fs.h

Go to the documentation of this file.

#ifndef _LINUX_FS_H
#define _LINUX_FS_H


#include <linux/linkage.h>
#include <linux/wait.h>
#include <linux/kdev_t.h>
#include <linux/dcache.h>
#include <linux/path.h>
#include <linux/stat.h>
#include <linux/cache.h>
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/pid.h>
#include <linux/bug.h>
#include <linux/mutex.h>
#include <linux/capability.h>
#include <linux/semaphore.h>
#include <linux/fiemap.h>
#include <linux/rculist_bl.h>
#include <linux/atomic.h>
#include <linux/shrinker.h>
#include <linux/migrate_mode.h>
#include <linux/uidgid.h>
#include <linux/lockdep.h>
#include <linux/percpu-rwsem.h>
#include <linux/blk_types.h>

#include <asm/byteorder.h>
#include <uapi/linux/fs.h>

struct export_operations;
struct hd_geometry;
struct iovec;
struct nameidata;
struct kiocb;
struct kobject;
struct pipe_inode_info;
struct poll_table_struct;
struct kstatfs;
struct vm_area_struct;
struct vfsmount;
struct cred;
struct swap_info_struct;

extern void __init inode_init(void);
extern void __init inode_init_early(void);
extern void __init files_init(unsigned long);

extern struct files_stat_struct files_stat;
extern unsigned long get_max_files(void);
extern int sysctl_nr_open;
extern struct inodes_stat_t inodes_stat;
extern int leases_enable, lease_break_time;
extern int sysctl_protected_symlinks;
extern int sysctl_protected_hardlinks;

struct buffer_head;
typedef int (get_block_t)(struct inode *inode, sector_t iblock,
            struct buffer_head *bh_result, int create);
typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
            ssize_t bytes, void *private, int ret,
            bool is_async);

#define MAY_EXEC        0x00000001
#define MAY_WRITE       0x00000002
#define MAY_READ        0x00000004
#define MAY_APPEND      0x00000008
#define MAY_ACCESS      0x00000010
#define MAY_OPEN        0x00000020
#define MAY_CHDIR       0x00000040
/* called from RCU mode, don't block */
#define MAY_NOT_BLOCK       0x00000080

/*
 * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
 * to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
 */

/* file is open for reading */
#define FMODE_READ      ((__force fmode_t)0x1)
/* file is open for writing */
#define FMODE_WRITE     ((__force fmode_t)0x2)
/* file is seekable */
#define FMODE_LSEEK     ((__force fmode_t)0x4)
/* file can be accessed using pread */
#define FMODE_PREAD     ((__force fmode_t)0x8)
/* file can be accessed using pwrite */
#define FMODE_PWRITE        ((__force fmode_t)0x10)
/* File is opened for execution with sys_execve / sys_uselib */
#define FMODE_EXEC      ((__force fmode_t)0x20)
/* File is opened with O_NDELAY (only set for block devices) */
#define FMODE_NDELAY        ((__force fmode_t)0x40)
/* File is opened with O_EXCL (only set for block devices) */
#define FMODE_EXCL      ((__force fmode_t)0x80)
/* File is opened using open(.., 3, ..) and is writeable only for ioctls
   (specialy hack for floppy.c) */
#define FMODE_WRITE_IOCTL   ((__force fmode_t)0x100)
/* 32bit hashes as llseek() offset (for directories) */
#define FMODE_32BITHASH         ((__force fmode_t)0x200)
/* 64bit hashes as llseek() offset (for directories) */
#define FMODE_64BITHASH         ((__force fmode_t)0x400)

/*
 * Don't update ctime and mtime.
 *
 * Currently a special hack for the XFS open_by_handle ioctl, but we'll
 * hopefully graduate it to a proper O_CMTIME flag supported by open(2) soon.
 */
#define FMODE_NOCMTIME      ((__force fmode_t)0x800)

/* Expect random access pattern */
#define FMODE_RANDOM        ((__force fmode_t)0x1000)

/* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
#define FMODE_UNSIGNED_OFFSET   ((__force fmode_t)0x2000)

/* File is opened with O_PATH; almost nothing can be done with it */
#define FMODE_PATH      ((__force fmode_t)0x4000)

/* File was opened by fanotify and shouldn't generate fanotify events */
#define FMODE_NONOTIFY      ((__force fmode_t)0x1000000)

/*
 * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
 * that indicates that they should check the contents of the iovec are
 * valid, but not check the memory that the iovec elements
 * points too.
 */
#define CHECK_IOVEC_ONLY -1

/*
 * The below are the various read and write types that we support. Some of
 * them include behavioral modifiers that send information down to the
 * block layer and IO scheduler. Terminology:
 *
 *  The block layer uses device plugging to defer IO a little bit, in
 *  the hope that we will see more IO very shortly. This increases
 *  coalescing of adjacent IO and thus reduces the number of IOs we
 *  have to send to the device. It also allows for better queuing,
 *  if the IO isn't mergeable. If the caller is going to be waiting
 *  for the IO, then he must ensure that the device is unplugged so
 *  that the IO is dispatched to the driver.
 *
 *  All IO is handled async in Linux. This is fine for background
 *  writes, but for reads or writes that someone waits for completion
 *  on, we want to notify the block layer and IO scheduler so that they
 *  know about it. That allows them to make better scheduling
 *  decisions. So when the below references 'sync' and 'async', it
 *  is referencing this priority hint.
 *
 * With that in mind, the available types are:
 *
 * READ         A normal read operation. Device will be plugged.
 * READ_SYNC        A synchronous read. Device is not plugged, caller can
 *          immediately wait on this read without caring about
 *          unplugging.
 * READA        Used for read-ahead operations. Lower priority, and the
 *          block layer could (in theory) choose to ignore this
 *          request if it runs into resource problems.
 * WRITE        A normal async write. Device will be plugged.
 * WRITE_SYNC       Synchronous write. Identical to WRITE, but passes down
 *          the hint that someone will be waiting on this IO
 *          shortly. The write equivalent of READ_SYNC.
 * WRITE_ODIRECT    Special case write for O_DIRECT only.
 * WRITE_FLUSH      Like WRITE_SYNC but with preceding cache flush.
 * WRITE_FUA        Like WRITE_SYNC but data is guaranteed to be on
 *          non-volatile media on completion.
 * WRITE_FLUSH_FUA  Combination of WRITE_FLUSH and FUA. The IO is preceded
 *          by a cache flush and data is guaranteed to be on
 *          non-volatile media on completion.
 *
 */
#define RW_MASK         REQ_WRITE
#define RWA_MASK        REQ_RAHEAD

#define READ            0
#define WRITE           RW_MASK
#define READA           RWA_MASK
#define KERNEL_READ     (READ|REQ_KERNEL)
#define KERNEL_WRITE        (WRITE|REQ_KERNEL)

#define READ_SYNC       (READ | REQ_SYNC)
#define WRITE_SYNC      (WRITE | REQ_SYNC | REQ_NOIDLE)
#define WRITE_ODIRECT       (WRITE | REQ_SYNC)
#define WRITE_FLUSH     (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH)
#define WRITE_FUA       (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FUA)
#define WRITE_FLUSH_FUA     (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)

/*
 * Attribute flags.  These should be or-ed together to figure out what
 * has been changed!
 */
#define ATTR_MODE   (1 << 0)
#define ATTR_UID    (1 << 1)
#define ATTR_GID    (1 << 2)
#define ATTR_SIZE   (1 << 3)
#define ATTR_ATIME  (1 << 4)
#define ATTR_MTIME  (1 << 5)
#define ATTR_CTIME  (1 << 6)
#define ATTR_ATIME_SET  (1 << 7)
#define ATTR_MTIME_SET  (1 << 8)
#define ATTR_FORCE  (1 << 9) /* Not a change, but a change it */
#define ATTR_ATTR_FLAG  (1 << 10)
#define ATTR_KILL_SUID  (1 << 11)
#define ATTR_KILL_SGID  (1 << 12)
#define ATTR_FILE   (1 << 13)
#define ATTR_KILL_PRIV  (1 << 14)
#define ATTR_OPEN   (1 << 15) /* Truncating from open(O_TRUNC) */
#define ATTR_TIMES_SET  (1 << 16)

/*
 * 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 <[email protected]> 94-10-20
 */
struct iattr {
    unsigned int    ia_valid;
    umode_t     ia_mode;
    kuid_t      ia_uid;
    kgid_t      ia_gid;
    loff_t      ia_size;
    struct timespec ia_atime;
    struct timespec ia_mtime;
    struct timespec ia_ctime;

    /*
     * Not an attribute, but an auxiliary info for filesystems wanting to
     * implement an ftruncate() like method.  NOTE: filesystem should
     * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
     */
    struct file *ia_file;
};

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

enum positive_aop_returns {
    AOP_WRITEPAGE_ACTIVATE  = 0x80000,
    AOP_TRUNCATED_PAGE  = 0x80001,
};

#define AOP_FLAG_UNINTERRUPTIBLE    0x0001 /* will not do a short write */
#define AOP_FLAG_CONT_EXPAND        0x0002 /* called from cont_expand */
#define AOP_FLAG_NOFS           0x0004 /* used by filesystem to direct
                        * helper code (eg buffer layer)
                        * to clear GFP_FS from alloc */

