f2fs: support .shutdown in f2fs_sops

Support .shutdown callback in f2fs_sops, then, it can be called to
shut down the file system when underlying block device is marked dead.
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -3497,6 +3497,8 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 struct iattr *attr);
 int f2fs_truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end);
 void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count);
+int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag,
+							bool readonly);
 int f2fs_precache_extents(struct inode *inode);
 int f2fs_fileattr_get(struct dentry *dentry, struct fileattr *fa);
 int f2fs_fileattr_set(struct mnt_idmap *idmap,

fs/f2fs/file.c

@@ -2224,34 +2224,13 @@ static int f2fs_ioc_abort_atomic_write(struct file *filp)
 	return ret;
 }
 
-static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
+int f2fs_do_shutdown(struct f2fs_sb_info *sbi, unsigned int flag,
+							bool readonly)
 {
-	struct inode *inode = file_inode(filp);
-	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct super_block *sb = sbi->sb;
-	__u32 in;
 	int ret = 0;
 
-	if (!capable(CAP_SYS_ADMIN))
-		return -EPERM;
-
-	if (get_user(in, (__u32 __user *)arg))
-		return -EFAULT;
-
-	if (in != F2FS_GOING_DOWN_FULLSYNC) {
-		ret = mnt_want_write_file(filp);
-		if (ret) {
-			if (ret == -EROFS) {
-				ret = 0;
-				f2fs_stop_checkpoint(sbi, false,
-						STOP_CP_REASON_SHUTDOWN);
-				trace_f2fs_shutdown(sbi, in, ret);
-			}
-			return ret;
-		}
-	}
-
-	switch (in) {
+	switch (flag) {
 	case F2FS_GOING_DOWN_FULLSYNC:
 		ret = bdev_freeze(sb->s_bdev);
 		if (ret)
@@ -2290,6 +2269,9 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 		goto out;
 	}
 
+	if (readonly)
+		goto out;
+
 	f2fs_stop_gc_thread(sbi);
 	f2fs_stop_discard_thread(sbi);
 
@@ -2298,10 +2280,44 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 
 	f2fs_update_time(sbi, REQ_TIME);
 out:
-	if (in != F2FS_GOING_DOWN_FULLSYNC)
-		mnt_drop_write_file(filp);
 
-	trace_f2fs_shutdown(sbi, in, ret);
+	trace_f2fs_shutdown(sbi, flag, ret);
+
+	return ret;
+}
+
+static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	__u32 in;
+	int ret;
+	bool need_drop = false, readonly = false;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (get_user(in, (__u32 __user *)arg))
+		return -EFAULT;
+
+	if (in != F2FS_GOING_DOWN_FULLSYNC) {
+		ret = mnt_want_write_file(filp);
+		if (ret) {
+			if (ret != -EROFS)
+				return ret;
+
+			/* fallback to nosync shutdown for readonly fs */
+			in = F2FS_GOING_DOWN_NOSYNC;
+			readonly = true;
+		} else {
+			need_drop = true;
+		}
+	}
+
+	ret = f2fs_do_shutdown(sbi, in, readonly);
+
+	if (need_drop)
+		mnt_drop_write_file(filp);
 
 	return ret;
 }

fs/f2fs/super.c

@@ -2547,6 +2547,11 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	return err;
 }
 
+static void f2fs_shutdown(struct super_block *sb)
+{
+	f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false);
+}
+
 #ifdef CONFIG_QUOTA
 static bool f2fs_need_recovery(struct f2fs_sb_info *sbi)
 {
@@ -3146,6 +3151,7 @@ static const struct super_operations f2fs_sops = {
 	.unfreeze_fs	= f2fs_unfreeze,
 	.statfs		= f2fs_statfs,
 	.remount_fs	= f2fs_remount,
+	.shutdown	= f2fs_shutdown,
 };
 
 #ifdef CONFIG_FS_ENCRYPTION