Merge with Linux 2.4.0-test3-pre2.

[linux-2.6/linux-mips.git] / include / linux / fs.h

#ifndef _LINUX_FS_H
#define _LINUX_FS_H

/*
 * This file has definitions for some important file table
 * structures etc.
 */

#include <linux/config.h>
#include <linux/linkage.h>
#include <linux/limits.h>
#include <linux/wait.h>
#include <linux/types.h>
#include <linux/vfs.h>
#include <linux/net.h>
#include <linux/kdev_t.h>
#include <linux/ioctl.h>
#include <linux/list.h>
#include <linux/dcache.h>
#include <linux/stat.h>
#include <linux/cache.h>
#include <linux/stddef.h>
#include <linux/string.h>

#include <asm/atomic.h>
#include <asm/bitops.h>

struct poll_table_struct;


/*
 * It's silly to have NR_OPEN bigger than NR_FILE, but you can change
 * the file limit at runtime and only root can increase the per-process
 * nr_file rlimit, so it's safe to set up a ridiculously high absolute
 * upper limit on files-per-process.
 *
 * Some programs (notably those using select()) may have to be 
 * recompiled to take full advantage of the new limits..  
 */

/* Fixed constants first: */
#undef NR_OPEN
#define NR_OPEN (1024*1024)     /* Absolute upper limit on fd num */
#define INR_OPEN 1024           /* Initial setting for nfile rlimits */

#define BLOCK_SIZE_BITS 10
#define BLOCK_SIZE (1<<BLOCK_SIZE_BITS)

/* And dynamically-tunable limits and defaults: */
struct files_stat_struct {
        int nr_files;           /* read only */
        int nr_free_files;      /* read only */
        int max_files;          /* tunable */
};
extern struct files_stat_struct files_stat;
extern int max_super_blocks, nr_super_blocks;

#define NR_FILE  8192   /* this can well be larger on a larger system */
#define NR_RESERVED_FILES 10 /* reserved for root */
#define NR_SUPER 256

#define MAY_EXEC 1
#define MAY_WRITE 2
#define MAY_READ 4

#define FMODE_READ 1
#define FMODE_WRITE 2

#define READ 0
#define WRITE 1
#define READA 2         /* read-ahead  - don't block if no resources */
#define SPECIAL 4       /* For non-blockdevice requests in request queue */

#define WRITERAW 5      /* raw write - don't play with buffer lists */

#define NIL_FILP        ((struct file *)0)
#define SEL_IN          1
#define SEL_OUT         2
#define SEL_EX          4

/* public flags for file_system_type */
#define FS_REQUIRES_DEV 1 
#define FS_NO_DCACHE    2 /* Only dcache the necessary things. */
#define FS_NO_PRELIM    4 /* prevent preloading of dentries, even if
                           * FS_NO_DCACHE is not set.
                           */
#define FS_SINGLE       8 /*
                           * Filesystem that can have only one superblock;
                           * kernel-wide vfsmnt is kept in ->kern_mnt.
                           */
#define FS_NOMOUNT      16 /* Never mount from userland */
#define FS_LITTER       32 /* Keeps the tree in dcache */
/*
 * These are the fs-independent mount-flags: up to 16 flags are supported
 */
#define MS_RDONLY        1      /* Mount read-only */
#define MS_NOSUID        2      /* Ignore suid and sgid bits */
#define MS_NODEV         4      /* Disallow access to device special files */
#define MS_NOEXEC        8      /* Disallow program execution */
#define MS_SYNCHRONOUS  16      /* Writes are synced at once */
#define MS_REMOUNT      32      /* Alter flags of a mounted FS */
#define MS_MANDLOCK     64      /* Allow mandatory locks on an FS */
#define S_QUOTA         128     /* Quota initialized for file/directory/symlink */
#define S_APPEND        256     /* Append-only file */
#define S_IMMUTABLE     512     /* Immutable file */
#define MS_NOATIME      1024    /* Do not update access times. */
#define MS_NODIRATIME   2048    /* Do not update directory access times */

#define MS_ODD_RENAME   32768   /* Temporary stuff; will go away as soon
                                  * as nfs_rename() will be cleaned up
                                  */
#define S_DEAD          (1<<16) /* removed, but still open directory */

/*
 * Flags that can be altered by MS_REMOUNT
 */
#define MS_RMT_MASK     (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|\
                        MS_SYNCHRONOUS|MS_MANDLOCK|MS_NOATIME|MS_NODIRATIME)

/*
 * Magic mount flag number. Has to be or-ed to the flag values.
 */
#define MS_MGC_VAL 0xC0ED0000   /* magic flag number to indicate "new" flags */
#define MS_MGC_MSK 0xffff0000   /* magic flag number mask */

/*
 * Note that nosuid etc flags are inode-specific: setting some file-system
 * flags just means all the inodes inherit those flags by default. It might be
 * possible to override it selectively if you really wanted to with some
 * ioctl() that is not currently implemented.
 *
 * Exception: MS_RDONLY is always applied to the entire file system.
 *
 * Unfortunately, it is possible to change a filesystems flags with it mounted
 * with files in use.  This means that all of the inodes will not have their
 * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
 * flags, so these have to be checked separately. -- rmk@arm.uk.linux.org
 */
#define __IS_FLG(inode,flg) (((inode)->i_sb && (inode)->i_sb->s_flags & (flg)) \
                                || (inode)->i_flags & (flg))

#define IS_RDONLY(inode) (((inode)->i_sb) && ((inode)->i_sb->s_flags & MS_RDONLY))
#define IS_NOSUID(inode)        __IS_FLG(inode, MS_NOSUID)
#define IS_NODEV(inode)         __IS_FLG(inode, MS_NODEV)
#define IS_NOEXEC(inode)        __IS_FLG(inode, MS_NOEXEC)
#define IS_SYNC(inode)          __IS_FLG(inode, MS_SYNCHRONOUS)
#define IS_MANDLOCK(inode)      __IS_FLG(inode, MS_MANDLOCK)

#define IS_QUOTAINIT(inode)     ((inode)->i_flags & S_QUOTA)
#define IS_APPEND(inode)        ((inode)->i_flags & S_APPEND)
#define IS_IMMUTABLE(inode)     ((inode)->i_flags & S_IMMUTABLE)
#define IS_NOATIME(inode)       __IS_FLG(inode, MS_NOATIME)
#define IS_NODIRATIME(inode)    __IS_FLG(inode, MS_NODIRATIME)

