f2fs: fix fdatasync
commit
281518c694a5228d6c46fac83529fb3e2c331281 upstream.
For below two cases, we can't guarantee data consistence:
a)
1. xfs_io "pwrite 0
4195328" "fsync"
2. xfs_io "pwrite
4195328 1024" "fdatasync"
3. godown
4. umount & mount
--> isize we updated before fdatasync won't be recovered
b)
1. xfs_io "pwrite -S 0xcc 0
4202496" "fsync"
2. xfs_io "fpunch
4194304 4096" "fdatasync"
3. godown
4. umount & mount
--> dnode we punched before fdatasync won't be recovered
The reason is that normally fdatasync won't be aware of modification
of metadata in file, e.g. isize changing, dnode updating, so in ->fsync
we will skip flushing node pages for above cases, result in making
fdatasynced file being lost during recovery.
Currently we have introduced DIRTY_META global list in sbi for tracking
dirty inode selectively, so in fdatasync we can choose to flush nodes
depend on dirty state of current inode in the list.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>