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TOMOYO Linux Cross Reference
Linux/include/linux/fs.h

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  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 struct iov_iter;
 52 
 53 extern void __init inode_init(void);
 54 extern void __init inode_init_early(void);
 55 extern void __init files_init(unsigned long);
 56 
 57 extern struct files_stat_struct files_stat;
 58 extern unsigned long get_max_files(void);
 59 extern int sysctl_nr_open;
 60 extern struct inodes_stat_t inodes_stat;
 61 extern int leases_enable, lease_break_time;
 62 extern int sysctl_protected_symlinks;
 63 extern int sysctl_protected_hardlinks;
 64 
 65 struct buffer_head;
 66 typedef int (get_block_t)(struct inode *inode, sector_t iblock,
 67                         struct buffer_head *bh_result, int create);
 68 typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 69                         ssize_t bytes, void *private);
 70 
 71 #define MAY_EXEC                0x00000001
 72 #define MAY_WRITE               0x00000002
 73 #define MAY_READ                0x00000004
 74 #define MAY_APPEND              0x00000008
 75 #define MAY_ACCESS              0x00000010
 76 #define MAY_OPEN                0x00000020
 77 #define MAY_CHDIR               0x00000040
 78 /* called from RCU mode, don't block */
 79 #define MAY_NOT_BLOCK           0x00000080
 80 
 81 /*
 82  * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
 83  * to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
 84  */
 85 
 86 /* file is open for reading */
 87 #define FMODE_READ              ((__force fmode_t)0x1)
 88 /* file is open for writing */
 89 #define FMODE_WRITE             ((__force fmode_t)0x2)
 90 /* file is seekable */
 91 #define FMODE_LSEEK             ((__force fmode_t)0x4)
 92 /* file can be accessed using pread */
 93 #define FMODE_PREAD             ((__force fmode_t)0x8)
 94 /* file can be accessed using pwrite */
 95 #define FMODE_PWRITE            ((__force fmode_t)0x10)
 96 /* File is opened for execution with sys_execve / sys_uselib */
 97 #define FMODE_EXEC              ((__force fmode_t)0x20)
 98 /* File is opened with O_NDELAY (only set for block devices) */
 99 #define FMODE_NDELAY            ((__force fmode_t)0x40)
100 /* File is opened with O_EXCL (only set for block devices) */
101 #define FMODE_EXCL              ((__force fmode_t)0x80)
102 /* File is opened using open(.., 3, ..) and is writeable only for ioctls
103    (specialy hack for floppy.c) */
104 #define FMODE_WRITE_IOCTL       ((__force fmode_t)0x100)
105 /* 32bit hashes as llseek() offset (for directories) */
106 #define FMODE_32BITHASH         ((__force fmode_t)0x200)
107 /* 64bit hashes as llseek() offset (for directories) */
108 #define FMODE_64BITHASH         ((__force fmode_t)0x400)
109 
110 /*
111  * Don't update ctime and mtime.
112  *
113  * Currently a special hack for the XFS open_by_handle ioctl, but we'll
114  * hopefully graduate it to a proper O_CMTIME flag supported by open(2) soon.
115  */
116 #define FMODE_NOCMTIME          ((__force fmode_t)0x800)
117 
118 /* Expect random access pattern */
119 #define FMODE_RANDOM            ((__force fmode_t)0x1000)
120 
121 /* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
122 #define FMODE_UNSIGNED_OFFSET   ((__force fmode_t)0x2000)
123 
124 /* File is opened with O_PATH; almost nothing can be done with it */
125 #define FMODE_PATH              ((__force fmode_t)0x4000)
126 
127 /* File needs atomic accesses to f_pos */
128 #define FMODE_ATOMIC_POS        ((__force fmode_t)0x8000)
129 /* Write access to underlying fs */
130 #define FMODE_WRITER            ((__force fmode_t)0x10000)
131 /* Has read method(s) */
132 #define FMODE_CAN_READ          ((__force fmode_t)0x20000)
133 /* Has write method(s) */
134 #define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)
135 
136 /* File was opened by fanotify and shouldn't generate fanotify events */
137 #define FMODE_NONOTIFY          ((__force fmode_t)0x1000000)
138 
139 /*
140  * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
141  * that indicates that they should check the contents of the iovec are
142  * valid, but not check the memory that the iovec elements
143  * points too.
144  */
145 #define CHECK_IOVEC_ONLY -1
146 
147 /*
148  * The below are the various read and write types that we support. Some of
149  * them include behavioral modifiers that send information down to the
150  * block layer and IO scheduler. Terminology:
151  *
152  *      The block layer uses device plugging to defer IO a little bit, in
153  *      the hope that we will see more IO very shortly. This increases
154  *      coalescing of adjacent IO and thus reduces the number of IOs we
155  *      have to send to the device. It also allows for better queuing,
156  *      if the IO isn't mergeable. If the caller is going to be waiting
157  *      for the IO, then he must ensure that the device is unplugged so
158  *      that the IO is dispatched to the driver.
159  *
160  *      All IO is handled async in Linux. This is fine for background
161  *      writes, but for reads or writes that someone waits for completion
162  *      on, we want to notify the block layer and IO scheduler so that they
163  *      know about it. That allows them to make better scheduling
164  *      decisions. So when the below references 'sync' and 'async', it
165  *      is referencing this priority hint.
166  *
167  * With that in mind, the available types are:
168  *
169  * READ                 A normal read operation. Device will be plugged.
170  * READ_SYNC            A synchronous read. Device is not plugged, caller can
171  *                      immediately wait on this read without caring about
172  *                      unplugging.
173  * READA                Used for read-ahead operations. Lower priority, and the
174  *                      block layer could (in theory) choose to ignore this
175  *                      request if it runs into resource problems.
176  * WRITE                A normal async write. Device will be plugged.
177  * WRITE_SYNC           Synchronous write. Identical to WRITE, but passes down
178  *                      the hint that someone will be waiting on this IO
179  *                      shortly. The write equivalent of READ_SYNC.
180  * WRITE_ODIRECT        Special case write for O_DIRECT only.
181  * WRITE_FLUSH          Like WRITE_SYNC but with preceding cache flush.
182  * WRITE_FUA            Like WRITE_SYNC but data is guaranteed to be on
183  *                      non-volatile media on completion.
184  * WRITE_FLUSH_FUA      Combination of WRITE_FLUSH and FUA. The IO is preceded
185  *                      by a cache flush and data is guaranteed to be on
186  *                      non-volatile media on completion.
187  *
188  */
189 #define RW_MASK                 REQ_WRITE
190 #define RWA_MASK                REQ_RAHEAD
191 
192 #define READ                    0
193 #define WRITE                   RW_MASK
194 #define READA                   RWA_MASK
195 
196 #define READ_SYNC               (READ | REQ_SYNC)
197 #define WRITE_SYNC              (WRITE | REQ_SYNC | REQ_NOIDLE)
198 #define WRITE_ODIRECT           (WRITE | REQ_SYNC)
199 #define WRITE_FLUSH             (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH)
200 #define WRITE_FUA               (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FUA)
201 #define WRITE_FLUSH_FUA         (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)
202 
203 /*
204  * Attribute flags.  These should be or-ed together to figure out what
205  * has been changed!
206  */
207 #define ATTR_MODE       (1 << 0)
208 #define ATTR_UID        (1 << 1)
209 #define ATTR_GID        (1 << 2)
210 #define ATTR_SIZE       (1 << 3)
211 #define ATTR_ATIME      (1 << 4)
212 #define ATTR_MTIME      (1 << 5)
213 #define ATTR_CTIME      (1 << 6)
214 #define ATTR_ATIME_SET  (1 << 7)
215 #define ATTR_MTIME_SET  (1 << 8)
216 #define ATTR_FORCE      (1 << 9) /* Not a change, but a change it */
217 #define ATTR_ATTR_FLAG  (1 << 10)
218 #define ATTR_KILL_SUID  (1 << 11)
219 #define ATTR_KILL_SGID  (1 << 12)
220 #define ATTR_FILE       (1 << 13)
221 #define ATTR_KILL_PRIV  (1 << 14)
222 #define ATTR_OPEN       (1 << 15) /* Truncating from open(O_TRUNC) */
223 #define ATTR_TIMES_SET  (1 << 16)
224 
225 /*
226  * Whiteout is represented by a char device.  The following constants define the
227  * mode and device number to use.
228  */
229 #define WHITEOUT_MODE 0
230 #define WHITEOUT_DEV 0
231 
232 /*
233  * This is the Inode Attributes structure, used for notify_change().  It
234  * uses the above definitions as flags, to know which values have changed.
235  * Also, in this manner, a Filesystem can look at only the values it cares
236  * about.  Basically, these are the attributes that the VFS layer can
237  * request to change from the FS layer.
238  *
239  * Derek Atkins <warlord@MIT.EDU> 94-10-20
240  */
241 struct iattr {
242         unsigned int    ia_valid;
243         umode_t         ia_mode;
244         kuid_t          ia_uid;
245         kgid_t          ia_gid;
246         loff_t          ia_size;
247         struct timespec ia_atime;
248         struct timespec ia_mtime;
249         struct timespec ia_ctime;
250 
251         /*
252          * Not an attribute, but an auxiliary info for filesystems wanting to
253          * implement an ftruncate() like method.  NOTE: filesystem should
254          * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
255          */
256         struct file     *ia_file;
257 };
258 
259 /*
260  * Includes for diskquotas.
261  */
262 #include <linux/quota.h>
263 
264 /*
265  * Maximum number of layers of fs stack.  Needs to be limited to
266  * prevent kernel stack overflow
267  */
268 #define FILESYSTEM_MAX_STACK_DEPTH 2
269 
270 /** 
271  * enum positive_aop_returns - aop return codes with specific semantics
272  *
273  * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
274  *                          completed, that the page is still locked, and
275  *                          should be considered active.  The VM uses this hint
276  *                          to return the page to the active list -- it won't
277  *                          be a candidate for writeback again in the near
278  *                          future.  Other callers must be careful to unlock
279  *                          the page if they get this return.  Returned by
280  *                          writepage(); 
281  *
282  * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
283  *                      unlocked it and the page might have been truncated.
284  *                      The caller should back up to acquiring a new page and
285  *                      trying again.  The aop will be taking reasonable
286  *                      precautions not to livelock.  If the caller held a page
287  *                      reference, it should drop it before retrying.  Returned
288  *                      by readpage().
289  *
290  * address_space_operation functions return these large constants to indicate
291  * special semantics to the caller.  These are much larger than the bytes in a
292  * page to allow for functions that return the number of bytes operated on in a
293  * given page.
294  */
295 
296 enum positive_aop_returns {
297         AOP_WRITEPAGE_ACTIVATE  = 0x80000,
298         AOP_TRUNCATED_PAGE      = 0x80001,
299 };
300 
301 #define AOP_FLAG_UNINTERRUPTIBLE        0x0001 /* will not do a short write */
302 #define AOP_FLAG_CONT_EXPAND            0x0002 /* called from cont_expand */
303 #define AOP_FLAG_NOFS                   0x0004 /* used by filesystem to direct
304                                                 * helper code (eg buffer layer)
305                                                 * to clear GFP_FS from alloc */
306 
307 /*
308  * oh the beauties of C type declarations.
309  */
310 struct page;
311 struct address_space;
312 struct writeback_control;
313 
314 /*
315  * "descriptor" for what we're up to with a read.
316  * This allows us to use the same read code yet
317  * have multiple different users of the data that
318  * we read from a file.
319  *
320  * The simplest case just copies the data to user
321  * mode.
322  */
323 typedef struct {
324         size_t written;
325         size_t count;
326         union {
327                 char __user *buf;
328                 void *data;
329         } arg;
330         int error;
331 } read_descriptor_t;
332 
333 typedef int (*read_actor_t)(read_descriptor_t *, struct page *,
334                 unsigned long, unsigned long);
335 
336 struct address_space_operations {
337         int (*writepage)(struct page *page, struct writeback_control *wbc);
338         int (*readpage)(struct file *, struct page *);
339 
340         /* Write back some dirty pages from this mapping. */
341         int (*writepages)(struct address_space *, struct writeback_control *);
342 
343         /* Set a page dirty.  Return true if this dirtied it */
344         int (*set_page_dirty)(struct page *page);
345 
346         int (*readpages)(struct file *filp, struct address_space *mapping,
347                         struct list_head *pages, unsigned nr_pages);
348 
349         int (*write_begin)(struct file *, struct address_space *mapping,
350                                 loff_t pos, unsigned len, unsigned flags,
351                                 struct page **pagep, void **fsdata);
352         int (*write_end)(struct file *, struct address_space *mapping,
353                                 loff_t pos, unsigned len, unsigned copied,
354                                 struct page *page, void *fsdata);
355 
356         /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
357         sector_t (*bmap)(struct address_space *, sector_t);
358         void (*invalidatepage) (struct page *, unsigned int, unsigned int);
359         int (*releasepage) (struct page *, gfp_t);
360         void (*freepage)(struct page *);
361         ssize_t (*direct_IO)(int, struct kiocb *, struct iov_iter *iter, loff_t offset);
362         int (*get_xip_mem)(struct address_space *, pgoff_t, int,
363                                                 void **, unsigned long *);
364         /*
365          * migrate the contents of a page to the specified target. If
366          * migrate_mode is MIGRATE_ASYNC, it must not block.
