Re: [PATCH v2 02/12] fs: correctly document the inode dirty flags

Jan Kara
2021-01-11T14:49:39Z

On Fri 08-01-21 23:58:53, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> 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.
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> include/linux/fs.h | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index fd47deea7c176..45a0303b2aeb6 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -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.
> - * I_DIRTY_DATASYNC Data-related inode changes pending. We keep track of
> + * 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
> --
> 2.30.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR