xref: /linux/include/uapi/linux/btrfs_tree.h (revision 2422547e)
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _BTRFS_CTREE_H_
3 #define _BTRFS_CTREE_H_
4 
5 #include <linux/btrfs.h>
6 #include <linux/types.h>
7 #ifdef __KERNEL__
8 #include <linux/stddef.h>
9 #else
10 #include <stddef.h>
11 #endif
12 
13 /* ASCII for _BHRfS_M, no terminating nul */
14 #define BTRFS_MAGIC 0x4D5F53665248425FULL
15 
16 #define BTRFS_MAX_LEVEL 8
17 
18 /*
19  * We can actually store much bigger names, but lets not confuse the rest of
20  * linux.
21  */
22 #define BTRFS_NAME_LEN 255
23 
24 /*
25  * Theoretical limit is larger, but we keep this down to a sane value. That
26  * should limit greatly the possibility of collisions on inode ref items.
27  */
28 #define BTRFS_LINK_MAX 65535U
29 
30 /*
31  * This header contains the structure definitions and constants used
32  * by file system objects that can be retrieved using
33  * the BTRFS_IOC_SEARCH_TREE ioctl.  That means basically anything that
34  * is needed to describe a leaf node's key or item contents.
35  */
36 
37 /* holds pointers to all of the tree roots */
38 #define BTRFS_ROOT_TREE_OBJECTID 1ULL
39 
40 /* stores information about which extents are in use, and reference counts */
41 #define BTRFS_EXTENT_TREE_OBJECTID 2ULL
42 
43 /*
44  * chunk tree stores translations from logical -> physical block numbering
45  * the super block points to the chunk tree
46  */
47 #define BTRFS_CHUNK_TREE_OBJECTID 3ULL
48 
49 /*
50  * stores information about which areas of a given device are in use.
51  * one per device.  The tree of tree roots points to the device tree
52  */
53 #define BTRFS_DEV_TREE_OBJECTID 4ULL
54 
55 /* one per subvolume, storing files and directories */
56 #define BTRFS_FS_TREE_OBJECTID 5ULL
57 
58 /* directory objectid inside the root tree */
59 #define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
60 
61 /* holds checksums of all the data extents */
62 #define BTRFS_CSUM_TREE_OBJECTID 7ULL
63 
64 /* holds quota configuration and tracking */
65 #define BTRFS_QUOTA_TREE_OBJECTID 8ULL
66 
67 /* for storing items that use the BTRFS_UUID_KEY* types */
68 #define BTRFS_UUID_TREE_OBJECTID 9ULL
69 
70 /* tracks free space in block groups. */
71 #define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
72 
73 /* Holds the block group items for extent tree v2. */
74 #define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL
75 
76 /* Tracks RAID stripes in block groups. */
77 #define BTRFS_RAID_STRIPE_TREE_OBJECTID 12ULL
78 
79 /* device stats in the device tree */
80 #define BTRFS_DEV_STATS_OBJECTID 0ULL
81 
82 /* for storing balance parameters in the root tree */
83 #define BTRFS_BALANCE_OBJECTID -4ULL
84 
85 /* orphan objectid for tracking unlinked/truncated files */
86 #define BTRFS_ORPHAN_OBJECTID -5ULL
87 
88 /* does write ahead logging to speed up fsyncs */
89 #define BTRFS_TREE_LOG_OBJECTID -6ULL
90 #define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL
91 
92 /* for space balancing */
93 #define BTRFS_TREE_RELOC_OBJECTID -8ULL
94 #define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL
95 
96 /*
97  * extent checksums all have this objectid
98  * this allows them to share the logging tree
99  * for fsyncs
100  */
101 #define BTRFS_EXTENT_CSUM_OBJECTID -10ULL
102 
103 /* For storing free space cache */
104 #define BTRFS_FREE_SPACE_OBJECTID -11ULL
105 
106 /*
107  * The inode number assigned to the special inode for storing
108  * free ino cache
109  */
110 #define BTRFS_FREE_INO_OBJECTID -12ULL
111 
112 /* dummy objectid represents multiple objectids */
113 #define BTRFS_MULTIPLE_OBJECTIDS -255ULL
114 
115 /*
116  * All files have objectids in this range.
117  */
118 #define BTRFS_FIRST_FREE_OBJECTID 256ULL
119 #define BTRFS_LAST_FREE_OBJECTID -256ULL
120 #define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL
121 
122 
123 /*
124  * the device items go into the chunk tree.  The key is in the form
125  * [ 1 BTRFS_DEV_ITEM_KEY device_id ]
126  */
127 #define BTRFS_DEV_ITEMS_OBJECTID 1ULL
128 
129 #define BTRFS_BTREE_INODE_OBJECTID 1
130 
131 #define BTRFS_EMPTY_SUBVOL_DIR_OBJECTID 2
132 
133 #define BTRFS_DEV_REPLACE_DEVID 0ULL
134 
135 /*
136  * inode items have the data typically returned from stat and store other
137  * info about object characteristics.  There is one for every file and dir in
138  * the FS
139  */
140 #define BTRFS_INODE_ITEM_KEY		1
141 #define BTRFS_INODE_REF_KEY		12
142 #define BTRFS_INODE_EXTREF_KEY		13
143 #define BTRFS_XATTR_ITEM_KEY		24
144 
145 /*
146  * fs verity items are stored under two different key types on disk.
147  * The descriptor items:
148  * [ inode objectid, BTRFS_VERITY_DESC_ITEM_KEY, offset ]
149  *
150  * At offset 0, we store a btrfs_verity_descriptor_item which tracks the size
151  * of the descriptor item and some extra data for encryption.
152  * Starting at offset 1, these hold the generic fs verity descriptor.  The
153  * latter are opaque to btrfs, we just read and write them as a blob for the
154  * higher level verity code.  The most common descriptor size is 256 bytes.
155  *
156  * The merkle tree items:
157  * [ inode objectid, BTRFS_VERITY_MERKLE_ITEM_KEY, offset ]
158  *
159  * These also start at offset 0, and correspond to the merkle tree bytes.  When
160  * fsverity asks for page 0 of the merkle tree, we pull up one page starting at
161  * offset 0 for this key type.  These are also opaque to btrfs, we're blindly
162  * storing whatever fsverity sends down.
163  */
164 #define BTRFS_VERITY_DESC_ITEM_KEY	36
165 #define BTRFS_VERITY_MERKLE_ITEM_KEY	37
166 
167 #define BTRFS_ORPHAN_ITEM_KEY		48
168 /* reserve 2-15 close to the inode for later flexibility */
169 
170 /*
171  * dir items are the name -> inode pointers in a directory.  There is one
172  * for every name in a directory.  BTRFS_DIR_LOG_ITEM_KEY is no longer used
173  * but it's still defined here for documentation purposes and to help avoid
174  * having its numerical value reused in the future.
175  */
176 #define BTRFS_DIR_LOG_ITEM_KEY  60
177 #define BTRFS_DIR_LOG_INDEX_KEY 72
178 #define BTRFS_DIR_ITEM_KEY	84
179 #define BTRFS_DIR_INDEX_KEY	96
180 /*
181  * extent data is for file data
182  */
183 #define BTRFS_EXTENT_DATA_KEY	108
184 
185 /*
186  * extent csums are stored in a separate tree and hold csums for
187  * an entire extent on disk.
188  */
189 #define BTRFS_EXTENT_CSUM_KEY	128
190 
191 /*
192  * root items point to tree roots.  They are typically in the root
193  * tree used by the super block to find all the other trees
194  */
195 #define BTRFS_ROOT_ITEM_KEY	132
196 
197 /*
198  * root backrefs tie subvols and snapshots to the directory entries that
199  * reference them
200  */
201 #define BTRFS_ROOT_BACKREF_KEY	144
202 
203 /*
204  * root refs make a fast index for listing all of the snapshots and
205  * subvolumes referenced by a given root.  They point directly to the
206  * directory item in the root that references the subvol
207  */
208 #define BTRFS_ROOT_REF_KEY	156
209 
210 /*
211  * extent items are in the extent map tree.  These record which blocks
212  * are used, and how many references there are to each block
213  */
214 #define BTRFS_EXTENT_ITEM_KEY	168
215 
216 /*
217  * The same as the BTRFS_EXTENT_ITEM_KEY, except it's metadata we already know
218  * the length, so we save the level in key->offset instead of the length.
219  */
220 #define BTRFS_METADATA_ITEM_KEY	169
221 
222 /*
223  * Special inline ref key which stores the id of the subvolume which originally
224  * created the extent. This subvolume owns the extent permanently from the
225  * perspective of simple quotas. Needed to know which subvolume to free quota
226  * usage from when the extent is deleted.
227  *
228  * Stored as an inline ref rather to avoid wasting space on a separate item on
229  * top of the existing extent item. However, unlike the other inline refs,
230  * there is one one owner ref per extent rather than one per extent.
231  *
232  * Because of this, it goes at the front of the list of inline refs, and thus
233  * must have a lower type value than any other inline ref type (to satisfy the
234  * disk format rule that inline refs have non-decreasing type).
235  */
236 #define BTRFS_EXTENT_OWNER_REF_KEY	172
237 
238 #define BTRFS_TREE_BLOCK_REF_KEY	176
239 
240 #define BTRFS_EXTENT_DATA_REF_KEY	178
241 
242 /*
243  * Obsolete key. Defintion removed in 6.6, value may be reused in the future.
244  *
245  * #define BTRFS_EXTENT_REF_V0_KEY	180
246  */
247 
248 #define BTRFS_SHARED_BLOCK_REF_KEY	182
249 
250 #define BTRFS_SHARED_DATA_REF_KEY	184
251 
252 /*
253  * block groups give us hints into the extent allocation trees.  Which
254  * blocks are free etc etc
255  */
256 #define BTRFS_BLOCK_GROUP_ITEM_KEY 192
257 
258 /*
259  * Every block group is represented in the free space tree by a free space info
260  * item, which stores some accounting information. It is keyed on
261  * (block_group_start, FREE_SPACE_INFO, block_group_length).
262  */
263 #define BTRFS_FREE_SPACE_INFO_KEY 198
264 
265 /*
266  * A free space extent tracks an extent of space that is free in a block group.
267  * It is keyed on (start, FREE_SPACE_EXTENT, length).
268  */
269 #define BTRFS_FREE_SPACE_EXTENT_KEY 199
270 
271 /*
272  * When a block group becomes very fragmented, we convert it to use bitmaps
273  * instead of extents. A free space bitmap is keyed on
274  * (start, FREE_SPACE_BITMAP, length); the corresponding item is a bitmap with
275  * (length / sectorsize) bits.
276  */
277 #define BTRFS_FREE_SPACE_BITMAP_KEY 200
278 
279 #define BTRFS_DEV_EXTENT_KEY	204
280 #define BTRFS_DEV_ITEM_KEY	216
281 #define BTRFS_CHUNK_ITEM_KEY	228
282 
283 #define BTRFS_RAID_STRIPE_KEY	230
284 
285 /*
286  * Records the overall state of the qgroups.
287  * There's only one instance of this key present,
288  * (0, BTRFS_QGROUP_STATUS_KEY, 0)
289  */
290 #define BTRFS_QGROUP_STATUS_KEY         240
291 /*
292  * Records the currently used space of the qgroup.
293  * One key per qgroup, (0, BTRFS_QGROUP_INFO_KEY, qgroupid).
294  */
295 #define BTRFS_QGROUP_INFO_KEY           242
296 /*
297  * Contains the user configured limits for the qgroup.
298  * One key per qgroup, (0, BTRFS_QGROUP_LIMIT_KEY, qgroupid).
299  */
300 #define BTRFS_QGROUP_LIMIT_KEY          244
301 /*
302  * Records the child-parent relationship of qgroups. For
303  * each relation, 2 keys are present:
304  * (childid, BTRFS_QGROUP_RELATION_KEY, parentid)
305  * (parentid, BTRFS_QGROUP_RELATION_KEY, childid)
306  */
307 #define BTRFS_QGROUP_RELATION_KEY       246
308 
309 /*
310  * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
311  */
312 #define BTRFS_BALANCE_ITEM_KEY	248
313 
314 /*
315  * The key type for tree items that are stored persistently, but do not need to
316  * exist for extended period of time. The items can exist in any tree.
317  *
318  * [subtype, BTRFS_TEMPORARY_ITEM_KEY, data]
319  *
320  * Existing items:
321  *
322  * - balance status item
323  *   (BTRFS_BALANCE_OBJECTID, BTRFS_TEMPORARY_ITEM_KEY, 0)
324  */
325 #define BTRFS_TEMPORARY_ITEM_KEY	248
326 
327 /*
328  * Obsolete name, see BTRFS_PERSISTENT_ITEM_KEY
329  */
330 #define BTRFS_DEV_STATS_KEY		249
331 
332 /*
333  * The key type for tree items that are stored persistently and usually exist
334  * for a long period, eg. filesystem lifetime. The item kinds can be status
335  * information, stats or preference values. The item can exist in any tree.