367          */
368         int (*migratepage) (struct address_space *,
369                         struct page *, struct page *, enum migrate_mode);
370         int (*launder_page) (struct page *);
371         int (*is_partially_uptodate) (struct page *, unsigned long,
372                                         unsigned long);
373         void (*is_dirty_writeback) (struct page *, bool *, bool *);
374         int (*error_remove_page)(struct address_space *, struct page *);
375 
376         /* swapfile support */
377         int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
378                                 sector_t *span);
379         void (*swap_deactivate)(struct file *file);
380 };
381 
382 extern const struct address_space_operations empty_aops;
383 
384 /*
385  * pagecache_write_begin/pagecache_write_end must be used by general code
386  * to write into the pagecache.
387  */
388 int pagecache_write_begin(struct file *, struct address_space *mapping,
389                                 loff_t pos, unsigned len, unsigned flags,
390                                 struct page **pagep, void **fsdata);
391 
392 int pagecache_write_end(struct file *, struct address_space *mapping,
393                                 loff_t pos, unsigned len, unsigned copied,
394                                 struct page *page, void *fsdata);
395 
396 struct backing_dev_info;
397 struct address_space {
398         struct inode            *host;          /* owner: inode, block_device */
399         struct radix_tree_root  page_tree;      /* radix tree of all pages */
400         spinlock_t              tree_lock;      /* and lock protecting it */
401         atomic_t                i_mmap_writable;/* count VM_SHARED mappings */
402         struct rb_root          i_mmap;         /* tree of private and shared mappings */
403         struct list_head        i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
404         struct mutex            i_mmap_mutex;   /* protect tree, count, list */
405         /* Protected by tree_lock together with the radix tree */
406         unsigned long           nrpages;        /* number of total pages */
407         unsigned long           nrshadows;      /* number of shadow entries */
408         pgoff_t                 writeback_index;/* writeback starts here */
409         const struct address_space_operations *a_ops;   /* methods */
410         unsigned long           flags;          /* error bits/gfp mask */
411         struct backing_dev_info *backing_dev_info; /* device readahead, etc */
412         spinlock_t              private_lock;   /* for use by the address_space */
413         struct list_head        private_list;   /* ditto */
414         void                    *private_data;  /* ditto */
415 } __attribute__((aligned(sizeof(long))));
416         /*
417          * On most architectures that alignment is already the case; but
418          * must be enforced here for CRIS, to let the least significant bit
419          * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
420          */
421 struct request_queue;
422 
423 struct block_device {
424         dev_t                   bd_dev;  /* not a kdev_t - it's a search key */
425         int                     bd_openers;
426         struct inode *          bd_inode;       /* will die */
427         struct super_block *    bd_super;
428         struct mutex            bd_mutex;       /* open/close mutex */
429         struct list_head        bd_inodes;
430         void *                  bd_claiming;
431         void *                  bd_holder;
432         int                     bd_holders;
433         bool                    bd_write_holder;
434 #ifdef CONFIG_SYSFS
435         struct list_head        bd_holder_disks;
436 #endif
437         struct block_device *   bd_contains;
438         unsigned                bd_block_size;
439         struct hd_struct *      bd_part;
440         /* number of times partitions within this device have been opened. */
441         unsigned                bd_part_count;
442         int                     bd_invalidated;
443         struct gendisk *        bd_disk;
444         struct request_queue *  bd_queue;
445         struct list_head        bd_list;
446         /*
447          * Private data.  You must have bd_claim'ed the block_device
448          * to use this.  NOTE:  bd_claim allows an owner to claim
449          * the same device multiple times, the owner must take special
450          * care to not mess up bd_private for that case.
451          */
452         unsigned long           bd_private;
453 
454         /* The counter of freeze processes */
455         int                     bd_fsfreeze_count;
456         /* Mutex for freeze */
457         struct mutex            bd_fsfreeze_mutex;
458 };
459 
460 /*
461  * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
462  * radix trees
463  */
464 #define PAGECACHE_TAG_DIRTY     0
465 #define PAGECACHE_TAG_WRITEBACK 1
466 #define PAGECACHE_TAG_TOWRITE   2
467 
468 int mapping_tagged(struct address_space *mapping, int tag);
469 
470 /*
471  * Might pages of this file be mapped into userspace?
472  */
473 static inline int mapping_mapped(struct address_space *mapping)
474 {
475         return  !RB_EMPTY_ROOT(&mapping->i_mmap) ||
476                 !list_empty(&mapping->i_mmap_nonlinear);
477 }
478 
479 /*
480  * Might pages of this file have been modified in userspace?
481  * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
482  * marks vma as VM_SHARED if it is shared, and the file was opened for
483  * writing i.e. vma may be mprotected writable even if now readonly.
484  *
485  * If i_mmap_writable is negative, no new writable mappings are allowed. You
486  * can only deny writable mappings, if none exists right now.
487  */
488 static inline int mapping_writably_mapped(struct address_space *mapping)
489 {
490         return atomic_read(&mapping->i_mmap_writable) > 0;
491 }
492 
493 static inline int mapping_map_writable(struct address_space *mapping)
494 {
495         return atomic_inc_unless_negative(&mapping->i_mmap_writable) ?
496                 0 : -EPERM;
497 }
498 
499 static inline void mapping_unmap_writable(struct address_space *mapping)
500 {
501         atomic_dec(&mapping->i_mmap_writable);
502 }
503 
504 static inline int mapping_deny_writable(struct address_space *mapping)
505 {
506         return atomic_dec_unless_positive(&mapping->i_mmap_writable) ?
507                 0 : -EBUSY;
508 }
509 
510 static inline void mapping_allow_writable(struct address_space *mapping)
511 {
512         atomic_inc(&mapping->i_mmap_writable);
513 }
514 
515 /*
516  * Use sequence counter to get consistent i_size on 32-bit processors.
517  */
518 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
519 #include <linux/seqlock.h>
520 #define __NEED_I_SIZE_ORDERED
521 #define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
522 #else
523 #define i_size_ordered_init(inode) do { } while (0)
524 #endif
525 
526 struct posix_acl;
527 #define ACL_NOT_CACHED ((void *)(-1))
528 
529 #define IOP_FASTPERM    0x0001
530 #define IOP_LOOKUP      0x0002
531 #define IOP_NOFOLLOW    0x0004
532 
533 /*
534  * Keep mostly read-only and often accessed (especially for
535  * the RCU path lookup and 'stat' data) fields at the beginning
536  * of the 'struct inode'
537  */
538 struct inode {
539         umode_t                 i_mode;
540         unsigned short          i_opflags;
541         kuid_t                  i_uid;
542         kgid_t                  i_gid;
543         unsigned int            i_flags;
544 
545 #ifdef CONFIG_FS_POSIX_ACL
546         struct posix_acl        *i_acl;
547         struct posix_acl        *i_default_acl;
548 #endif
549 
550         const struct inode_operations   *i_op;
551         struct super_block      *i_sb;
552         struct address_space    *i_mapping;
553 
554 #ifdef CONFIG_SECURITY
555         void                    *i_security;
556 #endif
557 
558         /* Stat data, not accessed from path walking */
559         unsigned long           i_ino;
560         /*
561          * Filesystems may only read i_nlink directly.  They shall use the
562          * following functions for modification:
563          *
564          *    (set|clear|inc|drop)_nlink
565          *    inode_(inc|dec)_link_count
566          */
567         union {
568                 const unsigned int i_nlink;
569                 unsigned int __i_nlink;
570         };
571         dev_t                   i_rdev;
572         loff_t                  i_size;
573         struct timespec         i_atime;
574         struct timespec         i_mtime;
575         struct timespec         i_ctime;
576         spinlock_t              i_lock; /* i_blocks, i_bytes, maybe i_size */
577         unsigned short          i_bytes;
578         unsigned int            i_blkbits;
579         blkcnt_t                i_blocks;
580 
581 #ifdef __NEED_I_SIZE_ORDERED
582         seqcount_t              i_size_seqcount;
583 #endif
584 
585         /* Misc */
586         unsigned long           i_state;
587         struct mutex            i_mutex;
588 
589         unsigned long           dirtied_when;   /* jiffies of first dirtying */
590 
591         struct hlist_node       i_hash;
592         struct list_head        i_wb_list;      /* backing dev IO list */
593         struct list_head        i_lru;          /* inode LRU list */
594         struct list_head        i_sb_list;
595         union {
596                 struct hlist_head       i_dentry;
597                 struct rcu_head         i_rcu;
598         };
599         u64                     i_version;
600         atomic_t                i_count;
601         atomic_t                i_dio_count;
602         atomic_t                i_writecount;
603 #ifdef CONFIG_IMA
604         atomic_t                i_readcount; /* struct files open RO */
605 #endif
606         const struct file_operations    *i_fop; /* former ->i_op->default_file_ops */
607         struct file_lock        *i_flock;
608         struct address_space    i_data;
609 #ifdef CONFIG_QUOTA
610         struct dquot            *i_dquot[MAXQUOTAS];
611 #endif
612         struct list_head        i_devices;
613         union {
614                 struct pipe_inode_info  *i_pipe;
615                 struct block_device     *i_bdev;
616                 struct cdev             *i_cdev;
617         };
618 
619         __u32                   i_generation;
620 
621 #ifdef CONFIG_FSNOTIFY
622         __u32                   i_fsnotify_mask; /* all events this inode cares about */
623         struct hlist_head       i_fsnotify_marks;
624 #endif
625 
626         void                    *i_private; /* fs or device private pointer */
627 };
628 
629 static inline int inode_unhashed(struct inode *inode)
630 {
631         return hlist_unhashed(&inode->i_hash);
632 }
633 
634 /*
635  * inode->i_mutex nesting subclasses for the lock validator:
636  *
637  * 0: the object of the current VFS operation
638  * 1: parent
639  * 2: child/target
640  * 3: xattr
641  * 4: second non-directory
642  * 5: second parent (when locking independent directories in rename)
643  *
644  * I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
645  * non-directories at once.
646  *
647  * The locking order between these classes is
648  * parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
649  */
650 enum inode_i_mutex_lock_class
651 {
652         I_MUTEX_NORMAL,
653         I_MUTEX_PARENT,
654         I_MUTEX_CHILD,
655         I_MUTEX_XATTR,
656         I_MUTEX_NONDIR2,
657         I_MUTEX_PARENT2,
658 };
659 
660 void lock_two_nondirectories(struct inode *, struct inode*);
661 void unlock_two_nondirectories(struct inode *, struct inode*);
662 
663 /*
664  * NOTE: in a 32bit arch with a preemptable kernel and
665  * an UP compile the i_size_read/write must be atomic
666  * with respect to the local cpu (unlike with preempt disabled),
667  * but they don't need to be atomic with respect to other cpus like in
668  * true SMP (so they need either to either locally disable irq around
669  * the read or for example on x86 they can be still implemented as a
670  * cmpxchg8b without the need of the lock prefix). For SMP compiles
671  * and 64bit archs it makes no difference if preempt is enabled or not.
672  */
673 static inline loff_t i_size_read(const struct inode *inode)
674 {
675 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
676         loff_t i_size;
677         unsigned int seq;
678 
679         do {
680                 seq = read_seqcount_begin(&inode->i_size_seqcount);
681                 i_size = inode->i_size;
682         } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
683         return i_size;
684 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
685         loff_t i_size;
686 
687         preempt_disable();
688         i_size = inode->i_size;
689         preempt_enable();
690         return i_size;
691 #else
692         return inode->i_size;
693 #endif
694 }
695 
696 /*
697  * NOTE: unlike i_size_read(), i_size_write() does need locking around it
698  * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
699  * can be lost, resulting in subsequent i_size_read() calls spinning forever.
700  */
701 static inline void i_size_write(struct inode *inode, loff_t i_size)
702 {
703 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
704         preempt_disable();
705         write_seqcount_begin(&inode->i_size_seqcount);
706         inode->i_size = i_size;
707         write_seqcount_end(&inode->i_size_seqcount);
708         preempt_enable();
709 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
710         preempt_disable();
711         inode->i_size = i_size;
712         preempt_enable();
713 #else
714         inode->i_size = i_size;
715 #endif
716 }
717 
718 /* Helper functions so that in most cases filesystems will
719  * not need to deal directly with kuid_t and kgid_t and can
720  * instead deal with the raw numeric values that are stored
721  * in the filesystem.
722  */
723 static inline uid_t i_uid_read(const struct inode *inode)
724 {
725         return from_kuid(&init_user_ns, inode->i_uid);
726 }
727 
728 static inline gid_t i_gid_read(const struct inode *inode)
729 {
730         return from_kgid(&init_user_ns, inode->i_gid);
731 }
732 
733 static inline void i_uid_write(struct inode *inode, uid_t uid)
734 {
735         inode->i_uid = make_kuid(&init_user_ns, uid);
736 }
737 
738 static inline void i_gid_write(struct inode *inode, gid_t gid)
739 {
740         inode->i_gid = make_kgid(&init_user_ns, gid);
741 }
742 
743 static inline unsigned iminor(const struct inode *inode)
744 {
745         return MINOR(inode->i_rdev);
746 }
747 
748 static inline unsigned imajor(const struct inode *inode)
749 {
750         return MAJOR(inode->i_rdev);
751 }
752 
753 extern struct block_device *I_BDEV(struct inode *inode);
754 
755 struct fown_struct {
756         rwlock_t lock;          /* protects pid, uid, euid fields */
757         struct pid *pid;        /* pid or -pgrp where SIGIO should be sent */
758         enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
759         kuid_t uid, euid;       /* uid/euid of process setting the owner */
760         int signum;             /* posix.1b rt signal to be delivered on IO */
761 };
762 
763 /*
764  * Track a single file's readahead state
765  */
766 struct file_ra_state {
767         pgoff_t start;                  /* where readahead started */
768         unsigned int size;              /* # of readahead pages */
769         unsigned int async_size;        /* do asynchronous readahead when
770                                            there are only # of pages ahead */
771 
772         unsigned int ra_pages;          /* Maximum readahead window */
773         unsigned int mmap_miss;         /* Cache miss stat for mmap accesses */
774         loff_t prev_pos;                /* Cache last read() position */
775 };
776 
777 /*
778  * Check if @index falls in the readahead windows.
779  */
780 static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
781 {
782         return (index >= ra->start &&
783                 index <  ra->start + ra->size);
784 }
785 
786 struct file {
787         union {
788                 struct llist_node       fu_llist;
789                 struct rcu_head         fu_rcuhead;
790         } f_u;
791         struct path             f_path;
792 #define f_dentry        f_path.dentry
793         struct inode            *f_inode;       /* cached value */
794         const struct file_operations    *f_op;
795 
796         /*
797          * Protects f_ep_links, f_flags.
798          * Must not be taken from IRQ context.
799          */
800         spinlock_t              f_lock;
801         atomic_long_t           f_count;
802         unsigned int            f_flags;
803         fmode_t                 f_mode;
804         struct mutex            f_pos_lock;
805         loff_t                  f_pos;
806         struct fown_struct      f_owner;
807         const struct cred       *f_cred;
808         struct file_ra_state    f_ra;
809 
810         u64                     f_version;
811 #ifdef CONFIG_SECURITY
812         void                    *f_security;
813 #endif
814         /* needed for tty driver, and maybe others */
815         void                    *private_data;
816 
817 #ifdef CONFIG_EPOLL
818         /* Used by fs/eventpoll.c to link all the hooks to this file */
819         struct list_head        f_ep_links;
820         struct list_head        f_tfile_llink;
821 #endif /* #ifdef CONFIG_EPOLL */
822         struct address_space    *f_mapping;
823 } __attribute__((aligned(4)));  /* lest something weird decides that 2 is OK */
824 
825 struct file_handle {
826         __u32 handle_bytes;
827         int handle_type;
828         /* file identifier */
829         unsigned char f_handle[0];
830 };
831 
832 static inline struct file *get_file(struct file *f)
833 {
834         atomic_long_inc(&f->f_count);
835         return f;
836 }
837 #define fput_atomic(x)  atomic_long_add_unless(&(x)->f_count, -1, 1)
838 #define file_count(x)   atomic_long_read(&(x)->f_count)
839 
840 #define MAX_NON_LFS     ((1UL<<31) - 1)
841 
842 /* Page cache limit. The filesystems should put that into their s_maxbytes 
843    limits, otherwise bad things can happen in VM. */ 
844 #if BITS_PER_LONG==32
845 #define MAX_LFS_FILESIZE        (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1) 
846 #elif BITS_PER_LONG==64
847 #define MAX_LFS_FILESIZE        ((loff_t)0x7fffffffffffffffLL)
848 #endif
849 
850 #define FL_POSIX        1
851 #define FL_FLOCK        2
852 #define FL_DELEG        4       /* NFSv4 delegation */
853 #define FL_ACCESS       8       /* not trying to lock, just looking */
854 #define FL_EXISTS       16      /* when unlocking, test for existence */
855 #define FL_LEASE        32      /* lease held on this file */
856 #define FL_CLOSE        64      /* unlock on close */
857 #define FL_SLEEP        128     /* A blocking lock */
858 #define FL_DOWNGRADE_PENDING    256 /* Lease is being downgraded */
859 #define FL_UNLOCK_PENDING       512 /* Lease is being broken */
860 #define FL_OFDLCK       1024    /* lock is "owned" by struct file */
861 
862 /*
863  * Special return value from posix_lock_file() and vfs_lock_file() for
864  * asynchronous locking.
865  */
866 #define FILE_LOCK_DEFERRED 1
867 
868 /* legacy typedef, should eventually be removed */
869 typedef void *fl_owner_t;
870 
871 struct file_lock_operations {
872         void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
873         void (*fl_release_private)(struct file_lock *);
874 };
875 
876 struct lock_manager_operations {
877         int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
878         unsigned long (*lm_owner_key)(struct file_lock *);
879         void (*lm_get_owner)(struct file_lock *, struct file_lock *);
880         void (*lm_put_owner)(struct file_lock *);
881         void (*lm_notify)(struct file_lock *);  /* unblock callback */
882         int (*lm_grant)(struct file_lock *, int);
883         bool (*lm_break)(struct file_lock *);
884         int (*lm_change)(struct file_lock **, int, struct list_head *);
885         void (*lm_setup)(struct file_lock *, void **);
886 };
887 
888 struct lock_manager {
889         struct list_head list;
890 };
891 
892 struct net;
893 void locks_start_grace(struct net *, struct lock_manager *);
894 void locks_end_grace(struct lock_manager *);
895 int locks_in_grace(struct net *);
896 
897 /* that will die - we need it for nfs_lock_info */
898 #include <linux/nfs_fs_i.h>
899 
900 /*
901  * struct file_lock represents a generic "file lock". It's used to represent
902  * POSIX byte range locks, BSD (flock) locks, and leases. It's important to
903  * note that the same struct is used to represent both a request for a lock and
904  * the lock itself, but the same object is never used for both.
905  *
906  * FIXME: should we create a separate "struct lock_request" to help distinguish
907  * these two uses?
908  *
909  * The varous i_flctx lists are ordered by:
910  *
911  * 1) lock owner
912  * 2) lock range start
913  * 3) lock range end
914  *
915  * Obviously, the last two criteria only matter for POSIX locks.
916  */
917 struct file_lock {
918         struct file_lock *fl_next;      /* singly linked list for this inode  */
919         struct hlist_node fl_link;      /* node in global lists */
920         struct list_head fl_block;      /* circular list of blocked processes */
921         fl_owner_t fl_owner;
922         unsigned int fl_flags;
923         unsigned char fl_type;
924         unsigned int fl_pid;
925         int fl_link_cpu;                /* what cpu's list is this on? */
926         struct pid *fl_nspid;
927         wait_queue_head_t fl_wait;
928         struct file *fl_file;
929         loff_t fl_start;
930         loff_t fl_end;
931 
932         struct fasync_struct *  fl_fasync; /* for lease break notifications */
933         /* for lease breaks: */
934         unsigned long fl_break_time;
935         unsigned long fl_downgrade_time;
936 
937         const struct file_lock_operations *fl_ops;      /* Callbacks for filesystems */
938         const struct lock_manager_operations *fl_lmops; /* Callbacks for lockmanagers */
939         union {
940                 struct nfs_lock_info    nfs_fl;
941                 struct nfs4_lock_info   nfs4_fl;
942                 struct {
943                         struct list_head link;  /* link in AFS vnode's pending_locks list */
944                         int state;              /* state of grant or error if -ve */
945                 } afs;
946         } fl_u;
947 };
948 
949 /* The following constant reflects the upper bound of the file/locking space */
950 #ifndef OFFSET_MAX
951 #define INT_LIMIT(x)    (~((x)1 << (sizeof(x)*8 - 1)))
952 #define OFFSET_MAX      INT_LIMIT(loff_t)
953 #define OFFT_OFFSET_MAX INT_LIMIT(off_t)
954 #endif
955 
956 #include <linux/fcntl.h>
957 
958 extern void send_sigio(struct fown_struct *fown, int fd, int band);
959 
960 #ifdef CONFIG_FILE_LOCKING
961 extern int fcntl_getlk(struct file *, unsigned int, struct flock __user *);
962 extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
963                         struct flock __user *);
964 
965 #if BITS_PER_LONG == 32
966 extern int fcntl_getlk64(struct file *, unsigned int, struct flock64 __user *);
967 extern int fcntl_setlk64(unsigned int, struct file *, unsigned int,
968                         struct flock64 __user *);
969 #endif
970 
971 extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
972 extern int fcntl_getlease(struct file *filp);
973 
974 /* fs/locks.c */
975 void locks_free_lock(struct file_lock *fl);
976 extern void locks_init_lock(struct file_lock *);
977 extern struct file_lock * locks_alloc_lock(void);
978 extern void locks_copy_lock(struct file_lock *, struct file_lock *);
979 extern void locks_copy_conflock(struct file_lock *, struct file_lock *);
980 extern void locks_remove_posix(struct file *, fl_owner_t);
981 extern void locks_remove_file(struct file *);
982 extern void locks_release_private(struct file_lock *);
983 extern void posix_test_lock(struct file *, struct file_lock *);
984 extern int posix_lock_file(struct file *, struct file_lock *, struct file_lock *);
985 extern int posix_lock_file_wait(struct file *, struct file_lock *);
986 extern int posix_unblock_lock(struct file_lock *);
987 extern int vfs_test_lock(struct file *, struct file_lock *);
988 extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
989 extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
990 extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
991 extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
992 extern void lease_get_mtime(struct inode *, struct timespec *time);
993 extern int generic_setlease(struct file *, long, struct file_lock **, void **priv);
994 extern int vfs_setlease(struct file *, long, struct file_lock **, void **);
995 extern int lease_modify(struct file_lock **, int, struct list_head *);
996 #else /* !CONFIG_FILE_LOCKING */
997 static inline int fcntl_getlk(struct file *file, unsigned int cmd,
998                               struct flock __user *user)
999 {
1000         return -EINVAL;
1001 }
1002 
1003 static inline int fcntl_setlk(unsigned int fd, struct file *file,
1004                               unsigned int cmd, struct flock __user *user)
1005 {
1006         return -EACCES;
1007 }
1008 
1009 #if BITS_PER_LONG == 32
1010 static inline int fcntl_getlk64(struct file *file, unsigned int cmd,
1011                                 struct flock64 __user *user)
1012 {
1013         return -EINVAL;
1014 }
1015 
1016 static inline int fcntl_setlk64(unsigned int fd, struct file *file,
1017                                 unsigned int cmd, struct flock64 __user *user)
1018 {
1019         return -EACCES;
1020 }
1021 #endif
1022 static inline int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1023 {
1024         return -EINVAL;
1025 }
1026 
1027 static inline int fcntl_getlease(struct file *filp)
1028 {
1029         return F_UNLCK;
1030 }
1031 
1032 static inline void locks_init_lock(struct file_lock *fl)
1033 {
1034         return;
1035 }
1036 
1037 static inline void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
1038 {
1039         return;
1040 }
1041 
1042 static inline void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
1043 {
1044         return;
1045 }
1046 
1047 static inline void locks_remove_posix(struct file *filp, fl_owner_t owner)
1048 {
1049         return;
1050 }
1051 
1052 static inline void locks_remove_file(struct file *filp)
1053 {
1054         return;
1055 }
1056 
1057 static inline void posix_test_lock(struct file *filp, struct file_lock *fl)
1058 {
1059         return;
1060 }
1061 
1062 static inline int posix_lock_file(struct file *filp, struct file_lock *fl,
1063                                   struct file_lock *conflock)
1064 {
1065         return -ENOLCK;
1066 }
1067 
1068 static inline int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
1069 {
1070         return -ENOLCK;
1071 }
1072 
1073 static inline int posix_unblock_lock(struct file_lock *waiter)
1074 {
1075         return -ENOENT;
1076 }
1077 
1078 static inline int vfs_test_lock(struct file *filp, struct file_lock *fl)
1079 {
1080         return 0;
1081 }
1082 
1083 static inline int vfs_lock_file(struct file *filp, unsigned int cmd,
1084                                 struct file_lock *fl, struct file_lock *conf)
1085 {
1086         return -ENOLCK;
1087 }
1088 
1089 static inline int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
1090 {
1091         return 0;
1092 }
1093 
1094 static inline int flock_lock_file_wait(struct file *filp,
1095                                        struct file_lock *request)
1096 {
1097         return -ENOLCK;
1098 }
1099 
1100 static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1101 {
1102         return 0;
1103 }
1104 
1105 static inline void lease_get_mtime(struct inode *inode, struct timespec *time)
1106 {
1107         return;
1108 }
1109 
1110 static inline int generic_setlease(struct file *filp, long arg,
1111                                     struct file_lock **flp, void **priv)
1112 {
1113         return -EINVAL;
1114 }
1115 
1116 static inline int vfs_setlease(struct file *filp, long arg,
1117                                struct file_lock **lease, void **priv)
1118 {
1119         return -EINVAL;
1120 }
1121 
1122 static inline int lease_modify(struct file_lock **before, int arg,
1123                                struct list_head *dispose)
1124 {
1125         return -EINVAL;
1126 }
1127 #endif /* !CONFIG_FILE_LOCKING */
1128 
1129 
1130 struct fasync_struct {
1131         spinlock_t              fa_lock;
1132         int                     magic;
1133         int                     fa_fd;
1134         struct fasync_struct    *fa_next; /* singly linked list */
1135         struct file             *fa_file;
1136         struct rcu_head         fa_rcu;
1137 };
1138 
1139 #define FASYNC_MAGIC 0x4601
1140 
1141 /* SMP safe fasync helpers: */
1142 extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
1143 extern struct fasync_struct *fasync_insert_entry(int, struct file *, struct fasync_struct **, struct fasync_struct *);
1144 extern int fasync_remove_entry(struct file *, struct fasync_struct **);
1145 extern struct fasync_struct *fasync_alloc(void);
1146 extern void fasync_free(struct fasync_struct *);
1147 
1148 /* can be called from interrupts */
1149 extern void kill_fasync(struct fasync_struct **, int, int);
1150 
1151 extern void __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
1152 extern void f_setown(struct file *filp, unsigned long arg, int force);
1153 extern void f_delown(struct file *filp);
1154 extern pid_t f_getown(struct file *filp);
1155 extern int send_sigurg(struct fown_struct *fown);
1156 
1157 struct mm_struct;
1158 
1159 /*
1160  *      Umount options
1161  */
1162 
1163 #define MNT_FORCE       0x00000001      /* Attempt to forcibily umount */
1164 #define MNT_DETACH      0x00000002      /* Just detach from the tree */
1165 #define MNT_EXPIRE      0x00000004      /* Mark for expiry */
1166 #define UMOUNT_NOFOLLOW 0x00000008      /* Don't follow symlink on umount */
1167 #define UMOUNT_UNUSED   0x80000000      /* Flag guaranteed to be unused */
1168 
1169 extern struct list_head super_blocks;
1170 extern spinlock_t sb_lock;
1171 
1172 /* Possible states of 'frozen' field */
1173 enum {
1174         SB_UNFROZEN = 0,                /* FS is unfrozen */
1175         SB_FREEZE_WRITE = 1,            /* Writes, dir ops, ioctls frozen */
1176         SB_FREEZE_PAGEFAULT = 2,        /* Page faults stopped as well */
1177         SB_FREEZE_FS = 3,               /* For internal FS use (e.g. to stop
1178                                          * internal threads if needed) */
1179         SB_FREEZE_COMPLETE = 4,         /* ->freeze_fs finished successfully */
1180 };
1181 
1182 #define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
1183 
1184 struct sb_writers {
1185         /* Counters for counting writers at each level */
1186         struct percpu_counter   counter[SB_FREEZE_LEVELS];
1187         wait_queue_head_t       wait;           /* queue for waiting for
1188                                                    writers / faults to finish */
1189         int                     frozen;         /* Is sb frozen? */
1190         wait_queue_head_t       wait_unfrozen;  /* queue for waiting for
1191                                                    sb to be thawed */
1192 #ifdef CONFIG_DEBUG_LOCK_ALLOC
1193         struct lockdep_map      lock_map[SB_FREEZE_LEVELS];
1194 #endif
1195 };
1196 
1197 struct super_block {
1198         struct list_head        s_list;         /* Keep this first */
1199         dev_t                   s_dev;          /* search index; _not_ kdev_t */
1200         unsigned char           s_blocksize_bits;
1201         unsigned long           s_blocksize;
1202         loff_t                  s_maxbytes;     /* Max file size */
1203         struct file_system_type *s_type;
1204         const struct super_operations   *s_op;
1205         const struct dquot_operations   *dq_op;
1206         const struct quotactl_ops       *s_qcop;
1207         const struct export_operations *s_export_op;
1208         unsigned long           s_flags;
1209         unsigned long           s_magic;
1210         struct dentry           *s_root;
1211         struct rw_semaphore     s_umount;
1212         int                     s_count;
1213         atomic_t                s_active;
1214 #ifdef CONFIG_SECURITY
1215         void                    *s_security;
1216 #endif
1217         const struct xattr_handler **s_xattr;
1218 
1219         struct list_head        s_inodes;       /* all inodes */
1220         struct hlist_bl_head    s_anon;         /* anonymous dentries for (nfs) exporting */
1221         struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
1222         struct block_device     *s_bdev;
1223         struct backing_dev_info *s_bdi;
1224         struct mtd_info         *s_mtd;
1225         struct hlist_node       s_instances;
1226         struct quota_info       s_dquot;        /* Diskquota specific options */
1227 
1228         struct sb_writers       s_writers;
1229 
1230         char s_id[32];                          /* Informational name */
1231         u8 s_uuid[16];                          /* UUID */
1232 
1233         void                    *s_fs_info;     /* Filesystem private info */
1234         unsigned int            s_max_links;
1235         fmode_t                 s_mode;
1236 
1237         /* Granularity of c/m/atime in ns.