#define IS_DEADDIR(inode)       ((inode)->i_flags & S_DEAD)

/* the read-only stuff doesn't really belong here, but any other place is
   probably as bad and I don't want to create yet another include file. */

#define BLKROSET   _IO(0x12,93) /* set device read-only (0 = read-write) */
#define BLKROGET   _IO(0x12,94) /* get read-only status (0 = read_write) */
#define BLKRRPART  _IO(0x12,95) /* re-read partition table */
#define BLKGETSIZE _IO(0x12,96) /* return device size */
#define BLKFLSBUF  _IO(0x12,97) /* flush buffer cache */
#define BLKRASET   _IO(0x12,98) /* Set read ahead for block device */
#define BLKRAGET   _IO(0x12,99) /* get current read ahead setting */
#define BLKFRASET  _IO(0x12,100)/* set filesystem (mm/filemap.c) read-ahead */
#define BLKFRAGET  _IO(0x12,101)/* get filesystem (mm/filemap.c) read-ahead */
#define BLKSECTSET _IO(0x12,102)/* set max sectors per request (ll_rw_blk.c) */
#define BLKSECTGET _IO(0x12,103)/* get max sectors per request (ll_rw_blk.c) */
#define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
#if 0
#define BLKPG      _IO(0x12,105)/* See blkpg.h */
#define BLKELVGET  _IOR(0x12,106,sizeof(blkelv_ioctl_arg_t))/* elevator get */
#define BLKELVSET  _IOW(0x12,107,sizeof(blkelv_ioctl_arg_t))/* elevator set */
/* This was here just to show that the number is taken -
   probably all these _IO(0x12,*) ioctls should be moved to blkpg.h. */
#endif


#define BMAP_IOCTL 1            /* obsolete - kept for compatibility */
#define FIBMAP     _IO(0x00,1)  /* bmap access */
#define FIGETBSZ   _IO(0x00,2)  /* get the block size used for bmap */

#ifdef __KERNEL__

#include <asm/semaphore.h>
#include <asm/byteorder.h>

extern void update_atime (struct inode *);
#define UPDATE_ATIME(inode) update_atime (inode)

extern void buffer_init(unsigned long);
extern void inode_init(unsigned long);
extern void file_table_init(void);
extern void dcache_init(unsigned long);

/* bh state bits */
#define BH_Uptodate     0       /* 1 if the buffer contains valid data */
#define BH_Dirty        1       /* 1 if the buffer is dirty */
#define BH_Lock         2       /* 1 if the buffer is locked */
#define BH_Req          3       /* 0 if the buffer has been invalidated */
#define BH_Mapped       4       /* 1 if the buffer has a disk mapping */
#define BH_New          5       /* 1 if the buffer is new and not yet written out */
#define BH_Protected    6       /* 1 if the buffer is protected */

/*
 * Try to keep the most commonly used fields in single cache lines (16
 * bytes) to improve performance.  This ordering should be
 * particularly beneficial on 32-bit processors.
 * 
 * We use the first 16 bytes for the data which is used in searches
 * over the block hash lists (ie. getblk() and friends).
 * 
 * The second 16 bytes we use for lru buffer scans, as used by
 * sync_buffers() and refill_freelist().  -- sct
 */
struct buffer_head {
        /* First cache line: */
        struct buffer_head *b_next;     /* Hash queue list */
        unsigned long b_blocknr;        /* block number */
        unsigned short b_size;          /* block size */
        unsigned short b_list;          /* List that this buffer appears */
        kdev_t b_dev;                   /* device (B_FREE = free) */

        atomic_t b_count;               /* users using this block */
        kdev_t b_rdev;                  /* Real device */
        unsigned long b_state;          /* buffer state bitmap (see above) */
        unsigned long b_flushtime;      /* Time when (dirty) buffer should be written */

        struct buffer_head *b_next_free;/* lru/free list linkage */
        struct buffer_head *b_prev_free;/* doubly linked list of buffers */
        struct buffer_head *b_this_page;/* circular list of buffers in one page */
        struct buffer_head *b_reqnext;  /* request queue */

        struct buffer_head **b_pprev;   /* doubly linked list of hash-queue */
        char * b_data;                  /* pointer to data block (512 byte) */
        struct page *b_page;            /* the page this bh is mapped to */
        void (*b_end_io)(struct buffer_head *bh, int uptodate); /* I/O completion */
        void *b_dev_id;

        unsigned long b_rsector;        /* Real buffer location on disk */
        wait_queue_head_t b_wait;
        struct kiobuf * b_kiobuf;       /* kiobuf which owns this IO */
};

typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
void init_buffer(struct buffer_head *, bh_end_io_t *, void *);

#define __buffer_state(bh, state)       (((bh)->b_state & (1UL << BH_##state)) != 0)

#define buffer_uptodate(bh)     __buffer_state(bh,Uptodate)
#define buffer_dirty(bh)        __buffer_state(bh,Dirty)
#define buffer_locked(bh)       __buffer_state(bh,Lock)
#define buffer_req(bh)          __buffer_state(bh,Req)
#define buffer_mapped(bh)       __buffer_state(bh,Mapped)
#define buffer_new(bh)          __buffer_state(bh,New)
#define buffer_protected(bh)    __buffer_state(bh,Protected)

#define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)

extern void set_bh_page(struct buffer_head *bh, struct page *page, unsigned long offset);

#define touch_buffer(bh)        SetPageReferenced(bh->b_page)


#include <linux/pipe_fs_i.h>
#include <linux/minix_fs_i.h>
#include <linux/ext2_fs_i.h>
#include <linux/hpfs_fs_i.h>
#include <linux/ntfs_fs_i.h>
#include <linux/msdos_fs_i.h>
#include <linux/umsdos_fs_i.h>
#include <linux/iso_fs_i.h>
#include <linux/nfs_fs_i.h>
#include <linux/sysv_fs_i.h>
#include <linux/affs_fs_i.h>
#include <linux/ufs_fs_i.h>
#include <linux/efs_fs_i.h>
#include <linux/coda_fs_i.h>
#include <linux/romfs_fs_i.h>
#include <linux/smb_fs_i.h>
#include <linux/hfs_fs_i.h>
#include <linux/adfs_fs_i.h>
#include <linux/qnx4_fs_i.h>
#include <linux/bfs_fs_i.h>
#include <linux/udf_fs_i.h>
#include <linux/ncp_fs_i.h>
#include <linux/proc_fs_i.h>
#include <linux/usbdev_fs_i.h>

