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/fs/xfs/xfs_dir2_format.h

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C Header | 597 lines | 266 code | 64 blank | 267 comment | 1 complexity | 8141ea2dcc1101b8b363b01619521bf6 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 * Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
  3 * All Rights Reserved.
  4 *
  5 * This program is free software; you can redistribute it and/or
  6 * modify it under the terms of the GNU General Public License as
  7 * published by the Free Software Foundation.
  8 *
  9 * This program is distributed in the hope that it would be useful,
 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12 * GNU General Public License for more details.
 13 *
 14 * You should have received a copy of the GNU General Public License
 15 * along with this program; if not, write the Free Software Foundation,
 16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 17 */
 18#ifndef __XFS_DIR2_FORMAT_H__
 19#define __XFS_DIR2_FORMAT_H__
 20
 21/*
 22 * Directory version 2.
 23 *
 24 * There are 4 possible formats:
 25 *  - shortform - embedded into the inode
 26 *  - single block - data with embedded leaf at the end
 27 *  - multiple data blocks, single leaf+freeindex block
 28 *  - data blocks, node and leaf blocks (btree), freeindex blocks
 29 *
 30 * Note: many node blocks structures and constants are shared with the attr
 31 * code and defined in xfs_da_btree.h.
 32 */
 33
 34#define	XFS_DIR2_BLOCK_MAGIC	0x58443242	/* XD2B: single block dirs */
 35#define	XFS_DIR2_DATA_MAGIC	0x58443244	/* XD2D: multiblock dirs */
 36#define	XFS_DIR2_FREE_MAGIC	0x58443246	/* XD2F: free index blocks */
 37
 38/*
 39 * Byte offset in data block and shortform entry.
 40 */
 41typedef	__uint16_t	xfs_dir2_data_off_t;
 42#define	NULLDATAOFF	0xffffU
 43typedef uint		xfs_dir2_data_aoff_t;	/* argument form */
 44
 45/*
 46 * Normalized offset (in a data block) of the entry, really xfs_dir2_data_off_t.
 47 * Only need 16 bits, this is the byte offset into the single block form.
 48 */
 49typedef struct { __uint8_t i[2]; } __arch_pack xfs_dir2_sf_off_t;
 50
 51/*
 52 * Offset in data space of a data entry.
 53 */
 54typedef	__uint32_t	xfs_dir2_dataptr_t;
 55#define	XFS_DIR2_MAX_DATAPTR	((xfs_dir2_dataptr_t)0xffffffff)
 56#define	XFS_DIR2_NULL_DATAPTR	((xfs_dir2_dataptr_t)0)
 57
 58/*
 59 * Byte offset in a directory.
 60 */
 61typedef	xfs_off_t	xfs_dir2_off_t;
 62
 63/*
 64 * Directory block number (logical dirblk in file)
 65 */
 66typedef	__uint32_t	xfs_dir2_db_t;
 67
 68/*
 69 * Inode number stored as 8 8-bit values.
 70 */
 71typedef	struct { __uint8_t i[8]; } xfs_dir2_ino8_t;
 72
 73/*
 74 * Inode number stored as 4 8-bit values.
 75 * Works a lot of the time, when all the inode numbers in a directory
 76 * fit in 32 bits.
 77 */
 78typedef struct { __uint8_t i[4]; } xfs_dir2_ino4_t;
 79
 80typedef union {
 81	xfs_dir2_ino8_t	i8;
 82	xfs_dir2_ino4_t	i4;
 83} xfs_dir2_inou_t;
 84#define	XFS_DIR2_MAX_SHORT_INUM	((xfs_ino_t)0xffffffffULL)
 85
 86/*
 87 * Directory layout when stored internal to an inode.
 88 *
 89 * Small directories are packed as tightly as possible so as to fit into the
 90 * literal area of the inode.  These "shortform" directories consist of a
 91 * single xfs_dir2_sf_hdr header followed by zero or more xfs_dir2_sf_entry
 92 * structures.  Due the different inode number storage size and the variable
 93 * length name field in the xfs_dir2_sf_entry all these structure are
 94 * variable length, and the accessors in this file should be used to iterate
 95 * over them.
 96 */
 97typedef struct xfs_dir2_sf_hdr {
 98	__uint8_t		count;		/* count of entries */
 99	__uint8_t		i8count;	/* count of 8-byte inode #s */
100	xfs_dir2_inou_t		parent;		/* parent dir inode number */
101} __arch_pack xfs_dir2_sf_hdr_t;
102
103typedef struct xfs_dir2_sf_entry {
104	__u8			namelen;	/* actual name length */
105	xfs_dir2_sf_off_t	offset;		/* saved offset */
106	__u8			name[];		/* name, variable size */
107	/*
108	 * A xfs_dir2_ino8_t or xfs_dir2_ino4_t follows here, at a
109	 * variable offset after the name.
110	 */
111} __arch_pack xfs_dir2_sf_entry_t;
112
113static inline int xfs_dir2_sf_hdr_size(int i8count)
114{
115	return sizeof(struct xfs_dir2_sf_hdr) -
116		(i8count == 0) *
117		(sizeof(xfs_dir2_ino8_t) - sizeof(xfs_dir2_ino4_t));
118}
119
120static inline xfs_dir2_data_aoff_t
121xfs_dir2_sf_get_offset(xfs_dir2_sf_entry_t *sfep)
122{
123	return get_unaligned_be16(&sfep->offset.i);
124}
125
126static inline void
127xfs_dir2_sf_put_offset(xfs_dir2_sf_entry_t *sfep, xfs_dir2_data_aoff_t off)
128{
129	put_unaligned_be16(off, &sfep->offset.i);
130}
131
132static inline int
133xfs_dir2_sf_entsize(struct xfs_dir2_sf_hdr *hdr, int len)
134{
135	return sizeof(struct xfs_dir2_sf_entry) +	/* namelen + offset */
136		len +					/* name */
137		(hdr->i8count ?				/* ino */
138		 sizeof(xfs_dir2_ino8_t) :
139		 sizeof(xfs_dir2_ino4_t));
140}
141
142static inline struct xfs_dir2_sf_entry *
143xfs_dir2_sf_firstentry(struct xfs_dir2_sf_hdr *hdr)
144{
145	return (struct xfs_dir2_sf_entry *)
146		((char *)hdr + xfs_dir2_sf_hdr_size(hdr->i8count));
147}
148
149static inline struct xfs_dir2_sf_entry *
150xfs_dir2_sf_nextentry(struct xfs_dir2_sf_hdr *hdr,
151		struct xfs_dir2_sf_entry *sfep)
152{
153	return (struct xfs_dir2_sf_entry *)
154		((char *)sfep + xfs_dir2_sf_entsize(hdr, sfep->namelen));
155}
156
157
158/*
159 * Data block structures.
160 *
161 * A pure data block looks like the following drawing on disk:
162 *
163 *    +-------------------------------------------------+
164 *    | xfs_dir2_data_hdr_t                             |
165 *    +-------------------------------------------------+
166 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
167 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
168 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
169 *    | ...                                             |
170 *    +-------------------------------------------------+
171 *    | unused space                                    |
172 *    +-------------------------------------------------+
173 *
174 * As all the entries are variable size structures the accessors below should
175 * be used to iterate over them.
176 *
177 * In addition to the pure data blocks for the data and node formats,
178 * most structures are also used for the combined data/freespace "block"
179 * format below.
180 */
181
182#define	XFS_DIR2_DATA_ALIGN_LOG	3		/* i.e., 8 bytes */
183#define	XFS_DIR2_DATA_ALIGN	(1 << XFS_DIR2_DATA_ALIGN_LOG)
184#define	XFS_DIR2_DATA_FREE_TAG	0xffff
185#define	XFS_DIR2_DATA_FD_COUNT	3
186
187/*
188 * Directory address space divided into sections,
189 * spaces separated by 32GB.