336  *
337  * [subtype, BTRFS_PERSISTENT_ITEM_KEY, data]
338  *
339  * Existing items:
340  *
341  * - device statistics, store IO stats in the device tree, one key for all
342  *   stats
343  *   (BTRFS_DEV_STATS_OBJECTID, BTRFS_DEV_STATS_KEY, 0)
344  */
345 #define BTRFS_PERSISTENT_ITEM_KEY	249
346 
347 /*
348  * Persistently stores the device replace state in the device tree.
349  * The key is built like this: (0, BTRFS_DEV_REPLACE_KEY, 0).
350  */
351 #define BTRFS_DEV_REPLACE_KEY	250
352 
353 /*
354  * Stores items that allow to quickly map UUIDs to something else.
355  * These items are part of the filesystem UUID tree.
356  * The key is built like this:
357  * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
358  */
359 #if BTRFS_UUID_SIZE != 16
360 #error "UUID items require BTRFS_UUID_SIZE == 16!"
361 #endif
362 #define BTRFS_UUID_KEY_SUBVOL	251	/* for UUIDs assigned to subvols */
363 #define BTRFS_UUID_KEY_RECEIVED_SUBVOL	252	/* for UUIDs assigned to
364 						 * received subvols */
365 
366 /*
367  * string items are for debugging.  They just store a short string of
368  * data in the FS
369  */
370 #define BTRFS_STRING_ITEM_KEY	253
371 
372 /* Maximum metadata block size (nodesize) */
373 #define BTRFS_MAX_METADATA_BLOCKSIZE			65536
374 
375 /* 32 bytes in various csum fields */
376 #define BTRFS_CSUM_SIZE 32
377 
378 /* csum types */
379 enum btrfs_csum_type {
380 	BTRFS_CSUM_TYPE_CRC32	= 0,
381 	BTRFS_CSUM_TYPE_XXHASH	= 1,
382 	BTRFS_CSUM_TYPE_SHA256	= 2,
383 	BTRFS_CSUM_TYPE_BLAKE2	= 3,
384 };
385 
386 /*
387  * flags definitions for directory entry item type
388  *
389  * Used by:
390  * struct btrfs_dir_item.type
391  *
392  * Values 0..7 must match common file type values in fs_types.h.
393  */
394 #define BTRFS_FT_UNKNOWN	0
395 #define BTRFS_FT_REG_FILE	1
396 #define BTRFS_FT_DIR		2
397 #define BTRFS_FT_CHRDEV		3
398 #define BTRFS_FT_BLKDEV		4
399 #define BTRFS_FT_FIFO		5
400 #define BTRFS_FT_SOCK		6
401 #define BTRFS_FT_SYMLINK	7
402 #define BTRFS_FT_XATTR		8
403 #define BTRFS_FT_MAX		9
404 /* Directory contains encrypted data */
405 #define BTRFS_FT_ENCRYPTED	0x80
406 
btrfs_dir_flags_to_ftype(__u8 flags)407 static inline __u8 btrfs_dir_flags_to_ftype(__u8 flags)
408 {
409 	return flags & ~BTRFS_FT_ENCRYPTED;
410 }
411 
412 /*
413  * Inode flags
414  */
415 #define BTRFS_INODE_NODATASUM		(1U << 0)
416 #define BTRFS_INODE_NODATACOW		(1U << 1)
417 #define BTRFS_INODE_READONLY		(1U << 2)
418 #define BTRFS_INODE_NOCOMPRESS		(1U << 3)
419 #define BTRFS_INODE_PREALLOC		(1U << 4)
420 #define BTRFS_INODE_SYNC		(1U << 5)
421 #define BTRFS_INODE_IMMUTABLE		(1U << 6)
422 #define BTRFS_INODE_APPEND		(1U << 7)
423 #define BTRFS_INODE_NODUMP		(1U << 8)
424 #define BTRFS_INODE_NOATIME		(1U << 9)
425 #define BTRFS_INODE_DIRSYNC		(1U << 10)
426 #define BTRFS_INODE_COMPRESS		(1U << 11)
427 
428 #define BTRFS_INODE_ROOT_ITEM_INIT	(1U << 31)
429 
430 #define BTRFS_INODE_FLAG_MASK						\
431 	(BTRFS_INODE_NODATASUM |					\
432 	 BTRFS_INODE_NODATACOW |					\
433 	 BTRFS_INODE_READONLY |						\
434 	 BTRFS_INODE_NOCOMPRESS |					\
435 	 BTRFS_INODE_PREALLOC |						\
436 	 BTRFS_INODE_SYNC |						\
437 	 BTRFS_INODE_IMMUTABLE |					\
438 	 BTRFS_INODE_APPEND |						\
439 	 BTRFS_INODE_NODUMP |						\
440 	 BTRFS_INODE_NOATIME |						\
441 	 BTRFS_INODE_DIRSYNC |						\
442 	 BTRFS_INODE_COMPRESS |						\
443 	 BTRFS_INODE_ROOT_ITEM_INIT)
444 
445 #define BTRFS_INODE_RO_VERITY		(1U << 0)
446 
447 #define BTRFS_INODE_RO_FLAG_MASK	(BTRFS_INODE_RO_VERITY)
448 
449 /*
450  * The key defines the order in the tree, and so it also defines (optimal)
451  * block layout.
452  *
453  * objectid corresponds to the inode number.
454  *
455  * type tells us things about the object, and is a kind of stream selector.
456  * so for a given inode, keys with type of 1 might refer to the inode data,
457  * type of 2 may point to file data in the btree and type == 3 may point to
458  * extents.
459  *
460  * offset is the starting byte offset for this key in the stream.
461  *
462  * btrfs_disk_key is in disk byte order.  struct btrfs_key is always
463  * in cpu native order.  Otherwise they are identical and their sizes
464  * should be the same (ie both packed)
465  */
466 struct btrfs_disk_key {
467 	__le64 objectid;
468 	__u8 type;
469 	__le64 offset;
470 } __attribute__ ((__packed__));
471 
472 struct btrfs_key {
473 	__u64 objectid;
474 	__u8 type;
475 	__u64 offset;
476 } __attribute__ ((__packed__));
477 
478 /*
479  * Every tree block (leaf or node) starts with this header.
