xref: /linux-6.15/include/linux/fs.h (revision 776cfebb)
1 #ifndef _LINUX_FS_H
2 #define _LINUX_FS_H
3 
4 /*
5  * This file has definitions for some important file table
6  * structures etc.
7  */
8 
9 #include <linux/config.h>
10 #include <linux/limits.h>
11 #include <linux/ioctl.h>
12 
13 /*
14  * It's silly to have NR_OPEN bigger than NR_FILE, but you can change
15  * the file limit at runtime and only root can increase the per-process
16  * nr_file rlimit, so it's safe to set up a ridiculously high absolute
17  * upper limit on files-per-process.
18  *
19  * Some programs (notably those using select()) may have to be
20  * recompiled to take full advantage of the new limits..
21  */
22 
23 /* Fixed constants first: */
24 #undef NR_OPEN
25 #define NR_OPEN (1024*1024)	/* Absolute upper limit on fd num */
26 #define INR_OPEN 1024		/* Initial setting for nfile rlimits */
27 
28 #define BLOCK_SIZE_BITS 10
29 #define BLOCK_SIZE (1<<BLOCK_SIZE_BITS)
30 
31 /* And dynamically-tunable limits and defaults: */
32 struct files_stat_struct {
33 	int nr_files;		/* read only */
34 	int nr_free_files;	/* read only */
35 	int max_files;		/* tunable */
36 };
37 extern struct files_stat_struct files_stat;
38 
39 struct inodes_stat_t {
40 	int nr_inodes;
41 	int nr_unused;
42 	int dummy[5];
43 };
44 extern struct inodes_stat_t inodes_stat;
45 
46 extern int leases_enable, lease_break_time;
47 
48 #ifdef CONFIG_DNOTIFY
49 extern int dir_notify_enable;
50 #endif
51 
52 #define NR_FILE  8192	/* this can well be larger on a larger system */
53 
54 #define MAY_EXEC 1
55 #define MAY_WRITE 2
56 #define MAY_READ 4
57 #define MAY_APPEND 8
58 
59 #define FMODE_READ 1
60 #define FMODE_WRITE 2
61 
62 /* Internal kernel extensions */
63 #define FMODE_LSEEK	4
64 #define FMODE_PREAD	8
65 #define FMODE_PWRITE	FMODE_PREAD	/* These go hand in hand */
66 
67 #define RW_MASK		1
68 #define RWA_MASK	2
69 #define READ 0
70 #define WRITE 1
71 #define READA 2		/* read-ahead  - don't block if no resources */
72 #define SPECIAL 4	/* For non-blockdevice requests in request queue */
73 #define READ_SYNC	(READ | (1 << BIO_RW_SYNC))
74 #define WRITE_SYNC	(WRITE | (1 << BIO_RW_SYNC))
75 #define WRITE_BARRIER	((1 << BIO_RW) | (1 << BIO_RW_BARRIER))
76 
77 #define SEL_IN		1
78 #define SEL_OUT		2
79 #define SEL_EX		4
80 
81 /* public flags for file_system_type */
82 #define FS_REQUIRES_DEV 1
83 #define FS_BINARY_MOUNTDATA 2
84 #define FS_REVAL_DOT	16384	/* Check the paths ".", ".." for staleness */
85 #define FS_ODD_RENAME	32768	/* Temporary stuff; will go away as soon
86 				  * as nfs_rename() will be cleaned up
87 				  */
88 /*
89  * These are the fs-independent mount-flags: up to 32 flags are supported
90  */
91 #define MS_RDONLY	 1	/* Mount read-only */
92 #define MS_NOSUID	 2	/* Ignore suid and sgid bits */
93 #define MS_NODEV	 4	/* Disallow access to device special files */
94 #define MS_NOEXEC	 8	/* Disallow program execution */
95 #define MS_SYNCHRONOUS	16	/* Writes are synced at once */
96 #define MS_REMOUNT	32	/* Alter flags of a mounted FS */
97 #define MS_MANDLOCK	64	/* Allow mandatory locks on an FS */
98 #define MS_DIRSYNC	128	/* Directory modifications are synchronous */
99 #define MS_NOATIME	1024	/* Do not update access times. */
100 #define MS_NODIRATIME	2048	/* Do not update directory access times */
101 #define MS_BIND		4096
102 #define MS_MOVE		8192
103 #define MS_REC		16384
104 #define MS_VERBOSE	32768
105 #define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
106 #define MS_ACTIVE	(1<<30)
107 #define MS_NOUSER	(1<<31)
108 
109 /*
110  * Superblock flags that can be altered by MS_REMOUNT
111  */
112 #define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_NOATIME|\
113 			 MS_NODIRATIME)
114 
115 /*
116  * Old magic mount flag and mask
117  */
118 #define MS_MGC_VAL 0xC0ED0000
119 #define MS_MGC_MSK 0xffff0000
120 
121 /* Inode flags - they have nothing to superblock flags now */
122 
123 #define S_SYNC		1	/* Writes are synced at once */
124 #define S_NOATIME	2	/* Do not update access times */
125 #define S_APPEND	4	/* Append-only file */
126 #define S_IMMUTABLE	8	/* Immutable file */
127 #define S_DEAD		16	/* removed, but still open directory */
128 #define S_NOQUOTA	32	/* Inode is not counted to quota */
129 #define S_DIRSYNC	64	/* Directory modifications are synchronous */
130 #define S_NOCMTIME	128	/* Do not update file c/mtime */
131 #define S_SWAPFILE	256	/* Do not truncate: swapon got its bmaps */
132 #define S_PRIVATE	512	/* Inode is fs-internal */
133 
134 /*
135  * Note that nosuid etc flags are inode-specific: setting some file-system
136  * flags just means all the inodes inherit those flags by default. It might be
137  * possible to override it selectively if you really wanted to with some
138  * ioctl() that is not currently implemented.
139  *
140  * Exception: MS_RDONLY is always applied to the entire file system.
141  *
142  * Unfortunately, it is possible to change a filesystems flags with it mounted
143  * with files in use.  This means that all of the inodes will not have their
144  * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
145  * flags, so these have to be checked separately. -- [email protected]
146  */
147 #define __IS_FLG(inode,flg) ((inode)->i_sb->s_flags & (flg))
148 
149 #define IS_RDONLY(inode) ((inode)->i_sb->s_flags & MS_RDONLY)
150 #define IS_SYNC(inode)		(__IS_FLG(inode, MS_SYNCHRONOUS) || \
151 					((inode)->i_flags & S_SYNC))
152 #define IS_DIRSYNC(inode)	(__IS_FLG(inode, MS_SYNCHRONOUS|MS_DIRSYNC) || \
153 					((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
154 #define IS_MANDLOCK(inode)	__IS_FLG(inode, MS_MANDLOCK)
155 
156 #define IS_NOQUOTA(inode)	((inode)->i_flags & S_NOQUOTA)
157 #define IS_APPEND(inode)	((inode)->i_flags & S_APPEND)
158 #define IS_IMMUTABLE(inode)	((inode)->i_flags & S_IMMUTABLE)
159 #define IS_NOATIME(inode)	(__IS_FLG(inode, MS_NOATIME) || ((inode)->i_flags & S_NOATIME))
160 #define IS_NODIRATIME(inode)	__IS_FLG(inode, MS_NODIRATIME)
161 #define IS_POSIXACL(inode)	__IS_FLG(inode, MS_POSIXACL)
162 
163 #define IS_DEADDIR(inode)	((inode)->i_flags & S_DEAD)
164 #define IS_NOCMTIME(inode)	((inode)->i_flags & S_NOCMTIME)
165 #define IS_SWAPFILE(inode)	((inode)->i_flags & S_SWAPFILE)
166 #define IS_PRIVATE(inode)	((inode)->i_flags & S_PRIVATE)
167 
168 /* the read-only stuff doesn't really belong here, but any other place is
169    probably as bad and I don't want to create yet another include file. */
170 
171 #define BLKROSET   _IO(0x12,93)	/* set device read-only (0 = read-write) */
172 #define BLKROGET   _IO(0x12,94)	/* get read-only status (0 = read_write) */
173 #define BLKRRPART  _IO(0x12,95)	/* re-read partition table */
174 #define BLKGETSIZE _IO(0x12,96)	/* return device size /512 (long *arg) */
175 #define BLKFLSBUF  _IO(0x12,97)	/* flush buffer cache */
176 #define BLKRASET   _IO(0x12,98)	/* set read ahead for block device */
177 #define BLKRAGET   _IO(0x12,99)	/* get current read ahead setting */
178 #define BLKFRASET  _IO(0x12,100)/* set filesystem (mm/filemap.c) read-ahead */
179 #define BLKFRAGET  _IO(0x12,101)/* get filesystem (mm/filemap.c) read-ahead */
180 #define BLKSECTSET _IO(0x12,102)/* set max sectors per request (ll_rw_blk.c) */
181 #define BLKSECTGET _IO(0x12,103)/* get max sectors per request (ll_rw_blk.c) */
182 #define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
183 #if 0
184 #define BLKPG      _IO(0x12,105)/* See blkpg.h */
185 
186 /* Some people are morons.  Do not use sizeof! */
187 
188 #define BLKELVGET  _IOR(0x12,106,size_t)/* elevator get */
189 #define BLKELVSET  _IOW(0x12,107,size_t)/* elevator set */
190 /* This was here just to show that the number is taken -
191    probably all these _IO(0x12,*) ioctls should be moved to blkpg.h. */
