This is a note to let you know that I've just added the patch titled
fs: correctly document the inode dirty flags
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-correctly-document-the-inode-dirty-flags.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5aa02147cd3d8e2a637fb16a091ff7e784f74ecd
Author: Eric Biggers <ebiggers@xxxxxxxxxx>
Date: Tue Jan 12 11:02:44 2021 -0800
fs: correctly document the inode dirty flags
[ Upstream commit 1e9d63331f8fa556f31e1406ab12f2a1e5cdb495 ]
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.
Link: https://lore.kernel.org/r/20210112190253.64307-3-ebiggers@xxxxxxxxxx
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Stable-dep-of: cbfecb927f42 ("fs: record I_DIRTY_TIME even if inode already has I_DIRTY_INODE")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c8f887641878..8ee26322a527 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2087,8 +2087,8 @@ 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
@@ -2097,12 +2097,20 @@ 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