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

struct iov_iter {
    const struct iovec *iov;
    unsigned long nr_segs;
    size_t iov_offset;
    size_t count;
};

size_t iov_iter_copy_from_user_atomic(struct page *page,
        struct iov_iter *i, unsigned long offset, size_t bytes);
size_t iov_iter_copy_from_user(struct page *page,
        struct iov_iter *i, unsigned long offset, size_t bytes);
void iov_iter_advance(struct iov_iter *i, size_t bytes);
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(struct iov_iter *i);

static inline void iov_iter_init(struct iov_iter *i,
            const struct iovec *iov, unsigned long nr_segs,
            size_t count, size_t written)
{
    i->iov = iov;
    i->nr_segs = nr_segs;
    i->iov_offset = 0;
    i->count = count + written;

    iov_iter_advance(i, written);
}

static inline size_t iov_iter_count(struct iov_iter *i)
{
    return i->count;
}

/*
 * "descriptor" for what we're up to with a read.
 * 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;
    union {
        char __user *buf;
        void *data;
    } arg;
    int error;
} read_descriptor_t;

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

struct address_space_operations {
    int (*writepage)(struct page *page, struct writeback_control *wbc);
    int (*readpage)(struct file *, struct page *);

    /* Write back some dirty pages from this mapping. */
    int (*writepages)(struct address_space *, struct writeback_control *);

    /* Set a page dirty.  Return true if this dirtied it */
    int (*set_page_dirty)(struct page *page);

    int (*readpages)(struct file *filp, struct address_space *mapping,
            struct list_head *pages, unsigned nr_pages);

    int (*write_begin)(struct file *, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata);
    int (*write_end)(struct file *, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned copied,
                struct page *page, void *fsdata);

    /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
    sector_t (*bmap)(struct address_space *, sector_t);
    void (*invalidatepage) (struct page *, unsigned long);
    int (*releasepage) (struct page *, gfp_t);
    void (*freepage)(struct page *);
    ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
            loff_t offset, unsigned long nr_segs);
    int (*get_xip_mem)(struct address_space *, pgoff_t, int,
                        void **, unsigned long *);
    /*
     * migrate the contents of a page to the specified target. If sync
     * is false, it must not block.
     */
    int (*migratepage) (struct address_space *,
            struct page *, struct page *, enum migrate_mode);
    int (*launder_page) (struct page *);
    int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
                    unsigned long);
    int (*error_remove_page)(struct address_space *, struct page *);

    /* swapfile support */
    int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
                sector_t *span);
    void (*swap_deactivate)(struct file *file);
};

extern const struct address_space_operations empty_aops;

/*
 * pagecache_write_begin/pagecache_write_end must be used by general code
 * to write into the pagecache.
 */
int pagecache_write_begin(struct file *, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata);

int pagecache_write_end(struct file *, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned copied,
                struct page *page, void *fsdata);

struct backing_dev_info;
struct address_space {
    struct inode        *host;      /* owner: inode, block_device */
    struct radix_tree_root  page_tree;  /* radix tree of all pages */
    spinlock_t      tree_lock;  /* and lock protecting it */
    unsigned int        i_mmap_writable;/* count VM_SHARED mappings */
    struct rb_root      i_mmap;     /* tree of private and shared mappings */
    struct list_head    i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
    struct mutex        i_mmap_mutex;   /* protect tree, count, list */
    /* Protected by tree_lock together with the radix tree */
    unsigned long       nrpages;    /* number of total pages */
    pgoff_t         writeback_index;/* writeback starts here */
    const struct address_space_operations *a_ops;   /* methods */
    unsigned long       flags;      /* error bits/gfp mask */
    struct backing_dev_info *backing_dev_info; /* device readahead, etc */
    spinlock_t      private_lock;   /* for use by the address_space */
    struct list_head    private_list;   /* ditto */
    struct address_space    *assoc_mapping; /* ditto */
} __attribute__((aligned(sizeof(long))));
    /*
     * On most architectures that alignment is already the case; but
     * must be enforced here for CRIS, to let the least significant bit
     * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
     */
struct request_queue;

struct block_device {
    dev_t           bd_dev;  /* not a kdev_t - it's a search key */
    int         bd_openers;
    struct inode *      bd_inode;   /* will die */
    struct super_block *    bd_super;
    struct mutex        bd_mutex;   /* open/close mutex */
    struct list_head    bd_inodes;
    void *          bd_claiming;
    void *          bd_holder;
    int         bd_holders;
    bool            bd_write_holder;
#ifdef CONFIG_SYSFS
    struct list_head    bd_holder_disks;
#endif
    struct block_device *   bd_contains;
    unsigned        bd_block_size;
    struct hd_struct *  bd_part;
    /* number of times partitions within this device have been opened. */
    unsigned        bd_part_count;
    int         bd_invalidated;
    struct gendisk *    bd_disk;
    struct request_queue *  bd_queue;
    struct list_head    bd_list;
    /*
     * Private data.  You must have bd_claim'ed the block_device
     * to use this.  NOTE:  bd_claim allows an owner to claim
     * the same device multiple times, the owner must take special
     * care to not mess up bd_private for that case.
     */
    unsigned long       bd_private;

    /* The counter of freeze processes */
    int         bd_fsfreeze_count;
    /* Mutex for freeze */
    struct mutex        bd_fsfreeze_mutex;
};

/*
 * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
 * radix trees
 */
#define PAGECACHE_TAG_DIRTY 0
#define PAGECACHE_TAG_WRITEBACK 1
#define PAGECACHE_TAG_TOWRITE   2

int mapping_tagged(struct address_space *mapping, int tag);

/*
 * Might pages of this file be mapped into userspace?
 */
static inline int mapping_mapped(struct address_space *mapping)
{
    return  !RB_EMPTY_ROOT(&mapping->i_mmap) ||
        !list_empty(&mapping->i_mmap_nonlinear);
}

/*
 * Might pages of this file have been modified in userspace?
 * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
 * marks vma as VM_SHARED if it is shared, and the file was opened for
 * writing i.e. vma may be mprotected writable even if now readonly.
 */
static inline int mapping_writably_mapped(struct address_space *mapping)
{
    return mapping->i_mmap_writable != 0;
}

/*
 * Use sequence counter to get consistent i_size on 32-bit processors.
 */
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
#include <linux/seqlock.h>
#define __NEED_I_SIZE_ORDERED
#define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
#else
#define i_size_ordered_init(inode) do { } while (0)
#endif

struct posix_acl;
#define ACL_NOT_CACHED ((void *)(-1))

#define IOP_FASTPERM    0x0001
#define IOP_LOOKUP  0x0002
#define IOP_NOFOLLOW    0x0004

/*
 * Keep mostly read-only and often accessed (especially for
 * the RCU path lookup and 'stat' data) fields at the beginning
 * of the 'struct inode'
 */
struct inode {
    umode_t         i_mode;
    unsigned short      i_opflags;
    kuid_t          i_uid;
    kgid_t          i_gid;
    unsigned int        i_flags;

#ifdef CONFIG_FS_POSIX_ACL
    struct posix_acl    *i_acl;
    struct posix_acl    *i_default_acl;
#endif

    const struct inode_operations   *i_op;
    struct super_block  *i_sb;
    struct address_space    *i_mapping;

#ifdef CONFIG_SECURITY
    void            *i_security;
#endif

    /* Stat data, not accessed from path walking */
    unsigned long       i_ino;
    /*
     * Filesystems may only read i_nlink directly.  They shall use the
     * following functions for modification:
     *
     *    (set|clear|inc|drop)_nlink
     *    inode_(inc|dec)_link_count
     */
    union {
        const unsigned int i_nlink;
        unsigned int __i_nlink;
    };
    dev_t           i_rdev;
    loff_t          i_size;
    struct timespec     i_atime;
    struct timespec     i_mtime;
    struct timespec     i_ctime;
    spinlock_t      i_lock; /* i_blocks, i_bytes, maybe i_size */
    unsigned short          i_bytes;
    unsigned int        i_blkbits;
    blkcnt_t        i_blocks;

#ifdef __NEED_I_SIZE_ORDERED
    seqcount_t      i_size_seqcount;
#endif

    /* Misc */
    unsigned long       i_state;
    struct mutex        i_mutex;

    unsigned long       dirtied_when;   /* jiffies of first dirtying */

    struct hlist_node   i_hash;
    struct list_head    i_wb_list;  /* backing dev IO list */
    struct list_head    i_lru;      /* inode LRU list */
    struct list_head    i_sb_list;
    union {
        struct hlist_head   i_dentry;
        struct rcu_head     i_rcu;
    };
    u64         i_version;
    atomic_t        i_count;
    atomic_t        i_dio_count;
    atomic_t        i_writecount;
    const struct file_operations    *i_fop; /* former ->i_op->default_file_ops */
    struct file_lock    *i_flock;
    struct address_space    i_data;
#ifdef CONFIG_QUOTA
    struct dquot        *i_dquot[MAXQUOTAS];
#endif
    struct list_head    i_devices;
    union {
        struct pipe_inode_info  *i_pipe;
        struct block_device *i_bdev;
        struct cdev     *i_cdev;
    };

    __u32           i_generation;

#ifdef CONFIG_FSNOTIFY
    __u32           i_fsnotify_mask; /* all events this inode cares about */
    struct hlist_head   i_fsnotify_marks;
#endif

#ifdef CONFIG_IMA
    atomic_t        i_readcount; /* struct files open RO */
#endif
    void            *i_private; /* fs or device private pointer */
};

static inline int inode_unhashed(struct inode *inode)
{
    return hlist_unhashed(&inode->i_hash);
}

/*
 * inode->i_mutex nesting subclasses for the lock validator:
 *
 * 0: the object of the current VFS operation
 * 1: parent
 * 2: child/target
 * 3: quota file
 *
 * The locking order between these classes is
 * parent -> child -> normal -> xattr -> quota
 */
enum inode_i_mutex_lock_class
{
    I_MUTEX_NORMAL,
    I_MUTEX_PARENT,
    I_MUTEX_CHILD,
    I_MUTEX_XATTR,
    I_MUTEX_QUOTA
};