192 #endif
193 /* A jump here: 108-111 have been used for various private purposes. */
194 #define BLKBSZGET  _IOR(0x12,112,size_t)
195 #define BLKBSZSET  _IOW(0x12,113,size_t)
196 #define BLKGETSIZE64 _IOR(0x12,114,size_t)	/* return device size in bytes (u64 *arg) */
197 
198 #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
199 #define FIBMAP	   _IO(0x00,1)	/* bmap access */
200 #define FIGETBSZ   _IO(0x00,2)	/* get the block size used for bmap */
201 
202 #ifdef __KERNEL__
203 
204 #include <linux/linkage.h>
205 #include <linux/wait.h>
206 #include <linux/types.h>
207 #include <linux/kdev_t.h>
208 #include <linux/dcache.h>
209 #include <linux/stat.h>
210 #include <linux/cache.h>
211 #include <linux/kobject.h>
212 #include <linux/list.h>
213 #include <linux/radix-tree.h>
214 #include <linux/prio_tree.h>
215 #include <linux/init.h>
216 
217 #include <asm/atomic.h>
218 #include <asm/semaphore.h>
219 #include <asm/byteorder.h>
220 
221 struct iovec;
222 struct nameidata;
223 struct pipe_inode_info;
224 struct poll_table_struct;
225 struct kstatfs;
226 struct vm_area_struct;
227 struct vfsmount;
228 
229 /* Used to be a macro which just called the function, now just a function */
230 extern void update_atime (struct inode *);
231 
232 extern void __init inode_init(unsigned long);
233 extern void __init inode_init_early(void);
234 extern void __init mnt_init(unsigned long);
235 extern void __init files_init(unsigned long);
236 
237 struct buffer_head;
238 typedef int (get_block_t)(struct inode *inode, sector_t iblock,
239 			struct buffer_head *bh_result, int create);
240 typedef int (get_blocks_t)(struct inode *inode, sector_t iblock,
241 			unsigned long max_blocks,
242 			struct buffer_head *bh_result, int create);
243 typedef void (dio_iodone_t)(struct inode *inode, loff_t offset,
244 			ssize_t bytes, void *private);
245 
246 /*
247  * Attribute flags.  These should be or-ed together to figure out what
248  * has been changed!
249  */
250 #define ATTR_MODE	1
251 #define ATTR_UID	2
252 #define ATTR_GID	4
253 #define ATTR_SIZE	8
254 #define ATTR_ATIME	16
255 #define ATTR_MTIME	32
256 #define ATTR_CTIME	64
257 #define ATTR_ATIME_SET	128
258 #define ATTR_MTIME_SET	256
259 #define ATTR_FORCE	512	/* Not a change, but a change it */
260 #define ATTR_ATTR_FLAG	1024
261 #define ATTR_KILL_SUID	2048
262 #define ATTR_KILL_SGID	4096
263 
264 /*
265  * This is the Inode Attributes structure, used for notify_change().  It
266  * uses the above definitions as flags, to know which values have changed.
267  * Also, in this manner, a Filesystem can look at only the values it cares
268  * about.  Basically, these are the attributes that the VFS layer can
269  * request to change from the FS layer.
270  *
271  * Derek Atkins <[email protected]> 94-10-20
272  */
273 struct iattr {
274 	unsigned int	ia_valid;
275 	umode_t		ia_mode;
276 	uid_t		ia_uid;
277 	gid_t		ia_gid;
278 	loff_t		ia_size;
279 	struct timespec	ia_atime;
280 	struct timespec	ia_mtime;
281 	struct timespec	ia_ctime;
282 	unsigned int	ia_attr_flags;
283 };
284 
285 /*
286  * This is the inode attributes flag definitions
287  */
288 #define ATTR_FLAG_SYNCRONOUS	1 	/* Syncronous write */
289 #define ATTR_FLAG_NOATIME	2 	/* Don't update atime */
290 #define ATTR_FLAG_APPEND	4 	/* Append-only file */
291 #define ATTR_FLAG_IMMUTABLE	8 	/* Immutable file */
292 #define ATTR_FLAG_NODIRATIME	16 	/* Don't update atime for directory */
293 
294 /*
295  * Includes for diskquotas.
296  */
297 #include <linux/quota.h>
298 
299 /*
300  * oh the beauties of C type declarations.
301  */
302 struct page;
303 struct address_space;
304 struct writeback_control;
305 struct kiocb;
306 
307 struct address_space_operations {
308 	int (*writepage)(struct page *page, struct writeback_control *wbc);
309 	int (*readpage)(struct file *, struct page *);
310 	int (*sync_page)(struct page *);
311 
312 	/* Write back some dirty pages from this mapping. */
313 	int (*writepages)(struct address_space *, struct writeback_control *);
314 
315 	/* Set a page dirty */
316 	int (*set_page_dirty)(struct page *page);
317 
318 	int (*readpages)(struct file *filp, struct address_space *mapping,
319 			struct list_head *pages, unsigned nr_pages);
320 
321 	/*
322 	 * ext3 requires that a successful prepare_write() call be followed
323 	 * by a commit_write() call - they must be balanced
324 	 */
325 	int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
326 	int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
327 	/* Unfortunately this kludge is needed for FIBMAP. Don't use it */
328 	sector_t (*bmap)(struct address_space *, sector_t);
329 	int (*invalidatepage) (struct page *, unsigned long);
330 	int (*releasepage) (struct page *, int);
331 	ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
332 			loff_t offset, unsigned long nr_segs);
333 };
334 
335 struct backing_dev_info;
336 struct address_space {
337 	struct inode		*host;		/* owner: inode, block_device */
338 	struct radix_tree_root	page_tree;	/* radix tree of all pages */
339 	rwlock_t		tree_lock;	/* and rwlock protecting it */
340 	unsigned int		i_mmap_writable;/* count VM_SHARED mappings */
341 	struct prio_tree_root	i_mmap;		/* tree of private and shared mappings */
342 	struct list_head	i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
343 	spinlock_t		i_mmap_lock;	/* protect tree, count, list */
344 	unsigned int		truncate_count;	/* Cover race condition with truncate */
345 	unsigned long		nrpages;	/* number of total pages */
346 	pgoff_t			writeback_index;/* writeback starts here */
347 	struct address_space_operations *a_ops;	/* methods */
348 	unsigned long		flags;		/* error bits/gfp mask */
349 	struct backing_dev_info *backing_dev_info; /* device readahead, etc */
350 	spinlock_t		private_lock;	/* for use by the address_space */
351 	struct list_head	private_list;	/* ditto */
352 	struct address_space	*assoc_mapping;	/* ditto */
353 } __attribute__((aligned(sizeof(long))));
354 	/*
355 	 * On most architectures that alignment is already the case; but
356 	 * must be enforced here for CRIS, to let the least signficant bit
357 	 * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
358 	 */
359 
360 struct block_device {
361 	dev_t			bd_dev;  /* not a kdev_t - it's a search key */
362 	struct inode *		bd_inode;	/* will die */
363 	int			bd_openers;
364 	struct semaphore	bd_sem;	/* open/close mutex */
365 	struct semaphore	bd_mount_sem;	/* mount mutex */
366 	struct list_head	bd_inodes;
367 	void *			bd_holder;
368 	int			bd_holders;
369 	struct block_device *	bd_contains;
370 	unsigned		bd_block_size;
371 	struct hd_struct *	bd_part;
372 	/* number of times partitions within this device have been opened. */
373 	unsigned		bd_part_count;
374 	int			bd_invalidated;
375 	struct gendisk *	bd_disk;
376 	struct list_head	bd_list;
377 	struct backing_dev_info *bd_inode_backing_dev_info;
378 	/*
379 	 * Private data.  You must have bd_claim'ed the block_device
380 	 * to use this.  NOTE:  bd_claim allows an owner to claim
381 	 * the same device multiple times, the owner must take special
382 	 * care to not mess up bd_private for that case.
383 	 */
384 	unsigned long		bd_private;
385 };
386 
387 /*
388  * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
389  * radix trees
390  */
391 #define PAGECACHE_TAG_DIRTY	0
392 #define PAGECACHE_TAG_WRITEBACK	1
393 
394 int mapping_tagged(struct address_space *mapping, int tag);
395 
396 /*
397  * Might pages of this file be mapped into userspace?
398  */
399 static inline int mapping_mapped(struct address_space *mapping)
400 {
401 	return	!prio_tree_empty(&mapping->i_mmap) ||
402 		!list_empty(&mapping->i_mmap_nonlinear);
403 }
404 
405 /*
406  * Might pages of this file have been modified in userspace?
