2 * From linux/include/uapi/linux/btrfs_tree.h
4 * SPDX-License-Identifier: GPL-2.0+
7 #ifndef __BTRFS_BTRFS_TREE_H__
8 #define __BTRFS_BTRFS_TREE_H__
12 #define BTRFS_VOL_NAME_MAX 255
13 #define BTRFS_NAME_MAX 255
14 #define BTRFS_LABEL_SIZE 256
15 #define BTRFS_FSID_SIZE 16
16 #define BTRFS_UUID_SIZE 16
19 * This header contains the structure definitions and constants used
20 * by file system objects that can be retrieved using
21 * the BTRFS_IOC_SEARCH_TREE ioctl. That means basically anything that
22 * is needed to describe a leaf node's key or item contents.
25 /* holds pointers to all of the tree roots */
26 #define BTRFS_ROOT_TREE_OBJECTID 1ULL
28 /* stores information about which extents are in use, and reference counts */
29 #define BTRFS_EXTENT_TREE_OBJECTID 2ULL
32 * chunk tree stores translations from logical -> physical block numbering
33 * the super block points to the chunk tree
35 #define BTRFS_CHUNK_TREE_OBJECTID 3ULL
38 * stores information about which areas of a given device are in use.
39 * one per device. The tree of tree roots points to the device tree
41 #define BTRFS_DEV_TREE_OBJECTID 4ULL
43 /* one per subvolume, storing files and directories */
44 #define BTRFS_FS_TREE_OBJECTID 5ULL
46 /* directory objectid inside the root tree */
47 #define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
49 /* holds checksums of all the data extents */
50 #define BTRFS_CSUM_TREE_OBJECTID 7ULL
52 /* holds quota configuration and tracking */
53 #define BTRFS_QUOTA_TREE_OBJECTID 8ULL
55 /* for storing items that use the BTRFS_UUID_KEY* types */
56 #define BTRFS_UUID_TREE_OBJECTID 9ULL
58 /* tracks free space in block groups. */
59 #define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
61 /* device stats in the device tree */
62 #define BTRFS_DEV_STATS_OBJECTID 0ULL
64 /* for storing balance parameters in the root tree */
65 #define BTRFS_BALANCE_OBJECTID -4ULL
67 /* orhpan objectid for tracking unlinked/truncated files */
68 #define BTRFS_ORPHAN_OBJECTID -5ULL
70 /* does write ahead logging to speed up fsyncs */
71 #define BTRFS_TREE_LOG_OBJECTID -6ULL
72 #define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL
74 /* for space balancing */
75 #define BTRFS_TREE_RELOC_OBJECTID -8ULL
76 #define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL
79 * extent checksums all have this objectid
80 * this allows them to share the logging tree
83 #define BTRFS_EXTENT_CSUM_OBJECTID -10ULL
85 /* For storing free space cache */
86 #define BTRFS_FREE_SPACE_OBJECTID -11ULL
89 * The inode number assigned to the special inode for storing
92 #define BTRFS_FREE_INO_OBJECTID -12ULL
94 /* dummy objectid represents multiple objectids */
95 #define BTRFS_MULTIPLE_OBJECTIDS -255ULL
98 * All files have objectids in this range.
100 #define BTRFS_FIRST_FREE_OBJECTID 256ULL
101 #define BTRFS_LAST_FREE_OBJECTID -256ULL
102 #define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL
106 * the device items go into the chunk tree. The key is in the form
107 * [ 1 BTRFS_DEV_ITEM_KEY device_id ]
109 #define BTRFS_DEV_ITEMS_OBJECTID 1ULL
111 #define BTRFS_BTREE_INODE_OBJECTID 1
113 #define BTRFS_EMPTY_SUBVOL_DIR_OBJECTID 2
115 #define BTRFS_DEV_REPLACE_DEVID 0ULL
118 * inode items have the data typically returned from stat and store other
119 * info about object characteristics. There is one for every file and dir in
122 #define BTRFS_INODE_ITEM_KEY 1
123 #define BTRFS_INODE_REF_KEY 12
124 #define BTRFS_INODE_EXTREF_KEY 13
125 #define BTRFS_XATTR_ITEM_KEY 24
126 #define BTRFS_ORPHAN_ITEM_KEY 48
127 /* reserve 2-15 close to the inode for later flexibility */
130 * dir items are the name -> inode pointers in a directory. There is one
131 * for every name in a directory.
