diff mbox series

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

Message ID 20210109075903.208222-3-ebiggers@kernel.org (mailing list archive)
State Superseded, archived
Headers show
Series lazytime fix and cleanups | expand

Commit Message

Eric Biggers Jan. 9, 2021, 7:58 a.m. UTC 
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>
---
 include/linux/fs.h | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

Comments

Jan Kara Jan. 11, 2021, 2:48 p.m. UTC | #1 
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
>
diff mbox series

Patch

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