407  * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
408  * marks vma as VM_SHARED if it is shared, and the file was opened for
409  * writing i.e. vma may be mprotected writable even if now readonly.
410  */
411 static inline int mapping_writably_mapped(struct address_space *mapping)
412 {
413 	return mapping->i_mmap_writable != 0;
414 }
415 
416 /*
417  * Use sequence counter to get consistent i_size on 32-bit processors.
418  */
419 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
420 #include <linux/seqlock.h>
421 #define __NEED_I_SIZE_ORDERED
422 #define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
423 #else
424 #define i_size_ordered_init(inode) do { } while (0)
425 #endif
426 
427 struct inode {
428 	struct hlist_node	i_hash;
429 	struct list_head	i_list;
430 	struct list_head	i_sb_list;
431 	struct list_head	i_dentry;
432 	unsigned long		i_ino;
433 	atomic_t		i_count;
434 	umode_t			i_mode;
435 	unsigned int		i_nlink;
436 	uid_t			i_uid;
437 	gid_t			i_gid;
438 	dev_t			i_rdev;
439 	loff_t			i_size;
440 	struct timespec		i_atime;
441 	struct timespec		i_mtime;
442 	struct timespec		i_ctime;
443 	unsigned int		i_blkbits;
444 	unsigned long		i_blksize;
445 	unsigned long		i_version;
446 	unsigned long		i_blocks;
447 	unsigned short          i_bytes;
448 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
449 	struct semaphore	i_sem;
450 	struct rw_semaphore	i_alloc_sem;
451 	struct inode_operations	*i_op;
452 	struct file_operations	*i_fop;	/* former ->i_op->default_file_ops */
453 	struct super_block	*i_sb;
454 	struct file_lock	*i_flock;
455 	struct address_space	*i_mapping;
456 	struct address_space	i_data;
457 #ifdef CONFIG_QUOTA
458 	struct dquot		*i_dquot[MAXQUOTAS];
459 #endif
460 	/* These three should probably be a union */
461 	struct list_head	i_devices;
462 	struct pipe_inode_info	*i_pipe;
463 	struct block_device	*i_bdev;
464 	struct cdev		*i_cdev;
465 	int			i_cindex;
466 
467 	__u32			i_generation;
468 
469 #ifdef CONFIG_DNOTIFY
470 	unsigned long		i_dnotify_mask; /* Directory notify events */
471 	struct dnotify_struct	*i_dnotify; /* for directory notifications */
472 #endif
473 
474 	unsigned long		i_state;
475 	unsigned long		dirtied_when;	/* jiffies of first dirtying */
476 
477 	unsigned int		i_flags;
478 
479 	atomic_t		i_writecount;
480 	void			*i_security;
481 	union {
482 		void		*generic_ip;
483 	} u;
484 #ifdef __NEED_I_SIZE_ORDERED
485 	seqcount_t		i_size_seqcount;
486 #endif
487 };
488 
489 /*
490  * NOTE: in a 32bit arch with a preemptable kernel and
491  * an UP compile the i_size_read/write must be atomic
492  * with respect to the local cpu (unlike with preempt disabled),
493  * but they don't need to be atomic with respect to other cpus like in
494  * true SMP (so they need either to either locally disable irq around
495  * the read or for example on x86 they can be still implemented as a
496  * cmpxchg8b without the need of the lock prefix). For SMP compiles
497  * and 64bit archs it makes no difference if preempt is enabled or not.
498  */
499 static inline loff_t i_size_read(struct inode *inode)
500 {
501 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
502 	loff_t i_size;
503 	unsigned int seq;
504 
505 	do {
506 		seq = read_seqcount_begin(&inode->i_size_seqcount);
507 		i_size = inode->i_size;
508 	} while (read_seqcount_retry(&inode->i_size_seqcount, seq));
509 	return i_size;
510 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
511 	loff_t i_size;
512 
513 	preempt_disable();
514 	i_size = inode->i_size;
515 	preempt_enable();
516 	return i_size;
517 #else
518 	return inode->i_size;
519 #endif
520 }
521 
522 
523 static inline void i_size_write(struct inode *inode, loff_t i_size)
524 {
525 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
526 	write_seqcount_begin(&inode->i_size_seqcount);
527 	inode->i_size = i_size;
528 	write_seqcount_end(&inode->i_size_seqcount);
529 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
530 	preempt_disable();
531 	inode->i_size = i_size;
532 	preempt_enable();
533 #else
534 	inode->i_size = i_size;
535 #endif
536 }
537 
538 static inline unsigned iminor(struct inode *inode)
539 {
540 	return MINOR(inode->i_rdev);
541 }
542 
543 static inline unsigned imajor(struct inode *inode)
544 {
545 	return MAJOR(inode->i_rdev);
546 }
547 
548 extern struct block_device *I_BDEV(struct inode *inode);
549 
550 struct fown_struct {
551 	rwlock_t lock;          /* protects pid, uid, euid fields */
552 	int pid;		/* pid or -pgrp where SIGIO should be sent */
553 	uid_t uid, euid;	/* uid/euid of process setting the owner */
554 	void *security;
555 	int signum;		/* posix.1b rt signal to be delivered on IO */
556 };
557 
558 /*
559  * Track a single file's readahead state
560  */
561 struct file_ra_state {
562 	unsigned long start;		/* Current window */
563 	unsigned long size;
564 	unsigned long flags;		/* ra flags RA_FLAG_xxx*/
565 	unsigned long cache_hit;	/* cache hit count*/
566 	unsigned long prev_page;	/* Cache last read() position */
567 	unsigned long ahead_start;	/* Ahead window */
568 	unsigned long ahead_size;
569 	unsigned long ra_pages;		/* Maximum readahead window */
570 	unsigned long mmap_hit;		/* Cache hit stat for mmap accesses */
571 	unsigned long mmap_miss;	/* Cache miss stat for mmap accesses */
572 };
573 #define RA_FLAG_MISS 0x01	/* a cache miss occured against this file */
574 #define RA_FLAG_INCACHE 0x02	/* file is already in cache */
575 
576 struct file {
577 	struct list_head	f_list;
578 	struct dentry		*f_dentry;
579 	struct vfsmount         *f_vfsmnt;
580 	struct file_operations	*f_op;
581 	atomic_t		f_count;
582 	unsigned int 		f_flags;
583 	mode_t			f_mode;
584 	int			f_error;
585 	loff_t			f_pos;
586 	struct fown_struct	f_owner;
587 	unsigned int		f_uid, f_gid;
588 	struct file_ra_state	f_ra;
589 
590 	size_t			f_maxcount;
591 	unsigned long		f_version;
592 	void			*f_security;
593 
594 	/* needed for tty driver, and maybe others */
595 	void			*private_data;
596 
597 #ifdef CONFIG_EPOLL
598 	/* Used by fs/eventpoll.c to link all the hooks to this file */
599 	struct list_head	f_ep_links;
600 	spinlock_t		f_ep_lock;
601 #endif /* #ifdef CONFIG_EPOLL */
602 	struct address_space	*f_mapping;
603 };
604 extern spinlock_t files_lock;
605 #define file_list_lock() spin_lock(&files_lock);
606 #define file_list_unlock() spin_unlock(&files_lock);
607 
608 #define get_file(x)	atomic_inc(&(x)->f_count)
609 #define file_count(x)	atomic_read(&(x)->f_count)
610 
611 #define	MAX_NON_LFS	((1UL<<31) - 1)
612 
613 /* Page cache limit. The filesystems should put that into their s_maxbytes
614    limits, otherwise bad things can happen in VM. */
615 #if BITS_PER_LONG==32
616 #define MAX_LFS_FILESIZE	(((u64)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1)
617 #elif BITS_PER_LONG==64
618 #define MAX_LFS_FILESIZE 	0x7fffffffffffffffUL
619 #endif
620 
621 #define FL_POSIX	1
622 #define FL_FLOCK	2
623 #define FL_ACCESS	8	/* not trying to lock, just looking */
624 #define FL_LOCKD	16	/* lock held by rpc.lockd */
625 #define FL_LEASE	32	/* lease held on this file */
626 #define FL_SLEEP	128	/* A blocking lock */
627 
628 /*
629  * The POSIX file lock owner is determined by
630  * the "struct files_struct" in the thread group
631  * (or NULL for no owner - BSD locks).
632  *
633  * Lockd stuffs a "host" pointer into this.