480  */
481 struct btrfs_header {
482 	/* These first four must match the super block */
483 	__u8 csum[BTRFS_CSUM_SIZE];
484 	/* FS specific uuid */
485 	__u8 fsid[BTRFS_FSID_SIZE];
486 	/* Which block this node is supposed to live in */
487 	__le64 bytenr;
488 	__le64 flags;
489 
490 	/* Allowed to be different from the super from here on down */
491 	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
492 	__le64 generation;
493 	__le64 owner;
494 	__le32 nritems;
495 	__u8 level;
496 } __attribute__ ((__packed__));
497 
498 /*
499  * This is a very generous portion of the super block, giving us room to
500  * translate 14 chunks with 3 stripes each.
501  */
502 #define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
503 
504 /*
505  * Just in case we somehow lose the roots and are not able to mount, we store
506  * an array of the roots from previous transactions in the super.
507  */
508 #define BTRFS_NUM_BACKUP_ROOTS 4
509 struct btrfs_root_backup {
510 	__le64 tree_root;
511 	__le64 tree_root_gen;
512 
513 	__le64 chunk_root;
514 	__le64 chunk_root_gen;
515 
516 	__le64 extent_root;
517 	__le64 extent_root_gen;
518 
519 	__le64 fs_root;
520 	__le64 fs_root_gen;
521 
522 	__le64 dev_root;
523 	__le64 dev_root_gen;
524 
525 	__le64 csum_root;
526 	__le64 csum_root_gen;
527 
528 	__le64 total_bytes;
529 	__le64 bytes_used;
530 	__le64 num_devices;
531 	/* future */
532 	__le64 unused_64[4];
533 
534 	__u8 tree_root_level;
535 	__u8 chunk_root_level;
536 	__u8 extent_root_level;
537 	__u8 fs_root_level;
538 	__u8 dev_root_level;
539 	__u8 csum_root_level;
540 	/* future and to align */
541 	__u8 unused_8[10];
542 } __attribute__ ((__packed__));
543 
544 /*
545  * A leaf is full of items. offset and size tell us where to find the item in
546  * the leaf (relative to the start of the data area)
547  */
548 struct btrfs_item {
549 	struct btrfs_disk_key key;
550 	__le32 offset;
551 	__le32 size;
552 } __attribute__ ((__packed__));
553 
554 /*
555  * Leaves have an item area and a data area:
556  * [item0, item1....itemN] [free space] [dataN...data1, data0]
557  *
558  * The data is separate from the items to get the keys closer together during
559  * searches.
560  */
561 struct btrfs_leaf {
562 	struct btrfs_header header;
563 	struct btrfs_item items[];
564 } __attribute__ ((__packed__));
565 
566 /*
567  * All non-leaf blocks are nodes, they hold only keys and pointers to other
568  * blocks.
569  */
570 struct btrfs_key_ptr {
571 	struct btrfs_disk_key key;
572 	__le64 blockptr;
573 	__le64 generation;
574 } __attribute__ ((__packed__));
575 
576 struct btrfs_node {
577 	struct btrfs_header header;
578 	struct btrfs_key_ptr ptrs[];
579 } __attribute__ ((__packed__));
580 
581 struct btrfs_dev_item {
582 	/* the internal btrfs device id */
583 	__le64 devid;
584 
585 	/* size of the device */
586 	__le64 total_bytes;
587 
588 	/* bytes used */
589 	__le64 bytes_used;
590 
591 	/* optimal io alignment for this device */
592 	__le32 io_align;
593 
594 	/* optimal io width for this device */
595 	__le32 io_width;
596 
597 	/* minimal io size for this device */
598 	__le32 sector_size;
599 
600 	/* type and info about this device */
601 	__le64 type;
602 
603 	/* expected generation for this device */
604 	__le64 generation;
605 
606 	/*
607 	 * starting byte of this partition on the device,
608 	 * to allow for stripe alignment in the future
609 	 */
610 	__le64 start_offset;
611 
612 	/* grouping information for allocation decisions */
613 	__le32 dev_group;
614 
615 	/* seek speed 0-100 where 100 is fastest */
616 	__u8 seek_speed;
617 
618 	/* bandwidth 0-100 where 100 is fastest */
619 	__u8 bandwidth;
620 
621 	/* btrfs generated uuid for this device */
622 	__u8 uuid[BTRFS_UUID_SIZE];
623 
624 	/* uuid of FS who owns this device */
625 	__u8 fsid[BTRFS_UUID_SIZE];
626 } __attribute__ ((__packed__));
627 
628 struct btrfs_stripe {
629 	__le64 devid;
630 	__le64 offset;
631 	__u8 dev_uuid[BTRFS_UUID_SIZE];
632 } __attribute__ ((__packed__));
633 
634 struct btrfs_chunk {
635 	/* size of this chunk in bytes */
636 	__le64 length;
637 
638 	/* objectid of the root referencing this chunk */
639 	__le64 owner;
640 
641 	__le64 stripe_len;
642 	__le64 type;
643 
644 	/* optimal io alignment for this chunk */
645 	__le32 io_align;
646 
647 	/* optimal io width for this chunk */
648 	__le32 io_width;
649 
650 	/* minimal io size for this chunk */
651 	__le32 sector_size;
652 
653 	/* 2^16 stripes is quite a lot, a second limit is the size of a single
654 	 * item in the btree
655 	 */
656 	__le16 num_stripes;
657 
658 	/* sub stripes only matter for raid10 */
659 	__le16 sub_stripes;
660 	struct btrfs_stripe stripe;
661 	/* additional stripes go here */
662 } __attribute__ ((__packed__));
663 
664 /*
665  * The super block basically lists the main trees of the FS.
666  */
667 struct btrfs_super_block {
668 	/* The first 4 fields must match struct btrfs_header */
669 	__u8 csum[BTRFS_CSUM_SIZE];
670 	/* FS specific UUID, visible to user */
671 	__u8 fsid[BTRFS_FSID_SIZE];
672 	/* This block number */
673 	__le64 bytenr;
674 	__le64 flags;
675 
676 	/* Allowed to be different from the btrfs_header from here own down */
677 	__le64 magic;
678 	__le64 generation;
679 	__le64 root;
680 	__le64 chunk_root;
681 	__le64 log_root;
682 
683 	/*
684 	 * This member has never been utilized since the very beginning, thus
685 	 * it's always 0 regardless of kernel version.  We always use
686 	 * generation + 1 to read log tree root.  So here we mark it deprecated.
