Unverified Commit 2ed81b4b authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Christian Brauner
Browse files

fs: make plain ->i_state access fail to compile 



... 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: default avatarMateusz Guzik <mjguzik@gmail.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 18c61399

include/linux/fs.h

+14 −7
Original line number Diff line number Diff line
@@ -785,6 +785,13 @@ 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
@@ -843,7 +850,7 @@ 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;
@@ -909,19 +916,19 @@ 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_set_raw(struct inode *inode,

				       enum inode_state_flags_enum flags)

{

	WRITE_ONCE(inode->i_state, inode->i_state | flags);

	WRITE_ONCE(inode->i_state.__state, inode->i_state.__state | flags);

}



static inline void inode_state_set(struct inode *inode,
@@ -934,7 +941,7 @@ static inline void inode_state_set(struct inode *inode, 
static inline void inode_state_clear_raw(struct inode *inode,

					 enum inode_state_flags_enum flags)

{

	WRITE_ONCE(inode->i_state, inode->i_state & ~flags);

	WRITE_ONCE(inode->i_state.__state, inode->i_state.__state & ~flags);

}



static inline void inode_state_clear(struct inode *inode,
@@ -947,7 +954,7 @@ static inline void inode_state_clear(struct inode *inode, 
static inline void inode_state_assign_raw(struct inode *inode,

					  enum inode_state_flags_enum flags)

{

	WRITE_ONCE(inode->i_state, flags);

	WRITE_ONCE(inode->i_state.__state, flags);

}



static inline void inode_state_assign(struct inode *inode,
@@ -962,7 +969,7 @@ static inline void inode_state_replace_raw(struct inode *inode, 
					   enum inode_state_flags_enum setflags)

{

	enum inode_state_flags_enum flags;

	flags = inode->i_state;

	flags = inode->i_state.__state;

	flags &= ~clearflags;

	flags |= setflags;

	inode_state_assign_raw(inode, flags);