634  */
635 typedef struct files_struct *fl_owner_t;
636 
637 struct file_lock_operations {
638 	void (*fl_insert)(struct file_lock *);	/* lock insertion callback */
639 	void (*fl_remove)(struct file_lock *);	/* lock removal callback */
640 	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
641 	void (*fl_release_private)(struct file_lock *);
642 };
643 
644 struct lock_manager_operations {
645 	int (*fl_compare_owner)(struct file_lock *, struct file_lock *);
646 	void (*fl_notify)(struct file_lock *);	/* unblock callback */
647 	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
648 	void (*fl_release_private)(struct file_lock *);
649 	void (*fl_break)(struct file_lock *);
650 	int (*fl_mylease)(struct file_lock *, struct file_lock *);
651 	int (*fl_change)(struct file_lock **, int);
652 };
653 
654 /* that will die - we need it for nfs_lock_info */
655 #include <linux/nfs_fs_i.h>
656 
657 struct file_lock {
658 	struct file_lock *fl_next;	/* singly linked list for this inode  */
659 	struct list_head fl_link;	/* doubly linked list of all locks */
660 	struct list_head fl_block;	/* circular list of blocked processes */
661 	fl_owner_t fl_owner;
662 	unsigned int fl_pid;
663 	wait_queue_head_t fl_wait;
664 	struct file *fl_file;
665 	unsigned char fl_flags;
666 	unsigned char fl_type;
667 	loff_t fl_start;
668 	loff_t fl_end;
669 
670 	struct fasync_struct *	fl_fasync; /* for lease break notifications */
671 	unsigned long fl_break_time;	/* for nonblocking lease breaks */
672 
673 	struct file_lock_operations *fl_ops;	/* Callbacks for filesystems */
674 	struct lock_manager_operations *fl_lmops;	/* Callbacks for lockmanagers */
675 	union {
676 		struct nfs_lock_info	nfs_fl;
677 	} fl_u;
678 };
679 
680 /* The following constant reflects the upper bound of the file/locking space */
681 #ifndef OFFSET_MAX
682 #define INT_LIMIT(x)	(~((x)1 << (sizeof(x)*8 - 1)))
683 #define OFFSET_MAX	INT_LIMIT(loff_t)
684 #define OFFT_OFFSET_MAX	INT_LIMIT(off_t)
685 #endif
686 
687 extern struct list_head file_lock_list;
688 
689 #include <linux/fcntl.h>
690 
691 extern int fcntl_getlk(struct file *, struct flock __user *);
692 extern int fcntl_setlk(struct file *, unsigned int, struct flock __user *);
693 
694 #if BITS_PER_LONG == 32
695 extern int fcntl_getlk64(struct file *, struct flock64 __user *);
696 extern int fcntl_setlk64(struct file *, unsigned int, struct flock64 __user *);
697 #endif
698 
699 extern void send_sigio(struct fown_struct *fown, int fd, int band);
700 extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
701 extern int fcntl_getlease(struct file *filp);
702 
703 /* fs/locks.c */
704 extern void locks_init_lock(struct file_lock *);
705 extern void locks_copy_lock(struct file_lock *, struct file_lock *);
706 extern void locks_remove_posix(struct file *, fl_owner_t);
707 extern void locks_remove_flock(struct file *);
708 extern struct file_lock *posix_test_lock(struct file *, struct file_lock *);
709 extern int posix_lock_file(struct file *, struct file_lock *);
710 extern int posix_lock_file_wait(struct file *, struct file_lock *);
711 extern void posix_block_lock(struct file_lock *, struct file_lock *);
712 extern void posix_unblock_lock(struct file *, struct file_lock *);
713 extern int posix_locks_deadlock(struct file_lock *, struct file_lock *);
714 extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
715 extern int __break_lease(struct inode *inode, unsigned int flags);
716 extern void lease_get_mtime(struct inode *, struct timespec *time);
717 extern int setlease(struct file *, long, struct file_lock **);
718 extern int lease_modify(struct file_lock **, int);
719 extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
720 extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
721 extern void steal_locks(fl_owner_t from);
722 
723 struct fasync_struct {
724 	int	magic;
725 	int	fa_fd;
726 	struct	fasync_struct	*fa_next; /* singly linked list */
727 	struct	file 		*fa_file;
728 };
729 
730 #define FASYNC_MAGIC 0x4601
731 
732 /* SMP safe fasync helpers: */
733 extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
734 /* can be called from interrupts */
735 extern void kill_fasync(struct fasync_struct **, int, int);
736 /* only for net: no internal synchronization */
737 extern void __kill_fasync(struct fasync_struct *, int, int);
738 
739 extern int f_setown(struct file *filp, unsigned long arg, int force);
740 extern void f_delown(struct file *filp);
741 extern int send_sigurg(struct fown_struct *fown);
742 
743 /*
744  *	Umount options
745  */
746 
747 #define MNT_FORCE	0x00000001	/* Attempt to forcibily umount */
748 #define MNT_DETACH	0x00000002	/* Just detach from the tree */
749 #define MNT_EXPIRE	0x00000004	/* Mark for expiry */
750 
751 extern struct list_head super_blocks;
752 extern spinlock_t sb_lock;
753 
754 #define sb_entry(list)	list_entry((list), struct super_block, s_list)
755 #define S_BIAS (1<<30)
756 struct super_block {
757 	struct list_head	s_list;		/* Keep this first */
758 	dev_t			s_dev;		/* search index; _not_ kdev_t */
759 	unsigned long		s_blocksize;
760 	unsigned long		s_old_blocksize;
761 	unsigned char		s_blocksize_bits;
762 	unsigned char		s_dirt;
763 	unsigned long long	s_maxbytes;	/* Max file size */
764 	struct file_system_type	*s_type;
765 	struct super_operations	*s_op;
766 	struct dquot_operations	*dq_op;
767  	struct quotactl_ops	*s_qcop;
768 	struct export_operations *s_export_op;
769 	unsigned long		s_flags;
770 	unsigned long		s_magic;
771 	struct dentry		*s_root;
772 	struct rw_semaphore	s_umount;
773 	struct semaphore	s_lock;
774 	int			s_count;
775 	int			s_syncing;
776 	int			s_need_sync_fs;
777 	atomic_t		s_active;
778 	void                    *s_security;
779 	struct xattr_handler	**s_xattr;
780 
781 	struct list_head	s_inodes;	/* all inodes */
782 	struct list_head	s_dirty;	/* dirty inodes */
783 	struct list_head	s_io;		/* parked for writeback */
784 	struct hlist_head	s_anon;		/* anonymous dentries for (nfs) exporting */
785 	struct list_head	s_files;
786 
787 	struct block_device	*s_bdev;
788 	struct list_head	s_instances;
789 	struct quota_info	s_dquot;	/* Diskquota specific options */
790 
791 	int			s_frozen;
792 	wait_queue_head_t	s_wait_unfrozen;
793 
794 	char s_id[32];				/* Informational name */
795 
796 	void 			*s_fs_info;	/* Filesystem private info */
797 
798 	/*
799 	 * The next field is for VFS *only*. No filesystems have any business
800 	 * even looking at it. You had been warned.
801 	 */
802 	struct semaphore s_vfs_rename_sem;	/* Kludge */
803 
804 	/* Granuality of c/m/atime in ns.
805 	   Cannot be worse than a second */
806 	u32		   s_time_gran;
807 };
808 
809 extern struct timespec current_fs_time(struct super_block *sb);
810 
811 /*
812  * Snapshotting support.
813  */
814 enum {
815 	SB_UNFROZEN = 0,
816 	SB_FREEZE_WRITE	= 1,
817 	SB_FREEZE_TRANS = 2,
818 };
819 
820 #define vfs_check_frozen(sb, level) \
821 	wait_event((sb)->s_wait_unfrozen, ((sb)->s_frozen < (level)))
822 
823 /*
824  * Superblock locking.
825  */
826 static inline void lock_super(struct super_block * sb)
827 {
828 	down(&sb->s_lock);
829 }
830 
831 static inline void unlock_super(struct super_block * sb)
832 {
833 	up(&sb->s_lock);
834 }
835 
836 /*
837  * VFS helper functions..
838  */
839 extern int vfs_create(struct inode *, struct dentry *, int, struct nameidata *);
840 extern int vfs_mkdir(struct inode *, struct dentry *, int);
841 extern int vfs_mknod(struct inode *, struct dentry *, int, dev_t);
842 extern int vfs_symlink(struct inode *, struct dentry *, const char *, int);
843 extern int vfs_link(struct dentry *, struct inode *, struct dentry *);
844 extern int vfs_rmdir(struct inode *, struct dentry *);
845 extern int vfs_unlink(struct inode *, struct dentry *);
846 extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
847 
848 /*
849  * VFS dentry helper functions.
850  */
851 extern void dentry_unhash(struct dentry *dentry);
852 
853 /*
854  * File types
855  *
856  * NOTE! These match bits 12..15 of stat.st_mode
857  * (ie "(i_mode >> 12) & 15").
858  */
859 #define DT_UNKNOWN	0
860 #define DT_FIFO		1
861 #define DT_CHR		2
862 #define DT_DIR		4
863 #define DT_BLK		6
864 #define DT_REG		8
865 #define DT_LNK		10
866 #define DT_SOCK		12
867 #define DT_WHT		14
868 
869 #define OSYNC_METADATA	(1<<0)
870 #define OSYNC_DATA	(1<<1)
871 #define OSYNC_INODE	(1<<2)
872 int generic_osync_inode(struct inode *, struct address_space *, int);
873 
874 /*
875  * This is the "filldir" function type, used by readdir() to let
876  * the kernel specify what kind of dirent layout it wants to have.