687 	 */
688 	__le64 __unused_log_root_transid;
689 	__le64 total_bytes;
690 	__le64 bytes_used;
691 	__le64 root_dir_objectid;
692 	__le64 num_devices;
693 	__le32 sectorsize;
694 	__le32 nodesize;
695 	__le32 __unused_leafsize;
696 	__le32 stripesize;
697 	__le32 sys_chunk_array_size;
698 	__le64 chunk_root_generation;
699 	__le64 compat_flags;
700 	__le64 compat_ro_flags;
701 	__le64 incompat_flags;
702 	__le16 csum_type;
703 	__u8 root_level;
704 	__u8 chunk_root_level;
705 	__u8 log_root_level;
706 	struct btrfs_dev_item dev_item;
707 
708 	char label[BTRFS_LABEL_SIZE];
709 
710 	__le64 cache_generation;
711 	__le64 uuid_tree_generation;
712 
713 	/* The UUID written into btree blocks */
714 	__u8 metadata_uuid[BTRFS_FSID_SIZE];
715 
716 	__u64 nr_global_roots;
717 
718 	/* Future expansion */
719 	__le64 reserved[27];
720 	__u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
721 	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
722 
723 	/* Padded to 4096 bytes */
724 	__u8 padding[565];
725 } __attribute__ ((__packed__));
726 
727 #define BTRFS_FREE_SPACE_EXTENT	1
728 #define BTRFS_FREE_SPACE_BITMAP	2
729 
730 struct btrfs_free_space_entry {
731 	__le64 offset;
732 	__le64 bytes;
733 	__u8 type;
734 } __attribute__ ((__packed__));
735 
736 struct btrfs_free_space_header {
737 	struct btrfs_disk_key location;
738 	__le64 generation;
739 	__le64 num_entries;
740 	__le64 num_bitmaps;
741 } __attribute__ ((__packed__));
742 
743 struct btrfs_raid_stride {
744 	/* The id of device this raid extent lives on. */
745 	__le64 devid;
746 	/* The physical location on disk. */
747 	__le64 physical;
748 } __attribute__ ((__packed__));
749 
750 struct btrfs_stripe_extent {
751 	/* An array of raid strides this stripe is composed of. */
752 	__DECLARE_FLEX_ARRAY(struct btrfs_raid_stride, strides);
753 } __attribute__ ((__packed__));
754 
755 #define BTRFS_HEADER_FLAG_WRITTEN	(1ULL << 0)
756 #define BTRFS_HEADER_FLAG_RELOC		(1ULL << 1)
757 
758 /* Super block flags */
759 /* Errors detected */
760 #define BTRFS_SUPER_FLAG_ERROR		(1ULL << 2)
761 
762 #define BTRFS_SUPER_FLAG_SEEDING	(1ULL << 32)
763 #define BTRFS_SUPER_FLAG_METADUMP	(1ULL << 33)
764 #define BTRFS_SUPER_FLAG_METADUMP_V2	(1ULL << 34)
765 #define BTRFS_SUPER_FLAG_CHANGING_FSID	(1ULL << 35)
766 #define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)
767 
768 /*
769  * Those are temporaray flags utilized by btrfs-progs to do offline conversion.
770  * They are rejected by kernel.
771  * But still keep them all here to avoid conflicts.
772  */
773 #define BTRFS_SUPER_FLAG_CHANGING_BG_TREE	(1ULL << 38)
774 #define BTRFS_SUPER_FLAG_CHANGING_DATA_CSUM	(1ULL << 39)
775 #define BTRFS_SUPER_FLAG_CHANGING_META_CSUM	(1ULL << 40)
776 
777 /*
778  * items in the extent btree are used to record the objectid of the
779  * owner of the block and the number of references
780  */
781 
782 struct btrfs_extent_item {
783 	__le64 refs;
784 	__le64 generation;
785 	__le64 flags;
786 } __attribute__ ((__packed__));
787 
788 struct btrfs_extent_item_v0 {
789 	__le32 refs;
790 } __attribute__ ((__packed__));
791 
792 
793 #define BTRFS_EXTENT_FLAG_DATA		(1ULL << 0)
794 #define BTRFS_EXTENT_FLAG_TREE_BLOCK	(1ULL << 1)
795 
796 /* following flags only apply to tree blocks */
797 
798 /* use full backrefs for extent pointers in the block */
799 #define BTRFS_BLOCK_FLAG_FULL_BACKREF	(1ULL << 8)
800 
801 #define BTRFS_BACKREF_REV_MAX		256
802 #define BTRFS_BACKREF_REV_SHIFT		56
803 #define BTRFS_BACKREF_REV_MASK		(((u64)BTRFS_BACKREF_REV_MAX - 1) << \
804 					 BTRFS_BACKREF_REV_SHIFT)
805 
806 #define BTRFS_OLD_BACKREF_REV		0
807 #define BTRFS_MIXED_BACKREF_REV		1
808 
809 /*
810  * this flag is only used internally by scrub and may be changed at any time
811  * it is only declared here to avoid collisions
812  */
813 #define BTRFS_EXTENT_FLAG_SUPER		(1ULL << 48)
814 
815 struct btrfs_tree_block_info {
816 	struct btrfs_disk_key key;
817 	__u8 level;
818 } __attribute__ ((__packed__));
819 
820 struct btrfs_extent_data_ref {
821 	__le64 root;
822 	__le64 objectid;
823 	__le64 offset;
824 	__le32 count;
825 } __attribute__ ((__packed__));
826 
827 struct btrfs_shared_data_ref {
828 	__le32 count;
829 } __attribute__ ((__packed__));
830 
831 struct btrfs_extent_owner_ref {
832 	__le64 root_id;
833 } __attribute__ ((__packed__));
834 
835 struct btrfs_extent_inline_ref {
836 	__u8 type;
837 	__le64 offset;
838 } __attribute__ ((__packed__));
839 
840 /* dev extents record free space on individual devices.  The owner
841  * field points back to the chunk allocation mapping tree that allocated
842  * the extent.  The chunk tree uuid field is a way to double check the owner
843  */
844 struct btrfs_dev_extent {
845 	__le64 chunk_tree;
846 	__le64 chunk_objectid;
847 	__le64 chunk_offset;
848 	__le64 length;
849 	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
850 } __attribute__ ((__packed__));
851 
852 struct btrfs_inode_ref {
853 	__le64 index;
854 	__le16 name_len;
855 	/* name goes here */
856 } __attribute__ ((__packed__));
857 
858 struct btrfs_inode_extref {
859 	__le64 parent_objectid;
860 	__le64 index;
861 	__le16 name_len;
862 	__u8   name[];
863 	/* name goes here */
864 } __attribute__ ((__packed__));
865 
866 struct btrfs_timespec {
867 	__le64 sec;
868 	__le32 nsec;
869 } __attribute__ ((__packed__));
870 
871 struct btrfs_inode_item {
872 	/* nfs style generation number */
873 	__le64 generation;
874 	/* transid that last touched this inode */
875 	__le64 transid;
876 	__le64 size;
877 	__le64 nbytes;
878 	__le64 block_group;
879 	__le32 nlink;
880 	__le32 uid;
881 	__le32 gid;
