From: Naohiro Aota <naohiro.aota@wdc.com>
Date: Tue, 29 Mar 2022 06:55:59 +0000 (+0900)
Subject: fs: add a lockdep check function for sb_start_write()
X-Git-Tag: for-5.19/block-exec-2022-06-02~64^2~112
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=7f8d12ea96352275c2850c24a1367166179392d2;p=linux-2.6-block.git

fs: add a lockdep check function for sb_start_write()

Add a function sb_write_started() to allow callers to verify if
sb_start_write() is properly called. It will be used for assertion in
btrfs.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/include/linux/fs.h b/include/linux/fs.h
index bbde95387a23..01d61984ce7a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1708,6 +1708,11 @@ static inline bool __sb_start_write_trylock(struct super_block *sb, int level)
 #define __sb_writers_release(sb, lev)	\
 	percpu_rwsem_release(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
 
+static inline bool sb_write_started(const struct super_block *sb)
+{
+	return lockdep_is_held_type(sb->s_writers.rw_sem + SB_FREEZE_WRITE - 1, 1);
+}
+
 /**
  * sb_end_write - drop write access to a superblock
  * @sb: the super we wrote to