/*
 * Attribute flags.  These should be or-ed together to figure out what
 * has been changed!
 */
#define ATTR_MODE       1
#define ATTR_UID        2
#define ATTR_GID        4
#define ATTR_SIZE       8
#define ATTR_ATIME      16
#define ATTR_MTIME      32
#define ATTR_CTIME      64
#define ATTR_ATIME_SET  128
#define ATTR_MTIME_SET  256
#define ATTR_FORCE      512     /* Not a change, but a change it */
#define ATTR_ATTR_FLAG  1024

/*
 * This is the Inode Attributes structure, used for notify_change().  It
 * uses the above definitions as flags, to know which values have changed.
 * Also, in this manner, a Filesystem can look at only the values it cares
 * about.  Basically, these are the attributes that the VFS layer can
 * request to change from the FS layer.
 *
 * Derek Atkins <warlord@MIT.EDU> 94-10-20
 */
struct iattr {
        unsigned int    ia_valid;
        umode_t         ia_mode;
        uid_t           ia_uid;
        gid_t           ia_gid;
        loff_t          ia_size;
        time_t          ia_atime;
        time_t          ia_mtime;
        time_t          ia_ctime;
        unsigned int    ia_attr_flags;
};

/*
 * This is the inode attributes flag definitions
 */
#define ATTR_FLAG_SYNCRONOUS    1       /* Syncronous write */
#define ATTR_FLAG_NOATIME       2       /* Don't update atime */
#define ATTR_FLAG_APPEND        4       /* Append-only file */
#define ATTR_FLAG_IMMUTABLE     8       /* Immutable file */
#define ATTR_FLAG_NODIRATIME    16      /* Don't update atime for directory */

/*
 * Includes for diskquotas and mount structures.
 */
#include <linux/quota.h>
#include <linux/mount.h>

/*
 * oh the beauties of C type declarations.
 */
struct page;
struct address_space;

struct address_space_operations {
        int (*writepage)(struct file *, struct page *);
        int (*readpage)(struct file *, struct page *);
        int (*sync_page)(struct page *);
        int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
        int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
        /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
        int (*bmap)(struct address_space *, long);
};

struct address_space {
        struct list_head        pages;          /* list of pages */
        unsigned long           nrpages;        /* number of pages */
        struct address_space_operations *a_ops; /* methods */
        void                    *host;          /* owner: inode, block_device */
        struct vm_area_struct   *i_mmap;        /* list of mappings */
        spinlock_t              i_shared_lock;  /* and spinlock protecting it */
};

struct block_device {
        struct list_head        bd_hash;
        atomic_t                bd_count;
/*      struct address_space    bd_data; */
        dev_t                   bd_dev;  /* not a kdev_t - it's a search key */
        atomic_t                bd_openers;
        const struct block_device_operations *bd_op;
        struct semaphore        bd_sem; /* open/close mutex */
};

struct inode {
        struct list_head        i_hash;
        struct list_head        i_list;
        struct list_head        i_dentry;

        unsigned long           i_ino;
        atomic_t                i_count;
        kdev_t                  i_dev;
        umode_t                 i_mode;
        nlink_t                 i_nlink;
        uid_t                   i_uid;
        gid_t                   i_gid;
        kdev_t                  i_rdev;
        loff_t                  i_size;
        time_t                  i_atime;
        time_t                  i_mtime;
        time_t                  i_ctime;
        unsigned long           i_blksize;
        unsigned long           i_blocks;
        unsigned long           i_version;
        struct semaphore        i_sem;
        struct semaphore        i_zombie;
        struct inode_operations *i_op;
        struct file_operations  *i_fop; /* former ->i_op->default_file_ops */
        struct super_block      *i_sb;
        wait_queue_head_t       i_wait;
        struct file_lock        *i_flock;
        struct address_space    *i_mapping;
        struct address_space    i_data; 
        struct dquot            *i_dquot[MAXQUOTAS];
        struct pipe_inode_info  *i_pipe;
        struct block_device     *i_bdev;

        unsigned long           i_state;

        unsigned int            i_flags;
        unsigned char           i_sock;

        atomic_t                i_writecount;
        unsigned int            i_attr_flags;
        __u32                   i_generation;
        union {
                struct minix_inode_info         minix_i;
                struct ext2_inode_info          ext2_i;
                struct hpfs_inode_info          hpfs_i;
                struct ntfs_inode_info          ntfs_i;
                struct msdos_inode_info         msdos_i;
                struct umsdos_inode_info        umsdos_i;
                struct iso_inode_info           isofs_i;
                struct nfs_inode_info           nfs_i;
                struct sysv_inode_info          sysv_i;
                struct affs_inode_info          affs_i;
                struct ufs_inode_info           ufs_i;
                struct efs_inode_info           efs_i;
                struct romfs_inode_info         romfs_i;
                struct coda_inode_info          coda_i;
                struct smb_inode_info           smbfs_i;
                struct hfs_inode_info           hfs_i;
                struct adfs_inode_info          adfs_i;
                struct qnx4_inode_info          qnx4_i;
                struct bfs_inode_info           bfs_i;
                struct udf_inode_info           udf_i;
                struct ncp_inode_info           ncpfs_i;
                struct proc_inode_info          proc_i;
                struct socket                   socket_i;
                struct usbdev_inode_info        usbdev_i;
                void                            *generic_ip;
        } u;
};

/* Inode state bits.. */
#define I_DIRTY         1
#define I_LOCK          2
#define I_FREEING       4
#define I_CLEAR         8

extern void __mark_inode_dirty(struct inode *);
static inline void mark_inode_dirty(struct inode *inode)
{
        if (!(inode->i_state & I_DIRTY))
                __mark_inode_dirty(inode);
}

struct fown_struct {
        int pid;                /* pid or -pgrp where SIGIO should be sent */
        uid_t uid, euid;        /* uid/euid of process setting the owner */
        int signum;             /* posix.1b rt signal to be delivered on IO */
};

struct file {
        struct list_head        f_list;
        struct dentry           *f_dentry;
        struct vfsmount         *f_vfsmnt;
        struct file_operations  *f_op;
        atomic_t                f_count;
        unsigned int            f_flags;
        mode_t                  f_mode;
        loff_t                  f_pos;
        unsigned long           f_reada, f_ramax, f_raend, f_ralen, f_rawin;
        struct fown_struct      f_owner;
        unsigned int            f_uid, f_gid;
        int                     f_error;

        unsigned long           f_version;

