1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
4 * All Rights Reserved.
5 */
6 #ifndef __XFS_ATTR_H__
7 #define __XFS_ATTR_H__
8
9 struct xfs_inode;
10 struct xfs_da_args;
11 struct xfs_attr_list_context;
12
13 /*
14 * Large attribute lists are structured around Btrees where all the data
15 * elements are in the leaf nodes. Attribute names are hashed into an int,
16 * then that int is used as the index into the Btree. Since the hashval
17 * of an attribute name may not be unique, we may have duplicate keys.
18 * The internal links in the Btree are logical block offsets into the file.
19 *
20 * Small attribute lists use a different format and are packed as tightly
21 * as possible so as to fit into the literal area of the inode.
22 */
23
24 /*
25 * The maximum size (into the kernel or returned from the kernel) of an
26 * attribute value or the buffer used for an attr_list() call. Larger
27 * sizes will result in an ERANGE return code.
28 */
29 #define ATTR_MAX_VALUELEN (64*1024) /* max length of a value */
30
31 /*
32 * Kernel-internal version of the attrlist cursor.
33 */
34 struct xfs_attrlist_cursor_kern {
35 __u32 hashval; /* hash value of next entry to add */
36 __u32 blkno; /* block containing entry (suggestion) */
37 __u32 offset; /* offset in list of equal-hashvals */
38 __u16 pad1; /* padding to match user-level */
39 __u8 pad2; /* padding to match user-level */
40 __u8 initted; /* T/F: cursor has been initialized */
41 };
42
43
44 /*========================================================================
45 * Structure used to pass context around among the routines.
46 *========================================================================*/
47
48
49 /* void; state communicated via *context */
50 typedef void (*put_listent_func_t)(struct xfs_attr_list_context *, int,
51 unsigned char *, int, int);
52
53 struct xfs_attr_list_context {
54 struct xfs_trans *tp;
55 struct xfs_inode *dp; /* inode */
56 struct xfs_attrlist_cursor_kern cursor; /* position in list */
57 void *buffer; /* output buffer */
58
59 /*
60 * Abort attribute list iteration if non-zero. Can be used to pass
61 * error values to the xfs_attr_list caller.
62 */
63 int seen_enough;
64 bool allow_incomplete;
65
66 ssize_t count; /* num used entries */
67 int dupcnt; /* count dup hashvals seen */
68 int bufsize; /* total buffer size */
69 int firstu; /* first used byte in buffer */
70 unsigned int attr_filter; /* XFS_ATTR_{ROOT,SECURE} */
71 int resynch; /* T/F: resynch with cursor */
72 put_listent_func_t put_listent; /* list output fmt function */
73 int index; /* index into output buffer */
74 };
75
76
77 /*
78 * ========================================================================
79 * Structure used to pass context around among the delayed routines.
80 * ========================================================================
81 */
82
83 /*
84 * Below is a state machine diagram for attr remove operations. The XFS_DAS_*
85 * states indicate places where the function would return -EAGAIN, and then
86 * immediately resume from after being called by the calling function. States
87 * marked as a "subroutine state" indicate that they belong to a subroutine, and
88 * so the calling function needs to pass them back to that subroutine to allow
89 * it to finish where it left off. But they otherwise do not have a role in the
90 * calling function other than just passing through.
91 *
92 * xfs_attr_remove_iter()
93 * │
94 * v
95 * have attr to remove? ──n──> done
96 * │
97 * y
98 * │
99 * v
100 * are we short form? ──y──> xfs_attr_shortform_remove ──> done
101 * │
102 * n
103 * │
104 * V
105 * are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
106 * │
107 * n
108 * │
109 * V
110 * ┌── need to setup state?
111 * │ │
112 * n y
113 * │ │
114 * │ v
115 * │ find attr and get state
116 * │ attr has remote blks? ──n─┐
117 * │ │ v
118 * │ │ find and invalidate
119 * │ y the remote blocks.
120 * │ │ mark attr incomplete
121 * │ ├────────────────┘
122 * └──────────┤
123 * │
124 * v
125 * Have remote blks to remove? ───y─────┐
126 * │ ^ remove the blks
127 * │ │ │
128 * │ │ v
129 * │ XFS_DAS_RMTBLK <─n── done?
130 * │ re-enter with │
131 * │ one less blk to y
132 * │ remove │
133 * │ V
134 * │ refill the state
135 * n │
136 * │ v
137 * │ XFS_DAS_RM_NAME
138 * │ │
139 * ├─────────────────────────┘
140 * │
141 * v
142 * remove leaf and
143 * update hash with
144 * xfs_attr_node_remove_cleanup
145 * │
146 * v
147 * need to
148 * shrink tree? ─n─┐
149 * │ │
150 * y │
151 * │ │
152 * v │
153 * join leaf │
154 * │ │
155 * v │
156 * XFS_DAS_RM_SHRINK │
157 * │ │
158 * v │
159 * do the shrink │
160 * │ │
161 * v │
162 * free state <──┘
163 * │
164 * v
165 * done
166 *
167 *
168 * Below is a state machine diagram for attr set operations.
169 *
170 * It seems the challenge with understanding this system comes from trying to
171 * absorb the state machine all at once, when really one should only be looking
172 * at it with in the context of a single function. Once a state sensitive
173 * function is called, the idea is that it "takes ownership" of the
174 * state machine. It isn't concerned with the states that may have belonged to
175 * it's calling parent. Only the states relevant to itself or any other
176 * subroutines there in. Once a calling function hands off the state machine to
177 * a subroutine, it needs to respect the simple rule that it doesn't "own" the
178 * state machine anymore, and it's the responsibility of that calling function
179 * to propagate the -EAGAIN back up the call stack. Upon reentry, it is
180 * committed to re-calling that subroutine until it returns something other than
181 * -EAGAIN. Once that subroutine signals completion (by returning anything other
182 * than -EAGAIN), the calling function can resume using the state machine.
183 *
184 * xfs_attr_set_iter()
185 * │
186 * v
187 * ┌─y─ has an attr fork?
188 * │ |
189 * │ n
190 * │ |
191 * │ V
192 * │ add a fork
193 * │ │
194 * └──────────┤
195 * │
196 * V
197 * ┌─── is shortform?
198 * │ │
199 * │ y
200 * │ │
201 * │ V
202 * │ xfs_attr_set_fmt
203 * │ |
204 * │ V
205 * │ xfs_attr_try_sf_addname
206 * │ │
207 * │ V
208 * │ had enough ──y──> done
209 * │ space?
210 * n │
211 * │ n
212 * │ │
213 * │ V
214 * │ transform to leaf
215 * │ │
216 * │ V
217 * │ hold the leaf buffer
218 * │ │
219 * │ V
220 * │ return -EAGAIN
221 * │ Re-enter in
222 * │ leaf form
223 * │
224 * └─> release leaf buffer
225 * if needed
226 * │
227 * V
228 * ┌───n── fork has
229 * │ only 1 blk?
230 * │ │
231 * │ y
232 * │ │
233 * │ v
234 * │ xfs_attr_leaf_try_add()
235 * │ │
236 * │ v
237 * │ had enough ──────────────y─────────────┐
238 * │ space? │
239 * │ │ │
240 * │ n │
241 * │ │ │
242 * │ v │
243 * │ return -EAGAIN │
244 * │ re-enter in │
245 * │ node form │
246 * │ │ │
247 * └──────────┤ │
248 * │ │
249 * V │
250 * xfs_attr_node_addname_find_attr │
251 * determines if this │
252 * is create or rename │
253 * find space to store attr │
254 * │ │
255 * v │
256 * xfs_attr_node_addname │
257 * │ │
258 * v │
259 * fits in a node leaf? ────n─────┐ │
260 * │ ^ v │
261 * │ │ single leaf node? │
262 * │ │ │ │ │
263 * y │ y n │
264 * │ │ │ │ │
265 * v │ v v │
266 * update │ grow the leaf split if │
267 * hashvals └── return -EAGAIN needed │
268 * │ retry leaf add │ │
269 * │ on reentry │ │
270 * ├────────────────────────────┘ │
271 * │ │
272 * v │
273 * need to alloc │
274 * ┌─y── or flip flag? │
275 * │ │ │
276 * │ n │
277 * │ │ │
278 * │ v │
279 * │ done │
280 * │ │
281 * │ │
282 * │ XFS_DAS_FOUND_LBLK <────────────────┘
283 * │ │
284 * │ V
285 * │ xfs_attr_leaf_addname()
286 * │ │
287 * │ v
288 * │ ┌──first time through?
289 * │ │ │
290 * │ │ y
291 * │ │ │
292 * │ n v
293 * │ │ if we have rmt blks
294 * │ │ find space for them
295 * │ │ │
296 * │ └──────────┤
297 * │ │
298 * │ v
299 * │ still have
300 * │ ┌─n─ blks to alloc? <──┐
301 * │ │ │ │
302 * │ │ y │
303 * │ │ │ │
304 * │ │ v │
305 * │ │ alloc one blk │
306 * │ │ return -EAGAIN ──┘
307 * │ │ re-enter with one
308 * │ │ less blk to alloc
309 * │ │
310 * │ │
311 * │ └───> set the rmt
312 * │ value
313 * │ │
314 * │ v
315 * │ was this
316 * │ a rename? ──n─┐
317 * │ │ │
318 * │ y │
319 * │ │ │
320 * │ v │
321 * │ flip incomplete │
322 * │ flag │
323 * │ │ │
324 * │ v │
325 * │ XFS_DAS_FLIP_LFLAG │
326 * │ │ │
327 * │ v │
328 * │ need to remove │
329 * │ old bks? ──n──┤
330 * │ │ │
331 * │ y │
332 * │ │ │
333 * │ V │
334 * │ remove │
335 * │ ┌───> old blks │
336 * │ │ │ │
337 * │ XFS_DAS_RM_LBLK │ │
338 * │ ^ │ │
339 * │ │ v │
340 * │ └──y── more to │
341 * │ remove? │
342 * │ │ │
343 * │ n │
344 * │ │ │
345 * │ v │
346 * │ XFS_DAS_RD_LEAF │
347 * │ │ │
348 * │ v │
349 * │ remove leaf │
350 * │ │ │
351 * │ v │
352 * │ shrink to sf │
353 * │ if needed │
354 * │ │ │
355 * │ v │
356 * │ done <──────┘
357 * │
358 * └──────> XFS_DAS_FOUND_NBLK
359 * │
360 * v
361 * ┌─────n── need to
362 * │ alloc blks?
363 * │ │
364 * │ y
365 * │ │
366 * │ v
367 * │ find space
368 * │ │
369 * │ v
370 * │ ┌─>XFS_DAS_ALLOC_NODE
371 * │ │ │
372 * │ │ v
373 * │ │ alloc blk
374 * │ │ │
375 * │ │ v
376 * │ └──y── need to alloc
377 * │ more blocks?
378 * │ │
379 * │ n
380 * │ │
381 * │ v
382 * │ set the rmt value
383 * │ │
384 * │ v
385 * │ was this
386 * └────────> a rename? ──n─┐
387 * │ │
388 * y │
389 * │ │
390 * v │
391 * flip incomplete │
392 * flag │
393 * │ │
394 * v │
395 * XFS_DAS_FLIP_NFLAG │
396 * │ │
397 * v │
398 * need to │
399 * remove blks? ─n──┤
400 * │ │
401 * y │
402 * │ │
403 * v │
404 * remove │
405 * ┌────────> old blks │
406 * │ │ │
407 * XFS_DAS_RM_NBLK │ │
408 * ^ │ │
409 * │ v │
410 * └──────y── more to │
411 * remove │
412 * │ │
413 * n │
414 * │ │
415 * v │
416 * XFS_DAS_CLR_FLAG │
417 * │ │
418 * v │
419 * clear flags │
420 * │ │
421 * ├──────────┘
422 * │
423 * v
424 * done
425 */
426
427 /*
428 * Enum values for xfs_attr_intent.xattri_da_state
429 *
430 * These values are used by delayed attribute operations to keep track of where
431 * they were before they returned -EAGAIN. A return code of -EAGAIN signals the
432 * calling function to roll the transaction, and then call the subroutine to
433 * finish the operation. The enum is then used by the subroutine to jump back
434 * to where it was and resume executing where it left off.
435 */
436 enum xfs_delattr_state {
437 XFS_DAS_UNINIT = 0, /* No state has been set yet */
438
439 /*
440 * Initial sequence states. The replace setup code relies on the
441 * ADD and REMOVE states for a specific format to be sequential so
442 * that we can transform the initial operation to be performed
443 * according to the xfs_has_larp() state easily.
