aio, io_uring, cachefiles and overlayfs, all open code an ugly variant
of file_{start,end}_write() to silence lockdep warnings.
Create helpers for this lockdep dance so we can use the helpers in all
the callers.
Suggested-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
include/linux/fs.h | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ced388aff51f..2548048a6e6c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2579,6 +2579,42 @@ static inline void file_end_write(struct file *file)
sb_end_write(file_inode(file)->i_sb);
}
+/**
+ * kiocb_start_write - get write access to a superblock for async file io
+ * @iocb: the io context we want to submit the write with
+ *
+ * This is a variant of sb_start_write() for async io submission.
+ * Should be matched with a call to kiocb_end_write().
+ */
+static inline void kiocb_start_write(struct kiocb *iocb)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ sb_start_write(inode->i_sb);
+ /*
+ * Fool lockdep by telling it the lock got released so that it
+ * doesn't complain about the held lock when we return to userspace.
+ */
+ __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
+}
+
+/**
+ * kiocb_end_write - drop write access to a superblock after async file io
+ * @iocb: the io context we sumbitted the write with
+ *
+ * Should be matched with a call to kiocb_start_write().
+ */
+static inline void kiocb_end_write(struct kiocb *iocb)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+
+ /*
+ * Tell lockdep we inherited freeze protection from submission thread.
+ */
+ __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+ sb_end_write(inode->i_sb);
+}
+
/*
* This is used for regular files where some users -- especially the
* currently executed binary in a process, previously handled via
--
2.34.1
