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Linux/include/linux/fs.h

  1 #ifndef _LINUX_FS_H
  2 #define _LINUX_FS_H
  3 
  4 
  5 #include <linux/linkage.h>
  6 #include <linux/wait.h>
  7 #include <linux/kdev_t.h>
  8 #include <linux/dcache.h>
  9 #include <linux/path.h>
 10 #include <linux/stat.h>
 11 #include <linux/cache.h>
 12 #include <linux/list.h>
 13 #include <linux/list_lru.h>
 14 #include <linux/llist.h>
 15 #include <linux/radix-tree.h>
 16 #include <linux/rbtree.h>
 17 #include <linux/init.h>
 18 #include <linux/pid.h>
 19 #include <linux/bug.h>
 20 #include <linux/mutex.h>
 21 #include <linux/capability.h>
 22 #include <linux/semaphore.h>
 23 #include <linux/fiemap.h>
 24 #include <linux/rculist_bl.h>
 25 #include <linux/atomic.h>
 26 #include <linux/shrinker.h>
 27 #include <linux/migrate_mode.h>
 28 #include <linux/uidgid.h>
 29 #include <linux/lockdep.h>
 30 #include <linux/percpu-rwsem.h>
 31 #include <linux/blk_types.h>
 32 
 33 #include <asm/byteorder.h>
 34 #include <uapi/linux/fs.h>
 35 
 36 struct export_operations;
 37 struct hd_geometry;
 38 struct iovec;
 39 struct nameidata;
 40 struct kiocb;
 41 struct kobject;
 42 struct pipe_inode_info;
 43 struct poll_table_struct;
 44 struct kstatfs;
 45 struct vm_area_struct;
 46 struct vfsmount;
 47 struct cred;
 48 struct swap_info_struct;
 49 struct seq_file;
 50 struct workqueue_struct;
 51 
 52 extern void __init inode_init(void);
 53 extern void __init inode_init_early(void);
 54 extern void __init files_init(unsigned long);
 55 
 56 extern struct files_stat_struct files_stat;
 57 extern unsigned long get_max_files(void);
 58 extern int sysctl_nr_open;
 59 extern struct inodes_stat_t inodes_stat;
 60 extern int leases_enable, lease_break_time;
 61 extern int sysctl_protected_symlinks;
 62 extern int sysctl_protected_hardlinks;
 63 
 64 struct buffer_head;
 65 typedef int (get_block_t)(struct inode *inode, sector_t iblock,
 66                         struct buffer_head *bh_result, int create);
 67 typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 68                         ssize_t bytes, void *private);
 69 
 70 #define MAY_EXEC                0x00000001
 71 #define MAY_WRITE               0x00000002
 72 #define MAY_READ                0x00000004
 73 #define MAY_APPEND              0x00000008
 74 #define MAY_ACCESS              0x00000010
 75 #define MAY_OPEN                0x00000020
 76 #define MAY_CHDIR               0x00000040
 77 /* called from RCU mode, don't block */
 78 #define MAY_NOT_BLOCK           0x00000080
 79 
 80 /*
 81  * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
 82  * to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
 83  */
 84 
 85 /* file is open for reading */
 86 #define FMODE_READ              ((__force fmode_t)0x1)
 87 /* file is open for writing */
 88 #define FMODE_WRITE             ((__force fmode_t)0x2)
 89 /* file is seekable */
 90 #define FMODE_LSEEK             ((__force fmode_t)0x4)
 91 /* file can be accessed using pread */
 92 #define FMODE_PREAD             ((__force fmode_t)0x8)
 93 /* file can be accessed using pwrite */
 94 #define FMODE_PWRITE            ((__force fmode_t)0x10)
 95 /* File is opened for execution with sys_execve / sys_uselib */
 96 #define FMODE_EXEC              ((__force fmode_t)0x20)
 97 /* File is opened with O_NDELAY (only set for block devices) */
 98 #define FMODE_NDELAY            ((__force fmode_t)0x40)
 99 /* File is opened with O_EXCL (only set for block devices) */
100 #define FMODE_EXCL              ((__force fmode_t)0x80)
101 /* File is opened using open(.., 3, ..) and is writeable only for ioctls
102    (specialy hack for floppy.c) */
103 #define FMODE_WRITE_IOCTL       ((__force fmode_t)0x100)
104 /* 32bit hashes as llseek() offset (for directories) */
105 #define FMODE_32BITHASH         ((__force fmode_t)0x200)
106 /* 64bit hashes as llseek() offset (for directories) */
107 #define FMODE_64BITHASH         ((__force fmode_t)0x400)
108 
109 /*
110  * Don't update ctime and mtime.
111  *
112  * Currently a special hack for the XFS open_by_handle ioctl, but we'll
113  * hopefully graduate it to a proper O_CMTIME flag supported by open(2) soon.
114  */
115 #define FMODE_NOCMTIME          ((__force fmode_t)0x800)
116 
117 /* Expect random access pattern */
118 #define FMODE_RANDOM            ((__force fmode_t)0x1000)
119 
120 /* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
121 #define FMODE_UNSIGNED_OFFSET   ((__force fmode_t)0x2000)
122 
123 /* File is opened with O_PATH; almost nothing can be done with it */
124 #define FMODE_PATH              ((__force fmode_t)0x4000)
125 
126 /* File needs atomic accesses to f_pos */
127 #define FMODE_ATOMIC_POS        ((__force fmode_t)0x8000)
128 
129 /* File was opened by fanotify and shouldn't generate fanotify events */
130 #define FMODE_NONOTIFY          ((__force fmode_t)0x1000000)
131 
132 /*
133  * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
134  * that indicates that they should check the contents of the iovec are
135  * valid, but not check the memory that the iovec elements
136  * points too.
137  */
138 #define CHECK_IOVEC_ONLY -1
139 
140 /*
141  * The below are the various read and write types that we support. Some of
142  * them include behavioral modifiers that send information down to the
143  * block layer and IO scheduler. Terminology:
144  *
145  *      The block layer uses device plugging to defer IO a little bit, in
146  *      the hope that we will see more IO very shortly. This increases
147  *      coalescing of adjacent IO and thus reduces the number of IOs we
148  *      have to send to the device. It also allows for better queuing,
149  *      if the IO isn't mergeable. If the caller is going to be waiting
150  *      for the IO, then he must ensure that the device is unplugged so
151  *      that the IO is dispatched to the driver.
152  *
153  *      All IO is handled async in Linux. This is fine for background
154  *      writes, but for reads or writes that someone waits for completion
155  *      on, we want to notify the block layer and IO scheduler so that they
156  *      know about it. That allows them to make better scheduling
157  *      decisions. So when the below references 'sync' and 'async', it
158  *      is referencing this priority hint.
159  *
160  * With that in mind, the available types are:
161  *
162  * READ                 A normal read operation. Device will be plugged.
163  * READ_SYNC            A synchronous read. Device is not plugged, caller can
164  *                      immediately wait on this read without caring about
165  *                      unplugging.
166  * READA                Used for read-ahead operations. Lower priority, and the
167  *                      block layer could (in theory) choose to ignore this
168  *                      request if it runs into resource problems.
169  * WRITE                A normal async write. Device will be plugged.
170  * WRITE_SYNC           Synchronous write. Identical to WRITE, but passes down
171  *                      the hint that someone will be waiting on this IO
172  *                      shortly. The write equivalent of READ_SYNC.
173  * WRITE_ODIRECT        Special case write for O_DIRECT only.
174  * WRITE_FLUSH          Like WRITE_SYNC but with preceding cache flush.
175  * WRITE_FUA            Like WRITE_SYNC but data is guaranteed to be on
176  *                      non-volatile media on completion.
177  * WRITE_FLUSH_FUA      Combination of WRITE_FLUSH and FUA. The IO is preceded
178  *                      by a cache flush and data is guaranteed to be on
179  *                      non-volatile media on completion.
180  *
181  */
182 #define RW_MASK                 REQ_WRITE
183 #define RWA_MASK                REQ_RAHEAD
184 
185 #define READ                    0
186 #define WRITE                   RW_MASK
187 #define READA                   RWA_MASK
188 #define KERNEL_READ             (READ|REQ_KERNEL)
189 #define KERNEL_WRITE            (WRITE|REQ_KERNEL)
190 
191 #define READ_SYNC               (READ | REQ_SYNC)
192 #define WRITE_SYNC              (WRITE | REQ_SYNC | REQ_NOIDLE)
193 #define WRITE_ODIRECT           (WRITE | REQ_SYNC)
194 #define WRITE_FLUSH             (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH)
195 #define WRITE_FUA               (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FUA)
196 #define WRITE_FLUSH_FUA         (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
197 
198 /*
199  * Attribute flags.  These should be or-ed together to figure out what
200  * has been changed!
201  */
202 #define ATTR_MODE       (1 << 0)
203 #define ATTR_UID        (1 << 1)
204 #define ATTR_GID        (1 << 2)
205 #define ATTR_SIZE       (1 << 3)
206 #define ATTR_ATIME      (1 << 4)
207 #define ATTR_MTIME      (1 << 5)
208 #define ATTR_CTIME      (1 << 6)
209 #define ATTR_ATIME_SET  (1 << 7)
210 #define ATTR_MTIME_SET  (1 << 8)
211 #define ATTR_FORCE      (1 << 9) /* Not a change, but a change it */
212 #define ATTR_ATTR_FLAG  (1 << 10)
213 #define ATTR_KILL_SUID  (1 << 11)
214 #define ATTR_KILL_SGID  (1 << 12)
215 #define ATTR_FILE       (1 << 13)
216 #define ATTR_KILL_PRIV  (1 << 14)
217 #define ATTR_OPEN       (1 << 15) /* Truncating from open(O_TRUNC) */
218 #define ATTR_TIMES_SET  (1 << 16)
219 
220 /*
221  * This is the Inode Attributes structure, used for notify_change().  It
222  * uses the above definitions as flags, to know which values have changed.
223  * Also, in this manner, a Filesystem can look at only the values it cares
224  * about.  Basically, these are the attributes that the VFS layer can
225  * request to change from the FS layer.
226  *
227  * Derek Atkins <warlord@MIT.EDU> 94-10-20
228  */
229 struct iattr {
230         unsigned int    ia_valid;
231         umode_t         ia_mode;
232         kuid_t          ia_uid;
233         kgid_t          ia_gid;
234         loff_t          ia_size;
235         struct timespec ia_atime;
236         struct timespec ia_mtime;
237         struct timespec ia_ctime;
238 
239         /*
240          * Not an attribute, but an auxiliary info for filesystems wanting to
241          * implement an ftruncate() like method.  NOTE: filesystem should
242          * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
243          */
244         struct file     *ia_file;
245 };
246 
247 /*
248  * Includes for diskquotas.
249  */
250 #include <linux/quota.h>
251 
252 /** 
253  * enum positive_aop_returns - aop return codes with specific semantics
254  *
255  * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
256  *                          completed, that the page is still locked, and
257  *                          should be considered active.  The VM uses this hint
258  *                          to return the page to the active list -- it won't
259  *                          be a candidate for writeback again in the near
260  *                          future.  Other callers must be careful to unlock
261  *                          the page if they get this return.  Returned by
262  *                          writepage(); 
263  *
264  * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
265  *                      unlocked it and the page might have been truncated.
266  *                      The caller should back up to acquiring a new page and
267  *                      trying again.  The aop will be taking reasonable
268  *                      precautions not to livelock.  If the caller held a page
269  *                      reference, it should drop it before retrying.  Returned
270  *                      by readpage().
271  *
272  * address_space_operation functions return these large constants to indicate
273  * special semantics to the caller.  These are much larger than the bytes in a
274  * page to allow for functions that return the number of bytes operated on in a
275  * given page.
276  */
277 
278 enum positive_aop_returns {
279         AOP_WRITEPAGE_ACTIVATE  = 0x80000,
280         AOP_TRUNCATED_PAGE      = 0x80001,
281 };
282 
283 #define AOP_FLAG_UNINTERRUPTIBLE        0x0001 /* will not do a short write */
284 #define AOP_FLAG_CONT_EXPAND            0x0002 /* called from cont_expand */
285 #define AOP_FLAG_NOFS                   0x0004 /* used by filesystem to direct
286                                                 * helper code (eg buffer layer)
287                                                 * to clear GFP_FS from alloc */
288 
289 /*
290  * oh the beauties of C type declarations.
291  */
292 struct page;
293 struct address_space;
294 struct writeback_control;
295 
296 struct iov_iter {
297         const struct iovec *iov;
298         unsigned long nr_segs;
299         size_t iov_offset;
300         size_t count;
301 };
302 
303 size_t iov_iter_copy_from_user_atomic(struct page *page,
304                 struct iov_iter *i, unsigned long offset, size_t bytes);
305 size_t iov_iter_copy_from_user(struct page *page,
306                 struct iov_iter *i, unsigned long offset, size_t bytes);
307 void iov_iter_advance(struct iov_iter *i, size_t bytes);
308 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
309 size_t iov_iter_single_seg_count(const struct iov_iter *i);
310 
311 static inline void iov_iter_init(struct iov_iter *i,
312                         const struct iovec *iov, unsigned long nr_segs,
313                         size_t count, size_t written)
314 {
315         i->iov = iov;
316         i->nr_segs = nr_segs;
317         i->iov_offset = 0;
318         i->count = count + written;
319 
320         iov_iter_advance(i, written);
321 }
322 
323 static inline size_t iov_iter_count(struct iov_iter *i)
324 {
325         return i->count;
326 }
327 
328 /*
329  * "descriptor" for what we're up to with a read.
330  * This allows us to use the same read code yet
331  * have multiple different users of the data that
332  * we read from a file.
333  *
334  * The simplest case just copies the data to user
335  * mode.
336  */
337 typedef struct {
338         size_t written;
339         size_t count;
340         union {
341                 char __user *buf;
342                 void *data;
343         } arg;
344         int error;
345 } read_descriptor_t;
346 
347 typedef int (*read_actor_t)(read_descriptor_t *, struct page *,
348                 unsigned long, unsigned long);
349 
350 struct address_space_operations {
351         int (*writepage)(struct page *page, struct writeback_control *wbc);
352         int (*readpage)(struct file *, struct page *);
353 
354         /* Write back some dirty pages from this mapping. */
355         int (*writepages)(struct address_space *, struct writeback_control *);
356 
357         /* Set a page dirty.  Return true if this dirtied it */
358         int (*set_page_dirty)(struct page *page);
359 
360         int (*readpages)(struct file *filp, struct address_space *mapping,
361                         struct list_head *pages, unsigned nr_pages);
362 
363         int (*write_begin)(struct file *, struct address_space *mapping,
364                                 loff_t pos, unsigned len, unsigned flags,
365                                 struct page **pagep, void **fsdata);
366         int (*write_end)(struct file *, struct address_space *mapping,
367                                 loff_t pos, unsigned len, unsigned copied,
368                                 struct page *page, void *fsdata);
369 
370         /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
371         sector_t (*bmap)(struct address_space *, sector_t);
372         void (*invalidatepage) (struct page *, unsigned int, unsigned int);
373         int (*releasepage) (struct page *, gfp_t);
374         void (*freepage)(struct page *);
375         ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
376                         loff_t offset, unsigned long nr_segs);
377         int (*get_xip_mem)(struct address_space *, pgoff_t, int,
378                                                 void **, unsigned long *);
379         /*
380          * migrate the contents of a page to the specified target. If
381          * migrate_mode is MIGRATE_ASYNC, it must not block.
382          */
383         int (*migratepage) (struct address_space *,
384                         struct page *, struct page *, enum migrate_mode);
385         int (*launder_page) (struct page *);
386         int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
387                                         unsigned long);
388         void (*is_dirty_writeback) (struct page *, bool *, bool *);
389         int (*error_remove_page)(struct address_space *, struct page *);
390 
391         /* swapfile support */
392         int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
393                                 sector_t *span);
394         void (*swap_deactivate)(struct file *file);
395 };
396 
397 extern const struct address_space_operations empty_aops;
398 
399 /*
400  * pagecache_write_begin/pagecache_write_end must be used by general code
401  * to write into the pagecache.
402  */
403 int pagecache_write_begin(struct file *, struct address_space *mapping,
404                                 loff_t pos, unsigned len, unsigned flags,
405                                 struct page **pagep, void **fsdata);
406 
407 int pagecache_write_end(struct file *, struct address_space *mapping,
408                                 loff_t pos, unsigned len, unsigned copied,
409                                 struct page *page, void *fsdata);
410 
411 struct backing_dev_info;
412 struct address_space {
413         struct inode            *host;          /* owner: inode, block_device */
414         struct radix_tree_root  page_tree;      /* radix tree of all pages */
415         spinlock_t              tree_lock;      /* and lock protecting it */
416         unsigned int            i_mmap_writable;/* count VM_SHARED mappings */
417         struct rb_root          i_mmap;         /* tree of private and shared mappings */
418         struct list_head        i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
419         struct mutex            i_mmap_mutex;   /* protect tree, count, list */
420         /* Protected by tree_lock together with the radix tree */
421         unsigned long           nrpages;        /* number of total pages */
422         pgoff_t                 writeback_index;/* writeback starts here */
423         const struct address_space_operations *a_ops;   /* methods */
424         unsigned long           flags;          /* error bits/gfp mask */
425         struct backing_dev_info *backing_dev_info; /* device readahead, etc */
426         spinlock_t              private_lock;   /* for use by the address_space */
427         struct list_head        private_list;   /* ditto */
428         void                    *private_data;  /* ditto */
429 } __attribute__((aligned(sizeof(long))));
430         /*
431          * On most architectures that alignment is already the case; but
432          * must be enforced here for CRIS, to let the least significant bit
433          * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
434          */
435 struct request_queue;
436 
437 struct block_device {
438         dev_t                   bd_dev;  /* not a kdev_t - it's a search key */
439         int                     bd_openers;
440         struct inode *          bd_inode;       /* will die */
441         struct super_block *    bd_super;
442         struct mutex            bd_mutex;       /* open/close mutex */
443         struct list_head        bd_inodes;
444         void *                  bd_claiming;
445         void *                  bd_holder;
446         int                     bd_holders;
447         bool                    bd_write_holder;
448 #ifdef CONFIG_SYSFS
449         struct list_head        bd_holder_disks;
450 #endif
451         struct block_device *   bd_contains;
452         unsigned                bd_block_size;
453         struct hd_struct *      bd_part;
454         /* number of times partitions within this device have been opened. */
455         unsigned                bd_part_count;
456         int                     bd_invalidated;
457         struct gendisk *        bd_disk;
458         struct request_queue *  bd_queue;
459         struct list_head        bd_list;
460         /*
461          * Private data.  You must have bd_claim'ed the block_device
462          * to use this.  NOTE:  bd_claim allows an owner to claim
463          * the same device multiple times, the owner must take special
464          * care to not mess up bd_private for that case.
465          */
466         unsigned long           bd_private;
467 
468         /* The counter of freeze processes */
469         int                     bd_fsfreeze_count;
470         /* Mutex for freeze */
471         struct mutex            bd_fsfreeze_mutex;
472 };
473 
474 /*
475  * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
476  * radix trees
477  */
478 #define PAGECACHE_TAG_DIRTY     0
479 #define PAGECACHE_TAG_WRITEBACK 1
480 #define PAGECACHE_TAG_TOWRITE   2
481 
482 int mapping_tagged(struct address_space *mapping, int tag);
483 
484 /*
485  * Might pages of this file be mapped into userspace?
486  */
487 static inline int mapping_mapped(struct address_space *mapping)
488 {
489         return  !RB_EMPTY_ROOT(&mapping->i_mmap) ||
490                 !list_empty(&mapping->i_mmap_nonlinear);
491 }
492 
493 /*
494  * Might pages of this file have been modified in userspace?
495  * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
496  * marks vma as VM_SHARED if it is shared, and the file was opened for
497  * writing i.e. vma may be mprotected writable even if now readonly.
498  */
499 static inline int mapping_writably_mapped(struct address_space *mapping)
500 {
501         return mapping->i_mmap_writable != 0;
502 }
503 
504 /*
505  * Use sequence counter to get consistent i_size on 32-bit processors.
506  */
507 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
508 #include <linux/seqlock.h>
509 #define __NEED_I_SIZE_ORDERED
510 #define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
511 #else
512 #define i_size_ordered_init(inode) do { } while (0)
513 #endif
514 
515 struct posix_acl;
516 #define ACL_NOT_CACHED ((void *)(-1))
517 
518 #define IOP_FASTPERM    0x0001
519 #define IOP_LOOKUP      0x0002
520 #define IOP_NOFOLLOW    0x0004
521 
522 /*
523  * Keep mostly read-only and often accessed (especially for
524  * the RCU path lookup and 'stat' data) fields at the beginning
525  * of the 'struct inode'
526  */
527 struct inode {
528         umode_t                 i_mode;
529         unsigned short          i_opflags;
530         kuid_t                  i_uid;
531         kgid_t                  i_gid;
532         unsigned int            i_flags;
533 
534 #ifdef CONFIG_FS_POSIX_ACL
535         struct posix_acl        *i_acl;
536         struct posix_acl        *i_default_acl;
537 #endif
538 
539         const struct inode_operations   *i_op;
540         struct super_block      *i_sb;
541         struct address_space    *i_mapping;
542 
543 #ifdef CONFIG_SECURITY
544         void                    *i_security;
545 #endif
546 
547         /* Stat data, not accessed from path walking */
548         unsigned long           i_ino;
549         /*
550          * Filesystems may only read i_nlink directly.  They shall use the
551          * following functions for modification:
552          *
553          *    (set|clear|inc|drop)_nlink
554          *    inode_(inc|dec)_link_count
555          */
556         union {
557                 const unsigned int i_nlink;
558                 unsigned int __i_nlink;
559         };
560         dev_t                   i_rdev;
561         loff_t                  i_size;
562         struct timespec         i_atime;
563         struct timespec         i_mtime;
564         struct timespec         i_ctime;
565         spinlock_t              i_lock; /* i_blocks, i_bytes, maybe i_size */
566         unsigned short          i_bytes;
567         unsigned int            i_blkbits;
568         blkcnt_t                i_blocks;
569 
570 #ifdef __NEED_I_SIZE_ORDERED
571         seqcount_t              i_size_seqcount;
572 #endif
573 
574         /* Misc */
575         unsigned long           i_state;
576         struct mutex            i_mutex;
577 
578         unsigned long           dirtied_when;   /* jiffies of first dirtying */
579 
580         struct hlist_node       i_hash;
581         struct list_head        i_wb_list;      /* backing dev IO list */
582         struct list_head        i_lru;          /* inode LRU list */
583         struct list_head        i_sb_list;
584         union {
585                 struct hlist_head       i_dentry;
586                 struct rcu_head         i_rcu;
587         };
588         u64                     i_version;
589         atomic_t                i_count;
590         atomic_t                i_dio_count;
591         atomic_t                i_writecount;
592         const struct file_operations    *i_fop; /* former ->i_op->default_file_ops */
593         struct file_lock        *i_flock;
594         struct address_space    i_data;
595 #ifdef CONFIG_QUOTA
596         struct dquot            *i_dquot[MAXQUOTAS];
597 #endif
598         struct list_head        i_devices;
599         union {
600                 struct pipe_inode_info  *i_pipe;
601                 struct block_device     *i_bdev;
602                 struct cdev             *i_cdev;
603         };
604 
605         __u32                   i_generation;
606 
607 #ifdef CONFIG_FSNOTIFY
608         __u32                   i_fsnotify_mask; /* all events this inode cares about */
609         struct hlist_head       i_fsnotify_marks;
610 #endif
611 
612 #ifdef CONFIG_IMA
613         atomic_t                i_readcount; /* struct files open RO */
614 #endif
615         void                    *i_private; /* fs or device private pointer */
616 };
617 
618 static inline int inode_unhashed(struct inode *inode)
619 {
620         return hlist_unhashed(&inode->i_hash);
621 }
622 
623 /*
624  * inode->i_mutex nesting subclasses for the lock validator:
625  *
626  * 0: the object of the current VFS operation
627  * 1: parent
628  * 2: child/target
629  * 3: xattr
630  * 4: second non-directory
631  * The last is for certain operations (such as rename) which lock two
632  * non-directories at once.
633  *
634  * The locking order between these classes is
635  * parent -> child -> normal -> xattr -> second non-directory
636  */
637 enum inode_i_mutex_lock_class
638 {
639         I_MUTEX_NORMAL,
640         I_MUTEX_PARENT,
641         I_MUTEX_CHILD,
642         I_MUTEX_XATTR,
643         I_MUTEX_NONDIR2
644 };
645 
646 void lock_two_nondirectories(struct inode *, struct inode*);
647 void unlock_two_nondirectories(struct inode *, struct inode*);
648 
649 /*
650  * NOTE: in a 32bit arch with a preemptable kernel and
651  * an UP compile the i_size_read/write must be atomic
652  * with respect to the local cpu (unlike with preempt disabled),
653  * but they don't need to be atomic with respect to other cpus like in
654  * true SMP (so they need either to either locally disable irq around
655  * the read or for example on x86 they can be still implemented as a
656  * cmpxchg8b without the need of the lock prefix). For SMP compiles
657  * and 64bit archs it makes no difference if preempt is enabled or not.
658  */
659 static inline loff_t i_size_read(const struct inode *inode)
660 {
661 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
662         loff_t i_size;
663         unsigned int seq;
664 
665         do {
666                 seq = read_seqcount_begin(&inode->i_size_seqcount);
667                 i_size = inode->i_size;
668         } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
669         return i_size;
670 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
671         loff_t i_size;
672 
673         preempt_disable();
674         i_size = inode->i_size;
675         preempt_enable();
676         return i_size;
677 #else
678         return inode->i_size;
679 #endif
680 }
681 
682 /*
683  * NOTE: unlike i_size_read(), i_size_write() does need locking around it
684  * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
685  * can be lost, resulting in subsequent i_size_read() calls spinning forever.
686  */
687 static inline void i_size_write(struct inode *inode, loff_t i_size)
688 {
689 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
690         preempt_disable();
691         write_seqcount_begin(&inode->i_size_seqcount);
692         inode->i_size = i_size;
693         write_seqcount_end(&inode->i_size_seqcount);
694         preempt_enable();
695 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
696         preempt_disable();
697         inode->i_size = i_size;
698         preempt_enable();
699 #else
700         inode->i_size = i_size;
701 #endif
702 }
703 
704 /* Helper functions so that in most cases filesystems will
705  * not need to deal directly with kuid_t and kgid_t and can
706  * instead deal with the raw numeric values that are stored
707  * in the filesystem.
708  */
709 static inline uid_t i_uid_read(const struct inode *inode)
710 {
711         return from_kuid(&init_user_ns, inode->i_uid);
712 }
713 
714 static inline gid_t i_gid_read(const struct inode *inode)
715 {
716         return from_kgid(&init_user_ns, inode->i_gid);
717 }
718 
719 static inline void i_uid_write(struct inode *inode, uid_t uid)
720 {
721         inode->i_uid = make_kuid(&init_user_ns, uid);
722 }
723 
724 static inline void i_gid_write(struct inode *inode, gid_t gid)
725 {
726         inode->i_gid = make_kgid(&init_user_ns, gid);
727 }
728 
729 static inline unsigned iminor(const struct inode *inode)
730 {
731         return MINOR(inode->i_rdev);
732 }
733 
734 static inline unsigned imajor(const struct inode *inode)
735 {
736         return MAJOR(inode->i_rdev);
737 }
738 
739 extern struct block_device *I_BDEV(struct inode *inode);
740 
741 struct fown_struct {
742         rwlock_t lock;          /* protects pid, uid, euid fields */
743         struct pid *pid;        /* pid or -pgrp where SIGIO should be sent */
744         enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
745         kuid_t uid, euid;       /* uid/euid of process setting the owner */
746         int signum;             /* posix.1b rt signal to be delivered on IO */
747 };
748 
749 /*
750  * Track a single file's readahead state
751  */
752 struct file_ra_state {
753         pgoff_t start;                  /* where readahead started */
754         unsigned int size;              /* # of readahead pages */
755         unsigned int async_size;        /* do asynchronous readahead when
756                                            there are only # of pages ahead */
757 
758         unsigned int ra_pages;          /* Maximum readahead window */
759         unsigned int mmap_miss;         /* Cache miss stat for mmap accesses */
760         loff_t prev_pos;                /* Cache last read() position */
761 };
762 
763 /*
764  * Check if @index falls in the readahead windows.
765  */
766 static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
767 {
768         return (index >= ra->start &&
769                 index <  ra->start + ra->size);
770 }
771 
772 #define FILE_MNT_WRITE_TAKEN    1
773 #define FILE_MNT_WRITE_RELEASED 2
774 
775 struct file {
776         union {
777                 struct llist_node       fu_llist;
778                 struct rcu_head         fu_rcuhead;
779         } f_u;
780         struct path             f_path;
781 #define f_dentry        f_path.dentry
782         struct inode            *f_inode;       /* cached value */
783         const struct file_operations    *f_op;
784 
785         /*
786          * Protects f_ep_links, f_flags.
787          * Must not be taken from IRQ context.
788          */
789         spinlock_t              f_lock;
790         atomic_long_t           f_count;
791         unsigned int            f_flags;
792         fmode_t                 f_mode;
793         struct mutex            f_pos_lock;
794         loff_t                  f_pos;
795         struct fown_struct      f_owner;
796         const struct cred       *f_cred;
797         struct file_ra_state    f_ra;
798 
799         u64                     f_version;
800 #ifdef CONFIG_SECURITY
801         void                    *f_security;
802 #endif
803         /* needed for tty driver, and maybe others */
804         void                    *private_data;
805 
806 #ifdef CONFIG_EPOLL
807         /* Used by fs/eventpoll.c to link all the hooks to this file */
808         struct list_head        f_ep_links;
809         struct list_head        f_tfile_llink;
810 #endif /* #ifdef CONFIG_EPOLL */
811         struct address_space    *f_mapping;
812 #ifdef CONFIG_DEBUG_WRITECOUNT
813         unsigned long f_mnt_write_state;
814 #endif
815 } __attribute__((aligned(4)));  /* lest something weird decides that 2 is OK */
816 
817 struct file_handle {
818         __u32 handle_bytes;
819         int handle_type;
820         /* file identifier */
821         unsigned char f_handle[0];
822 };
823 
824 static inline struct file *get_file(struct file *f)
825 {
826         atomic_long_inc(&f->f_count);
827         return f;
828 }
829 #define fput_atomic(x)  atomic_long_add_unless(&(x)->f_count, -1, 1)
830 #define file_count(x)   atomic_long_read(&(x)->f_count)
831 
832 #ifdef CONFIG_DEBUG_WRITECOUNT
833 static inline void file_take_write(struct file *f)
834 {
835         WARN_ON(f->f_mnt_write_state != 0);
836         f->f_mnt_write_state = FILE_MNT_WRITE_TAKEN;
837 }
838 static inline void file_release_write(struct file *f)
839 {
840         f->f_mnt_write_state |= FILE_MNT_WRITE_RELEASED;
841 }
842 static inline void file_reset_write(struct file *f)
843 {
844         f->f_mnt_write_state = 0;
845 }
846 static inline void file_check_state(struct file *f)
847 {
848         /*
849          * At this point, either both or neither of these bits
850          * should be set.
851          */
852         WARN_ON(f->f_mnt_write_state == FILE_MNT_WRITE_TAKEN);
853         WARN_ON(f->f_mnt_write_state == FILE_MNT_WRITE_RELEASED);
854 }
855 static inline int file_check_writeable(struct file *f)
856 {
857         if (f->f_mnt_write_state == FILE_MNT_WRITE_TAKEN)
858                 return 0;
859         printk(KERN_WARNING "writeable file with no "
860                             "mnt_want_write()\n");
861         WARN_ON(1);
862         return -EINVAL;
863 }
864 #else /* !CONFIG_DEBUG_WRITECOUNT */
865 static inline void file_take_write(struct file *filp) {}
866 static inline void file_release_write(struct file *filp) {}
867 static inline void file_reset_write(struct file *filp) {}
868 static inline void file_check_state(struct file *filp) {}
869 static inline int file_check_writeable(struct file *filp)
870 {
871         return 0;
872 }
873 #endif /* CONFIG_DEBUG_WRITECOUNT */
874 
875 #define MAX_NON_LFS     ((1UL<<31) - 1)
876 
877 /* Page cache limit. The filesystems should put that into their s_maxbytes 
878    limits, otherwise bad things can happen in VM. */ 
879 #if BITS_PER_LONG==32
880 #define MAX_LFS_FILESIZE        (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1) 
881 #elif BITS_PER_LONG==64
882 #define MAX_LFS_FILESIZE        ((loff_t)0x7fffffffffffffffLL)
883 #endif
884 
885 #define FL_POSIX        1
886 #define FL_FLOCK        2
887 #define FL_DELEG        4       /* NFSv4 delegation */
888 #define FL_ACCESS       8       /* not trying to lock, just looking */
889 #define FL_EXISTS       16      /* when unlocking, test for existence */
890 #define FL_LEASE        32      /* lease held on this file */
891 #define FL_CLOSE        64      /* unlock on close */
892 #define FL_SLEEP        128     /* A blocking lock */
893 #define FL_DOWNGRADE_PENDING    256 /* Lease is being downgraded */
894 #define FL_UNLOCK_PENDING       512 /* Lease is being broken */
895 
896 /*
897  * Special return value from posix_lock_file() and vfs_lock_file() for
898  * asynchronous locking.
899  */
900 #define FILE_LOCK_DEFERRED 1
901 
902 /*
903  * The POSIX file lock owner is determined by
904  * the "struct files_struct" in the thread group
905  * (or NULL for no owner - BSD locks).
906  *
907  * Lockd stuffs a "host" pointer into this.
908  */
909 typedef struct files_struct *fl_owner_t;
910 
911 struct file_lock_operations {
912         void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
913         void (*fl_release_private)(struct file_lock *);
914 };
915 
916 struct lock_manager_operations {
917         int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
918         unsigned long (*lm_owner_key)(struct file_lock *);
919         void (*lm_notify)(struct file_lock *);  /* unblock callback */
920         int (*lm_grant)(struct file_lock *, struct file_lock *, int);
921         void (*lm_break)(struct file_lock *);
922         int (*lm_change)(struct file_lock **, int);
923 };
924 
925 struct lock_manager {
926         struct list_head list;
927 };
928 
929 struct net;
930 void locks_start_grace(struct net *, struct lock_manager *);
931 void locks_end_grace(struct lock_manager *);
932 int locks_in_grace(struct net *);
933 
934 /* that will die - we need it for nfs_lock_info */
935 #include <linux/nfs_fs_i.h>
936 
937 /*
938  * struct file_lock represents a generic "file lock". It's used to represent
939  * POSIX byte range locks, BSD (flock) locks, and leases. It's important to
940  * note that the same struct is used to represent both a request for a lock and
941  * the lock itself, but the same object is never used for both.
942  *
943  * FIXME: should we create a separate "struct lock_request" to help distinguish
944  * these two uses?
945  *
946  * The i_flock list is ordered by:
947  *
948  * 1) lock type -- FL_LEASEs first, then FL_FLOCK, and finally FL_POSIX
949  * 2) lock owner
950  * 3) lock range start
951  * 4) lock range end
952  *
953  * Obviously, the last two criteria only matter for POSIX locks.
954  */
955 struct file_lock {
956         struct file_lock *fl_next;      /* singly linked list for this inode  */
957         struct hlist_node fl_link;      /* node in global lists */
958         struct list_head fl_block;      /* circular list of blocked processes */
959         fl_owner_t fl_owner;
960         unsigned int fl_flags;
961         unsigned char fl_type;
962         unsigned int fl_pid;
963         int fl_link_cpu;                /* what cpu's list is this on? */
964         struct pid *fl_nspid;
965         wait_queue_head_t fl_wait;
966         struct file *fl_file;
967         loff_t fl_start;
968         loff_t fl_end;
969 
970         struct fasync_struct *  fl_fasync; /* for lease break notifications */
971         /* for lease breaks: */
972         unsigned long fl_break_time;
973         unsigned long fl_downgrade_time;
974 
975         const struct file_lock_operations *fl_ops;      /* Callbacks for filesystems */
976         const struct lock_manager_operations *fl_lmops; /* Callbacks for lockmanagers */
977         union {
978                 struct nfs_lock_info    nfs_fl;
979                 struct nfs4_lock_info   nfs4_fl;
980                 struct {
981                         struct list_head link;  /* link in AFS vnode's pending_locks list */
982                         int state;              /* state of grant or error if -ve */
983                 } afs;
984         } fl_u;
985 };
986 
987 /* The following constant reflects the upper bound of the file/locking space */
988 #ifndef OFFSET_MAX
989 #define INT_LIMIT(x)    (~((x)1 << (sizeof(x)*8 - 1)))
990 #define OFFSET_MAX      INT_LIMIT(loff_t)
991 #define OFFT_OFFSET_MAX INT_LIMIT(off_t)
992 #endif
993 
994 #include <linux/fcntl.h>
995 
996 extern void send_sigio(struct fown_struct *fown, int fd, int band);
997 
998 #ifdef CONFIG_FILE_LOCKING
999 extern int fcntl_getlk(struct file *, struct flock __user *);
1000 extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
1001                         struct flock __user *);
1002 
1003 #if BITS_PER_LONG == 32
1004 extern int fcntl_getlk64(struct file *, struct flock64 __user *);
1005 extern int fcntl_setlk64(unsigned int, struct file *, unsigned int,
1006                         struct flock64 __user *);
1007 #endif
1008 
1009 extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
1010 extern int fcntl_getlease(struct file *filp);
1011 
1012 /* fs/locks.c */
1013 void locks_free_lock(struct file_lock *fl);
1014 extern void locks_init_lock(struct file_lock *);
1015 extern struct file_lock * locks_alloc_lock(void);
1016 extern void locks_copy_lock(struct file_lock *, struct file_lock *);
1017 extern void __locks_copy_lock(struct file_lock *, const struct file_lock *);
1018 extern void locks_remove_posix(struct file *, fl_owner_t);
1019 extern void locks_remove_flock(struct file *);
1020 extern void locks_release_private(struct file_lock *);
1021 extern void posix_test_lock(struct file *, struct file_lock *);
1022 extern int posix_lock_file(struct file *, struct file_lock *, struct file_lock *);
1023 extern int posix_lock_file_wait(struct file *, struct file_lock *);
1024 extern int posix_unblock_lock(struct file_lock *);
1025 extern int vfs_test_lock(struct file *, struct file_lock *);
1026 extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
1027 extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
1028 extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
1029 extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
1030 extern void lease_get_mtime(struct inode *, struct timespec *time);
1031 extern int generic_setlease(struct file *, long, struct file_lock **);
1032 extern int vfs_setlease(struct file *, long, struct file_lock **);
1033 extern int lease_modify(struct file_lock **, int);
1034 extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
1035 extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
1036 #else /* !CONFIG_FILE_LOCKING */
1037 static inline int fcntl_getlk(struct file *file, struct flock __user *user)
1038 {
1039         return -EINVAL;
1040 }
1041 
1042 static inline int fcntl_setlk(unsigned int fd, struct file *file,
1043                               unsigned int cmd, struct flock __user *user)
1044 {
1045         return -EACCES;
1046 }
1047 
1048 #if BITS_PER_LONG == 32
1049 static inline int fcntl_getlk64(struct file *file, struct flock64 __user *user)
1050 {
1051         return -EINVAL;
1052 }
1053 
1054 static inline int fcntl_setlk64(unsigned int fd, struct file *file,
1055                                 unsigned int cmd, struct flock64 __user *user)
1056 {
1057         return -EACCES;
1058 }
1059 #endif
1060 static inline int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1061 {
1062         return 0;
1063 }
1064 
1065 static inline int fcntl_getlease(struct file *filp)
1066 {
1067         return 0;
1068 }
1069 
1070 static inline void locks_init_lock(struct file_lock *fl)
1071 {
1072         return;
1073 }
1074 
1075 static inline void __locks_copy_lock(struct file_lock *new, struct file_lock *fl)
1076 {
1077         return;
1078 }
1079 
1080 static inline void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
1081 {
1082         return;
1083 }
1084 
1085 static inline void locks_remove_posix(struct file *filp, fl_owner_t owner)
1086 {
1087         return;
1088 }
1089 
1090 static inline void locks_remove_flock(struct file *filp)
1091 {
1092         return;
1093 }
1094 
1095 static inline void posix_test_lock(struct file *filp, struct file_lock *fl)
1096 {
1097         return;
1098 }
1099 
1100 static inline int posix_lock_file(struct file *filp, struct file_lock *fl,
1101                                   struct file_lock *conflock)
1102 {
1103         return -ENOLCK;
1104 }
1105 
1106 static inline int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1107 {
1108         return -ENOLCK;
1109 }
1110 
1111 static inline int posix_unblock_lock(struct file_lock *waiter)
1112 {
1113         return -ENOENT;
1114 }
1115 
1116 static inline int vfs_test_lock(struct file *filp, struct file_lock *fl)
1117 {
1118         return 0;
1119 }
1120 
1121 static inline int vfs_lock_file(struct file *filp, unsigned int cmd,
1122                                 struct file_lock *fl, struct file_lock *conf)
1123 {
1124         return -ENOLCK;
1125 }
1126 
1127 static inline int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
1128 {
1129         return 0;
1130 }
1131 
1132 static inline int flock_lock_file_wait(struct file *filp,
1133                                        struct file_lock *request)
1134 {
1135         return -ENOLCK;
1136 }
1137 
1138 static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1139 {
1140         return 0;
1141 }
1142 
1143 static inline void lease_get_mtime(struct inode *inode, struct timespec *time)
1144 {
1145         return;
1146 }
1147 
1148 static inline int generic_setlease(struct file *filp, long arg,
1149                                     struct file_lock **flp)
1150 {
1151         return -EINVAL;
1152 }
1153 
1154 static inline int vfs_setlease(struct file *filp, long arg,
1155                                struct file_lock **lease)
1156 {
1157         return -EINVAL;
1158 }
1159 
1160 static inline int lease_modify(struct file_lock **before, int arg)
1161 {
1162         return -EINVAL;
1163 }
1164 
1165 static inline int lock_may_read(struct inode *inode, loff_t start,
1166                                 unsigned long len)
1167 {
1168         return 1;
1169 }
1170 
1171 static inline int lock_may_write(struct inode *inode, loff_t start,
1172                                  unsigned long len)
1173 {
1174         return 1;
1175 }
1176 #endif /* !CONFIG_FILE_LOCKING */
1177 
1178 
1179 struct fasync_struct {
1180         spinlock_t              fa_lock;
1181         int                     magic;
1182         int                     fa_fd;
1183         struct fasync_struct    *fa_next; /* singly linked list */
1184         struct file             *fa_file;
1185         struct rcu_head         fa_rcu;
1186 };
1187 
1188 #define FASYNC_MAGIC 0x4601
1189 
1190 /* SMP safe fasync helpers: */
1191 extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
1192 extern struct fasync_struct *fasync_insert_entry(int, struct file *, struct fasync_struct **, struct fasync_struct *);
1193 extern int fasync_remove_entry(struct file *, struct fasync_struct **);
1194 extern struct fasync_struct *fasync_alloc(void);
1195 extern void fasync_free(struct fasync_struct *);
1196 
1197 /* can be called from interrupts */
1198 extern void kill_fasync(struct fasync_struct **, int, int);
1199 
1200 extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
1201 extern int f_setown(struct file *filp, unsigned long arg, int force);
1202 extern void f_delown(struct file *filp);
1203 extern pid_t f_getown(struct file *filp);
1204 extern int send_sigurg(struct fown_struct *fown);
1205 
1206 struct mm_struct;
1207 
1208 /*
1209  *      Umount options
1210  */
1211 
1212 #define MNT_FORCE       0x00000001      /* Attempt to forcibily umount */
1213 #define MNT_DETACH      0x00000002      /* Just detach from the tree */
1214 #define MNT_EXPIRE      0x00000004      /* Mark for expiry */
1215 #define UMOUNT_NOFOLLOW 0x00000008      /* Don't follow symlink on umount */
1216 #define UMOUNT_UNUSED   0x80000000      /* Flag guaranteed to be unused */
1217 
1218 extern struct list_head super_blocks;
1219 extern spinlock_t sb_lock;
1220 
1221 /* Possible states of 'frozen' field */
1222 enum {
1223         SB_UNFROZEN = 0,                /* FS is unfrozen */
1224         SB_FREEZE_WRITE = 1,            /* Writes, dir ops, ioctls frozen */
1225         SB_FREEZE_PAGEFAULT = 2,        /* Page faults stopped as well */
1226         SB_FREEZE_FS = 3,               /* For internal FS use (e.g. to stop
1227                                          * internal threads if needed) */
1228         SB_FREEZE_COMPLETE = 4,         /* ->freeze_fs finished successfully */
1229 };
1230 
1231 #define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
1232 
1233 struct sb_writers {
1234         /* Counters for counting writers at each level */
1235         struct percpu_counter   counter[SB_FREEZE_LEVELS];
1236         wait_queue_head_t       wait;           /* queue for waiting for
1237                                                    writers / faults to finish */
1238         int                     frozen;         /* Is sb frozen? */
1239         wait_queue_head_t       wait_unfrozen;  /* queue for waiting for
1240                                                    sb to be thawed */
1241 #ifdef CONFIG_DEBUG_LOCK_ALLOC
1242         struct lockdep_map      lock_map[SB_FREEZE_LEVELS];
1243 #endif
1244 };
1245 
1246 struct super_block {
1247         struct list_head        s_list;         /* Keep this first */
1248         dev_t                   s_dev;          /* search index; _not_ kdev_t */
1249         unsigned char           s_blocksize_bits;
1250         unsigned long           s_blocksize;
1251         loff_t                  s_maxbytes;     /* Max file size */
1252         struct file_system_type *s_type;
1253         const struct super_operations   *s_op;
1254         const struct dquot_operations   *dq_op;
1255         const struct quotactl_ops       *s_qcop;
1256         const struct export_operations *s_export_op;
1257         unsigned long           s_flags;
1258         unsigned long           s_magic;
1259         struct dentry           *s_root;
1260         struct rw_semaphore     s_umount;
1261         int                     s_count;
1262         atomic_t                s_active;
1263 #ifdef CONFIG_SECURITY
1264         void                    *s_security;
1265 #endif
1266         const struct xattr_handler **s_xattr;
1267 
1268         struct list_head        s_inodes;       /* all inodes */
1269         struct hlist_bl_head    s_anon;         /* anonymous dentries for (nfs) exporting */
1270         struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
1271         struct block_device     *s_bdev;
1272         struct backing_dev_info *s_bdi;
1273         struct mtd_info         *s_mtd;
1274         struct hlist_node       s_instances;
1275         struct quota_info       s_dquot;        /* Diskquota specific options */
1276 
1277         struct sb_writers       s_writers;
1278 
1279         char s_id[32];                          /* Informational name */
1280         u8 s_uuid[16];                          /* UUID */
1281 
1282         void                    *s_fs_info;     /* Filesystem private info */
1283         unsigned int            s_max_links;
1284         fmode_t                 s_mode;
1285 
1286         /* Granularity of c/m/atime in ns.
1287            Cannot be worse than a second */
1288         u32                s_time_gran;
1289 
1290         /*
1291          * The next field is for VFS *only*. No filesystems have any business
1292          * even looking at it. You had been warned.
1293          */
1294         struct mutex s_vfs_rename_mutex;        /* Kludge */
1295 
1296         /*
1297          * Filesystem subtype.  If non-empty the filesystem type field
1298          * in /proc/mounts will be "type.subtype"
1299          */
1300         char *s_subtype;
1301 
1302         /*
1303          * Saved mount options for lazy filesystems using
1304          * generic_show_options()
1305          */
1306         char __rcu *s_options;
1307         const struct dentry_operations *s_d_op; /* default d_op for dentries */
1308 
1309         /*
1310          * Saved pool identifier for cleancache (-1 means none)
1311          */
1312         int cleancache_poolid;
1313 
1314         struct shrinker s_shrink;       /* per-sb shrinker handle */
1315 
1316         /* Number of inodes with nlink == 0 but still referenced */
1317         atomic_long_t s_remove_count;
1318 
1319         /* Being remounted read-only */
1320         int s_readonly_remount;
1321 
1322         /* AIO completions deferred from interrupt context */
1323         struct workqueue_struct *s_dio_done_wq;
1324 
1325         /*
1326          * Keep the lru lists last in the structure so they always sit on their
1327          * own individual cachelines.
1328          */
1329         struct list_lru         s_dentry_lru ____cacheline_aligned_in_smp;
1330         struct list_lru         s_inode_lru ____cacheline_aligned_in_smp;
1331         struct rcu_head         rcu;
1332 };
1333 
1334 extern struct timespec current_fs_time(struct super_block *sb);
1335 
1336 /*
1337  * Snapshotting support.
1338  */
1339 
1340 void __sb_end_write(struct super_block *sb, int level);
1341 int __sb_start_write(struct super_block *sb, int level, bool wait);
1342 
1343 /**
1344  * sb_end_write - drop write access to a superblock
1345  * @sb: the super we wrote to
1346  *
1347  * Decrement number of writers to the filesystem. Wake up possible waiters
1348  * wanting to freeze the filesystem.
1349  */
1350 static inline void sb_end_write(struct super_block *sb)
1351 {
1352         __sb_end_write(sb, SB_FREEZE_WRITE);
1353 }
1354 
1355 /**
1356  * sb_end_pagefault - drop write access to a superblock from a page fault
1357  * @sb: the super we wrote to
1358  *
1359  * Decrement number of processes handling write page fault to the filesystem.
1360  * Wake up possible waiters wanting to freeze the filesystem.
1361  */
1362 static inline void sb_end_pagefault(struct super_block *sb)
1363 {
1364         __sb_end_write(sb, SB_FREEZE_PAGEFAULT);
1365 }
1366 
1367 /**
1368  * sb_end_intwrite - drop write access to a superblock for internal fs purposes
1369  * @sb: the super we wrote to
1370  *
1371  * Decrement fs-internal number of writers to the filesystem.  Wake up possible
1372  * waiters wanting to freeze the filesystem.
1373  */
1374 static inline void sb_end_intwrite(struct super_block *sb)
1375 {
1376         __sb_end_write(sb, SB_FREEZE_FS);
1377 }
1378 
1379 /**
1380  * sb_start_write - get write access to a superblock
1381  * @sb: the super we write to
1382  *
1383  * When a process wants to write data or metadata to a file system (i.e. dirty
1384  * a page or an inode), it should embed the operation in a sb_start_write() -
1385  * sb_end_write() pair to get exclusion against file system freezing. This
1386  * function increments number of writers preventing freezing. If the file
1387  * system is already frozen, the function waits until the file system is
1388  * thawed.
1389  *
1390  * Since freeze protection behaves as a lock, users have to preserve
1391  * ordering of freeze protection and other filesystem locks. Generally,
1392  * freeze protection should be the outermost lock. In particular, we have:
1393  *
1394  * sb_start_write
1395  *   -> i_mutex                 (write path, truncate, directory ops, ...)
1396  *   -> s_umount                (freeze_super, thaw_super)
1397  */
1398 static inline void sb_start_write(struct super_block *sb)
1399 {
1400         __sb_start_write(sb, SB_FREEZE_WRITE, true);
1401 }
1402 
1403 static inline int sb_start_write_trylock(struct super_block *sb)
1404 {
1405         return __sb_start_write(sb, SB_FREEZE_WRITE, false);
1406 }
1407 
1408 /**
1409  * sb_start_pagefault - get write access to a superblock from a page fault
1410  * @sb: the super we write to
1411  *
1412  * When a process starts handling write page fault, it should embed the
1413  * operation into sb_start_pagefault() - sb_end_pagefault() pair to get
1414  * exclusion against file system freezing. This is needed since the page fault
1415  * is going to dirty a page. This function increments number of running page
1416  * faults preventing freezing. If the file system is already frozen, the
1417  * function waits until the file system is thawed.
1418  *
1419  * Since page fault freeze protection behaves as a lock, users have to preserve
1420  * ordering of freeze protection and other filesystem locks. It is advised to
1421  * put sb_start_pagefault() close to mmap_sem in lock ordering. Page fault
1422  * handling code implies lock dependency:
1423  *
1424  * mmap_sem
1425  *   -> sb_start_pagefault
1426  */
1427 static inline void sb_start_pagefault(struct super_block *sb)
1428 {
1429         __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
1430 }
1431 
1432 /*
1433  * sb_start_intwrite - get write access to a superblock for internal fs purposes
1434  * @sb: the super we write to
1435  *
1436  * This is the third level of protection against filesystem freezing. It is
1437  * free for use by a filesystem. The only requirement is that it must rank
1438  * below sb_start_pagefault.
1439  *
1440  * For example filesystem can call sb_start_intwrite() when starting a
1441  * transaction which somewhat eases handling of freezing for internal sources
1442  * of filesystem changes (internal fs threads, discarding preallocation on file
1443  * close, etc.).
1444  */
1445 static inline void sb_start_intwrite(struct super_block *sb)
1446 {
1447         __sb_start_write(sb, SB_FREEZE_FS, true);
1448 }
1449 
1450 
1451 extern bool inode_owner_or_capable(const struct inode *inode);
1452 
1453 /*
1454  * VFS helper functions..
1455  */
1456 extern int vfs_create(struct inode *, struct dentry *, umode_t, bool);
1457 extern int vfs_mkdir(struct inode *, struct dentry *, umode_t);
1458 extern int vfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
1459 extern int vfs_symlink(struct inode *, struct dentry *, const char *);
1460 extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
1461 extern int vfs_rmdir(struct inode *, struct dentry *);
1462 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
1463 extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **);
1464 
1465 /*
1466  * VFS dentry helper functions.
1467  */
1468 extern void dentry_unhash(struct dentry *dentry);
1469 
1470 /*
1471  * VFS file helper functions.
1472  */
1473 extern void inode_init_owner(struct inode *inode, const struct inode *dir,
1474                         umode_t mode);
1475 /*
1476  * VFS FS_IOC_FIEMAP helper definitions.
1477  */
1478 struct fiemap_extent_info {
1479         unsigned int fi_flags;          /* Flags as passed from user */
1480         unsigned int fi_extents_mapped; /* Number of mapped extents */
1481         unsigned int fi_extents_max;    /* Size of fiemap_extent array */
1482         struct fiemap_extent __user *fi_extents_start; /* Start of
1483                                                         fiemap_extent array */
1484 };
1485 int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
1486                             u64 phys, u64 len, u32 flags);
1487 int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
1488 
1489 /*
1490  * File types
1491  *
1492  * NOTE! These match bits 12..15 of stat.st_mode
1493  * (ie "(i_mode >> 12) & 15").
1494  */
1495 #define DT_UNKNOWN      0
1496 #define DT_FIFO         1
1497 #define DT_CHR          2
1498 #define DT_DIR          4
1499 #define DT_BLK          6
1500 #define DT_REG          8
1501 #define DT_LNK          10
1502 #define DT_SOCK         12
1503 #define DT_WHT          14
1504 
1505 /*
1506  * This is the "filldir" function type, used by readdir() to let
1507  * the kernel specify what kind of dirent layout it wants to have.
1508  * This allows the kernel to read directories into kernel space or
1509  * to have different dirent layouts depending on the binary type.
1510  */
1511 typedef int (*filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
1512 struct dir_context {
1513         const filldir_t actor;
1514         loff_t pos;
1515 };
1516 
1517 struct block_device_operations;
1518 
1519 /* These macros are for out of kernel modules to test that
1520  * the kernel supports the unlocked_ioctl and compat_ioctl
1521  * fields in struct file_operations. */
1522 #define HAVE_COMPAT_IOCTL 1
1523 #define HAVE_UNLOCKED_IOCTL 1
1524 
1525 struct file_operations {
1526         struct module *owner;
1527         loff_t (*llseek) (struct file *, loff_t, int);
1528         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
1529         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
1530         ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
1531         ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
1532         int (*iterate) (struct file *, struct dir_context *);
1533         unsigned int (*poll) (struct file *, struct poll_table_struct *);
1534         long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
1535         long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
1536         int (*mmap) (struct file *, struct vm_area_struct *);
1537         int (*open) (struct inode *, struct file *);
1538         int (*flush) (struct file *, fl_owner_t id);
1539         int (*release) (struct inode *, struct file *);
1540         int (*fsync) (struct file *, loff_t, loff_t, int datasync);
1541         int (*aio_fsync) (struct kiocb *, int datasync);
1542         int (*fasync) (int, struct file *, int);
1543         int (*lock) (struct file *, int, struct file_lock *);
1544         ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
1545         unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1546         int (*check_flags)(int);
1547         int (*flock) (struct file *, int, struct file_lock *);
1548         ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
1549         ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
1550         int (*setlease)(struct file *, long, struct file_lock **);
1551         long (*fallocate)(struct file *file, int mode, loff_t offset,
1552                           loff_t len);
1553         int (*show_fdinfo)(struct seq_file *m, struct file *f);
1554 };
1555 
1556 struct inode_operations {
1557         struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
1558         void * (*follow_link) (struct dentry *, struct nameidata *);
1559         int (*permission) (struct inode *, int);
1560         struct posix_acl * (*get_acl)(struct inode *, int);
1561 
1562         int (*readlink) (struct dentry *, char __user *,int);
1563         void (*put_link) (struct dentry *, struct nameidata *, void *);
1564 
1565         int (*create) (struct inode *,struct dentry *, umode_t, bool);
1566         int (*link) (struct dentry *,struct inode *,struct dentry *);
1567         int (*unlink) (struct inode *,struct dentry *);
1568         int (*symlink) (struct inode *,struct dentry *,const char *);
1569         int (*mkdir) (struct inode *,struct dentry *,umode_t);
1570         int (*rmdir) (struct inode *,struct dentry *);
1571         int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
1572         int (*rename) (struct inode *, struct dentry *,
1573                         struct inode *, struct dentry *);
1574         int (*setattr) (struct dentry *, struct iattr *);
1575         int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
1576         int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
1577         ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
1578         ssize_t (*listxattr) (struct dentry *, char *, size_t);
1579         int (*removexattr) (struct dentry *, const char *);
1580         int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
1581                       u64 len);
1582         int (*update_time)(struct inode *, struct timespec *, int);
1583         int (*atomic_open)(struct inode *, struct dentry *,
1584                            struct file *, unsigned open_flag,
1585                            umode_t create_mode, int *opened);
1586         int (*tmpfile) (struct inode *, struct dentry *, umode_t);
1587         int (*set_acl)(struct inode *, struct posix_acl *, int);
1588 } ____cacheline_aligned;
1589 
1590 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
1591                               unsigned long nr_segs, unsigned long fast_segs,
1592                               struct iovec *fast_pointer,
1593                               struct iovec **ret_pointer);
1594 
1595 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
1596 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
1597 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
1598                 unsigned long, loff_t *);
1599 extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
1600                 unsigned long, loff_t *);
1601 
1602 struct super_operations {
1603         struct inode *(*alloc_inode)(struct super_block *sb);
1604         void (*destroy_inode)(struct inode *);
1605 
1606         void (*dirty_inode) (struct inode *, int flags);
1607         int (*write_inode) (struct inode *, struct writeback_control *wbc);
1608         int (*drop_inode) (struct inode *);
1609         void (*evict_inode) (struct inode *);
1610         void (*put_super) (struct super_block *);
1611         int (*sync_fs)(struct super_block *sb, int wait);
1612         int (*freeze_fs) (struct super_block *);
1613         int (*unfreeze_fs) (struct super_block *);
1614         int (*statfs) (struct dentry *, struct kstatfs *);
1615         int (*remount_fs) (struct super_block *, int *, char *);
1616         void (*umount_begin) (struct super_block *);
1617 
1618         int (*show_options)(struct seq_file *, struct dentry *);
1619         int (*show_devname)(struct seq_file *, struct dentry *);
1620         int (*show_path)(struct seq_file *, struct dentry *);
1621         int (*show_stats)(struct seq_file *, struct dentry *);
1622 #ifdef CONFIG_QUOTA
1623         ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
1624         ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
1625 #endif
1626         int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
1627         long (*nr_cached_objects)(struct super_block *, int);
1628         long (*free_cached_objects)(struct super_block *, long, int);
1629 };
1630 
1631 /*
1632  * Inode flags - they have no relation to superblock flags now
1633  */
1634 #define S_SYNC          1       /* Writes are synced at once */
1635 #define S_NOATIME       2       /* Do not update access times */
1636 #define S_APPEND        4       /* Append-only file */
1637 #define S_IMMUTABLE     8       /* Immutable file */
1638 #define S_DEAD          16      /* removed, but still open directory */
1639 #define S_NOQUOTA       32      /* Inode is not counted to quota */
1640 #define S_DIRSYNC       64      /* Directory modifications are synchronous */
1641 #define S_NOCMTIME      128     /* Do not update file c/mtime */
1642 #define S_SWAPFILE      256     /* Do not truncate: swapon got its bmaps */
1643 #define S_PRIVATE       512     /* Inode is fs-internal */
1644 #define S_IMA           1024    /* Inode has an associated IMA struct */
1645 #define S_AUTOMOUNT     2048    /* Automount/referral quasi-directory */
1646 #define S_NOSEC         4096    /* no suid or xattr security attributes */
1647 
1648 /*
1649  * Note that nosuid etc flags are inode-specific: setting some file-system
1650  * flags just means all the inodes inherit those flags by default. It might be
1651  * possible to override it selectively if you really wanted to with some
1652  * ioctl() that is not currently implemented.
1653  *
1654  * Exception: MS_RDONLY is always applied to the entire file system.
1655  *
1656  * Unfortunately, it is possible to change a filesystems flags with it mounted
1657  * with files in use.  This means that all of the inodes will not have their
1658  * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
1659  * flags, so these have to be checked separately. -- rmk@arm.uk.linux.org
1660  */
1661 #define __IS_FLG(inode, flg)    ((inode)->i_sb->s_flags & (flg))
1662 
1663 #define IS_RDONLY(inode)        ((inode)->i_sb->s_flags & MS_RDONLY)
1664 #define IS_SYNC(inode)          (__IS_FLG(inode, MS_SYNCHRONOUS) || \
1665                                         ((inode)->i_flags & S_SYNC))
1666 #define IS_DIRSYNC(inode)       (__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
1667                                         ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
1668 #define IS_MANDLOCK(inode)      __IS_FLG(inode, MS_MANDLOCK)
1669 #define IS_NOATIME(inode)       __IS_FLG(inode, MS_RDONLY|MS_NOATIME)
1670 #define IS_I_VERSION(inode)     __IS_FLG(inode, MS_I_VERSION)
1671 
1672 #define IS_NOQUOTA(inode)       ((inode)->i_flags & S_NOQUOTA)
1673 #define IS_APPEND(inode)        ((inode)->i_flags & S_APPEND)
1674 #define IS_IMMUTABLE(inode)     ((inode)->i_flags & S_IMMUTABLE)
1675 #define IS_POSIXACL(inode)      __IS_FLG(inode, MS_POSIXACL)
1676 
1677 #define IS_DEADDIR(inode)       ((inode)->i_flags & S_DEAD)
1678 #define IS_NOCMTIME(inode)      ((inode)->i_flags & S_NOCMTIME)
1679 #define IS_SWAPFILE(inode)      ((inode)->i_flags & S_SWAPFILE)
1680 #define IS_PRIVATE(inode)       ((inode)->i_flags & S_PRIVATE)
1681 #define IS_IMA(inode)           ((inode)->i_flags & S_IMA)
1682 #define IS_AUTOMOUNT(inode)     ((inode)->i_flags & S_AUTOMOUNT)
1683 #define IS_NOSEC(inode)         ((inode)->i_flags & S_NOSEC)
1684 
1685 /*
1686  * Inode state bits.  Protected by inode->i_lock
1687  *
1688  * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
1689  * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
1690  *
1691  * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
1692  * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
1693  * various stages of removing an inode.
1694  *
1695  * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
1696  *
1697  * I_DIRTY_SYNC         Inode is dirty, but doesn't have to be written on
1698  *                      fdatasync().  i_atime is the usual cause.
1699  * I_DIRTY_DATASYNC     Data-related inode changes pending. We keep track of
1700  *                      these changes separately from I_DIRTY_SYNC so that we
1701  *                      don't have to write inode on fdatasync() when only
1702  *                      mtime has changed in it.
1703  * I_DIRTY_PAGES        Inode has dirty pages.  Inode itself may be clean.
1704  * I_NEW                Serves as both a mutex and completion notification.
1705  *                      New inodes set I_NEW.  If two processes both create
1706  *                      the same inode, one of them will release its inode and
1707  *                      wait for I_NEW to be released before returning.
1708  *                      Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
1709  *                      also cause waiting on I_NEW, without I_NEW actually
1710  *                      being set.  find_inode() uses this to prevent returning
1711  *                      nearly-dead inodes.
1712  * I_WILL_FREE          Must be set when calling write_inode_now() if i_count
1713  *                      is zero.  I_FREEING must be set when I_WILL_FREE is
1714  *                      cleared.
1715  * I_FREEING            Set when inode is about to be freed but still has dirty
1716  *                      pages or buffers attached or the inode itself is still
1717  *                      dirty.
1718  * I_CLEAR              Added by clear_inode().  In this state the inode is
1719  *                      clean and can be destroyed.  Inode keeps I_FREEING.
1720  *
1721  *                      Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
1722  *                      prohibited for many purposes.  iget() must wait for
1723  *                      the inode to be completely released, then create it
1724  *                      anew.  Other functions will just ignore such inodes,
1725  *                      if appropriate.  I_NEW is used for waiting.
1726  *
1727  * I_SYNC               Writeback of inode is running. The bit is set during
1728  *                      data writeback, and cleared with a wakeup on the bit
1729  *                      address once it is done. The bit is also used to pin
1730  *                      the inode in memory for flusher thread.
1731  *
1732  * I_REFERENCED         Marks the inode as recently references on the LRU list.
1733  *
1734  * I_DIO_WAKEUP         Never set.  Only used as a key for wait_on_bit().
1735  *
1736  * Q: What is the difference between I_WILL_FREE and I_FREEING?
1737  */
1738 #define I_DIRTY_SYNC            (1 << 0)
1739 #define I_DIRTY_DATASYNC        (1 << 1)
1740 #define I_DIRTY_PAGES           (1 << 2)
1741 #define __I_NEW                 3
1742 #define I_NEW                   (1 << __I_NEW)
1743 #define I_WILL_FREE             (1 << 4)
1744 #define I_FREEING               (1 << 5)
1745 #define I_CLEAR                 (1 << 6)
1746 #define __I_SYNC                7
1747 #define I_SYNC                  (1 << __I_SYNC)
1748 #define I_REFERENCED            (1 << 8)
1749 #define __I_DIO_WAKEUP          9
1750 #define I_DIO_WAKEUP            (1 << I_DIO_WAKEUP)
1751 #define I_LINKABLE              (1 << 10)
1752 
1753 #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)
1754 
1755 extern void __mark_inode_dirty(struct inode *, int);
1756 static inline void mark_inode_dirty(struct inode *inode)
1757 {
1758         __mark_inode_dirty(inode, I_DIRTY);
1759 }
1760 
1761 static inline void mark_inode_dirty_sync(struct inode *inode)
1762 {
1763         __mark_inode_dirty(inode, I_DIRTY_SYNC);
1764 }
1765 
1766 extern void inc_nlink(struct inode *inode);
1767 extern void drop_nlink(struct inode *inode);
1768 extern void clear_nlink(struct inode *inode);
1769 extern void set_nlink(struct inode *inode, unsigned int nlink);
1770 
1771 static inline void inode_inc_link_count(struct inode *inode)
1772 {
1773         inc_nlink(inode);
1774         mark_inode_dirty(inode);
1775 }
1776 
1777 static inline void inode_dec_link_count(struct inode *inode)
1778 {
1779         drop_nlink(inode);
1780         mark_inode_dirty(inode);
1781 }
1782 
1783 /**
1784  * inode_inc_iversion - increments i_version
1785  * @inode: inode that need to be updated
1786  *
1787  * Every time the inode is modified, the i_version field will be incremented.
