Linux-ext4 Archive on lore.kernel.org
 help / color / Atom feed
From: Eric Biggers <ebiggers@kernel.org>
To: linux-fsdevel@vger.kernel.org
Cc: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	Theodore Ts'o <tytso@mit.edu>, Christoph Hellwig <hch@lst.de>,
	Jan Kara <jack@suse.cz>
Subject: [PATCH v3 02/11] fs: correctly document the inode dirty flags
Date: Tue, 12 Jan 2021 11:02:44 -0800
Message-ID: <20210112190253.64307-3-ebiggers@kernel.org> (raw)
In-Reply-To: <20210112190253.64307-1-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.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
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: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12 19:02 [PATCH v3 00/11] lazytime fix and cleanups Eric Biggers
2021-01-12 19:02 ` [PATCH v3 01/11] fs: fix lazytime expiration handling in __writeback_single_inode() Eric Biggers
2021-01-12 19:02 ` Eric Biggers [this message]
2021-01-12 19:02 ` [PATCH v3 03/11] fs: only specify I_DIRTY_TIME when needed in generic_update_time() Eric Biggers
2021-01-12 19:02 ` [PATCH v3 04/11] fat: only specify I_DIRTY_TIME when needed in fat_update_time() Eric Biggers
2021-01-12 19:02 ` [PATCH v3 05/11] fs: don't call ->dirty_inode for lazytime timestamp updates Eric Biggers
2021-01-12 19:02 ` [PATCH v3 06/11] fs: pass only I_DIRTY_INODE flags to ->dirty_inode Eric Biggers
2021-01-12 19:02 ` [PATCH v3 07/11] fs: clean up __mark_inode_dirty() a bit Eric Biggers
2021-01-12 19:02 ` [PATCH v3 08/11] fs: drop redundant check from __writeback_single_inode() Eric Biggers
2021-01-12 19:02 ` [PATCH v3 09/11] fs: improve comments for writeback_single_inode() Eric Biggers
2021-01-12 19:02 ` [PATCH v3 10/11] gfs2: don't worry about I_DIRTY_TIME in gfs2_fsync() Eric Biggers
2021-01-12 19:02 ` [PATCH v3 11/11] ext4: simplify i_state checks in __ext4_update_other_inode_time() Eric Biggers
2021-01-13  7:07   ` Christoph Hellwig
2021-01-13 16:29 ` [PATCH v3 00/11] lazytime fix and cleanups Jan Kara
2021-01-13 18:49   ` Eric Biggers

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210112190253.64307-3-ebiggers@kernel.org \
    --to=ebiggers@kernel.org \
    --cc=hch@lst.de \
    --cc=jack@suse.cz \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-f2fs-devel@lists.sourceforge.net \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=tytso@mit.edu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ext4 Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-ext4/0 linux-ext4/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ext4 linux-ext4/ https://lore.kernel.org/linux-ext4 \
		linux-ext4@vger.kernel.org
	public-inbox-index linux-ext4

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-ext4


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git