry */
@@ -3541,8 +3554,9 @@ int f2fs_enable_quota_files(struct f2fs_sb_info *sbi, bool rdonly);
 int f2fs_quota_sync(struct super_block *sb, int type);
 loff_t max_file_blocks(struct inode *inode);
 void f2fs_quota_off_umount(struct super_block *sb);
-void f2fs_handle_stop(struct f2fs_sb_info *sbi, unsigned char reason);
 void f2fs_save_errors(struct f2fs_sb_info *sbi, unsigned char flag);
+void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason,
+							bool irq_context);
 void f2fs_handle_error(struct f2fs_sb_info *sbi, unsigned char error);
 int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover);
 int f2fs_sync_fs(struct super_block *sb, int sync);

fs/f2fs/file.c

@@ -2225,7 +2225,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 				ret = 0;
 				f2fs_stop_checkpoint(sbi, false,
 						STOP_CP_REASON_SHUTDOWN);
-				set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
 				trace_f2fs_shutdown(sbi, in, ret);
 			}
 			return ret;
@@ -2238,7 +2237,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 		if (ret)
 			goto out;
 		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_SHUTDOWN);
-		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
 		thaw_bdev(sb->s_bdev);
 		break;
 	case F2FS_GOING_DOWN_METASYNC:
@@ -2247,16 +2245,13 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 		if (ret)
 			goto out;
 		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_SHUTDOWN);
-		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
 		break;
 	case F2FS_GOING_DOWN_NOSYNC:
 		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_SHUTDOWN);
-		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
 		break;
 	case F2FS_GOING_DOWN_METAFLUSH:
 		f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_META_IO);
 		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_SHUTDOWN);
-		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
 		break;
 	case F2FS_GOING_DOWN_NEED_FSCK:
 		set_sbi_flag(sbi, SBI_NEED_FSCK);

fs/f2fs/gc.c

@@ -59,7 +59,7 @@ static int gc_thread_func(void *data)
 		if (gc_th->gc_wake)
 			gc_th->gc_wake = false;
 
-		if (try_to_freeze()) {
+		if (try_to_freeze() || f2fs_readonly(sbi->sb)) {
 			stat_other_skip_bggc_count(sbi);
 			continue;
 		}

fs/f2fs/node.c

@@ -1596,6 +1596,9 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
 	trace_f2fs_writepage(page, NODE);
 
 	if (unlikely(f2fs_cp_error(sbi))) {
+		/* keep node pages in remount-ro mode */
+		if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_READONLY)
+			goto redirty_out;
 		ClearPageUptodate(page);
 		dec_page_count(sbi, F2FS_DIRTY_NODES);
 		unlock_page(page);

fs/f2fs/super.c

@@ -164,6 +164,7 @@ enum {
 	Opt_discard_unit,
 	Opt_memory_mode,
 	Opt_age_extent_cache,
+	Opt_errors,
 	Opt_err,
 };
 
@@ -243,6 +244,7 @@ static match_table_t f2fs_tokens = {
 	{Opt_discard_unit, "discard_unit=%s"},
 	{Opt_memory_mode, "memory=%s"},
 	{Opt_age_extent_cache, "age_extent_cache"},
+	{Opt_errors, "errors=%s"},
 	{Opt_err, NULL},
 };
 
@@ -1268,6 +1270,25 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
 		case Opt_age_extent_cache:
 			set_opt(sbi, AGE_EXTENT_CACHE);
 			break;
+		case Opt_errors:
+			name = match_strdup(&args[0]);
+			if (!name)
+				return -ENOMEM;
+			if (!strcmp(name, "remount-ro")) {
+				F2FS_OPTION(sbi).errors =
+						MOUNT_ERRORS_READONLY;
+			} else if (!strcmp(name, "continue")) {
+				F2FS_OPTION(sbi).errors =
+						MOUNT_ERRORS_CONTINUE;
+			} else if (!strcmp(name, "panic")) {
+				F2FS_OPTION(sbi).errors =
+						MOUNT_ERRORS_PANIC;
+			} else {
+				kfree(name);
+				return -EINVAL;
+			}
+			kfree(name);
+			break;
 		default:
 			f2fs_err(sbi, "Unrecognized mount option \"%s\" or missing value",
 				 p);
@@ -1622,6 +1643,9 @@ static void f2fs_put_super(struct super_block *sb)
 	f2fs_destroy_node_manager(sbi);
 	f2fs_destroy_segment_manager(sbi);
 