        /* needed for tty driver, and maybe others */
        void                    *private_data;
};
extern spinlock_t files_lock;
#define file_list_lock() spin_lock(&files_lock);
#define file_list_unlock() spin_unlock(&files_lock);

#define get_file(x)     atomic_inc(&(x)->f_count)
#define file_count(x)   atomic_read(&(x)->f_count)

extern int init_private_file(struct file *, struct dentry *, int);

#define FL_POSIX        1
#define FL_FLOCK        2
#define FL_BROKEN       4       /* broken flock() emulation */
#define FL_ACCESS       8       /* for processes suspended by mandatory locking */
#define FL_LOCKD        16      /* lock held by rpc.lockd */

/*
 * The POSIX file lock owner is determined by
 * the "struct files_struct" in the thread group
 * (or NULL for no owner - BSD locks).
 *
 * Lockd stuffs a "host" pointer into this.
 */
typedef struct files_struct *fl_owner_t;

struct file_lock {
        struct file_lock *fl_next;      /* singly linked list for this inode  */
        struct list_head fl_link;       /* doubly linked list of all locks */
        struct list_head fl_block; /* circular list of blocked processes */
        fl_owner_t fl_owner;
        unsigned int fl_pid;
        wait_queue_head_t fl_wait;
        struct file *fl_file;
        unsigned char fl_flags;
        unsigned char fl_type;
        loff_t fl_start;
        loff_t fl_end;

        void (*fl_notify)(struct file_lock *);  /* unblock callback */
        void (*fl_insert)(struct file_lock *);  /* lock insertion callback */
        void (*fl_remove)(struct file_lock *);  /* lock removal callback */

        union {
                struct nfs_lock_info    nfs_fl;
        } fl_u;
};

/* The following constant reflects the upper bound of the file/locking space */
#ifndef OFFSET_MAX
#define INT_LIMIT(x)    (~((x)1 << (sizeof(x)*8 - 1)))
#define OFFSET_MAX      INT_LIMIT(loff_t)
#endif

extern struct list_head file_lock_list;

#include <linux/fcntl.h>

extern int fcntl_getlk(unsigned int, struct flock *);
extern int fcntl_setlk(unsigned int, unsigned int, struct flock *);

/* fs/locks.c */
extern void locks_remove_posix(struct file *, fl_owner_t);
extern void locks_remove_flock(struct file *);
extern struct file_lock *posix_test_lock(struct file *, struct file_lock *);
extern int posix_lock_file(struct file *, struct file_lock *, unsigned int);
extern void posix_block_lock(struct file_lock *, struct file_lock *);
extern void posix_unblock_lock(struct file_lock *);

struct fasync_struct {
        int     magic;
        int     fa_fd;
        struct  fasync_struct   *fa_next; /* singly linked list */
        struct  file            *fa_file;
};

#define FASYNC_MAGIC 0x4601

/* SMP safe fasync helpers: */
extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
/* can be called from interrupts */
extern void kill_fasync(struct fasync_struct **, int, int);
/* only for net: no internal synchronization */
extern void __kill_fasync(struct fasync_struct *, int, int);

struct nameidata {
        struct dentry *dentry;
        struct vfsmount *mnt;
        struct qstr last;
        unsigned int flags;
        int last_type;
};

#define DQUOT_USR_ENABLED       0x01            /* User diskquotas enabled */
#define DQUOT_GRP_ENABLED       0x02            /* Group diskquotas enabled */

struct quota_mount_options
{
        unsigned int flags;                     /* Flags for diskquotas on this device */
        struct semaphore dqio_sem;              /* lock device while I/O in progress */
        struct semaphore dqoff_sem;             /* serialize quota_off() and quota_on() on device */
        struct file *files[MAXQUOTAS];          /* fp's to quotafiles */
        time_t inode_expire[MAXQUOTAS];         /* expiretime for inode-quota */
        time_t block_expire[MAXQUOTAS];         /* expiretime for block-quota */
        char rsquash[MAXQUOTAS];                /* for quotas threat root as any other user */
};

/*
 *      Umount options
 */

#define MNT_FORCE       0x00000001      /* Attempt to forcibily umount */

#include <linux/minix_fs_sb.h>
#include <linux/ext2_fs_sb.h>
#include <linux/hpfs_fs_sb.h>
#include <linux/ntfs_fs_sb.h>
#include <linux/msdos_fs_sb.h>
#include <linux/iso_fs_sb.h>
#include <linux/nfs_fs_sb.h>
#include <linux/sysv_fs_sb.h>
#include <linux/affs_fs_sb.h>
#include <linux/ufs_fs_sb.h>
#include <linux/efs_fs_sb.h>
#include <linux/romfs_fs_sb.h>
#include <linux/smb_fs_sb.h>
#include <linux/hfs_fs_sb.h>
#include <linux/adfs_fs_sb.h>
#include <linux/qnx4_fs_sb.h>
#include <linux/bfs_fs_sb.h>
#include <linux/udf_fs_sb.h>
#include <linux/ncp_fs_sb.h>
#include <linux/usbdev_fs_sb.h>

extern struct list_head super_blocks;