877  * This allows the kernel to read directories into kernel space or
878  * to have different dirent layouts depending on the binary type.
879  */
880 typedef int (*filldir_t)(void *, const char *, int, loff_t, ino_t, unsigned);
881 
882 struct block_device_operations {
883 	int (*open) (struct inode *, struct file *);
884 	int (*release) (struct inode *, struct file *);
885 	int (*ioctl) (struct inode *, struct file *, unsigned, unsigned long);
886 	long (*compat_ioctl) (struct file *, unsigned, unsigned long);
887 	int (*media_changed) (struct gendisk *);
888 	int (*revalidate_disk) (struct gendisk *);
889 	struct module *owner;
890 };
891 
892 /*
893  * "descriptor" for what we're up to with a read for sendfile().
894  * This allows us to use the same read code yet
895  * have multiple different users of the data that
896  * we read from a file.
897  *
898  * The simplest case just copies the data to user
899  * mode.
900  */
901 typedef struct {
902 	size_t written;
903 	size_t count;
904 	union {
905 		char __user * buf;
906 		void *data;
907 	} arg;
908 	int error;
909 } read_descriptor_t;
910 
911 typedef int (*read_actor_t)(read_descriptor_t *, struct page *, unsigned long, unsigned long);
912 
913 /* These macros are for out of kernel modules to test that
914  * the kernel supports the unlocked_ioctl and compat_ioctl
915  * fields in struct file_operations. */
916 #define HAVE_COMPAT_IOCTL 1
917 #define HAVE_UNLOCKED_IOCTL 1
918 
919 /*
920  * NOTE:
921  * read, write, poll, fsync, readv, writev, unlocked_ioctl and compat_ioctl
922  * can be called without the big kernel lock held in all filesystems.
923  */
924 struct file_operations {
925 	struct module *owner;
926 	loff_t (*llseek) (struct file *, loff_t, int);
927 	ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
928 	ssize_t (*aio_read) (struct kiocb *, char __user *, size_t, loff_t);
929 	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
930 	ssize_t (*aio_write) (struct kiocb *, const char __user *, size_t, loff_t);
931 	int (*readdir) (struct file *, void *, filldir_t);
932 	unsigned int (*poll) (struct file *, struct poll_table_struct *);
933 	int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
934 	long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
935 	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
936 	int (*mmap) (struct file *, struct vm_area_struct *);
937 	int (*open) (struct inode *, struct file *);
938 	int (*flush) (struct file *);
939 	int (*release) (struct inode *, struct file *);
940 	int (*fsync) (struct file *, struct dentry *, int datasync);
941 	int (*aio_fsync) (struct kiocb *, int datasync);
942 	int (*fasync) (int, struct file *, int);
943 	int (*lock) (struct file *, int, struct file_lock *);
944 	ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
945 	ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
946 	ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *);
947 	ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
948 	unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
949 	int (*check_flags)(int);
950 	int (*dir_notify)(struct file *filp, unsigned long arg);
951 	int (*flock) (struct file *, int, struct file_lock *);
952 };
953 
954 struct inode_operations {
955 	int (*create) (struct inode *,struct dentry *,int, struct nameidata *);
956 	struct dentry * (*lookup) (struct inode *,struct dentry *, struct nameidata *);
957 	int (*link) (struct dentry *,struct inode *,struct dentry *);
958 	int (*unlink) (struct inode *,struct dentry *);
959 	int (*symlink) (struct inode *,struct dentry *,const char *);
960 	int (*mkdir) (struct inode *,struct dentry *,int);
961 	int (*rmdir) (struct inode *,struct dentry *);
962 	int (*mknod) (struct inode *,struct dentry *,int,dev_t);
963 	int (*rename) (struct inode *, struct dentry *,
964 			struct inode *, struct dentry *);
965 	int (*readlink) (struct dentry *, char __user *,int);
966 	int (*follow_link) (struct dentry *, struct nameidata *);
967 	void (*put_link) (struct dentry *, struct nameidata *);
968 	void (*truncate) (struct inode *);
969 	int (*permission) (struct inode *, int, struct nameidata *);
970 	int (*setattr) (struct dentry *, struct iattr *);
971 	int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
972 	int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
973 	ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
974 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
975 	int (*removexattr) (struct dentry *, const char *);
976 };
977 
978 struct seq_file;
979 
980 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
981 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
982 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
983 		unsigned long, loff_t *);
984 extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
985 		unsigned long, loff_t *);
986 
987 /*
988  * NOTE: write_inode, delete_inode, clear_inode, put_inode can be called
989  * without the big kernel lock held in all filesystems.
990  */
991 struct super_operations {
992    	struct inode *(*alloc_inode)(struct super_block *sb);
993 	void (*destroy_inode)(struct inode *);
994 
995 	void (*read_inode) (struct inode *);
996 
997    	void (*dirty_inode) (struct inode *);
998 	int (*write_inode) (struct inode *, int);
999 	void (*put_inode) (struct inode *);
1000 	void (*drop_inode) (struct inode *);
1001 	void (*delete_inode) (struct inode *);
1002 	void (*put_super) (struct super_block *);
1003 	void (*write_super) (struct super_block *);
1004 	int (*sync_fs)(struct super_block *sb, int wait);
1005 	void (*write_super_lockfs) (struct super_block *);
1006 	void (*unlockfs) (struct super_block *);
1007 	int (*statfs) (struct super_block *, struct kstatfs *);
1008 	int (*remount_fs) (struct super_block *, int *, char *);
1009 	void (*clear_inode) (struct inode *);
1010 	void (*umount_begin) (struct super_block *);
1011 
1012 	int (*show_options)(struct seq_file *, struct vfsmount *);
1013 
1014 	ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
1015 	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
1016 };
1017 
1018 /* Inode state bits.  Protected by inode_lock. */
1019 #define I_DIRTY_SYNC		1 /* Not dirty enough for O_DATASYNC */
1020 #define I_DIRTY_DATASYNC	2 /* Data-related inode changes pending */
1021 #define I_DIRTY_PAGES		4 /* Data-related inode changes pending */
1022 #define __I_LOCK		3
1023 #define I_LOCK			(1 << __I_LOCK)
1024 #define I_FREEING		16
1025 #define I_CLEAR			32
1026 #define I_NEW			64
1027 
1028 #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)
1029 
1030 extern void __mark_inode_dirty(struct inode *, int);
1031 static inline void mark_inode_dirty(struct inode *inode)
1032 {
1033 	__mark_inode_dirty(inode, I_DIRTY);
1034 }
1035 
1036 static inline void mark_inode_dirty_sync(struct inode *inode)
1037 {
1038 	__mark_inode_dirty(inode, I_DIRTY_SYNC);
1039 }
1040 
1041 static inline void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
1042 {
1043 	/* per-mountpoint checks will go here */
1044 	update_atime(dentry->d_inode);
1045 }
1046 
1047 static inline void file_accessed(struct file *file)
1048 {
1049 	if (!(file->f_flags & O_NOATIME))
1050 		touch_atime(file->f_vfsmnt, file->f_dentry);
1051 }
1052 
1053 int sync_inode(struct inode *inode, struct writeback_control *wbc);
1054 
1055 /**
1056  * struct export_operations - for nfsd to communicate with file systems
1057  * @decode_fh:      decode a file handle fragment and return a &struct dentry
1058  * @encode_fh:      encode a file handle fragment from a dentry
1059  * @get_name:       find the name for a given inode in a given directory
1060  * @get_parent:     find the parent of a given directory
1061  * @get_dentry:     find a dentry for the inode given a file handle sub-fragment
1062  *
1063  * Description:
1064  *    The export_operations structure provides a means for nfsd to communicate
1065  *    with a particular exported file system  - particularly enabling nfsd and
1066  *    the filesystem to co-operate when dealing with file handles.
1067  *
1068  *    export_operations contains two basic operation for dealing with file
1069  *    handles, decode_fh() and encode_fh(), and allows for some other
1070  *    operations to be defined which standard helper routines use to get
1071  *    specific information from the filesystem.
1072  *
1073  *    nfsd encodes information use to determine which filesystem a filehandle
1074  *    applies to in the initial part of the file handle.  The remainder, termed
1075  *    a file handle fragment, is controlled completely by the filesystem.  The
1076  *    standard helper routines assume that this fragment will contain one or
1077  *    two sub-fragments, one which identifies the file, and one which may be
1078  *    used to identify the (a) directory containing the file.
1079  *
1080  *    In some situations, nfsd needs to get a dentry which is connected into a
1081  *    specific part of the file tree.  To allow for this, it passes the
1082  *    function acceptable() together with a @context which can be used to see
1083  *    if the dentry is acceptable.  As there can be multiple dentrys for a
1084  *    given file, the filesystem should check each one for acceptability before
1085  *    looking for the next.  As soon as an acceptable one is found, it should
1086  *    be returned.