/*
 * NOTE: in a 32bit arch with a preemptable kernel and
 * an UP compile the i_size_read/write must be atomic
 * with respect to the local cpu (unlike with preempt disabled),
 * but they don't need to be atomic with respect to other cpus like in
 * true SMP (so they need either to either locally disable irq around
 * the read or for example on x86 they can be still implemented as a
 * cmpxchg8b without the need of the lock prefix). For SMP compiles
 * and 64bit archs it makes no difference if preempt is enabled or not.
 */
static inline loff_t i_size_read(const struct inode *inode)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
    loff_t i_size;
    unsigned int seq;

    do {
        seq = read_seqcount_begin(&inode->i_size_seqcount);
        i_size = inode->i_size;
    } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
    return i_size;
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
    loff_t i_size;

    preempt_disable();
    i_size = inode->i_size;
    preempt_enable();
    return i_size;
#else
    return inode->i_size;
#endif
}

/*
 * NOTE: unlike i_size_read(), i_size_write() does need locking around it
 * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
 * can be lost, resulting in subsequent i_size_read() calls spinning forever.
 */
static inline void i_size_write(struct inode *inode, loff_t i_size)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
    write_seqcount_begin(&inode->i_size_seqcount);
    inode->i_size = i_size;
    write_seqcount_end(&inode->i_size_seqcount);
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
    preempt_disable();
    inode->i_size = i_size;
    preempt_enable();
#else
    inode->i_size = i_size;
#endif
}

/* Helper functions so that in most cases filesystems will
 * not need to deal directly with kuid_t and kgid_t and can
 * instead deal with the raw numeric values that are stored
 * in the filesystem.
 */
static inline uid_t i_uid_read(const struct inode *inode)
{
    return from_kuid(&init_user_ns, inode->i_uid);
}

static inline gid_t i_gid_read(const struct inode *inode)
{
    return from_kgid(&init_user_ns, inode->i_gid);
}

static inline void i_uid_write(struct inode *inode, uid_t uid)
{
    inode->i_uid = make_kuid(&init_user_ns, uid);
}

static inline void i_gid_write(struct inode *inode, gid_t gid)
{
    inode->i_gid = make_kgid(&init_user_ns, gid);
}

static inline unsigned iminor(const struct inode *inode)
{
    return MINOR(inode->i_rdev);
}

static inline unsigned imajor(const struct inode *inode)
{
    return MAJOR(inode->i_rdev);
}

extern struct block_device *I_BDEV(struct inode *inode);

struct fown_struct {
    rwlock_t lock;          /* protects pid, uid, euid fields */
    struct pid *pid;    /* pid or -pgrp where SIGIO should be sent */
    enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
    kuid_t uid, euid;   /* uid/euid of process setting the owner */
    int signum;     /* posix.1b rt signal to be delivered on IO */
};

/*
 * Track a single file's readahead state
 */
struct file_ra_state {
    pgoff_t start;          /* where readahead started */
    unsigned int size;      /* # of readahead pages */
    unsigned int async_size;    /* do asynchronous readahead when
                       there are only # of pages ahead */

    unsigned int ra_pages;      /* Maximum readahead window */
    unsigned int mmap_miss;     /* Cache miss stat for mmap accesses */
    loff_t prev_pos;        /* Cache last read() position */
};

/*
 * Check if @index falls in the readahead windows.
 */
static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
{
    return (index >= ra->start &&
        index <  ra->start + ra->size);
}

#define FILE_MNT_WRITE_TAKEN    1
#define FILE_MNT_WRITE_RELEASED 2

struct file {
    /*
     * fu_list becomes invalid after file_free is called and queued via
     * fu_rcuhead for RCU freeing
     */
    union {
        struct list_head    fu_list;
        struct rcu_head     fu_rcuhead;
    } f_u;
    struct path     f_path;
#define f_dentry    f_path.dentry
#define f_vfsmnt    f_path.mnt
    const struct file_operations    *f_op;

    /*
     * Protects f_ep_links, f_flags, f_pos vs i_size in lseek SEEK_CUR.
     * Must not be taken from IRQ context.
     */
    spinlock_t      f_lock;
#ifdef CONFIG_SMP
    int         f_sb_list_cpu;
#endif
    atomic_long_t       f_count;
    unsigned int        f_flags;
    fmode_t         f_mode;
    loff_t          f_pos;
    struct fown_struct  f_owner;
    const struct cred   *f_cred;
    struct file_ra_state    f_ra;

    u64         f_version;
#ifdef CONFIG_SECURITY
    void            *f_security;
#endif
    /* needed for tty driver, and maybe others */
    void            *private_data;

#ifdef CONFIG_EPOLL
    /* Used by fs/eventpoll.c to link all the hooks to this file */
    struct list_head    f_ep_links;
    struct list_head    f_tfile_llink;
#endif /* #ifdef CONFIG_EPOLL */
    struct address_space    *f_mapping;
#ifdef CONFIG_DEBUG_WRITECOUNT
    unsigned long f_mnt_write_state;
#endif
};

struct file_handle {
    __u32 handle_bytes;
    int handle_type;
    /* file identifier */
    unsigned char f_handle[0];
};

static inline struct file *get_file(struct file *f)
{
    atomic_long_inc(&f->f_count);
    return f;
}
#define fput_atomic(x)  atomic_long_add_unless(&(x)->f_count, -1, 1)
#define file_count(x)   atomic_long_read(&(x)->f_count)

#ifdef CONFIG_DEBUG_WRITECOUNT
static inline void file_take_write(struct file *f)
{
    WARN_ON(f->f_mnt_write_state != 0);
    f->f_mnt_write_state = FILE_MNT_WRITE_TAKEN;
}
static inline void file_release_write(struct file *f)
{
    f->f_mnt_write_state |= FILE_MNT_WRITE_RELEASED;
}
static inline void file_reset_write(struct file *f)
{
    f->f_mnt_write_state = 0;
}
static inline void file_check_state(struct file *f)
{
    /*
     * At this point, either both or neither of these bits
     * should be set.
     */
    WARN_ON(f->f_mnt_write_state == FILE_MNT_WRITE_TAKEN);
    WARN_ON(f->f_mnt_write_state == FILE_MNT_WRITE_RELEASED);
}
static inline int file_check_writeable(struct file *f)
{
    if (f->f_mnt_write_state == FILE_MNT_WRITE_TAKEN)
        return 0;
    printk(KERN_WARNING "writeable file with no "
                "mnt_want_write()\n");
    WARN_ON(1);
    return -EINVAL;
}
#else /* !CONFIG_DEBUG_WRITECOUNT */
static inline void file_take_write(struct file *filp) {}
static inline void file_release_write(struct file *filp) {}
static inline void file_reset_write(struct file *filp) {}
static inline void file_check_state(struct file *filp) {}
static inline int file_check_writeable(struct file *filp)
{
    return 0;
}
#endif /* CONFIG_DEBUG_WRITECOUNT */

#define MAX_NON_LFS ((1UL<<31) - 1)

/* Page cache limit. The filesystems should put that into their s_maxbytes 
   limits, otherwise bad things can happen in VM. */ 
#if BITS_PER_LONG==32
#define MAX_LFS_FILESIZE    (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1) 
#elif BITS_PER_LONG==64
#define MAX_LFS_FILESIZE    ((loff_t)0x7fffffffffffffffLL)
#endif

#define FL_POSIX    1
#define FL_FLOCK    2
#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 */

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

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

struct lock_manager_operations {
    int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
    void (*lm_notify)(struct file_lock *);  /* unblock callback */
    int (*lm_grant)(struct file_lock *, struct file_lock *, int);
    void (*lm_break)(struct file_lock *);
    int (*lm_change)(struct file_lock **, int);
};

struct lock_manager {
    struct list_head list;
};

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

/* that will die - we need it for nfs_lock_info */
#include <linux/nfs_fs_i.h>

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_flags;
    unsigned char fl_type;
    unsigned int fl_pid;
    struct pid *fl_nspid;
    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 */
        } afs;
    } 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)
#define OFFT_OFFSET_MAX INT_LIMIT(off_t)
#endif

#include <linux/fcntl.h>

extern void send_sigio(struct fown_struct *fown, int fd, int band);

#ifdef CONFIG_FILE_LOCKING
extern int fcntl_getlk(struct file *, struct flock __user *);
extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
            struct flock __user *);

#if BITS_PER_LONG == 32
extern int fcntl_getlk64(struct file *, struct flock64 __user *);
extern int fcntl_setlk64(unsigned int, struct file *, unsigned int,
            struct flock64 __user *);
#endif

extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
extern int fcntl_getlease(struct file *filp);

/* fs/locks.c */
void locks_free_lock(struct file_lock *fl);
extern void locks_init_lock(struct file_lock *);
extern struct file_lock * locks_alloc_lock(void);
extern void locks_copy_lock(struct file_lock *, struct file_lock *);
extern void __locks_copy_lock(struct file_lock *, const struct file_lock *);
extern void locks_remove_posix(struct file *, fl_owner_t);
extern void locks_remove_flock(struct file *);
extern void locks_release_private(struct file_lock *);
extern void posix_test_lock(struct file *, struct file_lock *);
extern int posix_lock_file(struct file *, struct file_lock *, struct file_lock *);
extern int posix_lock_file_wait(struct file *, struct file_lock *);
extern int posix_unblock_lock(struct file *, struct file_lock *);
extern int vfs_test_lock(struct file *, struct file_lock *);
extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
extern int __break_lease(struct inode *inode, unsigned int flags);
extern void lease_get_mtime(struct inode *, struct timespec *time);
extern int generic_setlease(struct file *, long, struct file_lock **);
extern int vfs_setlease(struct file *, long, struct file_lock **);
extern int lease_modify(struct file_lock **, int);
extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
extern void locks_delete_block(struct file_lock *waiter);
extern void lock_flocks(void);
extern void unlock_flocks(void);
#else /* !CONFIG_FILE_LOCKING */
static inline int fcntl_getlk(struct file *file, struct flock __user *user)
{
    return -EINVAL;
}

static inline int fcntl_setlk(unsigned int fd, struct file *file,
                  unsigned int cmd, struct flock __user *user)
{
    return -EACCES;
}

#if BITS_PER_LONG == 32
static inline int fcntl_getlk64(struct file *file, struct flock64 __user *user)
{
    return -EINVAL;
}

static inline int fcntl_setlk64(unsigned int fd, struct file *file,
                unsigned int cmd, struct flock64 __user *user)
{
    return -EACCES;
}
#endif
static inline int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
{
    return 0;
}

static inline int fcntl_getlease(struct file *filp)
{
    return 0;
}

static inline void locks_init_lock(struct file_lock *fl)
{
    return;
}

static inline void __locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
    return;
}

static inline void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
    return;
}

static inline void locks_remove_posix(struct file *filp, fl_owner_t owner)
{
    return;
}

static inline void locks_remove_flock(struct file *filp)
{
    return;
}

static inline void posix_test_lock(struct file *filp, struct file_lock *fl)
{
    return;
}

static inline int posix_lock_file(struct file *filp, struct file_lock *fl,
                  struct file_lock *conflock)
{
    return -ENOLCK;
}

static inline int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
{
    return -ENOLCK;
}

static inline int posix_unblock_lock(struct file *filp,
                     struct file_lock *waiter)
{
    return -ENOENT;
}

static inline int vfs_test_lock(struct file *filp, struct file_lock *fl)
{
    return 0;
}

static inline int vfs_lock_file(struct file *filp, unsigned int cmd,
                struct file_lock *fl, struct file_lock *conf)
{
    return -ENOLCK;
}

static inline int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
{
    return 0;
}

static inline int flock_lock_file_wait(struct file *filp,
                       struct file_lock *request)
{
    return -ENOLCK;
}

static inline int __break_lease(struct inode *inode, unsigned int mode)
{
    return 0;
}

static inline void lease_get_mtime(struct inode *inode, struct timespec *time)
{
    return;
}

static inline int generic_setlease(struct file *filp, long arg,
                    struct file_lock **flp)
{
    return -EINVAL;
}

static inline int vfs_setlease(struct file *filp, long arg,
                   struct file_lock **lease)
{
    return -EINVAL;
}

static inline int lease_modify(struct file_lock **before, int arg)
{
    return -EINVAL;
}

static inline int lock_may_read(struct inode *inode, loff_t start,
                unsigned long len)
{
    return 1;
}

static inline int lock_may_write(struct inode *inode, loff_t start,
                 unsigned long len)
{
    return 1;
}

static inline void locks_delete_block(struct file_lock *waiter)
{
}

static inline void lock_flocks(void)
{
}

static inline void unlock_flocks(void)
{
}

#endif /* !CONFIG_FILE_LOCKING */


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

#define FASYNC_MAGIC 0x4601

/* SMP safe fasync helpers: */
extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
extern struct fasync_struct *fasync_insert_entry(int, struct file *, struct fasync_struct **, struct fasync_struct *);
extern int fasync_remove_entry(struct file *, struct fasync_struct **);
extern struct fasync_struct *fasync_alloc(void);
extern void fasync_free(struct fasync_struct *);

/* can be called from interrupts */
extern void kill_fasync(struct fasync_struct **, int, int);

extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
extern int f_setown(struct file *filp, unsigned long arg, int force);
extern void f_delown(struct file *filp);
extern pid_t f_getown(struct file *filp);
extern int send_sigurg(struct fown_struct *fown);

struct mm_struct;

/*
 *  Umount options
 */

#define MNT_FORCE   0x00000001  /* Attempt to forcibily umount */
#define MNT_DETACH  0x00000002  /* Just detach from the tree */
#define MNT_EXPIRE  0x00000004  /* Mark for expiry */
#define UMOUNT_NOFOLLOW 0x00000008  /* Don't follow symlink on umount */
#define UMOUNT_UNUSED   0x80000000  /* Flag guaranteed to be unused */

extern struct list_head super_blocks;
extern spinlock_t sb_lock;

/* Possible states of 'frozen' field */
enum {
    SB_UNFROZEN = 0,        /* FS is unfrozen */
    SB_FREEZE_WRITE = 1,        /* Writes, dir ops, ioctls frozen */
    SB_FREEZE_PAGEFAULT = 2,    /* Page faults stopped as well */
    SB_FREEZE_FS = 3,       /* For internal FS use (e.g. to stop
                     * internal threads if needed) */
    SB_FREEZE_COMPLETE = 4,     /* ->freeze_fs finished successfully */
};

#define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)

struct sb_writers {
    /* Counters for counting writers at each level */
    struct percpu_counter   counter[SB_FREEZE_LEVELS];
    wait_queue_head_t   wait;       /* queue for waiting for
                           writers / faults to finish */
    int         frozen;     /* Is sb frozen? */
    wait_queue_head_t   wait_unfrozen;  /* queue for waiting for
                           sb to be thawed */
#ifdef CONFIG_DEBUG_LOCK_ALLOC
    struct lockdep_map  lock_map[SB_FREEZE_LEVELS];
#endif
};

struct super_block {
    struct list_head    s_list;     /* Keep this first */
    dev_t           s_dev;      /* search index; _not_ kdev_t */
    unsigned char       s_blocksize_bits;
    unsigned long       s_blocksize;
    loff_t          s_maxbytes; /* Max file size */
    struct file_system_type *s_type;
    const struct super_operations   *s_op;
    const struct dquot_operations   *dq_op;
    const struct quotactl_ops   *s_qcop;
    const struct export_operations *s_export_op;
    unsigned long       s_flags;
    unsigned long       s_magic;
    struct dentry       *s_root;
    struct rw_semaphore s_umount;
    int         s_count;
    atomic_t        s_active;
#ifdef CONFIG_SECURITY
    void                    *s_security;
#endif
    const struct xattr_handler **s_xattr;

    struct list_head    s_inodes;   /* all inodes */
    struct hlist_bl_head    s_anon;     /* anonymous dentries for (nfs) exporting */
#ifdef CONFIG_SMP
    struct list_head __percpu *s_files;
#else
    struct list_head    s_files;
#endif
    struct list_head    s_mounts;   /* list of mounts; _not_ for fs use */
    /* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
    struct list_head    s_dentry_lru;   /* unused dentry lru */
    int         s_nr_dentry_unused; /* # of dentry on lru */

    /* s_inode_lru_lock protects s_inode_lru and s_nr_inodes_unused */
    spinlock_t      s_inode_lru_lock ____cacheline_aligned_in_smp;
    struct list_head    s_inode_lru;        /* unused inode lru */
    int         s_nr_inodes_unused; /* # of inodes on lru */

    struct block_device *s_bdev;
    struct backing_dev_info *s_bdi;
    struct mtd_info     *s_mtd;
    struct hlist_node   s_instances;
    struct quota_info   s_dquot;    /* Diskquota specific options */

    struct sb_writers   s_writers;

    char s_id[32];              /* Informational name */
    u8 s_uuid[16];              /* UUID */

    void            *s_fs_info; /* Filesystem private info */
    unsigned int        s_max_links;
    fmode_t         s_mode;

    /* Granularity of c/m/atime in ns.
       Cannot be worse than a second */
    u32        s_time_gran;

    /*
     * The next field is for VFS *only*. No filesystems have any business
     * even looking at it. You had been warned.
     */
    struct mutex s_vfs_rename_mutex;    /* Kludge */

    /*
     * Filesystem subtype.  If non-empty the filesystem type field
     * in /proc/mounts will be "type.subtype"
     */
    char *s_subtype;

    /*
     * Saved mount options for lazy filesystems using
     * generic_show_options()
     */
    char __rcu *s_options;
    const struct dentry_operations *s_d_op; /* default d_op for dentries */

    /*
     * Saved pool identifier for cleancache (-1 means none)
     */
    int cleancache_poolid;

    struct shrinker s_shrink;   /* per-sb shrinker handle */

    /* Number of inodes with nlink == 0 but still referenced */
    atomic_long_t s_remove_count;

    /* Being remounted read-only */
    int s_readonly_remount;
};

/* superblock cache pruning functions */
extern void prune_icache_sb(struct super_block *sb, int nr_to_scan);
extern void prune_dcache_sb(struct super_block *sb, int nr_to_scan);

extern struct timespec current_fs_time(struct super_block *sb);

/*
 * Snapshotting support.
 */

void __sb_end_write(struct super_block *sb, int level);
int __sb_start_write(struct super_block *sb, int level, bool wait);

static inline void sb_end_write(struct super_block *sb)
{
    __sb_end_write(sb, SB_FREEZE_WRITE);
}

static inline void sb_end_pagefault(struct super_block *sb)
{
    __sb_end_write(sb, SB_FREEZE_PAGEFAULT);
}

static inline void sb_end_intwrite(struct super_block *sb)
{
    __sb_end_write(sb, SB_FREEZE_FS);
}

static inline void sb_start_write(struct super_block *sb)
{
    __sb_start_write(sb, SB_FREEZE_WRITE, true);
}

static inline int sb_start_write_trylock(struct super_block *sb)
{
    return __sb_start_write(sb, SB_FREEZE_WRITE, false);
}

static inline void sb_start_pagefault(struct super_block *sb)
{
    __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
}

