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     1ˆÇÊ„_ŸÆ¿Ì .Œ    1/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FILELOCK_H
#define _LINUX_FILELOCK_H

#include <linux/fs.h>

#define FL_POSIX	1
#define FL_FLOCK	2
#define FL_DELEG	4	/* NFSv4 delegation */
#define FL_ACCESS	8	/* not trying to lock, just looking */
#define FL_EXISTS	16	/* when unlocking, test for existence */
#define FL_LEASE	32	/* lease held on this file */
#define FL_CLOSE	64	/* unlock on close */
#define FL_SLEEP	128	/* A blocking lock */
#define FL_DOWNGRADE_PENDING	256 /* Lease is being downgraded */
#define FL_UNLOCK_PENDING	512 /* Lease is being broken */
#define FL_OFDLCK	1024	/* lock is "owned" by struct file */
#define FL_LAYOUT	2048	/* outstanding pNFS layout */
#define FL_RECLAIM	4096	/* reclaiming from a reboot server */

#define FL_CLOSE_POSIX (FL_POSIX | FL_CLOSE)

/*
 * Special return value from posix_lock_file() and vfs_lock_file() for
 * asynchronous locking.
 */
#define FILE_LOCK_DEFERRED 1

struct file_lock;

struct file_lock_operations {
	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
	void (*fl_release_private)(struct file_lock *);
};

struct lock_manager_operations {
	void *lm_mod_owner;
	fl_owner_t (*lm_get_owner)(fl_owner_t);
	void (*lm_put_owner)(fl_owner_t);
	void (*lm_notify)(struct file_lock *);	/* unblock callback */
	int (*lm_grant)(struct file_lock *, int);
	bool (*lm_break)(struct file_lock *);
	int (*lm_change)(struct file_lock *, int, struct list_head *);
	void (*lm_setup)(struct file_lock *, void **);
	bool (*lm_breaker_owns_lease)(struct file_lock *);
	bool (*lm_lock_expirable)(struct file_lock *cfl);
	void (*lm_expire_lock)(void);
};

struct lock_manager {
	struct list_head list;
	/*
	 * NFSv4 and up also want opens blocked during the grace period;
	 * NLM doesn't care:
	 */
	bool block_opens;
};

struct net;
void locks_start_grace(struct net *, struct lock_manager *);
void locks_end_grace(struct lock_manager *);
bool locks_in_grace(struct net *);
bool opens_in_grace(struct net *);

/*
 * struct file_lock has a union that some filesystems use to track
 * their own private info. The NFS side of things is defined here:
 */
#include <linux/nfs_fs_i.h>

/*
 * struct file_lock represents a generic "file lock". It's used to represent
 * POSIX byte range locks, BSD (flock) locks, and leases. It's important to
 * note that the same struct is used to represent both a request for a lock and
 * the lock itself, but the same object is never used for both.
 *
 * FIXME: should we create a separate "struct lock_request" to help distinguish
 * these two uses?
 *
 * The varous i_flctx lists are ordered by:
 *
 * 1) lock owner
 * 2) lock range start
 * 3) lock range end
 *
 * Obviously, the last two criteria only matter for POSIX locks.
 */
struct file_lock {
	struct file_lock *fl_blocker;	/* The lock, that is blocking us */
	struct list_head fl_list;	/* link into file_lock_context */
	struct hlist_node fl_link;	/* node in global lists */
	struct list_head fl_blocked_requests;	/* list of requests with
						 * ->fl_blocker pointing here
						 */
	struct list_head fl_blocked_member;	/* node in
						 * ->fl_blocker->fl_blocked_requests
						 */
	fl_owner_t fl_owner;
	unsigned int fl_flags;
	unsigned char fl_type;
	unsigned int fl_pid;
	int fl_link_cpu;		/* what cpu's list is this on? */
	wait_queue_head_t fl_wait;
	struct file *fl_file;
	loff_t fl_start;
	loff_t fl_end;

	struct fasync_struct *	fl_fasync; /* for lease break notifications */
	/* for lease breaks: */
	unsigned long fl_break_time;
	unsigned long fl_downgrade_time;

	const struct file_lock_operations *fl_ops;	/* Callbacks for filesystems */
	const struct lock_manager_operations *fl_lmops;	/* Callbacks for lockmanagers */
	union {
		struct nfs_lock_info	nfs_fl;
		struct nfs4_lock_info	nfs4_fl;
		struct {
			struct list_head link;	/* link in AFS vnode's pending_locks list */
			int state;		/* state of grant or error if -ve */
			unsigned int	debug_id;
		} afs;
		struct {
			struct inode *inode;
		} ceph;
	} fl_u;
} __randomize_layout;

struct file_lock_context {
	spinlock_t		flc