#define sb_entry(list)  list_entry((list), struct super_block, s_list)
struct super_block {
        struct list_head        s_list;         /* Keep this first */
        kdev_t                  s_dev;
        unsigned long           s_blocksize;
        unsigned char           s_blocksize_bits;
        unsigned char           s_lock;
        unsigned char           s_dirt;
        struct file_system_type *s_type;
        struct super_operations *s_op;
        struct dquot_operations *dq_op;
        unsigned long           s_flags;
        unsigned long           s_magic;
        struct dentry           *s_root;
        wait_queue_head_t       s_wait;

        struct list_head        s_dirty;        /* dirty inodes */
        struct list_head        s_files;

        struct block_device     *s_bdev;
        struct list_head        s_mounts;       /* vfsmount(s) of this one */
        struct quota_mount_options s_dquot;     /* Diskquota specific options */

        union {
                struct minix_sb_info    minix_sb;
                struct ext2_sb_info     ext2_sb;
                struct hpfs_sb_info     hpfs_sb;
                struct ntfs_sb_info     ntfs_sb;
                struct msdos_sb_info    msdos_sb;
                struct isofs_sb_info    isofs_sb;
                struct nfs_sb_info      nfs_sb;
                struct sysv_sb_info     sysv_sb;
                struct affs_sb_info     affs_sb;
                struct ufs_sb_info      ufs_sb;
                struct efs_sb_info      efs_sb;
                struct romfs_sb_info    romfs_sb;
                struct smb_sb_info      smbfs_sb;
                struct hfs_sb_info      hfs_sb;
                struct adfs_sb_info     adfs_sb;
                struct qnx4_sb_info     qnx4_sb;
                struct bfs_sb_info      bfs_sb;
                struct udf_sb_info      udf_sb;
                struct ncp_sb_info      ncpfs_sb;
                struct usbdev_sb_info   usbdevfs_sb;
                void                    *generic_sbp;
        } u;
        /*
         * The next field is for VFS *only*. No filesystems have any business
         * even looking at it. You had been warned.
         */
        struct semaphore s_vfs_rename_sem;      /* Kludge */

        /* The next field is used by knfsd when converting a (inode number based)
         * file handle into a dentry. As it builds a path in the dcache tree from
         * the bottom up, there may for a time be a subpath of dentrys which is not
         * connected to the main tree.  This semaphore ensure that there is only ever
         * one such free path per filesystem.  Note that unconnected files (or other
         * non-directories) are allowed, but not unconnected diretories.
         */
        struct semaphore s_nfsd_free_path_sem;
};

/*
 * VFS helper functions..
 */
extern int vfs_create(struct inode *, struct dentry *, int);
extern int vfs_mkdir(struct inode *, struct dentry *, int);
extern int vfs_mknod(struct inode *, struct dentry *, int, dev_t);
extern int vfs_symlink(struct inode *, struct dentry *, const char *);
extern int vfs_link(struct dentry *, struct inode *, struct dentry *);
extern int vfs_rmdir(struct inode *, struct dentry *);
extern int vfs_unlink(struct inode *, struct dentry *);
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);

/*
 * This is the "filldir" function type, used by readdir() to let
 * the kernel specify what kind of dirent layout it wants to have.
 * This allows the kernel to read directories into kernel space or
 * to have different dirent layouts depending on the binary type.
 */
typedef int (*filldir_t)(void *, const char *, int, off_t, ino_t);

struct block_device_operations {
        int (*open) (struct inode *, struct file *);
        int (*release) (struct inode *, struct file *);
        int (*ioctl) (struct inode *, struct file *, unsigned, unsigned long);
        int (*check_media_change) (kdev_t);
        int (*revalidate) (kdev_t);
};

/*
 * NOTE:
 * read, write, poll, fsync, readv, writev can be called
 *   without the big kernel lock held in all filesystems.
 */
struct file_operations {
        struct module *owner;
        loff_t (*llseek) (struct file *, loff_t, int);
        ssize_t (*read) (struct file *, char *, size_t, loff_t *);
        ssize_t (*write) (struct file *, const char *, size_t, loff_t *);
        int (*readdir) (struct file *, void *, filldir_t);
        unsigned int (*poll) (struct file *, struct poll_table_struct *);
        int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
        int (*mmap) (struct file *, struct vm_area_struct *);
        int (*open) (struct inode *, struct file *);
        int (*flush) (struct file *);
        int (*release) (struct inode *, struct file *);
        int (*fsync) (struct file *, struct dentry *, int datasync);
        int (*fasync) (int, struct file *, int);
        int (*lock) (struct file *, int, struct file_lock *);
        ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
        ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
};

struct inode_operations {
        int (*create) (struct inode *,struct dentry *,int);
        struct dentry * (*lookup) (struct inode *,struct dentry *);
        int (*link) (struct dentry *,struct inode *,struct dentry *);
        int (*unlink) (struct inode *,struct dentry *);
        int (*symlink) (struct inode *,struct dentry *,const char *);
        int (*mkdir) (struct inode *,struct dentry *,int);
        int (*rmdir) (struct inode *,struct dentry *);
        int (*mknod) (struct inode *,struct dentry *,int,int);
        int (*rename) (struct inode *, struct dentry *,
                        struct inode *, struct dentry *);
        int (*readlink) (struct dentry *, char *,int);
        int (*follow_link) (struct dentry *, struct nameidata *);
        void (*truncate) (struct inode *);
        int (*permission) (struct inode *, int);
        int (*revalidate) (struct dentry *);
        int (*setattr) (struct dentry *, struct iattr *);
        int (*getattr) (struct dentry *, struct iattr *);
};

/*
 * NOTE: write_inode, delete_inode, clear_inode, put_inode can be called
 * without the big kernel lock held in all filesystems.
 */
struct super_operations {
        void (*read_inode) (struct inode *);
        void (*write_inode) (struct inode *, int);
        void (*put_inode) (struct inode *);
        void (*delete_inode) (struct inode *);
        void (*put_super) (struct super_block *);
        void (*write_super) (struct super_block *);
        int (*statfs) (struct super_block *, struct statfs *);
        int (*remount_fs) (struct super_block *, int *, char *);
        void (*clear_inode) (struct inode *);
        void (*umount_begin) (struct super_block *);
};

struct dquot_operations {
        void (*initialize) (struct inode *, short);
        void (*drop) (struct inode *);
        int (*alloc_block) (const struct inode *, unsigned long, char);
        int (*alloc_inode) (const struct inode *, unsigned long);
        void (*free_block) (const struct inode *, unsigned long);
        void (*free_inode) (const struct inode *, unsigned long);
        int (*transfer) (struct dentry *, struct iattr *);
};

struct file_system_type {
        const char *name;
        int fs_flags;
        struct super_block *(*read_super) (struct super_block *, void *, int);
        struct module *owner;
        struct vfsmount *kern_mnt; /* For kernel mount, if it's FS_SINGLE fs */
        struct file_system_type * next;
};

