2 To handle sys_sync, we want to schedule writes for all data blocks,
3 then trigger a checkpoint. This will force all inode metadata out.
5 By contrast, fsync just writes the inode without a checkpoint by
6 doing an update for the metadata in the inode.
8 For a sys_sync, we want to avoid all the inode syncs.
13 This writes all the data blocks
17 __writeback_single_inode
33 sync_filesystems(wait)
37 So write_inode is called from
39 __sync_single_inode(wbc)
41 __writeback_single_inode(wbc)
44 writeback_inodes(wbc) - for all filesystems
45 balance_dirty_pages - WB_SYNC_NONE
46 background_writeout NONE
48 sync_inodes_sb(sb, wait) - for one filesystem
58 generic_osync_inode - sets wait.