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authorEric Biggers <ebiggers@google.com>2021-01-12 22:02:44 +0300
committerJan Kara <jack@suse.cz>2021-01-13 19:26:23 +0300
commit1e9d63331f8fa556f31e1406ab12f2a1e5cdb495 (patch)
treed53b98b13c9479de78c1726dc4e74a13713edd7b /include/linux/fs.h
parent1e249cb5b7fc09ff216aa5a12f6c302e434e88f9 (diff)
downloadlinux-1e9d63331f8fa556f31e1406ab12f2a1e5cdb495.tar.xz
fs: correctly document the inode dirty flags
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@kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'include/linux/fs.h')
-rw-r--r--include/linux/fs.h18
1 files changed, 13 insertions, 5 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd47deea7c17..45a0303b2aeb 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