AFS: export a couple of core functions for AFS write support

[net-next-2.6.git] / fs / afs / internal.h

/* internal AFS stuff
 *
 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/skbuff.h>
#include <linux/rxrpc.h>
#include <linux/key.h>
#include "afs.h"
#include "afs_vl.h"

#define AFS_CELL_MAX_ADDRS 15

struct afs_call;

typedef enum {
	AFS_VL_NEW,			/* new, uninitialised record */
	AFS_VL_CREATING,		/* creating record */
	AFS_VL_VALID,			/* record is pending */
	AFS_VL_NO_VOLUME,		/* no such volume available */
	AFS_VL_UPDATING,		/* update in progress */
	AFS_VL_VOLUME_DELETED,		/* volume was deleted */
	AFS_VL_UNCERTAIN,		/* uncertain state (update failed) */
} __attribute__((packed)) afs_vlocation_state_t;

struct afs_mount_params {
	bool			rwpath;		/* T if the parent should be considered R/W */
	bool			force;		/* T to force cell type */
	afs_voltype_t		type;		/* type of volume requested */
	int			volnamesz;	/* size of volume name */
	const char		*volname;	/* name of volume to mount */
	struct afs_cell		*cell;		/* cell in which to find volume */
	struct afs_volume	*volume;	/* volume record */
	struct key		*key;		/* key to use for secure mounting */
};

/*
 * definition of how to wait for the completion of an operation
 */
struct afs_wait_mode {
	/* RxRPC received message notification */
	void (*rx_wakeup)(struct afs_call *call);

	/* synchronous call waiter and call dispatched notification */
	int (*wait)(struct afs_call *call);

	/* asynchronous call completion */
	void (*async_complete)(void *reply, int error);
};

extern const struct afs_wait_mode afs_sync_call;
extern const struct afs_wait_mode afs_async_call;

/*
 * a record of an in-progress RxRPC call
 */
struct afs_call {
	const struct afs_call_type *type;	/* type of call */
	const struct afs_wait_mode *wait_mode;	/* completion wait mode */
	wait_queue_head_t	waitq;		/* processes awaiting completion */
	struct work_struct	async_work;	/* asynchronous work processor */
	struct work_struct	work;		/* actual work processor */
	struct sk_buff_head	rx_queue;	/* received packets */
	struct rxrpc_call	*rxcall;	/* RxRPC call handle */
	struct key		*key;		/* security for this call */
	struct afs_server	*server;	/* server affected by incoming CM call */
	void			*request;	/* request data (first part) */
	void			*request2;	/* request data (second part) */
	void			*buffer;	/* reply receive buffer */
	void			*reply;		/* reply buffer (first part) */
	void			*reply2;	/* reply buffer (second part) */
	void			*reply3;	/* reply buffer (third part) */
	void			*reply4;	/* reply buffer (fourth part) */
	enum {					/* call state */
		AFS_CALL_REQUESTING,	/* request is being sent for outgoing call */
		AFS_CALL_AWAIT_REPLY,	/* awaiting reply to outgoing call */
		AFS_CALL_AWAIT_OP_ID,	/* awaiting op ID on incoming call */
		AFS_CALL_AWAIT_REQUEST,	/* awaiting request data on incoming call */
		AFS_CALL_REPLYING,	/* replying to incoming call */
		AFS_CALL_AWAIT_ACK,	/* awaiting final ACK of incoming call */
		AFS_CALL_COMPLETE,	/* successfully completed */
		AFS_CALL_BUSY,		/* server was busy */
		AFS_CALL_ABORTED,	/* call was aborted */
		AFS_CALL_ERROR,		/* call failed due to error */
	}			state;
	int			error;		/* error code */
	unsigned		request_size;	/* size of request data */
	unsigned		reply_max;	/* maximum size of reply */
	unsigned		reply_size;	/* current size of reply */
	unsigned short		offset;		/* offset into received data store */
	unsigned char		unmarshall;	/* unmarshalling phase */
	bool			incoming;	/* T if incoming call */
	u16			service_id;	/* RxRPC service ID to call */
	__be16			port;		/* target UDP port */
	__be32			operation_ID;	/* operation ID for an incoming call */
	u32			count;		/* count for use in unmarshalling */
	__be32			tmp;		/* place to extract temporary data */
};

struct afs_call_type {
	const char *name;

