--------------------------- dquot_operations -------------------------------
prototypes:
int (*initialize) (struct inode *, int);
- int (*drop) (struct inode *);
int (*write_dquot) (struct dquot *);
int (*acquire_dquot) (struct dquot *);
int (*release_dquot) (struct dquot *);
FS recursion Held locks when called
initialize: yes maybe dqonoff_sem
-drop: yes -
write_dquot: yes dqonoff_sem or dqptr_sem
acquire_dquot: yes dqonoff_sem or dqptr_sem
release_dquot: yes dqonoff_sem or dqptr_sem