#define DECLARE_FSTYPE(var,type,read,flags) \
struct file_system_type var = { \
        name:           type, \
        read_super:     read, \
        fs_flags:       flags, \
        owner:          THIS_MODULE, \
}

#define DECLARE_FSTYPE_DEV(var,type,read) \
        DECLARE_FSTYPE(var,type,read,FS_REQUIRES_DEV)

/* Alas, no aliases. Too much hassle with bringing module.h everywhere */
#define fops_get(fops) \
        (((fops) && (fops)->owner)      \
                ? __MOD_INC_USE_COUNT((fops)->owner), (fops) \
                : (fops))

#define fops_put(fops) \
do {    \
        if ((fops) && (fops)->owner) \
                __MOD_DEC_USE_COUNT((fops)->owner);     \
} while(0)

extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
extern struct vfsmount *kern_mount(struct file_system_type *);
extern void kern_umount(struct vfsmount *);
extern int may_umount(struct vfsmount *);
extern long do_mount(char *, char *, char *, unsigned long, void *);


extern int vfs_statfs(struct super_block *, struct statfs *);

/* Return value for VFS lock functions - tells locks.c to lock conventionally
 * REALLY kosha for root NFS and nfs_lock
 */ 
#define LOCK_USE_CLNT 1

#define FLOCK_VERIFY_READ  1
#define FLOCK_VERIFY_WRITE 2

extern int locks_mandatory_locked(struct inode *);
extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);

/*
 * Candidates for mandatory locking have the setgid bit set
 * but no group execute bit -  an otherwise meaningless combination.
 */
#define MANDATORY_LOCK(inode) \
        (IS_MANDLOCK(inode) && ((inode)->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)

static inline int locks_verify_locked(struct inode *inode)
{
        if (MANDATORY_LOCK(inode))
                return locks_mandatory_locked(inode);
        return 0;
}

static inline int locks_verify_area(int read_write, struct inode *inode,
                                    struct file *filp, loff_t offset,
                                    size_t count)
{
        if (inode->i_flock && MANDATORY_LOCK(inode))
                return locks_mandatory_area(read_write, inode, filp, offset, count);
        return 0;
}

static inline int locks_verify_truncate(struct inode *inode,
                                    struct file *filp,
                                    loff_t size)
{
        if (inode->i_flock && MANDATORY_LOCK(inode))
                return locks_mandatory_area(
                        FLOCK_VERIFY_WRITE, inode, filp,
                        size < inode->i_size ? size : inode->i_size,
                        (size < inode->i_size ? inode->i_size - size
                         : size - inode->i_size)
                );
        return 0;
}


/* fs/open.c */

asmlinkage long sys_open(const char *, int, int);
asmlinkage long sys_close(unsigned int);        /* yes, it's really unsigned */
extern int do_close(unsigned int, int);         /* yes, it's really unsigned */
extern int do_truncate(struct dentry *, loff_t start);

extern struct file *filp_open(const char *, int, int);
extern struct file * dentry_open(struct dentry *, struct vfsmount *, int);
extern int filp_close(struct file *, fl_owner_t id);
extern char * getname(const char *);
#define __getname()     ((char *) __get_free_page(GFP_KERNEL))
#define putname(name)   free_page((unsigned long)(name))

enum {BDEV_FILE, BDEV_SWAP, BDEV_FS, BDEV_RAW};
extern int register_blkdev(unsigned int, const char *, struct block_device_operations *);
extern int unregister_blkdev(unsigned int, const char *);
extern struct block_device *bdget(dev_t);
extern void bdput(struct block_device *);
extern int blkdev_open(struct inode *, struct file *);
extern struct file_operations def_blk_fops;
extern struct file_operations def_fifo_fops;
extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
extern int blkdev_get(struct block_device *, mode_t, unsigned, int);
extern int blkdev_put(struct block_device *, int);

/* fs/devices.c */
extern const struct block_device_operations *get_blkfops(unsigned int);
extern struct file_operations *get_chrfops(unsigned int, unsigned int);
extern int register_chrdev(unsigned int, const char *, struct file_operations *);
extern int unregister_chrdev(unsigned int, const char *);
extern int chrdev_open(struct inode *, struct file *);
extern const char * bdevname(kdev_t);
extern const char * cdevname(kdev_t);
extern const char * kdevname(kdev_t);
extern void init_special_inode(struct inode *, umode_t, int);

/* Invalid inode operations -- fs/bad_inode.c */
extern void make_bad_inode(struct inode *);
extern int is_bad_inode(struct inode *);

extern struct file_operations read_fifo_fops;
extern struct file_operations write_fifo_fops;
extern struct file_operations rdwr_fifo_fops;
extern struct file_operations read_pipe_fops;
extern struct file_operations write_pipe_fops;
extern struct file_operations rdwr_pipe_fops;

extern int fs_may_remount_ro(struct super_block *);

extern int try_to_free_buffers(struct page *, int);
extern void refile_buffer(struct buffer_head * buf);

#define BUF_CLEAN       0
#define BUF_LOCKED      1       /* Buffers scheduled for write */
#define BUF_DIRTY       2       /* Dirty buffers, not yet scheduled for write */
#define BUF_PROTECTED   3       /* Ramdisk persistent storage */
#define NR_LIST         4

/*
 * This is called by bh->b_end_io() handlers when I/O has completed.
 */
static inline void mark_buffer_uptodate(struct buffer_head * bh, int on)
{
        if (on)
                set_bit(BH_Uptodate, &bh->b_state);
        else
                clear_bit(BH_Uptodate, &bh->b_state);
}

#define atomic_set_buffer_clean(bh) test_and_clear_bit(BH_Dirty, &(bh)->b_state)

static inline void __mark_buffer_clean(struct buffer_head *bh)
{
        refile_buffer(bh);
}

static inline void mark_buffer_clean(struct buffer_head * bh)
{
        if (atomic_set_buffer_clean(bh))
                __mark_buffer_clean(bh);
}

#define atomic_set_buffer_protected(bh) test_and_set_bit(BH_Protected, &(bh)->b_state)

static inline void __mark_buffer_protected(struct buffer_head *bh)
{
        refile_buffer(bh);
}

static inline void mark_buffer_protected(struct buffer_head * bh)
{
        if (!atomic_set_buffer_protected(bh))
                __mark_buffer_protected(bh);
}

extern void FASTCALL(__mark_buffer_dirty(struct buffer_head *bh, int flag));
extern void FASTCALL(mark_buffer_dirty(struct buffer_head *bh, int flag));

