... to make sure all accesses are properly validated. Merely renaming the var to __i_state still lets the compiler make the following suggestion: error: 'struct inode' has no member named 'i_state'; did you mean '__i_state'? Unfortunately some people will add the __'s and call it a day. In order to make it harder to mess up in this way, hide it behind a struct. The resulting error message should be convincing in terms of checking what to do: error: invalid operands to binary & (have 'struct inode_state_flags' and 'int') Of course people determined to do a plain access can still do it, but nothing can be done for that case. Signed-off-by: Mateusz Guzik --- include/linux/fs.h | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 11eef4ef5ace..80c53af7bc5a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -782,6 +782,13 @@ enum inode_state_flags_enum { #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES) #define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME) +/* + * Use inode_state_read() & friends to access. + */ +struct inode_state_flags { + enum inode_state_flags_enum __state; +}; + /* * Keep mostly read-only and often accessed (especially for * the RCU path lookup and 'stat' data) fields at the beginning @@ -840,7 +847,7 @@ struct inode { #endif /* Misc */ - enum inode_state_flags_enum i_state; + struct inode_state_flags i_state; /* 32-bit hole */ struct rw_semaphore i_rwsem; @@ -906,19 +913,19 @@ struct inode { */ static inline enum inode_state_flags_enum inode_state_read_once(struct inode *inode) { - return READ_ONCE(inode->i_state); + return READ_ONCE(inode->i_state.__state); } static inline enum inode_state_flags_enum inode_state_read(struct inode *inode) { lockdep_assert_held(&inode->i_lock); - return inode->i_state; + return inode->i_state.__state; } static inline void inode_state_add_raw(struct inode *inode, enum inode_state_flags_enum addflags) { - WRITE_ONCE(inode->i_state, inode->i_state | addflags); + WRITE_ONCE(inode->i_state.__state, inode->i_state.__state | addflags); } static inline void inode_state_add(struct inode *inode, @@ -931,7 +938,7 @@ static inline void inode_state_add(struct inode *inode, static inline void inode_state_del_raw(struct inode *inode, enum inode_state_flags_enum delflags) { - WRITE_ONCE(inode->i_state, inode->i_state & ~delflags); + WRITE_ONCE(inode->i_state.__state, inode->i_state.__state & ~delflags); } static inline void inode_state_del(struct inode *inode, @@ -944,7 +951,7 @@ static inline void inode_state_del(struct inode *inode, static inline void inode_state_set_raw(struct inode *inode, enum inode_state_flags_enum setflags) { - WRITE_ONCE(inode->i_state, setflags); + WRITE_ONCE(inode->i_state.__state, setflags); } static inline void inode_state_set(struct inode *inode, -- 2.43.0