/*
 * sb_start_intwrite - get write access to a superblock for internal fs purposes
 * @sb: the super we write to
 *
 * This is the third level of protection against filesystem freezing. It is
 * free for use by a filesystem. The only requirement is that it must rank
 * below sb_start_pagefault.
 *
 * For example filesystem can call sb_start_intwrite() when starting a
 * transaction which somewhat eases handling of freezing for internal sources
 * of filesystem changes (internal fs threads, discarding preallocation on file
 * close, etc.).
 */
static inline void sb_start_intwrite(struct super_block *sb)
{
    __sb_start_write(sb, SB_FREEZE_FS, true);
}


extern bool inode_owner_or_capable(const struct inode *inode);

/* not quite ready to be deprecated, but... */
extern void lock_super(struct super_block *);
extern void unlock_super(struct super_block *);

/*
 * VFS helper functions..
 */
extern int vfs_create(struct inode *, struct dentry *, umode_t, bool);
extern int vfs_mkdir(struct inode *, struct dentry *, umode_t);
extern int vfs_mknod(struct inode *, struct dentry *, umode_t, 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 *);

/*
 * VFS dentry helper functions.
 */
extern void dentry_unhash(struct dentry *dentry);

/*
 * VFS file helper functions.
 */
extern void inode_init_owner(struct inode *inode, const struct inode *dir,
            umode_t mode);
/*
 * VFS FS_IOC_FIEMAP helper definitions.
 */
struct fiemap_extent_info {
    unsigned int fi_flags;      /* Flags as passed from user */
    unsigned int fi_extents_mapped; /* Number of mapped extents */
    unsigned int fi_extents_max;    /* Size of fiemap_extent array */
    struct fiemap_extent __user *fi_extents_start; /* Start of
                            fiemap_extent array */
};
int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
                u64 phys, u64 len, u32 flags);
int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);

/*
 * File types
 *
 * NOTE! These match bits 12..15 of stat.st_mode
 * (ie "(i_mode >> 12) & 15").
 */
#define DT_UNKNOWN  0
#define DT_FIFO     1
#define DT_CHR      2
#define DT_DIR      4
#define DT_BLK      6
#define DT_REG      8
#define DT_LNK      10
#define DT_SOCK     12
#define DT_WHT      14

/*
 * 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, loff_t, u64, unsigned);
struct block_device_operations;

/* These macros are for out of kernel modules to test that
 * the kernel supports the unlocked_ioctl and compat_ioctl
 * fields in struct file_operations. */
#define HAVE_COMPAT_IOCTL 1
#define HAVE_UNLOCKED_IOCTL 1

struct file_operations {
    struct module *owner;
    loff_t (*llseek) (struct file *, loff_t, int);
    ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
    ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
    ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
    ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
    int (*readdir) (struct file *, void *, filldir_t);
    unsigned int (*poll) (struct file *, struct poll_table_struct *);
    long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
    long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
    int (*mmap) (struct file *, struct vm_area_struct *);
    int (*open) (struct inode *, struct file *);
    int (*flush) (struct file *, fl_owner_t id);
    int (*release) (struct inode *, struct file *);
    int (*fsync) (struct file *, loff_t, loff_t, int datasync);
    int (*aio_fsync) (struct kiocb *, int datasync);
    int (*fasync) (int, struct file *, int);
    int (*lock) (struct file *, int, struct file_lock *);
    ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
    unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
    int (*check_flags)(int);
    int (*flock) (struct file *, int, struct file_lock *);
    ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
    ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
    int (*setlease)(struct file *, long, struct file_lock **);
    long (*fallocate)(struct file *file, int mode, loff_t offset,
              loff_t len);
};

struct inode_operations {
    struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
    void * (*follow_link) (struct dentry *, struct nameidata *);
    int (*permission) (struct inode *, int);
    struct posix_acl * (*get_acl)(struct inode *, int);

    int (*readlink) (struct dentry *, char __user *,int);
    void (*put_link) (struct dentry *, struct nameidata *, void *);

    int (*create) (struct inode *,struct dentry *, umode_t, bool);
    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 *,umode_t);
    int (*rmdir) (struct inode *,struct dentry *);
    int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
    int (*rename) (struct inode *, struct dentry *,
            struct inode *, struct dentry *);
    void (*truncate) (struct inode *);
    int (*setattr) (struct dentry *, struct iattr *);
    int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
    int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
    ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
    ssize_t (*listxattr) (struct dentry *, char *, size_t);
    int (*removexattr) (struct dentry *, const char *);
    int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
              u64 len);
    int (*update_time)(struct inode *, struct timespec *, int);
    int (*atomic_open)(struct inode *, struct dentry *,
               struct file *, unsigned open_flag,
               umode_t create_mode, int *opened);
} ____cacheline_aligned;

struct seq_file;

ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
                  unsigned long nr_segs, unsigned long fast_segs,
                  struct iovec *fast_pointer,
                  struct iovec **ret_pointer);

extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
        unsigned long, loff_t *);
extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
        unsigned long, loff_t *);

struct super_operations {
    struct inode *(*alloc_inode)(struct super_block *sb);
    void (*destroy_inode)(struct inode *);

    void (*dirty_inode) (struct inode *, int flags);
    int (*write_inode) (struct inode *, struct writeback_control *wbc);
    int (*drop_inode) (struct inode *);
    void (*evict_inode) (struct inode *);
    void (*put_super) (struct super_block *);
    int (*sync_fs)(struct super_block *sb, int wait);
    int (*freeze_fs) (struct super_block *);
    int (*unfreeze_fs) (struct super_block *);
    int (*statfs) (struct dentry *, struct kstatfs *);
    int (*remount_fs) (struct super_block *, int *, char *);
    void (*umount_begin) (struct super_block *);

    int (*show_options)(struct seq_file *, struct dentry *);
    int (*show_devname)(struct seq_file *, struct dentry *);
    int (*show_path)(struct seq_file *, struct dentry *);
    int (*show_stats)(struct seq_file *, struct dentry *);
#ifdef CONFIG_QUOTA
    ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
    ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
#endif
    int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
    int (*nr_cached_objects)(struct super_block *);
    void (*free_cached_objects)(struct super_block *, int);
};

/*
 * Inode flags - they have no relation to superblock flags now
 */
#define S_SYNC      1   /* Writes are synced at once */
#define S_NOATIME   2   /* Do not update access times */
#define S_APPEND    4   /* Append-only file */
#define S_IMMUTABLE 8   /* Immutable file */
#define S_DEAD      16  /* removed, but still open directory */
#define S_NOQUOTA   32  /* Inode is not counted to quota */
#define S_DIRSYNC   64  /* Directory modifications are synchronous */
#define S_NOCMTIME  128 /* Do not update file c/mtime */
#define S_SWAPFILE  256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE   512 /* Inode is fs-internal */
#define S_IMA       1024    /* Inode has an associated IMA struct */
#define S_AUTOMOUNT 2048    /* Automount/referral quasi-directory */
#define S_NOSEC     4096    /* no suid or xattr security attributes */

/*
 * 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. -- [email protected]
 */
#define __IS_FLG(inode, flg)    ((inode)->i_sb->s_flags & (flg))

#define IS_RDONLY(inode)    ((inode)->i_sb->s_flags & MS_RDONLY)
#define IS_SYNC(inode)      (__IS_FLG(inode, MS_SYNCHRONOUS) || \
                    ((inode)->i_flags & S_SYNC))
#define IS_DIRSYNC(inode)   (__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
                    ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
#define IS_MANDLOCK(inode)  __IS_FLG(inode, MS_MANDLOCK)
#define IS_NOATIME(inode)   __IS_FLG(inode, MS_RDONLY|MS_NOATIME)
#define IS_I_VERSION(inode) __IS_FLG(inode, MS_I_VERSION)

#define IS_NOQUOTA(inode)   ((inode)->i_flags & S_NOQUOTA)
#define IS_APPEND(inode)    ((inode)->i_flags & S_APPEND)
#define IS_IMMUTABLE(inode) ((inode)->i_flags & S_IMMUTABLE)
#define IS_POSIXACL(inode)  __IS_FLG(inode, MS_POSIXACL)

#define IS_DEADDIR(inode)   ((inode)->i_flags & S_DEAD)
#define IS_NOCMTIME(inode)  ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode)  ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode)   ((inode)->i_flags & S_PRIVATE)
#define IS_IMA(inode)       ((inode)->i_flags & S_IMA)
#define IS_AUTOMOUNT(inode) ((inode)->i_flags & S_AUTOMOUNT)
#define IS_NOSEC(inode)     ((inode)->i_flags & S_NOSEC)

/*
 * Inode state bits.  Protected by inode->i_lock
 *
 * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
 * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
 *
 * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
 * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
 * various stages of removing an inode.
 *
 * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
 *
 * I_DIRTY_SYNC     Inode is dirty, but doesn't have to be written on
 *          fdatasync().  i_atime is the usual cause.
 * I_DIRTY_DATASYNC Data-related inode changes pending. We keep track of
 *          these changes separately from I_DIRTY_SYNC so that we
 *          don't have to write inode on fdatasync() when only
 *          mtime has changed in it.
 * I_DIRTY_PAGES    Inode has dirty pages.  Inode itself may be clean.
 * I_NEW        Serves as both a mutex and completion notification.
 *          New inodes set I_NEW.  If two processes both create
 *          the same inode, one of them will release its inode and
 *          wait for I_NEW to be released before returning.
 *          Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
 *          also cause waiting on I_NEW, without I_NEW actually
 *          being set.  find_inode() uses this to prevent returning
 *          nearly-dead inodes.
 * I_WILL_FREE      Must be set when calling write_inode_now() if i_count
 *          is zero.  I_FREEING must be set when I_WILL_FREE is
 *          cleared.
 * I_FREEING        Set when inode is about to be freed but still has dirty
 *          pages or buffers attached or the inode itself is still
 *          dirty.
 * I_CLEAR      Added by clear_inode().  In this state the inode is
 *          clean and can be destroyed.  Inode keeps I_FREEING.
 *
 *          Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
 *          prohibited for many purposes.  iget() must wait for
 *          the inode to be completely released, then create it
 *          anew.  Other functions will just ignore such inodes,
 *          if appropriate.  I_NEW is used for waiting.
 *
 * I_SYNC       Writeback of inode is running. The bit is set during
 *          data writeback, and cleared with a wakeup on the bit
 *          address once it is done. The bit is also used to pin
 *          the inode in memory for flusher thread.
 *
 * I_REFERENCED     Marks the inode as recently references on the LRU list.
 *
 * I_DIO_WAKEUP     Never set.  Only used as a key for wait_on_bit().
 *
 * Q: What is the difference between I_WILL_FREE and I_FREEING?
 */
#define I_DIRTY_SYNC        (1 << 0)
#define I_DIRTY_DATASYNC    (1 << 1)
#define I_DIRTY_PAGES       (1 << 2)
#define __I_NEW         3
#define I_NEW           (1 << __I_NEW)
#define I_WILL_FREE     (1 << 4)
#define I_FREEING       (1 << 5)
#define I_CLEAR         (1 << 6)
#define __I_SYNC        7
#define I_SYNC          (1 << __I_SYNC)
#define I_REFERENCED        (1 << 8)
#define __I_DIO_WAKEUP      9
#define I_DIO_WAKEUP        (1 << I_DIO_WAKEUP)

