xref: /linux/fs/xfs/libxfs/xfs_da_format.h (revision c02ce1735b150cf7c3b43790b48e23dcd17c0d46)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
4  * Copyright (c) 2013 Red Hat, Inc.
5  * All Rights Reserved.
6  */
7 #ifndef __XFS_DA_FORMAT_H__
8 #define __XFS_DA_FORMAT_H__
9 
10 /*
11  * This structure is common to both leaf nodes and non-leaf nodes in the Btree.
12  *
13  * It is used to manage a doubly linked list of all blocks at the same
14  * level in the Btree, and to identify which type of block this is.
15  */
16 #define XFS_DA_NODE_MAGIC	0xfebe	/* magic number: non-leaf blocks */
17 #define XFS_ATTR_LEAF_MAGIC	0xfbee	/* magic number: attribute leaf blks */
18 #define XFS_DIR2_LEAF1_MAGIC	0xd2f1	/* magic number: v2 dirlf single blks */
19 #define XFS_DIR2_LEAFN_MAGIC	0xd2ff	/* magic number: v2 dirlf multi blks */
20 
21 typedef struct xfs_da_blkinfo {
22 	__be32		forw;			/* previous block in list */
23 	__be32		back;			/* following block in list */
24 	__be16		magic;			/* validity check on block */
25 	__be16		pad;			/* unused */
26 } xfs_da_blkinfo_t;
27 
28 /*
29  * CRC enabled directory structure types
30  *
31  * The headers change size for the additional verification information, but
32  * otherwise the tree layouts and contents are unchanged. Hence the da btree
33  * code can use the struct xfs_da_blkinfo for manipulating the tree links and
34  * magic numbers without modification for both v2 and v3 nodes.
35  */
36 #define XFS_DA3_NODE_MAGIC	0x3ebe	/* magic number: non-leaf blocks */
37 #define XFS_ATTR3_LEAF_MAGIC	0x3bee	/* magic number: attribute leaf blks */
38 #define XFS_DIR3_LEAF1_MAGIC	0x3df1	/* magic number: v3 dirlf single blks */
39 #define XFS_DIR3_LEAFN_MAGIC	0x3dff	/* magic number: v3 dirlf multi blks */
40 
41 struct xfs_da3_blkinfo {
42 	/*
43 	 * the node link manipulation code relies on the fact that the first
44 	 * element of this structure is the struct xfs_da_blkinfo so it can
45 	 * ignore the differences in the rest of the structures.
46 	 */
47 	struct xfs_da_blkinfo	hdr;
48 	__be32			crc;	/* CRC of block */
49 	__be64			blkno;	/* first block of the buffer */
50 	__be64			lsn;	/* sequence number of last write */
51 	uuid_t			uuid;	/* filesystem we belong to */
52 	__be64			owner;	/* inode that owns the block */
53 };
54 
55 /*
56  * This is the structure of the root and intermediate nodes in the Btree.
57  * The leaf nodes are defined above.
58  *
59  * Entries are not packed.
60  *
61  * Since we have duplicate keys, use a binary search but always follow
62  * all match in the block, not just the first match found.
63  */
64 #define XFS_DA_NODE_MAXDEPTH	5	/* max depth of Btree */
65 
66 typedef struct xfs_da_node_hdr {
67 	struct xfs_da_blkinfo	info;	/* block type, links, etc. */
68 	__be16			__count; /* count of active entries */
69 	__be16			__level; /* level above leaves (leaf == 0) */
70 } xfs_da_node_hdr_t;
71 
72 struct xfs_da3_node_hdr {
73 	struct xfs_da3_blkinfo	info;	/* block type, links, etc. */
74 	__be16			__count; /* count of active entries */
75 	__be16			__level; /* level above leaves (leaf == 0) */
76 	__be32			__pad32;
77 };
78 
79 #define XFS_DA3_NODE_CRC_OFF	(offsetof(struct xfs_da3_node_hdr, info.crc))
80 
81 typedef struct xfs_da_node_entry {
82 	__be32	hashval;	/* hash value for this descendant */
83 	__be32	before;		/* Btree block before this key */
84 } xfs_da_node_entry_t;
85 
86 typedef struct xfs_da_intnode {
87 	struct xfs_da_node_hdr	hdr;
88 	struct xfs_da_node_entry __btree[];
89 } xfs_da_intnode_t;
90 
91 struct xfs_da3_intnode {
92 	struct xfs_da3_node_hdr	hdr;
93 	struct xfs_da_node_entry __btree[];
94 };
95 
96 /*
97  * Directory version 2.
98  *
99  * There are 4 possible formats:
100  *  - shortform - embedded into the inode
101  *  - single block - data with embedded leaf at the end
102  *  - multiple data blocks, single leaf+freeindex block
103  *  - data blocks, node and leaf blocks (btree), freeindex blocks
104  *
105  * Note: many node blocks structures and constants are shared with the attr
106  * code and defined in xfs_da_btree.h.
107  */
108 
109 #define	XFS_DIR2_BLOCK_MAGIC	0x58443242	/* XD2B: single block dirs */
110 #define	XFS_DIR2_DATA_MAGIC	0x58443244	/* XD2D: multiblock dirs */
111 #define	XFS_DIR2_FREE_MAGIC	0x58443246	/* XD2F: free index blocks */
112 
113 /*
114  * Directory Version 3 With CRCs.
115  *
116  * The tree formats are the same as for version 2 directories.  The difference
117  * is in the block header and dirent formats. In many cases the v3 structures
118  * use v2 definitions as they are no different and this makes code sharing much
119  * easier.
120  *
121  * Also, the xfs_dir3_*() functions handle both v2 and v3 formats - if the
122  * format is v2 then they switch to the existing v2 code, or the format is v3
123  * they implement the v3 functionality. This means the existing dir2 is a mix of
124  * xfs_dir2/xfs_dir3 calls and functions. The xfs_dir3 functions are called
125  * where there is a difference in the formats, otherwise the code is unchanged.
126  *
127  * Where it is possible, the code decides what to do based on the magic numbers
128  * in the blocks rather than feature bits in the superblock. This means the code
129  * is as independent of the external XFS code as possible as doesn't require
130  * passing struct xfs_mount pointers into places where it isn't really
131  * necessary.
132  *
133  * Version 3 includes:
134  *
135  *	- a larger block header for CRC and identification purposes and so the
136  *	offsets of all the structures inside the blocks are different.
137  *
138  *	- new magic numbers to be able to detect the v2/v3 types on the fly.
139  */
140 
141 #define	XFS_DIR3_BLOCK_MAGIC	0x58444233	/* XDB3: single block dirs */
142 #define	XFS_DIR3_DATA_MAGIC	0x58444433	/* XDD3: multiblock dirs */
143 #define	XFS_DIR3_FREE_MAGIC	0x58444633	/* XDF3: free index blocks */
144 
145 /*
146  * Dirents in version 3 directories have a file type field. Additions to this
147  * list are an on-disk format change, requiring feature bits. Valid values
148  * are as follows:
149  */
150 #define XFS_DIR3_FT_UNKNOWN		0
151 #define XFS_DIR3_FT_REG_FILE		1
152 #define XFS_DIR3_FT_DIR			2
153 #define XFS_DIR3_FT_CHRDEV		3
154 #define XFS_DIR3_FT_BLKDEV		4
155 #define XFS_DIR3_FT_FIFO		5
156 #define XFS_DIR3_FT_SOCK		6
157 #define XFS_DIR3_FT_SYMLINK		7
158 #define XFS_DIR3_FT_WHT			8
159 
160 #define XFS_DIR3_FT_MAX			9
161 
162 #define XFS_DIR3_FTYPE_STR \
163 	{ XFS_DIR3_FT_UNKNOWN,	"unknown" }, \
164 	{ XFS_DIR3_FT_REG_FILE,	"file" }, \
165 	{ XFS_DIR3_FT_DIR,	"directory" }, \
166 	{ XFS_DIR3_FT_CHRDEV,	"char" }, \
167 	{ XFS_DIR3_FT_BLKDEV,	"block" }, \
168 	{ XFS_DIR3_FT_FIFO,	"fifo" }, \
169 	{ XFS_DIR3_FT_SOCK,	"sock" }, \
170 	{ XFS_DIR3_FT_SYMLINK,	"symlink" }, \
171 	{ XFS_DIR3_FT_WHT,	"whiteout" }
172 
173 /*
174  * Byte offset in data block and shortform entry.
175  */
176 typedef uint16_t	xfs_dir2_data_off_t;
177 #define	NULLDATAOFF	0xffffU
178 typedef uint		xfs_dir2_data_aoff_t;	/* argument form */
179 
180 /*
181  * Offset in data space of a data entry.
182  */
183 typedef uint32_t	xfs_dir2_dataptr_t;
184 #define	XFS_DIR2_MAX_DATAPTR	((xfs_dir2_dataptr_t)0xffffffff)
185 #define	XFS_DIR2_NULL_DATAPTR	((xfs_dir2_dataptr_t)0)
186 
187 /*
188  * Byte offset in a directory.
189  */
190 typedef	xfs_off_t	xfs_dir2_off_t;
191 
192 /*
193  * Directory block number (logical dirblk in file)
194  */
195 typedef uint32_t	xfs_dir2_db_t;
196 
197 #define XFS_INO32_SIZE	4
198 #define XFS_INO64_SIZE	8
199 #define XFS_INO64_DIFF	(XFS_INO64_SIZE - XFS_INO32_SIZE)
200 
201 #define	XFS_DIR2_MAX_SHORT_INUM	((xfs_ino_t)0xffffffffULL)
202 
203 /*
204  * Directory layout when stored internal to an inode.