1788  * The filesystem has to be mounted with i_version flag
1789  */
1790 
1791 static inline void inode_inc_iversion(struct inode *inode)
1792 {
1793        spin_lock(&inode->i_lock);
1794        inode->i_version++;
1795        spin_unlock(&inode->i_lock);
1796 }
1797 
1798 enum file_time_flags {
1799         S_ATIME = 1,
1800         S_MTIME = 2,
1801         S_CTIME = 4,
1802         S_VERSION = 8,
1803 };
1804 
1805 extern void touch_atime(const struct path *);
1806 static inline void file_accessed(struct file *file)
1807 {
1808         if (!(file->f_flags & O_NOATIME))
1809                 touch_atime(&file->f_path);
1810 }
1811 
1812 int sync_inode(struct inode *inode, struct writeback_control *wbc);
1813 int sync_inode_metadata(struct inode *inode, int wait);
1814 
1815 struct file_system_type {
1816         const char *name;
1817         int fs_flags;
1818 #define FS_REQUIRES_DEV         1 
1819 #define FS_BINARY_MOUNTDATA     2
1820 #define FS_HAS_SUBTYPE          4
1821 #define FS_USERNS_MOUNT         8       /* Can be mounted by userns root */
1822 #define FS_USERNS_DEV_MOUNT     16 /* A userns mount does not imply MNT_NODEV */
1823 #define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
1824         struct dentry *(*mount) (struct file_system_type *, int,
1825                        const char *, void *);
1826         void (*kill_sb) (struct super_block *);
1827         struct module *owner;
1828         struct file_system_type * next;
1829         struct hlist_head fs_supers;
1830 
1831         struct lock_class_key s_lock_key;
1832         struct lock_class_key s_umount_key;
1833         struct lock_class_key s_vfs_rename_key;
1834         struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];
1835 
1836         struct lock_class_key i_lock_key;
1837         struct lock_class_key i_mutex_key;
1838         struct lock_class_key i_mutex_dir_key;
1839 };
1840 
1841 #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)
1842 
1843 extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
1844         void *data, int (*fill_super)(struct super_block *, void *, int));
1845 extern struct dentry *mount_bdev(struct file_system_type *fs_type,
1846         int flags, const char *dev_name, void *data,
1847         int (*fill_super)(struct super_block *, void *, int));
1848 extern struct dentry *mount_single(struct file_system_type *fs_type,
1849         int flags, void *data,
1850         int (*fill_super)(struct super_block *, void *, int));
1851 extern struct dentry *mount_nodev(struct file_system_type *fs_type,
1852         int flags, void *data,
1853         int (*fill_super)(struct super_block *, void *, int));
1854 extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
1855 void generic_shutdown_super(struct super_block *sb);
1856 void kill_block_super(struct super_block *sb);
1857 void kill_anon_super(struct super_block *sb);
1858 void kill_litter_super(struct super_block *sb);
1859 void deactivate_super(struct super_block *sb);
1860 void deactivate_locked_super(struct super_block *sb);
1861 int set_anon_super(struct super_block *s, void *data);
1862 int get_anon_bdev(dev_t *);
1863 void free_anon_bdev(dev_t);
1864 struct super_block *sget(struct file_system_type *type,
1865                         int (*test)(struct super_block *,void *),
1866                         int (*set)(struct super_block *,void *),
1867                         int flags, void *data);
1868 extern struct dentry *mount_pseudo(struct file_system_type *, char *,
1869         const struct super_operations *ops,
1870         const struct dentry_operations *dops,
1871         unsigned long);
1872 
1873 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
1874 #define fops_get(fops) \
1875         (((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
1876 #define fops_put(fops) \
1877         do { if (fops) module_put((fops)->owner); } while(0)
1878 /*
1879  * This one is to be used *ONLY* from ->open() instances.
1880  * fops must be non-NULL, pinned down *and* module dependencies
1881  * should be sufficient to pin the caller down as well.
1882  */
1883 #define replace_fops(f, fops) \
1884         do {    \
1885                 struct file *__file = (f); \
1886                 fops_put(__file->f_op); \
1887                 BUG_ON(!(__file->f_op = (fops))); \
1888         } while(0)
1889 
1890 extern int register_filesystem(struct file_system_type *);
1891 extern int unregister_filesystem(struct file_system_type *);
1892 extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
1893 #define kern_mount(type) kern_mount_data(type, NULL)
1894 extern void kern_unmount(struct vfsmount *mnt);
1895 extern int may_umount_tree(struct vfsmount *);
1896 extern int may_umount(struct vfsmount *);
1897 extern long do_mount(const char *, const char *, const char *, unsigned long, void *);
1898 extern struct vfsmount *collect_mounts(struct path *);
1899 extern void drop_collected_mounts(struct vfsmount *);
1900 extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
1901                           struct vfsmount *);
1902 extern int vfs_statfs(struct path *, struct kstatfs *);
1903 extern int user_statfs(const char __user *, struct kstatfs *);
1904 extern int fd_statfs(int, struct kstatfs *);
1905 extern int vfs_ustat(dev_t, struct kstatfs *);
1906 extern int freeze_super(struct super_block *super);
1907 extern int thaw_super(struct super_block *super);
1908 extern bool our_mnt(struct vfsmount *mnt);
1909 extern bool fs_fully_visible(struct file_system_type *);
1910 
1911 extern int current_umask(void);
1912 
1913 extern void ihold(struct inode * inode);
1914 extern void iput(struct inode *);
1915 
1916 /* /sys/fs */
1917 extern struct kobject *fs_kobj;
1918 
1919 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
1920 
1921 #define FLOCK_VERIFY_READ  1
1922 #define FLOCK_VERIFY_WRITE 2
1923 
1924 #ifdef CONFIG_FILE_LOCKING
1925 extern int locks_mandatory_locked(struct inode *);
1926 extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);
1927 
1928 /*
1929  * Candidates for mandatory locking have the setgid bit set
1930  * but no group execute bit -  an otherwise meaningless combination.
1931  */
1932 
1933 static inline int __mandatory_lock(struct inode *ino)
1934 {
1935         return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
1936 }
1937 
1938 /*
1939  * ... and these candidates should be on MS_MANDLOCK mounted fs,
1940  * otherwise these will be advisory locks
1941  */
1942 
1943 static inline int mandatory_lock(struct inode *ino)
1944 {
1945         return IS_MANDLOCK(ino) && __mandatory_lock(ino);
1946 }
1947 
1948 static inline int locks_verify_locked(struct inode *inode)
1949 {
1950         if (mandatory_lock(inode))
1951                 return locks_mandatory_locked(inode);
1952         return 0;
1953 }
1954 
1955 static inline int locks_verify_truncate(struct inode *inode,
1956                                     struct file *filp,
1957                                     loff_t size)
1958 {
1959         if (inode->i_flock && mandatory_lock(inode))
1960                 return locks_mandatory_area(
1961                         FLOCK_VERIFY_WRITE, inode, filp,
1962                         size < inode->i_size ? size : inode->i_size,
1963                         (size < inode->i_size ? inode->i_size - size
1964                          : size - inode->i_size)
1965                 );
1966         return 0;
1967 }
1968 
1969 static inline int break_lease(struct inode *inode, unsigned int mode)
1970 {
1971         if (inode->i_flock)
1972                 return __break_lease(inode, mode, FL_LEASE);
1973         return 0;
1974 }
1975 
1976 static inline int break_deleg(struct inode *inode, unsigned int mode)
1977 {
1978         if (inode->i_flock)
1979                 return __break_lease(inode, mode, FL_DELEG);
1980         return 0;
1981 }
1982 
1983 static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
1984 {
1985         int ret;
1986 
1987         ret = break_deleg(inode, O_WRONLY|O_NONBLOCK);
1988         if (ret == -EWOULDBLOCK && delegated_inode) {
1989                 *delegated_inode = inode;
1990                 ihold(inode);
1991         }
1992         return ret;
1993 }
1994 
1995 static inline int break_deleg_wait(struct inode **delegated_inode)
1996 {
1997         int ret;
1998 
1999         ret = break_deleg(*delegated_inode, O_WRONLY);
2000         iput(*delegated_inode);
2001         *delegated_inode = NULL;
2002         return ret;
2003 }
2004 
2005 #else /* !CONFIG_FILE_LOCKING */
2006 static inline int locks_mandatory_locked(struct inode *inode)
2007 {
2008         return 0;
2009 }
2010 
2011 static inline int locks_mandatory_area(int rw, struct inode *inode,
2012                                        struct file *filp, loff_t offset,
2013                                        size_t count)
2014 {
2015         return 0;
2016 }
2017 
2018 static inline int __mandatory_lock(struct inode *inode)
2019 {
2020         return 0;
2021 }
2022 
2023 static inline int mandatory_lock(struct inode *inode)
2024 {
2025         return 0;
2026 }
2027 
2028 static inline int locks_verify_locked(struct inode *inode)
2029 {
2030         return 0;
2031 }
2032 
2033 static inline int locks_verify_truncate(struct inode *inode, struct file *filp,
2034                                         size_t size)
2035 {
2036         return 0;
2037 }
2038 
2039 static inline int break_lease(struct inode *inode, unsigned int mode)
2040 {
2041         return 0;
2042 }
2043 
2044 static inline int break_deleg(struct inode *inode, unsigned int mode)
2045 {
2046         return 0;
2047 }
2048 
2049 static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
2050 {
2051         return 0;
2052 }
2053 
2054 static inline int break_deleg_wait(struct inode **delegated_inode)
2055 {
2056         BUG();
2057         return 0;
2058 }
2059 
2060 #endif /* CONFIG_FILE_LOCKING */
2061 
2062 /* fs/open.c */
2063 struct audit_names;
2064 struct filename {
2065         const char              *name;  /* pointer to actual string */
2066         const __user char       *uptr;  /* original userland pointer */
2067         struct audit_names      *aname;
2068         bool                    separate; /* should "name" be freed? */
2069 };
2070 
2071 extern long vfs_truncate(struct path *, loff_t);
2072 extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
2073                        struct file *filp);
2074 extern int do_fallocate(struct file *file, int mode, loff_t offset,
2075                         loff_t len);
2076 extern long do_sys_open(int dfd, const char __user *filename, int flags,
2077                         umode_t mode);
2078 extern struct file *file_open_name(struct filename *, int, umode_t);
2079 extern struct file *filp_open(const char *, int, umode_t);
2080 extern struct file *file_open_root(struct dentry *, struct vfsmount *,
2081                                    const char *, int);
2082 extern struct file * dentry_open(const struct path *, int, const struct cred *);
2083 extern int filp_close(struct file *, fl_owner_t id);
2084 
2085 extern struct filename *getname(const char __user *);
2086 extern struct filename *getname_kernel(const char *);
2087 
2088 enum {
2089         FILE_CREATED = 1,
2090         FILE_OPENED = 2
2091 };
2092 extern int finish_open(struct file *file, struct dentry *dentry,
2093                         int (*open)(struct inode *, struct file *),
2094                         int *opened);
2095 extern int finish_no_open(struct file *file, struct dentry *dentry);
2096 
2097 /* fs/ioctl.c */
2098 
2099 extern int ioctl_preallocate(struct file *filp, void __user *argp);
2100 
2101 /* fs/dcache.c */
2102 extern void __init vfs_caches_init_early(void);
2103 extern void __init vfs_caches_init(unsigned long);
2104 
2105 extern struct kmem_cache *names_cachep;
2106 
2107 extern void final_putname(struct filename *name);
2108 
2109 #define __getname()             kmem_cache_alloc(names_cachep, GFP_KERNEL)
2110 #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
2111 #ifndef CONFIG_AUDITSYSCALL
2112 #define putname(name)           final_putname(name)
2113 #else
2114 extern void putname(struct filename *name);
2115 #endif
2116 
2117 #ifdef CONFIG_BLOCK
2118 extern int register_blkdev(unsigned int, const char *);
2119 extern void unregister_blkdev(unsigned int, const char *);
2120 extern struct block_device *bdget(dev_t);
2121 extern struct block_device *bdgrab(struct block_device *bdev);
2122 extern void bd_set_size(struct block_device *, loff_t size);
2123 extern void bd_forget(struct inode *inode);
2124 extern void bdput(struct block_device *);
2125 extern void invalidate_bdev(struct block_device *);
2126 extern void iterate_bdevs(void (*)(struct block_device *, void *), void *);
2127 extern int sync_blockdev(struct block_device *bdev);
2128 extern void kill_bdev(struct block_device *);
2129 extern struct super_block *freeze_bdev(struct block_device *);
2130 extern void emergency_thaw_all(void);
2131 extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
2132 extern int fsync_bdev(struct block_device *);
2133 extern int sb_is_blkdev_sb(struct super_block *sb);
2134 #else
2135 static inline void bd_forget(struct inode *inode) {}
2136 static inline int sync_blockdev(struct block_device *bdev) { return 0; }
2137 static inline void kill_bdev(struct block_device *bdev) {}
2138 static inline void invalidate_bdev(struct block_device *bdev) {}
2139 
2140 static inline struct super_block *freeze_bdev(struct block_device *sb)
2141 {
2142         return NULL;
2143 }
2144 
2145 static inline int thaw_bdev(struct block_device *bdev, struct super_block *sb)
2146 {
2147         return 0;
2148 }
2149 
2150 static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void *arg)
2151 {
2152 }
2153 
2154 static inline int sb_is_blkdev_sb(struct super_block *sb)
2155 {
2156         return 0;
2157 }
2158 #endif
2159 extern int sync_filesystem(struct super_block *);
2160 extern const struct file_operations def_blk_fops;
2161 extern const struct file_operations def_chr_fops;
2162 extern const struct file_operations bad_sock_fops;
2163 #ifdef CONFIG_BLOCK
2164 extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
2165 extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
2166 extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
2167 extern int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder);
2168 extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
2169                                                void *holder);
2170 extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
2171                                               void *holder);
2172 extern void blkdev_put(struct block_device *bdev, fmode_t mode);
