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 [thread overview]
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
next prev parent reply other threads:[~2021-01-12 19:05 UTC|newest]
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
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