205  *
206  * Small directories are packed as tightly as possible so as to fit into the
207  * literal area of the inode.  These "shortform" directories consist of a
208  * single xfs_dir2_sf_hdr header followed by zero or more xfs_dir2_sf_entry
209  * structures.  Due the different inode number storage size and the variable
210  * length name field in the xfs_dir2_sf_entry all these structure are
211  * variable length, and the accessors in this file should be used to iterate
212  * over them.
213  */
214 typedef struct xfs_dir2_sf_hdr {
215 	uint8_t			count;		/* count of entries */
216 	uint8_t			i8count;	/* count of 8-byte inode #s */
217 	uint8_t			parent[8];	/* parent dir inode number */
218 } __packed xfs_dir2_sf_hdr_t;
219 
220 typedef struct xfs_dir2_sf_entry {
221 	__u8			namelen;	/* actual name length */
222 	__u8			offset[2];	/* saved offset */
223 	__u8			name[];		/* name, variable size */
224 	/*
225 	 * A single byte containing the file type field follows the inode
226 	 * number for version 3 directory entries.
227 	 *
228 	 * A 64-bit or 32-bit inode number follows here, at a variable offset
229 	 * after the name.
230 	 */
231 } __packed xfs_dir2_sf_entry_t;
232 
233 static inline int xfs_dir2_sf_hdr_size(int i8count)
234 {
235 	return sizeof(struct xfs_dir2_sf_hdr) -
236 		(i8count == 0) * XFS_INO64_DIFF;
237 }
238 
239 static inline xfs_dir2_data_aoff_t
240 xfs_dir2_sf_get_offset(xfs_dir2_sf_entry_t *sfep)
241 {
242 	return get_unaligned_be16(sfep->offset);
243 }
244 
245 static inline void
246 xfs_dir2_sf_put_offset(xfs_dir2_sf_entry_t *sfep, xfs_dir2_data_aoff_t off)
247 {
248 	put_unaligned_be16(off, sfep->offset);
249 }
250 
251 static inline struct xfs_dir2_sf_entry *
252 xfs_dir2_sf_firstentry(struct xfs_dir2_sf_hdr *hdr)
253 {
254 	return (struct xfs_dir2_sf_entry *)
255 		((char *)hdr + xfs_dir2_sf_hdr_size(hdr->i8count));
256 }
257 
258 /*
259  * Data block structures.
260  *
261  * A pure data block looks like the following drawing on disk:
262  *
263  *    +-------------------------------------------------+
264  *    | xfs_dir2_data_hdr_t                             |
265  *    +-------------------------------------------------+
266  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
267  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
268  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
269  *    | ...                                             |
270  *    +-------------------------------------------------+
271  *    | unused space                                    |
272  *    +-------------------------------------------------+
273  *
274  * As all the entries are variable size structures the accessors below should
275  * be used to iterate over them.
276  *
277  * In addition to the pure data blocks for the data and node formats,
278  * most structures are also used for the combined data/freespace "block"
279  * format below.
280  */
281 
282 #define	XFS_DIR2_DATA_ALIGN_LOG	3		/* i.e., 8 bytes */
283 #define	XFS_DIR2_DATA_ALIGN	(1 << XFS_DIR2_DATA_ALIGN_LOG)
284 #define	XFS_DIR2_DATA_FREE_TAG	0xffff
285 #define	XFS_DIR2_DATA_FD_COUNT	3
286 
287 /*
288  * Directory address space divided into sections,
289  * spaces separated by 32GB.
290  */
291 #define	XFS_DIR2_MAX_SPACES	3
292 #define	XFS_DIR2_SPACE_SIZE	(1ULL << (32 + XFS_DIR2_DATA_ALIGN_LOG))
293 #define	XFS_DIR2_DATA_SPACE	0
294 #define	XFS_DIR2_DATA_OFFSET	(XFS_DIR2_DATA_SPACE * XFS_DIR2_SPACE_SIZE)
295 
296 /*
297  * Describe a free area in the data block.
298  *
299  * The freespace will be formatted as a xfs_dir2_data_unused_t.
300  */
301 typedef struct xfs_dir2_data_free {
302 	__be16			offset;		/* start of freespace */
303 	__be16			length;		/* length of freespace */
304 } xfs_dir2_data_free_t;
305 
306 /*
307  * Header for the data blocks.
308  *
309  * The code knows that XFS_DIR2_DATA_FD_COUNT is 3.
310  */
311 typedef struct xfs_dir2_data_hdr {
312 	__be32			magic;		/* XFS_DIR2_DATA_MAGIC or */
313 						/* XFS_DIR2_BLOCK_MAGIC */
314 	xfs_dir2_data_free_t	bestfree[XFS_DIR2_DATA_FD_COUNT];
315 } xfs_dir2_data_hdr_t;
316 
317 /*
318  * define a structure for all the verification fields we are adding to the
319  * directory block structures. This will be used in several structures.
320  * The magic number must be the first entry to align with all the dir2
321  * structures so we determine how to decode them just by the magic number.
322  */
323 struct xfs_dir3_blk_hdr {
324 	__be32			magic;	/* magic number */
325 	__be32			crc;	/* CRC of block */
326 	__be64			blkno;	/* first block of the buffer */
327 	__be64			lsn;	/* sequence number of last write */
328 	uuid_t			uuid;	/* filesystem we belong to */
329 	__be64			owner;	/* inode that owns the block */
330 };
331 
332 struct xfs_dir3_data_hdr {
333 	struct xfs_dir3_blk_hdr	hdr;
334 	xfs_dir2_data_free_t	best_free[XFS_DIR2_DATA_FD_COUNT];
335 	__be32			pad;	/* 64 bit alignment */
336 };
337 
338 #define XFS_DIR3_DATA_CRC_OFF  offsetof(struct xfs_dir3_data_hdr, hdr.crc)
339 
340 /*
341  * Active entry in a data block.
342  *
343  * Aligned to 8 bytes.  After the variable length name field there is a
344  * 2 byte tag field, which can be accessed using xfs_dir3_data_entry_tag_p.
345  *
346  * For dir3 structures, there is file type field between the name and the tag.
347  * This can only be manipulated by helper functions. It is packed hard against
348  * the end of the name so any padding for rounding is between the file type and
349  * the tag.
350  */
351 typedef struct xfs_dir2_data_entry {
352 	__be64			inumber;	/* inode number */
353 	__u8			namelen;	/* name length */
354 	__u8			name[];		/* name bytes, no null */
355      /* __u8			filetype; */	/* type of inode we point to */
356      /*	__be16                  tag; */		/* starting offset of us */
357 } xfs_dir2_data_entry_t;
358 
359 /*
360  * Unused entry in a data block.
361  *
362  * Aligned to 8 bytes.  Tag appears as the last 2 bytes and must be accessed
363  * using xfs_dir2_data_unused_tag_p.
364  */
365 typedef struct xfs_dir2_data_unused {
366 	__be16			freetag;	/* XFS_DIR2_DATA_FREE_TAG */
367 	__be16			length;		/* total free length */
368 						/* variable offset */
369 	__be16			tag;		/* starting offset of us */
370 } xfs_dir2_data_unused_t;
371 
372 /*
373  * Pointer to a freespace's tag word.
374  */
375 static inline __be16 *
376 xfs_dir2_data_unused_tag_p(struct xfs_dir2_data_unused *dup)
377 {
378 	return (__be16 *)((char *)dup +
379 			be16_to_cpu(dup->length) - sizeof(__be16));
380 }
381 
382 /*
383  * Leaf block structures.
384  *
385  * A pure leaf block looks like the following drawing on disk:
386  *
387  *    +---------------------------+
388  *    | xfs_dir2_leaf_hdr_t       |
389  *    +---------------------------+
390  *    | xfs_dir2_leaf_entry_t     |
391  *    | xfs_dir2_leaf_entry_t     |
392  *    | xfs_dir2_leaf_entry_t     |
393  *    | xfs_dir2_leaf_entry_t     |
394  *    | ...                       |
395  *    +---------------------------+
396  *    | xfs_dir2_data_off_t       |
397  *    | xfs_dir2_data_off_t       |
398  *    | xfs_dir2_data_off_t       |
399  *    | ...                       |
400  *    +---------------------------+
401  *    | xfs_dir2_leaf_tail_t      |
402  *    +---------------------------+
403  *
404  * The xfs_dir2_data_off_t members (bests) and tail are at the end of the block
405  * for single-leaf (magic = XFS_DIR2_LEAF1_MAGIC) blocks only, but not present
406  * for directories with separate leaf nodes and free space blocks
407  * (magic = XFS_DIR2_LEAFN_MAGIC).
408  *
409  * As all the entries are variable size structures the accessors below should
410  * be used to iterate over them.
411  */
412 
413 /*
414  * Offset of the leaf/node space.  First block in this space
415  * is the btree root.
416  */
417 #define	XFS_DIR2_LEAF_SPACE	1
418 #define	XFS_DIR2_LEAF_OFFSET	(XFS_DIR2_LEAF_SPACE * XFS_DIR2_SPACE_SIZE)
419 
420 /*
421  * Leaf block header.
422  */
423 typedef struct xfs_dir2_leaf_hdr {
424 	xfs_da_blkinfo_t	info;		/* header for da routines */
425 	__be16			count;		/* count of entries */
426 	__be16			stale;		/* count of stale entries */
427 } xfs_dir2_leaf_hdr_t;
428 
429 struct xfs_dir3_leaf_hdr {
430 	struct xfs_da3_blkinfo	info;		/* header for da routines */
431 	__be16			count;		/* count of entries */
432 	__be16			stale;		/* count of stale entries */
433 	__be32			pad;		/* 64 bit alignment */
434 };
435 
436 /*
437  * Leaf block entry.