882 	__le32 mode;
883 	__le64 rdev;
884 	__le64 flags;
885 
886 	/* modification sequence number for NFS */
887 	__le64 sequence;
888 
889 	/*
890 	 * a little future expansion, for more than this we can
891 	 * just grow the inode item and version it
892 	 */
893 	__le64 reserved[4];
894 	struct btrfs_timespec atime;
895 	struct btrfs_timespec ctime;
896 	struct btrfs_timespec mtime;
897 	struct btrfs_timespec otime;
898 } __attribute__ ((__packed__));
899 
900 struct btrfs_dir_log_item {
901 	__le64 end;
902 } __attribute__ ((__packed__));
903 
904 struct btrfs_dir_item {
905 	struct btrfs_disk_key location;
906 	__le64 transid;
907 	__le16 data_len;
908 	__le16 name_len;
909 	__u8 type;
910 } __attribute__ ((__packed__));
911 
912 #define BTRFS_ROOT_SUBVOL_RDONLY	(1ULL << 0)
913 
914 /*
915  * Internal in-memory flag that a subvolume has been marked for deletion but
916  * still visible as a directory
917  */
918 #define BTRFS_ROOT_SUBVOL_DEAD		(1ULL << 48)
919 
920 struct btrfs_root_item {
921 	struct btrfs_inode_item inode;
922 	__le64 generation;
923 	__le64 root_dirid;
924 	__le64 bytenr;
925 	__le64 byte_limit;
926 	__le64 bytes_used;
927 	__le64 last_snapshot;
928 	__le64 flags;
929 	__le32 refs;
930 	struct btrfs_disk_key drop_progress;
931 	__u8 drop_level;
932 	__u8 level;
933 
934 	/*
935 	 * The following fields appear after subvol_uuids+subvol_times
936 	 * were introduced.
937 	 */
938 
939 	/*
940 	 * This generation number is used to test if the new fields are valid
941 	 * and up to date while reading the root item. Every time the root item
942 	 * is written out, the "generation" field is copied into this field. If
943 	 * anyone ever mounted the fs with an older kernel, we will have
944 	 * mismatching generation values here and thus must invalidate the
945 	 * new fields. See btrfs_update_root and btrfs_find_last_root for
946 	 * details.
947 	 * the offset of generation_v2 is also used as the start for the memset
948 	 * when invalidating the fields.
949 	 */
950 	__le64 generation_v2;
951 	__u8 uuid[BTRFS_UUID_SIZE];
952 	__u8 parent_uuid[BTRFS_UUID_SIZE];
953 	__u8 received_uuid[BTRFS_UUID_SIZE];
954 	__le64 ctransid; /* updated when an inode changes */
955 	__le64 otransid; /* trans when created */
956 	__le64 stransid; /* trans when sent. non-zero for received subvol */
957 	__le64 rtransid; /* trans when received. non-zero for received subvol */
958 	struct btrfs_timespec ctime;
959 	struct btrfs_timespec otime;
960 	struct btrfs_timespec stime;
961 	struct btrfs_timespec rtime;
962 	__le64 reserved[8]; /* for future */
963 } __attribute__ ((__packed__));
964 
965 /*
966  * Btrfs root item used to be smaller than current size.  The old format ends
967  * at where member generation_v2 is.
968  */
btrfs_legacy_root_item_size(void)969 static inline __u32 btrfs_legacy_root_item_size(void)
970 {
971 	return offsetof(struct btrfs_root_item, generation_v2);
972 }
973 
974 /*
975  * this is used for both forward and backward root refs
976  */
977 struct btrfs_root_ref {
978 	__le64 dirid;
979 	__le64 sequence;
980 	__le16 name_len;
981 } __attribute__ ((__packed__));
982 
983 struct btrfs_disk_balance_args {
984 	/*
985 	 * profiles to operate on, single is denoted by
986 	 * BTRFS_AVAIL_ALLOC_BIT_SINGLE
987 	 */
988 	__le64 profiles;
989 
990 	/*
991 	 * usage filter
992 	 * BTRFS_BALANCE_ARGS_USAGE with a single value means '0..N'
993 	 * BTRFS_BALANCE_ARGS_USAGE_RANGE - range syntax, min..max
994 	 */
995 	union {
996 		__le64 usage;
997 		struct {
998 			__le32 usage_min;
999 			__le32 usage_max;
1000 		};
1001 	};
1002 
1003 	/* devid filter */
1004 	__le64 devid;
1005 
1006 	/* devid subset filter [pstart..pend) */
1007 	__le64 pstart;
1008 	__le64 pend;
1009 
1010 	/* btrfs virtual address space subset filter [vstart..vend) */
1011 	__le64 vstart;
1012 	__le64 vend;
1013 
1014 	/*
1015 	 * profile to convert to, single is denoted by
1016 	 * BTRFS_AVAIL_ALLOC_BIT_SINGLE
1017 	 */
1018 	__le64 target;
1019 
1020 	/* BTRFS_BALANCE_ARGS_* */
1021 	__le64 flags;
1022 
1023 	/*
1024 	 * BTRFS_BALANCE_ARGS_LIMIT with value 'limit'
1025 	 * BTRFS_BALANCE_ARGS_LIMIT_RANGE - the extend version can use minimum
1026 	 * and maximum
1027 	 */
1028 	union {
1029 		__le64 limit;
1030 		struct {
1031 			__le32 limit_min;
1032 			__le32 limit_max;
1033 		};
1034 	};
1035 
1036 	/*
1037 	 * Process chunks that cross stripes_min..stripes_max devices,
1038 	 * BTRFS_BALANCE_ARGS_STRIPES_RANGE
1039 	 */
1040 	__le32 stripes_min;
1041 	__le32 stripes_max;
1042 
1043 	__le64 unused[6];
1044 } __attribute__ ((__packed__));
1045 
1046 /*
1047  * store balance parameters to disk so that balance can be properly
1048  * resumed after crash or unmount
1049  */
1050 struct btrfs_balance_item {
1051 	/* BTRFS_BALANCE_* */
1052 	__le64 flags;
1053 
1054 	struct btrfs_disk_balance_args data;
1055 	struct btrfs_disk_balance_args meta;
1056 	struct btrfs_disk_balance_args sys;
1057 
1058 	__le64 unused[4];
1059 } __attribute__ ((__packed__));
1060 
1061 enum {
1062 	BTRFS_FILE_EXTENT_INLINE   = 0,
1063 	BTRFS_FILE_EXTENT_REG      = 1,
1064 	BTRFS_FILE_EXTENT_PREALLOC = 2,
1065 	BTRFS_NR_FILE_EXTENT_TYPES = 3,
1066 };
1067 
1068 struct btrfs_file_extent_item {
1069 	/*
1070 	 * transaction id that created this extent
1071 	 */
1072 	__le64 generation;
1073 	/*
1074 	 * max number of bytes to hold this extent in ram
1075 	 * when we split a compressed extent we can't know how big
1076 	 * each of the resulting pieces will be.  So, this is
1077 	 * an upper limit on the size of the extent in ram instead of
1078 	 * an exact limit.
