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_delattr_context.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 */
438 XFS_DAS_RMTBLK, /* Removing remote blks */
439 XFS_DAS_RM_NAME, /* Remove attr name */
440 XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
441 XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
442 XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
443 XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
444 XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
445 XFS_DAS_RD_LEAF, /* Read in the new leaf */
446 XFS_DAS_ALLOC_NODE, /* We are allocating node blocks */
447 XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
448 XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
449 XFS_DAS_CLR_FLAG, /* Clear incomplete flag */
453 * Defines for xfs_delattr_context.flags
455 #define XFS_DAC_DEFER_FINISH 0x01 /* finish the transaction */
456 #define XFS_DAC_LEAF_ADDNAME_INIT 0x02 /* xfs_attr_leaf_addname init*/
459 * Context used for keeping track of delayed attribute operations
461 struct xfs_delattr_context {
462 struct xfs_da_args *da_args;
464 /* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
465 struct xfs_bmbt_irec map;
469 /* Used in xfs_attr_node_removename to roll through removing blocks */
470 struct xfs_da_state *da_state;
472 /* Used to keep track of current state of delayed operation */
474 enum xfs_delattr_state dela_state;
477 /*========================================================================
478 * Function prototypes for the kernel.
479 *========================================================================*/
482 * Overall external interface routines.
484 int xfs_attr_inactive(struct xfs_inode *dp);
485 int xfs_attr_list_ilocked(struct xfs_attr_list_context *);
486 int xfs_attr_list(struct xfs_attr_list_context *);
487 int xfs_inode_hasattr(struct xfs_inode *ip);
488 bool xfs_attr_is_leaf(struct xfs_inode *ip);
489 int xfs_attr_get_ilocked(struct xfs_da_args *args);
490 int xfs_attr_get(struct xfs_da_args *args);
491 int xfs_attr_set(struct xfs_da_args *args);
492 int xfs_attr_set_args(struct xfs_da_args *args);
493 int xfs_attr_remove_args(struct xfs_da_args *args);
494 int xfs_attr_remove_iter(struct xfs_delattr_context *dac);
495 bool xfs_attr_namecheck(const void *name, size_t length);
496 void xfs_delattr_context_init(struct xfs_delattr_context *dac,
497 struct xfs_da_args *args);
499 #endif /* __XFS_ATTR_H__ */