1087  *
1088  * decode_fh:
1089  *    @decode_fh is given a &struct super_block (@sb), a file handle fragment
1090  *    (@fh, @fh_len) and an acceptability testing function (@acceptable,
1091  *    @context).  It should return a &struct dentry which refers to the same
1092  *    file that the file handle fragment refers to,  and which passes the
1093  *    acceptability test.  If it cannot, it should return a %NULL pointer if
1094  *    the file was found but no acceptable &dentries were available, or a
1095  *    %ERR_PTR error code indicating why it couldn't be found (e.g. %ENOENT or
1096  *    %ENOMEM).
1097  *
1098  * encode_fh:
1099  *    @encode_fh should store in the file handle fragment @fh (using at most
1100  *    @max_len bytes) information that can be used by @decode_fh to recover the
1101  *    file refered to by the &struct dentry @de.  If the @connectable flag is
1102  *    set, the encode_fh() should store sufficient information so that a good
1103  *    attempt can be made to find not only the file but also it's place in the
1104  *    filesystem.   This typically means storing a reference to de->d_parent in
1105  *    the filehandle fragment.  encode_fh() should return the number of bytes
1106  *    stored or a negative error code such as %-ENOSPC
1107  *
1108  * get_name:
1109  *    @get_name should find a name for the given @child in the given @parent
1110  *    directory.  The name should be stored in the @name (with the
1111  *    understanding that it is already pointing to a a %NAME_MAX+1 sized
1112  *    buffer.   get_name() should return %0 on success, a negative error code
1113  *    or error.  @get_name will be called without @parent->i_sem held.
1114  *
1115  * get_parent:
1116  *    @get_parent should find the parent directory for the given @child which
1117  *    is also a directory.  In the event that it cannot be found, or storage
1118  *    space cannot be allocated, a %ERR_PTR should be returned.
1119  *
1120  * get_dentry:
1121  *    Given a &super_block (@sb) and a pointer to a file-system specific inode
1122  *    identifier, possibly an inode number, (@inump) get_dentry() should find
1123  *    the identified inode and return a dentry for that inode.  Any suitable
1124  *    dentry can be returned including, if necessary, a new dentry created with
1125  *    d_alloc_root.  The caller can then find any other extant dentrys by
1126  *    following the d_alias links.  If a new dentry was created using
1127  *    d_alloc_root, DCACHE_NFSD_DISCONNECTED should be set, and the dentry
1128  *    should be d_rehash()ed.
1129  *
1130  *    If the inode cannot be found, either a %NULL pointer or an %ERR_PTR code
1131  *    can be returned.  The @inump will be whatever was passed to
1132  *    nfsd_find_fh_dentry() in either the @obj or @parent parameters.
1133  *
1134  * Locking rules:
1135  *    get_parent is called with child->d_inode->i_sem down
1136  *    get_name is not (which is possibly inconsistent)
1137  */
1138 
1139 struct export_operations {
1140 	struct dentry *(*decode_fh)(struct super_block *sb, __u32 *fh, int fh_len, int fh_type,
1141 			 int (*acceptable)(void *context, struct dentry *de),
1142 			 void *context);
1143 	int (*encode_fh)(struct dentry *de, __u32 *fh, int *max_len,
1144 			 int connectable);
1145 
1146 	/* the following are only called from the filesystem itself */
1147 	int (*get_name)(struct dentry *parent, char *name,
1148 			struct dentry *child);
1149 	struct dentry * (*get_parent)(struct dentry *child);
1150 	struct dentry * (*get_dentry)(struct super_block *sb, void *inump);
1151 
1152 	/* This is set by the exporting module to a standard helper */
1153 	struct dentry * (*find_exported_dentry)(
1154 		struct super_block *sb, void *obj, void *parent,
1155 		int (*acceptable)(void *context, struct dentry *de),
1156 		void *context);
1157 
1158 
1159 };
1160 
1161 extern struct dentry *
1162 find_exported_dentry(struct super_block *sb, void *obj, void *parent,
1163 		     int (*acceptable)(void *context, struct dentry *de),
1164 		     void *context);
1165 
1166 struct file_system_type {
1167 	const char *name;
1168 	int fs_flags;
1169 	struct super_block *(*get_sb) (struct file_system_type *, int,
1170 				       const char *, void *);
1171 	void (*kill_sb) (struct super_block *);
1172 	struct module *owner;
1173 	struct file_system_type * next;
1174 	struct list_head fs_supers;
1175 };
1176 
1177 struct super_block *get_sb_bdev(struct file_system_type *fs_type,
1178 	int flags, const char *dev_name, void *data,
1179 	int (*fill_super)(struct super_block *, void *, int));
1180 struct super_block *get_sb_single(struct file_system_type *fs_type,
1181 	int flags, void *data,
1182 	int (*fill_super)(struct super_block *, void *, int));
1183 struct super_block *get_sb_nodev(struct file_system_type *fs_type,
1184 	int flags, void *data,
1185 	int (*fill_super)(struct super_block *, void *, int));
1186 void generic_shutdown_super(struct super_block *sb);
1187 void kill_block_super(struct super_block *sb);
1188 void kill_anon_super(struct super_block *sb);
1189 void kill_litter_super(struct super_block *sb);
1190 void deactivate_super(struct super_block *sb);
1191 int set_anon_super(struct super_block *s, void *data);
1192 struct super_block *sget(struct file_system_type *type,
1193 			int (*test)(struct super_block *,void *),
1194 			int (*set)(struct super_block *,void *),
1195 			void *data);
1196 struct super_block *get_sb_pseudo(struct file_system_type *, char *,
1197 			struct super_operations *ops, unsigned long);
1198 int __put_super(struct super_block *sb);
1199 int __put_super_and_need_restart(struct super_block *sb);
1200 void unnamed_dev_init(void);
1201 
1202 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
1203 #define fops_get(fops) \
1204 	(((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
1205 #define fops_put(fops) \
1206 	do { if (fops) module_put((fops)->owner); } while(0)
1207 
1208 extern int register_filesystem(struct file_system_type *);
1209 extern int unregister_filesystem(struct file_system_type *);
1210 extern struct vfsmount *kern_mount(struct file_system_type *);
1211 extern int may_umount_tree(struct vfsmount *);
1212 extern int may_umount(struct vfsmount *);
1213 extern long do_mount(char *, char *, char *, unsigned long, void *);
1214 
1215 extern int vfs_statfs(struct super_block *, struct kstatfs *);
1216 
1217 #define FLOCK_VERIFY_READ  1
1218 #define FLOCK_VERIFY_WRITE 2
1219 
1220 extern int locks_mandatory_locked(struct inode *);
1221 extern int locks_mandatory_area(int, struct inode *, struct file *, loff_t, size_t);
1222 
1223 /*
1224  * Candidates for mandatory locking have the setgid bit set
1225  * but no group execute bit -  an otherwise meaningless combination.