1079 	 */
1080 	__le64 ram_bytes;
1081 
1082 	/*
1083 	 * 32 bits for the various ways we might encode the data,
1084 	 * including compression and encryption.  If any of these
1085 	 * are set to something a given disk format doesn't understand
1086 	 * it is treated like an incompat flag for reading and writing,
1087 	 * but not for stat.
1088 	 */
1089 	__u8 compression;
1090 	__u8 encryption;
1091 	__le16 other_encoding; /* spare for later use */
1092 
1093 	/* are we inline data or a real extent? */
1094 	__u8 type;
1095 
1096 	/*
1097 	 * disk space consumed by the extent, checksum blocks are included
1098 	 * in these numbers
1099 	 *
1100 	 * At this offset in the structure, the inline extent data start.
1101 	 */
1102 	__le64 disk_bytenr;
1103 	__le64 disk_num_bytes;
1104 	/*
1105 	 * the logical offset in file blocks (no csums)
1106 	 * this extent record is for.  This allows a file extent to point
1107 	 * into the middle of an existing extent on disk, sharing it
1108 	 * between two snapshots (useful if some bytes in the middle of the
1109 	 * extent have changed
1110 	 */
1111 	__le64 offset;
1112 	/*
1113 	 * the logical number of file blocks (no csums included).  This
1114 	 * always reflects the size uncompressed and without encoding.
1115 	 */
1116 	__le64 num_bytes;
1117 
1118 } __attribute__ ((__packed__));
1119 
1120 struct btrfs_csum_item {
1121 	__u8 csum;
1122 } __attribute__ ((__packed__));
1123 
1124 struct btrfs_dev_stats_item {
1125 	/*
1126 	 * grow this item struct at the end for future enhancements and keep
1127 	 * the existing values unchanged
1128 	 */
1129 	__le64 values[BTRFS_DEV_STAT_VALUES_MAX];
1130 } __attribute__ ((__packed__));
1131 
1132 #define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS	0
1133 #define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_AVOID	1
1134 
1135 struct btrfs_dev_replace_item {
1136 	/*
1137 	 * grow this item struct at the end for future enhancements and keep
1138 	 * the existing values unchanged
1139 	 */
1140 	__le64 src_devid;
1141 	__le64 cursor_left;
1142 	__le64 cursor_right;
1143 	__le64 cont_reading_from_srcdev_mode;
1144 
1145 	__le64 replace_state;
1146 	__le64 time_started;
1147 	__le64 time_stopped;
1148 	__le64 num_write_errors;
1149 	__le64 num_uncorrectable_read_errors;
1150 } __attribute__ ((__packed__));
1151 
1152 /* different types of block groups (and chunks) */
1153 #define BTRFS_BLOCK_GROUP_DATA		(1ULL << 0)
1154 #define BTRFS_BLOCK_GROUP_SYSTEM	(1ULL << 1)
1155 #define BTRFS_BLOCK_GROUP_METADATA	(1ULL << 2)
1156 #define BTRFS_BLOCK_GROUP_RAID0		(1ULL << 3)
1157 #define BTRFS_BLOCK_GROUP_RAID1		(1ULL << 4)
1158 #define BTRFS_BLOCK_GROUP_DUP		(1ULL << 5)
1159 #define BTRFS_BLOCK_GROUP_RAID10	(1ULL << 6)
1160 #define BTRFS_BLOCK_GROUP_RAID5         (1ULL << 7)
1161 #define BTRFS_BLOCK_GROUP_RAID6         (1ULL << 8)
1162 #define BTRFS_BLOCK_GROUP_RAID1C3       (1ULL << 9)
1163 #define BTRFS_BLOCK_GROUP_RAID1C4       (1ULL << 10)
1164 #define BTRFS_BLOCK_GROUP_RESERVED	(BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
1165 					 BTRFS_SPACE_INFO_GLOBAL_RSV)
1166 
1167 #define BTRFS_BLOCK_GROUP_TYPE_MASK	(BTRFS_BLOCK_GROUP_DATA |    \
1168 					 BTRFS_BLOCK_GROUP_SYSTEM |  \
1169 					 BTRFS_BLOCK_GROUP_METADATA)
1170 
1171 #define BTRFS_BLOCK_GROUP_PROFILE_MASK	(BTRFS_BLOCK_GROUP_RAID0 |   \
1172 					 BTRFS_BLOCK_GROUP_RAID1 |   \
1173 					 BTRFS_BLOCK_GROUP_RAID1C3 | \
1174 					 BTRFS_BLOCK_GROUP_RAID1C4 | \
1175 					 BTRFS_BLOCK_GROUP_RAID5 |   \
1176 					 BTRFS_BLOCK_GROUP_RAID6 |   \
1177 					 BTRFS_BLOCK_GROUP_DUP |     \
1178 					 BTRFS_BLOCK_GROUP_RAID10)
1179 #define BTRFS_BLOCK_GROUP_RAID56_MASK	(BTRFS_BLOCK_GROUP_RAID5 |   \
1180 					 BTRFS_BLOCK_GROUP_RAID6)
1181 
1182 #define BTRFS_BLOCK_GROUP_RAID1_MASK	(BTRFS_BLOCK_GROUP_RAID1 |   \
1183 					 BTRFS_BLOCK_GROUP_RAID1C3 | \
1184 					 BTRFS_BLOCK_GROUP_RAID1C4)
1185 
1186 /*
1187  * We need a bit for restriper to be able to tell when chunks of type
1188  * SINGLE are available.  This "extended" profile format is used in
1189  * fs_info->avail_*_alloc_bits (in-memory) and balance item fields
1190  * (on-disk).  The corresponding on-disk bit in chunk.type is reserved
1191  * to avoid remappings between two formats in future.
