1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
11 struct xfs_attr_list_context;
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.
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.
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.
29 #define ATTR_MAX_VALUELEN (64*1024) /* max length of a value */
32 * Kernel-internal version of the attrlist cursor.
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 */
44 /*========================================================================
45 * Structure used to pass context around among the routines.
46 *========================================================================*/
49 /* void; state communicated via *context */
50 typedef void (*put_listent_func_t)(struct xfs_attr_list_context *, int,
51 unsigned char *, int, int);
53 struct xfs_attr_list_context {
55 struct xfs_inode *dp; /* inode */
56 struct xfs_attrlist_cursor_kern cursor; /* position in list */
57 void *buffer; /* output buffer */
60 * Abort attribute list iteration if non-zero. Can be used to pass
61 * error values to the xfs_attr_list caller.
64 bool allow_incomplete;
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 */
78 * ========================================================================
79 * Structure used to pass context around among the delayed routines.
80 * ========================================================================
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.
92 * xfs_attr_remove_iter()
95 * have attr to remove? ──n──> done
100 * are we short form? ──y──> xfs_attr_shortform_remove ──> done
105 * are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
110 * ┌── need to setup state?
115 * │ find attr and get state
116 * │ attr has remote blks? ──n─┐
118 * │ │ find and invalidate
119 * │ y the remote blocks.
120 * │ │ mark attr incomplete
121 * │ ├────────────────┘
125 * Have remote blks to remove? ───y─────┐
126 * │ ^ remove the blks
129 * │ XFS_DAS_RMTBLK <─n── done?
131 * │ one less blk to y
139 * ├─────────────────────────┘
144 * xfs_attr_node_remove_cleanup
156 * XFS_DAS_RM_SHRINK │
168 * Below is a state machine diagram for attr set operations.
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.
184 * xfs_attr_set_iter()
187 * ┌─y─ has an attr fork?
205 * │ xfs_attr_try_sf_addname
208 * │ had enough ──y──> done
214 * │ transform to leaf
217 * │ hold the leaf buffer
224 * └─> release leaf buffer
234 * │ xfs_attr_leaf_try_add()
237 * │ had enough ──────────────y─────────────┐
250 * xfs_attr_node_addname_find_attr │
251 * determines if this │
252 * is create or rename │
253 * find space to store attr │
256 * xfs_attr_node_addname │
259 * fits in a node leaf? ────n─────┐ │
261 * │ │ single leaf node? │
266 * update │ grow the leaf split if │
267 * hashvals └── return -EAGAIN needed │
268 * │ retry leaf add │ │
270 * ├────────────────────────────┘ │
274 * ┌─y── or flip flag? │
282 * │ XFS_DAS_FOUND_LBLK <────────────────┘
285 * │ xfs_attr_leaf_addname()
288 * │ ┌──first time through?
293 * │ │ if we have rmt blks
294 * │ │ find space for them
300 * │ ┌─n─ blks to alloc? <──┐
305 * │ │ alloc one blk │
306 * │ │ return -EAGAIN ──┘
307 * │ │ re-enter with one
308 * │ │ less blk to alloc
311 * │ └───> set the rmt
321 * │ flip incomplete │
325 * │ XFS_DAS_FLIP_LFLAG │
337 * │ XFS_DAS_RM_LBLK │ │
346 * │ XFS_DAS_RD_LEAF │
358 * └──────> XFS_DAS_FOUND_NBLK
370 * │ ┌─>XFS_DAS_ALLOC_NODE
376 * │ └──y── need to alloc
382 * │ set the rmt value
386 * └────────> a rename? ──n─┐
395 * XFS_DAS_FLIP_NFLAG │
405 * ┌────────> old blks │
407 * XFS_DAS_RM_NBLK │ │
410 * └──────y── more to │
428 * Enum values for xfs_attr_intent.xattri_da_state
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.
436 enum xfs_delattr_state {
437 XFS_DAS_UNINIT = 0, /* No state has been set yet */
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.
445 XFS_DAS_SF_ADD, /* Initial sf add state */
446 XFS_DAS_SF_REMOVE, /* Initial sf replace/remove state */
448 XFS_DAS_LEAF_ADD, /* Initial leaf add state */
449 XFS_DAS_LEAF_REMOVE, /* Initial leaf replace/remove state */
451 XFS_DAS_NODE_ADD, /* Initial node add state */
452 XFS_DAS_NODE_REMOVE, /* Initial node replace/remove state */
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 */
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 */
470 XFS_DAS_DONE, /* finished operation */
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" }
495 struct xfs_attri_log_nameval;
498 * Context used for keeping track of delayed attribute operations
500 struct xfs_attr_intent {
502 * used to log this item to an intent containing a list of attrs to
505 struct list_head xattri_list;
507 /* Used in xfs_attr_node_removename to roll through removing blocks */
508 struct xfs_da_state *xattri_da_state;
510 struct xfs_da_args *xattri_da_args;
513 * Shared buffer containing the attr name and value so that the logging
514 * code can share large memory buffers between log items.