1238            Cannot be worse than a second */
1239         u32                s_time_gran;
1240 
1241         /*
1242          * The next field is for VFS *only*. No filesystems have any business
1243          * even looking at it. You had been warned.
1244          */
1245         struct mutex s_vfs_rename_mutex;        /* Kludge */
1246 
1247         /*
1248          * Filesystem subtype.  If non-empty the filesystem type field
1249          * in /proc/mounts will be "type.subtype"
1250          */
1251         char *s_subtype;
1252 
1253         /*
1254          * Saved mount options for lazy filesystems using
1255          * generic_show_options()
1256          */
1257         char __rcu *s_options;
1258         const struct dentry_operations *s_d_op; /* default d_op for dentries */
1259 
1260         /*
1261          * Saved pool identifier for cleancache (-1 means none)
1262          */
1263         int cleancache_poolid;
1264 
1265         struct shrinker s_shrink;       /* per-sb shrinker handle */
1266 
1267         /* Number of inodes with nlink == 0 but still referenced */
1268         atomic_long_t s_remove_count;
1269 
1270         /* Being remounted read-only */
1271         int s_readonly_remount;
1272 
1273         /* AIO completions deferred from interrupt context */
1274         struct workqueue_struct *s_dio_done_wq;
1275         struct hlist_head s_pins;
1276 
1277         /*
1278          * Keep the lru lists last in the structure so they always sit on their
1279          * own individual cachelines.
1280          */
1281         struct list_lru         s_dentry_lru ____cacheline_aligned_in_smp;
1282         struct list_lru         s_inode_lru ____cacheline_aligned_in_smp;
1283         struct rcu_head         rcu;
1284 
1285         /*
1286          * Indicates how deep in a filesystem stack this SB is
1287          */
1288         int s_stack_depth;
1289 };
1290 
1291 extern struct timespec current_fs_time(struct super_block *sb);
1292 
1293 /*
1294  * Snapshotting support.
1295  */
1296 
1297 void __sb_end_write(struct super_block *sb, int level);
1298 int __sb_start_write(struct super_block *sb, int level, bool wait);
1299 
1300 /**
1301  * sb_end_write - drop write access to a superblock
1302  * @sb: the super we wrote to
1303  *
1304  * Decrement number of writers to the filesystem. Wake up possible waiters
1305  * wanting to freeze the filesystem.
1306  */
1307 static inline void sb_end_write(struct super_block *sb)
1308 {
1309         __sb_end_write(sb, SB_FREEZE_WRITE);
1310 }
1311 
1312 /**
1313  * sb_end_pagefault - drop write access to a superblock from a page fault
1314  * @sb: the super we wrote to
1315  *
1316  * Decrement number of processes handling write page fault to the filesystem.
1317  * Wake up possible waiters wanting to freeze the filesystem.
1318  */
1319 static inline void sb_end_pagefault(struct super_block *sb)
1320 {
1321         __sb_end_write(sb, SB_FREEZE_PAGEFAULT);
1322 }
1323 
1324 /**
1325  * sb_end_intwrite - drop write access to a superblock for internal fs purposes
1326  * @sb: the super we wrote to
1327  *
1328  * Decrement fs-internal number of writers to the filesystem.  Wake up possible
1329  * waiters wanting to freeze the filesystem.
1330  */
1331 static inline void sb_end_intwrite(struct super_block *sb)
1332 {
1333         __sb_end_write(sb, SB_FREEZE_FS);
1334 }
1335 
1336 /**
1337  * sb_start_write - get write access to a superblock
1338  * @sb: the super we write to
1339  *
1340  * When a process wants to write data or metadata to a file system (i.e. dirty
1341  * a page or an inode), it should embed the operation in a sb_start_write() -
1342  * sb_end_write() pair to get exclusion against file system freezing. This
1343  * function increments number of writers preventing freezing. If the file
1344  * system is already frozen, the function waits until the file system is
1345  * thawed.
1346  *
1347  * Since freeze protection behaves as a lock, users have to preserve
1348  * ordering of freeze protection and other filesystem locks. Generally,
1349  * freeze protection should be the outermost lock. In particular, we have:
1350  *
1351  * sb_start_write
1352  *   -> i_mutex                 (write path, truncate, directory ops, ...)
1353  *   -> s_umount                (freeze_super, thaw_super)
1354  */
1355 static inline void sb_start_write(struct super_block *sb)
1356 {
1357         __sb_start_write(sb, SB_FREEZE_WRITE, true);
1358 }
1359 
1360 static inline int sb_start_write_trylock(struct super_block *sb)
1361 {
1362         return __sb_start_write(sb, SB_FREEZE_WRITE, false);
1363 }
1364 
1365 /**
1366  * sb_start_pagefault - get write access to a superblock from a page fault
1367  * @sb: the super we write to
1368  *
1369  * When a process starts handling write page fault, it should embed the
1370  * operation into sb_start_pagefault() - sb_end_pagefault() pair to get
1371  * exclusion against file system freezing. This is needed since the page fault
1372  * is going to dirty a page. This function increments number of running page
1373  * faults preventing freezing. If the file system is already frozen, the
1374  * function waits until the file system is thawed.
1375  *
1376  * Since page fault freeze protection behaves as a lock, users have to preserve
1377  * ordering of freeze protection and other filesystem locks. It is advised to
1378  * put sb_start_pagefault() close to mmap_sem in lock ordering. Page fault
1379  * handling code implies lock dependency:
1380  *
1381  * mmap_sem
1382  *   -> sb_start_pagefault
1383  */
1384 static inline void sb_start_pagefault(struct super_block *sb)
1385 {
1386         __sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
1387 }
1388 
1389 /*
1390  * sb_start_intwrite - get write access to a superblock for internal fs purposes
1391  * @sb: the super we write to
1392  *
1393  * This is the third level of protection against filesystem freezing. It is
1394  * free for use by a filesystem. The only requirement is that it must rank
1395  * below sb_start_pagefault.
1396  *
1397  * For example filesystem can call sb_start_intwrite() when starting a
1398  * transaction which somewhat eases handling of freezing for internal sources
1399  * of filesystem changes (internal fs threads, discarding preallocation on file
1400  * close, etc.).
1401  */
1402 static inline void sb_start_intwrite(struct super_block *sb)
1403 {
1404         __sb_start_write(sb, SB_FREEZE_FS, true);
1405 }
1406 
1407 
1408 extern bool inode_owner_or_capable(const struct inode *inode);
1409 
1410 /*
1411  * VFS helper functions..
1412  */
1413 extern int vfs_create(struct inode *, struct dentry *, umode_t, bool);
1414 extern int vfs_mkdir(struct inode *, struct dentry *, umode_t);
1415 extern int vfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
1416 extern int vfs_symlink(struct inode *, struct dentry *, const char *);
1417 extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
1418 extern int vfs_rmdir(struct inode *, struct dentry *);
1419 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
1420 extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
1421 extern int vfs_whiteout(struct inode *, struct dentry *);
1422 
1423 /*
1424  * VFS dentry helper functions.
1425  */
1426 extern void dentry_unhash(struct dentry *dentry);
1427 
1428 /*
1429  * VFS file helper functions.
1430  */
1431 extern void inode_init_owner(struct inode *inode, const struct inode *dir,
1432                         umode_t mode);
1433 /*
1434  * VFS FS_IOC_FIEMAP helper definitions.
1435  */
1436 struct fiemap_extent_info {
1437         unsigned int fi_flags;          /* Flags as passed from user */
1438         unsigned int fi_extents_mapped; /* Number of mapped extents */
1439         unsigned int fi_extents_max;    /* Size of fiemap_extent array */
1440         struct fiemap_extent __user *fi_extents_start; /* Start of
1441                                                         fiemap_extent array */
1442 };
1443 int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
1444                             u64 phys, u64 len, u32 flags);
1445 int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
1446 
1447 /*
1448  * File types
1449  *
1450  * NOTE! These match bits 12..15 of stat.st_mode
1451  * (ie "(i_mode >> 12) & 15").
1452  */
1453 #define DT_UNKNOWN      0
1454 #define DT_FIFO         1
1455 #define DT_CHR          2
1456 #define DT_DIR          4
1457 #define DT_BLK          6
1458 #define DT_REG          8
1459 #define DT_LNK          10
1460 #define DT_SOCK         12
1461 #define DT_WHT          14
1462 
1463 /*
1464  * This is the "filldir" function type, used by readdir() to let
1465  * the kernel specify what kind of dirent layout it wants to have.
1466  * This allows the kernel to read directories into kernel space or
1467  * to have different dirent layouts depending on the binary type.
1468  */
1469 typedef int (*filldir_t)(void *, const char *, int, loff_t, u64, unsigned);
1470 struct dir_context {
1471         const filldir_t actor;
1472         loff_t pos;
1473 };
1474 
1475 struct block_device_operations;
1476 
1477 /* These macros are for out of kernel modules to test that
1478  * the kernel supports the unlocked_ioctl and compat_ioctl
1479  * fields in struct file_operations. */
1480 #define HAVE_COMPAT_IOCTL 1
1481 #define HAVE_UNLOCKED_IOCTL 1
1482 
1483 struct iov_iter;
1484 
1485 struct file_operations {
1486         struct module *owner;
1487         loff_t (*llseek) (struct file *, loff_t, int);
1488         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
1489         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
1490         ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
1491         ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
1492         ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
1493         ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
1494         int (*iterate) (struct file *, struct dir_context *);
1495         unsigned int (*poll) (struct file *, struct poll_table_struct *);
1496         long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
1497         long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
1498         int (*mmap) (struct file *, struct vm_area_struct *);
1499         int (*open) (struct inode *, struct file *);
1500         int (*flush) (struct file *, fl_owner_t id);
1501         int (*release) (struct inode *, struct file *);
1502         int (*fsync) (struct file *, loff_t, loff_t, int datasync);
1503         int (*aio_fsync) (struct kiocb *, int datasync);
1504         int (*fasync) (int, struct file *, int);
1505         int (*lock) (struct file *, int, struct file_lock *);
1506         ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
1507         unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1508         int (*check_flags)(int);
1509         int (*flock) (struct file *, int, struct file_lock *);
1510         ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
1511         ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
1512         int (*setlease)(struct file *, long, struct file_lock **, void **);
1513         long (*fallocate)(struct file *file, int mode, loff_t offset,
1514                           loff_t len);
1515         int (*show_fdinfo)(struct seq_file *m, struct file *f);
1516 };
1517 
1518 struct inode_operations {
1519         struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
1520         void * (*follow_link) (struct dentry *, struct nameidata *);
1521         int (*permission) (struct inode *, int);
1522         struct posix_acl * (*get_acl)(struct inode *, int);
1523 
1524         int (*readlink) (struct dentry *, char __user *,int);
1525         void (*put_link) (struct dentry *, struct nameidata *, void *);
1526 
1527         int (*create) (struct inode *,struct dentry *, umode_t, bool);
1528         int (*link) (struct dentry *,struct inode *,struct dentry *);
1529         int (*unlink) (struct inode *,struct dentry *);
1530         int (*symlink) (struct inode *,struct dentry *,const char *);
1531         int (*mkdir) (struct inode *,struct dentry *,umode_t);
1532         int (*rmdir) (struct inode *,struct dentry *);
1533         int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
1534         int (*rename) (struct inode *, struct dentry *,
1535                         struct inode *, struct dentry *);
1536         int (*rename2) (struct inode *, struct dentry *,
1537                         struct inode *, struct dentry *, unsigned int);
1538         int (*setattr) (struct dentry *, struct iattr *);
1539         int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
1540         int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
1541         ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
1542         ssize_t (*listxattr) (struct dentry *, char *, size_t);
1543         int (*removexattr) (struct dentry *, const char *);
1544         int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
1545                       u64 len);
1546         int (*update_time)(struct inode *, struct timespec *, int);
1547         int (*atomic_open)(struct inode *, struct dentry *,
1548                            struct file *, unsigned open_flag,
1549                            umode_t create_mode, int *opened);
1550         int (*tmpfile) (struct inode *, struct dentry *, umode_t);
1551         int (*set_acl)(struct inode *, struct posix_acl *, int);
1552 
1553         /* WARNING: probably going away soon, do not use! */
1554 } ____cacheline_aligned;
1555 
1556 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
1557                               unsigned long nr_segs, unsigned long fast_segs,
1558                               struct iovec *fast_pointer,
1559                               struct iovec **ret_pointer);
1560 
1561 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
1562 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
1563 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
1564                 unsigned long, loff_t *);
1565 extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
1566                 unsigned long, loff_t *);
1567 
1568 struct super_operations {
1569         struct inode *(*alloc_inode)(struct super_block *sb);
1570         void (*destroy_inode)(struct inode *);
1571 
1572         void (*dirty_inode) (struct inode *, int flags);
1573         int (*write_inode) (struct inode *, struct writeback_control *wbc);
1574         int (*drop_inode) (struct inode *);
1575         void (*evict_inode) (struct inode *);
1576         void (*put_super) (struct super_block *);
1577         int (*sync_fs)(struct super_block *sb, int wait);
1578         int (*freeze_fs) (struct super_block *);
1579         int (*unfreeze_fs) (struct super_block *);
1580         int (*statfs) (struct dentry *, struct kstatfs *);
1581         int (*remount_fs) (struct super_block *, int *, char *);
1582         void (*umount_begin) (struct super_block *);
1583 
1584         int (*show_options)(struct seq_file *, struct dentry *);
1585         int (*show_devname)(struct seq_file *, struct dentry *);
1586         int (*show_path)(struct seq_file *, struct dentry *);
1587         int (*show_stats)(struct seq_file *, struct dentry *);
1588 #ifdef CONFIG_QUOTA
1589         ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
1590         ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
1591 #endif
1592         int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
1593         long (*nr_cached_objects)(struct super_block *, int);
1594         long (*free_cached_objects)(struct super_block *, long, int);
1595 };
1596 
1597 /*
1598  * Inode flags - they have no relation to superblock flags now
1599  */
1600 #define S_SYNC          1       /* Writes are synced at once */
1601 #define S_NOATIME       2       /* Do not update access times */
1602 #define S_APPEND        4       /* Append-only file */
1603 #define S_IMMUTABLE     8       /* Immutable file */
1604 #define S_DEAD          16      /* removed, but still open directory */
1605 #define S_NOQUOTA       32      /* Inode is not counted to quota */
1606 #define S_DIRSYNC       64      /* Directory modifications are synchronous */
1607 #define S_NOCMTIME      128     /* Do not update file c/mtime */
1608 #define S_SWAPFILE      256     /* Do not truncate: swapon got its bmaps */
1609 #define S_PRIVATE       512     /* Inode is fs-internal */
1610 #define S_IMA           1024    /* Inode has an associated IMA struct */
1611 #define S_AUTOMOUNT     2048    /* Automount/referral quasi-directory */
1612 #define S_NOSEC         4096    /* no suid or xattr security attributes */
1613 
1614 /*
1615  * Note that nosuid etc flags are inode-specific: setting some file-system
1616  * flags just means all the inodes inherit those flags by default. It might be
1617  * possible to override it selectively if you really wanted to with some
1618  * ioctl() that is not currently implemented.
1619  *
1620  * Exception: MS_RDONLY is always applied to the entire file system.
1621  *
1622  * Unfortunately, it is possible to change a filesystems flags with it mounted
1623  * with files in use.  This means that all of the inodes will not have their
1624  * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
1625  * flags, so these have to be checked separately. -- rmk@arm.uk.linux.org
1626  */
1627 #define __IS_FLG(inode, flg)    ((inode)->i_sb->s_flags & (flg))
1628 
1629 #define IS_RDONLY(inode)        ((inode)->i_sb->s_flags & MS_RDONLY)
1630 #define IS_SYNC(inode)          (__IS_FLG(inode, MS_SYNCHRONOUS) || \
1631                                         ((inode)->i_flags & S_SYNC))
1632 #define IS_DIRSYNC(inode)       (__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
1633                                         ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
1634 #define IS_MANDLOCK(inode)      __IS_FLG(inode, MS_MANDLOCK)
1635 #define IS_NOATIME(inode)       __IS_FLG(inode, MS_RDONLY|MS_NOATIME)
1636 #define IS_I_VERSION(inode)     __IS_FLG(inode, MS_I_VERSION)
1637 
1638 #define IS_NOQUOTA(inode)       ((inode)->i_flags & S_NOQUOTA)
1639 #define IS_APPEND(inode)        ((inode)->i_flags & S_APPEND)
1640 #define IS_IMMUTABLE(inode)     ((inode)->i_flags & S_IMMUTABLE)
1641 #define IS_POSIXACL(inode)      __IS_FLG(inode, MS_POSIXACL)
1642 
1643 #define IS_DEADDIR(inode)       ((inode)->i_flags & S_DEAD)
1644 #define IS_NOCMTIME(inode)      ((inode)->i_flags & S_NOCMTIME)
1645 #define IS_SWAPFILE(inode)      ((inode)->i_flags & S_SWAPFILE)
1646 #define IS_PRIVATE(inode)       ((inode)->i_flags & S_PRIVATE)
1647 #define IS_IMA(inode)           ((inode)->i_flags & S_IMA)
1648 #define IS_AUTOMOUNT(inode)     ((inode)->i_flags & S_AUTOMOUNT)
1649 #define IS_NOSEC(inode)         ((inode)->i_flags & S_NOSEC)
1650 
1651 #define IS_WHITEOUT(inode)      (S_ISCHR(inode->i_mode) && \
1652                                  (inode)->i_rdev == WHITEOUT_DEV)
1653 
1654 /*
1655  * Inode state bits.  Protected by inode->i_lock
1656  *
1657  * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
1658  * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
1659  *
1660  * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
1661  * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
1662  * various stages of removing an inode.
1663  *
1664  * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
1665  *
1666  * I_DIRTY_SYNC         Inode is dirty, but doesn't have to be written on
1667  *                      fdatasync().  i_atime is the usual cause.
1668  * I_DIRTY_DATASYNC     Data-related inode changes pending. We keep track of
1669  *                      these changes separately from I_DIRTY_SYNC so that we
1670  *                      don't have to write inode on fdatasync() when only
1671  *                      mtime has changed in it.
1672  * I_DIRTY_PAGES        Inode has dirty pages.  Inode itself may be clean.
1673  * I_NEW                Serves as both a mutex and completion notification.
1674  *                      New inodes set I_NEW.  If two processes both create
1675  *                      the same inode, one of them will release its inode and
1676  *                      wait for I_NEW to be released before returning.
1677  *                      Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
1678  *                      also cause waiting on I_NEW, without I_NEW actually
1679  *                      being set.  find_inode() uses this to prevent returning
1680  *                      nearly-dead inodes.
1681  * I_WILL_FREE          Must be set when calling write_inode_now() if i_count
1682  *                      is zero.  I_FREEING must be set when I_WILL_FREE is
1683  *                      cleared.
1684  * I_FREEING            Set when inode is about to be freed but still has dirty
1685  *                      pages or buffers attached or the inode itself is still
1686  *                      dirty.
1687  * I_CLEAR              Added by clear_inode().  In this state the inode is
1688  *                      clean and can be destroyed.  Inode keeps I_FREEING.
1689  *
1690  *                      Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
1691  *                      prohibited for many purposes.  iget() must wait for
1692  *                      the inode to be completely released, then create it
1693  *                      anew.  Other functions will just ignore such inodes,
1694  *                      if appropriate.  I_NEW is used for waiting.
1695  *
1696  * I_SYNC               Writeback of inode is running. The bit is set during
1697  *                      data writeback, and cleared with a wakeup on the bit
1698  *                      address once it is done. The bit is also used to pin
1699  *                      the inode in memory for flusher thread.
1700  *
1701  * I_REFERENCED         Marks the inode as recently references on the LRU list.
1702  *
1703  * I_DIO_WAKEUP         Never set.  Only used as a key for wait_on_bit().
1704  *
1705  * Q: What is the difference between I_WILL_FREE and I_FREEING?
1706  */
1707 #define I_DIRTY_SYNC            (1 << 0)
1708 #define I_DIRTY_DATASYNC        (1 << 1)
1709 #define I_DIRTY_PAGES           (1 << 2)
1710 #define __I_NEW                 3
1711 #define I_NEW                   (1 << __I_NEW)
1712 #define I_WILL_FREE             (1 << 4)
1713 #define I_FREEING               (1 << 5)
1714 #define I_CLEAR                 (1 << 6)
1715 #define __I_SYNC                7
1716 #define I_SYNC                  (1 << __I_SYNC)
1717 #define I_REFERENCED            (1 << 8)
1718 #define __I_DIO_WAKEUP          9
1719 #define I_DIO_WAKEUP            (1 << I_DIO_WAKEUP)
1720 #define I_LINKABLE              (1 << 10)
1721 
1722 #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)
1723 
1724 extern void __mark_inode_dirty(struct inode *, int);
1725 static inline void mark_inode_dirty(struct inode *inode)
1726 {
1727         __mark_inode_dirty(inode, I_DIRTY);
1728 }
1729 
1730 static inline void mark_inode_dirty_sync(struct inode *inode)
1731 {
1732         __mark_inode_dirty(inode, I_DIRTY_SYNC);
1733 }
1734 
1735 extern void inc_nlink(struct inode *inode);
1736 extern void drop_nlink(struct inode *inode);
1737 extern void clear_nlink(struct inode *inode);
1738 extern void set_nlink(struct inode *inode, unsigned int nlink);
1739 
1740 static inline void inode_inc_link_count(struct inode *inode)
1741 {
1742         inc_nlink(inode);
1743         mark_inode_dirty(inode);
1744 }
1745 
1746 static inline void inode_dec_link_count(struct inode *inode)
1747 {
1748         drop_nlink(inode);
1749         mark_inode_dirty(inode);
1750 }
1751 
1752 /**
1753  * inode_inc_iversion - increments i_version
1754  * @inode: inode that need to be updated
1755  *
1756  * Every time the inode is modified, the i_version field will be incremented.