	/* deliver request or reply data to an call
	 * - returning an error will cause the call to be aborted
	 */
	int (*deliver)(struct afs_call *call, struct sk_buff *skb,
		       bool last);

	/* map an abort code to an error number */
	int (*abort_to_error)(u32 abort_code);

	/* clean up a call */
	void (*destructor)(struct afs_call *call);
};

/*
 * AFS superblock private data
 * - there's one superblock per volume
 */
struct afs_super_info {
	struct afs_volume	*volume;	/* volume record */
	char			rwparent;	/* T if parent is R/W AFS volume */
};

static inline struct afs_super_info *AFS_FS_S(struct super_block *sb)
{
	return sb->s_fs_info;
}

extern struct file_system_type afs_fs_type;

/*
 * entry in the cached cell catalogue
 */
struct afs_cache_cell {
	char		name[AFS_MAXCELLNAME];	/* cell name (padded with NULs) */
	struct in_addr	vl_servers[15];		/* cached cell VL servers */
};

/*
 * AFS cell record
 */
struct afs_cell {
	atomic_t		usage;
	struct list_head	link;		/* main cell list link */
	struct key		*anonymous_key;	/* anonymous user key for this cell */
	struct list_head	proc_link;	/* /proc cell list link */
	struct proc_dir_entry	*proc_dir;	/* /proc dir for this cell */
#ifdef AFS_CACHING_SUPPORT
	struct cachefs_cookie	*cache;		/* caching cookie */
#endif

	/* server record management */
	rwlock_t		servers_lock;	/* active server list lock */
	struct list_head	servers;	/* active server list */

	/* volume location record management */
	struct rw_semaphore	vl_sem;		/* volume management serialisation semaphore */
	struct list_head	vl_list;	/* cell's active VL record list */
	spinlock_t		vl_lock;	/* vl_list lock */
	unsigned short		vl_naddrs;	/* number of VL servers in addr list */
	unsigned short		vl_curr_svix;	/* current server index */
	struct in_addr		vl_addrs[AFS_CELL_MAX_ADDRS];	/* cell VL server addresses */

	char			name[0];	/* cell name - must go last */
};

/*
 * entry in the cached volume location catalogue
 */
struct afs_cache_vlocation {
	/* volume name (lowercase, padded with NULs) */
	uint8_t			name[AFS_MAXVOLNAME + 1];

	uint8_t			nservers;	/* number of entries used in servers[] */
	uint8_t			vidmask;	/* voltype mask for vid[] */
	uint8_t			srvtmask[8];	/* voltype masks for servers[] */
#define AFS_VOL_VTM_RW	0x01 /* R/W version of the volume is available (on this server) */
#define AFS_VOL_VTM_RO	0x02 /* R/O version of the volume is available (on this server) */
#define AFS_VOL_VTM_BAK	0x04 /* backup version of the volume is available (on this server) */

	afs_volid_t		vid[3];		/* volume IDs for R/W, R/O and Bak volumes */
	struct in_addr		servers[8];	/* fileserver addresses */
	time_t			rtime;		/* last retrieval time */
};

/*
 * volume -> vnode hash table entry
 */
struct afs_cache_vhash {
	afs_voltype_t		vtype;		/* which volume variation */
	uint8_t			hash_bucket;	/* which hash bucket this represents */
} __attribute__((packed));

/*
 * AFS volume location record
 */
struct afs_vlocation {
	atomic_t		usage;
	time_t			time_of_death;	/* time at which put reduced usage to 0 */
	struct list_head	link;		/* link in cell volume location list */
	struct list_head	grave;		/* link in master graveyard list */
	struct list_head	update;		/* link in master update list */
	struct afs_cell		*cell;		/* cell to which volume belongs */
#ifdef AFS_CACHING_SUPPORT
	struct cachefs_cookie	*cache;		/* caching cookie */
#endif
	struct afs_cache_vlocation vldb;	/* volume information DB record */
	struct afs_volume	*vols[3];	/* volume access record pointer (index by type) */
	wait_queue_head_t	waitq;		/* status change waitqueue */
	time_t			update_at;	/* time at which record should be updated */
	spinlock_t		lock;		/* access lock */
	afs_vlocation_state_t	state;		/* volume location state */
	unsigned short		upd_rej_cnt;	/* ENOMEDIUM count during update */
	unsigned short		upd_busy_cnt;	/* EBUSY count during update */
	bool			valid;		/* T if valid */
};

