f2fs: fix to flush all dirty inodes during recovery

From: Chao Yu <[email protected]>

generic/417 reported as blow:

------------[ cut here ]------------
kernel BUG at /home/yuchao/git/devf2fs/inode.c:695!
invalid opcode: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 21697 Comm: umount Tainted: G        W  O      4.18.0-rc2+ #39
Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
EIP: f2fs_evict_inode+0x556/0x580 [f2fs]
Call Trace:
 ? _raw_spin_unlock+0x2c/0x50
 evict+0xa8/0x170
 dispose_list+0x34/0x40
 evict_inodes+0x118/0x120
 generic_shutdown_super+0x41/0x100
 ? rcu_read_lock_sched_held+0x97/0xa0
 kill_block_super+0x22/0x50
 kill_f2fs_super+0x6f/0x80 [f2fs]
 deactivate_locked_super+0x3d/0x70
 deactivate_super+0x40/0x60
 cleanup_mnt+0x39/0x70
 __cleanup_mnt+0x10/0x20
 task_work_run+0x81/0xa0
 exit_to_usermode_loop+0x59/0xa7
 do_fast_syscall_32+0x1f5/0x22c
 entry_SYSENTER_32+0x53/0x86
EIP: f2fs_evict_inode+0x556/0x580 [f2fs]

It can simply reproduced with scripts:

1. mkfs.f2fs /dev/zram0
2. mount -t f2fs /dev/zram0 /mnt/f2fs
3. xfs_io -f /mnt/f2fs/file -c "pwrite 0 4k" -c "fsync"
4. godown /mnt/f2fs
5. umount /mnt/f2fs
6. mount -t f2fs -o ro /dev/zram0 /mnt/f2fs
7. umount /mnt/f2fs

The reason is: during recovery, i_{c,m}time of inode will be updated, then the inode can be set dirty w/o being tracked in sbi->inode_list[DIRTY_META] global list, so later write_checkpoint will not flush such dirty inode into node page.

Once umount is called, sync_filesystem() in generic_shutdown_super() will skip sync dirty inodes due to sb_rdonly check, leaving dirty inodes there.

To solve this issue, add sync_inodes_sb() in recovery to make sure all dirty inodes will be flushed before write_checkpoint().

---
 fs/f2fs/recovery.c | 3 +++
 1 file changed, 3 insertions(+)

index 95511ed11a22..7812121ab057 100644
@@ -701,6 +701,9 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
 		struct cp_control cpc = {
 			.reason = CP_RECOVERY,
 		};
+
+		sync_inodes_sb(sbi->sb);
+
 		err = f2fs_write_checkpoint(sbi, &cpc);
 	}
 

2.18.0