[PATCH v9 1/4] fs: add iput_if_not_last() helper
From: Yun Zhou <hidden>
Date: 2026-06-23 08:38:12
Also in:
lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Add a helper that drops an inode reference only if the caller does not hold the last one. Returns true if the reference was dropped, false otherwise. This is useful for filesystems that need to release inode references in contexts where triggering final iput (and thus eviction) would be unsafe due to lock ordering constraints. The caller can check the return value and defer the final iput to a safe context. Unlike iput_not_last() which BUG_ON's if called with the last ref, this variant is designed to be called speculatively. Signed-off-by: Yun Zhou <redacted> Suggested-by: Jan Kara <jack@suse.cz> --- include/linux/fs.h | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6da44573ce45..4916a9d54347 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -2418,6 +2418,19 @@ static inline void super_set_sysfs_name_generic(struct super_block *sb, const ch extern void ihold(struct inode * inode); extern void iput(struct inode *); void iput_not_last(struct inode *); + +/** + * iput_if_not_last - drop an inode reference only if it is not the last one + * @inode: inode to put + * + * Returns true if the reference was dropped, false if this was the last + * reference and the caller must arrange for final iput() in a safe context. + */ +static inline bool iput_if_not_last(struct inode *inode) +{ + return atomic_add_unless(&inode->i_count, -1, 1); +} + int inode_update_time(struct inode *inode, enum fs_update_time type, unsigned int flags); int generic_update_time(struct inode *inode, enum fs_update_time type,
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2.43.0