/*
 * AFS fileserver record
 */
struct afs_server {
	atomic_t		usage;
	time_t			time_of_death;	/* time at which put reduced usage to 0 */
	struct in_addr		addr;		/* server address */
	struct afs_cell		*cell;		/* cell in which server resides */
	struct list_head	link;		/* link in cell's server list */
	struct list_head	grave;		/* link in master graveyard list */
	struct rb_node		master_rb;	/* link in master by-addr tree */
	struct rw_semaphore	sem;		/* access lock */

	/* file service access */
	struct rb_root		fs_vnodes;	/* vnodes backed by this server (ordered by FID) */
	unsigned long		fs_act_jif;	/* time at which last activity occurred */
	unsigned long		fs_dead_jif;	/* time at which no longer to be considered dead */
	spinlock_t		fs_lock;	/* access lock */
	int			fs_state;      	/* 0 or reason FS currently marked dead (-errno) */

	/* callback promise management */
	struct rb_root		cb_promises;	/* vnode expiration list (ordered earliest first) */
	struct delayed_work	cb_updater;	/* callback updater */
	struct delayed_work	cb_break_work;	/* collected break dispatcher */
	wait_queue_head_t	cb_break_waitq;	/* space available in cb_break waitqueue */
	spinlock_t		cb_lock;	/* access lock */
	struct afs_callback	cb_break[64];	/* ring of callbacks awaiting breaking */
	atomic_t		cb_break_n;	/* number of pending breaks */
	u8			cb_break_head;	/* head of callback breaking ring */
	u8			cb_break_tail;	/* tail of callback breaking ring */
};

/*
 * AFS volume access record
 */
struct afs_volume {
	atomic_t		usage;
	struct afs_cell		*cell;		/* cell to which belongs (unrefd ptr) */
	struct afs_vlocation	*vlocation;	/* volume location */
#ifdef AFS_CACHING_SUPPORT
	struct cachefs_cookie	*cache;		/* caching cookie */
#endif
	afs_volid_t		vid;		/* volume ID */
	afs_voltype_t		type;		/* type of volume */
	char			type_force;	/* force volume type (suppress R/O -> R/W) */
	unsigned short		nservers;	/* number of server slots filled */
	unsigned short		rjservers;	/* number of servers discarded due to -ENOMEDIUM */
	struct afs_server	*servers[8];	/* servers on which volume resides (ordered) */
	struct rw_semaphore	server_sem;	/* lock for accessing current server */
};

/*
 * vnode catalogue entry
 */
struct afs_cache_vnode {
	afs_vnodeid_t		vnode_id;	/* vnode ID */
	unsigned		vnode_unique;	/* vnode ID uniquifier */
	afs_dataversion_t	data_version;	/* data version */
};

/*
 * AFS inode private data
 */
struct afs_vnode {
	struct inode		vfs_inode;	/* the VFS's inode record */

	struct afs_volume	*volume;	/* volume on which vnode resides */
	struct afs_server	*server;	/* server currently supplying this file */
	struct afs_fid		fid;		/* the file identifier for this inode */
	struct afs_file_status	status;		/* AFS status info for this file */
#ifdef AFS_CACHING_SUPPORT
	struct cachefs_cookie	*cache;		/* caching cookie */
#endif
	struct afs_permits	*permits;	/* cache of permits so far obtained */
	struct mutex		permits_lock;	/* lock for altering permits list */
	struct mutex		validate_lock;	/* lock for validating this vnode */
	wait_queue_head_t	update_waitq;	/* status fetch waitqueue */
	int			update_cnt;	/* number of outstanding ops that will update the
						 * status */
	spinlock_t		lock;		/* waitqueue/flags lock */
	unsigned long		flags;
#define AFS_VNODE_CB_BROKEN	0		/* set if vnode's callback was broken */
#define AFS_VNODE_UNSET		1		/* set if vnode attributes not yet set */
#define AFS_VNODE_MODIFIED	2		/* set if vnode's data modified */
#define AFS_VNODE_ZAP_DATA	3		/* set if vnode's data should be invalidated */
#define AFS_VNODE_DELETED	4		/* set if vnode deleted on server */
#define AFS_VNODE_MOUNTPOINT	5		/* set if vnode is a mountpoint symlink */

