--------------------------- dentry_operations --------------------------
prototypes:
int (*d_revalidate)(struct dentry *, unsigned int);
+ int (*d_weak_revalidate)(struct dentry *, unsigned int);
int (*d_hash)(const struct dentry *, const struct inode *,
struct qstr *);
int (*d_compare)(const struct dentry *, const struct inode *,
locking rules:
rename_lock ->d_lock may block rcu-walk
d_revalidate: no no yes (ref-walk) maybe
+d_weak_revalidate:no no yes no
d_hash no no no maybe
d_compare: yes no no maybe
d_delete: no yes no no
readlink: no
follow_link: no
put_link: no
-truncate: yes (see below)
setattr: yes
permission: no (may not block if called in rcu-walk mode)
get_acl: no
Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
victim.
cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem.
- ->truncate() is never called directly - it's a callback, not a
-method. It's called by vmtruncate() - deprecated library function used by
-->setattr(). Locking information above applies to that call (i.e. is
-inherited from ->setattr() - vmtruncate() is used when ATTR_SIZE had been
-passed).
See Documentation/filesystems/directory-locking for more detailed discussion
of the locking scheme for directory operations.