1226  */
1227 #define MANDATORY_LOCK(inode) \
1228 	(IS_MANDLOCK(inode) && ((inode)->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
1229 
1230 static inline int locks_verify_locked(struct inode *inode)
1231 {
1232 	if (MANDATORY_LOCK(inode))
1233 		return locks_mandatory_locked(inode);
1234 	return 0;
1235 }
1236 
1237 extern int rw_verify_area(int, struct file *, loff_t *, size_t);
1238 
1239 static inline int locks_verify_truncate(struct inode *inode,
1240 				    struct file *filp,
1241 				    loff_t size)
1242 {
1243 	if (inode->i_flock && MANDATORY_LOCK(inode))
1244 		return locks_mandatory_area(
1245 			FLOCK_VERIFY_WRITE, inode, filp,
1246 			size < inode->i_size ? size : inode->i_size,
1247 			(size < inode->i_size ? inode->i_size - size
1248 			 : size - inode->i_size)
1249 		);
1250 	return 0;
1251 }
1252 
1253 static inline int break_lease(struct inode *inode, unsigned int mode)
1254 {
1255 	if (inode->i_flock)
1256 		return __break_lease(inode, mode);
1257 	return 0;
1258 }
1259 
1260 /* fs/open.c */
1261 
1262 extern int do_truncate(struct dentry *, loff_t start);
1263 extern struct file *filp_open(const char *, int, int);
1264 extern struct file * dentry_open(struct dentry *, struct vfsmount *, int);
1265 extern int filp_close(struct file *, fl_owner_t id);
1266 extern char * getname(const char __user *);
1267 
1268 /* fs/dcache.c */
1269 extern void __init vfs_caches_init_early(void);
1270 extern void __init vfs_caches_init(unsigned long);
1271 
1272 #define __getname()	kmem_cache_alloc(names_cachep, SLAB_KERNEL)
1273 #define __putname(name) kmem_cache_free(names_cachep, (void *)(name))
1274 #ifndef CONFIG_AUDITSYSCALL
1275 #define putname(name)   __putname(name)
1276 #else
1277 extern void putname(const char *name);
1278 #endif
1279 
1280 extern int register_blkdev(unsigned int, const char *);
1281 extern int unregister_blkdev(unsigned int, const char *);
1282 extern struct block_device *bdget(dev_t);
1283 extern void bd_set_size(struct block_device *, loff_t size);
1284 extern void bd_forget(struct inode *inode);
1285 extern void bdput(struct block_device *);
1286 extern struct block_device *open_by_devnum(dev_t, unsigned);
1287 extern struct file_operations def_blk_fops;
1288 extern struct address_space_operations def_blk_aops;
1289 extern struct file_operations def_chr_fops;
1290 extern struct file_operations bad_sock_fops;
1291 extern struct file_operations def_fifo_fops;
1292 extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
1293 extern int blkdev_ioctl(struct inode *, struct file *, unsigned, unsigned long);
1294 extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
1295 extern int blkdev_get(struct block_device *, mode_t, unsigned);
1296 extern int blkdev_put(struct block_device *);
1297 extern int bd_claim(struct block_device *, void *);
1298 extern void bd_release(struct block_device *);
1299 
1300 /* fs/char_dev.c */
1301 extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
1302 extern int register_chrdev_region(dev_t, unsigned, const char *);
1303 extern int register_chrdev(unsigned int, const char *,
1304 			   struct file_operations *);
1305 extern int unregister_chrdev(unsigned int, const char *);
1306 extern void unregister_chrdev_region(dev_t, unsigned);
1307 extern int chrdev_open(struct inode *, struct file *);
1308 
1309 /* fs/block_dev.c */
1310 #define BDEVNAME_SIZE	32	/* Largest string for a blockdev identifier */
1311 extern const char *__bdevname(dev_t, char *buffer);
1312 extern const char *bdevname(struct block_device *bdev, char *buffer);
1313 extern struct block_device *lookup_bdev(const char *);
1314 extern struct block_device *open_bdev_excl(const char *, int, void *);
1315 extern void close_bdev_excl(struct block_device *);
1316 
1317 extern void init_special_inode(struct inode *, umode_t, dev_t);
1318 
1319 /* Invalid inode operations -- fs/bad_inode.c */
1320 extern void make_bad_inode(struct inode *);
1321 extern int is_bad_inode(struct inode *);
1322 
1323 extern struct file_operations read_fifo_fops;
1324 extern struct file_operations write_fifo_fops;
1325 extern struct file_operations rdwr_fifo_fops;
1326 extern struct file_operations read_pipe_fops;
1327 extern struct file_operations write_pipe_fops;
1328 extern struct file_operations rdwr_pipe_fops;
1329 
1330 extern int fs_may_remount_ro(struct super_block *);
1331 
1332 /*
1333  * return READ, READA, or WRITE
1334  */
1335 #define bio_rw(bio)		((bio)->bi_rw & (RW_MASK | RWA_MASK))
1336 
1337 /*
1338  * return data direction, READ or WRITE
1339  */
1340 #define bio_data_dir(bio)	((bio)->bi_rw & 1)
1341 
1342 extern int check_disk_change(struct block_device *);
1343 extern int invalidate_inodes(struct super_block *);
1344 extern int __invalidate_device(struct block_device *, int);
1345 extern int invalidate_partition(struct gendisk *, int);
1346 unsigned long invalidate_mapping_pages(struct address_space *mapping,
1347 					pgoff_t start, pgoff_t end);
1348 unsigned long invalidate_inode_pages(struct address_space *mapping);
1349 static inline void invalidate_remote_inode(struct inode *inode)
1350 {
1351 	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1352 	    S_ISLNK(inode->i_mode))
1353 		invalidate_inode_pages(inode->i_mapping);
1354 }
1355 extern int invalidate_inode_pages2(struct address_space *mapping);
1356 extern int invalidate_inode_pages2_range(struct address_space *mapping,
1357 					 pgoff_t start, pgoff_t end);
1358 extern int write_inode_now(struct inode *, int);
1359 extern int filemap_fdatawrite(struct address_space *);
1360 extern int filemap_flush(struct address_space *);
1361 extern int filemap_fdatawait(struct address_space *);
1362 extern int filemap_write_and_wait(struct address_space *mapping);
1363 extern int filemap_write_and_wait_range(struct address_space *mapping,
1364 				        loff_t lstart, loff_t lend);
1365 extern void sync_supers(void);
1366 extern void sync_filesystems(int wait);
1367 extern void emergency_sync(void);
1368 extern void emergency_remount(void);
1369 extern int do_remount_sb(struct super_block *sb, int flags,
1370 			 void *data, int force);
1371 extern sector_t bmap(struct inode *, sector_t);
1372 extern int setattr_mask(unsigned int);
1373 extern int notify_change(struct dentry *, struct iattr *);
1374 extern int permission(struct inode *, int, struct nameidata *);
1375 extern int generic_permission(struct inode *, int,
1376 		int (*check_acl)(struct inode *, int));
1377 
1378 extern int get_write_access(struct inode *);
1379 extern int deny_write_access(struct file *);
1380 static inline void put_write_access(struct inode * inode)
1381 {
1382 	atomic_dec(&inode->i_writecount);
1383 }
1384 static inline void allow_write_access(struct file *file)
1385 {
1386 	if (file)
1387 		atomic_inc(&file->f_dentry->d_inode->i_writecount);
1388 }
1389 extern int do_pipe(int *);
1390 
1391 extern int open_namei(const char *, int, int, struct nameidata *);
1392 extern int may_open(struct nameidata *, int, int);
1393 
1394 extern int kernel_read(struct file *, unsigned long, char *, unsigned long);
1395 extern struct file * open_exec(const char *);
1396 
1397 /* fs/dcache.c -- generic fs support functions */
1398 extern int is_subdir(struct dentry *, struct dentry *);
1399 extern ino_t find_inode_number(struct dentry *, struct qstr *);
1400 
1401 #include <linux/err.h>
1402 
1403 /* needed for stackable file system support */
1404 extern loff_t default_llseek(struct file *file, loff_t offset, int origin);
1405 
1406 extern loff_t vfs_llseek(struct file *file, loff_t offset, int origin);
1407 
1408 extern void inode_init_once(struct inode *);
1409 extern void iput(struct inode *);
1410 extern struct inode * igrab(struct inode *);
1411 extern ino_t iunique(struct super_block *, ino_t);
1412 extern int inode_needs_sync(struct inode *inode);
1413 extern void generic_delete_inode(struct inode *inode);
1414 
1415 extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
1416 		int (*test)(struct inode *, void *), void *data);
1417 extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
1418 
1419 extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
1420 extern struct inode * iget_locked(struct super_block *, unsigned long);
1421 extern void unlock_new_inode(struct inode *);
1422 
1423 static inline struct inode *iget(struct super_block *sb, unsigned long ino)
1424 {
1425 	struct inode *inode = iget_locked(sb, ino);
1426 
1427 	if (inode && (inode->i_state & I_NEW)) {
1428 		sb->s_op->read_inode(inode);
1429 		unlock_new_inode(inode);
1430 	}
1431 
1432 	return inode;
1433 }
1434 
1435 extern void __iget(struct inode * inode);
1436 extern void clear_inode(struct inode *);
1437 extern void destroy_inode(struct inode *);
1438 extern struct inode *new_inode(struct super_block *);
1439 extern int remove_suid(struct dentry *);
1440 extern void remove_dquot_ref(struct super_block *, int, struct list_head *);
1441 extern struct semaphore iprune_sem;
1442 
1443 extern void __insert_inode_hash(struct inode *, unsigned long hashval);
1444 extern void remove_inode_hash(struct inode *);
1445 static inline void insert_inode_hash(struct inode *inode) {
1446 	__insert_inode_hash(inode, inode->i_ino);
1447 }
1448 
1449 extern struct file * get_empty_filp(void);
1450 extern void file_move(struct file *f, struct list_head *list);
1451 extern void file_kill(struct file *f);
1452 struct bio;
1453 extern void submit_bio(int, struct bio *);
1454 extern int bdev_read_only(struct block_device *);
1455 extern int set_blocksize(struct block_device *, int);
1456 extern int sb_set_blocksize(struct super_block *, int);
1457 extern int sb_min_blocksize(struct super_block *, int);
1458 
1459 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
1460 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
1461 extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