1757  * The filesystem has to be mounted with i_version flag
1758  */
1759 
1760 static inline void inode_inc_iversion(struct inode *inode)
1761 {
1762        spin_lock(&inode->i_lock);
1763        inode->i_version++;
1764        spin_unlock(&inode->i_lock);
1765 }
1766 
1767 enum file_time_flags {
1768         S_ATIME = 1,
1769         S_MTIME = 2,
1770         S_CTIME = 4,
1771         S_VERSION = 8,
1772 };
1773 
1774 extern void touch_atime(const struct path *);
1775 static inline void file_accessed(struct file *file)
1776 {
1777         if (!(file->f_flags & O_NOATIME))
1778                 touch_atime(&file->f_path);
1779 }
1780 
1781 int sync_inode(struct inode *inode, struct writeback_control *wbc);
1782 int sync_inode_metadata(struct inode *inode, int wait);
1783 
1784 struct file_system_type {
1785         const char *name;
1786         int fs_flags;
1787 #define FS_REQUIRES_DEV         1 
1788 #define FS_BINARY_MOUNTDATA     2
1789 #define FS_HAS_SUBTYPE          4
1790 #define FS_USERNS_MOUNT         8       /* Can be mounted by userns root */
1791 #define FS_USERNS_DEV_MOUNT     16 /* A userns mount does not imply MNT_NODEV */
1792 #define FS_USERNS_VISIBLE       32      /* FS must already be visible */
1793 #define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
1794         struct dentry *(*mount) (struct file_system_type *, int,
1795                        const char *, void *);
1796         void (*kill_sb) (struct super_block *);
1797         struct module *owner;
1798         struct file_system_type * next;
1799         struct hlist_head fs_supers;
1800 
1801         struct lock_class_key s_lock_key;
1802         struct lock_class_key s_umount_key;
1803         struct lock_class_key s_vfs_rename_key;
1804         struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];
1805 
1806         struct lock_class_key i_lock_key;
1807         struct lock_class_key i_mutex_key;
1808         struct lock_class_key i_mutex_dir_key;
1809 };
1810 
1811 #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)
1812 
1813 extern struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
1814         void *data, int (*fill_super)(struct super_block *, void *, int));
1815 extern struct dentry *mount_bdev(struct file_system_type *fs_type,
1816         int flags, const char *dev_name, void *data,
1817         int (*fill_super)(struct super_block *, void *, int));
1818 extern struct dentry *mount_single(struct file_system_type *fs_type,
1819         int flags, void *data,
1820         int (*fill_super)(struct super_block *, void *, int));
1821 extern struct dentry *mount_nodev(struct file_system_type *fs_type,
1822         int flags, void *data,
1823         int (*fill_super)(struct super_block *, void *, int));
1824 extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
1825 void generic_shutdown_super(struct super_block *sb);
1826 void kill_block_super(struct super_block *sb);
1827 void kill_anon_super(struct super_block *sb);
1828 void kill_litter_super(struct super_block *sb);
1829 void deactivate_super(struct super_block *sb);
1830 void deactivate_locked_super(struct super_block *sb);
1831 int set_anon_super(struct super_block *s, void *data);
1832 int get_anon_bdev(dev_t *);
1833 void free_anon_bdev(dev_t);
1834 struct super_block *sget(struct file_system_type *type,
1835                         int (*test)(struct super_block *,void *),
1836                         int (*set)(struct super_block *,void *),
1837                         int flags, void *data);
1838 extern struct dentry *mount_pseudo(struct file_system_type *, char *,
1839         const struct super_operations *ops,
1840         const struct dentry_operations *dops,
1841         unsigned long);
1842 
1843 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
1844 #define fops_get(fops) \
1845         (((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
1846 #define fops_put(fops) \
1847         do { if (fops) module_put((fops)->owner); } while(0)
1848 /*
1849  * This one is to be used *ONLY* from ->open() instances.
1850  * fops must be non-NULL, pinned down *and* module dependencies
1851  * should be sufficient to pin the caller down as well.
1852  */
1853 #define replace_fops(f, fops) \
1854         do {    \
1855                 struct file *__file = (f); \
1856                 fops_put(__file->f_op); \
1857                 BUG_ON(!(__file->f_op = (fops))); \
1858         } while(0)
1859 
1860 extern int register_filesystem(struct file_system_type *);
1861 extern int unregister_filesystem(struct file_system_type *);
1862 extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
1863 #define kern_mount(type) kern_mount_data(type, NULL)
1864 extern void kern_unmount(struct vfsmount *mnt);
1865 extern int may_umount_tree(struct vfsmount *);
1866 extern int may_umount(struct vfsmount *);
1867 extern long do_mount(const char *, const char __user *,
1868                      const char *, unsigned long, void *);
1869 extern struct vfsmount *collect_mounts(struct path *);
1870 extern void drop_collected_mounts(struct vfsmount *);
1871 extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
1872                           struct vfsmount *);
1873 extern int vfs_statfs(struct path *, struct kstatfs *);
1874 extern int user_statfs(const char __user *, struct kstatfs *);
1875 extern int fd_statfs(int, struct kstatfs *);
1876 extern int vfs_ustat(dev_t, struct kstatfs *);
1877 extern int freeze_super(struct super_block *super);
1878 extern int thaw_super(struct super_block *super);
1879 extern bool our_mnt(struct vfsmount *mnt);
1880 
1881 extern int current_umask(void);
1882 
1883 extern void ihold(struct inode * inode);
1884 extern void iput(struct inode *);
1885 
1886 static inline struct inode *file_inode(const struct file *f)
1887 {
1888         return f->f_inode;
1889 }
1890 
1891 /* /sys/fs */
1892 extern struct kobject *fs_kobj;
1893 
1894 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
1895 
1896 #define FLOCK_VERIFY_READ  1
1897 #define FLOCK_VERIFY_WRITE 2
1898 
1899 #ifdef CONFIG_FILE_LOCKING
1900 extern int locks_mandatory_locked(struct file *);
1901 extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);
1902 
1903 /*
1904  * Candidates for mandatory locking have the setgid bit set
1905  * but no group execute bit -  an otherwise meaningless combination.
1906  */
1907 
1908 static inline int __mandatory_lock(struct inode *ino)
1909 {
1910         return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
1911 }
1912 
1913 /*
1914  * ... and these candidates should be on MS_MANDLOCK mounted fs,
1915  * otherwise these will be advisory locks
1916  */
1917 
1918 static inline int mandatory_lock(struct inode *ino)
1919 {
1920         return IS_MANDLOCK(ino) && __mandatory_lock(ino);
1921 }
1922 
1923 static inline int locks_verify_locked(struct file *file)
1924 {
1925         if (mandatory_lock(file_inode(file)))
1926                 return locks_mandatory_locked(file);
1927         return 0;
1928 }
1929 
1930 static inline int locks_verify_truncate(struct inode *inode,
1931                                     struct file *filp,
1932                                     loff_t size)
1933 {
1934         if (inode->i_flock && mandatory_lock(inode))
1935                 return locks_mandatory_area(
1936                         FLOCK_VERIFY_WRITE, inode, filp,
1937                         size < inode->i_size ? size : inode->i_size,
1938                         (size < inode->i_size ? inode->i_size - size
1939                          : size - inode->i_size)
1940                 );
1941         return 0;
1942 }
1943 
1944 static inline int break_lease(struct inode *inode, unsigned int mode)
1945 {
1946         /*
1947          * Since this check is lockless, we must ensure that any refcounts
1948          * taken are done before checking i_flctx->flc_lease. Otherwise, we
1949          * could end up racing with tasks trying to set a new lease on this
1950          * file.
1951          */
1952         smp_mb();
1953         if (inode->i_flock)
1954                 return __break_lease(inode, mode, FL_LEASE);
1955         return 0;
1956 }
1957 
1958 static inline int break_deleg(struct inode *inode, unsigned int mode)
1959 {
1960         /*
1961          * Since this check is lockless, we must ensure that any refcounts
1962          * taken are done before checking i_flctx->flc_lease. Otherwise, we
1963          * could end up racing with tasks trying to set a new lease on this
1964          * file.
1965          */
1966         smp_mb();
1967         if (inode->i_flock)
1968                 return __break_lease(inode, mode, FL_DELEG);
1969         return 0;
1970 }
1971 
1972 static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
1973 {
1974         int ret;
1975 
1976         ret = break_deleg(inode, O_WRONLY|O_NONBLOCK);
1977         if (ret == -EWOULDBLOCK && delegated_inode) {
1978                 *delegated_inode = inode;
1979                 ihold(inode);
1980         }
1981         return ret;
1982 }
1983 
1984 static inline int break_deleg_wait(struct inode **delegated_inode)
1985 {
1986         int ret;
1987 
1988         ret = break_deleg(*delegated_inode, O_WRONLY);
1989         iput(*delegated_inode);
1990         *delegated_inode = NULL;
1991         return ret;
1992 }
1993 
1994 #else /* !CONFIG_FILE_LOCKING */
1995 static inline int locks_mandatory_locked(struct file *file)
1996 {
1997         return 0;
1998 }
1999 
2000 static inline int locks_mandatory_area(int rw, struct inode *inode,
2001                                        struct file *filp, loff_t offset,
2002                                        size_t count)
2003 {
2004         return 0;
2005 }
2006 
2007 static inline int __mandatory_lock(struct inode *inode)
2008 {
2009         return 0;
2010 }
2011 
2012 static inline int mandatory_lock(struct inode *inode)
2013 {
2014         return 0;
2015 }
2016 
2017 static inline int locks_verify_locked(struct file *file)
2018 {
2019         return 0;
2020 }
2021 
2022 static inline int locks_verify_truncate(struct inode *inode, struct file *filp,
2023                                         size_t size)
2024 {
2025         return 0;
2026 }
2027 
2028 static inline int break_lease(struct inode *inode, unsigned int mode)
2029 {
2030         return 0;
2031 }
2032 
2033 static inline int break_deleg(struct inode *inode, unsigned int mode)
2034 {
2035         return 0;
2036 }
2037 
2038 static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
2039 {
2040         return 0;
2041 }
2042 
2043 static inline int break_deleg_wait(struct inode **delegated_inode)
2044 {
2045         BUG();
2046         return 0;
2047 }
2048 
2049 #endif /* CONFIG_FILE_LOCKING */
2050 
2051 /* fs/open.c */
2052 struct audit_names;
2053 struct filename {
2054         const char              *name;  /* pointer to actual string */
2055         const __user char       *uptr;  /* original userland pointer */
2056         struct audit_names      *aname;
2057         bool                    separate; /* should "name" be freed? */
2058 };
2059 
2060 extern long vfs_truncate(struct path *, loff_t);
2061 extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
2062                        struct file *filp);
2063 extern int do_fallocate(struct file *file, int mode, loff_t offset,
2064                         loff_t len);
2065 extern long do_sys_open(int dfd, const char __user *filename, int flags,
2066                         umode_t mode);
2067 extern struct file *file_open_name(struct filename *, int, umode_t);
2068 extern struct file *filp_open(const char *, int, umode_t);
2069 extern struct file *file_open_root(struct dentry *, struct vfsmount *,
2070                                    const char *, int, umode_t);
2071 extern struct file * dentry_open(const struct path *, int, const struct cred *);
2072 extern int filp_close(struct file *, fl_owner_t id);
2073 
2074 extern struct filename *getname(const char __user *);
2075 extern struct filename *getname_kernel(const char *);
2076 
2077 enum {
2078         FILE_CREATED = 1,
2079         FILE_OPENED = 2
2080 };
2081 extern int finish_open(struct file *file, struct dentry *dentry,
2082                         int (*open)(struct inode *, struct file *),
2083                         int *opened);
2084 extern int finish_no_open(struct file *file, struct dentry *dentry);
2085 
2086 /* fs/ioctl.c */
2087 
2088 extern int ioctl_preallocate(struct file *filp, void __user *argp);
2089 
2090 /* fs/dcache.c */
2091 extern void __init vfs_caches_init_early(void);
2092 extern void __init vfs_caches_init(unsigned long);
2093 
2094 extern struct kmem_cache *names_cachep;
2095 
2096 extern void final_putname(struct filename *name);
2097 
2098 #define __getname()             kmem_cache_alloc(names_cachep, GFP_KERNEL)
2099 #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
2100 #ifndef CONFIG_AUDITSYSCALL
2101 #define putname(name)           final_putname(name)
2102 #else
2103 extern void putname(struct filename *name);
2104 #endif
2105 
2106 #ifdef CONFIG_BLOCK
2107 extern int register_blkdev(unsigned int, const char *);
2108 extern void unregister_blkdev(unsigned int, const char *);
2109 extern struct block_device *bdget(dev_t);
2110 extern struct block_device *bdgrab(struct block_device *bdev);
2111 extern void bd_set_size(struct block_device *, loff_t size);
2112 extern void bd_forget(struct inode *inode);
2113 extern void bdput(struct block_device *);
2114 extern void invalidate_bdev(struct block_device *);
2115 extern void iterate_bdevs(void (*)(struct block_device *, void *), void *);
2116 extern int sync_blockdev(struct block_device *bdev);
2117 extern void kill_bdev(struct block_device *);
2118 extern struct super_block *freeze_bdev(struct block_device *);
2119 extern void emergency_thaw_all(void);
2120 extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
2121 extern int fsync_bdev(struct block_device *);
2122 extern int sb_is_blkdev_sb(struct super_block *sb);
2123 #else
2124 static inline void bd_forget(struct inode *inode) {}
2125 static inline int sync_blockdev(struct block_device *bdev) { return 0; }
2126 static inline void kill_bdev(struct block_device *bdev) {}
2127 static inline void invalidate_bdev(struct block_device *bdev) {}
2128 
2129 static inline struct super_block *freeze_bdev(struct block_device *sb)
2130 {
2131         return NULL;
2132 }
2133 
2134 static inline int thaw_bdev(struct block_device *bdev, struct super_block *sb)
2135 {
2136         return 0;
2137 }
2138 
2139 static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void *arg)
2140 {
2141 }
2142 
2143 static inline int sb_is_blkdev_sb(struct super_block *sb)
2144 {
2145         return 0;
2146 }
2147 #endif
2148 extern int sync_filesystem(struct super_block *);
2149 extern const struct file_operations def_blk_fops;
2150 extern const struct file_operations def_chr_fops;
2151 extern const struct file_operations bad_sock_fops;
2152 #ifdef CONFIG_BLOCK
2153 extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
2154 extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
2155 extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
2156 extern int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder);