190 */
191#define	XFS_DIR2_SPACE_SIZE	(1ULL << (32 + XFS_DIR2_DATA_ALIGN_LOG))
192#define	XFS_DIR2_DATA_SPACE	0
193#define	XFS_DIR2_DATA_OFFSET	(XFS_DIR2_DATA_SPACE * XFS_DIR2_SPACE_SIZE)
194#define	XFS_DIR2_DATA_FIRSTDB(mp)	\
195	xfs_dir2_byte_to_db(mp, XFS_DIR2_DATA_OFFSET)
196
197/*
198 * Offsets of . and .. in data space (always block 0)
199 */
200#define	XFS_DIR2_DATA_DOT_OFFSET	\
201	((xfs_dir2_data_aoff_t)sizeof(struct xfs_dir2_data_hdr))
202#define	XFS_DIR2_DATA_DOTDOT_OFFSET	\
203	(XFS_DIR2_DATA_DOT_OFFSET + xfs_dir2_data_entsize(1))
204#define	XFS_DIR2_DATA_FIRST_OFFSET		\
205	(XFS_DIR2_DATA_DOTDOT_OFFSET + xfs_dir2_data_entsize(2))
206
207/*
208 * Describe a free area in the data block.
209 *
210 * The freespace will be formatted as a xfs_dir2_data_unused_t.
211 */
212typedef struct xfs_dir2_data_free {
213	__be16			offset;		/* start of freespace */
214	__be16			length;		/* length of freespace */
215} xfs_dir2_data_free_t;
216
217/*
218 * Header for the data blocks.
219 *
220 * The code knows that XFS_DIR2_DATA_FD_COUNT is 3.
221 */
222typedef struct xfs_dir2_data_hdr {
223	__be32			magic;		/* XFS_DIR2_DATA_MAGIC or */
224						/* XFS_DIR2_BLOCK_MAGIC */
225	xfs_dir2_data_free_t	bestfree[XFS_DIR2_DATA_FD_COUNT];
226} xfs_dir2_data_hdr_t;
227
228/*
229 * Active entry in a data block.
230 *
231 * Aligned to 8 bytes.  After the variable length name field there is a
232 * 2 byte tag field, which can be accessed using xfs_dir2_data_entry_tag_p.
233 */
234typedef struct xfs_dir2_data_entry {
235	__be64			inumber;	/* inode number */
236	__u8			namelen;	/* name length */
237	__u8			name[];		/* name bytes, no null */
238     /*	__be16                  tag; */		/* starting offset of us */
239} xfs_dir2_data_entry_t;
240
241/*
242 * Unused entry in a data block.
243 *
244 * Aligned to 8 bytes.  Tag appears as the last 2 bytes and must be accessed
245 * using xfs_dir2_data_unused_tag_p.
246 */
247typedef struct xfs_dir2_data_unused {
248	__be16			freetag;	/* XFS_DIR2_DATA_FREE_TAG */
249	__be16			length;		/* total free length */
250						/* variable offset */
251	__be16			tag;		/* starting offset of us */
252} xfs_dir2_data_unused_t;
253
254/*
255 * Size of a data entry.
256 */
257static inline int xfs_dir2_data_entsize(int n)
258{
259	return (int)roundup(offsetof(struct xfs_dir2_data_entry, name[0]) + n +
260		 (uint)sizeof(xfs_dir2_data_off_t), XFS_DIR2_DATA_ALIGN);
261}
262
263/*
264 * Pointer to an entry's tag word.
265 */
266static inline __be16 *
267xfs_dir2_data_entry_tag_p(struct xfs_dir2_data_entry *dep)
268{
269	return (__be16 *)((char *)dep +
270		xfs_dir2_data_entsize(dep->namelen) - sizeof(__be16));
271}
272
273/*
274 * Pointer to a freespace's tag word.
275 */
276static inline __be16 *
277xfs_dir2_data_unused_tag_p(struct xfs_dir2_data_unused *dup)
278{
279	return (__be16 *)((char *)dup +
280			be16_to_cpu(dup->length) - sizeof(__be16));
281}
282
283/*
284 * Leaf block structures.