	long			acl_order;	/* ACL check count (callback break count) */

	/* outstanding callback notification on this file */
	struct rb_node		server_rb;	/* link in server->fs_vnodes */
	struct rb_node		cb_promise;	/* link in server->cb_promises */
	struct work_struct	cb_broken_work;	/* work to be done on callback break */
	time_t			cb_expires;	/* time at which callback expires */
	time_t			cb_expires_at;	/* time used to order cb_promise */
	unsigned		cb_version;	/* callback version */
	unsigned		cb_expiry;	/* callback expiry time */
	afs_callback_type_t	cb_type;	/* type of callback */
	bool			cb_promised;	/* true if promise still holds */
};

/*
 * cached security record for one user's attempt to access a vnode
 */
struct afs_permit {
	struct key		*key;		/* RxRPC ticket holding a security context */
	afs_access_t		access_mask;	/* access mask for this key */
};

/*
 * cache of security records from attempts to access a vnode
 */
struct afs_permits {
	struct rcu_head		rcu;		/* disposal procedure */
	int			count;		/* number of records */
	struct afs_permit	permits[0];	/* the permits so far examined */
};

/*
 * record of one of a system's set of network interfaces
 */
struct afs_interface {
	struct in_addr	address;	/* IPv4 address bound to interface */
	struct in_addr	netmask;	/* netmask applied to address */
	unsigned	mtu;		/* MTU of interface */
};

/*
 * UUID definition [internet draft]
 * - the timestamp is a 60-bit value, split 32/16/12, and goes in 100ns
 *   increments since midnight 15th October 1582
 *   - add AFS_UUID_TO_UNIX_TIME to convert unix time in 100ns units to UUID
 *     time
 * - the clock sequence is a 14-bit counter to avoid duplicate times
 */
struct afs_uuid {
	u32		time_low;			/* low part of timestamp */
	u16		time_mid;			/* mid part of timestamp */
	u16		time_hi_and_version;		/* high part of timestamp and version  */
#define AFS_UUID_TO_UNIX_TIME	0x01b21dd213814000ULL
#define AFS_UUID_TIMEHI_MASK	0x0fff
#define AFS_UUID_VERSION_TIME	0x1000	/* time-based UUID */
#define AFS_UUID_VERSION_NAME	0x3000	/* name-based UUID */
#define AFS_UUID_VERSION_RANDOM	0x4000	/* (pseudo-)random generated UUID */
	u8		clock_seq_hi_and_reserved;	/* clock seq hi and variant */
#define AFS_UUID_CLOCKHI_MASK	0x3f
#define AFS_UUID_VARIANT_STD	0x80
	u8		clock_seq_low;			/* clock seq low */
	u8		node[6];			/* spatially unique node ID (MAC addr) */
};

/*****************************************************************************/
/*
 * callback.c
 */
extern void afs_init_callback_state(struct afs_server *);
extern void afs_broken_callback_work(struct work_struct *);
extern void afs_break_callbacks(struct afs_server *, size_t,
				struct afs_callback[]);
extern void afs_discard_callback_on_delete(struct afs_vnode *);
extern void afs_give_up_callback(struct afs_vnode *);
extern void afs_dispatch_give_up_callbacks(struct work_struct *);
extern void afs_flush_callback_breaks(struct afs_server *);
extern int __init afs_callback_update_init(void);
extern void afs_callback_update_kill(void);

/*
 * cell.c
 */
extern struct rw_semaphore afs_proc_cells_sem;
extern struct list_head afs_proc_cells;
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_cache_cell_index_def;
#endif

#define afs_get_cell(C) do { atomic_inc(&(C)->usage); } while(0)
extern int afs_cell_init(char *);
extern struct afs_cell *afs_cell_create(const char *, char *);
extern struct afs_cell *afs_cell_lookup(const char *, unsigned);
extern struct afs_cell *afs_grab_cell(struct afs_cell *);
extern void afs_put_cell(struct afs_cell *);
extern void afs_cell_purge(void);

