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From: Eric Biggers <ebiggers@kernel.org>
To: linux-fsdevel@vger.kernel.org
Cc: linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-xfs@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
	Christoph Hellwig <hch@lst.de>
Subject: [PATCH 07/13] fs: correctly document the inode dirty flags
Date: Mon,  4 Jan 2021 16:54:46 -0800
Message-ID: <20210105005452.92521-8-ebiggers@kernel.org> (raw)
In-Reply-To: <20210105005452.92521-1-ebiggers@kernel.org>

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.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 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


  parent reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05  0:54 [PATCH 00/13] lazytime fixes and cleanups Eric Biggers
2021-01-05  0:54 ` [PATCH 01/13] fs: avoid double-writing inodes on lazytime expiration Eric Biggers
2021-01-07 14:47   ` Jan Kara
2021-01-07 14:58     ` Matthew Wilcox
2021-01-07 21:46     ` Eric Biggers
2021-01-08  8:54       ` Christoph Hellwig
2021-01-08  9:01     ` Christoph Hellwig
2021-01-09 17:11       ` Eric Biggers
2021-01-05  0:54 ` [PATCH 02/13] gfs2: don't worry about I_DIRTY_TIME in gfs2_fsync() Eric Biggers
2021-01-08  8:54   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 03/13] fs: only specify I_DIRTY_TIME when needed in generic_update_time() Eric Biggers
2021-01-08  8:57   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 04/13] fat: only specify I_DIRTY_TIME when needed in fat_update_time() Eric Biggers
2021-01-07 13:13   ` Jan Kara
2021-01-07 19:10     ` Eric Biggers
2021-01-05  0:54 ` [PATCH 05/13] fs: don't call ->dirty_inode for lazytime timestamp updates Eric Biggers
2021-01-07 13:17   ` Jan Kara
2021-01-07 13:18     ` Jan Kara
2021-01-08  9:02   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 06/13] fs: pass only I_DIRTY_INODE flags to ->dirty_inode Eric Biggers
2021-01-08  9:02   ` Christoph Hellwig
2021-01-05  0:54 ` Eric Biggers [this message]
2021-01-08  9:03   ` [PATCH 07/13] fs: correctly document the inode dirty flags Christoph Hellwig
2021-01-05  0:54 ` [PATCH 08/13] ext4: simplify i_state checks in __ext4_update_other_inode_time() Eric Biggers
2021-01-07 13:24   ` Jan Kara
2021-01-07 19:06     ` Eric Biggers
2021-01-05  0:54 ` [PATCH 09/13] fs: drop redundant checks from __writeback_single_inode() Eric Biggers
2021-01-08  9:12   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 10/13] fs: clean up __mark_inode_dirty() a bit Eric Biggers
2021-01-08  9:10   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 11/13] fs: add a lazytime_expired method Eric Biggers
2021-01-07 14:02   ` Jan Kara
2021-01-07 22:05     ` Eric Biggers
2021-01-08  9:14       ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 12/13] xfs: remove a stale comment from xfs_file_aio_write_checks() Eric Biggers
2021-01-08  9:15   ` Christoph Hellwig
2021-01-05  0:54 ` [PATCH 13/13] xfs: implement lazytime_expired Eric Biggers

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