438  */
439 typedef struct xfs_dir2_leaf_entry {
440 	__be32			hashval;	/* hash value of name */
441 	__be32			address;	/* address of data entry */
442 } xfs_dir2_leaf_entry_t;
443 
444 /*
445  * Leaf block tail.
446  */
447 typedef struct xfs_dir2_leaf_tail {
448 	__be32			bestcount;
449 } xfs_dir2_leaf_tail_t;
450 
451 /*
452  * Leaf block.
453  */
454 typedef struct xfs_dir2_leaf {
455 	xfs_dir2_leaf_hdr_t	hdr;			/* leaf header */
456 	xfs_dir2_leaf_entry_t	__ents[];		/* entries */
457 } xfs_dir2_leaf_t;
458 
459 struct xfs_dir3_leaf {
460 	struct xfs_dir3_leaf_hdr	hdr;		/* leaf header */
461 	struct xfs_dir2_leaf_entry	__ents[];	/* entries */
462 };
463 
464 #define XFS_DIR3_LEAF_CRC_OFF  offsetof(struct xfs_dir3_leaf_hdr, info.crc)
465 
466 /*
467  * Get address of the bests array in the single-leaf block.
468  */
469 static inline __be16 *
470 xfs_dir2_leaf_bests_p(struct xfs_dir2_leaf_tail *ltp)
471 {
472 	return (__be16 *)ltp - be32_to_cpu(ltp->bestcount);
473 }
474 
475 /*
476  * Free space block definitions for the node format.
477  */
478 
479 /*
480  * Offset of the freespace index.
481  */
482 #define	XFS_DIR2_FREE_SPACE	2
483 #define	XFS_DIR2_FREE_OFFSET	(XFS_DIR2_FREE_SPACE * XFS_DIR2_SPACE_SIZE)
484 
485 typedef	struct xfs_dir2_free_hdr {
486 	__be32			magic;		/* XFS_DIR2_FREE_MAGIC */
487 	__be32			firstdb;	/* db of first entry */
488 	__be32			nvalid;		/* count of valid entries */
489 	__be32			nused;		/* count of used entries */
490 } xfs_dir2_free_hdr_t;
491 
492 typedef struct xfs_dir2_free {
493 	xfs_dir2_free_hdr_t	hdr;		/* block header */
494 	__be16			bests[];	/* best free counts */
495 						/* unused entries are -1 */
496 } xfs_dir2_free_t;
497 
498 struct xfs_dir3_free_hdr {
499 	struct xfs_dir3_blk_hdr	hdr;
500 	__be32			firstdb;	/* db of first entry */
501 	__be32			nvalid;		/* count of valid entries */
502 	__be32			nused;		/* count of used entries */
503 	__be32			pad;		/* 64 bit alignment */
504 };
505 
506 struct xfs_dir3_free {
507 	struct xfs_dir3_free_hdr hdr;
508 	__be16			bests[];	/* best free counts */
509 						/* unused entries are -1 */
510 };
511 
512 #define XFS_DIR3_FREE_CRC_OFF  offsetof(struct xfs_dir3_free, hdr.hdr.crc)
513 
514 /*
515  * Single block format.
516  *
517  * The single block format looks like the following drawing on disk:
518  *
519  *    +-------------------------------------------------+
520  *    | xfs_dir2_data_hdr_t                             |
521  *    +-------------------------------------------------+
522  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
523  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
524  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t :
525  *    | ...                                             |
526  *    +-------------------------------------------------+
527  *    | unused space                                    |
528  *    +-------------------------------------------------+
529  *    | ...                                             |
530  *    | xfs_dir2_leaf_entry_t                           |
531  *    | xfs_dir2_leaf_entry_t                           |
532  *    +-------------------------------------------------+
533  *    | xfs_dir2_block_tail_t                           |
534  *    +-------------------------------------------------+
535  *
536  * As all the entries are variable size structures the accessors below should
537  * be used to iterate over them.
538  */
539 
540 typedef struct xfs_dir2_block_tail {
541 	__be32		count;			/* count of leaf entries */
542 	__be32		stale;			/* count of stale lf entries */
543 } xfs_dir2_block_tail_t;
544 
545 /*
546  * Pointer to the leaf entries embedded in a data block (1-block format)
547  */
548 static inline struct xfs_dir2_leaf_entry *
549 xfs_dir2_block_leaf_p(struct xfs_dir2_block_tail *btp)
550 {
551 	return ((struct xfs_dir2_leaf_entry *)btp) - be32_to_cpu(btp->count);
552 }
553 
554 
555 /*
556  * Attribute storage layout
557  *
558  * Attribute lists are structured around Btrees where all the data
559  * elements are in the leaf nodes.  Attribute names are hashed into an int,
560  * then that int is used as the index into the Btree.  Since the hashval
561  * of an attribute name may not be unique, we may have duplicate keys.  The
562  * internal links in the Btree are logical block offsets into the file.