/*
 * cmservice.c
 */
extern bool afs_cm_incoming_call(struct afs_call *);

/*
 * dir.c
 */
extern const struct inode_operations afs_dir_inode_operations;
extern const struct file_operations afs_dir_file_operations;

extern int afs_permission(struct inode *, int, struct nameidata *);

/*
 * file.c
 */
extern const struct address_space_operations afs_fs_aops;
extern const struct inode_operations afs_file_inode_operations;
extern const struct file_operations afs_file_operations;

extern int afs_open(struct inode *, struct file *);
extern int afs_release(struct inode *, struct file *);

#ifdef AFS_CACHING_SUPPORT
extern int afs_cache_get_page_cookie(struct page *, struct cachefs_page **);
#endif

/*
 * fsclient.c
 */
extern int afs_fs_fetch_file_status(struct afs_server *, struct key *,
				    struct afs_vnode *, struct afs_volsync *,
				    const struct afs_wait_mode *);
extern int afs_fs_give_up_callbacks(struct afs_server *,
				    const struct afs_wait_mode *);
extern int afs_fs_fetch_data(struct afs_server *, struct key *,
			     struct afs_vnode *, off_t, size_t, struct page *,
			     const struct afs_wait_mode *);
extern int afs_fs_create(struct afs_server *, struct key *,
			 struct afs_vnode *, const char *, umode_t,
			 struct afs_fid *, struct afs_file_status *,
			 struct afs_callback *,
			 const struct afs_wait_mode *);
extern int afs_fs_remove(struct afs_server *, struct key *,
			 struct afs_vnode *, const char *, bool,
			 const struct afs_wait_mode *);
extern int afs_fs_link(struct afs_server *, struct key *, struct afs_vnode *,
		       struct afs_vnode *, const char *,
		       const struct afs_wait_mode *);
extern int afs_fs_symlink(struct afs_server *, struct key *,
			  struct afs_vnode *, const char *, const char *,
			  struct afs_fid *, struct afs_file_status *,
			  const struct afs_wait_mode *);
extern int afs_fs_rename(struct afs_server *, struct key *,
			 struct afs_vnode *, const char *,
			 struct afs_vnode *, const char *,
			 const struct afs_wait_mode *);

/*
 * inode.c
 */
extern struct inode *afs_iget(struct super_block *, struct key *,
			      struct afs_fid *, struct afs_file_status *,
			      struct afs_callback *);
extern int afs_validate(struct afs_vnode *, struct key *);
extern int afs_inode_getattr(struct vfsmount *, struct dentry *,
			     struct kstat *);
extern void afs_zap_permits(struct rcu_head *);
extern void afs_clear_inode(struct inode *);

/*
 * main.c
 */
extern struct afs_uuid afs_uuid;
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_netfs afs_cache_netfs;
#endif

/*
 * misc.c
 */
extern int afs_abort_to_error(u32);

/*
 * mntpt.c
 */
extern const struct inode_operations afs_mntpt_inode_operations;
extern const struct file_operations afs_mntpt_file_operations;
extern unsigned long afs_mntpt_expiry_timeout;

extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
extern void afs_mntpt_kill_timer(void);
extern void afs_umount_begin(struct vfsmount *, int);

/*
 * proc.c
 */
extern int afs_proc_init(void);
extern void afs_proc_cleanup(void);
extern int afs_proc_cell_setup(struct afs_cell *);
extern void afs_proc_cell_remove(struct afs_cell *);

/*
 * rxrpc.c
 */
extern int afs_open_socket(void);
extern void afs_close_socket(void);
extern int afs_make_call(struct in_addr *, struct afs_call *, gfp_t,
			 const struct afs_wait_mode *);
extern struct afs_call *afs_alloc_flat_call(const struct afs_call_type *,
					    size_t, size_t);
extern void afs_flat_call_destructor(struct afs_call *);
extern void afs_transfer_reply(struct afs_call *, struct sk_buff *);
extern void afs_send_empty_reply(struct afs_call *);
extern void afs_send_simple_reply(struct afs_call *, const void *, size_t);
extern int afs_extract_data(struct afs_call *, struct sk_buff *, bool, void *,
			    size_t);