444 */
445 XFS_DAS_SF_ADD, /* Initial sf add state */
446 XFS_DAS_SF_REMOVE, /* Initial sf replace/remove state */
447
448 XFS_DAS_LEAF_ADD, /* Initial leaf add state */
449 XFS_DAS_LEAF_REMOVE, /* Initial leaf replace/remove state */
450
451 XFS_DAS_NODE_ADD, /* Initial node add state */
452 XFS_DAS_NODE_REMOVE, /* Initial node replace/remove state */
453
454 /* Leaf state set/replace/remove sequence */
455 XFS_DAS_LEAF_SET_RMT, /* set a remote xattr from a leaf */
456 XFS_DAS_LEAF_ALLOC_RMT, /* We are allocating remote blocks */
457 XFS_DAS_LEAF_REPLACE, /* Perform replace ops on a leaf */
458 XFS_DAS_LEAF_REMOVE_OLD, /* Start removing old attr from leaf */
459 XFS_DAS_LEAF_REMOVE_RMT, /* A rename is removing remote blocks */
460 XFS_DAS_LEAF_REMOVE_ATTR, /* Remove the old attr from a leaf */
461
462 /* Node state sequence, must match leaf state above */
463 XFS_DAS_NODE_SET_RMT, /* set a remote xattr from a node */
464 XFS_DAS_NODE_ALLOC_RMT, /* We are allocating remote blocks */
465 XFS_DAS_NODE_REPLACE, /* Perform replace ops on a node */
466 XFS_DAS_NODE_REMOVE_OLD, /* Start removing old attr from node */
467 XFS_DAS_NODE_REMOVE_RMT, /* A rename is removing remote blocks */
468 XFS_DAS_NODE_REMOVE_ATTR, /* Remove the old attr from a node */
469
470 XFS_DAS_DONE, /* finished operation */
471 };
472
473 #define XFS_DAS_STRINGS \
474 { XFS_DAS_UNINIT, "XFS_DAS_UNINIT" }, \
475 { XFS_DAS_SF_ADD, "XFS_DAS_SF_ADD" }, \
476 { XFS_DAS_SF_REMOVE, "XFS_DAS_SF_REMOVE" }, \
477 { XFS_DAS_LEAF_ADD, "XFS_DAS_LEAF_ADD" }, \
478 { XFS_DAS_LEAF_REMOVE, "XFS_DAS_LEAF_REMOVE" }, \
479 { XFS_DAS_NODE_ADD, "XFS_DAS_NODE_ADD" }, \
480 { XFS_DAS_NODE_REMOVE, "XFS_DAS_NODE_REMOVE" }, \
481 { XFS_DAS_LEAF_SET_RMT, "XFS_DAS_LEAF_SET_RMT" }, \
482 { XFS_DAS_LEAF_ALLOC_RMT, "XFS_DAS_LEAF_ALLOC_RMT" }, \
483 { XFS_DAS_LEAF_REPLACE, "XFS_DAS_LEAF_REPLACE" }, \
484 { XFS_DAS_LEAF_REMOVE_OLD, "XFS_DAS_LEAF_REMOVE_OLD" }, \
485 { XFS_DAS_LEAF_REMOVE_RMT, "XFS_DAS_LEAF_REMOVE_RMT" }, \
486 { XFS_DAS_LEAF_REMOVE_ATTR, "XFS_DAS_LEAF_REMOVE_ATTR" }, \
487 { XFS_DAS_NODE_SET_RMT, "XFS_DAS_NODE_SET_RMT" }, \
488 { XFS_DAS_NODE_ALLOC_RMT, "XFS_DAS_NODE_ALLOC_RMT" }, \
489 { XFS_DAS_NODE_REPLACE, "XFS_DAS_NODE_REPLACE" }, \
490 { XFS_DAS_NODE_REMOVE_OLD, "XFS_DAS_NODE_REMOVE_OLD" }, \
491 { XFS_DAS_NODE_REMOVE_RMT, "XFS_DAS_NODE_REMOVE_RMT" }, \
492 { XFS_DAS_NODE_REMOVE_ATTR, "XFS_DAS_NODE_REMOVE_ATTR" }, \
493 { XFS_DAS_DONE, "XFS_DAS_DONE" }
494
495 struct xfs_attri_log_nameval;
496
497 /*
498 * Context used for keeping track of delayed attribute operations
499 */
500 struct xfs_attr_intent {
501 /*
502 * used to log this item to an intent containing a list of attrs to
503 * commit later
504 */
505 struct list_head xattri_list;
506
507 /* Used in xfs_attr_node_removename to roll through removing blocks */
508 struct xfs_da_state *xattri_da_state;
509
510 struct xfs_da_args *xattri_da_args;
511
512 /*
513 * Shared buffer containing the attr name and value so that the logging
514 * code can share large memory buffers between log items.