516 struct xfs_attri_log_nameval *xattri_nameval;
519 * Used by xfs_attr_set to hold a leaf buffer across a transaction roll
521 struct xfs_buf *xattri_leaf_bp;
523 /* Used to keep track of current state of delayed operation */
524 enum xfs_delattr_state xattri_dela_state;
527 * Attr operation being performed - XFS_ATTRI_OP_FLAGS_*
529 unsigned int xattri_op_flags;
531 /* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
532 xfs_dablk_t xattri_lblkno;
534 struct xfs_bmbt_irec xattri_map;
538 /*========================================================================
539 * Function prototypes for the kernel.
540 *========================================================================*/
543 * Overall external interface routines.
545 int xfs_attr_inactive(struct xfs_inode *dp);
546 int xfs_attr_list_ilocked(struct xfs_attr_list_context *);
547 int xfs_attr_list(struct xfs_attr_list_context *);
548 int xfs_inode_hasattr(struct xfs_inode *ip);
549 bool xfs_attr_is_leaf(struct xfs_inode *ip);
550 int xfs_attr_get_ilocked(struct xfs_da_args *args);
551 int xfs_attr_get(struct xfs_da_args *args);
552 int xfs_attr_set(struct xfs_da_args *args);
553 int xfs_attr_set_iter(struct xfs_attr_intent *attr);
554 int xfs_attr_remove_iter(struct xfs_attr_intent *attr);
555 bool xfs_attr_namecheck(const void *name, size_t length);
556 int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
557 void xfs_init_attr_trans(struct xfs_da_args *args, struct xfs_trans_res *tres,
558 unsigned int *total);
561 * Check to see if the attr should be upgraded from non-existent or shortform to
562 * single-leaf-block attribute list.
565 xfs_attr_is_shortform(
566 struct xfs_inode *ip)
568 return ip->i_afp->if_format == XFS_DINODE_FMT_LOCAL ||
569 (ip->i_afp->if_format == XFS_DINODE_FMT_EXTENTS &&
570 ip->i_afp->if_nextents == 0);
573 static inline enum xfs_delattr_state
574 xfs_attr_init_add_state(struct xfs_da_args *args)
577 * When called from the completion of a attr remove to determine the
578 * next state, the attribute fork may be null. This can occur only occur
579 * on a pure remove, but we grab the next state before we check if a
580 * replace operation is being performed. If we are called from any other
581 * context, i_afp is guaranteed to exist. Hence if the attr fork is
582 * null, we were called from a pure remove operation and so we are done.
584 if (!args->dp->i_afp)
587 args->op_flags |= XFS_DA_OP_ADDNAME;
588 if (xfs_attr_is_shortform(args->dp))
589 return XFS_DAS_SF_ADD;
590 if (xfs_attr_is_leaf(args->dp))
591 return XFS_DAS_LEAF_ADD;
592 return XFS_DAS_NODE_ADD;
595 static inline enum xfs_delattr_state
596 xfs_attr_init_remove_state(struct xfs_da_args *args)
598 args->op_flags |= XFS_DA_OP_REMOVE;
599 if (xfs_attr_is_shortform(args->dp))
600 return XFS_DAS_SF_REMOVE;
601 if (xfs_attr_is_leaf(args->dp))
602 return XFS_DAS_LEAF_REMOVE;
603 return XFS_DAS_NODE_REMOVE;
607 * If we are logging the attributes, then we have to start with removal of the
608 * old attribute so that there is always consistent state that we can recover
609 * from if the system goes down part way through. We always log the new attr
610 * value, so even when we remove the attr first we still have the information in
611 * the log to finish the replace operation atomically.
613 static inline enum xfs_delattr_state
614 xfs_attr_init_replace_state(struct xfs_da_args *args)
616 args->op_flags |= XFS_DA_OP_ADDNAME | XFS_DA_OP_REPLACE;
617 if (args->op_flags & XFS_DA_OP_LOGGED)
618 return xfs_attr_init_remove_state(args);
619 return xfs_attr_init_add_state(args);
622 extern struct kmem_cache *xfs_attr_intent_cache;
623 int __init xfs_attr_intent_init_cache(void);
624 void xfs_attr_intent_destroy_cache(void);
626 #endif /* __XFS_ATTR_H__ */