2157 extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
2158                                                void *holder);
2159 extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
2160                                               void *holder);
2161 extern void blkdev_put(struct block_device *bdev, fmode_t mode);
2162 #ifdef CONFIG_SYSFS
2163 extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
2164 extern void bd_unlink_disk_holder(struct block_device *bdev,
2165                                   struct gendisk *disk);
2166 #else
2167 static inline int bd_link_disk_holder(struct block_device *bdev,
2168                                       struct gendisk *disk)
2169 {
2170         return 0;
2171 }
2172 static inline void bd_unlink_disk_holder(struct block_device *bdev,
2173                                          struct gendisk *disk)
2174 {
2175 }
2176 #endif
2177 #endif
2178 
2179 /* fs/char_dev.c */
2180 #define CHRDEV_MAJOR_HASH_SIZE  255
2181 extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
2182 extern int register_chrdev_region(dev_t, unsigned, const char *);
2183 extern int __register_chrdev(unsigned int major, unsigned int baseminor,
2184                              unsigned int count, const char *name,
2185                              const struct file_operations *fops);
2186 extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
2187                                 unsigned int count, const char *name);
2188 extern void unregister_chrdev_region(dev_t, unsigned);
2189 extern void chrdev_show(struct seq_file *,off_t);
2190 
2191 static inline int register_chrdev(unsigned int major, const char *name,
2192                                   const struct file_operations *fops)
2193 {
2194         return __register_chrdev(major, 0, 256, name, fops);
2195 }
2196 
2197 static inline void unregister_chrdev(unsigned int major, const char *name)
2198 {
2199         __unregister_chrdev(major, 0, 256, name);
2200 }
2201 
2202 /* fs/block_dev.c */
2203 #define BDEVNAME_SIZE   32      /* Largest string for a blockdev identifier */
2204 #define BDEVT_SIZE      10      /* Largest string for MAJ:MIN for blkdev */
2205 
2206 #ifdef CONFIG_BLOCK
2207 #define BLKDEV_MAJOR_HASH_SIZE  255
2208 extern const char *__bdevname(dev_t, char *buffer);
2209 extern const char *bdevname(struct block_device *bdev, char *buffer);
2210 extern struct block_device *lookup_bdev(const char *);
2211 extern void blkdev_show(struct seq_file *,off_t);
2212 
2213 #else
2214 #define BLKDEV_MAJOR_HASH_SIZE  0
2215 #endif
2216 
2217 extern void init_special_inode(struct inode *, umode_t, dev_t);
2218 
2219 /* Invalid inode operations -- fs/bad_inode.c */
2220 extern void make_bad_inode(struct inode *);
2221 extern int is_bad_inode(struct inode *);
2222 
2223 #ifdef CONFIG_BLOCK
2224 /*
2225  * return READ, READA, or WRITE
2226  */
2227 #define bio_rw(bio)             ((bio)->bi_rw & (RW_MASK | RWA_MASK))
2228 
2229 /*
2230  * return data direction, READ or WRITE
2231  */
2232 #define bio_data_dir(bio)       ((bio)->bi_rw & 1)
2233 
2234 extern void check_disk_size_change(struct gendisk *disk,
2235                                    struct block_device *bdev);
2236 extern int revalidate_disk(struct gendisk *);
2237 extern int check_disk_change(struct block_device *);
2238 extern int __invalidate_device(struct block_device *, bool);
2239 extern int invalidate_partition(struct gendisk *, int);
2240 #endif
2241 unsigned long invalidate_mapping_pages(struct address_space *mapping,
2242                                         pgoff_t start, pgoff_t end);
2243 
2244 static inline void invalidate_remote_inode(struct inode *inode)
2245 {
2246         if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
2247             S_ISLNK(inode->i_mode))
2248                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
2249 }
2250 extern int invalidate_inode_pages2(struct address_space *mapping);
2251 extern int invalidate_inode_pages2_range(struct address_space *mapping,
2252                                          pgoff_t start, pgoff_t end);
2253 extern int write_inode_now(struct inode *, int);
2254 extern int filemap_fdatawrite(struct address_space *);
2255 extern int filemap_flush(struct address_space *);
2256 extern int filemap_fdatawait(struct address_space *);
2257 extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
2258                                    loff_t lend);
2259 extern int filemap_write_and_wait(struct address_space *mapping);
2260 extern int filemap_write_and_wait_range(struct address_space *mapping,
2261                                         loff_t lstart, loff_t lend);
2262 extern int __filemap_fdatawrite_range(struct address_space *mapping,
2263                                 loff_t start, loff_t end, int sync_mode);
2264 extern int filemap_fdatawrite_range(struct address_space *mapping,
2265                                 loff_t start, loff_t end);
2266 
2267 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
2268                            int datasync);
2269 extern int vfs_fsync(struct file *file, int datasync);
2270 static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
2271 {
2272         if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
2273                 return 0;
2274         return vfs_fsync_range(file, pos, pos + count - 1,
2275                                (file->f_flags & __O_SYNC) ? 0 : 1);
2276 }
2277 extern void emergency_sync(void);
2278 extern void emergency_remount(void);
2279 #ifdef CONFIG_BLOCK
2280 extern sector_t bmap(struct inode *, sector_t);
2281 #endif
2282 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
2283 extern int inode_permission(struct inode *, int);
2284 extern int __inode_permission(struct inode *, int);
2285 extern int generic_permission(struct inode *, int);
2286 extern int __check_sticky(struct inode *dir, struct inode *inode);
2287 
2288 static inline bool execute_ok(struct inode *inode)
2289 {
2290         return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
2291 }
2292 
2293 static inline void file_start_write(struct file *file)
2294 {
2295         if (!S_ISREG(file_inode(file)->i_mode))
2296                 return;
2297         __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
2298 }
2299 
2300 static inline bool file_start_write_trylock(struct file *file)
2301 {
2302         if (!S_ISREG(file_inode(file)->i_mode))
2303                 return true;
2304         return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false);
2305 }
2306 
2307 static inline void file_end_write(struct file *file)
2308 {
2309         if (!S_ISREG(file_inode(file)->i_mode))
2310                 return;
2311         __sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE);
2312 }
2313 
2314 /*
2315  * get_write_access() gets write permission for a file.
2316  * put_write_access() releases this write permission.
2317  * This is used for regular files.
2318  * We cannot support write (and maybe mmap read-write shared) accesses and
2319  * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
2320  * can have the following values:
2321  * 0: no writers, no VM_DENYWRITE mappings
2322  * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
2323  * > 0: (i_writecount) users are writing to the file.
2324  *
2325  * Normally we operate on that counter with atomic_{inc,dec} and it's safe
2326  * except for the cases where we don't hold i_writecount yet. Then we need to
2327  * use {get,deny}_write_access() - these functions check the sign and refuse
2328  * to do the change if sign is wrong.
2329  */
2330 static inline int get_write_access(struct inode *inode)
2331 {
2332         return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
2333 }
2334 static inline int deny_write_access(struct file *file)
2335 {
2336         struct inode *inode = file_inode(file);
2337         return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
2338 }
2339 static inline void put_write_access(struct inode * inode)
2340 {
2341         atomic_dec(&inode->i_writecount);
2342 }
2343 static inline void allow_write_access(struct file *file)
2344 {
2345         if (file)
2346                 atomic_inc(&file_inode(file)->i_writecount);
2347 }
2348 static inline bool inode_is_open_for_write(const struct inode *inode)
2349 {
2350         return atomic_read(&inode->i_writecount) > 0;
2351 }
2352 
2353 #ifdef CONFIG_IMA
2354 static inline void i_readcount_dec(struct inode *inode)
2355 {
2356         BUG_ON(!atomic_read(&inode->i_readcount));
2357         atomic_dec(&inode->i_readcount);
2358 }
2359 static inline void i_readcount_inc(struct inode *inode)
2360 {
2361         atomic_inc(&inode->i_readcount);
2362 }
2363 #else
2364 static inline void i_readcount_dec(struct inode *inode)
2365 {
2366         return;
2367 }
2368 static inline void i_readcount_inc(struct inode *inode)
2369 {
2370         return;
2371 }
2372 #endif
2373 extern int do_pipe_flags(int *, int);
2374 
2375 extern int kernel_read(struct file *, loff_t, char *, unsigned long);
2376 extern ssize_t kernel_write(struct file *, const char *, size_t, loff_t);
2377 extern ssize_t __kernel_write(struct file *, const char *, size_t, loff_t *);
2378 extern struct file * open_exec(const char *);
2379  
2380 /* fs/dcache.c -- generic fs support functions */
2381 extern int is_subdir(struct dentry *, struct dentry *);
2382 extern int path_is_under(struct path *, struct path *);
2383 
2384 #include <linux/err.h>
2385 
2386 /* needed for stackable file system support */
2387 extern loff_t default_llseek(struct file *file, loff_t offset, int whence);
2388 
2389 extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence);
2390 
2391 extern int inode_init_always(struct super_block *, struct inode *);
2392 extern void inode_init_once(struct inode *);
2393 extern void address_space_init_once(struct address_space *mapping);
2394 extern struct inode * igrab(struct inode *);
2395 extern ino_t iunique(struct super_block *, ino_t);
2396 extern int inode_needs_sync(struct inode *inode);
2397 extern int generic_delete_inode(struct inode *inode);
2398 static inline int generic_drop_inode(struct inode *inode)
2399 {
2400         return !inode->i_nlink || inode_unhashed(inode);
2401 }
2402 
2403 extern struct inode *ilookup5_nowait(struct super_block *sb,
2404                 unsigned long hashval, int (*test)(struct inode *, void *),
2405                 void *data);
2406 extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
2407                 int (*test)(struct inode *, void *), void *data);
2408 extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
2409 
2410 extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
2411 extern struct inode * iget_locked(struct super_block *, unsigned long);
2412 extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
2413 extern int insert_inode_locked(struct inode *);
2414 #ifdef CONFIG_DEBUG_LOCK_ALLOC
2415 extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
2416 #else
2417 static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
2418 #endif
2419 extern void unlock_new_inode(struct inode *);
2420 extern unsigned int get_next_ino(void);
2421 
2422 extern void __iget(struct inode * inode);
2423 extern void iget_failed(struct inode *);
2424 extern void clear_inode(struct inode *);
2425 extern void __destroy_inode(struct inode *);
2426 extern struct inode *new_inode_pseudo(struct super_block *sb);
2427 extern struct inode *new_inode(struct super_block *sb);
2428 extern void free_inode_nonrcu(struct inode *inode);
2429 extern int should_remove_suid(struct dentry *);
2430 extern int file_remove_suid(struct file *);
2431 
2432 extern void __insert_inode_hash(struct inode *, unsigned long hashval);
2433 static inline void insert_inode_hash(struct inode *inode)
2434 {
2435         __insert_inode_hash(inode, inode->i_ino);
2436 }
2437 
2438 extern void __remove_inode_hash(struct inode *);
2439 static inline void remove_inode_hash(struct inode *inode)
2440 {
2441         if (!inode_unhashed(inode))
2442                 __remove_inode_hash(inode);
2443 }
2444 
2445 extern void inode_sb_list_add(struct inode *inode);
2446 
2447 #ifdef CONFIG_BLOCK
2448 extern void submit_bio(int, struct bio *);
2449 extern int bdev_read_only(struct block_device *);
2450 #endif
2451 extern int set_blocksize(struct block_device *, int);
2452 extern int sb_set_blocksize(struct super_block *, int);
2453 extern int sb_min_blocksize(struct super_block *, int);
2454 
2455 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
2456 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
2457 extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
2458                 unsigned long size, pgoff_t pgoff);
2459 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
2460 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
2461 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
2462 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
2463 extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *, loff_t);
2464 extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
2465 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
2466 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
2467 extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
2468 extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
2469 
2470 /* fs/block_dev.c */
2471 extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
2472 extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);
2473 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
2474                         int datasync);
2475 extern void block_sync_page(struct page *page);
2476 
2477 /* fs/splice.c */
2478 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
2479                 struct pipe_inode_info *, size_t, unsigned int);
2480 extern ssize_t default_file_splice_read(struct file *, loff_t *,
2481                 struct pipe_inode_info *, size_t, unsigned int);
2482 extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
2483                 struct file *, loff_t *, size_t, unsigned int);
2484 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
2485                 struct file *out, loff_t *, size_t len, unsigned int flags);
2486 extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
2487                 loff_t *opos, size_t len, unsigned int flags);
2488 
2489 
2490 extern void
2491 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
2492 extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
2493 extern loff_t no_llseek(struct file *file, loff_t offset, int whence);
2494 extern loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize);
2495 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
2496 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
2497                 int whence, loff_t maxsize, loff_t eof);
2498 extern loff_t fixed_size_llseek(struct file *file, loff_t offset,
2499                 int whence, loff_t size);
2500 extern int generic_file_open(struct inode * inode, struct file * filp);
2501 extern int nonseekable_open(struct inode * inode, struct file * filp);
2502 
2503 #ifdef CONFIG_FS_XIP
2504 extern ssize_t xip_file_read(struct file *filp, char __user *buf, size_t len,