515 */
516 struct xfs_attri_log_nameval *xattri_nameval;
517
518 /* Used to keep track of current state of delayed operation */
519 enum xfs_delattr_state xattri_dela_state;
520
521 /*
522 * Attr operation being performed - XFS_ATTRI_OP_FLAGS_*
523 */
524 unsigned int xattri_op_flags;
525
526 /* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
527 xfs_dablk_t xattri_lblkno;
528 int xattri_blkcnt;
529 struct xfs_bmbt_irec xattri_map;
530 };
531
532
533 /*========================================================================
534 * Function prototypes for the kernel.
535 *========================================================================*/
536
537 /*
538 * Overall external interface routines.
539 */
540 int xfs_attr_inactive(struct xfs_inode *dp);
541 int xfs_attr_list_ilocked(struct xfs_attr_list_context *);
542 int xfs_attr_list(struct xfs_attr_list_context *);
543 int xfs_inode_hasattr(struct xfs_inode *ip);
544 bool xfs_attr_is_leaf(struct xfs_inode *ip);
545 int xfs_attr_get_ilocked(struct xfs_da_args *args);
546 int xfs_attr_get(struct xfs_da_args *args);
547 int xfs_attr_set(struct xfs_da_args *args);
548 int xfs_attr_set_iter(struct xfs_attr_intent *attr);
549 int xfs_attr_remove_iter(struct xfs_attr_intent *attr);
550 bool xfs_attr_namecheck(const void *name, size_t length);
551 int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
552 void xfs_init_attr_trans(struct xfs_da_args *args, struct xfs_trans_res *tres,
553 unsigned int *total);
554
555 /*
556 * Check to see if the attr should be upgraded from non-existent or shortform to
557 * single-leaf-block attribute list.
558 */
559 static inline bool
xfs_attr_is_shortform(struct xfs_inode * ip)560 xfs_attr_is_shortform(
561 struct xfs_inode *ip)
562 {
563 return ip->i_af.if_format == XFS_DINODE_FMT_LOCAL ||
564 (ip->i_af.if_format == XFS_DINODE_FMT_EXTENTS &&
565 ip->i_af.if_nextents == 0);
566 }
567
568 static inline enum xfs_delattr_state
xfs_attr_init_add_state(struct xfs_da_args * args)569 xfs_attr_init_add_state(struct xfs_da_args *args)
570 {
571 /*
572 * When called from the completion of a attr remove to determine the
573 * next state, the attribute fork may be null. This can occur only occur
574 * on a pure remove, but we grab the next state before we check if a
575 * replace operation is being performed. If we are called from any other
576 * context, i_af is guaranteed to exist. Hence if the attr fork is
577 * null, we were called from a pure remove operation and so we are done.
578 */
579 if (!xfs_inode_has_attr_fork(args->dp))
580 return XFS_DAS_DONE;
581
582 args->op_flags |= XFS_DA_OP_ADDNAME;
583 if (xfs_attr_is_shortform(args->dp))
584 return XFS_DAS_SF_ADD;
585 if (xfs_attr_is_leaf(args->dp))
586 return XFS_DAS_LEAF_ADD;
587 return XFS_DAS_NODE_ADD;
588 }
589
590 static inline enum xfs_delattr_state
xfs_attr_init_remove_state(struct xfs_da_args * args)591 xfs_attr_init_remove_state(struct xfs_da_args *args)
592 {
593 args->op_flags |= XFS_DA_OP_REMOVE;
594 if (xfs_attr_is_shortform(args->dp))
595 return XFS_DAS_SF_REMOVE;
596 if (xfs_attr_is_leaf(args->dp))
597 return XFS_DAS_LEAF_REMOVE;
598 return XFS_DAS_NODE_REMOVE;
599 }
600
601 /*
602 * If we are logging the attributes, then we have to start with removal of the
603 * old attribute so that there is always consistent state that we can recover
604 * from if the system goes down part way through. We always log the new attr
605 * value, so even when we remove the attr first we still have the information in
606 * the log to finish the replace operation atomically.
607 */
608 static inline enum xfs_delattr_state
xfs_attr_init_replace_state(struct xfs_da_args * args)609 xfs_attr_init_replace_state(struct xfs_da_args *args)
610 {
611 args->op_flags |= XFS_DA_OP_ADDNAME | XFS_DA_OP_REPLACE;
612 if (args->op_flags & XFS_DA_OP_LOGGED)
613 return xfs_attr_init_remove_state(args);
614 return xfs_attr_init_add_state(args);
615 }
616
617 extern struct kmem_cache *xfs_attr_intent_cache;
618 int __init xfs_attr_intent_init_cache(void);
619 void xfs_attr_intent_destroy_cache(void);
620
621 #endif /* __XFS_ATTR_H__ */
622