#define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)

extern void __mark_inode_dirty(struct inode *, int);
static inline void mark_inode_dirty(struct inode *inode)
{
    __mark_inode_dirty(inode, I_DIRTY);
}

static inline void mark_inode_dirty_sync(struct inode *inode)
{
    __mark_inode_dirty(inode, I_DIRTY_SYNC);
}

extern void inc_nlink(struct inode *inode);
extern void drop_nlink(struct inode *inode);
extern void clear_nlink(struct inode *inode);
extern void set_nlink(struct inode *inode, unsigned int nlink);

static inline void inode_inc_link_count(struct inode *inode)
{
    inc_nlink(inode);
    mark_inode_dirty(inode);
}

static inline void inode_dec_link_count(struct inode *inode)
{
    drop_nlink(inode);
    mark_inode_dirty(inode);
}

static inline void inode_inc_iversion(struct inode *inode)
{
       spin_lock(&inode->i_lock);
       inode->i_version++;
       spin_unlock(&inode->i_lock);
}

enum file_time_flags {
    S_ATIME = 1,
    S_MTIME = 2,
    S_CTIME = 4,
    S_VERSION = 8,
};

extern void touch_atime(struct path *);
static inline void file_accessed(struct file *file)
{
    if (!(file->f_flags & O_NOATIME))
        touch_atime(&file->f_path);
}

int sync_inode(struct inode *inode, struct writeback_control *wbc);
int sync_inode_metadata(struct inode *inode, int wait);

struct file_system_type {
    const char *name;
    int fs_flags;
#define FS_REQUIRES_DEV     1 
#define FS_BINARY_MOUNTDATA 2
#define FS_HAS_SUBTYPE      4
#define FS_REVAL_DOT        16384   /* Check the paths ".", ".." for staleness */
#define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
    struct dentry *(*mount) (struct file_system_type *, int,
               const char *, void *);
    void (*kill_sb) (struct super_block *);
    struct module *owner;
    struct file_system_type * next;
    struct hlist_head fs_supers;

    struct lock_class_key s_lock_key;
    struct lock_class_key s_umount_key;
    struct lock_class_key s_vfs_rename_key;
    struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];

    struct lock_class_key i_lock_key;
    struct lock_class_key i_mutex_key;
    struct lock_class_key i_mutex_dir_key;
};

extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
    void *data, int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_bdev(struct file_system_type *fs_type,
    int flags, const char *dev_name, void *data,
    int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_single(struct file_system_type *fs_type,
    int flags, void *data,
    int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_nodev(struct file_system_type *fs_type,
    int flags, void *data,
    int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
void generic_shutdown_super(struct super_block *sb);
void kill_block_super(struct super_block *sb);
void kill_anon_super(struct super_block *sb);
void kill_litter_super(struct super_block *sb);
void deactivate_super(struct super_block *sb);
void deactivate_locked_super(struct super_block *sb);
int set_anon_super(struct super_block *s, void *data);
int get_anon_bdev(dev_t *);
void free_anon_bdev(dev_t);
struct super_block *sget(struct file_system_type *type,
            int (*test)(struct super_block *,void *),
            int (*set)(struct super_block *,void *),
            int flags, void *data);
extern struct dentry *mount_pseudo(struct file_system_type *, char *,
    const struct super_operations *ops,
    const struct dentry_operations *dops,
    unsigned long);

/* Alas, no aliases. Too much hassle with bringing module.h everywhere */
#define fops_get(fops) \
    (((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
#define fops_put(fops) \
    do { if (fops) module_put((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_data(struct file_system_type *, void *data);
#define kern_mount(type) kern_mount_data(type, NULL)
extern void kern_unmount(struct vfsmount *mnt);
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
extern long do_mount(const char *, const char *, const char *, unsigned long, void *);
extern struct vfsmount *collect_mounts(struct path *);
extern void drop_collected_mounts(struct vfsmount *);
extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
              struct vfsmount *);
extern int vfs_statfs(struct path *, struct kstatfs *);
extern int user_statfs(const char __user *, struct kstatfs *);
extern int fd_statfs(int, struct kstatfs *);
extern int vfs_ustat(dev_t, struct kstatfs *);
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
extern bool our_mnt(struct vfsmount *mnt);

extern int current_umask(void);

/* /sys/fs */
extern struct kobject *fs_kobj;

#define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
extern int rw_verify_area(int, struct file *, loff_t *, size_t);

#define FLOCK_VERIFY_READ  1
#define FLOCK_VERIFY_WRITE 2

#ifdef CONFIG_FILE_LOCKING
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.
 */

static inline int __mandatory_lock(struct inode *ino)
{
    return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
}

/*
 * ... and these candidates should be on MS_MANDLOCK mounted fs,
 * otherwise these will be advisory locks
 */

static inline int mandatory_lock(struct inode *ino)
{
    return IS_MANDLOCK(ino) && __mandatory_lock(ino);
}

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_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;
}

static inline int break_lease(struct inode *inode, unsigned int mode)
{
    if (inode->i_flock)
        return __break_lease(inode, mode);
    return 0;
}
#else /* !CONFIG_FILE_LOCKING */
static inline int locks_mandatory_locked(struct inode *inode)
{
    return 0;
}

static inline int locks_mandatory_area(int rw, struct inode *inode,
                       struct file *filp, loff_t offset,
                       size_t count)
{
    return 0;
}

static inline int __mandatory_lock(struct inode *inode)
{
    return 0;
}

static inline int mandatory_lock(struct inode *inode)
{
    return 0;
}

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

static inline int locks_verify_truncate(struct inode *inode, struct file *filp,
                    size_t size)
{
    return 0;
}

static inline int break_lease(struct inode *inode, unsigned int mode)
{
    return 0;
}

#endif /* CONFIG_FILE_LOCKING */

/* fs/open.c */
struct audit_names;
struct filename {
    const char      *name;  /* pointer to actual string */
    const __user char   *uptr;  /* original userland pointer */
    struct audit_names  *aname;
    bool            separate; /* should "name" be freed? */
};

extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
               struct file *filp);
extern int do_fallocate(struct file *file, int mode, loff_t offset,
            loff_t len);
extern long do_sys_open(int dfd, const char __user *filename, int flags,
            umode_t mode);
extern struct file *file_open_name(struct filename *, int, umode_t);
extern struct file *filp_open(const char *, int, umode_t);
extern struct file *file_open_root(struct dentry *, struct vfsmount *,
                   const char *, int);
extern struct file * dentry_open(const struct path *, int, const struct cred *);
extern int filp_close(struct file *, fl_owner_t id);

extern struct filename *getname(const char __user *);

enum {
    FILE_CREATED = 1,
    FILE_OPENED = 2
};
extern int finish_open(struct file *file, struct dentry *dentry,
            int (*open)(struct inode *, struct file *),
            int *opened);
extern int finish_no_open(struct file *file, struct dentry *dentry);

/* fs/ioctl.c */

extern int ioctl_preallocate(struct file *filp, void __user *argp);

/* fs/dcache.c */
extern void __init vfs_caches_init_early(void);
extern void __init vfs_caches_init(unsigned long);

extern struct kmem_cache *names_cachep;

extern void final_putname(struct filename *name);

#define __getname()     kmem_cache_alloc(names_cachep, GFP_KERNEL)
#define __putname(name)     kmem_cache_free(names_cachep, (void *)(name))
#ifndef CONFIG_AUDITSYSCALL
#define putname(name)       final_putname(name)
#else
extern void putname(struct filename *name);
#endif