563  *
564  * Struct leaf_entry's are packed from the top.  Name/values grow from the
565  * bottom but are not packed.  The freemap contains run-length-encoded entries
566  * for the free bytes after the leaf_entry's, but only the N largest such,
567  * smaller runs are dropped.  When the freemap doesn't show enough space
568  * for an allocation, we compact the name/value area and try again.  If we
569  * still don't have enough space, then we have to split the block.  The
570  * name/value structs (both local and remote versions) must be 32bit aligned.
571  *
572  * Since we have duplicate hash keys, for each key that matches, compare
573  * the actual name string.  The root and intermediate node search always
574  * takes the first-in-the-block key match found, so we should only have
575  * to work "forw"ard.  If none matches, continue with the "forw"ard leaf
576  * nodes until the hash key changes or the attribute name is found.
577  *
578  * We store the fact that an attribute is a ROOT/USER/SECURE attribute in
579  * the leaf_entry.  The namespaces are independent only because we also look
580  * at the namespace bit when we are looking for a matching attribute name.
581  *
582  * We also store an "incomplete" bit in the leaf_entry.  It shows that an
583  * attribute is in the middle of being created and should not be shown to
584  * the user if we crash during the time that the bit is set.  We clear the
585  * bit when we have finished setting up the attribute.  We do this because
586  * we cannot create some large attributes inside a single transaction, and we
587  * need some indication that we weren't finished if we crash in the middle.
588  */
589 #define XFS_ATTR_LEAF_MAPSIZE	3	/* how many freespace slots */
590 
591 /*
592  * Attribute storage when stored inside the inode.
593  *
594  * Small attribute lists are packed as tightly as possible so as to fit into the
595  * literal area of the inode.
596  *
597  * These "shortform" attribute forks consist of a single xfs_attr_sf_hdr header
598  * followed by zero or more xfs_attr_sf_entry structures.
599  */
600 struct xfs_attr_sf_hdr {	/* constant-structure header block */
601 	__be16	totsize;	/* total bytes in shortform list */
602 	__u8	count;		/* count of active entries */
603 	__u8	padding;
604 };
605 
606 struct xfs_attr_sf_entry {
607 	__u8	namelen;	/* actual length of name (no NULL) */
608 	__u8	valuelen;	/* actual length of value (no NULL) */
609 	__u8	flags;		/* flags bits (XFS_ATTR_*) */
610 	__u8	nameval[];	/* name & value bytes concatenated */
611 };
612 
613 typedef struct xfs_attr_leaf_map {	/* RLE map of free bytes */
614 	__be16	base;			  /* base of free region */
615 	__be16	size;			  /* length of free region */
616 } xfs_attr_leaf_map_t;
617 
618 typedef struct xfs_attr_leaf_hdr {	/* constant-structure header block */
619 	xfs_da_blkinfo_t info;		/* block type, links, etc. */
620 	__be16	count;			/* count of active leaf_entry's */
621 	__be16	usedbytes;		/* num bytes of names/values stored */
622 	__be16	firstused;		/* first used byte in name area */
623 	__u8	holes;			/* != 0 if blk needs compaction */
624 	__u8	pad1;
625 	xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
626 					/* N largest free regions */
627 } xfs_attr_leaf_hdr_t;
628 
629 typedef struct xfs_attr_leaf_entry {	/* sorted on key, not name */
630 	__be32	hashval;		/* hash value of name */
631 	__be16	nameidx;		/* index into buffer of name/value */
632 	__u8	flags;			/* LOCAL/ROOT/SECURE/INCOMPLETE flag */
633 	__u8	pad2;			/* unused pad byte */
634 } xfs_attr_leaf_entry_t;
635 
636 typedef struct xfs_attr_leaf_name_local {
637 	__be16	valuelen;		/* number of bytes in value */
638 	__u8	namelen;		/* length of name bytes */
639 	/*
640 	 * In Linux 6.5 this flex array was converted from nameval[1] to
641 	 * nameval[].  Be very careful here about extra padding at the end;
642 	 * see xfs_attr_leaf_entsize_local() for details.
643 	 */
644 	__u8	nameval[];		/* name/value bytes */
645 } xfs_attr_leaf_name_local_t;
646 
647 typedef struct xfs_attr_leaf_name_remote {
648 	__be32	valueblk;		/* block number of value bytes */
649 	__be32	valuelen;		/* number of bytes in value */
650 	__u8	namelen;		/* length of name bytes */
651 	/*
652 	 * In Linux 6.5 this flex array was converted from name[1] to name[].
653 	 * Be very careful here about extra padding at the end; see
654 	 * xfs_attr_leaf_entsize_remote() for details.
655 	 */
656 	__u8	name[];			/* name bytes */
657 } xfs_attr_leaf_name_remote_t;
658 
659 typedef struct xfs_attr_leafblock {
660 	xfs_attr_leaf_hdr_t	hdr;	/* constant-structure header block */
661 	xfs_attr_leaf_entry_t	entries[];	/* sorted on key, not name */
662 	/*
663 	 * The rest of the block contains the following structures after the
664 	 * leaf entries, growing from the bottom up. The variables are never
665 	 * referenced and definining them can actually make gcc optimize away
666 	 * accesses to the 'entries' array above index 0 so don't do that.