133 #define BTRFS_DIR_LOG_ITEM_KEY 60
134 #define BTRFS_DIR_LOG_INDEX_KEY 72
135 #define BTRFS_DIR_ITEM_KEY 84
136 #define BTRFS_DIR_INDEX_KEY 96
138 * extent data is for file data
140 #define BTRFS_EXTENT_DATA_KEY 108
143 * extent csums are stored in a separate tree and hold csums for
144 * an entire extent on disk.
146 #define BTRFS_EXTENT_CSUM_KEY 128
149 * root items point to tree roots. They are typically in the root
150 * tree used by the super block to find all the other trees
152 #define BTRFS_ROOT_ITEM_KEY 132
155 * root backrefs tie subvols and snapshots to the directory entries that
158 #define BTRFS_ROOT_BACKREF_KEY 144
161 * root refs make a fast index for listing all of the snapshots and
162 * subvolumes referenced by a given root. They point directly to the
163 * directory item in the root that references the subvol
165 #define BTRFS_ROOT_REF_KEY 156
168 * extent items are in the extent map tree. These record which blocks
169 * are used, and how many references there are to each block
171 #define BTRFS_EXTENT_ITEM_KEY 168
174 * The same as the BTRFS_EXTENT_ITEM_KEY, except it's metadata we already know
175 * the length, so we save the level in key->offset instead of the length.
177 #define BTRFS_METADATA_ITEM_KEY 169
179 #define BTRFS_TREE_BLOCK_REF_KEY 176
181 #define BTRFS_EXTENT_DATA_REF_KEY 178
183 #define BTRFS_EXTENT_REF_V0_KEY 180
185 #define BTRFS_SHARED_BLOCK_REF_KEY 182
187 #define BTRFS_SHARED_DATA_REF_KEY 184
190 * block groups give us hints into the extent allocation trees. Which
191 * blocks are free etc etc
193 #define BTRFS_BLOCK_GROUP_ITEM_KEY 192
196 * Every block group is represented in the free space tree by a free space info
197 * item, which stores some accounting information. It is keyed on
198 * (block_group_start, FREE_SPACE_INFO, block_group_length).
200 #define BTRFS_FREE_SPACE_INFO_KEY 198
203 * A free space extent tracks an extent of space that is free in a block group.
204 * It is keyed on (start, FREE_SPACE_EXTENT, length).
206 #define BTRFS_FREE_SPACE_EXTENT_KEY 199
209 * When a block group becomes very fragmented, we convert it to use bitmaps
210 * instead of extents. A free space bitmap is keyed on
211 * (start, FREE_SPACE_BITMAP, length); the corresponding item is a bitmap with
212 * (length / sectorsize) bits.
214 #define BTRFS_FREE_SPACE_BITMAP_KEY 200
216 #define BTRFS_DEV_EXTENT_KEY 204
217 #define BTRFS_DEV_ITEM_KEY 216
218 #define BTRFS_CHUNK_ITEM_KEY 228
221 * Records the overall state of the qgroups.
222 * There's only one instance of this key present,
223 * (0, BTRFS_QGROUP_STATUS_KEY, 0)
225 #define BTRFS_QGROUP_STATUS_KEY 240
227 * Records the currently used space of the qgroup.
228 * One key per qgroup, (0, BTRFS_QGROUP_INFO_KEY, qgroupid).
230 #define BTRFS_QGROUP_INFO_KEY 242
232 * Contains the user configured limits for the qgroup.
233 * One key per qgroup, (0, BTRFS_QGROUP_LIMIT_KEY, qgroupid).
235 #define BTRFS_QGROUP_LIMIT_KEY 244
237 * Records the child-parent relationship of qgroups. For
238 * each relation, 2 keys are present:
239 * (childid, BTRFS_QGROUP_RELATION_KEY, parentid)
240 * (parentid, BTRFS_QGROUP_RELATION_KEY, childid)
242 #define BTRFS_QGROUP_RELATION_KEY 246
245 * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
247 #define BTRFS_BALANCE_ITEM_KEY 248
250 * The key type for tree items that are stored persistently, but do not need to
251 * exist for extended period of time. The items can exist in any tree.
253 * [subtype, BTRFS_TEMPORARY_ITEM_KEY, data]
257 * - balance status item
258 * (BTRFS_BALANCE_OBJECTID, BTRFS_TEMPORARY_ITEM_KEY, 0)
260 #define BTRFS_TEMPORARY_ITEM_KEY 248
263 * Obsolete name, see BTRFS_PERSISTENT_ITEM_KEY
265 #define BTRFS_DEV_STATS_KEY 249
268 * The key type for tree items that are stored persistently and usually exist
269 * for a long period, eg. filesystem lifetime. The item kinds can be status
270 * information, stats or preference values. The item can exist in any tree.