/*
 * security.c
 */
extern void afs_clear_permits(struct afs_vnode *);
extern void afs_cache_permit(struct afs_vnode *, struct key *, long);
extern struct key *afs_request_key(struct afs_cell *);
extern int afs_permission(struct inode *, int, struct nameidata *);

/*
 * server.c
 */
extern spinlock_t afs_server_peer_lock;

#define afs_get_server(S)					\
do {								\
	_debug("GET SERVER %d", atomic_read(&(S)->usage));	\
	atomic_inc(&(S)->usage);				\
} while(0)

extern struct afs_server *afs_lookup_server(struct afs_cell *,
					    const struct in_addr *);
extern struct afs_server *afs_find_server(const struct in_addr *);
extern void afs_put_server(struct afs_server *);
extern void __exit afs_purge_servers(void);

/*
 * super.c
 */
extern int afs_fs_init(void);
extern void afs_fs_exit(void);

/*
 * use-rtnetlink.c
 */
extern int afs_get_ipv4_interfaces(struct afs_interface *, size_t, bool);
extern int afs_get_MAC_address(u8 *, size_t);

/*
 * vlclient.c
 */
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_vlocation_cache_index_def;
#endif

extern int afs_vl_get_entry_by_name(struct in_addr *, struct key *,
				    const char *, struct afs_cache_vlocation *,
				    const struct afs_wait_mode *);
extern int afs_vl_get_entry_by_id(struct in_addr *, struct key *,
				  afs_volid_t, afs_voltype_t,
				  struct afs_cache_vlocation *,
				  const struct afs_wait_mode *);

/*
 * vlocation.c
 */
#define afs_get_vlocation(V) do { atomic_inc(&(V)->usage); } while(0)

extern int __init afs_vlocation_update_init(void);
extern struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *,
						  struct key *,
						  const char *, size_t);
extern void afs_put_vlocation(struct afs_vlocation *);
extern void afs_vlocation_purge(void);

/*
 * vnode.c
 */
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_vnode_cache_index_def;
#endif

extern struct afs_timer_ops afs_vnode_cb_timed_out_ops;

static inline struct afs_vnode *AFS_FS_I(struct inode *inode)
{
	return container_of(inode, struct afs_vnode, vfs_inode);
}

static inline struct inode *AFS_VNODE_TO_I(struct afs_vnode *vnode)
{
	return &vnode->vfs_inode;
}

extern void afs_vnode_finalise_status_update(struct afs_vnode *,
					     struct afs_server *);
extern int afs_vnode_fetch_status(struct afs_vnode *, struct afs_vnode *,
				  struct key *);
extern int afs_vnode_fetch_data(struct afs_vnode *, struct key *,
				off_t, size_t, struct page *);
extern int afs_vnode_create(struct afs_vnode *, struct key *, const char *,
			    umode_t, struct afs_fid *, struct afs_file_status *,
			    struct afs_callback *, struct afs_server **);
extern int afs_vnode_remove(struct afs_vnode *, struct key *, const char *,
			    bool);
extern int afs_vnode_link(struct afs_vnode *, struct afs_vnode *, struct key *,
			  const char *);
extern int afs_vnode_symlink(struct afs_vnode *, struct key *, const char *,
			     const char *, struct afs_fid *,
			     struct afs_file_status *, struct afs_server **);
extern int afs_vnode_rename(struct afs_vnode *, struct afs_vnode *,
			    struct key *, const char *, const char *);

/*
 * volume.c
 */
#ifdef AFS_CACHING_SUPPORT
extern struct cachefs_index_def afs_volume_cache_index_def;
#endif

#define afs_get_volume(V) do { atomic_inc(&(V)->usage); } while(0)

extern void afs_put_volume(struct afs_volume *);
extern struct afs_volume *afs_volume_lookup(struct afs_mount_params *);
extern struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *);
extern int afs_volume_release_fileserver(struct afs_vnode *,
					 struct afs_server *, int);

/*****************************************************************************/
/*
 * debug tracing
 */
extern unsigned afs_debug;

#define dbgprintk(FMT,...) \
	printk("[%x%-6.6s] "FMT"\n", smp_processor_id(), current->comm ,##__VA_ARGS__)