1192  */
1193 #define BTRFS_AVAIL_ALLOC_BIT_SINGLE	(1ULL << 48)
1194 
1195 /*
1196  * A fake block group type that is used to communicate global block reserve
1197  * size to userspace via the SPACE_INFO ioctl.
1198  */
1199 #define BTRFS_SPACE_INFO_GLOBAL_RSV	(1ULL << 49)
1200 
1201 #define BTRFS_EXTENDED_PROFILE_MASK	(BTRFS_BLOCK_GROUP_PROFILE_MASK | \
1202 					 BTRFS_AVAIL_ALLOC_BIT_SINGLE)
1203 
chunk_to_extended(__u64 flags)1204 static inline __u64 chunk_to_extended(__u64 flags)
1205 {
1206 	if ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0)
1207 		flags |= BTRFS_AVAIL_ALLOC_BIT_SINGLE;
1208 
1209 	return flags;
1210 }
extended_to_chunk(__u64 flags)1211 static inline __u64 extended_to_chunk(__u64 flags)
1212 {
1213 	return flags & ~BTRFS_AVAIL_ALLOC_BIT_SINGLE;
1214 }
1215 
1216 struct btrfs_block_group_item {
1217 	__le64 used;
1218 	__le64 chunk_objectid;
1219 	__le64 flags;
1220 } __attribute__ ((__packed__));
1221 
1222 struct btrfs_free_space_info {
1223 	__le32 extent_count;
1224 	__le32 flags;
1225 } __attribute__ ((__packed__));
1226 
1227 #define BTRFS_FREE_SPACE_USING_BITMAPS (1ULL << 0)
1228 
1229 #define BTRFS_QGROUP_LEVEL_SHIFT		48
btrfs_qgroup_level(__u64 qgroupid)1230 static inline __u16 btrfs_qgroup_level(__u64 qgroupid)
1231 {
1232 	return (__u16)(qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT);
1233 }
1234 
1235 /*
1236  * is subvolume quota turned on?
1237  */
1238 #define BTRFS_QGROUP_STATUS_FLAG_ON		(1ULL << 0)
1239 /*
1240  * RESCAN is set during the initialization phase
1241  */
1242 #define BTRFS_QGROUP_STATUS_FLAG_RESCAN		(1ULL << 1)
1243 /*
1244  * Some qgroup entries are known to be out of date,
1245  * either because the configuration has changed in a way that
1246  * makes a rescan necessary, or because the fs has been mounted
1247  * with a non-qgroup-aware version.
1248  * Turning qouta off and on again makes it inconsistent, too.
1249  */
1250 #define BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT	(1ULL << 2)
1251 
1252 /*
1253  * Whether or not this filesystem is using simple quotas.  Not exactly the
1254  * incompat bit, because we support using simple quotas, disabling it, then
1255  * going back to full qgroup quotas.
1256  */
1257 #define BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE	(1ULL << 3)
1258 
1259 #define BTRFS_QGROUP_STATUS_FLAGS_MASK	(BTRFS_QGROUP_STATUS_FLAG_ON |		\
1260 					 BTRFS_QGROUP_STATUS_FLAG_RESCAN |	\
1261 					 BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT | \
1262 					 BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE)
1263 
1264 #define BTRFS_QGROUP_STATUS_VERSION        1
1265 
1266 struct btrfs_qgroup_status_item {
1267 	__le64 version;
1268 	/*
1269 	 * the generation is updated during every commit. As older
1270 	 * versions of btrfs are not aware of qgroups, it will be
1271 	 * possible to detect inconsistencies by checking the
1272 	 * generation on mount time
1273 	 */
1274 	__le64 generation;
1275 
1276 	/* flag definitions see above */
1277 	__le64 flags;
1278 
1279 	/*
1280 	 * only used during scanning to record the progress
1281 	 * of the scan. It contains a logical address
1282 	 */
1283 	__le64 rescan;
1284 
1285 	/*
1286 	 * The generation when quotas were last enabled. Used by simple quotas to
1287 	 * avoid decrementing when freeing an extent that was written before
1288 	 * enable.
1289 	 *
1290 	 * Set only if flags contain BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE.
1291 	 */
1292 	__le64 enable_gen;
1293 } __attribute__ ((__packed__));
1294 
1295 struct btrfs_qgroup_info_item {
1296 	__le64 generation;
1297 	__le64 rfer;
1298 	__le64 rfer_cmpr;
1299 	__le64 excl;
1300 	__le64 excl_cmpr;
1301 } __attribute__ ((__packed__));
1302 
1303 struct btrfs_qgroup_limit_item {
1304 	/*
1305 	 * only updated when any of the other values change
1306 	 */
1307 	__le64 flags;
1308 	__le64 max_rfer;
1309 	__le64 max_excl;
1310 	__le64 rsv_rfer;
1311 	__le64 rsv_excl;
1312 } __attribute__ ((__packed__));
1313 
1314 struct btrfs_verity_descriptor_item {
1315 	/* Size of the verity descriptor in bytes */
1316 	__le64 size;
1317 	/*
1318 	 * When we implement support for fscrypt, we will need to encrypt the
1319 	 * Merkle tree for encrypted verity files. These 128 bits are for the
1320 	 * eventual storage of an fscrypt initialization vector.
1321 	 */
1322 	__le64 reserved[2];
1323 	__u8 encryption;
1324 } __attribute__ ((__packed__));
1325 
1326 #endif /* _BTRFS_CTREE_H_ */
1327