Unverified Commit 5e9b50de authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: add f_pipe 

Only regular files with FMODE_ATOMIC_POS and directories need
f_pos_lock. Place a new f_pipe member in a union with f_pos_lock
that they can use and make them stop abusing f_version in follow-up
patches.

Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-18-6d3e4816aa7b@kernel.org


Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 1146e5a6

fs/file_table.c

+7 −0
Original line number Diff line number Diff line
@@ -156,6 +156,13 @@ static int init_file(struct file *f, int flags, const struct cred *cred) 
	}



	spin_lock_init(&f->f_lock);

	/*

	 * Note that f_pos_lock is only used for files raising

	 * FMODE_ATOMIC_POS and directories. Other files such as pipes

	 * don't need it and since f_pos_lock is in a union may reuse

	 * the space for other purposes. They are expected to initialize

	 * the respective member when opening the file.

	 */

	mutex_init(&f->f_pos_lock);

	f->f_flags = flags;

	f->f_mode = OPEN_FMODE(flags);

include/linux/fs.h

+7 −1
Original line number Diff line number Diff line
@@ -1001,6 +1001,7 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index) 
 * @f_cred: stashed credentials of creator/opener

 * @f_path: path of the file

 * @f_pos_lock: lock protecting file position

 * @f_pipe: specific to pipes

 * @f_pos: file position

 * @f_version: file version

 * @f_security: LSM security context of this file
@@ -1026,7 +1027,12 @@ struct file { 
	const struct cred		*f_cred;

	/* --- cacheline 1 boundary (64 bytes) --- */

	struct path			f_path;

	union {

		/* regular files (with FMODE_ATOMIC_POS) and directories */

		struct mutex		f_pos_lock;

		/* pipes */

		u64			f_pipe;

	};

	loff_t				f_pos;

	u64				f_version;

	/* --- cacheline 2 boundary (128 bytes) --- */