2505                              loff_t *ppos);
2506 extern int xip_file_mmap(struct file * file, struct vm_area_struct * vma);
2507 extern ssize_t xip_file_write(struct file *filp, const char __user *buf,
2508                               size_t len, loff_t *ppos);
2509 extern int xip_truncate_page(struct address_space *mapping, loff_t from);
2510 #else
2511 static inline int xip_truncate_page(struct address_space *mapping, loff_t from)
2512 {
2513         return 0;
2514 }
2515 #endif
2516 
2517 #ifdef CONFIG_BLOCK
2518 typedef void (dio_submit_t)(int rw, struct bio *bio, struct inode *inode,
2519                             loff_t file_offset);
2520 
2521 enum {
2522         /* need locking between buffered and direct access */
2523         DIO_LOCKING     = 0x01,
2524 
2525         /* filesystem does not support filling holes */
2526         DIO_SKIP_HOLES  = 0x02,
2527 
2528         /* filesystem can handle aio writes beyond i_size */
2529         DIO_ASYNC_EXTEND = 0x04,
2530 };
2531 
2532 void dio_end_io(struct bio *bio, int error);
2533 
2534 ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
2535         struct block_device *bdev, struct iov_iter *iter, loff_t offset,
2536         get_block_t get_block, dio_iodone_t end_io,
2537         dio_submit_t submit_io, int flags);
2538 
2539 static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
2540                 struct inode *inode, struct iov_iter *iter, loff_t offset,
2541                 get_block_t get_block)
2542 {
2543         return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iter,
2544                                     offset, get_block, NULL, NULL,
2545                                     DIO_LOCKING | DIO_SKIP_HOLES);
2546 }
2547 #endif
2548 
2549 void inode_dio_wait(struct inode *inode);
2550 void inode_dio_done(struct inode *inode);
2551 
2552 extern void inode_set_flags(struct inode *inode, unsigned int flags,
2553                             unsigned int mask);
2554 
2555 extern const struct file_operations generic_ro_fops;
2556 
2557 #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
2558 
2559 extern int readlink_copy(char __user *, int, const char *);
2560 extern int page_readlink(struct dentry *, char __user *, int);
2561 extern void *page_follow_link_light(struct dentry *, struct nameidata *);
2562 extern void page_put_link(struct dentry *, struct nameidata *, void *);
2563 extern int __page_symlink(struct inode *inode, const char *symname, int len,
2564                 int nofs);
2565 extern int page_symlink(struct inode *inode, const char *symname, int len);
2566 extern const struct inode_operations page_symlink_inode_operations;
2567 extern void kfree_put_link(struct dentry *, struct nameidata *, void *);
2568 extern int generic_readlink(struct dentry *, char __user *, int);
2569 extern void generic_fillattr(struct inode *, struct kstat *);
2570 int vfs_getattr_nosec(struct path *path, struct kstat *stat);
2571 extern int vfs_getattr(struct path *, struct kstat *);
2572 void __inode_add_bytes(struct inode *inode, loff_t bytes);
2573 void inode_add_bytes(struct inode *inode, loff_t bytes);
2574 void __inode_sub_bytes(struct inode *inode, loff_t bytes);
2575 void inode_sub_bytes(struct inode *inode, loff_t bytes);
2576 loff_t inode_get_bytes(struct inode *inode);
2577 void inode_set_bytes(struct inode *inode, loff_t bytes);
2578 
2579 extern int vfs_readdir(struct file *, filldir_t, void *);
2580 extern int iterate_dir(struct file *, struct dir_context *);
2581 
2582 extern int vfs_stat(const char __user *, struct kstat *);
2583 extern int vfs_lstat(const char __user *, struct kstat *);
2584 extern int vfs_fstat(unsigned int, struct kstat *);
2585 extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
2586 
2587 extern int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
2588                     unsigned long arg);
2589 extern int __generic_block_fiemap(struct inode *inode,
2590                                   struct fiemap_extent_info *fieinfo,
2591                                   loff_t start, loff_t len,
2592                                   get_block_t *get_block);
2593 extern int generic_block_fiemap(struct inode *inode,
2594                                 struct fiemap_extent_info *fieinfo, u64 start,
2595                                 u64 len, get_block_t *get_block);
2596 
2597 extern void get_filesystem(struct file_system_type *fs);
2598 extern void put_filesystem(struct file_system_type *fs);
2599 extern struct file_system_type *get_fs_type(const char *name);
2600 extern struct super_block *get_super(struct block_device *);
2601 extern struct super_block *get_super_thawed(struct block_device *);
2602 extern struct super_block *get_active_super(struct block_device *bdev);
2603 extern void drop_super(struct super_block *sb);
2604 extern void iterate_supers(void (*)(struct super_block *, void *), void *);
2605 extern void iterate_supers_type(struct file_system_type *,
2606                                 void (*)(struct super_block *, void *), void *);
2607 
2608 extern int dcache_dir_open(struct inode *, struct file *);
2609 extern int dcache_dir_close(struct inode *, struct file *);
2610 extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
2611 extern int dcache_readdir(struct file *, struct dir_context *);
2612 extern int simple_setattr(struct dentry *, struct iattr *);
2613 extern int simple_getattr(struct vfsmount *, struct dentry *, struct kstat *);
2614 extern int simple_statfs(struct dentry *, struct kstatfs *);
2615 extern int simple_open(struct inode *inode, struct file *file);
2616 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
2617 extern int simple_unlink(struct inode *, struct dentry *);
2618 extern int simple_rmdir(struct inode *, struct dentry *);
2619 extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
2620 extern int noop_fsync(struct file *, loff_t, loff_t, int);
2621 extern int simple_empty(struct dentry *);
2622 extern int simple_readpage(struct file *file, struct page *page);
2623 extern int simple_write_begin(struct file *file, struct address_space *mapping,
2624                         loff_t pos, unsigned len, unsigned flags,
2625                         struct page **pagep, void **fsdata);
2626 extern int simple_write_end(struct file *file, struct address_space *mapping,
2627                         loff_t pos, unsigned len, unsigned copied,
2628                         struct page *page, void *fsdata);
2629 extern int always_delete_dentry(const struct dentry *);
2630 extern struct inode *alloc_anon_inode(struct super_block *);
2631 extern int simple_nosetlease(struct file *, long, struct file_lock **, void **);
2632 extern const struct dentry_operations simple_dentry_operations;
2633 
2634 extern struct dentry *simple_lookup(struct inode *, struct dentry *, unsigned int flags);
2635 extern ssize_t generic_read_dir(struct file *, char __user *, size_t, loff_t *);
2636 extern const struct file_operations simple_dir_operations;
2637 extern const struct inode_operations simple_dir_inode_operations;
2638 struct tree_descr { char *name; const struct file_operations *ops; int mode; };
2639 struct dentry *d_alloc_name(struct dentry *, const char *);
2640 extern int simple_fill_super(struct super_block *, unsigned long, struct tree_descr *);
2641 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
2642 extern void simple_release_fs(struct vfsmount **mount, int *count);
2643 
2644 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
2645                         loff_t *ppos, const void *from, size_t available);
2646 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
2647                 const void __user *from, size_t count);
2648 
2649 extern int __generic_file_fsync(struct file *, loff_t, loff_t, int);
2650 extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
2651 
2652 extern int generic_check_addressable(unsigned, u64);
2653 
2654 #ifdef CONFIG_MIGRATION
2655 extern int buffer_migrate_page(struct address_space *,
2656                                 struct page *, struct page *,
2657                                 enum migrate_mode);
2658 #else
2659 #define buffer_migrate_page NULL
2660 #endif
2661 
2662 extern int inode_change_ok(const struct inode *, struct iattr *);
2663 extern int inode_newsize_ok(const struct inode *, loff_t offset);
2664 extern void setattr_copy(struct inode *inode, const struct iattr *attr);
2665 
2666 extern int file_update_time(struct file *file);
2667 
2668 extern int generic_show_options(struct seq_file *m, struct dentry *root);
2669 extern void save_mount_options(struct super_block *sb, char *options);
2670 extern void replace_mount_options(struct super_block *sb, char *options);
2671 
2672 static inline ino_t parent_ino(struct dentry *dentry)
2673 {
2674         ino_t res;
2675 
2676         /*
2677          * Don't strictly need d_lock here? If the parent ino could change
2678          * then surely we'd have a deeper race in the caller?
2679          */
2680         spin_lock(&dentry->d_lock);
2681         res = dentry->d_parent->d_inode->i_ino;
2682         spin_unlock(&dentry->d_lock);
2683         return res;
2684 }
2685 
2686 /* Transaction based IO helpers */
2687 
2688 /*
2689  * An argresp is stored in an allocated page and holds the
2690  * size of the argument or response, along with its content
2691  */
2692 struct simple_transaction_argresp {
2693         ssize_t size;
2694         char data[0];
2695 };
2696 
2697 #define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))
2698 
2699 char *simple_transaction_get(struct file *file, const char __user *buf,
2700                                 size_t size);
2701 ssize_t simple_transaction_read(struct file *file, char __user *buf,
2702                                 size_t size, loff_t *pos);
2703 int simple_transaction_release(struct inode *inode, struct file *file);
2704 
2705 void simple_transaction_set(struct file *file, size_t n);
2706 
2707 /*
2708  * simple attribute files
2709  *
2710  * These attributes behave similar to those in sysfs:
2711  *
2712  * Writing to an attribute immediately sets a value, an open file can be
2713  * written to multiple times.
2714  *
2715  * Reading from an attribute creates a buffer from the value that might get
2716  * read with multiple read calls. When the attribute has been read
2717  * completely, no further read calls are possible until the file is opened
2718  * again.
2719  *
2720  * All attributes contain a text representation of a numeric value
2721  * that are accessed with the get() and set() functions.
2722  */
2723 #define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)            \
2724 static int __fops ## _open(struct inode *inode, struct file *file)      \
2725 {                                                                       \
2726         __simple_attr_check_format(__fmt, 0ull);                        \
2727         return simple_attr_open(inode, file, __get, __set, __fmt);      \
2728 }                                                                       \
2729 static const struct file_operations __fops = {                          \
2730         .owner   = THIS_MODULE,                                         \
2731         .open    = __fops ## _open,                                     \
2732         .release = simple_attr_release,                                 \
2733         .read    = simple_attr_read,                                    \
2734         .write   = simple_attr_write,                                   \
2735         .llseek  = generic_file_llseek,                                 \
2736 }
2737 
2738 static inline __printf(1, 2)
2739 void __simple_attr_check_format(const char *fmt, ...)
2740 {
2741         /* don't do anything, just let the compiler check the arguments; */
2742 }
2743 
2744 int simple_attr_open(struct inode *inode, struct file *file,
2745                      int (*get)(void *, u64 *), int (*set)(void *, u64),
2746                      const char *fmt);
2747 int simple_attr_release(struct inode *inode, struct file *file);
2748 ssize_t simple_attr_read(struct file *file, char __user *buf,
2749                          size_t len, loff_t *ppos);
2750 ssize_t simple_attr_write(struct file *file, const char __user *buf,
2751                           size_t len, loff_t *ppos);
2752 
2753 struct ctl_table;
2754 int proc_nr_files(struct ctl_table *table, int write,
2755                   void __user *buffer, size_t *lenp, loff_t *ppos);
2756 int proc_nr_dentry(struct ctl_table *table, int write,
2757                   void __user *buffer, size_t *lenp, loff_t *ppos);
2758 int proc_nr_inodes(struct ctl_table *table, int write,
2759                    void __user *buffer, size_t *lenp, loff_t *ppos);
2760 int __init get_filesystem_list(char *buf);
2761 
2762 #define __FMODE_EXEC            ((__force int) FMODE_EXEC)
2763 #define __FMODE_NONOTIFY        ((__force int) FMODE_NONOTIFY)
2764 
2765 #define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
2766 #define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
2767                                             (flag & __FMODE_NONOTIFY)))
2768 
2769 static inline int is_sxid(umode_t mode)
2770 {
2771         return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
2772 }
2773 
2774 static inline int check_sticky(struct inode *dir, struct inode *inode)
2775 {
2776         if (!(dir->i_mode & S_ISVTX))
2777                 return 0;
2778 
2779         return __check_sticky(dir, inode);
2780 }
2781 
2782 static inline void inode_has_no_xattr(struct inode *inode)
2783 {
2784         if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))
2785                 inode->i_flags |= S_NOSEC;
2786 }
2787 
2788 static inline bool dir_emit(struct dir_context *ctx,
2789                             const char *name, int namelen,
2790                             u64 ino, unsigned type)
2791 {
2792         return ctx->actor(ctx, name, namelen, ctx->pos, ino, type) == 0;
2793 }
2794 static inline bool dir_emit_dot(struct file *file, struct dir_context *ctx)
2795 {
2796         return ctx->actor(ctx, ".", 1, ctx->pos,
2797                           file->f_path.dentry->d_inode->i_ino, DT_DIR) == 0;
2798 }
2799 static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
2800 {
2801         return ctx->actor(ctx, "..", 2, ctx->pos,
2802                           parent_ino(file->f_path.dentry), DT_DIR) == 0;
2803 }
2804 static inline bool dir_emit_dots(struct file *file, struct dir_context *ctx)
2805 {
2806         if (ctx->pos == 0) {
2807                 if (!dir_emit_dot(file, ctx))
2808                         return false;
2809                 ctx->pos = 1;
2810         }
2811         if (ctx->pos == 1) {
2812                 if (!dir_emit_dotdot(file, ctx))
2813                         return false;
2814                 ctx->pos = 2;
2815         }
2816         return true;
2817 }
2818 static inline bool dir_relax(struct inode *inode)
2819 {
2820         mutex_unlock(&inode->i_mutex);
2821         mutex_lock(&inode->i_mutex);
2822         return !IS_DEADDIR(inode);
2823 }
2824 
2825 #endif /* _LINUX_FS_H */
2826 

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