Man page 9 : __mark_inode_dirty

__mark_inode_dirty - internal function

void __mark_inode_dirty(struct inode *  inode , int  flags );

inode
    inode to mark

flags
    what kind of dirty (i.e. I_DIRTY_SYNC) Mark an inode as dirty. Callers should use mark_inode_dirty or mark_inode_dirty_sync.

Put the inode on the super blockAqs dirty list.

CAREFUL! We mark it dirty unconditionally, but move it onto the dirty list only if it is hashed or if it refers to a blockdev. If it was not hashed, it will never be added to the dirty list even if it is later hashed, as it will have been marked dirty already.

In short, make sure you hash any inodes _before_ you start marking them dirty.

Note that for blockdevs, inode->dirtied_when represents the dirtying time of the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of the kernel-internal blockdev inode represents the dirtying time of the blockdevAqs pages. This is why for I_DIRTY_PAGES we always use page->mapping->host, so the page-dirtying time is recorded in the internal blockdev inode.