272 * [subtype, BTRFS_PERSISTENT_ITEM_KEY, data]
276 * - device statistics, store IO stats in the device tree, one key for all
278 * (BTRFS_DEV_STATS_OBJECTID, BTRFS_DEV_STATS_KEY, 0)
280 #define BTRFS_PERSISTENT_ITEM_KEY 249
283 * Persistantly stores the device replace state in the device tree.
284 * The key is built like this: (0, BTRFS_DEV_REPLACE_KEY, 0).
286 #define BTRFS_DEV_REPLACE_KEY 250
289 * Stores items that allow to quickly map UUIDs to something else.
290 * These items are part of the filesystem UUID tree.
291 * The key is built like this:
292 * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
294 #if BTRFS_UUID_SIZE != 16
295 #error "UUID items require BTRFS_UUID_SIZE == 16!"
297 #define BTRFS_UUID_KEY_SUBVOL 251 /* for UUIDs assigned to subvols */
298 #define BTRFS_UUID_KEY_RECEIVED_SUBVOL 252 /* for UUIDs assigned to
299 * received subvols */
302 * string items are for debugging. They just store a short string of
305 #define BTRFS_STRING_ITEM_KEY 253
309 /* 32 bytes in various csum fields */
310 #define BTRFS_CSUM_SIZE 32
313 #define BTRFS_CSUM_TYPE_CRC32 0
316 * flags definitions for directory entry item type
319 * struct btrfs_dir_item.type
321 #define BTRFS_FT_UNKNOWN 0
322 #define BTRFS_FT_REG_FILE 1
323 #define BTRFS_FT_DIR 2
324 #define BTRFS_FT_CHRDEV 3
325 #define BTRFS_FT_BLKDEV 4
326 #define BTRFS_FT_FIFO 5
327 #define BTRFS_FT_SOCK 6
328 #define BTRFS_FT_SYMLINK 7
329 #define BTRFS_FT_XATTR 8
330 #define BTRFS_FT_MAX 9
333 * The key defines the order in the tree, and so it also defines (optimal)
336 * objectid corresponds to the inode number.
338 * type tells us things about the object, and is a kind of stream selector.
339 * so for a given inode, keys with type of 1 might refer to the inode data,
340 * type of 2 may point to file data in the btree and type == 3 may point to
343 * offset is the starting byte offset for this key in the stream.
350 } __attribute__ ((__packed__));
352 struct btrfs_dev_item {
353 /* the internal btrfs device id */
356 /* size of the device */
362 /* optimal io alignment for this device */
365 /* optimal io width for this device */
368 /* minimal io size for this device */
371 /* type and info about this device */
374 /* expected generation for this device */
378 * starting byte of this partition on the device,
379 * to allow for stripe alignment in the future
383 /* grouping information for allocation decisions */
386 /* seek speed 0-100 where 100 is fastest */
389 /* bandwidth 0-100 where 100 is fastest */
392 /* btrfs generated uuid for this device */
393 __u8 uuid[BTRFS_UUID_SIZE];
395 /* uuid of FS who owns this device */
396 __u8 fsid[BTRFS_UUID_SIZE];
397 } __attribute__ ((__packed__));
399 struct btrfs_stripe {
402 __u8 dev_uuid[BTRFS_UUID_SIZE];
403 } __attribute__ ((__packed__));
406 /* size of this chunk in bytes */
409 /* objectid of the root referencing this chunk */
415 /* optimal io alignment for this chunk */
418 /* optimal io width for this chunk */
421 /* minimal io size for this chunk */
424 /* 2^16 stripes is quite a lot, a second limit is the size of a single
429 /* sub stripes only matter for raid10 */
431 struct btrfs_stripe stripe;
432 /* additional stripes go here */
433 } __attribute__ ((__packed__));
435 #define BTRFS_FREE_SPACE_EXTENT 1
436 #define BTRFS_FREE_SPACE_BITMAP 2
438 struct btrfs_free_space_entry {
442 } __attribute__ ((__packed__));
444 struct btrfs_free_space_header {