667 	 *
668 	 * xfs_attr_leaf_name_local_t namelist;
669 	 * xfs_attr_leaf_name_remote_t valuelist;
670 	 */
671 } xfs_attr_leafblock_t;
672 
673 /*
674  * CRC enabled leaf structures. Called "version 3" structures to match the
675  * version number of the directory and dablk structures for this feature, and
676  * attr2 is already taken by the variable inode attribute fork size feature.
677  */
678 struct xfs_attr3_leaf_hdr {
679 	struct xfs_da3_blkinfo	info;
680 	__be16			count;
681 	__be16			usedbytes;
682 	__be16			firstused;
683 	__u8			holes;
684 	__u8			pad1;
685 	struct xfs_attr_leaf_map freemap[XFS_ATTR_LEAF_MAPSIZE];
686 	__be32			pad2;		/* 64 bit alignment */
687 };
688 
689 #define XFS_ATTR3_LEAF_CRC_OFF	(offsetof(struct xfs_attr3_leaf_hdr, info.crc))
690 
691 struct xfs_attr3_leafblock {
692 	struct xfs_attr3_leaf_hdr	hdr;
693 	struct xfs_attr_leaf_entry	entries[];
694 
695 	/*
696 	 * The rest of the block contains the following structures after the
697 	 * leaf entries, growing from the bottom up. The variables are never
698 	 * referenced, the locations accessed purely from helper functions.
699 	 *
700 	 * struct xfs_attr_leaf_name_local
701 	 * struct xfs_attr_leaf_name_remote
702 	 */
703 };
704 
705 /*
706  * Special value to represent fs block size in the leaf header firstused field.
707  * Only used when block size overflows the 2-bytes available on disk.
708  */
709 #define XFS_ATTR3_LEAF_NULLOFF	0
710 
711 /*
712  * Flags used in the leaf_entry[i].flags field.
713  */
714 #define	XFS_ATTR_LOCAL_BIT	0	/* attr is stored locally */
715 #define	XFS_ATTR_ROOT_BIT	1	/* limit access to trusted attrs */
716 #define	XFS_ATTR_SECURE_BIT	2	/* limit access to secure attrs */
717 #define	XFS_ATTR_INCOMPLETE_BIT	7	/* attr in middle of create/delete */
718 #define XFS_ATTR_LOCAL		(1u << XFS_ATTR_LOCAL_BIT)
719 #define XFS_ATTR_ROOT		(1u << XFS_ATTR_ROOT_BIT)
720 #define XFS_ATTR_SECURE		(1u << XFS_ATTR_SECURE_BIT)
721 #define XFS_ATTR_INCOMPLETE	(1u << XFS_ATTR_INCOMPLETE_BIT)
722 #define XFS_ATTR_NSP_ONDISK_MASK	(XFS_ATTR_ROOT | XFS_ATTR_SECURE)
723 
724 /*
725  * Alignment for namelist and valuelist entries (since they are mixed
726  * there can be only one alignment value)
727  */
728 #define	XFS_ATTR_LEAF_NAME_ALIGN	((uint)sizeof(xfs_dablk_t))
729 
730 static inline int
731 xfs_attr3_leaf_hdr_size(struct xfs_attr_leafblock *leafp)
732 {
733 	if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
734 		return sizeof(struct xfs_attr3_leaf_hdr);
735 	return sizeof(struct xfs_attr_leaf_hdr);
736 }
737 
738 static inline struct xfs_attr_leaf_entry *
739 xfs_attr3_leaf_entryp(xfs_attr_leafblock_t *leafp)
740 {
741 	if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
742 		return &((struct xfs_attr3_leafblock *)leafp)->entries[0];
743 	return &leafp->entries[0];
744 }
745 
746 /*
747  * Cast typed pointers for "local" and "remote" name/value structs.
748  */
749 static inline char *
750 xfs_attr3_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
751 {
752 	struct xfs_attr_leaf_entry *entries = xfs_attr3_leaf_entryp(leafp);
753 
754 	return &((char *)leafp)[be16_to_cpu(entries[idx].nameidx)];
755 }
756 
757 static inline xfs_attr_leaf_name_remote_t *
758 xfs_attr3_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
759 {
760 	return (xfs_attr_leaf_name_remote_t *)xfs_attr3_leaf_name(leafp, idx);
761 }
762 
763 static inline xfs_attr_leaf_name_local_t *
764 xfs_attr3_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
765 {
766 	return (xfs_attr_leaf_name_local_t *)xfs_attr3_leaf_name(leafp, idx);
767 }
768 
769 /*
770  * Calculate total bytes used (including trailing pad for alignment) for
771  * a "local" name/value structure, a "remote" name/value structure, and
772  * a pointer which might be either.