#ifdef CONFIG_BLOCK
extern int register_blkdev(unsigned int, const char *);
extern void unregister_blkdev(unsigned int, const char *);
extern struct block_device *bdget(dev_t);
extern struct block_device *bdgrab(struct block_device *bdev);
extern void bd_set_size(struct block_device *, loff_t size);
extern void bd_forget(struct inode *inode);
extern void bdput(struct block_device *);
extern void invalidate_bdev(struct block_device *);
extern void iterate_bdevs(void (*)(struct block_device *, void *), void *);
extern int sync_blockdev(struct block_device *bdev);
extern void kill_bdev(struct block_device *);
extern struct super_block *freeze_bdev(struct block_device *);
extern void emergency_thaw_all(void);
extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
extern int fsync_bdev(struct block_device *);
#else
static inline void bd_forget(struct inode *inode) {}
static inline int sync_blockdev(struct block_device *bdev) { return 0; }
static inline void kill_bdev(struct block_device *bdev) {}
static inline void invalidate_bdev(struct block_device *bdev) {}

static inline struct super_block *freeze_bdev(struct block_device *sb)
{
    return NULL;
}

static inline int thaw_bdev(struct block_device *bdev, struct super_block *sb)
{
    return 0;
}

static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void *arg)
{
}
#endif
extern int sync_filesystem(struct super_block *);
extern const struct file_operations def_blk_fops;
extern const struct file_operations def_chr_fops;
extern const struct file_operations bad_sock_fops;
extern const struct file_operations def_fifo_fops;
#ifdef CONFIG_BLOCK
extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
extern int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder);
extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
                           void *holder);
extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
                          void *holder);
extern int blkdev_put(struct block_device *bdev, fmode_t mode);
#ifdef CONFIG_SYSFS
extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
extern void bd_unlink_disk_holder(struct block_device *bdev,
                  struct gendisk *disk);
#else
static inline int bd_link_disk_holder(struct block_device *bdev,
                      struct gendisk *disk)
{
    return 0;
}
static inline void bd_unlink_disk_holder(struct block_device *bdev,
                     struct gendisk *disk)
{
}
#endif
#endif

/* fs/char_dev.c */
#define CHRDEV_MAJOR_HASH_SIZE  255
extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
extern int register_chrdev_region(dev_t, unsigned, const char *);
extern int __register_chrdev(unsigned int major, unsigned int baseminor,
                 unsigned int count, const char *name,
                 const struct file_operations *fops);
extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
                unsigned int count, const char *name);
extern void unregister_chrdev_region(dev_t, unsigned);
extern void chrdev_show(struct seq_file *,off_t);

static inline int register_chrdev(unsigned int major, const char *name,
                  const struct file_operations *fops)
{
    return __register_chrdev(major, 0, 256, name, fops);
}

static inline void unregister_chrdev(unsigned int major, const char *name)
{
    __unregister_chrdev(major, 0, 256, name);
}

/* fs/block_dev.c */
#define BDEVNAME_SIZE   32  /* Largest string for a blockdev identifier */
#define BDEVT_SIZE  10  /* Largest string for MAJ:MIN for blkdev */

#ifdef CONFIG_BLOCK
#define BLKDEV_MAJOR_HASH_SIZE  255
extern const char *__bdevname(dev_t, char *buffer);
extern const char *bdevname(struct block_device *bdev, char *buffer);
extern struct block_device *lookup_bdev(const char *);
extern void blkdev_show(struct seq_file *,off_t);

#else
#define BLKDEV_MAJOR_HASH_SIZE  0
#endif

extern void init_special_inode(struct inode *, umode_t, dev_t);

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

extern const struct file_operations read_pipefifo_fops;
extern const struct file_operations write_pipefifo_fops;
extern const struct file_operations rdwr_pipefifo_fops;

#ifdef CONFIG_BLOCK
/*
 * return READ, READA, or WRITE
 */
#define bio_rw(bio)     ((bio)->bi_rw & (RW_MASK | RWA_MASK))

/*
 * return data direction, READ or WRITE
 */
#define bio_data_dir(bio)   ((bio)->bi_rw & 1)

extern void check_disk_size_change(struct gendisk *disk,
                   struct block_device *bdev);
extern int revalidate_disk(struct gendisk *);
extern int check_disk_change(struct block_device *);
extern int __invalidate_device(struct block_device *, bool);
extern int invalidate_partition(struct gendisk *, int);
#endif
unsigned long invalidate_mapping_pages(struct address_space *mapping,
                    pgoff_t start, pgoff_t end);

static inline void invalidate_remote_inode(struct inode *inode)
{
    if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
        S_ISLNK(inode->i_mode))
        invalidate_mapping_pages(inode->i_mapping, 0, -1);
}
extern int invalidate_inode_pages2(struct address_space *mapping);
extern int invalidate_inode_pages2_range(struct address_space *mapping,
                     pgoff_t start, pgoff_t end);
extern int write_inode_now(struct inode *, int);
extern int filemap_fdatawrite(struct address_space *);
extern int filemap_flush(struct address_space *);
extern int filemap_fdatawait(struct address_space *);
extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
                   loff_t lend);
extern int filemap_write_and_wait(struct address_space *mapping);
extern int filemap_write_and_wait_range(struct address_space *mapping,
                        loff_t lstart, loff_t lend);
extern int __filemap_fdatawrite_range(struct address_space *mapping,
                loff_t start, loff_t end, int sync_mode);
extern int filemap_fdatawrite_range(struct address_space *mapping,
                loff_t start, loff_t end);

extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
               int datasync);
extern int vfs_fsync(struct file *file, int datasync);
extern int generic_write_sync(struct file *file, loff_t pos, loff_t count);
extern void emergency_sync(void);
extern void emergency_remount(void);
#ifdef CONFIG_BLOCK
extern sector_t bmap(struct inode *, sector_t);
#endif
extern int notify_change(struct dentry *, struct iattr *);
extern int inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);

static inline bool execute_ok(struct inode *inode)
{
    return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
}

/*
 * get_write_access() gets write permission for a file.
 * put_write_access() releases this write permission.
 * This is used for regular files.
 * We cannot support write (and maybe mmap read-write shared) accesses and
 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
 * can have the following values:
 * 0: no writers, no VM_DENYWRITE mappings
 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
 * > 0: (i_writecount) users are writing to the file.
 *
 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
 * except for the cases where we don't hold i_writecount yet. Then we need to
 * use {get,deny}_write_access() - these functions check the sign and refuse
 * to do the change if sign is wrong.
 */
static inline int get_write_access(struct inode *inode)
{
    return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
}
static inline int deny_write_access(struct file *file)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
}
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_path.dentry->d_inode->i_writecount);
}
#ifdef CONFIG_IMA
static inline void i_readcount_dec(struct inode *inode)
{
    BUG_ON(!atomic_read(&inode->i_readcount));
    atomic_dec(&inode->i_readcount);
}
static inline void i_readcount_inc(struct inode *inode)
{
    atomic_inc(&inode->i_readcount);
}
#else
static inline void i_readcount_dec(struct inode *inode)
{
    return;
}
static inline void i_readcount_inc(struct inode *inode)
{
    return;
}
#endif
extern int do_pipe_flags(int *, int);

extern int kernel_read(struct file *, loff_t, 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 int path_is_under(struct path *, struct path *);
extern ino_t find_inode_number(struct dentry *, struct qstr *);

#include <linux/err.h>

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

extern loff_t vfs_llseek(struct file *file, loff_t offset, int origin);

extern int inode_init_always(struct super_block *, struct inode *);
extern void inode_init_once(struct inode *);
extern void address_space_init_once(struct address_space *mapping);
extern void ihold(struct inode * inode);
extern void iput(struct inode *);
extern struct inode * igrab(struct inode *);
extern ino_t iunique(struct super_block *, ino_t);
extern int inode_needs_sync(struct inode *inode);
extern int generic_delete_inode(struct inode *inode);
static inline int generic_drop_inode(struct inode *inode)
{
    return !inode->i_nlink || inode_unhashed(inode);
}

extern struct inode *ilookup5_nowait(struct super_block *sb,
        unsigned long hashval, int (*test)(struct inode *, void *),
        void *data);
extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
        int (*test)(struct inode *, void *), void *data);
extern struct inode *ilookup(struct super_block *sb, unsigned long ino);

extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
extern struct inode * iget_locked(struct super_block *, unsigned long);
extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
extern int insert_inode_locked(struct inode *);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
#else
static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
#endif
extern void unlock_new_inode(struct inode *);
extern unsigned int get_next_ino(void);

extern void __iget(struct inode * inode);
extern void iget_failed(struct inode *);
extern void clear_inode(struct inode *);
extern void __destroy_inode(struct inode *);
extern struct inode *new_inode_pseudo(struct super_block *sb);
extern struct inode *new_inode(struct super_block *sb);
extern void free_inode_nonrcu(struct inode *inode);
extern int should_remove_suid(struct dentry *);
extern int file_remove_suid(struct file *);

extern void __insert_inode_hash(struct inode *, unsigned long hashval);
static inline void insert_inode_hash(struct inode *inode)
{
    __insert_inode_hash(inode, inode->i_ino);
}

extern void __remove_inode_hash(struct inode *);
static inline void remove_inode_hash(struct inode *inode)
{
    if (!inode_unhashed(inode))
        __remove_inode_hash(inode);
}

extern void inode_sb_list_add(struct inode *inode);

#ifdef CONFIG_BLOCK
extern void submit_bio(int, struct bio *);
extern int bdev_read_only(struct block_device *);
#endif
extern int set_blocksize(struct block_device *, int);
extern int sb_set_blocksize(struct super_block *, int);
extern int sb_min_blocksize(struct super_block *, int);

extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
        unsigned long size, pgoff_t pgoff);
extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
        loff_t *);
extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
        unsigned long *, loff_t, loff_t *, size_t, size_t);
extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
        unsigned long, loff_t, loff_t *, size_t, ssize_t);
extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
extern int generic_segment_checks(const struct iovec *iov,
        unsigned long *nr_segs, size_t *count, int access_flags);

/* fs/block_dev.c */
extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                unsigned long nr_segs, loff_t pos);
extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
            int datasync);
extern void block_sync_page(struct page *page);

/* fs/splice.c */
extern ssize_t generic_file_splice_read(struct file *, loff_t *,
        struct pipe_inode_info *, size_t, unsigned int);
extern ssize_t default_file_splice_read(struct file *, loff_t *,
        struct pipe_inode_info *, size_t, unsigned int);
extern ssize_t generic_file_splice_write(struct pipe_inode_info *,
        struct file *, loff_t *, size_t, unsigned int);
extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
        struct file *out, loff_t *, size_t len, unsigned int flags);
extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
        size_t len, unsigned int flags);

extern void
file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
extern loff_t noop_llseek(struct file *file, loff_t offset, int origin);
extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
        int origin, loff_t maxsize, loff_t eof);
extern int generic_file_open(struct inode * inode, struct file * filp);
extern int nonseekable_open(struct inode * inode, struct file * filp);