+	/* flush s_error_work before sbi destroy */
+	flush_work(&sbi->s_error_work);
+
 	f2fs_destroy_post_read_wq(sbi);
 
 	kvfree(sbi->ckpt);
@@ -2052,6 +2076,13 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 	else if (F2FS_OPTION(sbi).memory_mode == MEMORY_MODE_LOW)
 		seq_printf(seq, ",memory=%s", "low");
 
+	if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_READONLY)
+		seq_printf(seq, ",errors=%s", "remount-ro");
+	else if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_CONTINUE)
+		seq_printf(seq, ",errors=%s", "continue");
+	else if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_PANIC)
+		seq_printf(seq, ",errors=%s", "panic");
+
 	return 0;
 }
 
@@ -2080,6 +2111,7 @@ static void default_options(struct f2fs_sb_info *sbi)
 	}
 	F2FS_OPTION(sbi).bggc_mode = BGGC_MODE_ON;
 	F2FS_OPTION(sbi).memory_mode = MEMORY_MODE_NORMAL;
+	F2FS_OPTION(sbi).errors = MOUNT_ERRORS_CONTINUE;
 
 	sbi->sb->s_flags &= ~SB_INLINECRYPT;
 
@@ -2281,6 +2313,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	if (err)
 		goto restore_opts;
 
+	/* flush outstanding errors before changing fs state */
+	flush_work(&sbi->s_error_work);
+
 	/*
 	 * Previous and new state of filesystem is RO,
 	 * so skip checking GC and FLUSH_MERGE conditions.
@@ -3926,45 +3961,60 @@ int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover)
 	return err;
 }
 
-void f2fs_handle_stop(struct f2fs_sb_info *sbi, unsigned char reason)
+static void save_stop_reason(struct f2fs_sb_info *sbi, unsigned char reason)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sbi->error_lock, flags);
+	if (sbi->stop_reason[reason] < GENMASK(BITS_PER_BYTE - 1, 0))
+		sbi->stop_reason[reason]++;
+	spin_unlock_irqrestore(&sbi->error_lock, flags);
+}
+
+static void f2fs_record_stop_reason(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
+	unsigned long flags;
 	int err;
 
 	f2fs_down_write(&sbi->sb_lock);
 
-	if (raw_super->s_stop_reason[reason] < GENMASK(BITS_PER_BYTE - 1, 0))
+	spin_lock_irqsave(&sbi->error_lock, flags);
-		raw_super->s_stop_reason[reason]++;
+	memcpy(raw_super->s_stop_reason, sbi->stop_reason, MAX_STOP_REASON);
+	spin_unlock_irqrestore(&sbi->error_lock, flags);
 
 	err = f2fs_commit_super(sbi, false);
-	if (err)
+
-		f2fs_err(sbi, "f2fs_commit_super fails to record reason:%u err:%d",
-								reason, err);
 	f2fs_up_write(&sbi->sb_lock);
+	if (err)
+		f2fs_err(sbi, "f2fs_commit_super fails to record err:%d", err);
 }
 
 void f2fs_save_errors(struct f2fs_sb_info *sbi, unsigned char flag)
 {
-	spin_lock(&sbi->error_lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&sbi->error_lock, flags);
 	if (!test_bit(flag, (unsigned long *)sbi->errors)) {
 		set_bit(flag, (unsigned long *)sbi->errors);
 		sbi->error_dirty = true;
 	}
-	spin_unlock(&sbi->error_lock);
+	spin_unlock_irqrestore(&sbi->error_lock, flags);
 }
 
 static bool f2fs_update_errors(struct f2fs_sb_info *sbi)
 {
+	unsigned long flags;
 	bool need_update = false;
 