#define atomic_set_buffer_dirty(bh) test_and_set_bit(BH_Dirty, &(bh)->b_state)

/*
 * If an error happens during the make_request, this function
 * has to be recalled. It marks the buffer as clean and not
 * uptodate, and it notifys the upper layer about the end
 * of the I/O.
 */
static inline void buffer_IO_error(struct buffer_head * bh)
{
        mark_buffer_clean(bh);
        /*
         * b_end_io has to clear the BH_Uptodate bitflag in the error case!
         */
        bh->b_end_io(bh, 0);
}

extern void balance_dirty(kdev_t);
extern int check_disk_change(kdev_t);
extern int invalidate_inodes(struct super_block *);
extern void invalidate_inode_pages(struct inode *);
#define invalidate_buffers(dev) __invalidate_buffers((dev), 0)
#define destroy_buffers(dev)    __invalidate_buffers((dev), 1)
extern void __invalidate_buffers(kdev_t dev, int);
extern void sync_inodes(kdev_t);
extern void write_inode_now(struct inode *, int);
extern void sync_dev(kdev_t);
extern int fsync_dev(kdev_t);
extern void sync_supers(kdev_t);
extern int bmap(struct inode *, int);
extern int notify_change(struct dentry *, struct iattr *);
extern int permission(struct inode *, int);
extern int get_write_access(struct inode *);
extern int deny_write_access(struct file *);
static inline void put_write_access(struct inode * inode)
{
        atomic_dec(&inode->i_writecount);
}
static inline void allow_write_access(struct file *file)
{
        if (file)
                atomic_inc(&file->f_dentry->d_inode->i_writecount);
}
extern int do_pipe(int *);

extern int open_namei(const char *, int, int, struct nameidata *);

extern int kernel_read(struct file *, unsigned long, char *, unsigned long);
extern struct file * open_exec(const char *);
 
/* fs/dcache.c -- generic fs support functions */
extern int is_subdir(struct dentry *, struct dentry *);
extern ino_t find_inode_number(struct dentry *, struct qstr *);

/*
 * Kernel pointers have redundant information, so we can use a
 * scheme where we can return either an error code or a dentry
 * pointer with the same return value.
 *
 * This should be a per-architecture thing, to allow different
 * error and pointer decisions.
 */
#define ERR_PTR(err)    ((void *)((long)(err)))
#define PTR_ERR(ptr)    ((long)(ptr))
#define IS_ERR(ptr)     ((unsigned long)(ptr) > (unsigned long)(-1000))

/*
 * The bitmask for a lookup event:
 *  - follow links at the end
 *  - require a directory
 *  - ending slashes ok even for nonexistent files
 *  - internal "there are more path compnents" flag
 */
#define LOOKUP_FOLLOW           (1)
#define LOOKUP_DIRECTORY        (2)
#define LOOKUP_CONTINUE         (4)
#define LOOKUP_POSITIVE         (8)
#define LOOKUP_PARENT           (16)
#define LOOKUP_NOALT            (32)
/*
 * Type of the last component on LOOKUP_PARENT
 */
enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};

/*
 * "descriptor" for what we're up to with a read for sendfile().
 * This allows us to use the same read code yet
 * have multiple different users of the data that
 * we read from a file.
 *
 * The simplest case just copies the data to user
 * mode.
 */
typedef struct {
        size_t written;
        size_t count;
        char * buf;
        int error;
} read_descriptor_t;

typedef int (*read_actor_t)(read_descriptor_t *, struct page *, unsigned long, unsigned long);

/* needed for stackable file system support */
extern loff_t default_llseek(struct file *file, loff_t offset, int origin);

extern int __user_walk(const char *, unsigned, struct nameidata *);
extern int path_init(const char *, unsigned, struct nameidata *);
extern int path_walk(const char *, struct nameidata *);
extern void path_release(struct nameidata *);
extern int follow_down(struct vfsmount **, struct dentry **);
extern int follow_up(struct vfsmount **, struct dentry **);
extern struct dentry * lookup_one(const char *, struct dentry *);
extern struct dentry * lookup_hash(struct qstr *, struct dentry *);
#define user_path_walk(name,nd)  __user_walk(name, LOOKUP_FOLLOW|LOOKUP_POSITIVE, nd)
#define user_path_walk_link(name,nd) __user_walk(name, LOOKUP_POSITIVE, nd)

extern void iput(struct inode *);
extern void force_delete(struct inode *);
extern struct inode * igrab(struct inode *);
extern ino_t iunique(struct super_block *, ino_t);

typedef int (*find_inode_t)(struct inode *, unsigned long, void *);
extern struct inode * iget4(struct super_block *, unsigned long, find_inode_t, void *);
static inline struct inode *iget(struct super_block *sb, unsigned long ino)
{
        return iget4(sb, ino, NULL, NULL);
}

extern void clear_inode(struct inode *);
extern struct inode * get_empty_inode(void);

extern void insert_inode_hash(struct inode *);
extern void remove_inode_hash(struct inode *);
extern struct file * get_empty_filp(void);
extern void file_move(struct file *f, struct list_head *list);
extern void file_moveto(struct file *new, struct file *old);
extern struct buffer_head * get_hash_table(kdev_t, int, int);
extern struct buffer_head * getblk(kdev_t, int, int);
extern void ll_rw_block(int, int, struct buffer_head * bh[]);
extern int is_read_only(kdev_t);
extern void __brelse(struct buffer_head *);
static inline void brelse(struct buffer_head *buf)
{
        if (buf)
                __brelse(buf);
}
extern void __bforget(struct buffer_head *);
static inline void bforget(struct buffer_head *buf)
{
        if (buf)
                __bforget(buf);
}
extern void set_blocksize(kdev_t, int);
extern unsigned int get_hardblocksize(kdev_t);
extern struct buffer_head * bread(kdev_t, int, int);
extern struct buffer_head * breada(kdev_t, int, int, unsigned int, unsigned int);
extern void wakeup_bdflush(int wait);

extern int brw_page(int, struct page *, kdev_t, int [], int);

typedef int (get_block_t)(struct inode*,long,struct buffer_head*,int);