445 struct btrfs_key location;
449 } __attribute__ ((__packed__));
451 #define BTRFS_HEADER_FLAG_WRITTEN (1ULL << 0)
452 #define BTRFS_HEADER_FLAG_RELOC (1ULL << 1)
454 /* Super block flags */
455 /* Errors detected */
456 #define BTRFS_SUPER_FLAG_ERROR (1ULL << 2)
458 #define BTRFS_SUPER_FLAG_SEEDING (1ULL << 32)
459 #define BTRFS_SUPER_FLAG_METADUMP (1ULL << 33)
463 * items in the extent btree are used to record the objectid of the
464 * owner of the block and the number of references
467 struct btrfs_extent_item {
471 } __attribute__ ((__packed__));
474 #define BTRFS_EXTENT_FLAG_DATA (1ULL << 0)
475 #define BTRFS_EXTENT_FLAG_TREE_BLOCK (1ULL << 1)
477 /* following flags only apply to tree blocks */
479 /* use full backrefs for extent pointers in the block */
480 #define BTRFS_BLOCK_FLAG_FULL_BACKREF (1ULL << 8)
483 * this flag is only used internally by scrub and may be changed at any time
484 * it is only declared here to avoid collisions
486 #define BTRFS_EXTENT_FLAG_SUPER (1ULL << 48)
488 struct btrfs_tree_block_info {
489 struct btrfs_key key;
491 } __attribute__ ((__packed__));
493 struct btrfs_extent_data_ref {
498 } __attribute__ ((__packed__));
500 struct btrfs_shared_data_ref {
502 } __attribute__ ((__packed__));
504 struct btrfs_extent_inline_ref {
507 } __attribute__ ((__packed__));
509 /* dev extents record free space on individual devices. The owner
510 * field points back to the chunk allocation mapping tree that allocated
511 * the extent. The chunk tree uuid field is a way to double check the owner
513 struct btrfs_dev_extent {
515 __u64 chunk_objectid;
518 __u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
519 } __attribute__ ((__packed__));
521 struct btrfs_inode_ref {
525 } __attribute__ ((__packed__));
527 struct btrfs_inode_extref {
528 __u64 parent_objectid;
533 } __attribute__ ((__packed__));
535 struct btrfs_timespec {
538 } __attribute__ ((__packed__));
540 struct btrfs_inode_item {
541 /* nfs style generation number */
543 /* transid that last touched this inode */
555 /* modification sequence number for NFS */
559 * a little future expansion, for more than this we can
560 * just grow the inode item and version it
563 struct btrfs_timespec atime;
564 struct btrfs_timespec ctime;
565 struct btrfs_timespec mtime;
566 struct btrfs_timespec otime;
567 } __attribute__ ((__packed__));
569 struct btrfs_dir_log_item {
571 } __attribute__ ((__packed__));
573 struct btrfs_dir_item {
574 struct btrfs_key location;
579 } __attribute__ ((__packed__));
581 #define BTRFS_ROOT_SUBVOL_RDONLY (1ULL << 0)
584 * Internal in-memory flag that a subvolume has been marked for deletion but
585 * still visible as a directory
587 #define BTRFS_ROOT_SUBVOL_DEAD (1ULL << 48)
589 struct btrfs_root_item {
590 struct btrfs_inode_item inode;
599 struct btrfs_key drop_progress;
604 * The following fields appear after subvol_uuids+subvol_times
609 * This generation number is used to test if the new fields are valid
610 * and up to date while reading the root item. Every time the root item
611 * is written out, the "generation" field is copied into this field. If
612 * anyone ever mounted the fs with an older kernel, we will have
613 * mismatching generation values here and thus must invalidate the
614 * new fields. See btrfs_update_root and btrfs_find_last_root for
616 * the offset of generation_v2 is also used as the start for the memset
617 * when invalidating the fields.