2173 #ifdef CONFIG_SYSFS
2174 extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
2175 extern void bd_unlink_disk_holder(struct block_device *bdev,
2176                                   struct gendisk *disk);
2177 #else
2178 static inline int bd_link_disk_holder(struct block_device *bdev,
2179                                       struct gendisk *disk)
2180 {
2181         return 0;
2182 }
2183 static inline void bd_unlink_disk_holder(struct block_device *bdev,
2184                                          struct gendisk *disk)
2185 {
2186 }
2187 #endif
2188 #endif
2189 
2190 /* fs/char_dev.c */
2191 #define CHRDEV_MAJOR_HASH_SIZE  255
2192 extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
2193 extern int register_chrdev_region(dev_t, unsigned, const char *);
2194 extern int __register_chrdev(unsigned int major, unsigned int baseminor,
2195                              unsigned int count, const char *name,
2196                              const struct file_operations *fops);
2197 extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
2198                                 unsigned int count, const char *name);
2199 extern void unregister_chrdev_region(dev_t, unsigned);
2200 extern void chrdev_show(struct seq_file *,off_t);
2201 
2202 static inline int register_chrdev(unsigned int major, const char *name,
2203                                   const struct file_operations *fops)
2204 {
2205         return __register_chrdev(major, 0, 256, name, fops);
2206 }
2207 
2208 static inline void unregister_chrdev(unsigned int major, const char *name)
2209 {
2210         __unregister_chrdev(major, 0, 256, name);
2211 }
2212 
2213 /* fs/block_dev.c */
2214 #define BDEVNAME_SIZE   32      /* Largest string for a blockdev identifier */
2215 #define BDEVT_SIZE      10      /* Largest string for MAJ:MIN for blkdev */
2216 
2217 #ifdef CONFIG_BLOCK
2218 #define BLKDEV_MAJOR_HASH_SIZE  255
2219 extern const char *__bdevname(dev_t, char *buffer);
2220 extern const char *bdevname(struct block_device *bdev, char *buffer);
2221 extern struct block_device *lookup_bdev(const char *);
2222 extern void blkdev_show(struct seq_file *,off_t);
2223 
2224 #else
2225 #define BLKDEV_MAJOR_HASH_SIZE  0
2226 #endif
2227 
2228 extern void init_special_inode(struct inode *, umode_t, dev_t);
2229 
2230 /* Invalid inode operations -- fs/bad_inode.c */
2231 extern void make_bad_inode(struct inode *);
2232 extern int is_bad_inode(struct inode *);
2233 
2234 #ifdef CONFIG_BLOCK
2235 /*
2236  * return READ, READA, or WRITE
2237  */
2238 #define bio_rw(bio)             ((bio)->bi_rw & (RW_MASK | RWA_MASK))
2239 
2240 /*
2241  * return data direction, READ or WRITE
2242  */
2243 #define bio_data_dir(bio)       ((bio)->bi_rw & 1)
2244 
2245 extern void check_disk_size_change(struct gendisk *disk,
2246                                    struct block_device *bdev);
2247 extern int revalidate_disk(struct gendisk *);
2248 extern int check_disk_change(struct block_device *);
2249 extern int __invalidate_device(struct block_device *, bool);
2250 extern int invalidate_partition(struct gendisk *, int);
2251 #endif
2252 unsigned long invalidate_mapping_pages(struct address_space *mapping,
2253                                         pgoff_t start, pgoff_t end);
2254 
2255 static inline void invalidate_remote_inode(struct inode *inode)
2256 {
2257         if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
2258             S_ISLNK(inode->i_mode))
2259                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
2260 }
2261 extern int invalidate_inode_pages2(struct address_space *mapping);
2262 extern int invalidate_inode_pages2_range(struct address_space *mapping,
2263                                          pgoff_t start, pgoff_t end);
2264 extern int write_inode_now(struct inode *, int);
2265 extern int filemap_fdatawrite(struct address_space *);
2266 extern int filemap_flush(struct address_space *);
2267 extern int filemap_fdatawait(struct address_space *);
2268 extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
2269                                    loff_t lend);
2270 extern int filemap_write_and_wait(struct address_space *mapping);
2271 extern int filemap_write_and_wait_range(struct address_space *mapping,
2272                                         loff_t lstart, loff_t lend);
2273 extern int __filemap_fdatawrite_range(struct address_space *mapping,
2274                                 loff_t start, loff_t end, int sync_mode);
2275 extern int filemap_fdatawrite_range(struct address_space *mapping,
2276                                 loff_t start, loff_t end);
2277 
2278 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
2279                            int datasync);
2280 extern int vfs_fsync(struct file *file, int datasync);
2281 static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
2282 {
2283         if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
2284                 return 0;
2285         return vfs_fsync_range(file, pos, pos + count - 1,
2286                                (file->f_flags & __O_SYNC) ? 0 : 1);
2287 }
2288 extern void emergency_sync(void);
2289 extern void emergency_remount(void);
2290 #ifdef CONFIG_BLOCK
2291 extern sector_t bmap(struct inode *, sector_t);
2292 #endif
2293 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
2294 extern int inode_permission(struct inode *, int);
2295 extern int generic_permission(struct inode *, int);
2296 
2297 static inline bool execute_ok(struct inode *inode)
2298 {
2299         return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
2300 }
2301 
2302 static inline struct inode *file_inode(struct file *f)
2303 {
2304         return f->f_inode;
2305 }
2306 
2307 static inline void file_start_write(struct file *file)
2308 {
2309         if (!S_ISREG(file_inode(file)->i_mode))
2310                 return;
2311         __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
2312 }
2313 
2314 static inline bool file_start_write_trylock(struct file *file)
2315 {
2316         if (!S_ISREG(file_inode(file)->i_mode))
2317                 return true;
2318         return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false);
2319 }
2320 
2321 static inline void file_end_write(struct file *file)
2322 {
2323         if (!S_ISREG(file_inode(file)->i_mode))
2324                 return;
2325         __sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE);
2326 }
2327 
2328 /*
2329  * get_write_access() gets write permission for a file.
2330  * put_write_access() releases this write permission.
2331  * This is used for regular files.
2332  * We cannot support write (and maybe mmap read-write shared) accesses and
2333  * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
2334  * can have the following values:
2335  * 0: no writers, no VM_DENYWRITE mappings
2336  * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
2337  * > 0: (i_writecount) users are writing to the file.
2338  *
2339  * Normally we operate on that counter with atomic_{inc,dec} and it's safe
2340  * except for the cases where we don't hold i_writecount yet. Then we need to
2341  * use {get,deny}_write_access() - these functions check the sign and refuse
2342  * to do the change if sign is wrong.
2343  */
2344 static inline int get_write_access(struct inode *inode)
2345 {
2346         return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
2347 }
2348 static inline int deny_write_access(struct file *file)
2349 {
2350         struct inode *inode = file_inode(file);
2351         return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
2352 }
2353 static inline void put_write_access(struct inode * inode)
2354 {
2355         atomic_dec(&inode->i_writecount);
2356 }
2357 static inline void allow_write_access(struct file *file)
2358 {
2359         if (file)
2360                 atomic_inc(&file_inode(file)->i_writecount);
2361 }
2362 static inline bool inode_is_open_for_write(const struct inode *inode)
2363 {
2364         return atomic_read(&inode->i_writecount) > 0;
2365 }
2366 
2367 #ifdef CONFIG_IMA
2368 static inline void i_readcount_dec(struct inode *inode)
2369 {
2370         BUG_ON(!atomic_read(&inode->i_readcount));
2371         atomic_dec(&inode->i_readcount);
2372 }
2373 static inline void i_readcount_inc(struct inode *inode)
2374 {
2375         atomic_inc(&inode->i_readcount);
2376 }
2377 #else
2378 static inline void i_readcount_dec(struct inode *inode)
2379 {
2380         return;
2381 }
2382 static inline void i_readcount_inc(struct inode *inode)
2383 {
2384         return;
2385 }
2386 #endif
2387 extern int do_pipe_flags(int *, int);
2388 
2389 extern int kernel_read(struct file *, loff_t, char *, unsigned long);
2390 extern ssize_t kernel_write(struct file *, const char *, size_t, loff_t);
2391 extern struct file * open_exec(const char *);
2392  
2393 /* fs/dcache.c -- generic fs support functions */
2394 extern int is_subdir(struct dentry *, struct dentry *);
2395 extern int path_is_under(struct path *, struct path *);
2396 
2397 #include <linux/err.h>
2398 
2399 /* needed for stackable file system support */
2400 extern loff_t default_llseek(struct file *file, loff_t offset, int whence);
2401 
2402 extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence);
2403 
2404 extern int inode_init_always(struct super_block *, struct inode *);
2405 extern void inode_init_once(struct inode *);
2406 extern void address_space_init_once(struct address_space *mapping);
2407 extern struct inode * igrab(struct inode *);
2408 extern ino_t iunique(struct super_block *, ino_t);
2409 extern int inode_needs_sync(struct inode *inode);
2410 extern int generic_delete_inode(struct inode *inode);
2411 static inline int generic_drop_inode(struct inode *inode)
2412 {
2413         return !inode->i_nlink || inode_unhashed(inode);
2414 }
2415 
2416 extern struct inode *ilookup5_nowait(struct super_block *sb,
2417                 unsigned long hashval, int (*test)(struct inode *, void *),
2418                 void *data);
2419 extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
2420                 int (*test)(struct inode *, void *), void *data);
2421 extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
2422 
2423 extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
2424 extern struct inode * iget_locked(struct super_block *, unsigned long);
2425 extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
2426 extern int insert_inode_locked(struct inode *);
2427 #ifdef CONFIG_DEBUG_LOCK_ALLOC
2428 extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
2429 #else
2430 static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
2431 #endif
2432 extern void unlock_new_inode(struct inode *);
2433 extern unsigned int get_next_ino(void);
2434 
2435 extern void __iget(struct inode * inode);
2436 extern void iget_failed(struct inode *);
2437 extern void clear_inode(struct inode *);
2438 extern void __destroy_inode(struct inode *);
2439 extern struct inode *new_inode_pseudo(struct super_block *sb);
2440 extern struct inode *new_inode(struct super_block *sb);
2441 extern void free_inode_nonrcu(struct inode *inode);
2442 extern int should_remove_suid(struct dentry *);
2443 extern int file_remove_suid(struct file *);
2444 
2445 extern void __insert_inode_hash(struct inode *, unsigned long hashval);
2446 static inline void insert_inode_hash(struct inode *inode)
2447 {
2448         __insert_inode_hash(inode, inode->i_ino);
2449 }
2450 
2451 extern void __remove_inode_hash(struct inode *);
2452 static inline void remove_inode_hash(struct inode *inode)
2453 {
2454         if (!inode_unhashed(inode))
2455                 __remove_inode_hash(inode);
2456 }
2457 
2458 extern void inode_sb_list_add(struct inode *inode);
2459 
2460 #ifdef CONFIG_BLOCK
2461 extern void submit_bio(int, struct bio *);
2462 extern int bdev_read_only(struct block_device *);
2463 #endif
2464 extern int set_blocksize(struct block_device *, int);
2465 extern int sb_set_blocksize(struct super_block *, int);
2466 extern int sb_min_blocksize(struct super_block *, int);
2467 
2468 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
2469 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
2470 extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
2471                 unsigned long size, pgoff_t pgoff);
2472 extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
2473 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
2474 extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
2475 extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
2476                 loff_t *);
2477 extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
2478 extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
2479                 unsigned long *, loff_t, loff_t *, size_t, size_t);
2480 extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
2481                 unsigned long, loff_t, loff_t *, size_t, ssize_t);
2482 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
2483 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
2484 extern int generic_segment_checks(const struct iovec *iov,
2485                 unsigned long *nr_segs, size_t *count, int access_flags);
2486 
2487 /* fs/block_dev.c */
2488 extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
2489                                 unsigned long nr_segs, loff_t pos);
2490 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
2491                         int datasync);
2492 extern void block_sync_page(struct page *page);
2493 
2494 /* fs/splice.c */
2495 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
2496                 struct pipe_inode_info *, size_t, unsigned int);
2497 extern ssize_t default_file_splice_read(struct file *, loff_t *,
2498                 struct pipe_inode_info *, size_t, unsigned int);
2499 extern ssize_t generic_file_splice_write(struct pipe_inode_info *,
2500                 struct file *, loff_t *, size_t, unsigned int);
2501 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
2502                 struct file *out, loff_t *, size_t len, unsigned int flags);
2503 
2504 extern void
2505 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
2506 extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
2507 extern loff_t no_llseek(struct file *file, loff_t offset, int whence);
2508 extern loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize);
2509 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
2510 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
2511                 int whence, loff_t maxsize, loff_t eof);
2512 extern loff_t fixed_size_llseek(struct file *file, loff_t offset,
2513                 int whence, loff_t size);
2514 extern int generic_file_open(struct inode * inode, struct file * filp);
2515 extern int nonseekable_open(struct inode * inode, struct file * filp);