/* make sure we maintain the format strings, even when debugging is disabled */
static inline __attribute__((format(printf,1,2)))
void _dbprintk(const char *fmt, ...)
{
}

#define kenter(FMT,...)	dbgprintk("==> %s("FMT")",__FUNCTION__ ,##__VA_ARGS__)
#define kleave(FMT,...)	dbgprintk("<== %s()"FMT"",__FUNCTION__ ,##__VA_ARGS__)
#define kdebug(FMT,...)	dbgprintk("    "FMT ,##__VA_ARGS__)


#if defined(__KDEBUG)
#define _enter(FMT,...)	kenter(FMT,##__VA_ARGS__)
#define _leave(FMT,...)	kleave(FMT,##__VA_ARGS__)
#define _debug(FMT,...)	kdebug(FMT,##__VA_ARGS__)

#elif defined(CONFIG_AFS_DEBUG)
#define AFS_DEBUG_KENTER	0x01
#define AFS_DEBUG_KLEAVE	0x02
#define AFS_DEBUG_KDEBUG	0x04

#define _enter(FMT,...)					\
do {							\
	if (unlikely(afs_debug & AFS_DEBUG_KENTER))	\
		kenter(FMT,##__VA_ARGS__);		\
} while (0)

#define _leave(FMT,...)					\
do {							\
	if (unlikely(afs_debug & AFS_DEBUG_KLEAVE))	\
		kleave(FMT,##__VA_ARGS__);		\
} while (0)

#define _debug(FMT,...)					\
do {							\
	if (unlikely(afs_debug & AFS_DEBUG_KDEBUG))	\
		kdebug(FMT,##__VA_ARGS__);		\
} while (0)

#else
#define _enter(FMT,...)	_dbprintk("==> %s("FMT")",__FUNCTION__ ,##__VA_ARGS__)
#define _leave(FMT,...)	_dbprintk("<== %s()"FMT"",__FUNCTION__ ,##__VA_ARGS__)
#define _debug(FMT,...)	_dbprintk("    "FMT ,##__VA_ARGS__)
#endif

/*
 * debug assertion checking
 */
#if 1 // defined(__KDEBUGALL)

#define ASSERT(X)						\
do {								\
	if (unlikely(!(X))) {					\
		printk(KERN_ERR "\n");				\
		printk(KERN_ERR "AFS: Assertion failed\n");	\
		BUG();						\
	}							\
} while(0)

#define ASSERTCMP(X, OP, Y)						\
do {									\
	if (unlikely(!((X) OP (Y)))) {					\
		printk(KERN_ERR "\n");					\
		printk(KERN_ERR "AFS: Assertion failed\n");		\
		printk(KERN_ERR "%lu " #OP " %lu is false\n",		\
		       (unsigned long)(X), (unsigned long)(Y));		\
		printk(KERN_ERR "0x%lx " #OP " 0x%lx is false\n",	\
		       (unsigned long)(X), (unsigned long)(Y));		\
		BUG();							\
	}								\
} while(0)

#define ASSERTIF(C, X)						\
do {								\
	if (unlikely((C) && !(X))) {				\
		printk(KERN_ERR "\n");				\
		printk(KERN_ERR "AFS: Assertion failed\n");	\
		BUG();						\
	}							\
} while(0)

#define ASSERTIFCMP(C, X, OP, Y)					\
do {									\
	if (unlikely((C) && !((X) OP (Y)))) {				\
		printk(KERN_ERR "\n");					\
		printk(KERN_ERR "AFS: Assertion failed\n");		\
		printk(KERN_ERR "%lu " #OP " %lu is false\n",		\
		       (unsigned long)(X), (unsigned long)(Y));		\
		printk(KERN_ERR "0x%lx " #OP " 0x%lx is false\n",	\
		       (unsigned long)(X), (unsigned long)(Y));		\
		BUG();							\
	}								\
} while(0)

#else

#define ASSERT(X)				\
do {						\
} while(0)

#define ASSERTCMP(X, OP, Y)			\
do {						\
} while(0)

#define ASSERTIF(C, X)				\
do {						\
} while(0)

#define ASSERTIFCMP(C, X, OP, Y)		\
do {						\
} while(0)

#endif /* __KDEBUGALL */