620 __u8 uuid[BTRFS_UUID_SIZE];
621 __u8 parent_uuid[BTRFS_UUID_SIZE];
622 __u8 received_uuid[BTRFS_UUID_SIZE];
623 __u64 ctransid; /* updated when an inode changes */
624 __u64 otransid; /* trans when created */
625 __u64 stransid; /* trans when sent. non-zero for received subvol */
626 __u64 rtransid; /* trans when received. non-zero for received subvol */
627 struct btrfs_timespec ctime;
628 struct btrfs_timespec otime;
629 struct btrfs_timespec stime;
630 struct btrfs_timespec rtime;
631 __u64 reserved[8]; /* for future */
632 } __attribute__ ((__packed__));
635 * this is used for both forward and backward root refs
637 struct btrfs_root_ref {
641 } __attribute__ ((__packed__));
643 #define BTRFS_FILE_EXTENT_INLINE 0
644 #define BTRFS_FILE_EXTENT_REG 1
645 #define BTRFS_FILE_EXTENT_PREALLOC 2
647 enum btrfs_compression_type {
648 BTRFS_COMPRESS_NONE = 0,
649 BTRFS_COMPRESS_ZLIB = 1,
650 BTRFS_COMPRESS_LZO = 2,
651 BTRFS_COMPRESS_TYPES = 2,
652 BTRFS_COMPRESS_LAST = 3,
655 struct btrfs_file_extent_item {
657 * transaction id that created this extent
661 * max number of bytes to hold this extent in ram
662 * when we split a compressed extent we can't know how big
663 * each of the resulting pieces will be. So, this is
664 * an upper limit on the size of the extent in ram instead of
670 * 32 bits for the various ways we might encode the data,
671 * including compression and encryption. If any of these
672 * are set to something a given disk format doesn't understand
673 * it is treated like an incompat flag for reading and writing,
678 __u16 other_encoding; /* spare for later use */
680 /* are we inline data or a real extent? */
684 * disk space consumed by the extent, checksum blocks are included
687 * At this offset in the structure, the inline extent data start.
690 __u64 disk_num_bytes;
692 * the logical offset in file blocks (no csums)
693 * this extent record is for. This allows a file extent to point
694 * into the middle of an existing extent on disk, sharing it
695 * between two snapshots (useful if some bytes in the middle of the
696 * extent have changed
700 * the logical number of file blocks (no csums included). This
701 * always reflects the size uncompressed and without encoding.
705 } __attribute__ ((__packed__));
707 struct btrfs_csum_item {
709 } __attribute__ ((__packed__));
711 /* different types of block groups (and chunks) */
712 #define BTRFS_BLOCK_GROUP_DATA (1ULL << 0)
713 #define BTRFS_BLOCK_GROUP_SYSTEM (1ULL << 1)
714 #define BTRFS_BLOCK_GROUP_METADATA (1ULL << 2)
715 #define BTRFS_BLOCK_GROUP_RAID0 (1ULL << 3)
716 #define BTRFS_BLOCK_GROUP_RAID1 (1ULL << 4)
717 #define BTRFS_BLOCK_GROUP_DUP (1ULL << 5)
718 #define BTRFS_BLOCK_GROUP_RAID10 (1ULL << 6)
719 #define BTRFS_BLOCK_GROUP_RAID5 (1ULL << 7)
720 #define BTRFS_BLOCK_GROUP_RAID6 (1ULL << 8)
721 #define BTRFS_BLOCK_GROUP_RESERVED (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
722 BTRFS_SPACE_INFO_GLOBAL_RSV)
724 enum btrfs_raid_types {
735 #define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA | \
736 BTRFS_BLOCK_GROUP_SYSTEM | \
737 BTRFS_BLOCK_GROUP_METADATA)
739 #define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 | \
740 BTRFS_BLOCK_GROUP_RAID1 | \
741 BTRFS_BLOCK_GROUP_RAID5 | \
742 BTRFS_BLOCK_GROUP_RAID6 | \
743 BTRFS_BLOCK_GROUP_DUP | \
744 BTRFS_BLOCK_GROUP_RAID10)
745 #define BTRFS_BLOCK_GROUP_RAID56_MASK (BTRFS_BLOCK_GROUP_RAID5 | \
746 BTRFS_BLOCK_GROUP_RAID6)
749 * We need a bit for restriper to be able to tell when chunks of type
750 * SINGLE are available. This "extended" profile format is used in
751 * fs_info->avail_*_alloc_bits (in-memory) and balance item fields
752 * (on-disk). The corresponding on-disk bit in chunk.type is reserved
753 * to avoid remappings between two formats in future.
755 #define BTRFS_AVAIL_ALLOC_BIT_SINGLE (1ULL << 48)
758 * A fake block group type that is used to communicate global block reserve
759 * size to userspace via the SPACE_INFO ioctl.
761 #define BTRFS_SPACE_INFO_GLOBAL_RSV (1ULL << 49)
763 #define BTRFS_EXTENDED_PROFILE_MASK (BTRFS_BLOCK_GROUP_PROFILE_MASK | \
764 BTRFS_AVAIL_ALLOC_BIT_SINGLE)
766 #endif /* __BTRFS_BTRFS_TREE_H__ */