#ifdef CONFIG_FS_XIP
extern ssize_t xip_file_read(struct file *filp, char __user *buf, size_t len,
                 loff_t *ppos);
extern int xip_file_mmap(struct file * file, struct vm_area_struct * vma);
extern ssize_t xip_file_write(struct file *filp, const char __user *buf,
                  size_t len, loff_t *ppos);
extern int xip_truncate_page(struct address_space *mapping, loff_t from);
#else
static inline int xip_truncate_page(struct address_space *mapping, loff_t from)
{
    return 0;
}
#endif

#ifdef CONFIG_BLOCK
typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
                loff_t file_offset);

enum {
    /* need locking between buffered and direct access */
    DIO_LOCKING = 0x01,

    /* filesystem does not support filling holes */
    DIO_SKIP_HOLES  = 0x02,
};

void dio_end_io(struct bio *bio, int error);

ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
    struct block_device *bdev, const struct iovec *iov, loff_t offset,
    unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
    dio_submit_t submit_io, int flags);

static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
        struct inode *inode, const struct iovec *iov, loff_t offset,
        unsigned long nr_segs, get_block_t get_block)
{
    return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
                    offset, nr_segs, get_block, NULL, NULL,
                    DIO_LOCKING | DIO_SKIP_HOLES);
}
#endif

void inode_dio_wait(struct inode *inode);
void inode_dio_done(struct inode *inode);

extern const struct file_operations generic_ro_fops;

#define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))

extern int vfs_readlink(struct dentry *, char __user *, int, const char *);
extern int vfs_follow_link(struct nameidata *, const char *);
extern int page_readlink(struct dentry *, char __user *, int);
extern void *page_follow_link_light(struct dentry *, struct nameidata *);
extern void page_put_link(struct dentry *, struct nameidata *, void *);
extern int __page_symlink(struct inode *inode, const char *symname, int len,
        int nofs);
extern int page_symlink(struct inode *inode, const char *symname, int len);
extern const struct inode_operations page_symlink_inode_operations;
extern int generic_readlink(struct dentry *, char __user *, int);
extern void generic_fillattr(struct inode *, struct kstat *);
extern int vfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
void __inode_add_bytes(struct inode *inode, loff_t bytes);
void inode_add_bytes(struct inode *inode, loff_t bytes);
void inode_sub_bytes(struct inode *inode, loff_t bytes);
loff_t inode_get_bytes(struct inode *inode);
void inode_set_bytes(struct inode *inode, loff_t bytes);

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

extern int vfs_stat(const char __user *, struct kstat *);
extern int vfs_lstat(const char __user *, struct kstat *);
extern int vfs_fstat(unsigned int, struct kstat *);
extern int vfs_fstatat(int , const char __user *, struct kstat *, int);

extern int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
            unsigned long arg);
extern int __generic_block_fiemap(struct inode *inode,
                  struct fiemap_extent_info *fieinfo,
                  loff_t start, loff_t len,
                  get_block_t *get_block);
extern int generic_block_fiemap(struct inode *inode,
                struct fiemap_extent_info *fieinfo, u64 start,
                u64 len, get_block_t *get_block);

extern void get_filesystem(struct file_system_type *fs);
extern void put_filesystem(struct file_system_type *fs);
extern struct file_system_type *get_fs_type(const char *name);
extern struct super_block *get_super(struct block_device *);
extern struct super_block *get_super_thawed(struct block_device *);
extern struct super_block *get_active_super(struct block_device *bdev);
extern void drop_super(struct super_block *sb);
extern void iterate_supers(void (*)(struct super_block *, void *), void *);
extern void iterate_supers_type(struct file_system_type *,
                    void (*)(struct super_block *, void *), void *);

extern int dcache_dir_open(struct inode *, struct file *);
extern int dcache_dir_close(struct inode *, struct file *);
extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
extern int dcache_readdir(struct file *, void *, filldir_t);
extern int simple_setattr(struct dentry *, struct iattr *);
extern int simple_getattr(struct vfsmount *, struct dentry *, struct kstat *);
extern int simple_statfs(struct dentry *, struct kstatfs *);
extern int simple_open(struct inode *inode, struct file *file);
extern int simple_link(struct dentry *, struct inode *, struct dentry *);
extern int simple_unlink(struct inode *, struct dentry *);
extern int simple_rmdir(struct inode *, struct dentry *);
extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
extern int noop_fsync(struct file *, loff_t, loff_t, int);
extern int simple_empty(struct dentry *);
extern int simple_readpage(struct file *file, struct page *page);
extern int simple_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata);
extern int simple_write_end(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned copied,
            struct page *page, void *fsdata);

extern struct dentry *simple_lookup(struct inode *, struct dentry *, unsigned int flags);
extern ssize_t generic_read_dir(struct file *, char __user *, size_t, loff_t *);
extern const struct file_operations simple_dir_operations;
extern const struct inode_operations simple_dir_inode_operations;
struct tree_descr { char *name; const struct file_operations *ops; int mode; };
struct dentry *d_alloc_name(struct dentry *, const char *);
extern int simple_fill_super(struct super_block *, unsigned long, struct tree_descr *);
extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
extern void simple_release_fs(struct vfsmount **mount, int *count);

extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
            loff_t *ppos, const void *from, size_t available);
extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
        const void __user *from, size_t count);

extern int generic_file_fsync(struct file *, loff_t, loff_t, int);

extern int generic_check_addressable(unsigned, u64);

#ifdef CONFIG_MIGRATION
extern int buffer_migrate_page(struct address_space *,
                struct page *, struct page *,
                enum migrate_mode);
#else
#define buffer_migrate_page NULL
#endif

extern int inode_change_ok(const struct inode *, struct iattr *);
extern int inode_newsize_ok(const struct inode *, loff_t offset);
extern void setattr_copy(struct inode *inode, const struct iattr *attr);

extern int file_update_time(struct file *file);

extern int generic_show_options(struct seq_file *m, struct dentry *root);
extern void save_mount_options(struct super_block *sb, char *options);
extern void replace_mount_options(struct super_block *sb, char *options);

static inline ino_t parent_ino(struct dentry *dentry)
{
    ino_t res;

    /*
     * Don't strictly need d_lock here? If the parent ino could change
     * then surely we'd have a deeper race in the caller?
     */
    spin_lock(&dentry->d_lock);
    res = dentry->d_parent->d_inode->i_ino;
    spin_unlock(&dentry->d_lock);
    return res;
}

/* Transaction based IO helpers */

/*
 * An argresp is stored in an allocated page and holds the
 * size of the argument or response, along with its content
 */
struct simple_transaction_argresp {
    ssize_t size;
    char data[0];
};

#define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))

char *simple_transaction_get(struct file *file, const char __user *buf,
                size_t size);
ssize_t simple_transaction_read(struct file *file, char __user *buf,
                size_t size, loff_t *pos);
int simple_transaction_release(struct inode *inode, struct file *file);

void simple_transaction_set(struct file *file, size_t n);

/*
 * simple attribute files
 *
 * These attributes behave similar to those in sysfs:
 *
 * Writing to an attribute immediately sets a value, an open file can be
 * written to multiple times.
 *
 * Reading from an attribute creates a buffer from the value that might get
 * read with multiple read calls. When the attribute has been read
 * completely, no further read calls are possible until the file is opened
 * again.
 *
 * All attributes contain a text representation of a numeric value
 * that are accessed with the get() and set() functions.
 */
#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)        \
static int __fops ## _open(struct inode *inode, struct file *file)  \
{                                   \
    __simple_attr_check_format(__fmt, 0ull);            \
    return simple_attr_open(inode, file, __get, __set, __fmt);  \
}                                   \
static const struct file_operations __fops = {              \
    .owner   = THIS_MODULE,                     \
    .open    = __fops ## _open,                 \
    .release = simple_attr_release,                 \
    .read    = simple_attr_read,                    \
    .write   = simple_attr_write,                   \
    .llseek  = generic_file_llseek,                 \
};

static inline __printf(1, 2)
void __simple_attr_check_format(const char *fmt, ...)
{
    /* don't do anything, just let the compiler check the arguments; */
}

int simple_attr_open(struct inode *inode, struct file *file,
             int (*get)(void *, u64 *), int (*set)(void *, u64),
             const char *fmt);
int simple_attr_release(struct inode *inode, struct file *file);
ssize_t simple_attr_read(struct file *file, char __user *buf,
             size_t len, loff_t *ppos);
ssize_t simple_attr_write(struct file *file, const char __user *buf,
              size_t len, loff_t *ppos);

struct ctl_table;
int proc_nr_files(struct ctl_table *table, int write,
          void __user *buffer, size_t *lenp, loff_t *ppos);
int proc_nr_dentry(struct ctl_table *table, int write,
          void __user *buffer, size_t *lenp, loff_t *ppos);
int proc_nr_inodes(struct ctl_table *table, int write,
           void __user *buffer, size_t *lenp, loff_t *ppos);
int __init get_filesystem_list(char *buf);

#define __FMODE_EXEC        ((__force int) FMODE_EXEC)
#define __FMODE_NONOTIFY    ((__force int) FMODE_NONOTIFY)

#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
#define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
                        (flag & __FMODE_NONOTIFY)))

static inline int is_sxid(umode_t mode)
{
    return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
}

static inline void inode_has_no_xattr(struct inode *inode)
{
    if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))
        inode->i_flags |= S_NOSEC;
}

#endif /* _LINUX_FS_H */