/* Generic buffer handling for block filesystems.. */
extern int block_flushpage(struct page *, unsigned long);
extern int block_symlink(struct inode *, const char *, int);
extern int block_write_full_page(struct page*, get_block_t*);
extern int block_read_full_page(struct page*, get_block_t*);
extern int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
extern int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
                                unsigned long *);
extern int block_sync_page(struct page *);

int generic_block_bmap(struct address_space *, long, get_block_t *);
int generic_commit_write(struct file *, struct page *, unsigned, unsigned);

extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern ssize_t generic_file_read(struct file *, char *, size_t, loff_t *);
extern ssize_t generic_file_write(struct file *, const char *, size_t, loff_t *);
extern void do_generic_file_read(struct file *, loff_t *, read_descriptor_t *, read_actor_t);

extern ssize_t generic_read_dir(struct file *, char *, size_t, loff_t *);

extern struct file_operations generic_ro_fops;

extern int vfs_readlink(struct dentry *, char *, int, const char *);
extern int vfs_follow_link(struct nameidata *, const char *);
extern int page_readlink(struct dentry *, char *, int);
extern int page_follow_link(struct dentry *, struct nameidata *);
extern struct inode_operations page_symlink_inode_operations;

extern int vfs_readdir(struct file *, filldir_t, void *);
extern int dcache_readdir(struct file *, void *, filldir_t);

extern struct file_system_type *get_fs_type(const char *name);
extern struct super_block *get_super(kdev_t);
struct super_block *get_empty_super(void);
extern void put_super(kdev_t);
unsigned long generate_cluster(kdev_t, int b[], int);
unsigned long generate_cluster_swab32(kdev_t, int b[], int);
extern kdev_t ROOT_DEV;
extern char root_device_name[];


extern void show_buffers(void);
extern void mount_root(void);

#ifdef CONFIG_BLK_DEV_INITRD
extern kdev_t real_root_dev;
extern int change_root(kdev_t, const char *);
#endif

extern ssize_t char_read(struct file *, char *, size_t, loff_t *);
extern ssize_t block_read(struct file *, char *, size_t, loff_t *);
extern int read_ahead[];

extern ssize_t char_write(struct file *, const char *, size_t, loff_t *);
extern ssize_t block_write(struct file *, const char *, size_t, loff_t *);

extern int file_fsync(struct file *, struct dentry *, int);
extern int generic_buffer_fdatasync(struct inode *inode, unsigned long start_idx, unsigned long end_idx);

extern int inode_change_ok(struct inode *, struct iattr *);
extern void inode_setattr(struct inode *, struct iattr *);

/*
 * Common dentry functions for inclusion in the VFS
 * or in other stackable file systems.  Some of these
 * functions were in linux/fs/ C (VFS) files.
 *
 */

/*
 * Locking the parent is needed to:
 *  - serialize directory operations
 *  - make sure the parent doesn't change from
 *    under us in the middle of an operation.
 *
 * NOTE! Right now we'd rather use a "struct inode"
 * for this, but as I expect things to move toward
 * using dentries instead for most things it is
 * probably better to start with the conceptually
 * better interface of relying on a path of dentries.
 */
static inline struct dentry *lock_parent(struct dentry *dentry)
{
        struct dentry *dir = dget(dentry->d_parent);

        down(&dir->d_inode->i_sem);
        return dir;
}

static inline struct dentry *get_parent(struct dentry *dentry)
{
        return dget(dentry->d_parent);
}

static inline void unlock_dir(struct dentry *dir)
{
        up(&dir->d_inode->i_sem);
        dput(dir);
}

/*
 * Whee.. Deadlock country. Happily there are only two VFS
 * operations that does this..
 */
static inline void double_down(struct semaphore *s1, struct semaphore *s2)
{
        if (s1 != s2) {
                if ((unsigned long) s1 < (unsigned long) s2) {
                        struct semaphore *tmp = s2;
                        s2 = s1; s1 = tmp;
                }
                down(s1);
        }
        down(s2);
}

/*
 * Ewwwwwwww... _triple_ lock. We are guaranteed that the 3rd argument is
 * not equal to 1st and not equal to 2nd - the first case (target is parent of
 * source) would be already caught, the second is plain impossible (target is
 * its own parent and that case would be caught even earlier). Very messy.
 * I _think_ that it works, but no warranties - please, look it through.
 * Pox on bloody lusers who mandated overwriting rename() for directories...
 */

static inline void triple_down(struct semaphore *s1,
                               struct semaphore *s2,
                               struct semaphore *s3)
{
        if (s1 != s2) {
                if ((unsigned long) s1 < (unsigned long) s2) {
                        if ((unsigned long) s1 < (unsigned long) s3) {
                                struct semaphore *tmp = s3;
                                s3 = s1; s1 = tmp;
                        }
                        if ((unsigned long) s1 < (unsigned long) s2) {
                                struct semaphore *tmp = s2;
                                s2 = s1; s1 = tmp;
                        }
                } else {
                        if ((unsigned long) s1 < (unsigned long) s3) {
                                struct semaphore *tmp = s3;
                                s3 = s1; s1 = tmp;
                        }
                        if ((unsigned long) s2 < (unsigned long) s3) {
                                struct semaphore *tmp = s3;
                                s3 = s2; s2 = tmp;
                        }
                }
                down(s1);
        } else if ((unsigned long) s2 < (unsigned long) s3) {
                struct semaphore *tmp = s3;
                s3 = s2; s2 = tmp;
        }
        down(s2);
        down(s3);
}

static inline void double_up(struct semaphore *s1, struct semaphore *s2)
{
        up(s1);
        if (s1 != s2)
                up(s2);
}

static inline void triple_up(struct semaphore *s1,
                             struct semaphore *s2,
                             struct semaphore *s3)
{
        up(s1);
        if (s1 != s2)
                up(s2);
        up(s3);
}

static inline void double_lock(struct dentry *d1, struct dentry *d2)
{
        double_down(&d1->d_inode->i_sem, &d2->d_inode->i_sem);
}

static inline void double_unlock(struct dentry *d1, struct dentry *d2)
{
        double_up(&d1->d_inode->i_sem,&d2->d_inode->i_sem);
        dput(d1);
        dput(d2);
}

#endif /* __KERNEL__ */

#endif /* _LINUX_FS_H */