773  */
774 static inline int xfs_attr_leaf_entsize_remote(int nlen)
775 {
776 	/*
777 	 * Prior to Linux 6.5, struct xfs_attr_leaf_name_remote ended with
778 	 * name[1], which was used as a flexarray.  The layout of this struct
779 	 * is 9 bytes of fixed-length fields followed by a __u8 flex array at
780 	 * offset 9.
781 	 *
782 	 * On most architectures, struct xfs_attr_leaf_name_remote had two
783 	 * bytes of implicit padding at the end of the struct to make the
784 	 * struct length 12.  After converting name[1] to name[], there are
785 	 * three implicit padding bytes and the struct size remains 12.
786 	 * However, there are compiler configurations that do not add implicit
787 	 * padding at all (m68k) and have been broken for years.
788 	 *
789 	 * This entsize computation historically added (the xattr name length)
790 	 * to (the padded struct length - 1) and rounded that sum up to the
791 	 * nearest multiple of 4 (NAME_ALIGN).  IOWs, round_up(11 + nlen, 4).
792 	 * This is encoded in the ondisk format, so we cannot change this.
793 	 *
794 	 * Compute the entsize from offsetof of the flexarray and manually
795 	 * adding bytes for the implicit padding.
796 	 */
797 	const size_t remotesize =
798 			offsetof(struct xfs_attr_leaf_name_remote, name) + 2;
799 
800 	return round_up(remotesize + nlen, XFS_ATTR_LEAF_NAME_ALIGN);
801 }
802 
803 static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
804 {
805 	/*
806 	 * Prior to Linux 6.5, struct xfs_attr_leaf_name_local ended with
807 	 * nameval[1], which was used as a flexarray.  The layout of this
808 	 * struct is 3 bytes of fixed-length fields followed by a __u8 flex
809 	 * array at offset 3.
810 	 *
811 	 * struct xfs_attr_leaf_name_local had zero bytes of implicit padding
812 	 * at the end of the struct to make the struct length 4.  On most
813 	 * architectures, after converting nameval[1] to nameval[], there is
814 	 * one implicit padding byte and the struct size remains 4.  However,
815 	 * there are compiler configurations that do not add implicit padding
816 	 * at all (m68k) and would break.
817 	 *
818 	 * This entsize computation historically added (the xattr name and
819 	 * value length) to (the padded struct length - 1) and rounded that sum
820 	 * up to the nearest multiple of 4 (NAME_ALIGN).  IOWs, the formula is
821 	 * round_up(3 + nlen + vlen, 4).  This is encoded in the ondisk format,
822 	 * so we cannot change this.
823 	 *
824 	 * Compute the entsize from offsetof of the flexarray and manually
825 	 * adding bytes for the implicit padding.
826 	 */
827 	const size_t localsize =
828 			offsetof(struct xfs_attr_leaf_name_local, nameval);
829 
830 	return round_up(localsize + nlen + vlen, XFS_ATTR_LEAF_NAME_ALIGN);
831 }
832 
833 static inline int xfs_attr_leaf_entsize_local_max(int bsize)
834 {
835 	return (((bsize) >> 1) + ((bsize) >> 2));
836 }
837 
838 
839 
840 /*
841  * Remote attribute block format definition
842  *
843  * There is one of these headers per filesystem block in a remote attribute.
844  * This is done to ensure there is a 1:1 mapping between the attribute value
845  * length and the number of blocks needed to store the attribute. This makes the
846  * verification of a buffer a little more complex, but greatly simplifies the
847  * allocation, reading and writing of these attributes as we don't have to guess
848  * the number of blocks needed to store the attribute data.
849  */
850 #define XFS_ATTR3_RMT_MAGIC	0x5841524d	/* XARM */
851 
852 struct xfs_attr3_rmt_hdr {
853 	__be32	rm_magic;
854 	__be32	rm_offset;
855 	__be32	rm_bytes;
856 	__be32	rm_crc;
857 	uuid_t	rm_uuid;
858 	__be64	rm_owner;
859 	__be64	rm_blkno;
860 	__be64	rm_lsn;
861 };
862 
863 #define XFS_ATTR3_RMT_CRC_OFF	offsetof(struct xfs_attr3_rmt_hdr, rm_crc)
864 
865 #define XFS_ATTR3_RMT_BUF_SPACE(mp, bufsize)	\
866 	((bufsize) - (xfs_has_crc((mp)) ? \
867 			sizeof(struct xfs_attr3_rmt_hdr) : 0))
868 
869 /* Number of bytes in a directory block. */
870 static inline unsigned int xfs_dir2_dirblock_bytes(struct xfs_sb *sbp)
871 {
872 	return 1 << (sbp->sb_blocklog + sbp->sb_dirblklog);
873 }
874 
875 xfs_failaddr_t xfs_da3_blkinfo_verify(struct xfs_buf *bp,
876 				      struct xfs_da3_blkinfo *hdr3);
877 
878 #endif /* __XFS_DA_FORMAT_H__ */
879