Commit 1e9d6333 authored by Eric Biggers's avatar Eric Biggers Committed by Jan Kara
Browse files

fs: correctly document the inode dirty flags 

The documentation for I_DIRTY_SYNC and I_DIRTY_DATASYNC is a bit
misleading, and I_DIRTY_TIME isn't documented at all.  Fix this.

Link: https://lore.kernel.org/r/20210112190253.64307-3-ebiggers@kernel.org


Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 1e249cb5

include/linux/fs.h

+13 −5
Original line number Diff line number Diff line
@@ -2084,8 +2084,8 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src, 
/*

 * Inode state bits.  Protected by inode->i_lock

 *

 * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,

 * I_DIRTY_DATASYNC and I_DIRTY_PAGES.

 * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,

 * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.

 *

 * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,

 * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
@@ -2094,12 +2094,20 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src, 
 * Two bits are used for locking and completion notification, I_NEW and I_SYNC.

 *

 * I_DIRTY_SYNC		Inode is dirty, but doesn't have to be written on

 *			fdatasync().  i_atime is the usual cause.

 *			fdatasync() (unless I_DIRTY_DATASYNC is also set).

 *			Timestamp updates are the usual cause.

 * I_DIRTY_DATASYNC	Data-related inode changes pending.  We keep track of

 *			these changes separately from I_DIRTY_SYNC so that we

 *			don't have to write inode on fdatasync() when only

 *			mtime has changed in it.

 *			e.g. the timestamps have changed.

 * I_DIRTY_PAGES	Inode has dirty pages.  Inode itself may be clean.

 * I_DIRTY_TIME		The inode itself only has dirty timestamps, and the

 *			lazytime mount option is enabled.  We keep track of this

 *			separately from I_DIRTY_SYNC in order to implement

 *			lazytime.  This gets cleared if I_DIRTY_INODE

 *			(I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set.  I.e.

 *			either I_DIRTY_TIME *or* I_DIRTY_INODE can be set in

 *			i_state, but not both.  I_DIRTY_PAGES may still be set.

 * I_NEW		Serves as both a mutex and completion notification.

 *			New inodes set I_NEW.  If two processes both create

 *			the same inode, one of them will release its inode and