285 *
286 * A pure leaf block looks like the following drawing on disk:
287 *
288 *    +---------------------------+
289 *    | xfs_dir2_leaf_hdr_t       |
290 *    +---------------------------+
291 *    | xfs_dir2_leaf_entry_t     |
292 *    | xfs_dir2_leaf_entry_t     |
293 *    | xfs_dir2_leaf_entry_t     |
294 *    | xfs_dir2_leaf_entry_t     |
295 *    | ...                       |
296 *    +---------------------------+
297 *    | xfs_dir2_data_off_t       |
298 *    | xfs_dir2_data_off_t       |
299 *    | xfs_dir2_data_off_t       |
300 *    | ...                       |
301 *    +---------------------------+
302 *    | xfs_dir2_leaf_tail_t      |
303 *    +---------------------------+
304 *
305 * The xfs_dir2_data_off_t members (bests) and tail are at the end of the block
306 * for single-leaf (magic = XFS_DIR2_LEAF1_MAGIC) blocks only, but not present
307 * for directories with separate leaf nodes and free space blocks
308 * (magic = XFS_DIR2_LEAFN_MAGIC).
309 *
310 * As all the entries are variable size structures the accessors below should
311 * be used to iterate over them.
312 */
313
314/*
315 * Offset of the leaf/node space.  First block in this space
316 * is the btree root.
317 */
318#define	XFS_DIR2_LEAF_SPACE	1
319#define	XFS_DIR2_LEAF_OFFSET	(XFS_DIR2_LEAF_SPACE * XFS_DIR2_SPACE_SIZE)
320#define	XFS_DIR2_LEAF_FIRSTDB(mp)	\
321	xfs_dir2_byte_to_db(mp, XFS_DIR2_LEAF_OFFSET)
322
323/*
324 * Leaf block header.
325 */
326typedef struct xfs_dir2_leaf_hdr {
327	xfs_da_blkinfo_t	info;		/* header for da routines */
328	__be16			count;		/* count of entries */
329	__be16			stale;		/* count of stale entries */
330} xfs_dir2_leaf_hdr_t;
331
332/*
333 * Leaf block entry.
334 */
335typedef struct xfs_dir2_leaf_entry {
336	__be32			hashval;	/* hash value of name */
337	__be32			address;	/* address of data entry */
338} xfs_dir2_leaf_entry_t;
339
340/*
341 * Leaf block tail.
342 */
343typedef struct xfs_dir2_leaf_tail {
344	__be32			bestcount;
345} xfs_dir2_leaf_tail_t;
346
347/*
348 * Leaf block.
349 */
350typedef struct xfs_dir2_leaf {
351	xfs_dir2_leaf_hdr_t	hdr;		/* leaf header */
352	xfs_dir2_leaf_entry_t	ents[];		/* entries */
353} xfs_dir2_leaf_t;
354
355/*
356 * DB blocks here are logical directory block numbers, not filesystem blocks.
357 */
358
359static inline int xfs_dir2_max_leaf_ents(struct xfs_mount *mp)
360{
361	return (mp->m_dirblksize - (uint)sizeof(struct xfs_dir2_leaf_hdr)) /
362		(uint)sizeof(struct xfs_dir2_leaf_entry);
363}
364
365/*
366 * Get address of the bestcount field in the single-leaf block.
367 */
368static inline struct xfs_dir2_leaf_tail *
369xfs_dir2_leaf_tail_p(struct xfs_mount *mp, struct xfs_dir2_leaf *lp)
370{
371	return (struct xfs_dir2_leaf_tail *)
372		((char *)lp + mp->m_dirblksize -
373		  sizeof(struct xfs_dir2_leaf_tail));
374}
375
376/*
377 * Get address of the bests array in the single-leaf block.
