fs: create __sb_write_started() helper

Similar to sb_write_started() for use by other sb freeze levels.

Unlike the boolean sb_write_started(), this helper returns a tristate
to distiguish the cases of lockdep disabled or unknown lock state.

This is needed for fanotify "pre content" events.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-15-amir73il@gmail.com
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 98b7a7a8c42e36cc140d14797cf8eb00f7c36f76..ac8b5a9b467b7e3fe382719ea8eecbfd5ddedf07 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1645,9 +1645,23 @@ 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_)
 
+/**
+ * __sb_write_started - check if sb freeze level is held
+ * @sb: the super we write to
+ * @level: the freeze level
+ *
+ * > 0 sb freeze level is held
+ *   0 sb freeze level is not held
+ * < 0 !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN
+ */
+static inline int __sb_write_started(const struct super_block *sb, int level)
+{
+       return lockdep_is_held_type(sb->s_writers.rw_sem + level - 1, 1);
+}
+
 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);
+       return __sb_write_started(sb, SB_FREEZE_WRITE);
 }
 
 /**