-	spin_lock(&sbi->error_lock);
+	spin_lock_irqsave(&sbi->error_lock, flags);
 	if (sbi->error_dirty) {
 		memcpy(F2FS_RAW_SUPER(sbi)->s_errors, sbi->errors,
 							MAX_F2FS_ERRORS);
 		sbi->error_dirty = false;
 		need_update = true;
 	}
-	spin_unlock(&sbi->error_lock);
+	spin_unlock_irqrestore(&sbi->error_lock, flags);
 
 	return need_update;
 }
@@ -3988,6 +4038,66 @@ void f2fs_handle_error(struct f2fs_sb_info *sbi, unsigned char error)
 	f2fs_up_write(&sbi->sb_lock);
 }
 
+static bool system_going_down(void)
+{
+	return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
+		|| system_state == SYSTEM_RESTART;
+}
+
+void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason,
+							bool irq_context)
+{
+	struct super_block *sb = sbi->sb;
+	bool shutdown = reason == STOP_CP_REASON_SHUTDOWN;
+	bool continue_fs = !shutdown &&
+			F2FS_OPTION(sbi).errors == MOUNT_ERRORS_CONTINUE;
+
+	set_ckpt_flags(sbi, CP_ERROR_FLAG);
+
+	if (!f2fs_hw_is_readonly(sbi)) {
+		save_stop_reason(sbi, reason);
+
+		if (irq_context && !shutdown)
+			schedule_work(&sbi->s_error_work);
+		else
+			f2fs_record_stop_reason(sbi);
+	}
+
+	/*
+	 * We force ERRORS_RO behavior when system is rebooting. Otherwise we
+	 * could panic during 'reboot -f' as the underlying device got already
+	 * disabled.
+	 */
+	if (F2FS_OPTION(sbi).errors == MOUNT_ERRORS_PANIC &&
+				!shutdown && !system_going_down() &&
+				!is_sbi_flag_set(sbi, SBI_IS_SHUTDOWN))
+		panic("F2FS-fs (device %s): panic forced after error\n",
+							sb->s_id);
+
+	if (shutdown)
+		set_sbi_flag(sbi, SBI_IS_SHUTDOWN);
+
+	/* continue filesystem operators if errors=continue */
+	if (continue_fs || f2fs_readonly(sb))
+		return;
+
+	f2fs_warn(sbi, "Remounting filesystem read-only");
+	/*
+	 * Make sure updated value of ->s_mount_flags will be visible before
+	 * ->s_flags update
+	 */
+	smp_wmb();
+	sb->s_flags |= SB_RDONLY;
+}
+
+static void f2fs_record_error_work(struct work_struct *work)
+{
+	struct f2fs_sb_info *sbi = container_of(work,
+					struct f2fs_sb_info, s_error_work);
+
+	f2fs_record_stop_reason(sbi);
+}
+
 static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
@@ -4218,7 +4328,9 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_fs_info = sbi;
 	sbi->raw_super = raw_super;
 
+	INIT_WORK(&sbi->s_error_work, f2fs_record_error_work);
 	memcpy(sbi->errors, raw_super->s_errors, MAX_F2FS_ERRORS);
+	memcpy(sbi->stop_reason, raw_super->s_stop_reason, MAX_STOP_REASON);
 
 	/* precompute checksum seed for metadata */
 	if (f2fs_sb_has_inode_chksum(sbi))
@@ -4615,6 +4727,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	f2fs_destroy_segment_manager(sbi);
 stop_ckpt_thread:
 	f2fs_stop_ckpt_thread(sbi);
+	/* flush s_error_work before sbi destroy */
+	flush_work(&sbi->s_error_work);
 	f2fs_destroy_post_read_wq(sbi);
 free_devices:
 	destroy_device_list(sbi);