378 */
379static inline __be16 *
380xfs_dir2_leaf_bests_p(struct xfs_dir2_leaf_tail *ltp)
381{
382	return (__be16 *)ltp - be32_to_cpu(ltp->bestcount);
383}
384
385/*
386 * Convert dataptr to byte in file space
387 */
388static inline xfs_dir2_off_t
389xfs_dir2_dataptr_to_byte(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
390{
391	return (xfs_dir2_off_t)dp << XFS_DIR2_DATA_ALIGN_LOG;
392}
393
394/*
395 * Convert byte in file space to dataptr.  It had better be aligned.
396 */
397static inline xfs_dir2_dataptr_t
398xfs_dir2_byte_to_dataptr(struct xfs_mount *mp, xfs_dir2_off_t by)
399{
400	return (xfs_dir2_dataptr_t)(by >> XFS_DIR2_DATA_ALIGN_LOG);
401}
402
403/*
404 * Convert byte in space to (DB) block
405 */
406static inline xfs_dir2_db_t
407xfs_dir2_byte_to_db(struct xfs_mount *mp, xfs_dir2_off_t by)
408{
409	return (xfs_dir2_db_t)
410		(by >> (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog));
411}
412
413/*
414 * Convert dataptr to a block number
415 */
416static inline xfs_dir2_db_t
417xfs_dir2_dataptr_to_db(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
418{
419	return xfs_dir2_byte_to_db(mp, xfs_dir2_dataptr_to_byte(mp, dp));
420}
421
422/*
423 * Convert byte in space to offset in a block
424 */
425static inline xfs_dir2_data_aoff_t
426xfs_dir2_byte_to_off(struct xfs_mount *mp, xfs_dir2_off_t by)
427{
428	return (xfs_dir2_data_aoff_t)(by &
429		((1 << (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog)) - 1));
430}
431
432/*
433 * Convert dataptr to a byte offset in a block
434 */
435static inline xfs_dir2_data_aoff_t
436xfs_dir2_dataptr_to_off(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
437{
438	return xfs_dir2_byte_to_off(mp, xfs_dir2_dataptr_to_byte(mp, dp));
439}
440
441/*
442 * Convert block and offset to byte in space
443 */
444static inline xfs_dir2_off_t
445xfs_dir2_db_off_to_byte(struct xfs_mount *mp, xfs_dir2_db_t db,
446			xfs_dir2_data_aoff_t o)
447{
448	return ((xfs_dir2_off_t)db <<
449		(mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog)) + o;
450}
451
452/*
453 * Convert block (DB) to block (dablk)
454 */
455static inline xfs_dablk_t
456xfs_dir2_db_to_da(struct xfs_mount *mp, xfs_dir2_db_t db)
457{
458	return (xfs_dablk_t)(db << mp->m_sb.sb_dirblklog);
459}
460
461/*
462 * Convert byte in space to (DA) block
463 */
464static inline xfs_dablk_t
465xfs_dir2_byte_to_da(struct xfs_mount *mp, xfs_dir2_off_t by)
466{
467	return xfs_dir2_db_to_da(mp, xfs_dir2_byte_to_db(mp, by));
468}
469
470/*
471 * Convert block and offset to dataptr
472 */
473static inline xfs_dir2_dataptr_t
474xfs_dir2_db_off_to_dataptr(struct xfs_mount *mp, xfs_dir2_db_t db,
475			   xfs_dir2_data_aoff_t o)
476{
477	return xfs_dir2_byte_to_dataptr(mp, xfs_dir2_db_off_to_byte(mp, db, o));
478}
479
480/*
481 * Convert block (dablk) to block (DB)
482 */
483static inline xfs_dir2_db_t
484xfs_dir2_da_to_db(struct xfs_mount *mp, xfs_dablk_t da)
485{
486	return (xfs_dir2_db_t)(da >> mp->m_sb.sb_dirblklog);
487}
488
489/*
490 * Convert block (dablk) to byte offset in space
491 */
492static inline xfs_dir2_off_t
493xfs_dir2_da_to_byte(struct xfs_mount *mp, xfs_dablk_t da)
494{
495	return xfs_dir2_db_off_to_byte(mp, xfs_dir2_da_to_db(mp, da), 0);
496}
497
498/*
499 * Free space block defintions for the node format.