2516 
2517 #ifdef CONFIG_FS_XIP
2518 extern ssize_t xip_file_read(struct file *filp, char __user *buf, size_t len,
2519                              loff_t *ppos);
2520 extern int xip_file_mmap(struct file * file, struct vm_area_struct * vma);
2521 extern ssize_t xip_file_write(struct file *filp, const char __user *buf,
2522                               size_t len, loff_t *ppos);
2523 extern int xip_truncate_page(struct address_space *mapping, loff_t from);
2524 #else
2525 static inline int xip_truncate_page(struct address_space *mapping, loff_t from)
2526 {
2527         return 0;
2528 }
2529 #endif
2530 
2531 #ifdef CONFIG_BLOCK
2532 typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
2533                             loff_t file_offset);
2534 
2535 enum {
2536         /* need locking between buffered and direct access */
2537         DIO_LOCKING     = 0x01,
2538 
2539         /* filesystem does not support filling holes */
2540         DIO_SKIP_HOLES  = 0x02,
2541 };
2542 
2543 void dio_end_io(struct bio *bio, int error);
2544 
2545 ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
2546         struct block_device *bdev, const struct iovec *iov, loff_t offset,
2547         unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io,
2548         dio_submit_t submit_io, int flags);
2549 
2550 static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
2551                 struct inode *inode, const struct iovec *iov, loff_t offset,
2552                 unsigned long nr_segs, get_block_t get_block)
2553 {
2554         return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
2555                                     offset, nr_segs, get_block, NULL, NULL,
2556                                     DIO_LOCKING | DIO_SKIP_HOLES);
2557 }
2558 #endif
2559 
2560 void inode_dio_wait(struct inode *inode);
2561 void inode_dio_done(struct inode *inode);
2562 
2563 extern const struct file_operations generic_ro_fops;
2564 
2565 #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
2566 
2567 extern int vfs_readlink(struct dentry *, char __user *, int, const char *);
2568 extern int page_readlink(struct dentry *, char __user *, int);
2569 extern void *page_follow_link_light(struct dentry *, struct nameidata *);
2570 extern void page_put_link(struct dentry *, struct nameidata *, void *);
2571 extern int __page_symlink(struct inode *inode, const char *symname, int len,
2572                 int nofs);
2573 extern int page_symlink(struct inode *inode, const char *symname, int len);
2574 extern const struct inode_operations page_symlink_inode_operations;
2575 extern void kfree_put_link(struct dentry *, struct nameidata *, void *);
2576 extern int generic_readlink(struct dentry *, char __user *, int);
2577 extern void generic_fillattr(struct inode *, struct kstat *);
2578 int vfs_getattr_nosec(struct path *path, struct kstat *stat);
2579 extern int vfs_getattr(struct path *, struct kstat *);
2580 void __inode_add_bytes(struct inode *inode, loff_t bytes);
2581 void inode_add_bytes(struct inode *inode, loff_t bytes);
2582 void __inode_sub_bytes(struct inode *inode, loff_t bytes);
2583 void inode_sub_bytes(struct inode *inode, loff_t bytes);
2584 loff_t inode_get_bytes(struct inode *inode);
2585 void inode_set_bytes(struct inode *inode, loff_t bytes);
2586 
2587 extern int vfs_readdir(struct file *, filldir_t, void *);
2588 extern int iterate_dir(struct file *, struct dir_context *);
2589 
2590 extern int vfs_stat(const char __user *, struct kstat *);
2591 extern int vfs_lstat(const char __user *, struct kstat *);
2592 extern int vfs_fstat(unsigned int, struct kstat *);
2593 extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
2594 
2595 extern int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
2596                     unsigned long arg);
2597 extern int __generic_block_fiemap(struct inode *inode,
2598                                   struct fiemap_extent_info *fieinfo,
2599                                   loff_t start, loff_t len,
2600                                   get_block_t *get_block);
2601 extern int generic_block_fiemap(struct inode *inode,
2602                                 struct fiemap_extent_info *fieinfo, u64 start,
2603                                 u64 len, get_block_t *get_block);
2604 
2605 extern void get_filesystem(struct file_system_type *fs);
2606 extern void put_filesystem(struct file_system_type *fs);
2607 extern struct file_system_type *get_fs_type(const char *name);
2608 extern struct super_block *get_super(struct block_device *);
2609 extern struct super_block *get_super_thawed(struct block_device *);
2610 extern struct super_block *get_active_super(struct block_device *bdev);
2611 extern void drop_super(struct super_block *sb);
2612 extern void iterate_supers(void (*)(struct super_block *, void *), void *);
2613 extern void iterate_supers_type(struct file_system_type *,
2614                                 void (*)(struct super_block *, void *), void *);
2615 
2616 extern int dcache_dir_open(struct inode *, struct file *);
2617 extern int dcache_dir_close(struct inode *, struct file *);
2618 extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
2619 extern int dcache_readdir(struct file *, struct dir_context *);
2620 extern int simple_setattr(struct dentry *, struct iattr *);
2621 extern int simple_getattr(struct vfsmount *, struct dentry *, struct kstat *);
2622 extern int simple_statfs(struct dentry *, struct kstatfs *);
2623 extern int simple_open(struct inode *inode, struct file *file);
2624 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
2625 extern int simple_unlink(struct inode *, struct dentry *);
2626 extern int simple_rmdir(struct inode *, struct dentry *);
2627 extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
2628 extern int noop_fsync(struct file *, loff_t, loff_t, int);
2629 extern int simple_empty(struct dentry *);
2630 extern int simple_readpage(struct file *file, struct page *page);
2631 extern int simple_write_begin(struct file *file, struct address_space *mapping,
2632                         loff_t pos, unsigned len, unsigned flags,
2633                         struct page **pagep, void **fsdata);
2634 extern int simple_write_end(struct file *file, struct address_space *mapping,
2635                         loff_t pos, unsigned len, unsigned copied,
2636                         struct page *page, void *fsdata);
2637 extern int always_delete_dentry(const struct dentry *);
2638 extern struct inode *alloc_anon_inode(struct super_block *);
2639 extern const struct dentry_operations simple_dentry_operations;
2640 
2641 extern struct dentry *simple_lookup(struct inode *, struct dentry *, unsigned int flags);
2642 extern ssize_t generic_read_dir(struct file *, char __user *, size_t, loff_t *);
2643 extern const struct file_operations simple_dir_operations;
2644 extern const struct inode_operations simple_dir_inode_operations;
2645 struct tree_descr { char *name; const struct file_operations *ops; int mode; };
2646 struct dentry *d_alloc_name(struct dentry *, const char *);
2647 extern int simple_fill_super(struct super_block *, unsigned long, struct tree_descr *);
2648 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
2649 extern void simple_release_fs(struct vfsmount **mount, int *count);
2650 
2651 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
2652                         loff_t *ppos, const void *from, size_t available);
2653 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
2654                 const void __user *from, size_t count);
2655 
2656 extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
2657 
2658 extern int generic_check_addressable(unsigned, u64);
2659 
2660 #ifdef CONFIG_MIGRATION
2661 extern int buffer_migrate_page(struct address_space *,
2662                                 struct page *, struct page *,
2663                                 enum migrate_mode);
2664 #else
2665 #define buffer_migrate_page NULL
2666 #endif
2667 
2668 extern int inode_change_ok(const struct inode *, struct iattr *);
2669 extern int inode_newsize_ok(const struct inode *, loff_t offset);
2670 extern void setattr_copy(struct inode *inode, const struct iattr *attr);
2671 
2672 extern int file_update_time(struct file *file);
2673 
2674 extern int generic_show_options(struct seq_file *m, struct dentry *root);
2675 extern void save_mount_options(struct super_block *sb, char *options);
2676 extern void replace_mount_options(struct super_block *sb, char *options);
2677 
2678 static inline ino_t parent_ino(struct dentry *dentry)
2679 {
2680         ino_t res;
2681 
2682         /*
2683          * Don't strictly need d_lock here? If the parent ino could change
2684          * then surely we'd have a deeper race in the caller?
2685          */
2686         spin_lock(&dentry->d_lock);
2687         res = dentry->d_parent->d_inode->i_ino;
2688         spin_unlock(&dentry->d_lock);
2689         return res;
2690 }
2691 
2692 /* Transaction based IO helpers */
2693 
2694 /*
2695  * An argresp is stored in an allocated page and holds the
2696  * size of the argument or response, along with its content
2697  */
2698 struct simple_transaction_argresp {
2699         ssize_t size;
2700         char data[0];
2701 };
2702 
2703 #define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))
2704 
2705 char *simple_transaction_get(struct file *file, const char __user *buf,
2706                                 size_t size);
2707 ssize_t simple_transaction_read(struct file *file, char __user *buf,
2708                                 size_t size, loff_t *pos);
2709 int simple_transaction_release(struct inode *inode, struct file *file);
2710 
2711 void simple_transaction_set(struct file *file, size_t n);
2712 
2713 /*
2714  * simple attribute files
2715  *
2716  * These attributes behave similar to those in sysfs:
2717  *
2718  * Writing to an attribute immediately sets a value, an open file can be
2719  * written to multiple times.
2720  *
2721  * Reading from an attribute creates a buffer from the value that might get
2722  * read with multiple read calls. When the attribute has been read
2723  * completely, no further read calls are possible until the file is opened
2724  * again.
2725  *
2726  * All attributes contain a text representation of a numeric value
2727  * that are accessed with the get() and set() functions.
2728  */
2729 #define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)            \
2730 static int __fops ## _open(struct inode *inode, struct file *file)      \
2731 {                                                                       \
2732         __simple_attr_check_format(__fmt, 0ull);                        \
2733         return simple_attr_open(inode, file, __get, __set, __fmt);      \
2734 }                                                                       \
2735 static const struct file_operations __fops = {                          \
2736         .owner   = THIS_MODULE,                                         \
2737         .open    = __fops ## _open,                                     \
2738         .release = simple_attr_release,                                 \
2739         .read    = simple_attr_read,                                    \
2740         .write   = simple_attr_write,                                   \
2741         .llseek  = generic_file_llseek,                                 \
2742 };
2743 
2744 static inline __printf(1, 2)
2745 void __simple_attr_check_format(const char *fmt, ...)
2746 {
2747         /* don't do anything, just let the compiler check the arguments; */
2748 }
2749 
2750 int simple_attr_open(struct inode *inode, struct file *file,
2751                      int (*get)(void *, u64 *), int (*set)(void *, u64),
2752                      const char *fmt);
2753 int simple_attr_release(struct inode *inode, struct file *file);
2754 ssize_t simple_attr_read(struct file *file, char __user *buf,
2755                          size_t len, loff_t *ppos);
2756 ssize_t simple_attr_write(struct file *file, const char __user *buf,
2757                           size_t len, loff_t *ppos);
2758 
2759 struct ctl_table;
2760 int proc_nr_files(struct ctl_table *table, int write,
2761                   void __user *buffer, size_t *lenp, loff_t *ppos);
2762 int proc_nr_dentry(struct ctl_table *table, int write,
2763                   void __user *buffer, size_t *lenp, loff_t *ppos);
2764 int proc_nr_inodes(struct ctl_table *table, int write,
2765                    void __user *buffer, size_t *lenp, loff_t *ppos);
2766 int __init get_filesystem_list(char *buf);
2767 
2768 #define __FMODE_EXEC            ((__force int) FMODE_EXEC)
2769 #define __FMODE_NONOTIFY        ((__force int) FMODE_NONOTIFY)
2770 
2771 #define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
2772 #define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
2773                                             (flag & __FMODE_NONOTIFY)))
2774 
2775 static inline int is_sxid(umode_t mode)
2776 {
2777         return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
2778 }
2779 
2780 static inline void inode_has_no_xattr(struct inode *inode)
2781 {
2782         if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))
2783                 inode->i_flags |= S_NOSEC;
2784 }
2785 
2786 static inline bool dir_emit(struct dir_context *ctx,
2787                             const char *name, int namelen,
2788                             u64 ino, unsigned type)
2789 {
2790         return ctx->actor(ctx, name, namelen, ctx->pos, ino, type) == 0;
2791 }
2792 static inline bool dir_emit_dot(struct file *file, struct dir_context *ctx)
2793 {
2794         return ctx->actor(ctx, ".", 1, ctx->pos,
2795                           file->f_path.dentry->d_inode->i_ino, DT_DIR) == 0;
2796 }
2797 static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
2798 {
2799         return ctx->actor(ctx, "..", 2, ctx->pos,
2800                           parent_ino(file->f_path.dentry), DT_DIR) == 0;
2801 }
2802 static inline bool dir_emit_dots(struct file *file, struct dir_context *ctx)
2803 {
2804         if (ctx->pos == 0) {
2805                 if (!dir_emit_dot(file, ctx))
2806                         return false;
2807                 ctx->pos = 1;
2808         }
2809         if (ctx->pos == 1) {
2810                 if (!dir_emit_dotdot(file, ctx))
2811                         return false;
2812                 ctx->pos = 2;
2813         }
2814         return true;
2815 }
2816 static inline bool dir_relax(struct inode *inode)
2817 {
2818         mutex_unlock(&inode->i_mutex);
2819         mutex_lock(&inode->i_mutex);
2820         return !IS_DEADDIR(inode);
2821 }
2822 
2823 #endif /* _LINUX_FS_H */
2824 

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