1462 extern int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
1463 extern ssize_t generic_file_read(struct file *, char __user *, size_t, loff_t *);
1464 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
1465 extern ssize_t generic_file_write(struct file *, const char __user *, size_t, loff_t *);
1466 extern ssize_t generic_file_aio_read(struct kiocb *, char __user *, size_t, loff_t);
1467 extern ssize_t __generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t *);
1468 extern ssize_t generic_file_aio_write(struct kiocb *, const char __user *, size_t, loff_t);
1469 extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct iovec *,
1470 		unsigned long, loff_t *);
1471 extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
1472 		unsigned long *, loff_t, loff_t *, size_t, size_t);
1473 extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
1474 		unsigned long, loff_t, loff_t *, size_t, ssize_t);
1475 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
1476 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
1477 ssize_t generic_file_write_nolock(struct file *file, const struct iovec *iov,
1478 				unsigned long nr_segs, loff_t *ppos);
1479 extern ssize_t generic_file_sendfile(struct file *, loff_t *, size_t, read_actor_t, void *);
1480 extern void do_generic_mapping_read(struct address_space *mapping,
1481 				    struct file_ra_state *, struct file *,
1482 				    loff_t *, read_descriptor_t *, read_actor_t);
1483 extern void
1484 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
1485 extern ssize_t generic_file_direct_IO(int rw, struct kiocb *iocb,
1486 	const struct iovec *iov, loff_t offset, unsigned long nr_segs);
1487 extern ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
1488 	unsigned long nr_segs, loff_t *ppos);
1489 ssize_t generic_file_writev(struct file *filp, const struct iovec *iov,
1490 			unsigned long nr_segs, loff_t *ppos);
1491 extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
1492 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
1493 extern loff_t remote_llseek(struct file *file, loff_t offset, int origin);
1494 extern int generic_file_open(struct inode * inode, struct file * filp);
1495 extern int nonseekable_open(struct inode * inode, struct file * filp);
1496 
1497 static inline void do_generic_file_read(struct file * filp, loff_t *ppos,
1498 					read_descriptor_t * desc,
1499 					read_actor_t actor)
1500 {
1501 	do_generic_mapping_read(filp->f_mapping,
1502 				&filp->f_ra,
1503 				filp,
1504 				ppos,
1505 				desc,
1506 				actor);
1507 }
1508 
1509 ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
1510 	struct block_device *bdev, const struct iovec *iov, loff_t offset,
1511 	unsigned long nr_segs, get_blocks_t get_blocks, dio_iodone_t end_io,
1512 	int lock_type);
1513 
1514 enum {
1515 	DIO_LOCKING = 1, /* need locking between buffered and direct access */
1516 	DIO_NO_LOCKING,  /* bdev; no locking at all between buffered/direct */
1517 	DIO_OWN_LOCKING, /* filesystem locks buffered and direct internally */
1518 };
1519 
1520 static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
1521 	struct inode *inode, struct block_device *bdev, const struct iovec *iov,
1522 	loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
1523 	dio_iodone_t end_io)
1524 {
1525 	return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
1526 				nr_segs, get_blocks, end_io, DIO_LOCKING);
1527 }
1528 
1529 static inline ssize_t blockdev_direct_IO_no_locking(int rw, struct kiocb *iocb,
1530 	struct inode *inode, struct block_device *bdev, const struct iovec *iov,
1531 	loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
1532 	dio_iodone_t end_io)
1533 {
1534 	return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
1535 				nr_segs, get_blocks, end_io, DIO_NO_LOCKING);
1536 }
1537 
1538 static inline ssize_t blockdev_direct_IO_own_locking(int rw, struct kiocb *iocb,
1539 	struct inode *inode, struct block_device *bdev, const struct iovec *iov,
1540 	loff_t offset, unsigned long nr_segs, get_blocks_t get_blocks,
1541 	dio_iodone_t end_io)
1542 {
1543 	return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
1544 				nr_segs, get_blocks, end_io, DIO_OWN_LOCKING);
1545 }
1546 
1547 extern struct file_operations generic_ro_fops;
1548 
1549 #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
1550 
1551 extern int vfs_readlink(struct dentry *, char __user *, int, const char *);
1552 extern int vfs_follow_link(struct nameidata *, const char *);
1553 extern int page_readlink(struct dentry *, char __user *, int);
1554 extern int page_follow_link_light(struct dentry *, struct nameidata *);
1555 extern void page_put_link(struct dentry *, struct nameidata *);
1556 extern int page_symlink(struct inode *inode, const char *symname, int len);
1557 extern struct inode_operations page_symlink_inode_operations;
1558 extern int generic_readlink(struct dentry *, char __user *, int);
1559 extern void generic_fillattr(struct inode *, struct kstat *);
1560 extern int vfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
1561 void inode_add_bytes(struct inode *inode, loff_t bytes);
1562 void inode_sub_bytes(struct inode *inode, loff_t bytes);
1563 loff_t inode_get_bytes(struct inode *inode);
1564 void inode_set_bytes(struct inode *inode, loff_t bytes);
1565 
1566 extern int vfs_readdir(struct file *, filldir_t, void *);
1567 
1568 extern int vfs_stat(char __user *, struct kstat *);
1569 extern int vfs_lstat(char __user *, struct kstat *);
1570 extern int vfs_fstat(unsigned int, struct kstat *);
1571 
1572 extern int vfs_ioctl(struct file *, unsigned int, unsigned int, unsigned long);
1573 
1574 extern struct file_system_type *get_fs_type(const char *name);
1575 extern struct super_block *get_super(struct block_device *);
1576 extern struct super_block *user_get_super(dev_t);
1577 extern void drop_super(struct super_block *sb);
1578 
1579 extern int dcache_dir_open(struct inode *, struct file *);
1580 extern int dcache_dir_close(struct inode *, struct file *);
1581 extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
1582 extern int dcache_readdir(struct file *, void *, filldir_t);
1583 extern int simple_getattr(struct vfsmount *, struct dentry *, struct kstat *);
1584 extern int simple_statfs(struct super_block *, struct kstatfs *);
1585 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
1586 extern int simple_unlink(struct inode *, struct dentry *);
1587 extern int simple_rmdir(struct inode *, struct dentry *);
1588 extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
1589 extern int simple_sync_file(struct file *, struct dentry *, int);
1590 extern int simple_empty(struct dentry *);
1591 extern int simple_readpage(struct file *file, struct page *page);
1592 extern int simple_prepare_write(struct file *file, struct page *page,
1593 			unsigned offset, unsigned to);
1594 extern int simple_commit_write(struct file *file, struct page *page,
1595 				unsigned offset, unsigned to);
1596 
1597 extern struct dentry *simple_lookup(struct inode *, struct dentry *, struct nameidata *);
1598 extern ssize_t generic_read_dir(struct file *, char __user *, size_t, loff_t *);
1599 extern struct file_operations simple_dir_operations;
1600 extern struct inode_operations simple_dir_inode_operations;
1601 struct tree_descr { char *name; struct file_operations *ops; int mode; };
1602 struct dentry *d_alloc_name(struct dentry *, const char *);
1603 extern int simple_fill_super(struct super_block *, int, struct tree_descr *);
1604 extern int simple_pin_fs(char *name, struct vfsmount **mount, int *count);
1605 extern void simple_release_fs(struct vfsmount **mount, int *count);
1606 
1607 extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t);
1608 
1609 extern int inode_change_ok(struct inode *, struct iattr *);
1610 extern int __must_check inode_setattr(struct inode *, struct iattr *);
1611 
1612 extern void inode_update_time(struct inode *inode, int ctime_too);
1613 
1614 static inline ino_t parent_ino(struct dentry *dentry)
1615 {
1616 	ino_t res;
1617 
1618 	spin_lock(&dentry->d_lock);
1619 	res = dentry->d_parent->d_inode->i_ino;
1620 	spin_unlock(&dentry->d_lock);
1621 	return res;
1622 }
1623 
1624 /* kernel/fork.c */
1625 extern int unshare_files(void);
1626 
1627 /* Transaction based IO helpers */
1628 
1629 /*
1630  * An argresp is stored in an allocated page and holds the
1631  * size of the argument or response, along with its content
1632  */
1633 struct simple_transaction_argresp {
1634 	ssize_t size;
1635 	char data[0];
1636 };
1637 
1638 #define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))
1639 
1640 char *simple_transaction_get(struct file *file, const char __user *buf,
1641 				size_t size);
1642 ssize_t simple_transaction_read(struct file *file, char __user *buf,
1643 				size_t size, loff_t *pos);
1644 int simple_transaction_release(struct inode *inode, struct file *file);
1645 
1646 static inline void simple_transaction_set(struct file *file, size_t n)
1647 {
1648 	struct simple_transaction_argresp *ar = file->private_data;
1649 
1650 	BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
1651 
1652 	/*
1653 	 * The barrier ensures that ar->size will really remain zero until
1654 	 * ar->data is ready for reading.
1655 	 */
1656 	smp_mb();
1657 	ar->size = n;
1658 }
1659 
1660 #ifdef CONFIG_SECURITY
1661 static inline char *alloc_secdata(void)
1662 {
1663 	return (char *)get_zeroed_page(GFP_KERNEL);
1664 }
1665 
1666 static inline void free_secdata(void *secdata)
1667 {
1668 	free_page((unsigned long)secdata);
1669 }
1670 #else
1671 static inline char *alloc_secdata(void)
1672 {
1673 	return (char *)1;
1674 }
1675 
1676 static inline void free_secdata(void *secdata)
1677 { }
1678 #endif	/* CONFIG_SECURITY */
1679 
1680 #endif /* __KERNEL__ */
1681 #endif /* _LINUX_FS_H */
1682