500 */
501
502/*
503 * Offset of the freespace index.
504 */
505#define	XFS_DIR2_FREE_SPACE	2
506#define	XFS_DIR2_FREE_OFFSET	(XFS_DIR2_FREE_SPACE * XFS_DIR2_SPACE_SIZE)
507#define	XFS_DIR2_FREE_FIRSTDB(mp)	\
508	xfs_dir2_byte_to_db(mp, XFS_DIR2_FREE_OFFSET)
509
510typedef	struct xfs_dir2_free_hdr {
511	__be32			magic;		/* XFS_DIR2_FREE_MAGIC */
512	__be32			firstdb;	/* db of first entry */
513	__be32			nvalid;		/* count of valid entries */
514	__be32			nused;		/* count of used entries */
515} xfs_dir2_free_hdr_t;
516
517typedef struct xfs_dir2_free {
518	xfs_dir2_free_hdr_t	hdr;		/* block header */
519	__be16			bests[];	/* best free counts */
520						/* unused entries are -1 */
521} xfs_dir2_free_t;
522
523static inline int xfs_dir2_free_max_bests(struct xfs_mount *mp)
524{
525	return (mp->m_dirblksize - sizeof(struct xfs_dir2_free_hdr)) /
526		sizeof(xfs_dir2_data_off_t);
527}
528
529/*
530 * Convert data space db to the corresponding free db.
531 */
532static inline xfs_dir2_db_t
533xfs_dir2_db_to_fdb(struct xfs_mount *mp, xfs_dir2_db_t db)
534{
535	return XFS_DIR2_FREE_FIRSTDB(mp) + db / xfs_dir2_free_max_bests(mp);
536}
537
538/*
539 * Convert data space db to the corresponding index in a free db.
540 */
541static inline int
542xfs_dir2_db_to_fdindex(struct xfs_mount *mp, xfs_dir2_db_t db)
543{
544	return db % xfs_dir2_free_max_bests(mp);
545}
546
547/*
548 * Single block format.
549 *
550 * The single block format looks like the following drawing on disk:
551 *
552 *    +-------------------------------------------------+
553 *    | xfs_dir2_data_hdr_t                             |
554 *    +-------------------------------------------------+
555 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
556 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
557 *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t :
558 *    | ...                                             |
559 *    +-------------------------------------------------+
560 *    | unused space                                    |
561 *    +-------------------------------------------------+
562 *    | ...                                             |
563 *    | xfs_dir2_leaf_entry_t                           |
564 *    | xfs_dir2_leaf_entry_t                           |
565 *    +-------------------------------------------------+
566 *    | xfs_dir2_block_tail_t                           |
567 *    +-------------------------------------------------+
568 *
569 * As all the entries are variable size structures the accessors below should
570 * be used to iterate over them.
571 */
572
573typedef struct xfs_dir2_block_tail {
574	__be32		count;			/* count of leaf entries */
575	__be32		stale;			/* count of stale lf entries */
576} xfs_dir2_block_tail_t;
577
578/*
579 * Pointer to the leaf header embedded in a data block (1-block format)
580 */
581static inline struct xfs_dir2_block_tail *
582xfs_dir2_block_tail_p(struct xfs_mount *mp, struct xfs_dir2_data_hdr *hdr)
583{
584	return ((struct xfs_dir2_block_tail *)
585		((char *)hdr + mp->m_dirblksize)) - 1;
586}
587
588/*
589 * Pointer to the leaf entries embedded in a data block (1-block format)
590 */
591static inline struct xfs_dir2_leaf_entry *
592xfs_dir2_block_leaf_p(struct xfs_dir2_block_tail *btp)
593{
594	return ((struct xfs_dir2_leaf_entry *)btp) - be32_to_cpu(btp->count);
595}
596
597#endif /* __XFS_DIR2_FORMAT_H__ */